Tue, 19 May 2015 15:49:27 +0200
8061715: gc/g1/TestShrinkAuxiliaryData15.java fails with java.lang.RuntimeException: heap decommit failed - after > before
Summary: added WhiteBox methods to count regions and exact aux data sizes
Reviewed-by: jwilhelm, brutisso
1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess.
27 #endif
29 #include "precompiled.hpp"
30 #include "classfile/metadataOnStackMark.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/icBuffer.hpp"
33 #include "gc_implementation/g1/bufferingOopClosure.hpp"
34 #include "gc_implementation/g1/concurrentG1Refine.hpp"
35 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
36 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
37 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
38 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
39 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
40 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
41 #include "gc_implementation/g1/g1EvacFailure.hpp"
42 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
43 #include "gc_implementation/g1/g1Log.hpp"
44 #include "gc_implementation/g1/g1MarkSweep.hpp"
45 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
46 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
47 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
48 #include "gc_implementation/g1/g1RemSet.inline.hpp"
49 #include "gc_implementation/g1/g1RootProcessor.hpp"
50 #include "gc_implementation/g1/g1StringDedup.hpp"
51 #include "gc_implementation/g1/g1YCTypes.hpp"
52 #include "gc_implementation/g1/heapRegion.inline.hpp"
53 #include "gc_implementation/g1/heapRegionRemSet.hpp"
54 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
55 #include "gc_implementation/g1/vm_operations_g1.hpp"
56 #include "gc_implementation/shared/gcHeapSummary.hpp"
57 #include "gc_implementation/shared/gcTimer.hpp"
58 #include "gc_implementation/shared/gcTrace.hpp"
59 #include "gc_implementation/shared/gcTraceTime.hpp"
60 #include "gc_implementation/shared/isGCActiveMark.hpp"
61 #include "memory/allocation.hpp"
62 #include "memory/gcLocker.inline.hpp"
63 #include "memory/generationSpec.hpp"
64 #include "memory/iterator.hpp"
65 #include "memory/referenceProcessor.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "oops/oop.pcgc.inline.hpp"
68 #include "runtime/orderAccess.inline.hpp"
69 #include "runtime/vmThread.hpp"
71 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
73 // turn it on so that the contents of the young list (scan-only /
74 // to-be-collected) are printed at "strategic" points before / during
75 // / after the collection --- this is useful for debugging
76 #define YOUNG_LIST_VERBOSE 0
77 // CURRENT STATUS
78 // This file is under construction. Search for "FIXME".
80 // INVARIANTS/NOTES
81 //
82 // All allocation activity covered by the G1CollectedHeap interface is
83 // serialized by acquiring the HeapLock. This happens in mem_allocate
84 // and allocate_new_tlab, which are the "entry" points to the
85 // allocation code from the rest of the JVM. (Note that this does not
86 // apply to TLAB allocation, which is not part of this interface: it
87 // is done by clients of this interface.)
89 // Local to this file.
91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
92 bool _concurrent;
93 public:
94 RefineCardTableEntryClosure() : _concurrent(true) { }
96 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
97 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
98 // This path is executed by the concurrent refine or mutator threads,
99 // concurrently, and so we do not care if card_ptr contains references
100 // that point into the collection set.
101 assert(!oops_into_cset, "should be");
103 if (_concurrent && SuspendibleThreadSet::should_yield()) {
104 // Caller will actually yield.
105 return false;
106 }
107 // Otherwise, we finished successfully; return true.
108 return true;
109 }
111 void set_concurrent(bool b) { _concurrent = b; }
112 };
115 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
116 size_t _num_processed;
117 CardTableModRefBS* _ctbs;
118 int _histo[256];
120 public:
121 ClearLoggedCardTableEntryClosure() :
122 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
123 {
124 for (int i = 0; i < 256; i++) _histo[i] = 0;
125 }
127 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
128 unsigned char* ujb = (unsigned char*)card_ptr;
129 int ind = (int)(*ujb);
130 _histo[ind]++;
132 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
133 _num_processed++;
135 return true;
136 }
138 size_t num_processed() { return _num_processed; }
140 void print_histo() {
141 gclog_or_tty->print_cr("Card table value histogram:");
142 for (int i = 0; i < 256; i++) {
143 if (_histo[i] != 0) {
144 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
145 }
146 }
147 }
148 };
150 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
151 private:
152 size_t _num_processed;
154 public:
155 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
157 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
158 *card_ptr = CardTableModRefBS::dirty_card_val();
159 _num_processed++;
160 return true;
161 }
163 size_t num_processed() const { return _num_processed; }
164 };
166 YoungList::YoungList(G1CollectedHeap* g1h) :
167 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
168 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
169 guarantee(check_list_empty(false), "just making sure...");
170 }
172 void YoungList::push_region(HeapRegion *hr) {
173 assert(!hr->is_young(), "should not already be young");
174 assert(hr->get_next_young_region() == NULL, "cause it should!");
176 hr->set_next_young_region(_head);
177 _head = hr;
179 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
180 ++_length;
181 }
183 void YoungList::add_survivor_region(HeapRegion* hr) {
184 assert(hr->is_survivor(), "should be flagged as survivor region");
185 assert(hr->get_next_young_region() == NULL, "cause it should!");
187 hr->set_next_young_region(_survivor_head);
188 if (_survivor_head == NULL) {
189 _survivor_tail = hr;
190 }
191 _survivor_head = hr;
192 ++_survivor_length;
193 }
195 void YoungList::empty_list(HeapRegion* list) {
196 while (list != NULL) {
197 HeapRegion* next = list->get_next_young_region();
198 list->set_next_young_region(NULL);
199 list->uninstall_surv_rate_group();
200 // This is called before a Full GC and all the non-empty /
201 // non-humongous regions at the end of the Full GC will end up as
202 // old anyway.
203 list->set_old();
204 list = next;
205 }
206 }
208 void YoungList::empty_list() {
209 assert(check_list_well_formed(), "young list should be well formed");
211 empty_list(_head);
212 _head = NULL;
213 _length = 0;
215 empty_list(_survivor_head);
216 _survivor_head = NULL;
217 _survivor_tail = NULL;
218 _survivor_length = 0;
220 _last_sampled_rs_lengths = 0;
222 assert(check_list_empty(false), "just making sure...");
223 }
225 bool YoungList::check_list_well_formed() {
226 bool ret = true;
228 uint length = 0;
229 HeapRegion* curr = _head;
230 HeapRegion* last = NULL;
231 while (curr != NULL) {
232 if (!curr->is_young()) {
233 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
234 "incorrectly tagged (y: %d, surv: %d)",
235 curr->bottom(), curr->end(),
236 curr->is_young(), curr->is_survivor());
237 ret = false;
238 }
239 ++length;
240 last = curr;
241 curr = curr->get_next_young_region();
242 }
243 ret = ret && (length == _length);
245 if (!ret) {
246 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
247 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
248 length, _length);
249 }
251 return ret;
252 }
254 bool YoungList::check_list_empty(bool check_sample) {
255 bool ret = true;
257 if (_length != 0) {
258 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
259 _length);
260 ret = false;
261 }
262 if (check_sample && _last_sampled_rs_lengths != 0) {
263 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
264 ret = false;
265 }
266 if (_head != NULL) {
267 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
268 ret = false;
269 }
270 if (!ret) {
271 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
272 }
274 return ret;
275 }
277 void
278 YoungList::rs_length_sampling_init() {
279 _sampled_rs_lengths = 0;
280 _curr = _head;
281 }
283 bool
284 YoungList::rs_length_sampling_more() {
285 return _curr != NULL;
286 }
288 void
289 YoungList::rs_length_sampling_next() {
290 assert( _curr != NULL, "invariant" );
291 size_t rs_length = _curr->rem_set()->occupied();
293 _sampled_rs_lengths += rs_length;
295 // The current region may not yet have been added to the
296 // incremental collection set (it gets added when it is
297 // retired as the current allocation region).
298 if (_curr->in_collection_set()) {
299 // Update the collection set policy information for this region
300 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
301 }
303 _curr = _curr->get_next_young_region();
304 if (_curr == NULL) {
305 _last_sampled_rs_lengths = _sampled_rs_lengths;
306 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
307 }
308 }
310 void
311 YoungList::reset_auxilary_lists() {
312 guarantee( is_empty(), "young list should be empty" );
313 assert(check_list_well_formed(), "young list should be well formed");
315 // Add survivor regions to SurvRateGroup.
316 _g1h->g1_policy()->note_start_adding_survivor_regions();
317 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
319 int young_index_in_cset = 0;
320 for (HeapRegion* curr = _survivor_head;
321 curr != NULL;
322 curr = curr->get_next_young_region()) {
323 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
325 // The region is a non-empty survivor so let's add it to
326 // the incremental collection set for the next evacuation
327 // pause.
328 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
329 young_index_in_cset += 1;
330 }
331 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
332 _g1h->g1_policy()->note_stop_adding_survivor_regions();
334 _head = _survivor_head;
335 _length = _survivor_length;
336 if (_survivor_head != NULL) {
337 assert(_survivor_tail != NULL, "cause it shouldn't be");
338 assert(_survivor_length > 0, "invariant");
339 _survivor_tail->set_next_young_region(NULL);
340 }
342 // Don't clear the survivor list handles until the start of
343 // the next evacuation pause - we need it in order to re-tag
344 // the survivor regions from this evacuation pause as 'young'
345 // at the start of the next.
347 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
349 assert(check_list_well_formed(), "young list should be well formed");
350 }
352 void YoungList::print() {
353 HeapRegion* lists[] = {_head, _survivor_head};
354 const char* names[] = {"YOUNG", "SURVIVOR"};
356 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
357 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
358 HeapRegion *curr = lists[list];
359 if (curr == NULL)
360 gclog_or_tty->print_cr(" empty");
361 while (curr != NULL) {
362 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
363 HR_FORMAT_PARAMS(curr),
364 curr->prev_top_at_mark_start(),
365 curr->next_top_at_mark_start(),
366 curr->age_in_surv_rate_group_cond());
367 curr = curr->get_next_young_region();
368 }
369 }
371 gclog_or_tty->cr();
372 }
374 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
375 OtherRegionsTable::invalidate(start_idx, num_regions);
376 }
378 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
379 // The from card cache is not the memory that is actually committed. So we cannot
380 // take advantage of the zero_filled parameter.
381 reset_from_card_cache(start_idx, num_regions);
382 }
384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
385 {
386 // Claim the right to put the region on the dirty cards region list
387 // by installing a self pointer.
388 HeapRegion* next = hr->get_next_dirty_cards_region();
389 if (next == NULL) {
390 HeapRegion* res = (HeapRegion*)
391 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
392 NULL);
393 if (res == NULL) {
394 HeapRegion* head;
395 do {
396 // Put the region to the dirty cards region list.
397 head = _dirty_cards_region_list;
398 next = (HeapRegion*)
399 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
400 if (next == head) {
401 assert(hr->get_next_dirty_cards_region() == hr,
402 "hr->get_next_dirty_cards_region() != hr");
403 if (next == NULL) {
404 // The last region in the list points to itself.
405 hr->set_next_dirty_cards_region(hr);
406 } else {
407 hr->set_next_dirty_cards_region(next);
408 }
409 }
410 } while (next != head);
411 }
412 }
413 }
415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
416 {
417 HeapRegion* head;
418 HeapRegion* hr;
419 do {
420 head = _dirty_cards_region_list;
421 if (head == NULL) {
422 return NULL;
423 }
424 HeapRegion* new_head = head->get_next_dirty_cards_region();
425 if (head == new_head) {
426 // The last region.
427 new_head = NULL;
428 }
429 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
430 head);
431 } while (hr != head);
432 assert(hr != NULL, "invariant");
433 hr->set_next_dirty_cards_region(NULL);
434 return hr;
435 }
437 #ifdef ASSERT
438 // A region is added to the collection set as it is retired
439 // so an address p can point to a region which will be in the
440 // collection set but has not yet been retired. This method
441 // therefore is only accurate during a GC pause after all
442 // regions have been retired. It is used for debugging
443 // to check if an nmethod has references to objects that can
444 // be move during a partial collection. Though it can be
445 // inaccurate, it is sufficient for G1 because the conservative
446 // implementation of is_scavengable() for G1 will indicate that
447 // all nmethods must be scanned during a partial collection.
448 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
449 if (p == NULL) {
450 return false;
451 }
452 return heap_region_containing(p)->in_collection_set();
453 }
454 #endif
456 // Returns true if the reference points to an object that
457 // can move in an incremental collection.
458 bool G1CollectedHeap::is_scavengable(const void* p) {
459 HeapRegion* hr = heap_region_containing(p);
460 return !hr->isHumongous();
461 }
463 void G1CollectedHeap::check_ct_logs_at_safepoint() {
464 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
465 CardTableModRefBS* ct_bs = g1_barrier_set();
467 // Count the dirty cards at the start.
468 CountNonCleanMemRegionClosure count1(this);
469 ct_bs->mod_card_iterate(&count1);
470 int orig_count = count1.n();
472 // First clear the logged cards.
473 ClearLoggedCardTableEntryClosure clear;
474 dcqs.apply_closure_to_all_completed_buffers(&clear);
475 dcqs.iterate_closure_all_threads(&clear, false);
476 clear.print_histo();
478 // Now ensure that there's no dirty cards.
479 CountNonCleanMemRegionClosure count2(this);
480 ct_bs->mod_card_iterate(&count2);
481 if (count2.n() != 0) {
482 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
483 count2.n(), orig_count);
484 }
485 guarantee(count2.n() == 0, "Card table should be clean.");
487 RedirtyLoggedCardTableEntryClosure redirty;
488 dcqs.apply_closure_to_all_completed_buffers(&redirty);
489 dcqs.iterate_closure_all_threads(&redirty, false);
490 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
491 clear.num_processed(), orig_count);
492 guarantee(redirty.num_processed() == clear.num_processed(),
493 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
494 redirty.num_processed(), clear.num_processed()));
496 CountNonCleanMemRegionClosure count3(this);
497 ct_bs->mod_card_iterate(&count3);
498 if (count3.n() != orig_count) {
499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
500 orig_count, count3.n());
501 guarantee(count3.n() >= orig_count, "Should have restored them all.");
502 }
503 }
505 // Private class members.
507 G1CollectedHeap* G1CollectedHeap::_g1h;
509 // Private methods.
511 HeapRegion*
512 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
513 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
514 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
515 if (!_secondary_free_list.is_empty()) {
516 if (G1ConcRegionFreeingVerbose) {
517 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
518 "secondary_free_list has %u entries",
519 _secondary_free_list.length());
520 }
521 // It looks as if there are free regions available on the
522 // secondary_free_list. Let's move them to the free_list and try
523 // again to allocate from it.
524 append_secondary_free_list();
526 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
527 "empty we should have moved at least one entry to the free_list");
528 HeapRegion* res = _hrm.allocate_free_region(is_old);
529 if (G1ConcRegionFreeingVerbose) {
530 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
531 "allocated "HR_FORMAT" from secondary_free_list",
532 HR_FORMAT_PARAMS(res));
533 }
534 return res;
535 }
537 // Wait here until we get notified either when (a) there are no
538 // more free regions coming or (b) some regions have been moved on
539 // the secondary_free_list.
540 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
541 }
543 if (G1ConcRegionFreeingVerbose) {
544 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
545 "could not allocate from secondary_free_list");
546 }
547 return NULL;
548 }
550 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
551 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
552 "the only time we use this to allocate a humongous region is "
553 "when we are allocating a single humongous region");
555 HeapRegion* res;
556 if (G1StressConcRegionFreeing) {
557 if (!_secondary_free_list.is_empty()) {
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "forced to look at the secondary_free_list");
561 }
562 res = new_region_try_secondary_free_list(is_old);
563 if (res != NULL) {
564 return res;
565 }
566 }
567 }
569 res = _hrm.allocate_free_region(is_old);
571 if (res == NULL) {
572 if (G1ConcRegionFreeingVerbose) {
573 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
574 "res == NULL, trying the secondary_free_list");
575 }
576 res = new_region_try_secondary_free_list(is_old);
577 }
578 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
579 // Currently, only attempts to allocate GC alloc regions set
580 // do_expand to true. So, we should only reach here during a
581 // safepoint. If this assumption changes we might have to
582 // reconsider the use of _expand_heap_after_alloc_failure.
583 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
585 ergo_verbose1(ErgoHeapSizing,
586 "attempt heap expansion",
587 ergo_format_reason("region allocation request failed")
588 ergo_format_byte("allocation request"),
589 word_size * HeapWordSize);
590 if (expand(word_size * HeapWordSize)) {
591 // Given that expand() succeeded in expanding the heap, and we
592 // always expand the heap by an amount aligned to the heap
593 // region size, the free list should in theory not be empty.
594 // In either case allocate_free_region() will check for NULL.
595 res = _hrm.allocate_free_region(is_old);
596 } else {
597 _expand_heap_after_alloc_failure = false;
598 }
599 }
600 return res;
601 }
603 HeapWord*
604 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
605 uint num_regions,
606 size_t word_size,
607 AllocationContext_t context) {
608 assert(first != G1_NO_HRM_INDEX, "pre-condition");
609 assert(isHumongous(word_size), "word_size should be humongous");
610 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
612 // Index of last region in the series + 1.
613 uint last = first + num_regions;
615 // We need to initialize the region(s) we just discovered. This is
616 // a bit tricky given that it can happen concurrently with
617 // refinement threads refining cards on these regions and
618 // potentially wanting to refine the BOT as they are scanning
619 // those cards (this can happen shortly after a cleanup; see CR
620 // 6991377). So we have to set up the region(s) carefully and in
621 // a specific order.
623 // The word size sum of all the regions we will allocate.
624 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
625 assert(word_size <= word_size_sum, "sanity");
627 // This will be the "starts humongous" region.
628 HeapRegion* first_hr = region_at(first);
629 // The header of the new object will be placed at the bottom of
630 // the first region.
631 HeapWord* new_obj = first_hr->bottom();
632 // This will be the new end of the first region in the series that
633 // should also match the end of the last region in the series.
634 HeapWord* new_end = new_obj + word_size_sum;
635 // This will be the new top of the first region that will reflect
636 // this allocation.
637 HeapWord* new_top = new_obj + word_size;
639 // First, we need to zero the header of the space that we will be
640 // allocating. When we update top further down, some refinement
641 // threads might try to scan the region. By zeroing the header we
642 // ensure that any thread that will try to scan the region will
643 // come across the zero klass word and bail out.
644 //
645 // NOTE: It would not have been correct to have used
646 // CollectedHeap::fill_with_object() and make the space look like
647 // an int array. The thread that is doing the allocation will
648 // later update the object header to a potentially different array
649 // type and, for a very short period of time, the klass and length
650 // fields will be inconsistent. This could cause a refinement
651 // thread to calculate the object size incorrectly.
652 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
654 // We will set up the first region as "starts humongous". This
655 // will also update the BOT covering all the regions to reflect
656 // that there is a single object that starts at the bottom of the
657 // first region.
658 first_hr->set_startsHumongous(new_top, new_end);
659 first_hr->set_allocation_context(context);
660 // Then, if there are any, we will set up the "continues
661 // humongous" regions.
662 HeapRegion* hr = NULL;
663 for (uint i = first + 1; i < last; ++i) {
664 hr = region_at(i);
665 hr->set_continuesHumongous(first_hr);
666 hr->set_allocation_context(context);
667 }
668 // If we have "continues humongous" regions (hr != NULL), then the
669 // end of the last one should match new_end.
670 assert(hr == NULL || hr->end() == new_end, "sanity");
672 // Up to this point no concurrent thread would have been able to
673 // do any scanning on any region in this series. All the top
674 // fields still point to bottom, so the intersection between
675 // [bottom,top] and [card_start,card_end] will be empty. Before we
676 // update the top fields, we'll do a storestore to make sure that
677 // no thread sees the update to top before the zeroing of the
678 // object header and the BOT initialization.
679 OrderAccess::storestore();
681 // Now that the BOT and the object header have been initialized,
682 // we can update top of the "starts humongous" region.
683 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
684 "new_top should be in this region");
685 first_hr->set_top(new_top);
686 if (_hr_printer.is_active()) {
687 HeapWord* bottom = first_hr->bottom();
688 HeapWord* end = first_hr->orig_end();
689 if ((first + 1) == last) {
690 // the series has a single humongous region
691 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
692 } else {
693 // the series has more than one humongous regions
694 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
695 }
696 }
698 // Now, we will update the top fields of the "continues humongous"
699 // regions. The reason we need to do this is that, otherwise,
700 // these regions would look empty and this will confuse parts of
701 // G1. For example, the code that looks for a consecutive number
702 // of empty regions will consider them empty and try to
703 // re-allocate them. We can extend is_empty() to also include
704 // !continuesHumongous(), but it is easier to just update the top
705 // fields here. The way we set top for all regions (i.e., top ==
706 // end for all regions but the last one, top == new_top for the
707 // last one) is actually used when we will free up the humongous
708 // region in free_humongous_region().
709 hr = NULL;
710 for (uint i = first + 1; i < last; ++i) {
711 hr = region_at(i);
712 if ((i + 1) == last) {
713 // last continues humongous region
714 assert(hr->bottom() < new_top && new_top <= hr->end(),
715 "new_top should fall on this region");
716 hr->set_top(new_top);
717 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
718 } else {
719 // not last one
720 assert(new_top > hr->end(), "new_top should be above this region");
721 hr->set_top(hr->end());
722 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
723 }
724 }
725 // If we have continues humongous regions (hr != NULL), then the
726 // end of the last one should match new_end and its top should
727 // match new_top.
728 assert(hr == NULL ||
729 (hr->end() == new_end && hr->top() == new_top), "sanity");
730 check_bitmaps("Humongous Region Allocation", first_hr);
732 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
733 _allocator->increase_used(first_hr->used());
734 _humongous_set.add(first_hr);
736 return new_obj;
737 }
739 // If could fit into free regions w/o expansion, try.
740 // Otherwise, if can expand, do so.
741 // Otherwise, if using ex regions might help, try with ex given back.
742 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
743 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
745 verify_region_sets_optional();
747 uint first = G1_NO_HRM_INDEX;
748 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
750 if (obj_regions == 1) {
751 // Only one region to allocate, try to use a fast path by directly allocating
752 // from the free lists. Do not try to expand here, we will potentially do that
753 // later.
754 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
755 if (hr != NULL) {
756 first = hr->hrm_index();
757 }
758 } else {
759 // We can't allocate humongous regions spanning more than one region while
760 // cleanupComplete() is running, since some of the regions we find to be
761 // empty might not yet be added to the free list. It is not straightforward
762 // to know in which list they are on so that we can remove them. We only
763 // need to do this if we need to allocate more than one region to satisfy the
764 // current humongous allocation request. If we are only allocating one region
765 // we use the one-region region allocation code (see above), that already
766 // potentially waits for regions from the secondary free list.
767 wait_while_free_regions_coming();
768 append_secondary_free_list_if_not_empty_with_lock();
770 // Policy: Try only empty regions (i.e. already committed first). Maybe we
771 // are lucky enough to find some.
772 first = _hrm.find_contiguous_only_empty(obj_regions);
773 if (first != G1_NO_HRM_INDEX) {
774 _hrm.allocate_free_regions_starting_at(first, obj_regions);
775 }
776 }
778 if (first == G1_NO_HRM_INDEX) {
779 // Policy: We could not find enough regions for the humongous object in the
780 // free list. Look through the heap to find a mix of free and uncommitted regions.
781 // If so, try expansion.
782 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
783 if (first != G1_NO_HRM_INDEX) {
784 // We found something. Make sure these regions are committed, i.e. expand
785 // the heap. Alternatively we could do a defragmentation GC.
786 ergo_verbose1(ErgoHeapSizing,
787 "attempt heap expansion",
788 ergo_format_reason("humongous allocation request failed")
789 ergo_format_byte("allocation request"),
790 word_size * HeapWordSize);
792 _hrm.expand_at(first, obj_regions);
793 g1_policy()->record_new_heap_size(num_regions());
795 #ifdef ASSERT
796 for (uint i = first; i < first + obj_regions; ++i) {
797 HeapRegion* hr = region_at(i);
798 assert(hr->is_free(), "sanity");
799 assert(hr->is_empty(), "sanity");
800 assert(is_on_master_free_list(hr), "sanity");
801 }
802 #endif
803 _hrm.allocate_free_regions_starting_at(first, obj_regions);
804 } else {
805 // Policy: Potentially trigger a defragmentation GC.
806 }
807 }
809 HeapWord* result = NULL;
810 if (first != G1_NO_HRM_INDEX) {
811 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
812 word_size, context);
813 assert(result != NULL, "it should always return a valid result");
815 // A successful humongous object allocation changes the used space
816 // information of the old generation so we need to recalculate the
817 // sizes and update the jstat counters here.
818 g1mm()->update_sizes();
819 }
821 verify_region_sets_optional();
823 return result;
824 }
826 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
827 assert_heap_not_locked_and_not_at_safepoint();
828 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
830 uint dummy_gc_count_before;
831 uint dummy_gclocker_retry_count = 0;
832 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
833 }
835 HeapWord*
836 G1CollectedHeap::mem_allocate(size_t word_size,
837 bool* gc_overhead_limit_was_exceeded) {
838 assert_heap_not_locked_and_not_at_safepoint();
840 // Loop until the allocation is satisfied, or unsatisfied after GC.
841 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
842 uint gc_count_before;
844 HeapWord* result = NULL;
845 if (!isHumongous(word_size)) {
846 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
847 } else {
848 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
849 }
850 if (result != NULL) {
851 return result;
852 }
854 // Create the garbage collection operation...
855 VM_G1CollectForAllocation op(gc_count_before, word_size);
856 op.set_allocation_context(AllocationContext::current());
858 // ...and get the VM thread to execute it.
859 VMThread::execute(&op);
861 if (op.prologue_succeeded() && op.pause_succeeded()) {
862 // If the operation was successful we'll return the result even
863 // if it is NULL. If the allocation attempt failed immediately
864 // after a Full GC, it's unlikely we'll be able to allocate now.
