Mon, 09 Jan 2012 23:50:41 -0500
7125281: G1: heap expansion code is replicated
Reviewed-by: brutisso, johnc
1 /*
2 * Copyright (c) 2001, 2012, 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
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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).
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23 */
25 #include "precompiled.hpp"
26 #include "code/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
35 #include "gc_implementation/g1/g1EvacFailure.hpp"
36 #include "gc_implementation/g1/g1MarkSweep.hpp"
37 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
38 #include "gc_implementation/g1/g1RemSet.inline.hpp"
39 #include "gc_implementation/g1/heapRegionRemSet.hpp"
40 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
41 #include "gc_implementation/g1/vm_operations_g1.hpp"
42 #include "gc_implementation/shared/isGCActiveMark.hpp"
43 #include "memory/gcLocker.inline.hpp"
44 #include "memory/genOopClosures.inline.hpp"
45 #include "memory/generationSpec.hpp"
46 #include "memory/referenceProcessor.hpp"
47 #include "oops/oop.inline.hpp"
48 #include "oops/oop.pcgc.inline.hpp"
49 #include "runtime/aprofiler.hpp"
50 #include "runtime/vmThread.hpp"
52 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
54 // turn it on so that the contents of the young list (scan-only /
55 // to-be-collected) are printed at "strategic" points before / during
56 // / after the collection --- this is useful for debugging
57 #define YOUNG_LIST_VERBOSE 0
58 // CURRENT STATUS
59 // This file is under construction. Search for "FIXME".
61 // INVARIANTS/NOTES
62 //
63 // All allocation activity covered by the G1CollectedHeap interface is
64 // serialized by acquiring the HeapLock. This happens in mem_allocate
65 // and allocate_new_tlab, which are the "entry" points to the
66 // allocation code from the rest of the JVM. (Note that this does not
67 // apply to TLAB allocation, which is not part of this interface: it
68 // is done by clients of this interface.)
70 // Notes on implementation of parallelism in different tasks.
71 //
72 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
73 // The number of GC workers is passed to heap_region_par_iterate_chunked().
74 // It does use run_task() which sets _n_workers in the task.
75 // G1ParTask executes g1_process_strong_roots() ->
76 // SharedHeap::process_strong_roots() which calls eventuall to
77 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
78 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
79 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
80 //
82 // Local to this file.
84 class RefineCardTableEntryClosure: public CardTableEntryClosure {
85 SuspendibleThreadSet* _sts;
86 G1RemSet* _g1rs;
87 ConcurrentG1Refine* _cg1r;
88 bool _concurrent;
89 public:
90 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
91 G1RemSet* g1rs,
92 ConcurrentG1Refine* cg1r) :
93 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
94 {}
95 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
96 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
97 // This path is executed by the concurrent refine or mutator threads,
98 // concurrently, and so we do not care if card_ptr contains references
99 // that point into the collection set.
100 assert(!oops_into_cset, "should be");
102 if (_concurrent && _sts->should_yield()) {
103 // Caller will actually yield.
104 return false;
105 }
106 // Otherwise, we finished successfully; return true.
107 return true;
108 }
109 void set_concurrent(bool b) { _concurrent = b; }
110 };
113 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
114 int _calls;
115 G1CollectedHeap* _g1h;
116 CardTableModRefBS* _ctbs;
117 int _histo[256];
118 public:
119 ClearLoggedCardTableEntryClosure() :
120 _calls(0)
121 {
122 _g1h = G1CollectedHeap::heap();
123 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
124 for (int i = 0; i < 256; i++) _histo[i] = 0;
125 }
126 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
127 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
128 _calls++;
129 unsigned char* ujb = (unsigned char*)card_ptr;
130 int ind = (int)(*ujb);
131 _histo[ind]++;
132 *card_ptr = -1;
133 }
134 return true;
135 }
136 int calls() { return _calls; }
137 void print_histo() {
138 gclog_or_tty->print_cr("Card table value histogram:");
139 for (int i = 0; i < 256; i++) {
140 if (_histo[i] != 0) {
141 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
142 }
143 }
144 }
145 };
147 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
148 int _calls;
149 G1CollectedHeap* _g1h;
150 CardTableModRefBS* _ctbs;
151 public:
152 RedirtyLoggedCardTableEntryClosure() :
153 _calls(0)
154 {
155 _g1h = G1CollectedHeap::heap();
156 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
157 }
158 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
159 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
160 _calls++;
161 *card_ptr = 0;
162 }
163 return true;
164 }
165 int calls() { return _calls; }
166 };
168 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
169 public:
170 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
171 *card_ptr = CardTableModRefBS::dirty_card_val();
172 return true;
173 }
174 };
176 YoungList::YoungList(G1CollectedHeap* g1h)
177 : _g1h(g1h), _head(NULL),
178 _length(0),
179 _last_sampled_rs_lengths(0),
180 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
181 {
182 guarantee( check_list_empty(false), "just making sure..." );
183 }
185 void YoungList::push_region(HeapRegion *hr) {
186 assert(!hr->is_young(), "should not already be young");
187 assert(hr->get_next_young_region() == NULL, "cause it should!");
189 hr->set_next_young_region(_head);
190 _head = hr;
192 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
193 ++_length;
194 }
196 void YoungList::add_survivor_region(HeapRegion* hr) {
197 assert(hr->is_survivor(), "should be flagged as survivor region");
198 assert(hr->get_next_young_region() == NULL, "cause it should!");
200 hr->set_next_young_region(_survivor_head);
201 if (_survivor_head == NULL) {
202 _survivor_tail = hr;
203 }
204 _survivor_head = hr;
205 ++_survivor_length;
206 }
208 void YoungList::empty_list(HeapRegion* list) {
209 while (list != NULL) {
210 HeapRegion* next = list->get_next_young_region();
211 list->set_next_young_region(NULL);
212 list->uninstall_surv_rate_group();
213 list->set_not_young();
214 list = next;
215 }
216 }
218 void YoungList::empty_list() {
219 assert(check_list_well_formed(), "young list should be well formed");
221 empty_list(_head);
222 _head = NULL;
223 _length = 0;
225 empty_list(_survivor_head);
226 _survivor_head = NULL;
227 _survivor_tail = NULL;
228 _survivor_length = 0;
230 _last_sampled_rs_lengths = 0;
232 assert(check_list_empty(false), "just making sure...");
233 }
235 bool YoungList::check_list_well_formed() {
236 bool ret = true;
238 size_t length = 0;
239 HeapRegion* curr = _head;
240 HeapRegion* last = NULL;
241 while (curr != NULL) {
242 if (!curr->is_young()) {
243 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
244 "incorrectly tagged (y: %d, surv: %d)",
245 curr->bottom(), curr->end(),
246 curr->is_young(), curr->is_survivor());
247 ret = false;
248 }
249 ++length;
250 last = curr;
251 curr = curr->get_next_young_region();
252 }
253 ret = ret && (length == _length);
255 if (!ret) {
256 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
257 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
258 length, _length);
259 }
261 return ret;
262 }
264 bool YoungList::check_list_empty(bool check_sample) {
265 bool ret = true;
267 if (_length != 0) {
268 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
269 _length);
270 ret = false;
271 }
272 if (check_sample && _last_sampled_rs_lengths != 0) {
273 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
274 ret = false;
275 }
276 if (_head != NULL) {
277 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
278 ret = false;
279 }
280 if (!ret) {
281 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
282 }
284 return ret;
285 }
287 void
288 YoungList::rs_length_sampling_init() {
289 _sampled_rs_lengths = 0;
290 _curr = _head;
291 }
293 bool
294 YoungList::rs_length_sampling_more() {
295 return _curr != NULL;
296 }
298 void
299 YoungList::rs_length_sampling_next() {
300 assert( _curr != NULL, "invariant" );
301 size_t rs_length = _curr->rem_set()->occupied();
303 _sampled_rs_lengths += rs_length;
305 // The current region may not yet have been added to the
306 // incremental collection set (it gets added when it is
307 // retired as the current allocation region).
308 if (_curr->in_collection_set()) {
309 // Update the collection set policy information for this region
310 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
311 }
313 _curr = _curr->get_next_young_region();
314 if (_curr == NULL) {
315 _last_sampled_rs_lengths = _sampled_rs_lengths;
316 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
317 }
318 }
320 void
321 YoungList::reset_auxilary_lists() {
322 guarantee( is_empty(), "young list should be empty" );
323 assert(check_list_well_formed(), "young list should be well formed");
325 // Add survivor regions to SurvRateGroup.