865 HeapWord* result = op.result();
866 if (result != NULL && !isHumongous(word_size)) {
867 // Allocations that take place on VM operations do not do any
868 // card dirtying and we have to do it here. We only have to do
869 // this for non-humongous allocations, though.
870 dirty_young_block(result, word_size);
871 }
872 return result;
873 } else {
874 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
875 return NULL;
876 }
877 assert(op.result() == NULL,
878 "the result should be NULL if the VM op did not succeed");
879 }
881 // Give a warning if we seem to be looping forever.
882 if ((QueuedAllocationWarningCount > 0) &&
883 (try_count % QueuedAllocationWarningCount == 0)) {
884 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
885 }
886 }
888 ShouldNotReachHere();
889 return NULL;
890 }
892 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
893 AllocationContext_t context,
894 uint* gc_count_before_ret,
895 uint* gclocker_retry_count_ret) {
896 // Make sure you read the note in attempt_allocation_humongous().
898 assert_heap_not_locked_and_not_at_safepoint();
899 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
900 "be called for humongous allocation requests");
902 // We should only get here after the first-level allocation attempt
903 // (attempt_allocation()) failed to allocate.
905 // We will loop until a) we manage to successfully perform the
906 // allocation or b) we successfully schedule a collection which
907 // fails to perform the allocation. b) is the only case when we'll
908 // return NULL.
909 HeapWord* result = NULL;
910 for (int try_count = 1; /* we'll return */; try_count += 1) {
911 bool should_try_gc;
912 uint gc_count_before;
914 {
915 MutexLockerEx x(Heap_lock);
916 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
917 false /* bot_updates */);
918 if (result != NULL) {
919 return result;
920 }
922 // If we reach here, attempt_allocation_locked() above failed to
923 // allocate a new region. So the mutator alloc region should be NULL.
924 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
926 if (GC_locker::is_active_and_needs_gc()) {
927 if (g1_policy()->can_expand_young_list()) {
928 // No need for an ergo verbose message here,
929 // can_expand_young_list() does this when it returns true.
930 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
931 false /* bot_updates */);
932 if (result != NULL) {
933 return result;
934 }
935 }
936 should_try_gc = false;
937 } else {
938 // The GCLocker may not be active but the GCLocker initiated
939 // GC may not yet have been performed (GCLocker::needs_gc()
940 // returns true). In this case we do not try this GC and
941 // wait until the GCLocker initiated GC is performed, and
942 // then retry the allocation.
943 if (GC_locker::needs_gc()) {
944 should_try_gc = false;
945 } else {
946 // Read the GC count while still holding the Heap_lock.
947 gc_count_before = total_collections();
948 should_try_gc = true;
949 }
950 }
951 }
953 if (should_try_gc) {
954 bool succeeded;
955 result = do_collection_pause(word_size, gc_count_before, &succeeded,
956 GCCause::_g1_inc_collection_pause);
957 if (result != NULL) {
958 assert(succeeded, "only way to get back a non-NULL result");
959 return result;
960 }
962 if (succeeded) {
963 // If we get here we successfully scheduled a collection which
964 // failed to allocate. No point in trying to allocate
965 // further. We'll just return NULL.
966 MutexLockerEx x(Heap_lock);
967 *gc_count_before_ret = total_collections();
968 return NULL;
969 }
970 } else {
971 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
972 MutexLockerEx x(Heap_lock);
973 *gc_count_before_ret = total_collections();
974 return NULL;
975 }
976 // The GCLocker is either active or the GCLocker initiated
977 // GC has not yet been performed. Stall until it is and
978 // then retry the allocation.
979 GC_locker::stall_until_clear();
980 (*gclocker_retry_count_ret) += 1;
981 }
983 // We can reach here if we were unsuccessful in scheduling a
984 // collection (because another thread beat us to it) or if we were
985 // stalled due to the GC locker. In either can we should retry the
986 // allocation attempt in case another thread successfully
987 // performed a collection and reclaimed enough space. We do the
988 // first attempt (without holding the Heap_lock) here and the
989 // follow-on attempt will be at the start of the next loop
990 // iteration (after taking the Heap_lock).
991 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
992 false /* bot_updates */);
993 if (result != NULL) {
994 return result;
995 }
997 // Give a warning if we seem to be looping forever.
998 if ((QueuedAllocationWarningCount > 0) &&
999 (try_count % QueuedAllocationWarningCount == 0)) {
1000 warning("G1CollectedHeap::attempt_allocation_slow() "
1001 "retries %d times", try_count);
1002 }
1003 }
1005 ShouldNotReachHere();
1006 return NULL;
1007 }
1009 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1010 uint* gc_count_before_ret,
1011 uint* gclocker_retry_count_ret) {
1012 // The structure of this method has a lot of similarities to
1013 // attempt_allocation_slow(). The reason these two were not merged
1014 // into a single one is that such a method would require several "if
1015 // allocation is not humongous do this, otherwise do that"
1016 // conditional paths which would obscure its flow. In fact, an early
1017 // version of this code did use a unified method which was harder to
1018 // follow and, as a result, it had subtle bugs that were hard to
1019 // track down. So keeping these two methods separate allows each to
1020 // be more readable. It will be good to keep these two in sync as
1021 // much as possible.
1023 assert_heap_not_locked_and_not_at_safepoint();
1024 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1025 "should only be called for humongous allocations");
1027 // Humongous objects can exhaust the heap quickly, so we should check if we
1028 // need to start a marking cycle at each humongous object allocation. We do
1029 // the check before we do the actual allocation. The reason for doing it
1030 // before the allocation is that we avoid having to keep track of the newly
1031 // allocated memory while we do a GC.
1032 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1033 word_size)) {
1034 collect(GCCause::_g1_humongous_allocation);
1035 }
1037 // We will loop until a) we manage to successfully perform the
1038 // allocation or b) we successfully schedule a collection which
1039 // fails to perform the allocation. b) is the only case when we'll
1040 // return NULL.
1041 HeapWord* result = NULL;
1042 for (int try_count = 1; /* we'll return */; try_count += 1) {
1043 bool should_try_gc;
1044 uint gc_count_before;
1046 {
1047 MutexLockerEx x(Heap_lock);
1049 // Given that humongous objects are not allocated in young
1050 // regions, we'll first try to do the allocation without doing a
1051 // collection hoping that there's enough space in the heap.
1052 result = humongous_obj_allocate(word_size, AllocationContext::current());
1053 if (result != NULL) {
1054 return result;
1055 }
1057 if (GC_locker::is_active_and_needs_gc()) {
1058 should_try_gc = false;
1059 } else {
1060 // The GCLocker may not be active but the GCLocker initiated
1061 // GC may not yet have been performed (GCLocker::needs_gc()
1062 // returns true). In this case we do not try this GC and
1063 // wait until the GCLocker initiated GC is performed, and
1064 // then retry the allocation.
1065 if (GC_locker::needs_gc()) {
1066 should_try_gc = false;
1067 } else {
1068 // Read the GC count while still holding the Heap_lock.
1069 gc_count_before = total_collections();
1070 should_try_gc = true;
1071 }
1072 }
1073 }
1075 if (should_try_gc) {
1076 // If we failed to allocate the humongous object, we should try to
1077 // do a collection pause (if we're allowed) in case it reclaims
1078 // enough space for the allocation to succeed after the pause.
1080 bool succeeded;
1081 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1082 GCCause::_g1_humongous_allocation);
1083 if (result != NULL) {
1084 assert(succeeded, "only way to get back a non-NULL result");
1085 return result;
1086 }
1088 if (succeeded) {
1089 // If we get here we successfully scheduled a collection which
1090 // failed to allocate. No point in trying to allocate
1091 // further. We'll just return NULL.
1092 MutexLockerEx x(Heap_lock);
1093 *gc_count_before_ret = total_collections();
1094 return NULL;
1095 }
1096 } else {
1097 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1098 MutexLockerEx x(Heap_lock);
1099 *gc_count_before_ret = total_collections();
1100 return NULL;
1101 }
1102 // The GCLocker is either active or the GCLocker initiated
1103 // GC has not yet been performed. Stall until it is and
1104 // then retry the allocation.
1105 GC_locker::stall_until_clear();
1106 (*gclocker_retry_count_ret) += 1;
1107 }
1109 // We can reach here if we were unsuccessful in scheduling a
1110 // collection (because another thread beat us to it) or if we were
1111 // stalled due to the GC locker. In either can we should retry the
1112 // allocation attempt in case another thread successfully
1113 // performed a collection and reclaimed enough space. Give a
1114 // warning if we seem to be looping forever.
1116 if ((QueuedAllocationWarningCount > 0) &&
1117 (try_count % QueuedAllocationWarningCount == 0)) {
1118 warning("G1CollectedHeap::attempt_allocation_humongous() "
1119 "retries %d times", try_count);
1120 }
1121 }
1123 ShouldNotReachHere();
1124 return NULL;
1125 }
1127 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1128 AllocationContext_t context,
1129 bool expect_null_mutator_alloc_region) {
1130 assert_at_safepoint(true /* should_be_vm_thread */);
1131 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1132 !expect_null_mutator_alloc_region,
1133 "the current alloc region was unexpectedly found to be non-NULL");
1135 if (!isHumongous(word_size)) {
1136 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1137 false /* bot_updates */);
1138 } else {
1139 HeapWord* result = humongous_obj_allocate(word_size, context);
1140 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1141 g1_policy()->set_initiate_conc_mark_if_possible();
1142 }
1143 return result;
1144 }
1146 ShouldNotReachHere();
1147 }
1149 class PostMCRemSetClearClosure: public HeapRegionClosure {
1150 G1CollectedHeap* _g1h;
1151 ModRefBarrierSet* _mr_bs;
1152 public:
1153 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1154 _g1h(g1h), _mr_bs(mr_bs) {}
1156 bool doHeapRegion(HeapRegion* r) {
1157 HeapRegionRemSet* hrrs = r->rem_set();
1159 if (r->continuesHumongous()) {
1160 // We'll assert that the strong code root list and RSet is empty
1161 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1162 assert(hrrs->occupied() == 0, "RSet should be empty");
1163 return false;
1164 }
1166 _g1h->reset_gc_time_stamps(r);
1167 hrrs->clear();
1168 // You might think here that we could clear just the cards
1169 // corresponding to the used region. But no: if we leave a dirty card
1170 // in a region we might allocate into, then it would prevent that card
1171 // from being enqueued, and cause it to be missed.
1172 // Re: the performance cost: we shouldn't be doing full GC anyway!
1173 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1175 return false;
1176 }
1177 };
1179 void G1CollectedHeap::clear_rsets_post_compaction() {
1180 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1181 heap_region_iterate(&rs_clear);
1182 }
1184 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1185 G1CollectedHeap* _g1h;
1186 UpdateRSOopClosure _cl;
1187 int _worker_i;
1188 public:
1189 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1190 _cl(g1->g1_rem_set(), worker_i),
1191 _worker_i(worker_i),
1192 _g1h(g1)
1193 { }
1195 bool doHeapRegion(HeapRegion* r) {
1196 if (!r->continuesHumongous()) {
1197 _cl.set_from(r);
1198 r->oop_iterate(&_cl);
1199 }
1200 return false;
1201 }
1202 };
1204 class ParRebuildRSTask: public AbstractGangTask {
1205 G1CollectedHeap* _g1;
1206 public:
1207 ParRebuildRSTask(G1CollectedHeap* g1)
1208 : AbstractGangTask("ParRebuildRSTask"),
1209 _g1(g1)
1210 { }
1212 void work(uint worker_id) {
1213 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1214 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1215 _g1->workers()->active_workers(),
1216 HeapRegion::RebuildRSClaimValue);
1217 }
1218 };
1220 class PostCompactionPrinterClosure: public HeapRegionClosure {
1221 private:
1222 G1HRPrinter* _hr_printer;
1223 public:
1224 bool doHeapRegion(HeapRegion* hr) {
1225 assert(!hr->is_young(), "not expecting to find young regions");
1226 if (hr->is_free()) {
1227 // We only generate output for non-empty regions.
1228 } else if (hr->startsHumongous()) {
1229 if (hr->region_num() == 1) {
1230 // single humongous region
1231 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1232 } else {
1233 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1234 }
1235 } else if (hr->continuesHumongous()) {
1236 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1237 } else if (hr->is_old()) {
1238 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1239 } else {
1240 ShouldNotReachHere();
1241 }
1242 return false;
1243 }
1245 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1246 : _hr_printer(hr_printer) { }
1247 };
1249 void G1CollectedHeap::print_hrm_post_compaction() {
1250 PostCompactionPrinterClosure cl(hr_printer());
1251 heap_region_iterate(&cl);
1252 }
1254 bool G1CollectedHeap::do_collection(bool explicit_gc,
1255 bool clear_all_soft_refs,
1256 size_t word_size) {
1257 assert_at_safepoint(true /* should_be_vm_thread */);
1259 if (GC_locker::check_active_before_gc()) {
1260 return false;
1261 }
1263 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1264 gc_timer->register_gc_start();
1266 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1267 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1269 SvcGCMarker sgcm(SvcGCMarker::FULL);
1270 ResourceMark rm;
1272 print_heap_before_gc();
1273 trace_heap_before_gc(gc_tracer);
1275 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1277 verify_region_sets_optional();
1279 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1280 collector_policy()->should_clear_all_soft_refs();
1282 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1284 {
1285 IsGCActiveMark x;
1287 // Timing
1288 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1289 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1291 {
1292 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1293 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1294 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1296 double start = os::elapsedTime();
1297 g1_policy()->record_full_collection_start();
1299 // Note: When we have a more flexible GC logging framework that
1300 // allows us to add optional attributes to a GC log record we
1301 // could consider timing and reporting how long we wait in the
1302 // following two methods.
1303 wait_while_free_regions_coming();
1304 // If we start the compaction before the CM threads finish
1305 // scanning the root regions we might trip them over as we'll
1306 // be moving objects / updating references. So let's wait until
1307 // they are done. By telling them to abort, they should complete
1308 // early.
1309 _cm->root_regions()->abort();
1310 _cm->root_regions()->wait_until_scan_finished();
1311 append_secondary_free_list_if_not_empty_with_lock();
1313 gc_prologue(true);
1314 increment_total_collections(true /* full gc */);
1315 increment_old_marking_cycles_started();
1317 assert(used() == recalculate_used(), "Should be equal");
1319 verify_before_gc();
1321 check_bitmaps("Full GC Start");
1322 pre_full_gc_dump(gc_timer);
1324 COMPILER2_PRESENT(DerivedPointerTable::clear());
1326 // Disable discovery and empty the discovered lists
1327 // for the CM ref processor.
1328 ref_processor_cm()->disable_discovery();
1329 ref_processor_cm()->abandon_partial_discovery();
1330 ref_processor_cm()->verify_no_references_recorded();
1332 // Abandon current iterations of concurrent marking and concurrent
1333 // refinement, if any are in progress. We have to do this before
1334 // wait_until_scan_finished() below.
1335 concurrent_mark()->abort();
1337 // Make sure we'll choose a new allocation region afterwards.
1338 _allocator->release_mutator_alloc_region();
1339 _allocator->abandon_gc_alloc_regions();
1340 g1_rem_set()->cleanupHRRS();
1342 // We should call this after we retire any currently active alloc
1343 // regions so that all the ALLOC / RETIRE events are generated
1344 // before the start GC event.
1345 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1347 // We may have added regions to the current incremental collection
1348 // set between the last GC or pause and now. We need to clear the
1349 // incremental collection set and then start rebuilding it afresh
1350 // after this full GC.
1351 abandon_collection_set(g1_policy()->inc_cset_head());
1352 g1_policy()->clear_incremental_cset();
1353 g1_policy()->stop_incremental_cset_building();
1355 tear_down_region_sets(false /* free_list_only */);
1356 g1_policy()->set_gcs_are_young(true);
1358 // See the comments in g1CollectedHeap.hpp and
1359 // G1CollectedHeap::ref_processing_init() about
1360 // how reference processing currently works in G1.
1362 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1363 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1365 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1366 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1368 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1369 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1371 // Do collection work
1372 {
1373 HandleMark hm; // Discard invalid handles created during gc
1374 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1375 }
1377 assert(num_free_regions() == 0, "we should not have added any free regions");
1378 rebuild_region_sets(false /* free_list_only */);
1380 // Enqueue any discovered reference objects that have
1381 // not been removed from the discovered lists.
1382 ref_processor_stw()->enqueue_discovered_references();
1384 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1386 MemoryService::track_memory_usage();
1388 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1389 ref_processor_stw()->verify_no_references_recorded();
1391 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1392 ClassLoaderDataGraph::purge();
1393 MetaspaceAux::verify_metrics();
1395 // Note: since we've just done a full GC, concurrent
1396 // marking is no longer active. Therefore we need not
1397 // re-enable reference discovery for the CM ref processor.
1398 // That will be done at the start of the next marking cycle.
1399 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1400 ref_processor_cm()->verify_no_references_recorded();
1402 reset_gc_time_stamp();
1403 // Since everything potentially moved, we will clear all remembered
1404 // sets, and clear all cards. Later we will rebuild remembered
1405 // sets. We will also reset the GC time stamps of the regions.
1406 clear_rsets_post_compaction();
1407 check_gc_time_stamps();
1409 // Resize the heap if necessary.
1410 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1412 if (_hr_printer.is_active()) {
1413 // We should do this after we potentially resize the heap so
1414 // that all the COMMIT / UNCOMMIT events are generated before
1415 // the end GC event.
1417 print_hrm_post_compaction();
1418 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1419 }
1421 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1422 if (hot_card_cache->use_cache()) {
1423 hot_card_cache->reset_card_counts();
1424 hot_card_cache->reset_hot_cache();
1425 }
1427 // Rebuild remembered sets of all regions.
1428 if (G1CollectedHeap::use_parallel_gc_threads()) {
1429 uint n_workers =
1430 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1431 workers()->active_workers(),
1432 Threads::number_of_non_daemon_threads());
1433 assert(UseDynamicNumberOfGCThreads ||
1434 n_workers == workers()->total_workers(),
1435 "If not dynamic should be using all the workers");
1436 workers()->set_active_workers(n_workers);
1437 // Set parallel threads in the heap (_n_par_threads) only
1438 // before a parallel phase and always reset it to 0 after
1439 // the phase so that the number of parallel threads does
1440 // no get carried forward to a serial phase where there
1441 // may be code that is "possibly_parallel".
1442 set_par_threads(n_workers);
1444 ParRebuildRSTask rebuild_rs_task(this);
1445 assert(check_heap_region_claim_values(
1446 HeapRegion::InitialClaimValue), "sanity check");
1447 assert(UseDynamicNumberOfGCThreads ||
1448 workers()->active_workers() == workers()->total_workers(),
1449 "Unless dynamic should use total workers");
1450 // Use the most recent number of active workers
1451 assert(workers()->active_workers() > 0,
1452 "Active workers not properly set");
1453 set_par_threads(workers()->active_workers());
1454 workers()->run_task(&rebuild_rs_task);
1455 set_par_threads(0);
1456 assert(check_heap_region_claim_values(
1457 HeapRegion::RebuildRSClaimValue), "sanity check");
1458 reset_heap_region_claim_values();
1459 } else {
1460 RebuildRSOutOfRegionClosure rebuild_rs(this);
1461 heap_region_iterate(&rebuild_rs);
1462 }
1464 // Rebuild the strong code root lists for each region
1465 rebuild_strong_code_roots();
1467 if (true) { // FIXME
1468 MetaspaceGC::compute_new_size();
1469 }
1471 #ifdef TRACESPINNING
1472 ParallelTaskTerminator::print_termination_counts();
1473 #endif
1475 // Discard all rset updates
1476 JavaThread::dirty_card_queue_set().abandon_logs();
1477 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1479 _young_list->reset_sampled_info();
1480 // At this point there should be no regions in the
1481 // entire heap tagged as young.
1482 assert(check_young_list_empty(true /* check_heap */),
1483 "young list should be empty at this point");
1485 // Update the number of full collections that have been completed.
1486 increment_old_marking_cycles_completed(false /* concurrent */);
1488 _hrm.verify_optional();
1489 verify_region_sets_optional();
1491 verify_after_gc();
1493 // Clear the previous marking bitmap, if needed for bitmap verification.
1494 // Note we cannot do this when we clear the next marking bitmap in
1495 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1496 // objects marked during a full GC against the previous bitmap.
1497 // But we need to clear it before calling check_bitmaps below since
1498 // the full GC has compacted objects and updated TAMS but not updated
1499 // the prev bitmap.
1500 if (G1VerifyBitmaps) {
1501 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1502 }
1503 check_bitmaps("Full GC End");
1505 // Start a new incremental collection set for the next pause
1506 assert(g1_policy()->collection_set() == NULL, "must be");
1507 g1_policy()->start_incremental_cset_building();
1509 clear_cset_fast_test();
1511 _allocator->init_mutator_alloc_region();
1513 double end = os::elapsedTime();
1514 g1_policy()->record_full_collection_end();
1516 if (G1Log::fine()) {
1517 g1_policy()->print_heap_transition();
1518 }
1520 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1521 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1522 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1523 // before any GC notifications are raised.
1524 g1mm()->update_sizes();
1526 gc_epilogue(true);
1527 }
1529 if (G1Log::finer()) {
1530 g1_policy()->print_detailed_heap_transition(true /* full */);
1531 }
1533 print_heap_after_gc();
1534 trace_heap_after_gc(gc_tracer);
1536 post_full_gc_dump(gc_timer);
1538 gc_timer->register_gc_end();
1539 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1540 }
1542 return true;
1543 }
1545 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1546 // do_collection() will return whether it succeeded in performing
1547 // the GC. Currently, there is no facility on the
1548 // do_full_collection() API to notify the caller than the collection
1549 // did not succeed (e.g., because it was locked out by the GC
1550 // locker). So, right now, we'll ignore the return value.
1551 bool dummy = do_collection(true, /* explicit_gc */
1552 clear_all_soft_refs,
1553 0 /* word_size */);
1554 }
1556 // This code is mostly copied from TenuredGeneration.
1557 void
1558 G1CollectedHeap::
1559 resize_if_necessary_after_full_collection(size_t word_size) {
1560 // Include the current allocation, if any, and bytes that will be
1561 // pre-allocated to support collections, as "used".
1562 const size_t used_after_gc = used();
1563 const size_t capacity_after_gc = capacity();
1564 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1566 // This is enforced in arguments.cpp.
1567 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1568 "otherwise the code below doesn't make sense");
1570 // We don't have floating point command-line arguments
1571 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1572 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1573 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1574 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1576 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1577 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1579 // We have to be careful here as these two calculations can overflow
1580 // 32-bit size_t's.
1581 double used_after_gc_d = (double) used_after_gc;
1582 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1583 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1585 // Let's make sure that they are both under the max heap size, which
1586 // by default will make them fit into a size_t.
1587 double desired_capacity_upper_bound = (double) max_heap_size;
1588 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1589 desired_capacity_upper_bound);
1590 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1591 desired_capacity_upper_bound);
1593 // We can now safely turn them into size_t's.
1594 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1595 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1597 // This assert only makes sense here, before we adjust them
1598 // with respect to the min and max heap size.
1599 assert(minimum_desired_capacity <= maximum_desired_capacity,
1600 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1601 "maximum_desired_capacity = "SIZE_FORMAT,
1602 minimum_desired_capacity, maximum_desired_capacity));
1604 // Should not be greater than the heap max size. No need to adjust
1605 // it with respect to the heap min size as it's a lower bound (i.e.,
1606 // we'll try to make the capacity larger than it, not smaller).
1607 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1608 // Should not be less than the heap min size. No need to adjust it
1609 // with respect to the heap max size as it's an upper bound (i.e.,
1610 // we'll try to make the capacity smaller than it, not greater).
1611 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1613 if (capacity_after_gc < minimum_desired_capacity) {
1614 // Don't expand unless it's significant
1615 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1616 ergo_verbose4(ErgoHeapSizing,
1617 "attempt heap expansion",
1618 ergo_format_reason("capacity lower than "
1619 "min desired capacity after Full GC")
1620 ergo_format_byte("capacity")
1621 ergo_format_byte("occupancy")
1622 ergo_format_byte_perc("min desired capacity"),
1623 capacity_after_gc, used_after_gc,
1624 minimum_desired_capacity, (double) MinHeapFreeRatio);
1625 expand(expand_bytes);
1627 // No expansion, now see if we want to shrink
1628 } else if (capacity_after_gc > maximum_desired_capacity) {
1629 // Capacity too large, compute shrinking size
1630 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1631 ergo_verbose4(ErgoHeapSizing,
1632 "attempt heap shrinking",
1633 ergo_format_reason("capacity higher than "
1634 "max desired capacity after Full GC")
1635 ergo_format_byte("capacity")
1636 ergo_format_byte("occupancy")
1637 ergo_format_byte_perc("max desired capacity"),
1638 capacity_after_gc, used_after_gc,
1639 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1640 shrink(shrink_bytes);
1641 }
1642 }
1645 HeapWord*
1646 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1647 AllocationContext_t context,
1648 bool* succeeded) {
1649 assert_at_safepoint(true /* should_be_vm_thread */);
1651 *succeeded = true;
1652 // Let's attempt the allocation first.
1653 HeapWord* result =
1654 attempt_allocation_at_safepoint(word_size,
1655 context,
1656 false /* expect_null_mutator_alloc_region */);
1657 if (result != NULL) {
1658 assert(*succeeded, "sanity");
1659 return result;
1660 }
1662 // In a G1 heap, we're supposed to keep allocation from failing by
1663 // incremental pauses. Therefore, at least for now, we'll favor
1664 // expansion over collection. (This might change in the future if we can
1665 // do something smarter than full collection to satisfy a failed alloc.)
1666 result = expand_and_allocate(word_size, context);
1667 if (result != NULL) {
1668 assert(*succeeded, "sanity");
1669 return result;
1670 }
1672 // Expansion didn't work, we'll try to do a Full GC.