326 _g1h->g1_policy()->note_start_adding_survivor_regions();
327 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
329 int young_index_in_cset = 0;
330 for (HeapRegion* curr = _survivor_head;
331 curr != NULL;
332 curr = curr->get_next_young_region()) {
333 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
335 // The region is a non-empty survivor so let's add it to
336 // the incremental collection set for the next evacuation
337 // pause.
338 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
339 young_index_in_cset += 1;
340 }
341 assert((size_t) young_index_in_cset == _survivor_length,
342 "post-condition");
343 _g1h->g1_policy()->note_stop_adding_survivor_regions();
345 _head = _survivor_head;
346 _length = _survivor_length;
347 if (_survivor_head != NULL) {
348 assert(_survivor_tail != NULL, "cause it shouldn't be");
349 assert(_survivor_length > 0, "invariant");
350 _survivor_tail->set_next_young_region(NULL);
351 }
353 // Don't clear the survivor list handles until the start of
354 // the next evacuation pause - we need it in order to re-tag
355 // the survivor regions from this evacuation pause as 'young'
356 // at the start of the next.
358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
360 assert(check_list_well_formed(), "young list should be well formed");
361 }
363 void YoungList::print() {
364 HeapRegion* lists[] = {_head, _survivor_head};
365 const char* names[] = {"YOUNG", "SURVIVOR"};
367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
369 HeapRegion *curr = lists[list];
370 if (curr == NULL)
371 gclog_or_tty->print_cr(" empty");
372 while (curr != NULL) {
373 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
374 "age: %4d, y: %d, surv: %d",
375 curr->bottom(), curr->end(),
376 curr->top(),
377 curr->prev_top_at_mark_start(),
378 curr->next_top_at_mark_start(),
379 curr->top_at_conc_mark_count(),
380 curr->age_in_surv_rate_group_cond(),
381 curr->is_young(),
382 curr->is_survivor());
383 curr = curr->get_next_young_region();
384 }
385 }
387 gclog_or_tty->print_cr("");
388 }
390 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
391 {
392 // Claim the right to put the region on the dirty cards region list
393 // by installing a self pointer.
394 HeapRegion* next = hr->get_next_dirty_cards_region();
395 if (next == NULL) {
396 HeapRegion* res = (HeapRegion*)
397 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
398 NULL);
399 if (res == NULL) {
400 HeapRegion* head;
401 do {
402 // Put the region to the dirty cards region list.
403 head = _dirty_cards_region_list;
404 next = (HeapRegion*)
405 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
406 if (next == head) {
407 assert(hr->get_next_dirty_cards_region() == hr,
408 "hr->get_next_dirty_cards_region() != hr");
409 if (next == NULL) {
410 // The last region in the list points to itself.
411 hr->set_next_dirty_cards_region(hr);
412 } else {
413 hr->set_next_dirty_cards_region(next);
414 }
415 }
416 } while (next != head);
417 }
418 }
419 }
421 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
422 {
423 HeapRegion* head;
424 HeapRegion* hr;
425 do {
426 head = _dirty_cards_region_list;
427 if (head == NULL) {
428 return NULL;
429 }
430 HeapRegion* new_head = head->get_next_dirty_cards_region();
431 if (head == new_head) {
432 // The last region.
433 new_head = NULL;
434 }
435 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
436 head);
437 } while (hr != head);
438 assert(hr != NULL, "invariant");
439 hr->set_next_dirty_cards_region(NULL);
440 return hr;
441 }
443 void G1CollectedHeap::stop_conc_gc_threads() {
444 _cg1r->stop();
445 _cmThread->stop();
446 }
448 #ifdef ASSERT
449 // A region is added to the collection set as it is retired
450 // so an address p can point to a region which will be in the
451 // collection set but has not yet been retired. This method
452 // therefore is only accurate during a GC pause after all
453 // regions have been retired. It is used for debugging
454 // to check if an nmethod has references to objects that can
455 // be move during a partial collection. Though it can be
456 // inaccurate, it is sufficient for G1 because the conservative
457 // implementation of is_scavengable() for G1 will indicate that
458 // all nmethods must be scanned during a partial collection.
459 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
460 HeapRegion* hr = heap_region_containing(p);
461 return hr != NULL && hr->in_collection_set();
462 }
463 #endif
465 // Returns true if the reference points to an object that
466 // can move in an incremental collecction.
467 bool G1CollectedHeap::is_scavengable(const void* p) {
468 G1CollectedHeap* g1h = G1CollectedHeap::heap();
469 G1CollectorPolicy* g1p = g1h->g1_policy();
470 HeapRegion* hr = heap_region_containing(p);
471 if (hr == NULL) {
472 // perm gen (or null)
473 return false;
474 } else {
475 return !hr->isHumongous();
476 }
477 }
479 void G1CollectedHeap::check_ct_logs_at_safepoint() {
480 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
481 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
483 // Count the dirty cards at the start.
484 CountNonCleanMemRegionClosure count1(this);
485 ct_bs->mod_card_iterate(&count1);
486 int orig_count = count1.n();
488 // First clear the logged cards.
489 ClearLoggedCardTableEntryClosure clear;
490 dcqs.set_closure(&clear);
491 dcqs.apply_closure_to_all_completed_buffers();
492 dcqs.iterate_closure_all_threads(false);
493 clear.print_histo();
495 // Now ensure that there's no dirty cards.
496 CountNonCleanMemRegionClosure count2(this);
497 ct_bs->mod_card_iterate(&count2);
498 if (count2.n() != 0) {
499 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
500 count2.n(), orig_count);
501 }
502 guarantee(count2.n() == 0, "Card table should be clean.");
504 RedirtyLoggedCardTableEntryClosure redirty;
505 JavaThread::dirty_card_queue_set().set_closure(&redirty);
506 dcqs.apply_closure_to_all_completed_buffers();
507 dcqs.iterate_closure_all_threads(false);
508 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
509 clear.calls(), orig_count);
510 guarantee(redirty.calls() == clear.calls(),
511 "Or else mechanism is broken.");
513 CountNonCleanMemRegionClosure count3(this);
514 ct_bs->mod_card_iterate(&count3);
515 if (count3.n() != orig_count) {
516 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
517 orig_count, count3.n());
518 guarantee(count3.n() >= orig_count, "Should have restored them all.");
519 }
521 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
522 }
524 // Private class members.
526 G1CollectedHeap* G1CollectedHeap::_g1h;
528 // Private methods.
530 HeapRegion*
531 G1CollectedHeap::new_region_try_secondary_free_list() {
532 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
533 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
534 if (!_secondary_free_list.is_empty()) {
535 if (G1ConcRegionFreeingVerbose) {
536 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
537 "secondary_free_list has "SIZE_FORMAT" entries",
538 _secondary_free_list.length());
539 }
540 // It looks as if there are free regions available on the
541 // secondary_free_list. Let's move them to the free_list and try
542 // again to allocate from it.
543 append_secondary_free_list();
545 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
546 "empty we should have moved at least one entry to the free_list");
547 HeapRegion* res = _free_list.remove_head();
548 if (G1ConcRegionFreeingVerbose) {
549 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
550 "allocated "HR_FORMAT" from secondary_free_list",
551 HR_FORMAT_PARAMS(res));
552 }
553 return res;
554 }
556 // Wait here until we get notifed either when (a) there are no
557 // more free regions coming or (b) some regions have been moved on
558 // the secondary_free_list.
559 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
560 }
562 if (G1ConcRegionFreeingVerbose) {
563 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
564 "could not allocate from secondary_free_list");
565 }
566 return NULL;
567 }
569 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
570 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
571 "the only time we use this to allocate a humongous region is "
572 "when we are allocating a single humongous region");
574 HeapRegion* res;
575 if (G1StressConcRegionFreeing) {
576 if (!_secondary_free_list.is_empty()) {
577 if (G1ConcRegionFreeingVerbose) {
578 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
579 "forced to look at the secondary_free_list");
580 }
581 res = new_region_try_secondary_free_list();
582 if (res != NULL) {
583 return res;
584 }
585 }
586 }
587 res = _free_list.remove_head_or_null();
588 if (res == NULL) {
589 if (G1ConcRegionFreeingVerbose) {
590 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
591 "res == NULL, trying the secondary_free_list");
592 }
593 res = new_region_try_secondary_free_list();
594 }
595 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
596 // Currently, only attempts to allocate GC alloc regions set
597 // do_expand to true. So, we should only reach here during a
598 // safepoint. If this assumption changes we might have to
599 // reconsider the use of _expand_heap_after_alloc_failure.