1673 bool gc_succeeded = do_collection(false, /* explicit_gc */
1674 false, /* clear_all_soft_refs */
1675 word_size);
1676 if (!gc_succeeded) {
1677 *succeeded = false;
1678 return NULL;
1679 }
1681 // Retry the allocation
1682 result = attempt_allocation_at_safepoint(word_size,
1683 context,
1684 true /* expect_null_mutator_alloc_region */);
1685 if (result != NULL) {
1686 assert(*succeeded, "sanity");
1687 return result;
1688 }
1690 // Then, try a Full GC that will collect all soft references.
1691 gc_succeeded = do_collection(false, /* explicit_gc */
1692 true, /* clear_all_soft_refs */
1693 word_size);
1694 if (!gc_succeeded) {
1695 *succeeded = false;
1696 return NULL;
1697 }
1699 // Retry the allocation once more
1700 result = attempt_allocation_at_safepoint(word_size,
1701 context,
1702 true /* expect_null_mutator_alloc_region */);
1703 if (result != NULL) {
1704 assert(*succeeded, "sanity");
1705 return result;
1706 }
1708 assert(!collector_policy()->should_clear_all_soft_refs(),
1709 "Flag should have been handled and cleared prior to this point");
1711 // What else? We might try synchronous finalization later. If the total
1712 // space available is large enough for the allocation, then a more
1713 // complete compaction phase than we've tried so far might be
1714 // appropriate.
1715 assert(*succeeded, "sanity");
1716 return NULL;
1717 }
1719 // Attempting to expand the heap sufficiently
1720 // to support an allocation of the given "word_size". If
1721 // successful, perform the allocation and return the address of the
1722 // allocated block, or else "NULL".
1724 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1725 assert_at_safepoint(true /* should_be_vm_thread */);
1727 verify_region_sets_optional();
1729 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1730 ergo_verbose1(ErgoHeapSizing,
1731 "attempt heap expansion",
1732 ergo_format_reason("allocation request failed")
1733 ergo_format_byte("allocation request"),
1734 word_size * HeapWordSize);
1735 if (expand(expand_bytes)) {
1736 _hrm.verify_optional();
1737 verify_region_sets_optional();
1738 return attempt_allocation_at_safepoint(word_size,
1739 context,
1740 false /* expect_null_mutator_alloc_region */);
1741 }
1742 return NULL;
1743 }
1745 bool G1CollectedHeap::expand(size_t expand_bytes) {
1746 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1747 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1748 HeapRegion::GrainBytes);
1749 ergo_verbose2(ErgoHeapSizing,
1750 "expand the heap",
1751 ergo_format_byte("requested expansion amount")
1752 ergo_format_byte("attempted expansion amount"),
1753 expand_bytes, aligned_expand_bytes);
1755 if (is_maximal_no_gc()) {
1756 ergo_verbose0(ErgoHeapSizing,
1757 "did not expand the heap",
1758 ergo_format_reason("heap already fully expanded"));
1759 return false;
1760 }
1762 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1763 assert(regions_to_expand > 0, "Must expand by at least one region");
1765 uint expanded_by = _hrm.expand_by(regions_to_expand);
1767 if (expanded_by > 0) {
1768 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1769 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1770 g1_policy()->record_new_heap_size(num_regions());
1771 } else {
1772 ergo_verbose0(ErgoHeapSizing,
1773 "did not expand the heap",
1774 ergo_format_reason("heap expansion operation failed"));
1775 // The expansion of the virtual storage space was unsuccessful.
1776 // Let's see if it was because we ran out of swap.
1777 if (G1ExitOnExpansionFailure &&
1778 _hrm.available() >= regions_to_expand) {
1779 // We had head room...
1780 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1781 }
1782 }
1783 return regions_to_expand > 0;
1784 }
1786 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1787 size_t aligned_shrink_bytes =
1788 ReservedSpace::page_align_size_down(shrink_bytes);
1789 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1790 HeapRegion::GrainBytes);
1791 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1793 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1794 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1796 ergo_verbose3(ErgoHeapSizing,
1797 "shrink the heap",
1798 ergo_format_byte("requested shrinking amount")
1799 ergo_format_byte("aligned shrinking amount")
1800 ergo_format_byte("attempted shrinking amount"),
1801 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1802 if (num_regions_removed > 0) {
1803 g1_policy()->record_new_heap_size(num_regions());
1804 } else {
1805 ergo_verbose0(ErgoHeapSizing,
1806 "did not shrink the heap",
1807 ergo_format_reason("heap shrinking operation failed"));
1808 }
1809 }
1811 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1812 verify_region_sets_optional();
1814 // We should only reach here at the end of a Full GC which means we
1815 // should not not be holding to any GC alloc regions. The method
1816 // below will make sure of that and do any remaining clean up.
1817 _allocator->abandon_gc_alloc_regions();
1819 // Instead of tearing down / rebuilding the free lists here, we
1820 // could instead use the remove_all_pending() method on free_list to
1821 // remove only the ones that we need to remove.
1822 tear_down_region_sets(true /* free_list_only */);
1823 shrink_helper(shrink_bytes);
1824 rebuild_region_sets(true /* free_list_only */);
1826 _hrm.verify_optional();
1827 verify_region_sets_optional();
1828 }
1830 // Public methods.
1832 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1833 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1834 #endif // _MSC_VER
1837 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1838 SharedHeap(policy_),
1839 _g1_policy(policy_),
1840 _dirty_card_queue_set(false),
1841 _into_cset_dirty_card_queue_set(false),
1842 _is_alive_closure_cm(this),
1843 _is_alive_closure_stw(this),
1844 _ref_processor_cm(NULL),
1845 _ref_processor_stw(NULL),
1846 _bot_shared(NULL),
1847 _evac_failure_scan_stack(NULL),
1848 _mark_in_progress(false),
1849 _cg1r(NULL),
1850 _g1mm(NULL),
1851 _refine_cte_cl(NULL),
1852 _full_collection(false),
1853 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1854 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1855 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1856 _humongous_reclaim_candidates(),
1857 _has_humongous_reclaim_candidates(false),
1858 _free_regions_coming(false),
1859 _young_list(new YoungList(this)),
1860 _gc_time_stamp(0),
1861 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1862 _old_plab_stats(OldPLABSize, PLABWeight),
1863 _expand_heap_after_alloc_failure(true),
1864 _surviving_young_words(NULL),
1865 _old_marking_cycles_started(0),
1866 _old_marking_cycles_completed(0),
1867 _concurrent_cycle_started(false),
1868 _heap_summary_sent(false),
1869 _in_cset_fast_test(),
1870 _dirty_cards_region_list(NULL),
1871 _worker_cset_start_region(NULL),
1872 _worker_cset_start_region_time_stamp(NULL),
1873 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1874 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1875 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1876 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1878 _g1h = this;
1880 _allocator = G1Allocator::create_allocator(_g1h);
1881 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1883 int n_queues = MAX2((int)ParallelGCThreads, 1);
1884 _task_queues = new RefToScanQueueSet(n_queues);
1886 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1887 assert(n_rem_sets > 0, "Invariant.");
1889 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1890 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1891 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1893 for (int i = 0; i < n_queues; i++) {
1894 RefToScanQueue* q = new RefToScanQueue();
1895 q->initialize();
1896 _task_queues->register_queue(i, q);
1897 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1898 }
1899 clear_cset_start_regions();
1901 // Initialize the G1EvacuationFailureALot counters and flags.
1902 NOT_PRODUCT(reset_evacuation_should_fail();)
1904 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1905 }
1907 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1908 size_t size,
1909 size_t translation_factor) {
1910 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1911 // Allocate a new reserved space, preferring to use large pages.
1912 ReservedSpace rs(size, preferred_page_size);
1913 G1RegionToSpaceMapper* result =
1914 G1RegionToSpaceMapper::create_mapper(rs,
1915 size,
1916 rs.alignment(),
1917 HeapRegion::GrainBytes,
1918 translation_factor,
1919 mtGC);
1920 if (TracePageSizes) {
1921 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1922 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1923 }
1924 return result;
1925 }
1927 jint G1CollectedHeap::initialize() {
1928 CollectedHeap::pre_initialize();
1929 os::enable_vtime();
1931 G1Log::init();
1933 // Necessary to satisfy locking discipline assertions.
1935 MutexLocker x(Heap_lock);
1937 // We have to initialize the printer before committing the heap, as
1938 // it will be used then.
1939 _hr_printer.set_active(G1PrintHeapRegions);
1941 // While there are no constraints in the GC code that HeapWordSize
1942 // be any particular value, there are multiple other areas in the
1943 // system which believe this to be true (e.g. oop->object_size in some
1944 // cases incorrectly returns the size in wordSize units rather than
1945 // HeapWordSize).
1946 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1948 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1949 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1950 size_t heap_alignment = collector_policy()->heap_alignment();
1952 // Ensure that the sizes are properly aligned.
1953 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1954 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1955 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1957 _refine_cte_cl = new RefineCardTableEntryClosure();
1959 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1961 // Reserve the maximum.
1963 // When compressed oops are enabled, the preferred heap base
1964 // is calculated by subtracting the requested size from the
1965 // 32Gb boundary and using the result as the base address for
1966 // heap reservation. If the requested size is not aligned to
1967 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1968 // into the ReservedHeapSpace constructor) then the actual
1969 // base of the reserved heap may end up differing from the
1970 // address that was requested (i.e. the preferred heap base).
1971 // If this happens then we could end up using a non-optimal
1972 // compressed oops mode.
1974 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1975 heap_alignment);
1977 // It is important to do this in a way such that concurrent readers can't
1978 // temporarily think something is in the heap. (I've actually seen this
1979 // happen in asserts: DLD.)
1980 _reserved.set_word_size(0);
1981 _reserved.set_start((HeapWord*)heap_rs.base());
1982 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1984 // Create the gen rem set (and barrier set) for the entire reserved region.
1985 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1986 set_barrier_set(rem_set()->bs());
1987 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1988 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1989 return JNI_ENOMEM;
1990 }
1992 // Also create a G1 rem set.
1993 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1995 // Carve out the G1 part of the heap.
1997 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1998 G1RegionToSpaceMapper* heap_storage =
1999 G1RegionToSpaceMapper::create_mapper(g1_rs,
2000 g1_rs.size(),
2001 UseLargePages ? os::large_page_size() : os::vm_page_size(),
2002 HeapRegion::GrainBytes,
2003 1,
2004 mtJavaHeap);
2005 heap_storage->set_mapping_changed_listener(&_listener);
2007 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2008 G1RegionToSpaceMapper* bot_storage =
2009 create_aux_memory_mapper("Block offset table",
2010 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2011 G1BlockOffsetSharedArray::N_bytes);
2013 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2014 G1RegionToSpaceMapper* cardtable_storage =
2015 create_aux_memory_mapper("Card table",
2016 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2017 G1BlockOffsetSharedArray::N_bytes);
2019 G1RegionToSpaceMapper* card_counts_storage =
2020 create_aux_memory_mapper("Card counts table",
2021 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2022 G1BlockOffsetSharedArray::N_bytes);
2024 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2025 G1RegionToSpaceMapper* prev_bitmap_storage =
2026 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
2027 G1RegionToSpaceMapper* next_bitmap_storage =
2028 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
2030 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2031 g1_barrier_set()->initialize(cardtable_storage);
2032 // Do later initialization work for concurrent refinement.
2033 _cg1r->init(card_counts_storage);
2035 // 6843694 - ensure that the maximum region index can fit
2036 // in the remembered set structures.
2037 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2038 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2040 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2041 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2042 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2043 "too many cards per region");
2045 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2047 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
2049 _g1h = this;
2051 {
2052 HeapWord* start = _hrm.reserved().start();
2053 HeapWord* end = _hrm.reserved().end();
2054 size_t granularity = HeapRegion::GrainBytes;
2056 _in_cset_fast_test.initialize(start, end, granularity);
2057 _humongous_reclaim_candidates.initialize(start, end, granularity);
2058 }
2060 // Create the ConcurrentMark data structure and thread.
2061 // (Must do this late, so that "max_regions" is defined.)
2062 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2063 if (_cm == NULL || !_cm->completed_initialization()) {
2064 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2065 return JNI_ENOMEM;
2066 }
2067 _cmThread = _cm->cmThread();
2069 // Initialize the from_card cache structure of HeapRegionRemSet.
2070 HeapRegionRemSet::init_heap(max_regions());
2072 // Now expand into the initial heap size.
2073 if (!expand(init_byte_size)) {
2074 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2075 return JNI_ENOMEM;
2076 }
2078 // Perform any initialization actions delegated to the policy.
2079 g1_policy()->init();
2081 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2082 SATB_Q_FL_lock,
2083 G1SATBProcessCompletedThreshold,
2084 Shared_SATB_Q_lock);
2086 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2087 DirtyCardQ_CBL_mon,
2088 DirtyCardQ_FL_lock,
2089 concurrent_g1_refine()->yellow_zone(),
2090 concurrent_g1_refine()->red_zone(),
2091 Shared_DirtyCardQ_lock);
2093 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2094 DirtyCardQ_CBL_mon,
2095 DirtyCardQ_FL_lock,
2096 -1, // never trigger processing
2097 -1, // no limit on length
2098 Shared_DirtyCardQ_lock,
2099 &JavaThread::dirty_card_queue_set());
2101 // Initialize the card queue set used to hold cards containing
2102 // references into the collection set.
2103 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2104 DirtyCardQ_CBL_mon,
2105 DirtyCardQ_FL_lock,
2106 -1, // never trigger processing
2107 -1, // no limit on length
2108 Shared_DirtyCardQ_lock,
2109 &JavaThread::dirty_card_queue_set());
2111 // In case we're keeping closure specialization stats, initialize those
2112 // counts and that mechanism.
2113 SpecializationStats::clear();
2115 // Here we allocate the dummy HeapRegion that is required by the
2116 // G1AllocRegion class.
2117 HeapRegion* dummy_region = _hrm.get_dummy_region();
2119 // We'll re-use the same region whether the alloc region will
2120 // require BOT updates or not and, if it doesn't, then a non-young
2121 // region will complain that it cannot support allocations without
2122 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2123 dummy_region->set_eden();
2124 // Make sure it's full.
2125 dummy_region->set_top(dummy_region->end());
2126 G1AllocRegion::setup(this, dummy_region);
2128 _allocator->init_mutator_alloc_region();
2130 // Do create of the monitoring and management support so that
2131 // values in the heap have been properly initialized.
2132 _g1mm = new G1MonitoringSupport(this);
2134 G1StringDedup::initialize();
2136 return JNI_OK;
2137 }
2139 void G1CollectedHeap::stop() {
2140 // Stop all concurrent threads. We do this to make sure these threads
2141 // do not continue to execute and access resources (e.g. gclog_or_tty)
2142 // that are destroyed during shutdown.
2143 _cg1r->stop();
2144 _cmThread->stop();
2145 if (G1StringDedup::is_enabled()) {
2146 G1StringDedup::stop();
2147 }
2148 }
2150 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2151 return HeapRegion::max_region_size();
2152 }
2154 void G1CollectedHeap::ref_processing_init() {
2155 // Reference processing in G1 currently works as follows:
2156 //
2157 // * There are two reference processor instances. One is
2158 // used to record and process discovered references
2159 // during concurrent marking; the other is used to
2160 // record and process references during STW pauses
2161 // (both full and incremental).
2162 // * Both ref processors need to 'span' the entire heap as
2163 // the regions in the collection set may be dotted around.
2164 //
2165 // * For the concurrent marking ref processor:
2166 // * Reference discovery is enabled at initial marking.
2167 // * Reference discovery is disabled and the discovered
2168 // references processed etc during remarking.
2169 // * Reference discovery is MT (see below).
2170 // * Reference discovery requires a barrier (see below).
2171 // * Reference processing may or may not be MT
2172 // (depending on the value of ParallelRefProcEnabled
2173 // and ParallelGCThreads).
2174 // * A full GC disables reference discovery by the CM
2175 // ref processor and abandons any entries on it's
2176 // discovered lists.
2177 //
2178 // * For the STW processor:
2179 // * Non MT discovery is enabled at the start of a full GC.
2180 // * Processing and enqueueing during a full GC is non-MT.
2181 // * During a full GC, references are processed after marking.
2182 //
2183 // * Discovery (may or may not be MT) is enabled at the start
2184 // of an incremental evacuation pause.
2185 // * References are processed near the end of a STW evacuation pause.
2186 // * For both types of GC:
2187 // * Discovery is atomic - i.e. not concurrent.
2188 // * Reference discovery will not need a barrier.
2190 SharedHeap::ref_processing_init();
2191 MemRegion mr = reserved_region();
2193 // Concurrent Mark ref processor
2194 _ref_processor_cm =
2195 new ReferenceProcessor(mr, // span
2196 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2197 // mt processing
2198 (int) ParallelGCThreads,
2199 // degree of mt processing
2200 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2201 // mt discovery
2202 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2203 // degree of mt discovery
2204 false,
2205 // Reference discovery is not atomic
2206 &_is_alive_closure_cm);
2207 // is alive closure
2208 // (for efficiency/performance)
2210 // STW ref processor
2211 _ref_processor_stw =
2212 new ReferenceProcessor(mr, // span
2213 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2214 // mt processing
2215 MAX2((int)ParallelGCThreads, 1),
2216 // degree of mt processing
2217 (ParallelGCThreads > 1),
2218 // mt discovery
2219 MAX2((int)ParallelGCThreads, 1),
2220 // degree of mt discovery
2221 true,
2222 // Reference discovery is atomic
2223 &_is_alive_closure_stw);
2224 // is alive closure
2225 // (for efficiency/performance)
2226 }
2228 size_t G1CollectedHeap::capacity() const {
2229 return _hrm.length() * HeapRegion::GrainBytes;
2230 }
2232 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2233 assert(!hr->continuesHumongous(), "pre-condition");
2234 hr->reset_gc_time_stamp();
2235 if (hr->startsHumongous()) {
2236 uint first_index = hr->hrm_index() + 1;
2237 uint last_index = hr->last_hc_index();
2238 for (uint i = first_index; i < last_index; i += 1) {
2239 HeapRegion* chr = region_at(i);
2240 assert(chr->continuesHumongous(), "sanity");
2241 chr->reset_gc_time_stamp();
2242 }
2243 }
2244 }
2246 #ifndef PRODUCT
2247 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2248 private:
2249 unsigned _gc_time_stamp;
2250 bool _failures;
2252 public:
2253 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2254 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2256 virtual bool doHeapRegion(HeapRegion* hr) {
2257 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2258 if (_gc_time_stamp != region_gc_time_stamp) {
2259 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2260 "expected %d", HR_FORMAT_PARAMS(hr),
2261 region_gc_time_stamp, _gc_time_stamp);
2262 _failures = true;
2263 }
2264 return false;
2265 }
2267 bool failures() { return _failures; }
2268 };
2270 void G1CollectedHeap::check_gc_time_stamps() {
2271 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2272 heap_region_iterate(&cl);
2273 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2274 }
2275 #endif // PRODUCT
2277 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2278 DirtyCardQueue* into_cset_dcq,
2279 bool concurrent,
2280 uint worker_i) {
2281 // Clean cards in the hot card cache
2282 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2283 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2285 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2286 size_t n_completed_buffers = 0;
2287 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2288 n_completed_buffers++;
2289 }
2290 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2291 dcqs.clear_n_completed_buffers();
2292 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2293 }
2296 // Computes the sum of the storage used by the various regions.
2297 size_t G1CollectedHeap::used() const {
2298 return _allocator->used();
2299 }
2301 size_t G1CollectedHeap::used_unlocked() const {
2302 return _allocator->used_unlocked();
2303 }
2305 class SumUsedClosure: public HeapRegionClosure {
2306 size_t _used;
2307 public:
2308 SumUsedClosure() : _used(0) {}
2309 bool doHeapRegion(HeapRegion* r) {
2310 if (!r->continuesHumongous()) {
2311 _used += r->used();
2312 }
2313 return false;
2314 }
2315 size_t result() { return _used; }
2316 };
2318 size_t G1CollectedHeap::recalculate_used() const {
2319 double recalculate_used_start = os::elapsedTime();
2321 SumUsedClosure blk;
2322 heap_region_iterate(&blk);
2324 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2325 return blk.result();
2326 }
2328 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2329 switch (cause) {
2330 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2331 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2332 case GCCause::_g1_humongous_allocation: return true;
2333 case GCCause::_update_allocation_context_stats_inc: return true;
2334 default: return false;
2335 }
2336 }
2338 #ifndef PRODUCT
2339 void G1CollectedHeap::allocate_dummy_regions() {
2340 // Let's fill up most of the region
2341 size_t word_size = HeapRegion::GrainWords - 1024;
2342 // And as a result the region we'll allocate will be humongous.
2343 guarantee(isHumongous(word_size), "sanity");
2345 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2346 // Let's use the existing mechanism for the allocation
2347 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2348 AllocationContext::system());
2349 if (dummy_obj != NULL) {
2350 MemRegion mr(dummy_obj, word_size);
2351 CollectedHeap::fill_with_object(mr);
2352 } else {
2353 // If we can't allocate once, we probably cannot allocate
2354 // again. Let's get out of the loop.
2355 break;
2356 }
2357 }
2358 }
2359 #endif // !PRODUCT
2361 void G1CollectedHeap::increment_old_marking_cycles_started() {
2362 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2363 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2364 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2365 _old_marking_cycles_started, _old_marking_cycles_completed));
2367 _old_marking_cycles_started++;
2368 }
2370 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2371 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2373 // We assume that if concurrent == true, then the caller is a
2374 // concurrent thread that was joined the Suspendible Thread
2375 // Set. If there's ever a cheap way to check this, we should add an
2376 // assert here.
2378 // Given that this method is called at the end of a Full GC or of a
2379 // concurrent cycle, and those can be nested (i.e., a Full GC can
2380 // interrupt a concurrent cycle), the number of full collections
2381 // completed should be either one (in the case where there was no
2382 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2383 // behind the number of full collections started.
2385 // This is the case for the inner caller, i.e. a Full GC.
2386 assert(concurrent ||
2387 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2388 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2389 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2390 "is inconsistent with _old_marking_cycles_completed = %u",
2391 _old_marking_cycles_started, _old_marking_cycles_completed));
2393 // This is the case for the outer caller, i.e. the concurrent cycle.
2394 assert(!concurrent ||
2395 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2396 err_msg("for outer caller (concurrent cycle): "
2397 "_old_marking_cycles_started = %u "
2398 "is inconsistent with _old_marking_cycles_completed = %u",
2399 _old_marking_cycles_started, _old_marking_cycles_completed));
2401 _old_marking_cycles_completed += 1;
2403 // We need to clear the "in_progress" flag in the CM thread before
2404 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2405 // is set) so that if a waiter requests another System.gc() it doesn't
2406 // incorrectly see that a marking cycle is still in progress.
2407 if (concurrent) {
2408 _cmThread->clear_in_progress();
2409 }
2411 // This notify_all() will ensure that a thread that called
2412 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2413 // and it's waiting for a full GC to finish will be woken up. It is
2414 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2415 FullGCCount_lock->notify_all();
2416 }
2418 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2419 _concurrent_cycle_started = true;
2420 _gc_timer_cm->register_gc_start(start_time);
2422 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2423 trace_heap_before_gc(_gc_tracer_cm);
2424 }
2426 void G1CollectedHeap::register_concurrent_cycle_end() {
2427 if (_concurrent_cycle_started) {
2428 if (_cm->has_aborted()) {
2429 _gc_tracer_cm->report_concurrent_mode_failure();
2430 }
2432 _gc_timer_cm->register_gc_end();
2433 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2435 // Clear state variables to prepare for the next concurrent cycle.
2436 _concurrent_cycle_started = false;
2437 _heap_summary_sent = false;
2438 }
2439 }
2441 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2442 if (_concurrent_cycle_started) {
2443 // This function can be called when:
2444 // the cleanup pause is run
2445 // the concurrent cycle is aborted before the cleanup pause.
2446 // the concurrent cycle is aborted after the cleanup pause,
2447 // but before the concurrent cycle end has been registered.
2448 // Make sure that we only send the heap information once.
2449 if (!_heap_summary_sent) {
2450 trace_heap_after_gc(_gc_tracer_cm);
2451 _heap_summary_sent = true;
2452 }
2453 }
2454 }
2456 G1YCType G1CollectedHeap::yc_type() {
2457 bool is_young = g1_policy()->gcs_are_young();
2458 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2459 bool is_during_mark = mark_in_progress();
2461 if (is_initial_mark) {
2462 return InitialMark;
2463 } else if (is_during_mark) {
2464 return DuringMark;
2465 } else if (is_young) {
2466 return Normal;
2467 } else {
2468 return Mixed;
2469 }
2470 }
2472 void G1CollectedHeap::collect(GCCause::Cause cause) {
2473 assert_heap_not_locked();
2475 uint gc_count_before;
2476 uint old_marking_count_before;
2477 uint full_gc_count_before;
2478 bool retry_gc;
2480 do {
2481 retry_gc = false;
2483 {
2484 MutexLocker ml(Heap_lock);
2486 // Read the GC count while holding the Heap_lock
2487 gc_count_before = total_collections();
2488 full_gc_count_before = total_full_collections();
2489 old_marking_count_before = _old_marking_cycles_started;
2490 }
2492 if (should_do_concurrent_full_gc(cause)) {
2493 // Schedule an initial-mark evacuation pause that will start a
2494 // concurrent cycle. We're setting word_size to 0 which means that
2495 // we are not requesting a post-GC allocation.
2496 VM_G1IncCollectionPause op(gc_count_before,
2497 0, /* word_size */
2498 true, /* should_initiate_conc_mark */
2499 g1_policy()->max_pause_time_ms(),
2500 cause);
2501 op.set_allocation_context(AllocationContext::current());
2503 VMThread::execute(&op);
2504 if (!op.pause_succeeded()) {
2505 if (old_marking_count_before == _old_marking_cycles_started) {
2506 retry_gc = op.should_retry_gc();
2507 } else {
2508 // A Full GC happened while we were trying to schedule the
2509 // initial-mark GC. No point in starting a new cycle given
2510 // that the whole heap was collected anyway.
2511 }
2513 if (retry_gc) {
2514 if (GC_locker::is_active_and_needs_gc()) {
2515 GC_locker::stall_until_clear();
2516 }
2517 }
2518 }
2519 } else {
2520 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2521 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2523 // Schedule a standard evacuation pause. We're setting word_size
2524 // to 0 which means that we are not requesting a post-GC allocation.
2525 VM_G1IncCollectionPause op(gc_count_before,
2526 0, /* word_size */
2527 false, /* should_initiate_conc_mark */
2528 g1_policy()->max_pause_time_ms(),
2529 cause);
2530 VMThread::execute(&op);
2531 } else {
2532 // Schedule a Full GC.
2533 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2534 VMThread::execute(&op);
2535 }
2536 }
2537 } while (retry_gc);
2538 }
2540 bool G1CollectedHeap::is_in(const void* p) const {
2541 if (_hrm.reserved().contains(p)) {
2542 // Given that we know that p is in the reserved space,
2543 // heap_region_containing_raw() should successfully
2544 // return the containing region.
2545 HeapRegion* hr = heap_region_containing_raw(p);
2546 return hr->is_in(p);
2547 } else {
2548 return false;
2549 }
2550 }
2552 #ifdef ASSERT
2553 bool G1CollectedHeap::is_in_exact(const void* p) const {
2554 bool contains = reserved_region().contains(p);
2555 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2556 if (contains && available) {
2557 return true;
2558 } else {
2559 return false;
2560 }
2561 }
2562 #endif
2564 // Iteration functions.
2566 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2568 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2569 ExtendedOopClosure* _cl;
2570 public:
2571 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2572 bool doHeapRegion(HeapRegion* r) {
2573 if (!r->continuesHumongous()) {
2574 r->oop_iterate(_cl);
2575 }
2576 return false;
2577 }
2578 };
2580 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2581 IterateOopClosureRegionClosure blk(cl);
2582 heap_region_iterate(&blk);
2583 }
2585 // Iterates an ObjectClosure over all objects within a HeapRegion.
2587 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2588 ObjectClosure* _cl;
2589 public:
2590 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2591 bool doHeapRegion(HeapRegion* r) {
2592 if (! r->continuesHumongous()) {
2593 r->object_iterate(_cl);
2594 }
2595 return false;
2596 }
2597 };
2599 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2600 IterateObjectClosureRegionClosure blk(cl);
2601 heap_region_iterate(&blk);
2602 }
2604 // Calls a SpaceClosure on a HeapRegion.
2606 class SpaceClosureRegionClosure: public HeapRegionClosure {
2607 SpaceClosure* _cl;
2608 public:
2609 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2610 bool doHeapRegion(HeapRegion* r) {
2611 _cl->do_space(r);
2612 return false;
2613 }
2614 };
2616 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2617 SpaceClosureRegionClosure blk(cl);
2618 heap_region_iterate(&blk);
2619 }
2621 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2622 _hrm.iterate(cl);
2623 }
2625 void
2626 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2627 uint worker_id,
2628 uint num_workers,
2629 jint claim_value) const {
2630 _hrm.par_iterate(cl, worker_id, num_workers, claim_value);
2631 }
2633 class ResetClaimValuesClosure: public HeapRegionClosure {
2634 public:
2635 bool doHeapRegion(HeapRegion* r) {
2636 r->set_claim_value(HeapRegion::InitialClaimValue);
2637 return false;
2638 }
2639 };
2641 void G1CollectedHeap::reset_heap_region_claim_values() {
2642 ResetClaimValuesClosure blk;
2643 heap_region_iterate(&blk);
2644 }
2646 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2647 ResetClaimValuesClosure blk;
2648 collection_set_iterate(&blk);
2649 }
2651 #ifdef ASSERT
2652 // This checks whether all regions in the heap have the correct claim
2653 // value. I also piggy-backed on this a check to ensure that the
2654 // humongous_start_region() information on "continues humongous"
2655 // regions is correct.
2657 class CheckClaimValuesClosure : public HeapRegionClosure {
2658 private:
2659 jint _claim_value;
2660 uint _failures;
2661 HeapRegion* _sh_region;
2663 public:
2664 CheckClaimValuesClosure(jint claim_value) :
2665 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2666 bool doHeapRegion(HeapRegion* r) {
2667 if (r->claim_value() != _claim_value) {
2668 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2669 "claim value = %d, should be %d",
2670 HR_FORMAT_PARAMS(r),
2671 r->claim_value(), _claim_value);
2672 ++_failures;
2673 }
2674 if (!r->isHumongous()) {
2675 _sh_region = NULL;
2676 } else if (r->startsHumongous()) {
2677 _sh_region = r;
2678 } else if (r->continuesHumongous()) {
2679 if (r->humongous_start_region() != _sh_region) {
2680 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2681 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2682 HR_FORMAT_PARAMS(r),
2683 r->humongous_start_region(),
2684 _sh_region);
2685 ++_failures;
2686 }
2687 }
2688 return false;
2689 }
2690 uint failures() { return _failures; }
2691 };
2693 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2694 CheckClaimValuesClosure cl(claim_value);
2695 heap_region_iterate(&cl);
2696 return cl.failures() == 0;
2697 }
2699 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2700 private:
2701 jint _claim_value;
2702 uint _failures;
2704 public:
2705 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2706 _claim_value(claim_value), _failures(0) { }
2708 uint failures() { return _failures; }
2710 bool doHeapRegion(HeapRegion* hr) {
2711 assert(hr->in_collection_set(), "how?");
2712 assert(!hr->isHumongous(), "H-region in CSet");
2713 if (hr->claim_value() != _claim_value) {
2714 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2715 "claim value = %d, should be %d",
2716 HR_FORMAT_PARAMS(hr),
2717 hr->claim_value(), _claim_value);
2718 _failures += 1;
2719 }
2720 return false;
2721 }
2722 };
2724 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2725 CheckClaimValuesInCSetHRClosure cl(claim_value);
2726 collection_set_iterate(&cl);
2727 return cl.failures() == 0;
2728 }
2729 #endif // ASSERT
2731 // Clear the cached CSet starting regions and (more importantly)
2732 // the time stamps. Called when we reset the GC time stamp.
2733 void G1CollectedHeap::clear_cset_start_regions() {
2734 assert(_worker_cset_start_region != NULL, "sanity");
2735 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2737 int n_queues = MAX2((int)ParallelGCThreads, 1);
2738 for (int i = 0; i < n_queues; i++) {
2739 _worker_cset_start_region[i] = NULL;
2740 _worker_cset_start_region_time_stamp[i] = 0;
2741 }
2742 }
2744 // Given the id of a worker, obtain or calculate a suitable
2745 // starting region for iterating over the current collection set.
2746 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2747 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2749 HeapRegion* result = NULL;
2750 unsigned gc_time_stamp = get_gc_time_stamp();
2752 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2753 // Cached starting region for current worker was set
2754 // during the current pause - so it's valid.
2755 // Note: the cached starting heap region may be NULL
2756 // (when the collection set is empty).
2757 result = _worker_cset_start_region[worker_i];
2758 assert(result == NULL || result->in_collection_set(), "sanity");
2759 return result;
2760 }
2762 // The cached entry was not valid so let's calculate
2763 // a suitable starting heap region for this worker.
2765 // We want the parallel threads to start their collection
2766 // set iteration at different collection set regions to
2767 // avoid contention.
2768 // If we have:
2769 // n collection set regions
2770 // p threads
2771 // Then thread t will start at region floor ((t * n) / p)
2773 result = g1_policy()->collection_set();
2774 if (G1CollectedHeap::use_parallel_gc_threads()) {
2775 uint cs_size = g1_policy()->cset_region_length();
2776 uint active_workers = workers()->active_workers();
2777 assert(UseDynamicNumberOfGCThreads ||
2778 active_workers == workers()->total_workers(),
2779 "Unless dynamic should use total workers");
2781 uint end_ind = (cs_size * worker_i) / active_workers;
2782 uint start_ind = 0;
2784 if (worker_i > 0 &&
2785 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2786 // Previous workers starting region is valid
2787 // so let's iterate from there
2788 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2789 result = _worker_cset_start_region[worker_i - 1];
2790 }
2792 for (uint i = start_ind; i < end_ind; i++) {
2793 result = result->next_in_collection_set();
2794 }
2795 }
2797 // Note: the calculated starting heap region may be NULL
2798 // (when the collection set is empty).
2799 assert(result == NULL || result->in_collection_set(), "sanity");
2800 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2801 "should be updated only once per pause");
2802 _worker_cset_start_region[worker_i] = result;
2803 OrderAccess::storestore();
2804 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2805 return result;
2806 }
2808 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2809 HeapRegion* r = g1_policy()->collection_set();
2810 while (r != NULL) {
2811 HeapRegion* next = r->next_in_collection_set();
2812 if (cl->doHeapRegion(r)) {
2813 cl->incomplete();
2814 return;
2815 }
2816 r = next;
2817 }
2818 }
2820 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2821 HeapRegionClosure *cl) {
2822 if (r == NULL) {
2823 // The CSet is empty so there's nothing to do.
2824 return;
2825 }
2827 assert(r->in_collection_set(),
2828 "Start region must be a member of the collection set.");
2829 HeapRegion* cur = r;
2830 while (cur != NULL) {
2831 HeapRegion* next = cur->next_in_collection_set();
2832 if (cl->doHeapRegion(cur) && false) {
2833 cl->incomplete();
2834 return;
2835 }
2836 cur = next;
2837 }
2838 cur = g1_policy()->collection_set();
2839 while (cur != r) {
2840 HeapRegion* next = cur->next_in_collection_set();
2841 if (cl->doHeapRegion(cur) && false) {
2842 cl->incomplete();
2843 return;
2844 }
2845 cur = next;
2846 }
2847 }
2849 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2850 HeapRegion* result = _hrm.next_region_in_heap(from);
2851 while (result != NULL && result->isHumongous()) {
2852 result = _hrm.next_region_in_heap(result);
2853 }
2854 return result;
2855 }
2857 Space* G1CollectedHeap::space_containing(const void* addr) const {
2858 return heap_region_containing(addr);
2859 }
2861 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2862 Space* sp = space_containing(addr);
2863 return sp->block_start(addr);
2864 }
2866 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2867 Space* sp = space_containing(addr);
2868 return sp->block_size(addr);
2869 }
2871 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2872 Space* sp = space_containing(addr);
2873 return sp->block_is_obj(addr);
2874 }
2876 bool G1CollectedHeap::supports_tlab_allocation() const {
2877 return true;
2878 }
2880 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2881 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2882 }
2884 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2885 return young_list()->eden_used_bytes();
2886 }
2888 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2889 // must be smaller than the humongous object limit.
2890 size_t G1CollectedHeap::max_tlab_size() const {
2891 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2892 }
2894 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2895 // Return the remaining space in the cur alloc region, but not less than
2896 // the min TLAB size.
2898 // Also, this value can be at most the humongous object threshold,
2899 // since we can't allow tlabs to grow big enough to accommodate
2900 // humongous objects.
2902 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2903 size_t max_tlab = max_tlab_size() * wordSize;
2904 if (hr == NULL) {
2905 return max_tlab;
2906 } else {
2907 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2908 }
2909 }
2911 size_t G1CollectedHeap::max_capacity() const {
2912 return _hrm.reserved().byte_size();
2913 }
2915 jlong G1CollectedHeap::millis_since_last_gc() {
2916 // assert(false, "NYI");
2917 return 0;
2918 }
2920 void G1CollectedHeap::prepare_for_verify() {
2921 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2922 ensure_parsability(false);
2923 }
2924 g1_rem_set()->prepare_for_verify();
2925 }
2927 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2928 VerifyOption vo) {
2929 switch (vo) {
2930 case VerifyOption_G1UsePrevMarking:
2931 return hr->obj_allocated_since_prev_marking(obj);
2932 case VerifyOption_G1UseNextMarking:
2933 return hr->obj_allocated_since_next_marking(obj);
2934 case VerifyOption_G1UseMarkWord:
2935 return false;
2936 default:
2937 ShouldNotReachHere();
2938 }
2939 return false; // keep some compilers happy
2940 }
2942 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2943 switch (vo) {
2944 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2945 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2946 case VerifyOption_G1UseMarkWord: return NULL;
2947 default: ShouldNotReachHere();
2948 }
2949 return NULL; // keep some compilers happy
2950 }
2952 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2953 switch (vo) {
2954 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2955 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2956 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2957 default: ShouldNotReachHere();
2958 }
2959 return false; // keep some compilers happy
2960 }
2962 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2963 switch (vo) {
2964 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2965 case VerifyOption_G1UseNextMarking: return "NTAMS";
2966 case VerifyOption_G1UseMarkWord: return "NONE";
2967 default: ShouldNotReachHere();
2968 }
2969 return NULL; // keep some compilers happy
2970 }
2972 class VerifyRootsClosure: public OopClosure {
2973 private:
2974 G1CollectedHeap* _g1h;
2975 VerifyOption _vo;
2976 bool _failures;
2977 public:
2978 // _vo == UsePrevMarking -> use "prev" marking information,
2979 // _vo == UseNextMarking -> use "next" marking information,
2980 // _vo == UseMarkWord -> use mark word from object header.
2981 VerifyRootsClosure(VerifyOption vo) :
2982 _g1h(G1CollectedHeap::heap()),
2983 _vo(vo),
2984 _failures(false) { }
2986 bool failures() { return _failures; }
2988 template <class T> void do_oop_nv(T* p) {
2989 T heap_oop = oopDesc::load_heap_oop(p);
2990 if (!oopDesc::is_null(heap_oop)) {
2991 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2992 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2993 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2994 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2995 if (_vo == VerifyOption_G1UseMarkWord) {
2996 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2997 }
2998 obj->print_on(gclog_or_tty);
2999 _failures = true;
3000 }
3001 }
3002 }
3004 void do_oop(oop* p) { do_oop_nv(p); }
3005 void do_oop(narrowOop* p) { do_oop_nv(p); }
3006 };
3008 class G1VerifyCodeRootOopClosure: public OopClosure {
3009 G1CollectedHeap* _g1h;
3010 OopClosure* _root_cl;
3011 nmethod* _nm;
3012 VerifyOption _vo;
3013 bool _failures;
3015 template <class T> void do_oop_work(T* p) {
3016 // First verify that this root is live
3017 _root_cl->do_oop(p);
3019 if (!G1VerifyHeapRegionCodeRoots) {
3020 // We're not verifying the code roots attached to heap region.
3021 return;
3022 }
3024 // Don't check the code roots during marking verification in a full GC
3025 if (_vo == VerifyOption_G1UseMarkWord) {
3026 return;
3027 }
3029 // Now verify that the current nmethod (which contains p) is
3030 // in the code root list of the heap region containing the
3031 // object referenced by p.
3033 T heap_oop = oopDesc::load_heap_oop(p);
3034 if (!oopDesc::is_null(heap_oop)) {
3035 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3037 // Now fetch the region containing the object
3038 HeapRegion* hr = _g1h->heap_region_containing(obj);
3039 HeapRegionRemSet* hrrs = hr->rem_set();
3040 // Verify that the strong code root list for this region
3041 // contains the nmethod
3042 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3043 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3044 "from nmethod "PTR_FORMAT" not in strong "
3045 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3046 p, _nm, hr->bottom(), hr->end());
3047 _failures = true;
3048 }
3049 }
3050 }
3052 public:
3053 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3054 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3056 void do_oop(oop* p) { do_oop_work(p); }
3057 void do_oop(narrowOop* p) { do_oop_work(p); }
3059 void set_nmethod(nmethod* nm) { _nm = nm; }
3060 bool failures() { return _failures; }
3061 };
3063 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3064 G1VerifyCodeRootOopClosure* _oop_cl;
3066 public:
3067 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3068 _oop_cl(oop_cl) {}
3070 void do_code_blob(CodeBlob* cb) {
3071 nmethod* nm = cb->as_nmethod_or_null();
3072 if (nm != NULL) {
3073 _oop_cl->set_nmethod(nm);
3074 nm->oops_do(_oop_cl);
3075 }
3076 }
3077 };
3079 class YoungRefCounterClosure : public OopClosure {
3080 G1CollectedHeap* _g1h;
3081 int _count;
3082 public:
3083 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3084 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3085 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3087 int count() { return _count; }
3088 void reset_count() { _count = 0; };
3089 };
3091 class VerifyKlassClosure: public KlassClosure {
3092 YoungRefCounterClosure _young_ref_counter_closure;
3093 OopClosure *_oop_closure;
3094 public:
3095 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3096 void do_klass(Klass* k) {
3097 k->oops_do(_oop_closure);
3099 _young_ref_counter_closure.reset_count();
3100 k->oops_do(&_young_ref_counter_closure);
3101 if (_young_ref_counter_closure.count() > 0) {
3102 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3103 }
3104 }
3105 };
3107 class VerifyLivenessOopClosure: public OopClosure {
3108 G1CollectedHeap* _g1h;
3109 VerifyOption _vo;
3110 public:
3111 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3112 _g1h(g1h), _vo(vo)
3113 { }
3114 void do_oop(narrowOop *p) { do_oop_work(p); }
3115 void do_oop( oop *p) { do_oop_work(p); }
3117 template <class T> void do_oop_work(T *p) {
3118 oop obj = oopDesc::load_decode_heap_oop(p);
3119 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3120 "Dead object referenced by a not dead object");
3121 }
3122 };
3124 class VerifyObjsInRegionClosure: public ObjectClosure {
3125 private:
3126 G1CollectedHeap* _g1h;
3127 size_t _live_bytes;
3128 HeapRegion *_hr;
3129 VerifyOption _vo;
3130 public:
3131 // _vo == UsePrevMarking -> use "prev" marking information,
3132 // _vo == UseNextMarking -> use "next" marking information,
3133 // _vo == UseMarkWord -> use mark word from object header.
3134 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3135 : _live_bytes(0), _hr(hr), _vo(vo) {
3136 _g1h = G1CollectedHeap::heap();
3137 }
3138 void do_object(oop o) {
3139 VerifyLivenessOopClosure isLive(_g1h, _vo);
3140 assert(o != NULL, "Huh?");
3141 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3142 // If the object is alive according to the mark word,
3143 // then verify that the marking information agrees.
3144 // Note we can't verify the contra-positive of the
3145 // above: if the object is dead (according to the mark
3146 // word), it may not be marked, or may have been marked
3147 // but has since became dead, or may have been allocated
3148 // since the last marking.
3149 if (_vo == VerifyOption_G1UseMarkWord) {
3150 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3151 }
3153 o->oop_iterate_no_header(&isLive);
3154 if (!_hr->obj_allocated_since_prev_marking(o)) {
3155 size_t obj_size = o->size(); // Make sure we don't overflow
3156 _live_bytes += (obj_size * HeapWordSize);
3157 }
3158 }
3159 }
3160 size_t live_bytes() { return _live_bytes; }
3161 };
3163 class PrintObjsInRegionClosure : public ObjectClosure {
3164 HeapRegion *_hr;
3165 G1CollectedHeap *_g1;
3166 public:
3167 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3168 _g1 = G1CollectedHeap::heap();
3169 };
3171 void do_object(oop o) {
3172 if (o != NULL) {
3173 HeapWord *start = (HeapWord *) o;
3174 size_t word_sz = o->size();
3175 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3176 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3177 (void*) o, word_sz,
3178 _g1->isMarkedPrev(o),
3179 _g1->isMarkedNext(o),
3180 _hr->obj_allocated_since_prev_marking(o));
3181 HeapWord *end = start + word_sz;
3182 HeapWord *cur;
3183 int *val;
3184 for (cur = start; cur < end; cur++) {
3185 val = (int *) cur;
3186 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3187 }
3188 }
3189 }
3190 };
3192 class VerifyRegionClosure: public HeapRegionClosure {
3193 private:
3194 bool _par;
3195 VerifyOption _vo;
3196 bool _failures;
3197 public:
3198 // _vo == UsePrevMarking -> use "prev" marking information,
3199 // _vo == UseNextMarking -> use "next" marking information,
3200 // _vo == UseMarkWord -> use mark word from object header.
3201 VerifyRegionClosure(bool par, VerifyOption vo)
3202 : _par(par),
3203 _vo(vo),
3204 _failures(false) {}
3206 bool failures() {
3207 return _failures;
3208 }
3210 bool doHeapRegion(HeapRegion* r) {
3211 if (!r->continuesHumongous()) {
3212 bool failures = false;
3213 r->verify(_vo, &failures);
3214 if (failures) {
3215 _failures = true;
3216 } else {
3217 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3218 r->object_iterate(¬_dead_yet_cl);
3219 if (_vo != VerifyOption_G1UseNextMarking) {
3220 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3221 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3222 "max_live_bytes "SIZE_FORMAT" "
3223 "< calculated "SIZE_FORMAT,
3224 r->bottom(), r->end(),
3225 r->max_live_bytes(),
3226 not_dead_yet_cl.live_bytes());
3227 _failures = true;
3228 }
3229 } else {
3230 // When vo == UseNextMarking we cannot currently do a sanity
3231 // check on the live bytes as the calculation has not been
3232 // finalized yet.
3233 }
3234 }
3235 }
3236 return false; // stop the region iteration if we hit a failure
3237 }
3238 };
3240 // This is the task used for parallel verification of the heap regions
3242 class G1ParVerifyTask: public AbstractGangTask {
3243 private:
3244 G1CollectedHeap* _g1h;
3245 VerifyOption _vo;
3246 bool _failures;
3248 public:
3249 // _vo == UsePrevMarking -> use "prev" marking information,
3250 // _vo == UseNextMarking -> use "next" marking information,
3251 // _vo == UseMarkWord -> use mark word from object header.
3252 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3253 AbstractGangTask("Parallel verify task"),
3254 _g1h(g1h),
3255 _vo(vo),
3256 _failures(false) { }
3258 bool failures() {
3259 return _failures;
3260 }
3262 void work(uint worker_id) {
3263 HandleMark hm;
3264 VerifyRegionClosure blk(true, _vo);
3265 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3266 _g1h->workers()->active_workers(),
3267 HeapRegion::ParVerifyClaimValue);
3268 if (blk.failures()) {
3269 _failures = true;
3270 }
3271 }
3272 };
3274 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3275 if (SafepointSynchronize::is_at_safepoint()) {
3276 assert(Thread::current()->is_VM_thread(),
3277 "Expected to be executed serially by the VM thread at this point");
3279 if (!silent) { gclog_or_tty->print("Roots "); }
3280 VerifyRootsClosure rootsCl(vo);
3281 VerifyKlassClosure klassCl(this, &rootsCl);
3282 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3284 // We apply the relevant closures to all the oops in the
3285 // system dictionary, class loader data graph, the string table
3286 // and the nmethods in the code cache.
3287 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3288 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3290 {
3291 G1RootProcessor root_processor(this);
3292 root_processor.process_all_roots(&rootsCl,
3293 &cldCl,
3294 &blobsCl);
3295 }
3297 bool failures = rootsCl.failures() || codeRootsCl.failures();
3299 if (vo != VerifyOption_G1UseMarkWord) {
3300 // If we're verifying during a full GC then the region sets
3301 // will have been torn down at the start of the GC. Therefore
3302 // verifying the region sets will fail. So we only verify
3303 // the region sets when not in a full GC.
3304 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3305 verify_region_sets();
3306 }
3308 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3309 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3310 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3311 "sanity check");
3313 G1ParVerifyTask task(this, vo);
3314 assert(UseDynamicNumberOfGCThreads ||
3315 workers()->active_workers() == workers()->total_workers(),
3316 "If not dynamic should be using all the workers");
3317 int n_workers = workers()->active_workers();
3318 set_par_threads(n_workers);
3319 workers()->run_task(&task);
3320 set_par_threads(0);
3321 if (task.failures()) {
3322 failures = true;
3323 }
3325 // Checks that the expected amount of parallel work was done.
3326 // The implication is that n_workers is > 0.
3327 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3328 "sanity check");
3330 reset_heap_region_claim_values();
3332 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3333 "sanity check");
3334 } else {
3335 VerifyRegionClosure blk(false, vo);
3336 heap_region_iterate(&blk);
3337 if (blk.failures()) {
3338 failures = true;
3339 }
3340 }
3341 if (!silent) gclog_or_tty->print("RemSet ");
3342 rem_set()->verify();
3344 if (G1StringDedup::is_enabled()) {
3345 if (!silent) gclog_or_tty->print("StrDedup ");
3346 G1StringDedup::verify();
3347 }
3349 if (failures) {
3350 gclog_or_tty->print_cr("Heap:");
3351 // It helps to have the per-region information in the output to
3352 // help us track down what went wrong. This is why we call
3353 // print_extended_on() instead of print_on().