600 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
602 ergo_verbose1(ErgoHeapSizing,
603 "attempt heap expansion",
604 ergo_format_reason("region allocation request failed")
605 ergo_format_byte("allocation request"),
606 word_size * HeapWordSize);
607 if (expand(word_size * HeapWordSize)) {
608 // Given that expand() succeeded in expanding the heap, and we
609 // always expand the heap by an amount aligned to the heap
610 // region size, the free list should in theory not be empty. So
611 // it would probably be OK to use remove_head(). But the extra
612 // check for NULL is unlikely to be a performance issue here (we
613 // just expanded the heap!) so let's just be conservative and
614 // use remove_head_or_null().
615 res = _free_list.remove_head_or_null();
616 } else {
617 _expand_heap_after_alloc_failure = false;
618 }
619 }
620 return res;
621 }
623 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
624 size_t word_size) {
625 assert(isHumongous(word_size), "word_size should be humongous");
626 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
628 size_t first = G1_NULL_HRS_INDEX;
629 if (num_regions == 1) {
630 // Only one region to allocate, no need to go through the slower
631 // path. The caller will attempt the expasion if this fails, so
632 // let's not try to expand here too.
633 HeapRegion* hr = new_region(word_size, false /* do_expand */);
634 if (hr != NULL) {
635 first = hr->hrs_index();
636 } else {
637 first = G1_NULL_HRS_INDEX;
638 }
639 } else {
640 // We can't allocate humongous regions while cleanupComplete() is
641 // running, since some of the regions we find to be empty might not
642 // yet be added to the free list and it is not straightforward to
643 // know which list they are on so that we can remove them. Note
644 // that we only need to do this if we need to allocate more than
645 // one region to satisfy the current humongous allocation
646 // request. If we are only allocating one region we use the common
647 // region allocation code (see above).
648 wait_while_free_regions_coming();
649 append_secondary_free_list_if_not_empty_with_lock();
651 if (free_regions() >= num_regions) {
652 first = _hrs.find_contiguous(num_regions);
653 if (first != G1_NULL_HRS_INDEX) {
654 for (size_t i = first; i < first + num_regions; ++i) {
655 HeapRegion* hr = region_at(i);
656 assert(hr->is_empty(), "sanity");
657 assert(is_on_master_free_list(hr), "sanity");
658 hr->set_pending_removal(true);
659 }
660 _free_list.remove_all_pending(num_regions);
661 }
662 }
663 }
664 return first;
665 }
667 HeapWord*
668 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first,
669 size_t num_regions,
670 size_t word_size) {
671 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
672 assert(isHumongous(word_size), "word_size should be humongous");
673 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
675 // Index of last region in the series + 1.
676 size_t last = first + num_regions;
678 // We need to initialize the region(s) we just discovered. This is
679 // a bit tricky given that it can happen concurrently with
680 // refinement threads refining cards on these regions and
681 // potentially wanting to refine the BOT as they are scanning
682 // those cards (this can happen shortly after a cleanup; see CR
683 // 6991377). So we have to set up the region(s) carefully and in
684 // a specific order.
686 // The word size sum of all the regions we will allocate.
687 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
688 assert(word_size <= word_size_sum, "sanity");
690 // This will be the "starts humongous" region.
691 HeapRegion* first_hr = region_at(first);
692 // The header of the new object will be placed at the bottom of
693 // the first region.
694 HeapWord* new_obj = first_hr->bottom();
695 // This will be the new end of the first region in the series that
696 // should also match the end of the last region in the seriers.
697 HeapWord* new_end = new_obj + word_size_sum;
698 // This will be the new top of the first region that will reflect
699 // this allocation.
700 HeapWord* new_top = new_obj + word_size;
702 // First, we need to zero the header of the space that we will be
703 // allocating. When we update top further down, some refinement
704 // threads might try to scan the region. By zeroing the header we
705 // ensure that any thread that will try to scan the region will
706 // come across the zero klass word and bail out.
707 //
708 // NOTE: It would not have been correct to have used
709 // CollectedHeap::fill_with_object() and make the space look like
710 // an int array. The thread that is doing the allocation will
711 // later update the object header to a potentially different array
712 // type and, for a very short period of time, the klass and length
713 // fields will be inconsistent. This could cause a refinement
714 // thread to calculate the object size incorrectly.
715 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
717 // We will set up the first region as "starts humongous". This
718 // will also update the BOT covering all the regions to reflect
719 // that there is a single object that starts at the bottom of the
720 // first region.
721 first_hr->set_startsHumongous(new_top, new_end);
723 // Then, if there are any, we will set up the "continues
724 // humongous" regions.
725 HeapRegion* hr = NULL;
726 for (size_t i = first + 1; i < last; ++i) {
727 hr = region_at(i);
728 hr->set_continuesHumongous(first_hr);
729 }
730 // If we have "continues humongous" regions (hr != NULL), then the
731 // end of the last one should match new_end.
732 assert(hr == NULL || hr->end() == new_end, "sanity");
734 // Up to this point no concurrent thread would have been able to
735 // do any scanning on any region in this series. All the top
736 // fields still point to bottom, so the intersection between
737 // [bottom,top] and [card_start,card_end] will be empty. Before we
738 // update the top fields, we'll do a storestore to make sure that
739 // no thread sees the update to top before the zeroing of the
740 // object header and the BOT initialization.
741 OrderAccess::storestore();
743 // Now that the BOT and the object header have been initialized,
744 // we can update top of the "starts humongous" region.
745 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
746 "new_top should be in this region");
747 first_hr->set_top(new_top);
748 if (_hr_printer.is_active()) {
749 HeapWord* bottom = first_hr->bottom();
750 HeapWord* end = first_hr->orig_end();
751 if ((first + 1) == last) {
752 // the series has a single humongous region
753 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
754 } else {
755 // the series has more than one humongous regions
756 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
757 }
758 }
760 // Now, we will update the top fields of the "continues humongous"
761 // regions. The reason we need to do this is that, otherwise,
762 // these regions would look empty and this will confuse parts of
763 // G1. For example, the code that looks for a consecutive number
764 // of empty regions will consider them empty and try to
765 // re-allocate them. We can extend is_empty() to also include
766 // !continuesHumongous(), but it is easier to just update the top
767 // fields here. The way we set top for all regions (i.e., top ==
768 // end for all regions but the last one, top == new_top for the
769 // last one) is actually used when we will free up the humongous
770 // region in free_humongous_region().
771 hr = NULL;
772 for (size_t i = first + 1; i < last; ++i) {
773 hr = region_at(i);
774 if ((i + 1) == last) {
775 // last continues humongous region
776 assert(hr->bottom() < new_top && new_top <= hr->end(),
777 "new_top should fall on this region");
778 hr->set_top(new_top);
779 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
780 } else {
781 // not last one
782 assert(new_top > hr->end(), "new_top should be above this region");
783 hr->set_top(hr->end());
784 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
785 }
786 }
787 // If we have continues humongous regions (hr != NULL), then the
788 // end of the last one should match new_end and its top should
789 // match new_top.
790 assert(hr == NULL ||
791 (hr->end() == new_end && hr->top() == new_top), "sanity");
793 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
794 _summary_bytes_used += first_hr->used();
795 _humongous_set.add(first_hr);
797 return new_obj;
798 }
800 // If could fit into free regions w/o expansion, try.
801 // Otherwise, if can expand, do so.
802 // Otherwise, if using ex regions might help, try with ex given back.
803 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
804 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
806 verify_region_sets_optional();
808 size_t num_regions =
809 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
810 size_t x_size = expansion_regions();
811 size_t fs = _hrs.free_suffix();
812 size_t first = humongous_obj_allocate_find_first(num_regions, word_size);
813 if (first == G1_NULL_HRS_INDEX) {
814 // The only thing we can do now is attempt expansion.
815 if (fs + x_size >= num_regions) {
816 // If the number of regions we're trying to allocate for this
817 // object is at most the number of regions in the free suffix,
818 // then the call to humongous_obj_allocate_find_first() above
819 // should have succeeded and we wouldn't be here.
820 //
821 // We should only be trying to expand when the free suffix is
822 // not sufficient for the object _and_ we have some expansion
823 // room available.
824 assert(num_regions > fs, "earlier allocation should have succeeded");
826 ergo_verbose1(ErgoHeapSizing,
827 "attempt heap expansion",
828 ergo_format_reason("humongous allocation request failed")
829 ergo_format_byte("allocation request"),
830 word_size * HeapWordSize);
831 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
832 // Even though the heap was expanded, it might not have
833 // reached the desired size. So, we cannot assume that the
834 // allocation will succeed.