3354 print_extended_on(gclog_or_tty);
3355 gclog_or_tty->cr();
3356 #ifndef PRODUCT
3357 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3358 concurrent_mark()->print_reachable("at-verification-failure",
3359 vo, false /* all */);
3360 }
3361 #endif
3362 gclog_or_tty->flush();
3363 }
3364 guarantee(!failures, "there should not have been any failures");
3365 } else {
3366 if (!silent) {
3367 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3368 if (G1StringDedup::is_enabled()) {
3369 gclog_or_tty->print(", StrDedup");
3370 }
3371 gclog_or_tty->print(") ");
3372 }
3373 }
3374 }
3376 void G1CollectedHeap::verify(bool silent) {
3377 verify(silent, VerifyOption_G1UsePrevMarking);
3378 }
3380 double G1CollectedHeap::verify(bool guard, const char* msg) {
3381 double verify_time_ms = 0.0;
3383 if (guard && total_collections() >= VerifyGCStartAt) {
3384 double verify_start = os::elapsedTime();
3385 HandleMark hm; // Discard invalid handles created during verification
3386 prepare_for_verify();
3387 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3388 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3389 }
3391 return verify_time_ms;
3392 }
3394 void G1CollectedHeap::verify_before_gc() {
3395 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3396 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3397 }
3399 void G1CollectedHeap::verify_after_gc() {
3400 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3401 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3402 }
3404 class PrintRegionClosure: public HeapRegionClosure {
3405 outputStream* _st;
3406 public:
3407 PrintRegionClosure(outputStream* st) : _st(st) {}
3408 bool doHeapRegion(HeapRegion* r) {
3409 r->print_on(_st);
3410 return false;
3411 }
3412 };
3414 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3415 const HeapRegion* hr,
3416 const VerifyOption vo) const {
3417 switch (vo) {
3418 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3419 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3420 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3421 default: ShouldNotReachHere();
3422 }
3423 return false; // keep some compilers happy
3424 }
3426 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3427 const VerifyOption vo) const {
3428 switch (vo) {
3429 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3430 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3431 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3432 default: ShouldNotReachHere();
3433 }
3434 return false; // keep some compilers happy
3435 }
3437 void G1CollectedHeap::print_on(outputStream* st) const {
3438 st->print(" %-20s", "garbage-first heap");
3439 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3440 capacity()/K, used_unlocked()/K);
3441 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3442 _hrm.reserved().start(),
3443 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3444 _hrm.reserved().end());
3445 st->cr();
3446 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3447 uint young_regions = _young_list->length();
3448 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3449 (size_t) young_regions * HeapRegion::GrainBytes / K);
3450 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3451 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3452 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3453 st->cr();
3454 MetaspaceAux::print_on(st);
3455 }
3457 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3458 print_on(st);
3460 // Print the per-region information.
3461 st->cr();
3462 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3463 "HS=humongous(starts), HC=humongous(continues), "
3464 "CS=collection set, F=free, TS=gc time stamp, "
3465 "PTAMS=previous top-at-mark-start, "
3466 "NTAMS=next top-at-mark-start)");
3467 PrintRegionClosure blk(st);
3468 heap_region_iterate(&blk);
3469 }
3471 void G1CollectedHeap::print_on_error(outputStream* st) const {
3472 this->CollectedHeap::print_on_error(st);
3474 if (_cm != NULL) {
3475 st->cr();
3476 _cm->print_on_error(st);
3477 }
3478 }
3480 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3481 if (G1CollectedHeap::use_parallel_gc_threads()) {
3482 workers()->print_worker_threads_on(st);
3483 }
3484 _cmThread->print_on(st);
3485 st->cr();
3486 _cm->print_worker_threads_on(st);
3487 _cg1r->print_worker_threads_on(st);
3488 if (G1StringDedup::is_enabled()) {
3489 G1StringDedup::print_worker_threads_on(st);
3490 }
3491 }
3493 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3494 if (G1CollectedHeap::use_parallel_gc_threads()) {
3495 workers()->threads_do(tc);
3496 }
3497 tc->do_thread(_cmThread);
3498 _cg1r->threads_do(tc);
3499 if (G1StringDedup::is_enabled()) {
3500 G1StringDedup::threads_do(tc);
3501 }
3502 }
3504 void G1CollectedHeap::print_tracing_info() const {
3505 // We'll overload this to mean "trace GC pause statistics."
3506 if (TraceGen0Time || TraceGen1Time) {
3507 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3508 // to that.
3509 g1_policy()->print_tracing_info();
3510 }
3511 if (G1SummarizeRSetStats) {
3512 g1_rem_set()->print_summary_info();
3513 }
3514 if (G1SummarizeConcMark) {
3515 concurrent_mark()->print_summary_info();
3516 }
3517 g1_policy()->print_yg_surv_rate_info();
3518 SpecializationStats::print();
3519 }
3521 #ifndef PRODUCT
3522 // Helpful for debugging RSet issues.
3524 class PrintRSetsClosure : public HeapRegionClosure {
3525 private:
3526 const char* _msg;
3527 size_t _occupied_sum;
3529 public:
3530 bool doHeapRegion(HeapRegion* r) {
3531 HeapRegionRemSet* hrrs = r->rem_set();
3532 size_t occupied = hrrs->occupied();
3533 _occupied_sum += occupied;
3535 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3536 HR_FORMAT_PARAMS(r));
3537 if (occupied == 0) {
3538 gclog_or_tty->print_cr(" RSet is empty");
3539 } else {
3540 hrrs->print();
3541 }
3542 gclog_or_tty->print_cr("----------");
3543 return false;
3544 }
3546 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3547 gclog_or_tty->cr();
3548 gclog_or_tty->print_cr("========================================");
3549 gclog_or_tty->print_cr("%s", msg);
3550 gclog_or_tty->cr();
3551 }
3553 ~PrintRSetsClosure() {
3554 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3555 gclog_or_tty->print_cr("========================================");
3556 gclog_or_tty->cr();
3557 }
3558 };
3560 void G1CollectedHeap::print_cset_rsets() {
3561 PrintRSetsClosure cl("Printing CSet RSets");
3562 collection_set_iterate(&cl);
3563 }
3565 void G1CollectedHeap::print_all_rsets() {
3566 PrintRSetsClosure cl("Printing All RSets");;
3567 heap_region_iterate(&cl);
3568 }
3569 #endif // PRODUCT
3571 G1CollectedHeap* G1CollectedHeap::heap() {
3572 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3573 "not a garbage-first heap");
3574 return _g1h;
3575 }
3577 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3578 // always_do_update_barrier = false;
3579 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3580 // Fill TLAB's and such
3581 accumulate_statistics_all_tlabs();
3582 ensure_parsability(true);
3584 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3585 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3586 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3587 }
3588 }
3590 void G1CollectedHeap::gc_epilogue(bool full) {
3592 if (G1SummarizeRSetStats &&
3593 (G1SummarizeRSetStatsPeriod > 0) &&
3594 // we are at the end of the GC. Total collections has already been increased.
3595 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3596 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3597 }
3599 // FIXME: what is this about?
3600 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3601 // is set.
3602 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3603 "derived pointer present"));
3604 // always_do_update_barrier = true;
3606 resize_all_tlabs();
3607 allocation_context_stats().update(full);
3609 // We have just completed a GC. Update the soft reference
3610 // policy with the new heap occupancy
3611 Universe::update_heap_info_at_gc();
3612 }
3614 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3615 uint gc_count_before,
3616 bool* succeeded,
3617 GCCause::Cause gc_cause) {
3618 assert_heap_not_locked_and_not_at_safepoint();
3619 g1_policy()->record_stop_world_start();
3620 VM_G1IncCollectionPause op(gc_count_before,
3621 word_size,
3622 false, /* should_initiate_conc_mark */
3623 g1_policy()->max_pause_time_ms(),
3624 gc_cause);
3626 op.set_allocation_context(AllocationContext::current());
3627 VMThread::execute(&op);
3629 HeapWord* result = op.result();
3630 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3631 assert(result == NULL || ret_succeeded,
3632 "the result should be NULL if the VM did not succeed");
3633 *succeeded = ret_succeeded;
3635 assert_heap_not_locked();
3636 return result;
3637 }
3639 void
3640 G1CollectedHeap::doConcurrentMark() {
3641 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3642 if (!_cmThread->in_progress()) {
3643 _cmThread->set_started();
3644 CGC_lock->notify();
3645 }
3646 }
3648 size_t G1CollectedHeap::pending_card_num() {
3649 size_t extra_cards = 0;
3650 JavaThread *curr = Threads::first();
3651 while (curr != NULL) {
3652 DirtyCardQueue& dcq = curr->dirty_card_queue();
3653 extra_cards += dcq.size();
3654 curr = curr->next();
3655 }
3656 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3657 size_t buffer_size = dcqs.buffer_size();
3658 size_t buffer_num = dcqs.completed_buffers_num();
3660 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3661 // in bytes - not the number of 'entries'. We need to convert
3662 // into a number of cards.
3663 return (buffer_size * buffer_num + extra_cards) / oopSize;
3664 }
3666 size_t G1CollectedHeap::cards_scanned() {
3667 return g1_rem_set()->cardsScanned();
3668 }
3670 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3671 private:
3672 size_t _total_humongous;
3673 size_t _candidate_humongous;
3675 DirtyCardQueue _dcq;
3677 // We don't nominate objects with many remembered set entries, on
3678 // the assumption that such objects are likely still live.
3679 bool is_remset_small(HeapRegion* region) const {
3680 HeapRegionRemSet* const rset = region->rem_set();
3681 return G1EagerReclaimHumongousObjectsWithStaleRefs
3682 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3683 : rset->is_empty();
3684 }
3686 bool is_typeArray_region(HeapRegion* region) const {
3687 return oop(region->bottom())->is_typeArray();
3688 }
3690 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3691 assert(region->startsHumongous(), "Must start a humongous object");
3693 // Candidate selection must satisfy the following constraints
3694 // while concurrent marking is in progress:
3695 //
3696 // * In order to maintain SATB invariants, an object must not be
3697 // reclaimed if it was allocated before the start of marking and
3698 // has not had its references scanned. Such an object must have
3699 // its references (including type metadata) scanned to ensure no
3700 // live objects are missed by the marking process. Objects
3701 // allocated after the start of concurrent marking don't need to
3702 // be scanned.
3703 //
3704 // * An object must not be reclaimed if it is on the concurrent
3705 // mark stack. Objects allocated after the start of concurrent
3706 // marking are never pushed on the mark stack.
3707 //
3708 // Nominating only objects allocated after the start of concurrent
3709 // marking is sufficient to meet both constraints. This may miss
3710 // some objects that satisfy the constraints, but the marking data
3711 // structures don't support efficiently performing the needed
3712 // additional tests or scrubbing of the mark stack.
3713 //
3714 // However, we presently only nominate is_typeArray() objects.
3715 // A humongous object containing references induces remembered
3716 // set entries on other regions. In order to reclaim such an
3717 // object, those remembered sets would need to be cleaned up.
3718 //
3719 // We also treat is_typeArray() objects specially, allowing them
3720 // to be reclaimed even if allocated before the start of
3721 // concurrent mark. For this we rely on mark stack insertion to
3722 // exclude is_typeArray() objects, preventing reclaiming an object
3723 // that is in the mark stack. We also rely on the metadata for
3724 // such objects to be built-in and so ensured to be kept live.
3725 // Frequent allocation and drop of large binary blobs is an
3726 // important use case for eager reclaim, and this special handling
3727 // may reduce needed headroom.
3729 return is_typeArray_region(region) && is_remset_small(region);
3730 }
3732 public:
3733 RegisterHumongousWithInCSetFastTestClosure()
3734 : _total_humongous(0),
3735 _candidate_humongous(0),
3736 _dcq(&JavaThread::dirty_card_queue_set()) {
3737 }
3739 virtual bool doHeapRegion(HeapRegion* r) {
3740 if (!r->startsHumongous()) {
3741 return false;
3742 }
3743 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3745 bool is_candidate = humongous_region_is_candidate(g1h, r);
3746 uint rindex = r->hrm_index();
3747 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3748 if (is_candidate) {
3749 _candidate_humongous++;
3750 g1h->register_humongous_region_with_in_cset_fast_test(rindex);
3751 // Is_candidate already filters out humongous object with large remembered sets.
3752 // If we have a humongous object with a few remembered sets, we simply flush these
3753 // remembered set entries into the DCQS. That will result in automatic
3754 // re-evaluation of their remembered set entries during the following evacuation
3755 // phase.
3756 if (!r->rem_set()->is_empty()) {
3757 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3758 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3759 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3760 HeapRegionRemSetIterator hrrs(r->rem_set());
3761 size_t card_index;
3762 while (hrrs.has_next(card_index)) {
3763 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3764 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3765 *card_ptr = CardTableModRefBS::dirty_card_val();
3766 _dcq.enqueue(card_ptr);
3767 }
3768 }
3769 r->rem_set()->clear_locked();
3770 }
3771 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3772 }
3773 _total_humongous++;
3775 return false;
3776 }
3778 size_t total_humongous() const { return _total_humongous; }
3779 size_t candidate_humongous() const { return _candidate_humongous; }
3781 void flush_rem_set_entries() { _dcq.flush(); }
3782 };
3784 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3785 if (!G1EagerReclaimHumongousObjects) {
3786 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3787 return;
3788 }
3789 double time = os::elapsed_counter();
3791 // Collect reclaim candidate information and register candidates with cset.
3792 RegisterHumongousWithInCSetFastTestClosure cl;
3793 heap_region_iterate(&cl);
3795 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3796 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3797 cl.total_humongous(),
3798 cl.candidate_humongous());
3799 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3801 // Finally flush all remembered set entries to re-check into the global DCQS.
3802 cl.flush_rem_set_entries();
3803 }
3805 void
3806 G1CollectedHeap::setup_surviving_young_words() {
3807 assert(_surviving_young_words == NULL, "pre-condition");
3808 uint array_length = g1_policy()->young_cset_region_length();
3809 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3810 if (_surviving_young_words == NULL) {
3811 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3812 "Not enough space for young surv words summary.");
3813 }
3814 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3815 #ifdef ASSERT
3816 for (uint i = 0; i < array_length; ++i) {
3817 assert( _surviving_young_words[i] == 0, "memset above" );
3818 }
3819 #endif // !ASSERT
3820 }
3822 void
3823 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3824 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3825 uint array_length = g1_policy()->young_cset_region_length();
3826 for (uint i = 0; i < array_length; ++i) {
3827 _surviving_young_words[i] += surv_young_words[i];
3828 }
3829 }
3831 void
3832 G1CollectedHeap::cleanup_surviving_young_words() {
3833 guarantee( _surviving_young_words != NULL, "pre-condition" );
3834 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3835 _surviving_young_words = NULL;
3836 }
3838 #ifdef ASSERT
3839 class VerifyCSetClosure: public HeapRegionClosure {
3840 public:
3841 bool doHeapRegion(HeapRegion* hr) {
3842 // Here we check that the CSet region's RSet is ready for parallel
3843 // iteration. The fields that we'll verify are only manipulated
3844 // when the region is part of a CSet and is collected. Afterwards,
3845 // we reset these fields when we clear the region's RSet (when the
3846 // region is freed) so they are ready when the region is
3847 // re-allocated. The only exception to this is if there's an
3848 // evacuation failure and instead of freeing the region we leave
3849 // it in the heap. In that case, we reset these fields during
3850 // evacuation failure handling.
3851 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3853 // Here's a good place to add any other checks we'd like to
3854 // perform on CSet regions.
3855 return false;
3856 }
3857 };
3858 #endif // ASSERT
3860 #if TASKQUEUE_STATS
3861 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3862 st->print_raw_cr("GC Task Stats");
3863 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3864 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3865 }
3867 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3868 print_taskqueue_stats_hdr(st);
3870 TaskQueueStats totals;
3871 const int n = workers() != NULL ? workers()->total_workers() : 1;
3872 for (int i = 0; i < n; ++i) {
3873 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3874 totals += task_queue(i)->stats;
3875 }
3876 st->print_raw("tot "); totals.print(st); st->cr();
3878 DEBUG_ONLY(totals.verify());
3879 }
3881 void G1CollectedHeap::reset_taskqueue_stats() {
3882 const int n = workers() != NULL ? workers()->total_workers() : 1;
3883 for (int i = 0; i < n; ++i) {
3884 task_queue(i)->stats.reset();
3885 }
3886 }
3887 #endif // TASKQUEUE_STATS
3889 void G1CollectedHeap::log_gc_header() {
3890 if (!G1Log::fine()) {
3891 return;
3892 }
3894 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3896 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3897 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3898 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3900 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3901 }
3903 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3904 if (!G1Log::fine()) {
3905 return;
3906 }
3908 if (G1Log::finer()) {
3909 if (evacuation_failed()) {
3910 gclog_or_tty->print(" (to-space exhausted)");
3911 }
3912 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3913 g1_policy()->phase_times()->note_gc_end();
3914 g1_policy()->phase_times()->print(pause_time_sec);
3915 g1_policy()->print_detailed_heap_transition();
3916 } else {
3917 if (evacuation_failed()) {
3918 gclog_or_tty->print("--");
3919 }
3920 g1_policy()->print_heap_transition();
3921 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3922 }
3923 gclog_or_tty->flush();
3924 }
3926 bool
3927 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3928 assert_at_safepoint(true /* should_be_vm_thread */);
3929 guarantee(!is_gc_active(), "collection is not reentrant");
3931 if (GC_locker::check_active_before_gc()) {
3932 return false;
3933 }
3935 _gc_timer_stw->register_gc_start();
3937 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3939 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3940 ResourceMark rm;
3942 print_heap_before_gc();
3943 trace_heap_before_gc(_gc_tracer_stw);
3945 verify_region_sets_optional();
3946 verify_dirty_young_regions();
3948 // This call will decide whether this pause is an initial-mark
3949 // pause. If it is, during_initial_mark_pause() will return true
3950 // for the duration of this pause.
3951 g1_policy()->decide_on_conc_mark_initiation();
3953 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3954 assert(!g1_policy()->during_initial_mark_pause() ||
3955 g1_policy()->gcs_are_young(), "sanity");
3957 // We also do not allow mixed GCs during marking.
3958 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3960 // Record whether this pause is an initial mark. When the current
3961 // thread has completed its logging output and it's safe to signal
3962 // the CM thread, the flag's value in the policy has been reset.
3963 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3965 // Inner scope for scope based logging, timers, and stats collection
3966 {
3967 EvacuationInfo evacuation_info;
3969 if (g1_policy()->during_initial_mark_pause()) {
3970 // We are about to start a marking cycle, so we increment the
3971 // full collection counter.
3972 increment_old_marking_cycles_started();
3973 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3974 }
3976 _gc_tracer_stw->report_yc_type(yc_type());
3978 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3980 uint active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3981 workers()->active_workers() : 1);
3982 double pause_start_sec = os::elapsedTime();
3983 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3984 log_gc_header();
3986 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3987 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3989 // If the secondary_free_list is not empty, append it to the
3990 // free_list. No need to wait for the cleanup operation to finish;
3991 // the region allocation code will check the secondary_free_list
3992 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3993 // set, skip this step so that the region allocation code has to
3994 // get entries from the secondary_free_list.
3995 if (!G1StressConcRegionFreeing) {
3996 append_secondary_free_list_if_not_empty_with_lock();
3997 }
3999 assert(check_young_list_well_formed(), "young list should be well formed");
4000 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
4001 "sanity check");
4003 // Don't dynamically change the number of GC threads this early. A value of
4004 // 0 is used to indicate serial work. When parallel work is done,
4005 // it will be set.
4007 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4008 IsGCActiveMark x;
4010 gc_prologue(false);
4011 increment_total_collections(false /* full gc */);
4012 increment_gc_time_stamp();
4014 verify_before_gc();
4015 check_bitmaps("GC Start");
4017 COMPILER2_PRESENT(DerivedPointerTable::clear());
4019 // Please see comment in g1CollectedHeap.hpp and
4020 // G1CollectedHeap::ref_processing_init() to see how
4021 // reference processing currently works in G1.
4023 // Enable discovery in the STW reference processor
4024 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4025 true /*verify_no_refs*/);
4027 {
4028 // We want to temporarily turn off discovery by the
4029 // CM ref processor, if necessary, and turn it back on
4030 // on again later if we do. Using a scoped
4031 // NoRefDiscovery object will do this.
4032 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4034 // Forget the current alloc region (we might even choose it to be part
4035 // of the collection set!).
4036 _allocator->release_mutator_alloc_region();
4038 // We should call this after we retire the mutator alloc
4039 // region(s) so that all the ALLOC / RETIRE events are generated
4040 // before the start GC event.
4041 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4043 // This timing is only used by the ergonomics to handle our pause target.
4044 // It is unclear why this should not include the full pause. We will
4045 // investigate this in CR 7178365.
4046 //
4047 // Preserving the old comment here if that helps the investigation:
4048 //
4049 // The elapsed time induced by the start time below deliberately elides
4050 // the possible verification above.
4051 double sample_start_time_sec = os::elapsedTime();
4053 #if YOUNG_LIST_VERBOSE
4054 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4055 _young_list->print();
4056 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4057 #endif // YOUNG_LIST_VERBOSE
4059 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4061 double scan_wait_start = os::elapsedTime();
4062 // We have to wait until the CM threads finish scanning the
4063 // root regions as it's the only way to ensure that all the
4064 // objects on them have been correctly scanned before we start
4065 // moving them during the GC.
4066 bool waited = _cm->root_regions()->wait_until_scan_finished();
4067 double wait_time_ms = 0.0;
4068 if (waited) {
4069 double scan_wait_end = os::elapsedTime();
4070 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4071 }
4072 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4074 #if YOUNG_LIST_VERBOSE
4075 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4076 _young_list->print();
4077 #endif // YOUNG_LIST_VERBOSE
4079 if (g1_policy()->during_initial_mark_pause()) {
4080 concurrent_mark()->checkpointRootsInitialPre();
4081 }
4083 #if YOUNG_LIST_VERBOSE
4084 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4085 _young_list->print();
4086 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4087 #endif // YOUNG_LIST_VERBOSE
4089 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4091 register_humongous_regions_with_in_cset_fast_test();
4093 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4095 _cm->note_start_of_gc();
4096 // We call this after finalize_cset() to
4097 // ensure that the CSet has been finalized.
4098 _cm->verify_no_cset_oops();
4100 if (_hr_printer.is_active()) {
4101 HeapRegion* hr = g1_policy()->collection_set();
4102 while (hr != NULL) {
4103 _hr_printer.cset(hr);
4104 hr = hr->next_in_collection_set();
4105 }
4106 }
4108 #ifdef ASSERT
4109 VerifyCSetClosure cl;
4110 collection_set_iterate(&cl);
4111 #endif // ASSERT
4113 setup_surviving_young_words();
4115 // Initialize the GC alloc regions.
4116 _allocator->init_gc_alloc_regions(evacuation_info);
4118 // Actually do the work...
4119 evacuate_collection_set(evacuation_info);
4121 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4123 eagerly_reclaim_humongous_regions();
4125 g1_policy()->clear_collection_set();
4127 cleanup_surviving_young_words();
4129 // Start a new incremental collection set for the next pause.
4130 g1_policy()->start_incremental_cset_building();
4132 clear_cset_fast_test();
4134 _young_list->reset_sampled_info();
4136 // Don't check the whole heap at this point as the
4137 // GC alloc regions from this pause have been tagged
4138 // as survivors and moved on to the survivor list.
4139 // Survivor regions will fail the !is_young() check.
4140 assert(check_young_list_empty(false /* check_heap */),
4141 "young list should be empty");
4143 #if YOUNG_LIST_VERBOSE
4144 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4145 _young_list->print();
4146 #endif // YOUNG_LIST_VERBOSE
4148 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4149 _young_list->first_survivor_region(),
4150 _young_list->last_survivor_region());
4152 _young_list->reset_auxilary_lists();
4154 if (evacuation_failed()) {
4155 _allocator->set_used(recalculate_used());
4156 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4157 for (uint i = 0; i < n_queues; i++) {
4158 if (_evacuation_failed_info_array[i].has_failed()) {
4159 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4160 }
4161 }
4162 } else {
4163 // The "used" of the the collection set have already been subtracted
4164 // when they were freed. Add in the bytes evacuated.
4165 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4166 }
4168 if (g1_policy()->during_initial_mark_pause()) {
4169 // We have to do this before we notify the CM threads that
4170 // they can start working to make sure that all the
4171 // appropriate initialization is done on the CM object.
4172 concurrent_mark()->checkpointRootsInitialPost();
4173 set_marking_started();
4174 // Note that we don't actually trigger the CM thread at
4175 // this point. We do that later when we're sure that
4176 // the current thread has completed its logging output.
4177 }
4179 allocate_dummy_regions();
4181 #if YOUNG_LIST_VERBOSE
4182 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4183 _young_list->print();
4184 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4185 #endif // YOUNG_LIST_VERBOSE
4187 _allocator->init_mutator_alloc_region();
4189 {
4190 size_t expand_bytes = g1_policy()->expansion_amount();
4191 if (expand_bytes > 0) {
4192 size_t bytes_before = capacity();
4193 // No need for an ergo verbose message here,
4194 // expansion_amount() does this when it returns a value > 0.
4195 if (!expand(expand_bytes)) {
4196 // We failed to expand the heap. Cannot do anything about it.
4197 }
4198 }
4199 }
4201 // We redo the verification but now wrt to the new CSet which
4202 // has just got initialized after the previous CSet was freed.
4203 _cm->verify_no_cset_oops();
4204 _cm->note_end_of_gc();
4206 // This timing is only used by the ergonomics to handle our pause target.
4207 // It is unclear why this should not include the full pause. We will
4208 // investigate this in CR 7178365.
4209 double sample_end_time_sec = os::elapsedTime();
4210 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4211 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4213 MemoryService::track_memory_usage();
4215 // In prepare_for_verify() below we'll need to scan the deferred
4216 // update buffers to bring the RSets up-to-date if
4217 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4218 // the update buffers we'll probably need to scan cards on the
4219 // regions we just allocated to (i.e., the GC alloc
4220 // regions). However, during the last GC we called
4221 // set_saved_mark() on all the GC alloc regions, so card
4222 // scanning might skip the [saved_mark_word()...top()] area of
4223 // those regions (i.e., the area we allocated objects into
4224 // during the last GC). But it shouldn't. Given that
4225 // saved_mark_word() is conditional on whether the GC time stamp
4226 // on the region is current or not, by incrementing the GC time
4227 // stamp here we invalidate all the GC time stamps on all the
4228 // regions and saved_mark_word() will simply return top() for
4229 // all the regions. This is a nicer way of ensuring this rather
4230 // than iterating over the regions and fixing them. In fact, the
4231 // GC time stamp increment here also ensures that
4232 // saved_mark_word() will return top() between pauses, i.e.,
4233 // during concurrent refinement. So we don't need the
4234 // is_gc_active() check to decided which top to use when
4235 // scanning cards (see CR 7039627).
4236 increment_gc_time_stamp();
4238 verify_after_gc();
4239 check_bitmaps("GC End");
4241 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4242 ref_processor_stw()->verify_no_references_recorded();
4244 // CM reference discovery will be re-enabled if necessary.