835 first = humongous_obj_allocate_find_first(num_regions, word_size);
836 }
837 }
838 }
840 HeapWord* result = NULL;
841 if (first != G1_NULL_HRS_INDEX) {
842 result =
843 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
844 assert(result != NULL, "it should always return a valid result");
846 // A successful humongous object allocation changes the used space
847 // information of the old generation so we need to recalculate the
848 // sizes and update the jstat counters here.
849 g1mm()->update_sizes();
850 }
852 verify_region_sets_optional();
854 return result;
855 }
857 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
858 assert_heap_not_locked_and_not_at_safepoint();
859 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
861 unsigned int dummy_gc_count_before;
862 return attempt_allocation(word_size, &dummy_gc_count_before);
863 }
865 HeapWord*
866 G1CollectedHeap::mem_allocate(size_t word_size,
867 bool* gc_overhead_limit_was_exceeded) {
868 assert_heap_not_locked_and_not_at_safepoint();
870 // Loop until the allocation is satisified, or unsatisfied after GC.
871 for (int try_count = 1; /* we'll return */; try_count += 1) {
872 unsigned int gc_count_before;
874 HeapWord* result = NULL;
875 if (!isHumongous(word_size)) {
876 result = attempt_allocation(word_size, &gc_count_before);
877 } else {
878 result = attempt_allocation_humongous(word_size, &gc_count_before);
879 }
880 if (result != NULL) {
881 return result;
882 }
884 // Create the garbage collection operation...
885 VM_G1CollectForAllocation op(gc_count_before, word_size);
886 // ...and get the VM thread to execute it.
887 VMThread::execute(&op);
889 if (op.prologue_succeeded() && op.pause_succeeded()) {
890 // If the operation was successful we'll return the result even
891 // if it is NULL. If the allocation attempt failed immediately
892 // after a Full GC, it's unlikely we'll be able to allocate now.
893 HeapWord* result = op.result();
894 if (result != NULL && !isHumongous(word_size)) {
895 // Allocations that take place on VM operations do not do any
896 // card dirtying and we have to do it here. We only have to do
897 // this for non-humongous allocations, though.
898 dirty_young_block(result, word_size);
899 }
900 return result;
901 } else {
902 assert(op.result() == NULL,
903 "the result should be NULL if the VM op did not succeed");
904 }
906 // Give a warning if we seem to be looping forever.
907 if ((QueuedAllocationWarningCount > 0) &&
908 (try_count % QueuedAllocationWarningCount == 0)) {
909 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
910 }
911 }
913 ShouldNotReachHere();
914 return NULL;
915 }
917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
918 unsigned int *gc_count_before_ret) {
919 // Make sure you read the note in attempt_allocation_humongous().
921 assert_heap_not_locked_and_not_at_safepoint();
922 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
923 "be called for humongous allocation requests");
925 // We should only get here after the first-level allocation attempt
926 // (attempt_allocation()) failed to allocate.
928 // We will loop until a) we manage to successfully perform the
929 // allocation or b) we successfully schedule a collection which
930 // fails to perform the allocation. b) is the only case when we'll
931 // return NULL.
932 HeapWord* result = NULL;
933 for (int try_count = 1; /* we'll return */; try_count += 1) {
934 bool should_try_gc;
935 unsigned int gc_count_before;
937 {
938 MutexLockerEx x(Heap_lock);
940 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
941 false /* bot_updates */);
942 if (result != NULL) {
943 return result;
944 }
946 // If we reach here, attempt_allocation_locked() above failed to
947 // allocate a new region. So the mutator alloc region should be NULL.
948 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
950 if (GC_locker::is_active_and_needs_gc()) {
951 if (g1_policy()->can_expand_young_list()) {
952 // No need for an ergo verbose message here,
953 // can_expand_young_list() does this when it returns true.
954 result = _mutator_alloc_region.attempt_allocation_force(word_size,
955 false /* bot_updates */);
956 if (result != NULL) {
957 return result;
958 }
959 }
960 should_try_gc = false;
961 } else {
962 // Read the GC count while still holding the Heap_lock.
963 gc_count_before = SharedHeap::heap()->total_collections();
964 should_try_gc = true;
965 }
966 }
968 if (should_try_gc) {
969 bool succeeded;
970 result = do_collection_pause(word_size, gc_count_before, &succeeded);
971 if (result != NULL) {
972 assert(succeeded, "only way to get back a non-NULL result");
973 return result;
974 }
976 if (succeeded) {
977 // If we get here we successfully scheduled a collection which
978 // failed to allocate. No point in trying to allocate
979 // further. We'll just return NULL.
980 MutexLockerEx x(Heap_lock);
981 *gc_count_before_ret = SharedHeap::heap()->total_collections();
982 return NULL;
983 }
984 } else {
985 GC_locker::stall_until_clear();
986 }
988 // We can reach here if we were unsuccessul in scheduling a
989 // collection (because another thread beat us to it) or if we were
990 // stalled due to the GC locker. In either can we should retry the
991 // allocation attempt in case another thread successfully
992 // performed a collection and reclaimed enough space. We do the
993 // first attempt (without holding the Heap_lock) here and the
994 // follow-on attempt will be at the start of the next loop
995 // iteration (after taking the Heap_lock).
996 result = _mutator_alloc_region.attempt_allocation(word_size,
997 false /* bot_updates */);
998 if (result != NULL ){
999 return result;
1000 }
1002 // Give a warning if we seem to be looping forever.
1003 if ((QueuedAllocationWarningCount > 0) &&
1004 (try_count % QueuedAllocationWarningCount == 0)) {
1005 warning("G1CollectedHeap::attempt_allocation_slow() "
1006 "retries %d times", try_count);
1007 }
1008 }
1010 ShouldNotReachHere();
1011 return NULL;
1012 }
1014 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1015 unsigned int * gc_count_before_ret) {
1016 // The structure of this method has a lot of similarities to
1017 // attempt_allocation_slow(). The reason these two were not merged
1018 // into a single one is that such a method would require several "if
1019 // allocation is not humongous do this, otherwise do that"
1020 // conditional paths which would obscure its flow. In fact, an early
1021 // version of this code did use a unified method which was harder to
1022 // follow and, as a result, it had subtle bugs that were hard to
1023 // track down. So keeping these two methods separate allows each to
1024 // be more readable. It will be good to keep these two in sync as
1025 // much as possible.
1027 assert_heap_not_locked_and_not_at_safepoint();
1028 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1029 "should only be called for humongous allocations");
1031 // We will loop until a) we manage to successfully perform the
1032 // allocation or b) we successfully schedule a collection which
1033 // fails to perform the allocation. b) is the only case when we'll
1034 // return NULL.
1035 HeapWord* result = NULL;
1036 for (int try_count = 1; /* we'll return */; try_count += 1) {
1037 bool should_try_gc;
1038 unsigned int gc_count_before;
1040 {
1041 MutexLockerEx x(Heap_lock);
1043 // Given that humongous objects are not allocated in young
1044 // regions, we'll first try to do the allocation without doing a
1045 // collection hoping that there's enough space in the heap.
1046 result = humongous_obj_allocate(word_size);
1047 if (result != NULL) {
1048 return result;
1049 }
1051 if (GC_locker::is_active_and_needs_gc()) {
1052 should_try_gc = false;
1053 } else {
1054 // Read the GC count while still holding the Heap_lock.
1055 gc_count_before = SharedHeap::heap()->total_collections();
1056 should_try_gc = true;
1057 }
1058 }
1060 if (should_try_gc) {
1061 // If we failed to allocate the humongous object, we should try to
1062 // do a collection pause (if we're allowed) in case it reclaims
1063 // enough space for the allocation to succeed after the pause.
1065 bool succeeded;
1066 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1067 if (result != NULL) {
1068 assert(succeeded, "only way to get back a non-NULL result");
1069 return result;
1070 }
1072 if (succeeded) {
1073 // If we get here we successfully scheduled a collection which
1074 // failed to allocate. No point in trying to allocate
1075 // further. We'll just return NULL.
1076 MutexLockerEx x(Heap_lock);
1077 *gc_count_before_ret = SharedHeap::heap()->total_collections();
1078 return NULL;
1079 }
1080 } else {
1081 GC_locker::stall_until_clear();
1082 }
1084 // We can reach here if we were unsuccessul in scheduling a
1085 // collection (because another thread beat us to it) or if we were
1086 // stalled due to the GC locker. In either can we should retry the
1087 // allocation attempt in case another thread successfully
1088 // performed a collection and reclaimed enough space. Give a
1089 // warning if we seem to be looping forever.