4245 }
4247 // We should do this after we potentially expand the heap so
4248 // that all the COMMIT events are generated before the end GC
4249 // event, and after we retire the GC alloc regions so that all
4250 // RETIRE events are generated before the end GC event.
4251 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4253 #ifdef TRACESPINNING
4254 ParallelTaskTerminator::print_termination_counts();
4255 #endif
4257 gc_epilogue(false);
4258 }
4260 // Print the remainder of the GC log output.
4261 log_gc_footer(os::elapsedTime() - pause_start_sec);
4263 // It is not yet to safe to tell the concurrent mark to
4264 // start as we have some optional output below. We don't want the
4265 // output from the concurrent mark thread interfering with this
4266 // logging output either.
4268 _hrm.verify_optional();
4269 verify_region_sets_optional();
4271 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4272 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4274 print_heap_after_gc();
4275 trace_heap_after_gc(_gc_tracer_stw);
4277 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4278 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4279 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4280 // before any GC notifications are raised.
4281 g1mm()->update_sizes();
4283 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4284 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4285 _gc_timer_stw->register_gc_end();
4286 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4287 }
4288 // It should now be safe to tell the concurrent mark thread to start
4289 // without its logging output interfering with the logging output
4290 // that came from the pause.
4292 if (should_start_conc_mark) {
4293 // CAUTION: after the doConcurrentMark() call below,
4294 // the concurrent marking thread(s) could be running
4295 // concurrently with us. Make sure that anything after
4296 // this point does not assume that we are the only GC thread
4297 // running. Note: of course, the actual marking work will
4298 // not start until the safepoint itself is released in
4299 // SuspendibleThreadSet::desynchronize().
4300 doConcurrentMark();
4301 }
4303 return true;
4304 }
4306 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4307 _drain_in_progress = false;
4308 set_evac_failure_closure(cl);
4309 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4310 }
4312 void G1CollectedHeap::finalize_for_evac_failure() {
4313 assert(_evac_failure_scan_stack != NULL &&
4314 _evac_failure_scan_stack->length() == 0,
4315 "Postcondition");
4316 assert(!_drain_in_progress, "Postcondition");
4317 delete _evac_failure_scan_stack;
4318 _evac_failure_scan_stack = NULL;
4319 }
4321 void G1CollectedHeap::remove_self_forwarding_pointers() {
4322 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4324 double remove_self_forwards_start = os::elapsedTime();
4326 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4328 if (G1CollectedHeap::use_parallel_gc_threads()) {
4329 set_par_threads();
4330 workers()->run_task(&rsfp_task);
4331 set_par_threads(0);
4332 } else {
4333 rsfp_task.work(0);
4334 }
4336 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4338 // Reset the claim values in the regions in the collection set.
4339 reset_cset_heap_region_claim_values();
4341 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4343 // Now restore saved marks, if any.
4344 assert(_objs_with_preserved_marks.size() ==
4345 _preserved_marks_of_objs.size(), "Both or none.");
4346 while (!_objs_with_preserved_marks.is_empty()) {
4347 oop obj = _objs_with_preserved_marks.pop();
4348 markOop m = _preserved_marks_of_objs.pop();
4349 obj->set_mark(m);
4350 }
4351 _objs_with_preserved_marks.clear(true);
4352 _preserved_marks_of_objs.clear(true);
4354 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4355 }
4357 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4358 _evac_failure_scan_stack->push(obj);
4359 }
4361 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4362 assert(_evac_failure_scan_stack != NULL, "precondition");
4364 while (_evac_failure_scan_stack->length() > 0) {
4365 oop obj = _evac_failure_scan_stack->pop();
4366 _evac_failure_closure->set_region(heap_region_containing(obj));
4367 obj->oop_iterate_backwards(_evac_failure_closure);
4368 }
4369 }
4371 oop
4372 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4373 oop old) {
4374 assert(obj_in_cs(old),
4375 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4376 (HeapWord*) old));
4377 markOop m = old->mark();
4378 oop forward_ptr = old->forward_to_atomic(old);
4379 if (forward_ptr == NULL) {
4380 // Forward-to-self succeeded.
4381 assert(_par_scan_state != NULL, "par scan state");
4382 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4383 uint queue_num = _par_scan_state->queue_num();
4385 _evacuation_failed = true;
4386 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4387 if (_evac_failure_closure != cl) {
4388 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4389 assert(!_drain_in_progress,
4390 "Should only be true while someone holds the lock.");
4391 // Set the global evac-failure closure to the current thread's.
4392 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4393 set_evac_failure_closure(cl);
4394 // Now do the common part.
4395 handle_evacuation_failure_common(old, m);
4396 // Reset to NULL.
4397 set_evac_failure_closure(NULL);
4398 } else {
4399 // The lock is already held, and this is recursive.
4400 assert(_drain_in_progress, "This should only be the recursive case.");
4401 handle_evacuation_failure_common(old, m);
4402 }
4403 return old;
4404 } else {
4405 // Forward-to-self failed. Either someone else managed to allocate
4406 // space for this object (old != forward_ptr) or they beat us in
4407 // self-forwarding it (old == forward_ptr).
4408 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4409 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4410 "should not be in the CSet",
4411 (HeapWord*) old, (HeapWord*) forward_ptr));
4412 return forward_ptr;
4413 }
4414 }
4416 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4417 preserve_mark_if_necessary(old, m);
4419 HeapRegion* r = heap_region_containing(old);
4420 if (!r->evacuation_failed()) {
4421 r->set_evacuation_failed(true);
4422 _hr_printer.evac_failure(r);
4423 }
4425 push_on_evac_failure_scan_stack(old);
4427 if (!_drain_in_progress) {
4428 // prevent recursion in copy_to_survivor_space()
4429 _drain_in_progress = true;
4430 drain_evac_failure_scan_stack();
4431 _drain_in_progress = false;
4432 }
4433 }
4435 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4436 assert(evacuation_failed(), "Oversaving!");
4437 // We want to call the "for_promotion_failure" version only in the
4438 // case of a promotion failure.
4439 if (m->must_be_preserved_for_promotion_failure(obj)) {
4440 _objs_with_preserved_marks.push(obj);
4441 _preserved_marks_of_objs.push(m);
4442 }
4443 }
4445 void G1ParCopyHelper::mark_object(oop obj) {
4446 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4448 // We know that the object is not moving so it's safe to read its size.
4449 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4450 }
4452 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4453 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4454 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4455 assert(from_obj != to_obj, "should not be self-forwarded");
4457 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4458 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4460 // The object might be in the process of being copied by another
4461 // worker so we cannot trust that its to-space image is
4462 // well-formed. So we have to read its size from its from-space
4463 // image which we know should not be changing.
4464 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4465 }
4467 template <class T>
4468 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4469 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4470 _scanned_klass->record_modified_oops();
4471 }
4472 }
4474 template <G1Barrier barrier, G1Mark do_mark_object>
4475 template <class T>
4476 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4477 T heap_oop = oopDesc::load_heap_oop(p);
4479 if (oopDesc::is_null(heap_oop)) {
4480 return;
4481 }
4483 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4485 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4487 const InCSetState state = _g1->in_cset_state(obj);
4488 if (state.is_in_cset()) {
4489 oop forwardee;
4490 markOop m = obj->mark();
4491 if (m->is_marked()) {
4492 forwardee = (oop) m->decode_pointer();
4493 } else {
4494 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4495 }
4496 assert(forwardee != NULL, "forwardee should not be NULL");
4497 oopDesc::encode_store_heap_oop(p, forwardee);
4498 if (do_mark_object != G1MarkNone && forwardee != obj) {
4499 // If the object is self-forwarded we don't need to explicitly
4500 // mark it, the evacuation failure protocol will do so.
4501 mark_forwarded_object(obj, forwardee);
4502 }
4504 if (barrier == G1BarrierKlass) {
4505 do_klass_barrier(p, forwardee);
4506 }
4507 } else {
4508 if (state.is_humongous()) {
4509 _g1->set_humongous_is_live(obj);
4510 }
4511 // The object is not in collection set. If we're a root scanning
4512 // closure during an initial mark pause then attempt to mark the object.
4513 if (do_mark_object == G1MarkFromRoot) {
4514 mark_object(obj);
4515 }
4516 }
4518 if (barrier == G1BarrierEvac) {
4519 _par_scan_state->update_rs(_from, p, _worker_id);
4520 }
4521 }
4523 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4524 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4526 class G1ParEvacuateFollowersClosure : public VoidClosure {
4527 protected:
4528 G1CollectedHeap* _g1h;
4529 G1ParScanThreadState* _par_scan_state;
4530 RefToScanQueueSet* _queues;
4531 ParallelTaskTerminator* _terminator;
4533 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4534 RefToScanQueueSet* queues() { return _queues; }
4535 ParallelTaskTerminator* terminator() { return _terminator; }
4537 public:
4538 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4539 G1ParScanThreadState* par_scan_state,
4540 RefToScanQueueSet* queues,
4541 ParallelTaskTerminator* terminator)
4542 : _g1h(g1h), _par_scan_state(par_scan_state),
4543 _queues(queues), _terminator(terminator) {}
4545 void do_void();
4547 private:
4548 inline bool offer_termination();
4549 };
4551 bool G1ParEvacuateFollowersClosure::offer_termination() {
4552 G1ParScanThreadState* const pss = par_scan_state();
4553 pss->start_term_time();
4554 const bool res = terminator()->offer_termination();
4555 pss->end_term_time();
4556 return res;
4557 }
4559 void G1ParEvacuateFollowersClosure::do_void() {
4560 G1ParScanThreadState* const pss = par_scan_state();
4561 pss->trim_queue();
4562 do {
4563 pss->steal_and_trim_queue(queues());
4564 } while (!offer_termination());
4565 }
4567 class G1KlassScanClosure : public KlassClosure {
4568 G1ParCopyHelper* _closure;
4569 bool _process_only_dirty;
4570 int _count;
4571 public:
4572 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4573 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4574 void do_klass(Klass* klass) {
4575 // If the klass has not been dirtied we know that there's
4576 // no references into the young gen and we can skip it.
4577 if (!_process_only_dirty || klass->has_modified_oops()) {
4578 // Clean the klass since we're going to scavenge all the metadata.
4579 klass->clear_modified_oops();
4581 // Tell the closure that this klass is the Klass to scavenge
4582 // and is the one to dirty if oops are left pointing into the young gen.
4583 _closure->set_scanned_klass(klass);
4585 klass->oops_do(_closure);
4587 _closure->set_scanned_klass(NULL);
4588 }
4589 _count++;
4590 }
4591 };
4593 class G1ParTask : public AbstractGangTask {
4594 protected:
4595 G1CollectedHeap* _g1h;
4596 RefToScanQueueSet *_queues;
4597 G1RootProcessor* _root_processor;
4598 ParallelTaskTerminator _terminator;
4599 uint _n_workers;
4601 Mutex _stats_lock;
4602 Mutex* stats_lock() { return &_stats_lock; }
4604 public:
4605 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4606 : AbstractGangTask("G1 collection"),
4607 _g1h(g1h),
4608 _queues(task_queues),
4609 _root_processor(root_processor),
4610 _terminator(0, _queues),
4611 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4612 {}
4614 RefToScanQueueSet* queues() { return _queues; }
4616 RefToScanQueue *work_queue(int i) {
4617 return queues()->queue(i);
4618 }
4620 ParallelTaskTerminator* terminator() { return &_terminator; }
4622 virtual void set_for_termination(int active_workers) {
4623 _root_processor->set_num_workers(active_workers);
4624 terminator()->reset_for_reuse(active_workers);
4625 _n_workers = active_workers;
4626 }
4628 // Helps out with CLD processing.
4629 //
4630 // During InitialMark we need to:
4631 // 1) Scavenge all CLDs for the young GC.
4632 // 2) Mark all objects directly reachable from strong CLDs.
4633 template <G1Mark do_mark_object>
4634 class G1CLDClosure : public CLDClosure {
4635 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4636 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4637 G1KlassScanClosure _klass_in_cld_closure;
4638 bool _claim;
4640 public:
4641 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4642 bool only_young, bool claim)
4643 : _oop_closure(oop_closure),
4644 _oop_in_klass_closure(oop_closure->g1(),
4645 oop_closure->pss(),
4646 oop_closure->rp()),
4647 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4648 _claim(claim) {
4650 }
4652 void do_cld(ClassLoaderData* cld) {
4653 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4654 }
4655 };
4657 void work(uint worker_id) {
4658 if (worker_id >= _n_workers) return; // no work needed this round
4660 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4662 {
4663 ResourceMark rm;
4664 HandleMark hm;
4666 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4668 G1ParScanThreadState pss(_g1h, worker_id, rp);
4669 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4671 pss.set_evac_failure_closure(&evac_failure_cl);
4673 bool only_young = _g1h->g1_policy()->gcs_are_young();
4675 // Non-IM young GC.
4676 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4677 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4678 only_young, // Only process dirty klasses.
4679 false); // No need to claim CLDs.
4680 // IM young GC.
4681 // Strong roots closures.
4682 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4683 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4684 false, // Process all klasses.
4685 true); // Need to claim CLDs.
4686 // Weak roots closures.
4687 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4688 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4689 false, // Process all klasses.
4690 true); // Need to claim CLDs.
4692 OopClosure* strong_root_cl;
4693 OopClosure* weak_root_cl;
4694 CLDClosure* strong_cld_cl;
4695 CLDClosure* weak_cld_cl;
4697 bool trace_metadata = false;
4699 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4700 // We also need to mark copied objects.
4701 strong_root_cl = &scan_mark_root_cl;
4702 strong_cld_cl = &scan_mark_cld_cl;
4703 if (ClassUnloadingWithConcurrentMark) {
4704 weak_root_cl = &scan_mark_weak_root_cl;
4705 weak_cld_cl = &scan_mark_weak_cld_cl;
4706 trace_metadata = true;
4707 } else {
4708 weak_root_cl = &scan_mark_root_cl;
4709 weak_cld_cl = &scan_mark_cld_cl;
4710 }
4711 } else {
4712 strong_root_cl = &scan_only_root_cl;
4713 weak_root_cl = &scan_only_root_cl;
4714 strong_cld_cl = &scan_only_cld_cl;
4715 weak_cld_cl = &scan_only_cld_cl;
4716 }
4718 pss.start_strong_roots();
4720 _root_processor->evacuate_roots(strong_root_cl,
4721 weak_root_cl,
4722 strong_cld_cl,
4723 weak_cld_cl,
4724 trace_metadata,
4725 worker_id);
4727 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4728 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4729 weak_root_cl,
4730 worker_id);
4731 pss.end_strong_roots();
4733 {
4734 double start = os::elapsedTime();
4735 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4736 evac.do_void();
4737 double elapsed_sec = os::elapsedTime() - start;
4738 double term_sec = pss.term_time();
4739 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4740 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4741 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4742 }
4743 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4744 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4746 if (ParallelGCVerbose) {
4747 MutexLocker x(stats_lock());
4748 pss.print_termination_stats(worker_id);
4749 }
4751 assert(pss.queue_is_empty(), "should be empty");
4753 // Close the inner scope so that the ResourceMark and HandleMark
4754 // destructors are executed here and are included as part of the
4755 // "GC Worker Time".
4756 }
4757 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4758 }
4759 };
4761 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4762 private:
4763 BoolObjectClosure* _is_alive;
4764 int _initial_string_table_size;
4765 int _initial_symbol_table_size;
4767 bool _process_strings;
4768 int _strings_processed;
4769 int _strings_removed;
4771 bool _process_symbols;
4772 int _symbols_processed;
4773 int _symbols_removed;
4775 bool _do_in_parallel;
4776 public:
4777 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4778 AbstractGangTask("String/Symbol Unlinking"),
4779 _is_alive(is_alive),
4780 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4781 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4782 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4784 _initial_string_table_size = StringTable::the_table()->table_size();
4785 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4786 if (process_strings) {
4787 StringTable::clear_parallel_claimed_index();
4788 }
4789 if (process_symbols) {
4790 SymbolTable::clear_parallel_claimed_index();
4791 }
4792 }
4794 ~G1StringSymbolTableUnlinkTask() {
4795 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4796 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4797 StringTable::parallel_claimed_index(), _initial_string_table_size));
4798 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4799 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4800 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4802 if (G1TraceStringSymbolTableScrubbing) {
4803 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4804 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4805 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4806 strings_processed(), strings_removed(),
4807 symbols_processed(), symbols_removed());
4808 }
4809 }
4811 void work(uint worker_id) {
4812 if (_do_in_parallel) {
4813 int strings_processed = 0;
4814 int strings_removed = 0;
4815 int symbols_processed = 0;
4816 int symbols_removed = 0;
4817 if (_process_strings) {
4818 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4819 Atomic::add(strings_processed, &_strings_processed);
4820 Atomic::add(strings_removed, &_strings_removed);
4821 }
4822 if (_process_symbols) {
4823 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4824 Atomic::add(symbols_processed, &_symbols_processed);
4825 Atomic::add(symbols_removed, &_symbols_removed);
4826 }
4827 } else {
4828 if (_process_strings) {
4829 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
4830 }
4831 if (_process_symbols) {
4832 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
4833 }
4834 }
4835 }
4837 size_t strings_processed() const { return (size_t)_strings_processed; }
4838 size_t strings_removed() const { return (size_t)_strings_removed; }
4840 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4841 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4842 };
4844 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4845 private:
4846 static Monitor* _lock;
4848 BoolObjectClosure* const _is_alive;
4849 const bool _unloading_occurred;
4850 const uint _num_workers;
4852 // Variables used to claim nmethods.
4853 nmethod* _first_nmethod;
4854 volatile nmethod* _claimed_nmethod;
4856 // The list of nmethods that need to be processed by the second pass.
4857 volatile nmethod* _postponed_list;
4858 volatile uint _num_entered_barrier;
4860 public:
4861 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4862 _is_alive(is_alive),
4863 _unloading_occurred(unloading_occurred),
4864 _num_workers(num_workers),
4865 _first_nmethod(NULL),
4866 _claimed_nmethod(NULL),
4867 _postponed_list(NULL),
4868 _num_entered_barrier(0)
4869 {
4870 nmethod::increase_unloading_clock();
4871 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
4872 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4873 }
4875 ~G1CodeCacheUnloadingTask() {
4876 CodeCache::verify_clean_inline_caches();
4878 CodeCache::set_needs_cache_clean(false);
4879 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4881 CodeCache::verify_icholder_relocations();
4882 }
4884 private:
4885 void add_to_postponed_list(nmethod* nm) {
4886 nmethod* old;
4887 do {
4888 old = (nmethod*)_postponed_list;
4889 nm->set_unloading_next(old);
4890 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4891 }
4893 void clean_nmethod(nmethod* nm) {
4894 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4896 if (postponed) {
4897 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4898 add_to_postponed_list(nm);
4899 }
4901 // Mark that this thread has been cleaned/unloaded.
4902 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4903 nm->set_unloading_clock(nmethod::global_unloading_clock());
4904 }
4906 void clean_nmethod_postponed(nmethod* nm) {
4907 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4908 }
4910 static const int MaxClaimNmethods = 16;
4912 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4913 nmethod* first;
4914 nmethod* last;
4916 do {
4917 *num_claimed_nmethods = 0;
4919 first = last = (nmethod*)_claimed_nmethod;
4921 if (first != NULL) {
4922 for (int i = 0; i < MaxClaimNmethods; i++) {
4923 last = CodeCache::alive_nmethod(CodeCache::next(last));
4925 if (last == NULL) {
4926 break;
4927 }
4929 claimed_nmethods[i] = last;
4930 (*num_claimed_nmethods)++;
4931 }
4932 }
4934 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
4935 }
4937 nmethod* claim_postponed_nmethod() {
4938 nmethod* claim;
4939 nmethod* next;
4941 do {
4942 claim = (nmethod*)_postponed_list;
4943 if (claim == NULL) {
4944 return NULL;
4945 }
4947 next = claim->unloading_next();
4949 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4951 return claim;
4952 }
4954 public:
4955 // Mark that we're done with the first pass of nmethod cleaning.
4956 void barrier_mark(uint worker_id) {
4957 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4958 _num_entered_barrier++;
4959 if (_num_entered_barrier == _num_workers) {
4960 ml.notify_all();
4961 }
4962 }
4964 // See if we have to wait for the other workers to
4965 // finish their first-pass nmethod cleaning work.
4966 void barrier_wait(uint worker_id) {
4967 if (_num_entered_barrier < _num_workers) {
4968 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4969 while (_num_entered_barrier < _num_workers) {
4970 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4971 }
4972 }
4973 }
4975 // Cleaning and unloading of nmethods. Some work has to be postponed
4976 // to the second pass, when we know which nmethods survive.
4977 void work_first_pass(uint worker_id) {
4978 // The first nmethods is claimed by the first worker.
4979 if (worker_id == 0 && _first_nmethod != NULL) {
4980 clean_nmethod(_first_nmethod);
4981 _first_nmethod = NULL;
4982 }
4984 int num_claimed_nmethods;
4985 nmethod* claimed_nmethods[MaxClaimNmethods];
4987 while (true) {
4988 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4990 if (num_claimed_nmethods == 0) {
4991 break;
4992 }
4994 for (int i = 0; i < num_claimed_nmethods; i++) {
4995 clean_nmethod(claimed_nmethods[i]);
4996 }
4997 }
4999 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
5000 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
5001 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
5002 }
5004 void work_second_pass(uint worker_id) {
5005 nmethod* nm;
5006 // Take care of postponed nmethods.
5007 while ((nm = claim_postponed_nmethod()) != NULL) {
5008 clean_nmethod_postponed(nm);
5009 }
5010 }
5011 };
5013 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5015 class G1KlassCleaningTask : public StackObj {
5016 BoolObjectClosure* _is_alive;
5017 volatile jint _clean_klass_tree_claimed;
5018 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5020 public:
5021 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5022 _is_alive(is_alive),
5023 _clean_klass_tree_claimed(0),
5024 _klass_iterator() {
5025 }
5027 private:
5028 bool claim_clean_klass_tree_task() {
5029 if (_clean_klass_tree_claimed) {
5030 return false;
5031 }
5033 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5034 }
5036 InstanceKlass* claim_next_klass() {
5037 Klass* klass;
5038 do {
5039 klass =_klass_iterator.next_klass();
5040 } while (klass != NULL && !klass->oop_is_instance());
5042 return (InstanceKlass*)klass;
5043 }
5045 public:
5047 void clean_klass(InstanceKlass* ik) {
5048 ik->clean_implementors_list(_is_alive);
5049 ik->clean_method_data(_is_alive);
5051 // G1 specific cleanup work that has
5052 // been moved here to be done in parallel.
5053 ik->clean_dependent_nmethods();
5054 if (JvmtiExport::has_redefined_a_class()) {
5055 InstanceKlass::purge_previous_versions(ik);
5056 }
5057 }
5059 void work() {
5060 ResourceMark rm;
5062 // One worker will clean the subklass/sibling klass tree.
5063 if (claim_clean_klass_tree_task()) {
5064 Klass::clean_subklass_tree(_is_alive);
5065 }
5067 // All workers will help cleaning the classes,
5068 InstanceKlass* klass;
5069 while ((klass = claim_next_klass()) != NULL) {
5070 clean_klass(klass);
5071 }
5072 }
5073 };
5075 // To minimize the remark pause times, the tasks below are done in parallel.
5076 class G1ParallelCleaningTask : public AbstractGangTask {
5077 private:
5078 G1StringSymbolTableUnlinkTask _string_symbol_task;
5079 G1CodeCacheUnloadingTask _code_cache_task;
5080 G1KlassCleaningTask _klass_cleaning_task;
5082 public:
5083 // The constructor is run in the VMThread.
5084 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5085 AbstractGangTask("Parallel Cleaning"),
5086 _string_symbol_task(is_alive, process_strings, process_symbols),
5087 _code_cache_task(num_workers, is_alive, unloading_occurred),
5088 _klass_cleaning_task(is_alive) {
5089 }
5091 void pre_work_verification() {
5092 // The VM Thread will have registered Metadata during the single-threaded phase of MetadataStackOnMark.
5093 assert(Thread::current()->is_VM_thread()
5094 || !MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5095 }
5097 void post_work_verification() {
5098 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5099 }
5101 // The parallel work done by all worker threads.
5102 void work(uint worker_id) {
5103 pre_work_verification();
5105 // Do first pass of code cache cleaning.
5106 _code_cache_task.work_first_pass(worker_id);
5108 // Let the threads mark that the first pass is done.
5109 _code_cache_task.barrier_mark(worker_id);
5111 // Clean the Strings and Symbols.
5112 _string_symbol_task.work(worker_id);
5114 // Wait for all workers to finish the first code cache cleaning pass.
5115 _code_cache_task.barrier_wait(worker_id);
5117 // Do the second code cache cleaning work, which realize on
5118 // the liveness information gathered during the first pass.
5119 _code_cache_task.work_second_pass(worker_id);
5121 // Clean all klasses that were not unloaded.
5122 _klass_cleaning_task.work();
5124 post_work_verification();
5125 }
5126 };
5129 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5130 bool process_strings,
5131 bool process_symbols,
5132 bool class_unloading_occurred) {
5133 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5134 workers()->active_workers() : 1);
5136 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5137 n_workers, class_unloading_occurred);
5138 if (G1CollectedHeap::use_parallel_gc_threads()) {
5139 set_par_threads(n_workers);
5140 workers()->run_task(&g1_unlink_task);
5141 set_par_threads(0);
5142 } else {
5143 g1_unlink_task.work(0);
5144 }
5145 }
5147 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5148 bool process_strings, bool process_symbols) {
5149 {
5150 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5151 _g1h->workers()->active_workers() : 1);
5152 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5153 if (G1CollectedHeap::use_parallel_gc_threads()) {
5154 set_par_threads(n_workers);
5155 workers()->run_task(&g1_unlink_task);
5156 set_par_threads(0);
5157 } else {
5158 g1_unlink_task.work(0);
5159 }
5160 }
5162 if (G1StringDedup::is_enabled()) {
5163 G1StringDedup::unlink(is_alive);
5164 }
5165 }
5167 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5168 private:
5169 DirtyCardQueueSet* _queue;
5170 public:
5171 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5173 virtual void work(uint worker_id) {
5174 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5175 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5177 RedirtyLoggedCardTableEntryClosure cl;
5178 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5179 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5180 } else {
5181 _queue->apply_closure_to_all_completed_buffers(&cl);
5182 }
5184 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5185 }
5186 };
5188 void G1CollectedHeap::redirty_logged_cards() {
5189 double redirty_logged_cards_start = os::elapsedTime();
5191 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5192 _g1h->workers()->active_workers() : 1);
5194 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5195 dirty_card_queue_set().reset_for_par_iteration();
5196 if (use_parallel_gc_threads()) {
5197 set_par_threads(n_workers);
5198 workers()->run_task(&redirty_task);
5199 set_par_threads(0);
5200 } else {
5201 redirty_task.work(0);
5202 }
5204 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5205 dcq.merge_bufferlists(&dirty_card_queue_set());
5206 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5208 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5209 }
5211 // Weak Reference Processing support
5213 // An always "is_alive" closure that is used to preserve referents.
5214 // If the object is non-null then it's alive. Used in the preservation
5215 // of referent objects that are pointed to by reference objects
5216 // discovered by the CM ref processor.
5217 class G1AlwaysAliveClosure: public BoolObjectClosure {
5218 G1CollectedHeap* _g1;
5219 public:
5220 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5221 bool do_object_b(oop p) {
5222 if (p != NULL) {
5223 return true;
5224 }
5225 return false;
5226 }
5227 };
5229 bool G1STWIsAliveClosure::do_object_b(oop p) {
5230 // An object is reachable if it is outside the collection set,
5231 // or is inside and copied.
5232 return !_g1->obj_in_cs(p) || p->is_forwarded();
5233 }
5235 // Non Copying Keep Alive closure
5236 class G1KeepAliveClosure: public OopClosure {
5237 G1CollectedHeap* _g1;
5238 public:
5239 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5240 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5241 void do_oop(oop* p) {
5242 oop obj = *p;
5243 assert(obj != NULL, "the caller should have filtered out NULL values");
5245 const InCSetState cset_state = _g1->in_cset_state(obj);
5246 if (!cset_state.is_in_cset_or_humongous()) {
5247 return;
5248 }
5249 if (cset_state.is_in_cset()) {
5250 assert( obj->is_forwarded(), "invariant" );
5251 *p = obj->forwardee();
5252 } else {
5253 assert(!obj->is_forwarded(), "invariant" );
5254 assert(cset_state.is_humongous(),
5255 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5256 _g1->set_humongous_is_live(obj);
5257 }
5258 }
5259 };
5261 // Copying Keep Alive closure - can be called from both
5262 // serial and parallel code as long as different worker
5263 // threads utilize different G1ParScanThreadState instances
5264 // and different queues.
5266 class G1CopyingKeepAliveClosure: public OopClosure {
5267 G1CollectedHeap* _g1h;
5268 OopClosure* _copy_non_heap_obj_cl;
5269 G1ParScanThreadState* _par_scan_state;
5271 public:
5272 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5273 OopClosure* non_heap_obj_cl,
5274 G1ParScanThreadState* pss):
5275 _g1h(g1h),
5276 _copy_non_heap_obj_cl(non_heap_obj_cl),
5277 _par_scan_state(pss)
5278 {}
5280 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5281 virtual void do_oop( oop* p) { do_oop_work(p); }
5283 template <class T> void do_oop_work(T* p) {
5284 oop obj = oopDesc::load_decode_heap_oop(p);
5286 if (_g1h->is_in_cset_or_humongous(obj)) {
5287 // If the referent object has been forwarded (either copied
5288 // to a new location or to itself in the event of an
5289 // evacuation failure) then we need to update the reference
5290 // field and, if both reference and referent are in the G1
5291 // heap, update the RSet for the referent.
5292 //
5293 // If the referent has not been forwarded then we have to keep
5294 // it alive by policy. Therefore we have copy the referent.
5295 //
5296 // If the reference field is in the G1 heap then we can push
5297 // on the PSS queue. When the queue is drained (after each
5298 // phase of reference processing) the object and it's followers
5299 // will be copied, the reference field set to point to the
5300 // new location, and the RSet updated. Otherwise we need to
5301 // use the the non-heap or metadata closures directly to copy
5302 // the referent object and update the pointer, while avoiding
5303 // updating the RSet.
5305 if (_g1h->is_in_g1_reserved(p)) {
5306 _par_scan_state->push_on_queue(p);
5307 } else {
5308 assert(!Metaspace::contains((const void*)p),
5309 err_msg("Unexpectedly found a pointer from metadata: "
5310 PTR_FORMAT, p));
5311 _copy_non_heap_obj_cl->do_oop(p);
5312 }
5313 }
5314 }
5315 };
5317 // Serial drain queue closure. Called as the 'complete_gc'
5318 // closure for each discovered list in some of the
5319 // reference processing phases.
5321 class G1STWDrainQueueClosure: public VoidClosure {
5322 protected:
5323 G1CollectedHeap* _g1h;
5324 G1ParScanThreadState* _par_scan_state;
5326 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5328 public:
5329 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5330 _g1h(g1h),
5331 _par_scan_state(pss)
5332 { }
5334 void do_void() {
5335 G1ParScanThreadState* const pss = par_scan_state();
5336 pss->trim_queue();
5337 }
5338 };
5340 // Parallel Reference Processing closures
5342 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5343 // processing during G1 evacuation pauses.
5345 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5346 private:
5347 G1CollectedHeap* _g1h;
5348 RefToScanQueueSet* _queues;
5349 FlexibleWorkGang* _workers;
5350 int _active_workers;
5352 public:
5353 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5354 FlexibleWorkGang* workers,
5355 RefToScanQueueSet *task_queues,
5356 int n_workers) :
5357 _g1h(g1h),
5358 _queues(task_queues),
5359 _workers(workers),
5360 _active_workers(n_workers)
5361 {
5362 assert(n_workers > 0, "shouldn't call this otherwise");
5363 }
5365 // Executes the given task using concurrent marking worker threads.
5366 virtual void execute(ProcessTask& task);
5367 virtual void execute(EnqueueTask& task);
5368 };
5370 // Gang task for possibly parallel reference processing
5372 class G1STWRefProcTaskProxy: public AbstractGangTask {
5373 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5374 ProcessTask& _proc_task;
5375 G1CollectedHeap* _g1h;
5376 RefToScanQueueSet *_task_queues;
5377 ParallelTaskTerminator* _terminator;
5379 public:
5380 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5381 G1CollectedHeap* g1h,
5382 RefToScanQueueSet *task_queues,
5383 ParallelTaskTerminator* terminator) :
5384 AbstractGangTask("Process reference objects in parallel"),
5385 _proc_task(proc_task),
5386 _g1h(g1h),
5387 _task_queues(task_queues),
5388 _terminator(terminator)
5389 {}
5391 virtual void work(uint worker_id) {
5392 // The reference processing task executed by a single worker.
5393 ResourceMark rm;
5394 HandleMark hm;
5396 G1STWIsAliveClosure is_alive(_g1h);
5398 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5399 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5401 pss.set_evac_failure_closure(&evac_failure_cl);
5403 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5405 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5407 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5409 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5410 // We also need to mark copied objects.
5411 copy_non_heap_cl = ©_mark_non_heap_cl;
5412 }
5414 // Keep alive closure.
5415 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5417 // Complete GC closure
5418 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5420 // Call the reference processing task's work routine.
5421 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5423 // Note we cannot assert that the refs array is empty here as not all
5424 // of the processing tasks (specifically phase2 - pp2_work) execute
5425 // the complete_gc closure (which ordinarily would drain the queue) so
5426 // the queue may not be empty.
5427 }
5428 };
5430 // Driver routine for parallel reference processing.
5431 // Creates an instance of the ref processing gang
5432 // task and has the worker threads execute it.
5433 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5434 assert(_workers != NULL, "Need parallel worker threads.");
5436 ParallelTaskTerminator terminator(_active_workers, _queues);
5437 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5439 _g1h->set_par_threads(_active_workers);
5440 _workers->run_task(&proc_task_proxy);
5441 _g1h->set_par_threads(0);
5442 }
5444 // Gang task for parallel reference enqueueing.
5446 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5447 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5448 EnqueueTask& _enq_task;
5450 public:
5451 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5452 AbstractGangTask("Enqueue reference objects in parallel"),
5453 _enq_task(enq_task)
5454 { }
5456 virtual void work(uint worker_id) {
5457 _enq_task.work(worker_id);
5458 }
5459 };
5461 // Driver routine for parallel reference enqueueing.
5462 // Creates an instance of the ref enqueueing gang
5463 // task and has the worker threads execute it.
5465 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5466 assert(_workers != NULL, "Need parallel worker threads.");
5468 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5470 _g1h->set_par_threads(_active_workers);
5471 _workers->run_task(&enq_task_proxy);
5472 _g1h->set_par_threads(0);
5473 }
5475 // End of weak reference support closures
5477 // Abstract task used to preserve (i.e. copy) any referent objects
5478 // that are in the collection set and are pointed to by reference
5479 // objects discovered by the CM ref processor.
5481 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5482 protected:
5483 G1CollectedHeap* _g1h;
5484 RefToScanQueueSet *_queues;
5485 ParallelTaskTerminator _terminator;
5486 uint _n_workers;
5488 public:
5489 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5490 AbstractGangTask("ParPreserveCMReferents"),
5491 _g1h(g1h),
5492 _queues(task_queues),
5493 _terminator(workers, _queues),
5494 _n_workers(workers)
5495 { }
5497 void work(uint worker_id) {
5498 ResourceMark rm;
5499 HandleMark hm;
5501 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5502 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5504 pss.set_evac_failure_closure(&evac_failure_cl);
5506 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5508 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5510 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5512 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5514 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5515 // We also need to mark copied objects.
5516 copy_non_heap_cl = ©_mark_non_heap_cl;
5517 }
5519 // Is alive closure
5520 G1AlwaysAliveClosure always_alive(_g1h);
5522 // Copying keep alive closure. Applied to referent objects that need
5523 // to be copied.
5524 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5526 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5528 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5529 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5531 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5532 // So this must be true - but assert just in case someone decides to
5533 // change the worker ids.
5534 assert(0 <= worker_id && worker_id < limit, "sanity");
5535 assert(!rp->discovery_is_atomic(), "check this code");
5537 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5538 for (uint idx = worker_id; idx < limit; idx += stride) {
5539 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5541 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5542 while (iter.has_next()) {
5543 // Since discovery is not atomic for the CM ref processor, we
5544 // can see some null referent objects.
5545 iter.load_ptrs(DEBUG_ONLY(true));
5546 oop ref = iter.obj();
5548 // This will filter nulls.
5549 if (iter.is_referent_alive()) {
5550 iter.make_referent_alive();
5551 }
5552 iter.move_to_next();
5553 }
5554 }
5556 // Drain the queue - which may cause stealing
5557 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5558 drain_queue.do_void();
5559 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5560 assert(pss.queue_is_empty(), "should be");
5561 }
5562 };
5564 // Weak Reference processing during an evacuation pause (part 1).
5565 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5566 double ref_proc_start = os::elapsedTime();
5568 ReferenceProcessor* rp = _ref_processor_stw;
5569 assert(rp->discovery_enabled(), "should have been enabled");
5571 // Any reference objects, in the collection set, that were 'discovered'
5572 // by the CM ref processor should have already been copied (either by
5573 // applying the external root copy closure to the discovered lists, or
5574 // by following an RSet entry).
5575 //
5576 // But some of the referents, that are in the collection set, that these
5577 // reference objects point to may not have been copied: the STW ref
5578 // processor would have seen that the reference object had already
5579 // been 'discovered' and would have skipped discovering the reference,
5580 // but would not have treated the reference object as a regular oop.
5581 // As a result the copy closure would not have been applied to the
5582 // referent object.
5583 //
5584 // We need to explicitly copy these referent objects - the references
5585 // will be processed at the end of remarking.
5586 //
5587 // We also need to do this copying before we process the reference
5588 // objects discovered by the STW ref processor in case one of these
5589 // referents points to another object which is also referenced by an
5590 // object discovered by the STW ref processor.
5592 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5593 no_of_gc_workers == workers()->active_workers(),
5594 "Need to reset active GC workers");
5596 set_par_threads(no_of_gc_workers);
5597 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5598 no_of_gc_workers,
5599 _task_queues);
5601 if (G1CollectedHeap::use_parallel_gc_threads()) {
5602 workers()->run_task(&keep_cm_referents);
5603 } else {
5604 keep_cm_referents.work(0);
5605 }
5607 set_par_threads(0);
5609 // Closure to test whether a referent is alive.
5610 G1STWIsAliveClosure is_alive(this);
5612 // Even when parallel reference processing is enabled, the processing
5613 // of JNI refs is serial and performed serially by the current thread
5614 // rather than by a worker. The following PSS will be used for processing
5615 // JNI refs.
5617 // Use only a single queue for this PSS.
5618 G1ParScanThreadState pss(this, 0, NULL);
5620 // We do not embed a reference processor in the copying/scanning
5621 // closures while we're actually processing the discovered
5622 // reference objects.
5623 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5625 pss.set_evac_failure_closure(&evac_failure_cl);
5627 assert(pss.queue_is_empty(), "pre-condition");
5629 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5631 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5633 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5635 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5636 // We also need to mark copied objects.
5637 copy_non_heap_cl = ©_mark_non_heap_cl;
5638 }
5640 // Keep alive closure.
5641 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5643 // Serial Complete GC closure
5644 G1STWDrainQueueClosure drain_queue(this, &pss);
5646 // Setup the soft refs policy...
5647 rp->setup_policy(false);
5649 ReferenceProcessorStats stats;
5650 if (!rp->processing_is_mt()) {
5651 // Serial reference processing...
5652 stats = rp->process_discovered_references(&is_alive,
5653 &keep_alive,
5654 &drain_queue,
5655 NULL,
5656 _gc_timer_stw,
5657 _gc_tracer_stw->gc_id());
5658 } else {
5659 // Parallel reference processing
5660 assert(rp->num_q() == no_of_gc_workers, "sanity");
5661 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5663 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5664 stats = rp->process_discovered_references(&is_alive,
5665 &keep_alive,
5666 &drain_queue,
5667 &par_task_executor,
5668 _gc_timer_stw,
5669 _gc_tracer_stw->gc_id());
5670 }
5672 _gc_tracer_stw->report_gc_reference_stats(stats);
5674 // We have completed copying any necessary live referent objects.
5675 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5677 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5678 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5679 }
5681 // Weak Reference processing during an evacuation pause (part 2).
5682 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5683 double ref_enq_start = os::elapsedTime();
5685 ReferenceProcessor* rp = _ref_processor_stw;
5686 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5688 // Now enqueue any remaining on the discovered lists on to
5689 // the pending list.
5690 if (!rp->processing_is_mt()) {
5691 // Serial reference processing...
5692 rp->enqueue_discovered_references();
5693 } else {
5694 // Parallel reference enqueueing
5696 assert(no_of_gc_workers == workers()->active_workers(),
5697 "Need to reset active workers");
5698 assert(rp->num_q() == no_of_gc_workers, "sanity");
5699 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5701 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5702 rp->enqueue_discovered_references(&par_task_executor);
5703 }
5705 rp->verify_no_references_recorded();
5706 assert(!rp->discovery_enabled(), "should have been disabled");
5708 // FIXME
5709 // CM's reference processing also cleans up the string and symbol tables.
5710 // Should we do that here also? We could, but it is a serial operation
5711 // and could significantly increase the pause time.
5713 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5714 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5715 }
5717 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5718 _expand_heap_after_alloc_failure = true;
5719 _evacuation_failed = false;
5721 // Should G1EvacuationFailureALot be in effect for this GC?
5722 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5724 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5726 // Disable the hot card cache.
5727 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5728 hot_card_cache->reset_hot_cache_claimed_index();
5729 hot_card_cache->set_use_cache(false);
5731 uint n_workers;
5732 if (G1CollectedHeap::use_parallel_gc_threads()) {
5733 n_workers =
5734 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5735 workers()->active_workers(),
5736 Threads::number_of_non_daemon_threads());
5737 assert(UseDynamicNumberOfGCThreads ||
5738 n_workers == workers()->total_workers(),
5739 "If not dynamic should be using all the workers");
5740 workers()->set_active_workers(n_workers);
5741 set_par_threads(n_workers);
5742 } else {
5743 assert(n_par_threads() == 0,
5744 "Should be the original non-parallel value");
5745 n_workers = 1;
5746 }
5749 init_for_evac_failure(NULL);
5751 rem_set()->prepare_for_younger_refs_iterate(true);
5753 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5754 double start_par_time_sec = os::elapsedTime();
5755 double end_par_time_sec;
5757 {
5758 G1RootProcessor root_processor(this);
5759 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5760 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5761 if (g1_policy()->during_initial_mark_pause()) {
5762 ClassLoaderDataGraph::clear_claimed_marks();
5763 }
5765 if (G1CollectedHeap::use_parallel_gc_threads()) {
5766 // The individual threads will set their evac-failure closures.
5767 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5768 // These tasks use ShareHeap::_process_strong_tasks
5769 assert(UseDynamicNumberOfGCThreads ||
5770 workers()->active_workers() == workers()->total_workers(),
5771 "If not dynamic should be using all the workers");
5772 workers()->run_task(&g1_par_task);
5773 } else {
5774 g1_par_task.set_for_termination(n_workers);
5775 g1_par_task.work(0);
5776 }
5777 end_par_time_sec = os::elapsedTime();
5779 // Closing the inner scope will execute the destructor
5780 // for the G1RootProcessor object. We record the current
5781 // elapsed time before closing the scope so that time
5782 // taken for the destructor is NOT included in the
5783 // reported parallel time.
5784 }
5786 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5788 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5789 phase_times->record_par_time(par_time_ms);
5791 double code_root_fixup_time_ms =
5792 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5793 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5795 set_par_threads(0);
5797 // Process any discovered reference objects - we have
5798 // to do this _before_ we retire the GC alloc regions
5799 // as we may have to copy some 'reachable' referent
5800 // objects (and their reachable sub-graphs) that were
5801 // not copied during the pause.
5802 process_discovered_references(n_workers);
5804 if (G1StringDedup::is_enabled()) {
5805 double fixup_start = os::elapsedTime();
5807 G1STWIsAliveClosure is_alive(this);
5808 G1KeepAliveClosure keep_alive(this);
5809 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5811 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5812 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5813 }
5815 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5816 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5818 // Reset and re-enable the hot card cache.
5819 // Note the counts for the cards in the regions in the
5820 // collection set are reset when the collection set is freed.
5821 hot_card_cache->reset_hot_cache();
5822 hot_card_cache->set_use_cache(true);
5824 purge_code_root_memory();
5826 if (g1_policy()->during_initial_mark_pause()) {
5827 // Reset the claim values set during marking the strong code roots
5828 reset_heap_region_claim_values();
5829 }
5831 finalize_for_evac_failure();
5833 if (evacuation_failed()) {
5834 remove_self_forwarding_pointers();
5836 // Reset the G1EvacuationFailureALot counters and flags
5837 // Note: the values are reset only when an actual
5838 // evacuation failure occurs.
5839 NOT_PRODUCT(reset_evacuation_should_fail();)
5840 }
5842 // Enqueue any remaining references remaining on the STW
5843 // reference processor's discovered lists. We need to do
5844 // this after the card table is cleaned (and verified) as
5845 // the act of enqueueing entries on to the pending list
5846 // will log these updates (and dirty their associated
5847 // cards). We need these updates logged to update any
5848 // RSets.
5849 enqueue_discovered_references(n_workers);
5851 redirty_logged_cards();
5852 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5853 }
5855 void G1CollectedHeap::free_region(HeapRegion* hr,
5856 FreeRegionList* free_list,
5857 bool par,
5858 bool locked) {
5859 assert(!hr->is_free(), "the region should not be free");
5860 assert(!hr->is_empty(), "the region should not be empty");
5861 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5862 assert(free_list != NULL, "pre-condition");
5864 if (G1VerifyBitmaps) {
5865 MemRegion mr(hr->bottom(), hr->end());
5866 concurrent_mark()->clearRangePrevBitmap(mr);
5867 }
5869 // Clear the card counts for this region.
5870 // Note: we only need to do this if the region is not young
5871 // (since we don't refine cards in young regions).
5872 if (!hr->is_young()) {
5873 _cg1r->hot_card_cache()->reset_card_counts(hr);
5874 }
5875 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5876 free_list->add_ordered(hr);
5877 }
5879 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5880 FreeRegionList* free_list,
5881 bool par) {
5882 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5883 assert(free_list != NULL, "pre-condition");
5885 size_t hr_capacity = hr->capacity();
5886 // We need to read this before we make the region non-humongous,
5887 // otherwise the information will be gone.
5888 uint last_index = hr->last_hc_index();
5889 hr->clear_humongous();
5890 free_region(hr, free_list, par);
5892 uint i = hr->hrm_index() + 1;
5893 while (i < last_index) {
5894 HeapRegion* curr_hr = region_at(i);
5895 assert(curr_hr->continuesHumongous(), "invariant");
5896 curr_hr->clear_humongous();
5897 free_region(curr_hr, free_list, par);
5898 i += 1;
5899 }
5900 }
5902 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5903 const HeapRegionSetCount& humongous_regions_removed) {
5904 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5905 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5906 _old_set.bulk_remove(old_regions_removed);
5907 _humongous_set.bulk_remove(humongous_regions_removed);
5908 }
5910 }
5912 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5913 assert(list != NULL, "list can't be null");
5914 if (!list->is_empty()) {
5915 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5916 _hrm.insert_list_into_free_list(list);
5917 }
5918 }
5920 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5921 _allocator->decrease_used(bytes);
5922 }
5924 class G1ParCleanupCTTask : public AbstractGangTask {
5925 G1SATBCardTableModRefBS* _ct_bs;
5926 G1CollectedHeap* _g1h;
5927 HeapRegion* volatile _su_head;
5928 public:
5929 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5930 G1CollectedHeap* g1h) :
5931 AbstractGangTask("G1 Par Cleanup CT Task"),
5932 _ct_bs(ct_bs), _g1h(g1h) { }
5934 void work(uint worker_id) {
5935 HeapRegion* r;
5936 while (r = _g1h->pop_dirty_cards_region()) {
5937 clear_cards(r);
5938 }
5939 }
5941 void clear_cards(HeapRegion* r) {
5942 // Cards of the survivors should have already been dirtied.
5943 if (!r->is_survivor()) {
5944 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5945 }
5946 }
5947 };
5949 #ifndef PRODUCT
5950 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5951 G1CollectedHeap* _g1h;
5952 G1SATBCardTableModRefBS* _ct_bs;
5953 public:
5954 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5955 : _g1h(g1h), _ct_bs(ct_bs) { }
5956 virtual bool doHeapRegion(HeapRegion* r) {
5957 if (r->is_survivor()) {
5958 _g1h->verify_dirty_region(r);
5959 } else {
5960 _g1h->verify_not_dirty_region(r);
5961 }
5962 return false;
5963 }
5964 };
5966 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5967 // All of the region should be clean.
5968 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5969 MemRegion mr(hr->bottom(), hr->end());
5970 ct_bs->verify_not_dirty_region(mr);
5971 }
5973 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5974 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5975 // dirty allocated blocks as they allocate them. The thread that
5976 // retires each region and replaces it with a new one will do a
5977 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5978 // not dirty that area (one less thing to have to do while holding
5979 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5980 // is dirty.
5981 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5982 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5983 if (hr->is_young()) {
5984 ct_bs->verify_g1_young_region(mr);
5985 } else {
5986 ct_bs->verify_dirty_region(mr);
5987 }
5988 }
5990 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5991 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5992 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5993 verify_dirty_region(hr);
5994 }
5995 }
5997 void G1CollectedHeap::verify_dirty_young_regions() {
5998 verify_dirty_young_list(_young_list->first_region());
5999 }
6001 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6002 HeapWord* tams, HeapWord* end) {
6003 guarantee(tams <= end,
6004 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6005 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6006 if (result < end) {
6007 gclog_or_tty->cr();
6008 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6009 bitmap_name, result);
6010 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6011 bitmap_name, tams, end);
6012 return false;
6013 }
6014 return true;
6015 }
6017 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6018 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6019 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6021 HeapWord* bottom = hr->bottom();
6022 HeapWord* ptams = hr->prev_top_at_mark_start();
6023 HeapWord* ntams = hr->next_top_at_mark_start();
6024 HeapWord* end = hr->end();
6026 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6028 bool res_n = true;
6029 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6030 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6031 // if we happen to be in that state.