1091 if ((QueuedAllocationWarningCount > 0) &&
1092 (try_count % QueuedAllocationWarningCount == 0)) {
1093 warning("G1CollectedHeap::attempt_allocation_humongous() "
1094 "retries %d times", try_count);
1095 }
1096 }
1098 ShouldNotReachHere();
1099 return NULL;
1100 }
1102 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1103 bool expect_null_mutator_alloc_region) {
1104 assert_at_safepoint(true /* should_be_vm_thread */);
1105 assert(_mutator_alloc_region.get() == NULL ||
1106 !expect_null_mutator_alloc_region,
1107 "the current alloc region was unexpectedly found to be non-NULL");
1109 if (!isHumongous(word_size)) {
1110 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1111 false /* bot_updates */);
1112 } else {
1113 return humongous_obj_allocate(word_size);
1114 }
1116 ShouldNotReachHere();
1117 }
1119 class PostMCRemSetClearClosure: public HeapRegionClosure {
1120 ModRefBarrierSet* _mr_bs;
1121 public:
1122 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1123 bool doHeapRegion(HeapRegion* r) {
1124 r->reset_gc_time_stamp();
1125 if (r->continuesHumongous())
1126 return false;
1127 HeapRegionRemSet* hrrs = r->rem_set();
1128 if (hrrs != NULL) hrrs->clear();
1129 // You might think here that we could clear just the cards
1130 // corresponding to the used region. But no: if we leave a dirty card
1131 // in a region we might allocate into, then it would prevent that card
1132 // from being enqueued, and cause it to be missed.
1133 // Re: the performance cost: we shouldn't be doing full GC anyway!
1134 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1135 return false;
1136 }
1137 };
1140 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1141 ModRefBarrierSet* _mr_bs;
1142 public:
1143 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1144 bool doHeapRegion(HeapRegion* r) {
1145 if (r->continuesHumongous()) return false;
1146 if (r->used_region().word_size() != 0) {
1147 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1148 }
1149 return false;
1150 }
1151 };
1153 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1154 G1CollectedHeap* _g1h;
1155 UpdateRSOopClosure _cl;
1156 int _worker_i;
1157 public:
1158 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1159 _cl(g1->g1_rem_set(), worker_i),
1160 _worker_i(worker_i),
1161 _g1h(g1)
1162 { }
1164 bool doHeapRegion(HeapRegion* r) {
1165 if (!r->continuesHumongous()) {
1166 _cl.set_from(r);
1167 r->oop_iterate(&_cl);
1168 }
1169 return false;
1170 }
1171 };
1173 class ParRebuildRSTask: public AbstractGangTask {
1174 G1CollectedHeap* _g1;
1175 public:
1176 ParRebuildRSTask(G1CollectedHeap* g1)
1177 : AbstractGangTask("ParRebuildRSTask"),
1178 _g1(g1)
1179 { }
1181 void work(uint worker_id) {
1182 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1183 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1184 _g1->workers()->active_workers(),
1185 HeapRegion::RebuildRSClaimValue);
1186 }
1187 };
1189 class PostCompactionPrinterClosure: public HeapRegionClosure {
1190 private:
1191 G1HRPrinter* _hr_printer;
1192 public:
1193 bool doHeapRegion(HeapRegion* hr) {
1194 assert(!hr->is_young(), "not expecting to find young regions");
1195 // We only generate output for non-empty regions.
1196 if (!hr->is_empty()) {
1197 if (!hr->isHumongous()) {
1198 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1199 } else if (hr->startsHumongous()) {
1200 if (hr->capacity() == HeapRegion::GrainBytes) {
1201 // single humongous region
1202 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1203 } else {
1204 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1205 }
1206 } else {
1207 assert(hr->continuesHumongous(), "only way to get here");
1208 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1209 }
1210 }
1211 return false;
1212 }
1214 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1215 : _hr_printer(hr_printer) { }
1216 };
1218 bool G1CollectedHeap::do_collection(bool explicit_gc,
1219 bool clear_all_soft_refs,
1220 size_t word_size) {
1221 assert_at_safepoint(true /* should_be_vm_thread */);
1223 if (GC_locker::check_active_before_gc()) {
1224 return false;
1225 }
1227 SvcGCMarker sgcm(SvcGCMarker::FULL);
1228 ResourceMark rm;
1230 if (PrintHeapAtGC) {
1231 Universe::print_heap_before_gc();
1232 }
1234 HRSPhaseSetter x(HRSPhaseFullGC);
1235 verify_region_sets_optional();
1237 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1238 collector_policy()->should_clear_all_soft_refs();
1240 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1242 {
1243 IsGCActiveMark x;
1245 // Timing
1246 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1247 assert(!system_gc || explicit_gc, "invariant");
1248 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1249 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1250 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1251 PrintGC, true, gclog_or_tty);
1253 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1254 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1256 double start = os::elapsedTime();
1257 g1_policy()->record_full_collection_start();
1259 wait_while_free_regions_coming();
1260 append_secondary_free_list_if_not_empty_with_lock();
1262 gc_prologue(true);
1263 increment_total_collections(true /* full gc */);
1265 size_t g1h_prev_used = used();
1266 assert(used() == recalculate_used(), "Should be equal");
1268 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1269 HandleMark hm; // Discard invalid handles created during verification
1270 gclog_or_tty->print(" VerifyBeforeGC:");
1271 prepare_for_verify();
1272 Universe::verify(/* allow dirty */ true,
1273 /* silent */ false,
1274 /* option */ VerifyOption_G1UsePrevMarking);
1276 }
1277 pre_full_gc_dump();
1279 COMPILER2_PRESENT(DerivedPointerTable::clear());
1281 // Disable discovery and empty the discovered lists
1282 // for the CM ref processor.
1283 ref_processor_cm()->disable_discovery();
1284 ref_processor_cm()->abandon_partial_discovery();
1285 ref_processor_cm()->verify_no_references_recorded();
1287 // Abandon current iterations of concurrent marking and concurrent
1288 // refinement, if any are in progress.
1289 concurrent_mark()->abort();
1291 // Make sure we'll choose a new allocation region afterwards.
1292 release_mutator_alloc_region();
1293 abandon_gc_alloc_regions();
1294 g1_rem_set()->cleanupHRRS();
1296 // We should call this after we retire any currently active alloc
1297 // regions so that all the ALLOC / RETIRE events are generated
1298 // before the start GC event.
1299 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1301 // We may have added regions to the current incremental collection
1302 // set between the last GC or pause and now. We need to clear the
1303 // incremental collection set and then start rebuilding it afresh
1304 // after this full GC.
1305 abandon_collection_set(g1_policy()->inc_cset_head());
1306 g1_policy()->clear_incremental_cset();
1307 g1_policy()->stop_incremental_cset_building();
1309 tear_down_region_sets(false /* free_list_only */);
1310 g1_policy()->set_gcs_are_young(true);
1312 // See the comments in g1CollectedHeap.hpp and
1313 // G1CollectedHeap::ref_processing_init() about
1314 // how reference processing currently works in G1.
1316 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1317 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1319 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1320 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1322 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1323 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1325 // Do collection work
1326 {
1327 HandleMark hm; // Discard invalid handles created during gc
1328 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1329 }
1331 assert(free_regions() == 0, "we should not have added any free regions");
1332 rebuild_region_sets(false /* free_list_only */);
1334 // Enqueue any discovered reference objects that have
1335 // not been removed from the discovered lists.
1336 ref_processor_stw()->enqueue_discovered_references();
1338 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1340 MemoryService::track_memory_usage();
1342 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1343 HandleMark hm; // Discard invalid handles created during verification
1344 gclog_or_tty->print(" VerifyAfterGC:");
1345 prepare_for_verify();
1346 Universe::verify(/* allow dirty */ false,
1347 /* silent */ false,
1348 /* option */ VerifyOption_G1UsePrevMarking);
1350 }
1352 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1353 ref_processor_stw()->verify_no_references_recorded();
1355 // Note: since we've just done a full GC, concurrent
1356 // marking is no longer active. Therefore we need not
1357 // re-enable reference discovery for the CM ref processor.
1358 // That will be done at the start of the next marking cycle.
1359 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1360 ref_processor_cm()->verify_no_references_recorded();
1362 reset_gc_time_stamp();
1363 // Since everything potentially moved, we will clear all remembered
1364 // sets, and clear all cards. Later we will rebuild remebered
1365 // sets. We will also reset the GC time stamps of the regions.
1366 PostMCRemSetClearClosure rs_clear(mr_bs());
1367 heap_region_iterate(&rs_clear);
1369 // Resize the heap if necessary.
1370 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1372 if (_hr_printer.is_active()) {
1373 // We should do this after we potentially resize the heap so
1374 // that all the COMMIT / UNCOMMIT events are generated before
1375 // the end GC event.