6032 if (mark_in_progress() || !_cmThread->in_progress()) {
6033 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6034 }
6035 if (!res_p || !res_n) {
6036 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6037 HR_FORMAT_PARAMS(hr));
6038 gclog_or_tty->print_cr("#### Caller: %s", caller);
6039 return false;
6040 }
6041 return true;
6042 }
6044 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6045 if (!G1VerifyBitmaps) return;
6047 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6048 }
6050 class G1VerifyBitmapClosure : public HeapRegionClosure {
6051 private:
6052 const char* _caller;
6053 G1CollectedHeap* _g1h;
6054 bool _failures;
6056 public:
6057 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6058 _caller(caller), _g1h(g1h), _failures(false) { }
6060 bool failures() { return _failures; }
6062 virtual bool doHeapRegion(HeapRegion* hr) {
6063 if (hr->continuesHumongous()) return false;
6065 bool result = _g1h->verify_bitmaps(_caller, hr);
6066 if (!result) {
6067 _failures = true;
6068 }
6069 return false;
6070 }
6071 };
6073 void G1CollectedHeap::check_bitmaps(const char* caller) {
6074 if (!G1VerifyBitmaps) return;
6076 G1VerifyBitmapClosure cl(caller, this);
6077 heap_region_iterate(&cl);
6078 guarantee(!cl.failures(), "bitmap verification");
6079 }
6081 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
6082 private:
6083 bool _failures;
6084 public:
6085 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
6087 virtual bool doHeapRegion(HeapRegion* hr) {
6088 uint i = hr->hrm_index();
6089 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
6090 if (hr->isHumongous()) {
6091 if (hr->in_collection_set()) {
6092 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
6093 _failures = true;
6094 return true;
6095 }
6096 if (cset_state.is_in_cset()) {
6097 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
6098 _failures = true;
6099 return true;
6100 }
6101 if (hr->continuesHumongous() && cset_state.is_humongous()) {
6102 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
6103 _failures = true;
6104 return true;
6105 }
6106 } else {
6107 if (cset_state.is_humongous()) {
6108 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
6109 _failures = true;
6110 return true;
6111 }
6112 if (hr->in_collection_set() != cset_state.is_in_cset()) {
6113 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6114 hr->in_collection_set(), cset_state.value(), i);
6115 _failures = true;
6116 return true;
6117 }
6118 if (cset_state.is_in_cset()) {
6119 if (hr->is_young() != (cset_state.is_young())) {
6120 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6121 hr->is_young(), cset_state.value(), i);
6122 _failures = true;
6123 return true;
6124 }
6125 if (hr->is_old() != (cset_state.is_old())) {
6126 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6127 hr->is_old(), cset_state.value(), i);
6128 _failures = true;
6129 return true;
6130 }
6131 }
6132 }
6133 return false;
6134 }
6136 bool failures() const { return _failures; }
6137 };
6139 bool G1CollectedHeap::check_cset_fast_test() {
6140 G1CheckCSetFastTableClosure cl;
6141 _hrm.iterate(&cl);
6142 return !cl.failures();
6143 }
6144 #endif // PRODUCT
6146 void G1CollectedHeap::cleanUpCardTable() {
6147 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6148 double start = os::elapsedTime();
6150 {
6151 // Iterate over the dirty cards region list.
6152 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6154 if (G1CollectedHeap::use_parallel_gc_threads()) {
6155 set_par_threads();
6156 workers()->run_task(&cleanup_task);
6157 set_par_threads(0);
6158 } else {
6159 while (_dirty_cards_region_list) {
6160 HeapRegion* r = _dirty_cards_region_list;
6161 cleanup_task.clear_cards(r);
6162 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6163 if (_dirty_cards_region_list == r) {
6164 // The last region.
6165 _dirty_cards_region_list = NULL;
6166 }
6167 r->set_next_dirty_cards_region(NULL);
6168 }
6169 }
6170 #ifndef PRODUCT
6171 if (G1VerifyCTCleanup || VerifyAfterGC) {
6172 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6173 heap_region_iterate(&cleanup_verifier);
6174 }
6175 #endif
6176 }
6178 double elapsed = os::elapsedTime() - start;
6179 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6180 }
6182 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6183 size_t pre_used = 0;
6184 FreeRegionList local_free_list("Local List for CSet Freeing");
6186 double young_time_ms = 0.0;
6187 double non_young_time_ms = 0.0;
6189 // Since the collection set is a superset of the the young list,
6190 // all we need to do to clear the young list is clear its
6191 // head and length, and unlink any young regions in the code below
6192 _young_list->clear();
6194 G1CollectorPolicy* policy = g1_policy();
6196 double start_sec = os::elapsedTime();
6197 bool non_young = true;
6199 HeapRegion* cur = cs_head;
6200 int age_bound = -1;
6201 size_t rs_lengths = 0;
6203 while (cur != NULL) {
6204 assert(!is_on_master_free_list(cur), "sanity");
6205 if (non_young) {
6206 if (cur->is_young()) {
6207 double end_sec = os::elapsedTime();
6208 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6209 non_young_time_ms += elapsed_ms;
6211 start_sec = os::elapsedTime();
6212 non_young = false;
6213 }
6214 } else {
6215 if (!cur->is_young()) {
6216 double end_sec = os::elapsedTime();
6217 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6218 young_time_ms += elapsed_ms;
6220 start_sec = os::elapsedTime();
6221 non_young = true;
6222 }
6223 }
6225 rs_lengths += cur->rem_set()->occupied_locked();
6227 HeapRegion* next = cur->next_in_collection_set();
6228 assert(cur->in_collection_set(), "bad CS");
6229 cur->set_next_in_collection_set(NULL);
6230 cur->set_in_collection_set(false);
6232 if (cur->is_young()) {
6233 int index = cur->young_index_in_cset();
6234 assert(index != -1, "invariant");
6235 assert((uint) index < policy->young_cset_region_length(), "invariant");
6236 size_t words_survived = _surviving_young_words[index];
6237 cur->record_surv_words_in_group(words_survived);
6239 // At this point the we have 'popped' cur from the collection set
6240 // (linked via next_in_collection_set()) but it is still in the
6241 // young list (linked via next_young_region()). Clear the
6242 // _next_young_region field.
6243 cur->set_next_young_region(NULL);
6244 } else {
6245 int index = cur->young_index_in_cset();
6246 assert(index == -1, "invariant");
6247 }
6249 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6250 (!cur->is_young() && cur->young_index_in_cset() == -1),
6251 "invariant" );
6253 if (!cur->evacuation_failed()) {
6254 MemRegion used_mr = cur->used_region();
6256 // And the region is empty.
6257 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6258 pre_used += cur->used();
6259 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6260 } else {
6261 cur->uninstall_surv_rate_group();
6262 if (cur->is_young()) {
6263 cur->set_young_index_in_cset(-1);
6264 }
6265 cur->set_evacuation_failed(false);
6266 // The region is now considered to be old.
6267 cur->set_old();
6268 _old_set.add(cur);
6269 evacuation_info.increment_collectionset_used_after(cur->used());
6270 }
6271 cur = next;
6272 }
6274 evacuation_info.set_regions_freed(local_free_list.length());
6275 policy->record_max_rs_lengths(rs_lengths);
6276 policy->cset_regions_freed();
6278 double end_sec = os::elapsedTime();
6279 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6281 if (non_young) {
6282 non_young_time_ms += elapsed_ms;
6283 } else {
6284 young_time_ms += elapsed_ms;
6285 }
6287 prepend_to_freelist(&local_free_list);
6288 decrement_summary_bytes(pre_used);
6289 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6290 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6291 }
6293 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6294 private:
6295 FreeRegionList* _free_region_list;
6296 HeapRegionSet* _proxy_set;
6297 HeapRegionSetCount _humongous_regions_removed;
6298 size_t _freed_bytes;
6299 public:
6301 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6302 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6303 }
6305 virtual bool doHeapRegion(HeapRegion* r) {
6306 if (!r->startsHumongous()) {
6307 return false;
6308 }
6310 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6312 oop obj = (oop)r->bottom();
6313 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6315 // The following checks whether the humongous object is live are sufficient.
6316 // The main additional check (in addition to having a reference from the roots
6317 // or the young gen) is whether the humongous object has a remembered set entry.
6318 //
6319 // A humongous object cannot be live if there is no remembered set for it
6320 // because:
6321 // - there can be no references from within humongous starts regions referencing
6322 // the object because we never allocate other objects into them.
6323 // (I.e. there are no intra-region references that may be missed by the
6324 // remembered set)
6325 // - as soon there is a remembered set entry to the humongous starts region
6326 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6327 // until the end of a concurrent mark.
6328 //
6329 // It is not required to check whether the object has been found dead by marking
6330 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6331 // all objects allocated during that time are considered live.
6332 // SATB marking is even more conservative than the remembered set.
6333 // So if at this point in the collection there is no remembered set entry,
6334 // nobody has a reference to it.
6335 // At the start of collection we flush all refinement logs, and remembered sets
6336 // are completely up-to-date wrt to references to the humongous object.
6337 //
6338 // Other implementation considerations:
6339 // - never consider object arrays at this time because they would pose
6340 // considerable effort for cleaning up the the remembered sets. This is
6341 // required because stale remembered sets might reference locations that
6342 // are currently allocated into.
6343 uint region_idx = r->hrm_index();
6344 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6345 !r->rem_set()->is_empty()) {
6347 if (G1TraceEagerReclaimHumongousObjects) {
6348 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6349 region_idx,
6350 obj->size()*HeapWordSize,
6351 r->bottom(),
6352 r->region_num(),
6353 r->rem_set()->occupied(),
6354 r->rem_set()->strong_code_roots_list_length(),
6355 next_bitmap->isMarked(r->bottom()),
6356 g1h->is_humongous_reclaim_candidate(region_idx),
6357 obj->is_typeArray()
6358 );
6359 }
6361 return false;
6362 }
6364 guarantee(obj->is_typeArray(),
6365 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6366 PTR_FORMAT " is not.",
6367 r->bottom()));
6369 if (G1TraceEagerReclaimHumongousObjects) {
6370 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6371 region_idx,
6372 obj->size()*HeapWordSize,
6373 r->bottom(),
6374 r->region_num(),
6375 r->rem_set()->occupied(),
6376 r->rem_set()->strong_code_roots_list_length(),
6377 next_bitmap->isMarked(r->bottom()),
6378 g1h->is_humongous_reclaim_candidate(region_idx),
6379 obj->is_typeArray()
6380 );
6381 }
6382 // Need to clear mark bit of the humongous object if already set.
6383 if (next_bitmap->isMarked(r->bottom())) {
6384 next_bitmap->clear(r->bottom());
6385 }
6386 _freed_bytes += r->used();
6387 r->set_containing_set(NULL);
6388 _humongous_regions_removed.increment(1u, r->capacity());
6389 g1h->free_humongous_region(r, _free_region_list, false);
6391 return false;
6392 }
6394 HeapRegionSetCount& humongous_free_count() {
6395 return _humongous_regions_removed;
6396 }
6398 size_t bytes_freed() const {
6399 return _freed_bytes;
6400 }
6402 size_t humongous_reclaimed() const {
6403 return _humongous_regions_removed.length();
6404 }
6405 };
6407 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6408 assert_at_safepoint(true);
6410 if (!G1EagerReclaimHumongousObjects ||
6411 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6412 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6413 return;
6414 }
6416 double start_time = os::elapsedTime();
6418 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6420 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6421 heap_region_iterate(&cl);
6423 HeapRegionSetCount empty_set;
6424 remove_from_old_sets(empty_set, cl.humongous_free_count());
6426 G1HRPrinter* hr_printer = _g1h->hr_printer();
6427 if (hr_printer->is_active()) {
6428 FreeRegionListIterator iter(&local_cleanup_list);
6429 while (iter.more_available()) {
6430 HeapRegion* hr = iter.get_next();
6431 hr_printer->cleanup(hr);
6432 }
6433 }
6435 prepend_to_freelist(&local_cleanup_list);
6436 decrement_summary_bytes(cl.bytes_freed());
6438 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6439 cl.humongous_reclaimed());
6440 }
6442 // This routine is similar to the above but does not record
6443 // any policy statistics or update free lists; we are abandoning
6444 // the current incremental collection set in preparation of a
6445 // full collection. After the full GC we will start to build up
6446 // the incremental collection set again.
6447 // This is only called when we're doing a full collection
6448 // and is immediately followed by the tearing down of the young list.
6450 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6451 HeapRegion* cur = cs_head;
6453 while (cur != NULL) {
6454 HeapRegion* next = cur->next_in_collection_set();
6455 assert(cur->in_collection_set(), "bad CS");
6456 cur->set_next_in_collection_set(NULL);
6457 cur->set_in_collection_set(false);
6458 cur->set_young_index_in_cset(-1);
6459 cur = next;
6460 }
6461 }
6463 void G1CollectedHeap::set_free_regions_coming() {
6464 if (G1ConcRegionFreeingVerbose) {
6465 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6466 "setting free regions coming");
6467 }
6469 assert(!free_regions_coming(), "pre-condition");
6470 _free_regions_coming = true;
6471 }
6473 void G1CollectedHeap::reset_free_regions_coming() {
6474 assert(free_regions_coming(), "pre-condition");
6476 {
6477 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6478 _free_regions_coming = false;
6479 SecondaryFreeList_lock->notify_all();
6480 }
6482 if (G1ConcRegionFreeingVerbose) {
6483 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6484 "reset free regions coming");
6485 }
6486 }
6488 void G1CollectedHeap::wait_while_free_regions_coming() {
6489 // Most of the time we won't have to wait, so let's do a quick test
6490 // first before we take the lock.
6491 if (!free_regions_coming()) {
6492 return;
6493 }
6495 if (G1ConcRegionFreeingVerbose) {
6496 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6497 "waiting for free regions");
6498 }
6500 {
6501 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6502 while (free_regions_coming()) {
6503 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6504 }
6505 }
6507 if (G1ConcRegionFreeingVerbose) {
6508 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6509 "done waiting for free regions");
6510 }
6511 }
6513 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6514 assert(heap_lock_held_for_gc(),
6515 "the heap lock should already be held by or for this thread");
6516 _young_list->push_region(hr);
6517 }
6519 class NoYoungRegionsClosure: public HeapRegionClosure {
6520 private:
6521 bool _success;
6522 public:
6523 NoYoungRegionsClosure() : _success(true) { }
6524 bool doHeapRegion(HeapRegion* r) {
6525 if (r->is_young()) {
6526 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6527 r->bottom(), r->end());
6528 _success = false;
6529 }
6530 return false;
6531 }
6532 bool success() { return _success; }
6533 };
6535 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6536 bool ret = _young_list->check_list_empty(check_sample);
6538 if (check_heap) {
6539 NoYoungRegionsClosure closure;
6540 heap_region_iterate(&closure);
6541 ret = ret && closure.success();
6542 }
6544 return ret;
6545 }
6547 class TearDownRegionSetsClosure : public HeapRegionClosure {
6548 private:
6549 HeapRegionSet *_old_set;
6551 public:
6552 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6554 bool doHeapRegion(HeapRegion* r) {
6555 if (r->is_old()) {
6556 _old_set->remove(r);
6557 } else {
6558 // We ignore free regions, we'll empty the free list afterwards.
6559 // We ignore young regions, we'll empty the young list afterwards.
6560 // We ignore humongous regions, we're not tearing down the
6561 // humongous regions set.
6562 assert(r->is_free() || r->is_young() || r->isHumongous(),
6563 "it cannot be another type");
6564 }
6565 return false;
6566 }
6568 ~TearDownRegionSetsClosure() {
6569 assert(_old_set->is_empty(), "post-condition");
6570 }
6571 };
6573 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6574 assert_at_safepoint(true /* should_be_vm_thread */);
6576 if (!free_list_only) {
6577 TearDownRegionSetsClosure cl(&_old_set);
6578 heap_region_iterate(&cl);
6580 // Note that emptying the _young_list is postponed and instead done as
6581 // the first step when rebuilding the regions sets again. The reason for
6582 // this is that during a full GC string deduplication needs to know if
6583 // a collected region was young or old when the full GC was initiated.
6584 }
6585 _hrm.remove_all_free_regions();
6586 }
6588 class RebuildRegionSetsClosure : public HeapRegionClosure {
6589 private:
6590 bool _free_list_only;
6591 HeapRegionSet* _old_set;
6592 HeapRegionManager* _hrm;
6593 size_t _total_used;
6595 public:
6596 RebuildRegionSetsClosure(bool free_list_only,
6597 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6598 _free_list_only(free_list_only),
6599 _old_set(old_set), _hrm(hrm), _total_used(0) {
6600 assert(_hrm->num_free_regions() == 0, "pre-condition");
6601 if (!free_list_only) {
6602 assert(_old_set->is_empty(), "pre-condition");
6603 }
6604 }
6606 bool doHeapRegion(HeapRegion* r) {
6607 if (r->continuesHumongous()) {
6608 return false;
6609 }
6611 if (r->is_empty()) {
6612 // Add free regions to the free list
6613 r->set_free();
6614 r->set_allocation_context(AllocationContext::system());
6615 _hrm->insert_into_free_list(r);
6616 } else if (!_free_list_only) {
6617 assert(!r->is_young(), "we should not come across young regions");
6619 if (r->isHumongous()) {
6620 // We ignore humongous regions, we left the humongous set unchanged
6621 } else {
6622 // Objects that were compacted would have ended up on regions
6623 // that were previously old or free.
6624 assert(r->is_free() || r->is_old(), "invariant");
6625 // We now consider them old, so register as such.
6626 r->set_old();
6627 _old_set->add(r);
6628 }
6629 _total_used += r->used();
6630 }
6632 return false;
6633 }
6635 size_t total_used() {
6636 return _total_used;
6637 }
6638 };
6640 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6641 assert_at_safepoint(true /* should_be_vm_thread */);
6643 if (!free_list_only) {
6644 _young_list->empty_list();
6645 }
6647 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6648 heap_region_iterate(&cl);
6650 if (!free_list_only) {
6651 _allocator->set_used(cl.total_used());
6652 }
6653 assert(_allocator->used_unlocked() == recalculate_used(),
6654 err_msg("inconsistent _allocator->used_unlocked(), "
6655 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6656 _allocator->used_unlocked(), recalculate_used()));
6657 }
6659 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6660 _refine_cte_cl->set_concurrent(concurrent);
6661 }
6663 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6664 HeapRegion* hr = heap_region_containing(p);
6665 return hr->is_in(p);
6666 }
6668 // Methods for the mutator alloc region
6670 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6671 bool force) {
6672 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6673 assert(!force || g1_policy()->can_expand_young_list(),
6674 "if force is true we should be able to expand the young list");
6675 bool young_list_full = g1_policy()->is_young_list_full();
6676 if (force || !young_list_full) {
6677 HeapRegion* new_alloc_region = new_region(word_size,
6678 false /* is_old */,
6679 false /* do_expand */);
6680 if (new_alloc_region != NULL) {
6681 set_region_short_lived_locked(new_alloc_region);
6682 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6683 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6684 return new_alloc_region;
6685 }
6686 }
6687 return NULL;
6688 }
6690 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6691 size_t allocated_bytes) {
6692 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6693 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6695 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6696 _allocator->increase_used(allocated_bytes);
6697 _hr_printer.retire(alloc_region);
6698 // We update the eden sizes here, when the region is retired,
6699 // instead of when it's allocated, since this is the point that its
6700 // used space has been recored in _summary_bytes_used.
6701 g1mm()->update_eden_size();
6702 }
6704 void G1CollectedHeap::set_par_threads() {
6705 // Don't change the number of workers. Use the value previously set
6706 // in the workgroup.
6707 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6708 uint n_workers = workers()->active_workers();
6709 assert(UseDynamicNumberOfGCThreads ||
6710 n_workers == workers()->total_workers(),
6711 "Otherwise should be using the total number of workers");
6712 if (n_workers == 0) {
6713 assert(false, "Should have been set in prior evacuation pause.");
6714 n_workers = ParallelGCThreads;
6715 workers()->set_active_workers(n_workers);
6716 }
6717 set_par_threads(n_workers);
6718 }
6720 // Methods for the GC alloc regions
6722 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6723 uint count,
6724 InCSetState dest) {
6725 assert(FreeList_lock->owned_by_self(), "pre-condition");
6727 if (count < g1_policy()->max_regions(dest)) {
6728 const bool is_survivor = (dest.is_young());
6729 HeapRegion* new_alloc_region = new_region(word_size,
6730 !is_survivor,
6731 true /* do_expand */);
6732 if (new_alloc_region != NULL) {
6733 // We really only need to do this for old regions given that we
6734 // should never scan survivors. But it doesn't hurt to do it
6735 // for survivors too.
6736 new_alloc_region->record_timestamp();
6737 if (is_survivor) {
6738 new_alloc_region->set_survivor();
6739 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6740 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6741 } else {
6742 new_alloc_region->set_old();
6743 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6744 check_bitmaps("Old Region Allocation", new_alloc_region);
6745 }
6746 bool during_im = g1_policy()->during_initial_mark_pause();
6747 new_alloc_region->note_start_of_copying(during_im);
6748 return new_alloc_region;
6749 }
6750 }
6751 return NULL;
6752 }
6754 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6755 size_t allocated_bytes,
6756 InCSetState dest) {
6757 bool during_im = g1_policy()->during_initial_mark_pause();
6758 alloc_region->note_end_of_copying(during_im);
6759 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6760 if (dest.is_young()) {
6761 young_list()->add_survivor_region(alloc_region);
6762 } else {
6763 _old_set.add(alloc_region);
6764 }
6765 _hr_printer.retire(alloc_region);
6766 }
6768 // Heap region set verification
6770 class VerifyRegionListsClosure : public HeapRegionClosure {
6771 private:
6772 HeapRegionSet* _old_set;
6773 HeapRegionSet* _humongous_set;
6774 HeapRegionManager* _hrm;
6776 public:
6777 HeapRegionSetCount _old_count;
6778 HeapRegionSetCount _humongous_count;
6779 HeapRegionSetCount _free_count;
6781 VerifyRegionListsClosure(HeapRegionSet* old_set,
6782 HeapRegionSet* humongous_set,
6783 HeapRegionManager* hrm) :
6784 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6785 _old_count(), _humongous_count(), _free_count(){ }
6787 bool doHeapRegion(HeapRegion* hr) {
6788 if (hr->continuesHumongous()) {
6789 return false;
6790 }
6792 if (hr->is_young()) {
6793 // TODO
6794 } else if (hr->startsHumongous()) {
6795 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6796 _humongous_count.increment(1u, hr->capacity());
6797 } else if (hr->is_empty()) {
6798 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6799 _free_count.increment(1u, hr->capacity());
6800 } else if (hr->is_old()) {
6801 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6802 _old_count.increment(1u, hr->capacity());
6803 } else {
6804 ShouldNotReachHere();
6805 }
6806 return false;
6807 }
6809 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6810 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6811 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6812 old_set->total_capacity_bytes(), _old_count.capacity()));
6814 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6815 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6816 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6818 guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
6819 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6820 free_list->total_capacity_bytes(), _free_count.capacity()));
6821 }
6822 };
6824 void G1CollectedHeap::verify_region_sets() {
6825 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6827 // First, check the explicit lists.
6828 _hrm.verify();
6829 {
6830 // Given that a concurrent operation might be adding regions to
6831 // the secondary free list we have to take the lock before
6832 // verifying it.
6833 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6834 _secondary_free_list.verify_list();
6835 }
6837 // If a concurrent region freeing operation is in progress it will
6838 // be difficult to correctly attributed any free regions we come
6839 // across to the correct free list given that they might belong to
6840 // one of several (free_list, secondary_free_list, any local lists,
6841 // etc.). So, if that's the case we will skip the rest of the
6842 // verification operation. Alternatively, waiting for the concurrent
6843 // operation to complete will have a non-trivial effect on the GC's
6844 // operation (no concurrent operation will last longer than the
6845 // interval between two calls to verification) and it might hide
6846 // any issues that we would like to catch during testing.
6847 if (free_regions_coming()) {
6848 return;
6849 }
6851 // Make sure we append the secondary_free_list on the free_list so
6852 // that all free regions we will come across can be safely
6853 // attributed to the free_list.
6854 append_secondary_free_list_if_not_empty_with_lock();
6856 // Finally, make sure that the region accounting in the lists is
6857 // consistent with what we see in the heap.
6859 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6860 heap_region_iterate(&cl);
6861 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6862 }
6864 // Optimized nmethod scanning
6866 class RegisterNMethodOopClosure: public OopClosure {
6867 G1CollectedHeap* _g1h;
6868 nmethod* _nm;
6870 template <class T> void do_oop_work(T* p) {
6871 T heap_oop = oopDesc::load_heap_oop(p);
6872 if (!oopDesc::is_null(heap_oop)) {
6873 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6874 HeapRegion* hr = _g1h->heap_region_containing(obj);
6875 assert(!hr->continuesHumongous(),
6876 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6877 " starting at "HR_FORMAT,
6878 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6880 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6881 hr->add_strong_code_root_locked(_nm);
6882 }
6883 }
6885 public:
6886 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6887 _g1h(g1h), _nm(nm) {}
6889 void do_oop(oop* p) { do_oop_work(p); }
6890 void do_oop(narrowOop* p) { do_oop_work(p); }
6891 };
6893 class UnregisterNMethodOopClosure: public OopClosure {
6894 G1CollectedHeap* _g1h;
6895 nmethod* _nm;
6897 template <class T> void do_oop_work(T* p) {
6898 T heap_oop = oopDesc::load_heap_oop(p);
6899 if (!oopDesc::is_null(heap_oop)) {
6900 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6901 HeapRegion* hr = _g1h->heap_region_containing(obj);
6902 assert(!hr->continuesHumongous(),
6903 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6904 " starting at "HR_FORMAT,
6905 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6907 hr->remove_strong_code_root(_nm);
6908 }
6909 }
6911 public:
6912 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6913 _g1h(g1h), _nm(nm) {}
6915 void do_oop(oop* p) { do_oop_work(p); }
6916 void do_oop(narrowOop* p) { do_oop_work(p); }
6917 };
6919 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6920 CollectedHeap::register_nmethod(nm);
6922 guarantee(nm != NULL, "sanity");
6923 RegisterNMethodOopClosure reg_cl(this, nm);
6924 nm->oops_do(®_cl);
6925 }
6927 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6928 CollectedHeap::unregister_nmethod(nm);
6930 guarantee(nm != NULL, "sanity");
6931 UnregisterNMethodOopClosure reg_cl(this, nm);
6932 nm->oops_do(®_cl, true);
6933 }
6935 void G1CollectedHeap::purge_code_root_memory() {
6936 double purge_start = os::elapsedTime();
6937 G1CodeRootSet::purge();
6938 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6939 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6940 }
6942 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6943 G1CollectedHeap* _g1h;
6945 public:
6946 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6947 _g1h(g1h) {}
6949 void do_code_blob(CodeBlob* cb) {
6950 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6951 if (nm == NULL) {
6952 return;
6953 }
6955 if (ScavengeRootsInCode) {
6956 _g1h->register_nmethod(nm);
6957 }
6958 }
6959 };
6961 void G1CollectedHeap::rebuild_strong_code_roots() {
6962 RebuildStrongCodeRootClosure blob_cl(this);
6963 CodeCache::blobs_do(&blob_cl);
6964 }