1377 PostCompactionPrinterClosure cl(hr_printer());
1378 heap_region_iterate(&cl);
1380 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1381 }
1383 if (_cg1r->use_cache()) {
1384 _cg1r->clear_and_record_card_counts();
1385 _cg1r->clear_hot_cache();
1386 }
1388 // Rebuild remembered sets of all regions.
1389 if (G1CollectedHeap::use_parallel_gc_threads()) {
1390 uint n_workers =
1391 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1392 workers()->active_workers(),
1393 Threads::number_of_non_daemon_threads());
1394 assert(UseDynamicNumberOfGCThreads ||
1395 n_workers == workers()->total_workers(),
1396 "If not dynamic should be using all the workers");
1397 workers()->set_active_workers(n_workers);
1398 // Set parallel threads in the heap (_n_par_threads) only
1399 // before a parallel phase and always reset it to 0 after
1400 // the phase so that the number of parallel threads does
1401 // no get carried forward to a serial phase where there
1402 // may be code that is "possibly_parallel".
1403 set_par_threads(n_workers);
1405 ParRebuildRSTask rebuild_rs_task(this);
1406 assert(check_heap_region_claim_values(
1407 HeapRegion::InitialClaimValue), "sanity check");
1408 assert(UseDynamicNumberOfGCThreads ||
1409 workers()->active_workers() == workers()->total_workers(),
1410 "Unless dynamic should use total workers");
1411 // Use the most recent number of active workers
1412 assert(workers()->active_workers() > 0,
1413 "Active workers not properly set");
1414 set_par_threads(workers()->active_workers());
1415 workers()->run_task(&rebuild_rs_task);
1416 set_par_threads(0);
1417 assert(check_heap_region_claim_values(
1418 HeapRegion::RebuildRSClaimValue), "sanity check");
1419 reset_heap_region_claim_values();
1420 } else {
1421 RebuildRSOutOfRegionClosure rebuild_rs(this);
1422 heap_region_iterate(&rebuild_rs);
1423 }
1425 if (PrintGC) {
1426 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1427 }
1429 if (true) { // FIXME
1430 // Ask the permanent generation to adjust size for full collections
1431 perm()->compute_new_size();
1432 }
1434 // Start a new incremental collection set for the next pause
1435 assert(g1_policy()->collection_set() == NULL, "must be");
1436 g1_policy()->start_incremental_cset_building();
1438 // Clear the _cset_fast_test bitmap in anticipation of adding
1439 // regions to the incremental collection set for the next
1440 // evacuation pause.
1441 clear_cset_fast_test();
1443 init_mutator_alloc_region();
1445 double end = os::elapsedTime();
1446 g1_policy()->record_full_collection_end();
1448 #ifdef TRACESPINNING
1449 ParallelTaskTerminator::print_termination_counts();
1450 #endif
1452 gc_epilogue(true);
1454 // Discard all rset updates
1455 JavaThread::dirty_card_queue_set().abandon_logs();
1456 assert(!G1DeferredRSUpdate
1457 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1458 }
1460 _young_list->reset_sampled_info();
1461 // At this point there should be no regions in the
1462 // entire heap tagged as young.
1463 assert( check_young_list_empty(true /* check_heap */),
1464 "young list should be empty at this point");
1466 // Update the number of full collections that have been completed.
1467 increment_full_collections_completed(false /* concurrent */);
1469 _hrs.verify_optional();
1470 verify_region_sets_optional();
1472 if (PrintHeapAtGC) {
1473 Universe::print_heap_after_gc();
1474 }
1475 g1mm()->update_sizes();
1476 post_full_gc_dump();
1478 return true;
1479 }
1481 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1482 // do_collection() will return whether it succeeded in performing
1483 // the GC. Currently, there is no facility on the
1484 // do_full_collection() API to notify the caller than the collection
1485 // did not succeed (e.g., because it was locked out by the GC
1486 // locker). So, right now, we'll ignore the return value.
1487 bool dummy = do_collection(true, /* explicit_gc */
1488 clear_all_soft_refs,
1489 0 /* word_size */);
1490 }
1492 // This code is mostly copied from TenuredGeneration.
1493 void
1494 G1CollectedHeap::
1495 resize_if_necessary_after_full_collection(size_t word_size) {
1496 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1498 // Include the current allocation, if any, and bytes that will be
1499 // pre-allocated to support collections, as "used".
1500 const size_t used_after_gc = used();
1501 const size_t capacity_after_gc = capacity();
1502 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1504 // This is enforced in arguments.cpp.
1505 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1506 "otherwise the code below doesn't make sense");
1508 // We don't have floating point command-line arguments
1509 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1510 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1511 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1512 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1514 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1515 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1517 // We have to be careful here as these two calculations can overflow
1518 // 32-bit size_t's.
1519 double used_after_gc_d = (double) used_after_gc;
1520 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1521 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1523 // Let's make sure that they are both under the max heap size, which
1524 // by default will make them fit into a size_t.
1525 double desired_capacity_upper_bound = (double) max_heap_size;
1526 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1527 desired_capacity_upper_bound);
1528 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1529 desired_capacity_upper_bound);
1531 // We can now safely turn them into size_t's.
1532 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1533 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1535 // This assert only makes sense here, before we adjust them
1536 // with respect to the min and max heap size.
1537 assert(minimum_desired_capacity <= maximum_desired_capacity,
1538 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1539 "maximum_desired_capacity = "SIZE_FORMAT,
1540 minimum_desired_capacity, maximum_desired_capacity));
1542 // Should not be greater than the heap max size. No need to adjust
1543 // it with respect to the heap min size as it's a lower bound (i.e.,
1544 // we'll try to make the capacity larger than it, not smaller).
1545 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1546 // Should not be less than the heap min size. No need to adjust it
1547 // with respect to the heap max size as it's an upper bound (i.e.,
1548 // we'll try to make the capacity smaller than it, not greater).
1549 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1551 if (capacity_after_gc < minimum_desired_capacity) {
1552 // Don't expand unless it's significant
1553 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1554 ergo_verbose4(ErgoHeapSizing,
1555 "attempt heap expansion",
1556 ergo_format_reason("capacity lower than "
1557 "min desired capacity after Full GC")
1558 ergo_format_byte("capacity")
1559 ergo_format_byte("occupancy")
1560 ergo_format_byte_perc("min desired capacity"),
1561 capacity_after_gc, used_after_gc,
1562 minimum_desired_capacity, (double) MinHeapFreeRatio);
1563 expand(expand_bytes);
1565 // No expansion, now see if we want to shrink
1566 } else if (capacity_after_gc > maximum_desired_capacity) {
1567 // Capacity too large, compute shrinking size
1568 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1569 ergo_verbose4(ErgoHeapSizing,
1570 "attempt heap shrinking",
1571 ergo_format_reason("capacity higher than "
1572 "max desired capacity after Full GC")
1573 ergo_format_byte("capacity")
1574 ergo_format_byte("occupancy")
1575 ergo_format_byte_perc("max desired capacity"),
1576 capacity_after_gc, used_after_gc,
1577 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1578 shrink(shrink_bytes);
1579 }
1580 }
1583 HeapWord*
1584 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1585 bool* succeeded) {
1586 assert_at_safepoint(true /* should_be_vm_thread */);
1588 *succeeded = true;
1589 // Let's attempt the allocation first.
1590 HeapWord* result =
1591 attempt_allocation_at_safepoint(word_size,
1592 false /* expect_null_mutator_alloc_region */);
1593 if (result != NULL) {
1594 assert(*succeeded, "sanity");
1595 return result;
1596 }
1598 // In a G1 heap, we're supposed to keep allocation from failing by
1599 // incremental pauses. Therefore, at least for now, we'll favor
1600 // expansion over collection. (This might change in the future if we can
1601 // do something smarter than full collection to satisfy a failed alloc.)
1602 result = expand_and_allocate(word_size);
1603 if (result != NULL) {
1604 assert(*succeeded, "sanity");
1605 return result;
1606 }
1608 // Expansion didn't work, we'll try to do a Full GC.
1609 bool gc_succeeded = do_collection(false, /* explicit_gc */
1610 false, /* clear_all_soft_refs */
1611 word_size);
1612 if (!gc_succeeded) {
1613 *succeeded = false;
1614 return NULL;
1615 }
1617 // Retry the allocation
1618 result = attempt_allocation_at_safepoint(word_size,
1619 true /* expect_null_mutator_alloc_region */);
1620 if (result != NULL) {
1621 assert(*succeeded, "sanity");
1622 return result;
1623 }
1625 // Then, try a Full GC that will collect all soft references.
1626 gc_succeeded = do_collection(false, /* explicit_gc */
1627 true, /* clear_all_soft_refs */
1628 word_size);
1629 if (!gc_succeeded) {
1630 *succeeded = false;
1631 return NULL;
1632 }
1634 // Retry the allocation once more
1635 result = attempt_allocation_at_safepoint(word_size,
1636 true /* expect_null_mutator_alloc_region */);
1637 if (result != NULL) {
1638 assert(*succeeded, "sanity");
1639 return result;
1640 }
1642 assert(!collector_policy()->should_clear_all_soft_refs(),
1643 "Flag should have been handled and cleared prior to this point");
1645 // What else? We might try synchronous finalization later. If the total
1646 // space available is large enough for the allocation, then a more
1647 // complete compaction phase than we've tried so far might be
1648 // appropriate.
1649 assert(*succeeded, "sanity");
1650 return NULL;
1651 }
1653 // Attempting to expand the heap sufficiently
1654 // to support an allocation of the given "word_size". If
1655 // successful, perform the allocation and return the address of the
1656 // allocated block, or else "NULL".
1658 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1659 assert_at_safepoint(true /* should_be_vm_thread */);
1661 verify_region_sets_optional();
1663 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1664 ergo_verbose1(ErgoHeapSizing,
1665 "attempt heap expansion",
1666 ergo_format_reason("allocation request failed")
1667 ergo_format_byte("allocation request"),
1668 word_size * HeapWordSize);
1669 if (expand(expand_bytes)) {
1670 _hrs.verify_optional();
1671 verify_region_sets_optional();
1672 return attempt_allocation_at_safepoint(word_size,
1673 false /* expect_null_mutator_alloc_region */);
1674 }
1675 return NULL;
1676 }
1678 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1679 HeapWord* new_end) {
1680 assert(old_end != new_end, "don't call this otherwise");
1681 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1683 // Update the committed mem region.
1684 _g1_committed.set_end(new_end);
1685 // Tell the card table about the update.
1686 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1687 // Tell the BOT about the update.
1688 _bot_shared->resize(_g1_committed.word_size());
1689 }
1691 bool G1CollectedHeap::expand(size_t expand_bytes) {
1692 size_t old_mem_size = _g1_storage.committed_size();
1693 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1694 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1695 HeapRegion::GrainBytes);
1696 ergo_verbose2(ErgoHeapSizing,
1697 "expand the heap",
1698 ergo_format_byte("requested expansion amount")
1699 ergo_format_byte("attempted expansion amount"),
1700 expand_bytes, aligned_expand_bytes);
1702 // First commit the memory.
1703 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1704 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1705 if (successful) {
1706 // Then propagate this update to the necessary data structures.
1707 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1708 update_committed_space(old_end, new_end);
1710 FreeRegionList expansion_list("Local Expansion List");
1711 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1712 assert(mr.start() == old_end, "post-condition");
1713 // mr might be a smaller region than what was requested if
1714 // expand_by() was unable to allocate the HeapRegion instances
1715 assert(mr.end() <= new_end, "post-condition");
1717 size_t actual_expand_bytes = mr.byte_size();
1718 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1719 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1720 "post-condition");
1721 if (actual_expand_bytes < aligned_expand_bytes) {
1722 // We could not expand _hrs to the desired size. In this case we
1723 // need to shrink the committed space accordingly.
1724 assert(mr.end() < new_end, "invariant");
1726 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1727 // First uncommit the memory.
1728 _g1_storage.shrink_by(diff_bytes);
1729 // Then propagate this update to the necessary data structures.
1730 update_committed_space(new_end, mr.end());
1731 }
1732 _free_list.add_as_tail(&expansion_list);
1734 if (_hr_printer.is_active()) {
1735 HeapWord* curr = mr.start();
1736 while (curr < mr.end()) {
1737 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1738 _hr_printer.commit(curr, curr_end);
1739 curr = curr_end;
1740 }
1741 assert(curr == mr.end(), "post-condition");
1742 }
1743 g1_policy()->record_new_heap_size(n_regions());
1744 } else {
1745 ergo_verbose0(ErgoHeapSizing,
1746 "did not expand the heap",
1747 ergo_format_reason("heap expansion operation failed"));
1748 // The expansion of the virtual storage space was unsuccessful.
1749 // Let's see if it was because we ran out of swap.
1750 if (G1ExitOnExpansionFailure &&
1751 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1752 // We had head room...
1753 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1754 }
1755 }
1756 return successful;
1757 }
1759 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1760 size_t old_mem_size = _g1_storage.committed_size();
1761 size_t aligned_shrink_bytes =
1762 ReservedSpace::page_align_size_down(shrink_bytes);
1763 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1764 HeapRegion::GrainBytes);
1765 size_t num_regions_deleted = 0;
1766 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1767 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1768 assert(mr.end() == old_end, "post-condition");
1770 ergo_verbose3(ErgoHeapSizing,
1771 "shrink the heap",
1772 ergo_format_byte("requested shrinking amount")
1773 ergo_format_byte("aligned shrinking amount")
1774 ergo_format_byte("attempted shrinking amount"),
1775 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1776 if (mr.byte_size() > 0) {
1777 if (_hr_printer.is_active()) {
1778 HeapWord* curr = mr.end();
1779 while (curr > mr.start()) {
1780 HeapWord* curr_end = curr;
1781 curr -= HeapRegion::GrainWords;
1782 _hr_printer.uncommit(curr, curr_end);
1783 }
1784 assert(curr == mr.start(), "post-condition");
1785 }
1787 _g1_storage.shrink_by(mr.byte_size());
1788 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1789 assert(mr.start() == new_end, "post-condition");
1791 _expansion_regions += num_regions_deleted;
1792 update_committed_space(old_end, new_end);
1793 HeapRegionRemSet::shrink_heap(n_regions());
1794 g1_policy()->record_new_heap_size(n_regions());
1795 } else {
1796 ergo_verbose0(ErgoHeapSizing,
1797 "did not shrink the heap",
1798 ergo_format_reason("heap shrinking operation failed"));
1799 }
1800 }
1802 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1803 verify_region_sets_optional();
1805 // We should only reach here at the end of a Full GC which means we
1806 // should not not be holding to any GC alloc regions. The method
1807 // below will make sure of that and do any remaining clean up.
1808 abandon_gc_alloc_regions();
1810 // Instead of tearing down / rebuilding the free lists here, we
1811 // could instead use the remove_all_pending() method on free_list to
1812 // remove only the ones that we need to remove.
1813 tear_down_region_sets(true /* free_list_only */);
1814 shrink_helper(shrink_bytes);
1815 rebuild_region_sets(true /* free_list_only */);
1817 _hrs.verify_optional();
1818 verify_region_sets_optional();
1819 }
1821 // Public methods.
1823 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1824 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1825 #endif // _MSC_VER
1828 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1829 SharedHeap(policy_),
1830 _g1_policy(policy_),
1831 _dirty_card_queue_set(false),
1832 _into_cset_dirty_card_queue_set(false),
1833 _is_alive_closure_cm(this),
1834 _is_alive_closure_stw(this),
1835 _ref_processor_cm(NULL),
1836 _ref_processor_stw(NULL),
1837 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1838 _bot_shared(NULL),
1839 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1840 _evac_failure_scan_stack(NULL) ,
1841 _mark_in_progress(false),
1842 _cg1r(NULL), _summary_bytes_used(0),
1843 _g1mm(NULL),
1844 _refine_cte_cl(NULL),
1845 _full_collection(false),
1846 _free_list("Master Free List"),
1847 _secondary_free_list("Secondary Free List"),
1848 _old_set("Old Set"),
1849 _humongous_set("Master Humongous Set"),
1850 _free_regions_coming(false),
1851 _young_list(new YoungList(this)),
1852 _gc_time_stamp(0),
1853 _retained_old_gc_alloc_region(NULL),
1854 _expand_heap_after_alloc_failure(true),
1855 _surviving_young_words(NULL),
1856 _full_collections_completed(0),
1857 _in_cset_fast_test(NULL),
1858 _in_cset_fast_test_base(NULL),
1859 _dirty_cards_region_list(NULL),
1860 _worker_cset_start_region(NULL),
1861 _worker_cset_start_region_time_stamp(NULL) {
1862 _g1h = this; // To catch bugs.
1863 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1864 vm_exit_during_initialization("Failed necessary allocation.");
1865 }
1867 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1869 int n_queues = MAX2((int)ParallelGCThreads, 1);
1870 _task_queues = new RefToScanQueueSet(n_queues);
1872 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1873 assert(n_rem_sets > 0, "Invariant.");
1875 HeapRegionRemSetIterator** iter_arr =
1876 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1877 for (int i = 0; i < n_queues; i++) {
1878 iter_arr[i] = new HeapRegionRemSetIterator();
1879 }
1880 _rem_set_iterator = iter_arr;
1882 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues);
1883 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues);
1885 for (int i = 0; i < n_queues; i++) {
1886 RefToScanQueue* q = new RefToScanQueue();
1887 q->initialize();
1888 _task_queues->register_queue(i, q);
1889 }
1891 clear_cset_start_regions();
1893 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1894 }
1896 jint G1CollectedHeap::initialize() {
1897 CollectedHeap::pre_initialize();
1898 os::enable_vtime();
1900 // Necessary to satisfy locking discipline assertions.
1902 MutexLocker x(Heap_lock);
1904 // We have to initialize the printer before committing the heap, as
1905 // it will be used then.
1906 _hr_printer.set_active(G1PrintHeapRegions);
1908 // While there are no constraints in the GC code that HeapWordSize
1909 // be any particular value, there are multiple other areas in the
1910 // system which believe this to be true (e.g. oop->object_size in some
1911 // cases incorrectly returns the size in wordSize units rather than
1912 // HeapWordSize).
1913 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1915 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1916 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1918 // Ensure that the sizes are properly aligned.
1919 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1920 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1922 _cg1r = new ConcurrentG1Refine();
1924 // Reserve the maximum.
1925 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1926 // Includes the perm-gen.
1928 // When compressed oops are enabled, the preferred heap base
1929 // is calculated by subtracting the requested size from the
1930 // 32Gb boundary and using the result as the base address for
1931 // heap reservation. If the requested size is not aligned to
1932 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1933 // into the ReservedHeapSpace constructor) then the actual
1934 // base of the reserved heap may end up differing from the
1935 // address that was requested (i.e. the preferred heap base).
1936 // If this happens then we could end up using a non-optimal
1937 // compressed oops mode.
1939 // Since max_byte_size is aligned to the size of a heap region (checked
1940 // above), we also need to align the perm gen size as it might not be.
1941 const size_t total_reserved = max_byte_size +
1942 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1943 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1945 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1947 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1948 UseLargePages, addr);
1950 if (UseCompressedOops) {
1951 if (addr != NULL && !heap_rs.is_reserved()) {
1952 // Failed to reserve at specified address - the requested memory
1953 // region is taken already, for example, by 'java' launcher.
1954 // Try again to reserver heap higher.
1955 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1957 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1958 UseLargePages, addr);
1960 if (addr != NULL && !heap_rs0.is_reserved()) {
1961 // Failed to reserve at specified address again - give up.
1962 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1963 assert(addr == NULL, "");
1965 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1966 UseLargePages, addr);
1967 heap_rs = heap_rs1;
1968 } else {
1969 heap_rs = heap_rs0;
1970 }
1971 }
1972 }
1974 if (!heap_rs.is_reserved()) {
1975 vm_exit_during_initialization("Could not reserve enough space for object heap");
1976 return JNI_ENOMEM;
1977 }
1979 // It is important to do this in a way such that concurrent readers can't
1980 // temporarily think somethings in the heap. (I've actually seen this
1981 // happen in asserts: DLD.)
1982 _reserved.set_word_size(0);
1983 _reserved.set_start((HeapWord*)heap_rs.base());
1984 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1986 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1988 // Create the gen rem set (and barrier set) for the entire reserved region.
1989 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1990 set_barrier_set(rem_set()->bs());
1991 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1992 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1993 } else {
1994 vm_exit_during_initialization("G1 requires a mod ref bs.");
1995 return JNI_ENOMEM;
1996 }
1998 // Also create a G1 rem set.
1999 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2000 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2001 } else {
2002 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2003 return JNI_ENOMEM;
2004 }
2006 // Carve out the G1 part of the heap.
2008 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2009 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2010 g1_rs.size()/HeapWordSize);
2011 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
2013 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2015 _g1_storage.initialize(g1_rs, 0);
2016 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2017 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2018 (HeapWord*) _g1_reserved.end(),
2019 _expansion_regions);
2021 // 6843694 - ensure that the maximum region index can fit
2022 // in the remembered set structures.
2023 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2024 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2026 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2027 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2028 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2029 "too many cards per region");
2031 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2033 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2034 heap_word_size(init_byte_size));
2036 _g1h = this;
2038 _in_cset_fast_test_length = max_regions();
2039 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2041 // We're biasing _in_cset_fast_test to avoid subtracting the
2042 // beginning of the heap every time we want to index; basically
2043 // it's the same with what we do with the card table.
2044 _in_cset_fast_test = _in_cset_fast_test_base -
2045 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2047 // Clear the _cset_fast_test bitmap in anticipation of adding
2048 // regions to the incremental collection set for the first
2049 // evacuation pause.
2050 clear_cset_fast_test();
2052 // Create the ConcurrentMark data structure and thread.
2053 // (Must do this late, so that "max_regions" is defined.)
2054 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
2055 _cmThread = _cm->cmThread();
2057 // Initialize the from_card cache structure of HeapRegionRemSet.
2058 HeapRegionRemSet::init_heap(max_regions());
2060 // Now expand into the initial heap size.
2061 if (!expand(init_byte_size)) {
2062 vm_exit_during_initialization("Failed to allocate initial heap.");
2063 return JNI_ENOMEM;
2064 }
2066 // Perform any initialization actions delegated to the policy.
2067 g1_policy()->init();
2069 _refine_cte_cl =
2070 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2071 g1_rem_set(),
2072 concurrent_g1_refine());
2073 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2075 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2076 SATB_Q_FL_lock,
2077 G1SATBProcessCompletedThreshold,
2078 Shared_SATB_Q_lock);
2080 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2081 DirtyCardQ_FL_lock,
2082 concurrent_g1_refine()->yellow_zone(),
2083 concurrent_g1_refine()->red_zone(),
2084 Shared_DirtyCardQ_lock);
2086 if (G1DeferredRSUpdate) {
2087 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2088 DirtyCardQ_FL_lock,
2089 -1, // never trigger processing
2090 -1, // no limit on length
2091 Shared_DirtyCardQ_lock,
2092 &JavaThread::dirty_card_queue_set());
2093 }
2095 // Initialize the card queue set used to hold cards containing
2096 // references into the collection set.
2097 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2098 DirtyCardQ_FL_lock,
2099 -1, // never trigger processing
2100 -1, // no limit on length
2101 Shared_DirtyCardQ_lock,
2102 &JavaThread::dirty_card_queue_set());
2104 // In case we're keeping closure specialization stats, initialize those
2105 // counts and that mechanism.
2106 SpecializationStats::clear();
2108 // Do later initialization work for concurrent refinement.
2109 _cg1r->init();
2111 // Here we allocate the dummy full region that is required by the
2112 // G1AllocRegion class. If we don't pass an address in the reserved
2113 // space here, lots of asserts fire.
2115 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2116 _g1_reserved.start());
2117 // We'll re-use the same region whether the alloc region will
2118 // require BOT updates or not and, if it doesn't, then a non-young
2119 // region will complain that it cannot support allocations without
2120 // BOT updates. So we'll tag the dummy region as young to avoid that.
2121 dummy_region->set_young();
2122 // Make sure it's full.
2123 dummy_region->set_top(dummy_region->end());
2124 G1AllocRegion::setup(this, dummy_region);
2126 init_mutator_alloc_region();
2128 // Do create of the monitoring and management support so that
2129 // values in the heap have been properly initialized.
2130 _g1mm = new G1MonitoringSupport(this);
2132 return JNI_OK;
2133 }
2135 void G1CollectedHeap::ref_processing_init() {
2136 // Reference processing in G1 currently works as follows:
2137 //
2138 // * There are two reference processor instances. One is
2139 // used to record and process discovered references
2140 // during concurrent marking; the other is used to
2141 // record and process references during STW pauses
2142 // (both full and incremental).
2143 // * Both ref processors need to 'span' the entire heap as
2144 // the regions in the collection set may be dotted around.
2145 //
2146 // * For the concurrent marking ref processor:
2147 // * Reference discovery is enabled at initial marking.
2148 // * Reference discovery is disabled and the discovered
2149 // references processed etc during remarking.
2150 // * Reference discovery is MT (see below).
2151 // * Reference discovery requires a barrier (see below).
2152 // * Reference processing may or may not be MT
2153 // (depending on the value of ParallelRefProcEnabled
2154 // and ParallelGCThreads).
2155 // * A full GC disables reference discovery by the CM
2156 // ref processor and abandons any entries on it's
2157 // discovered lists.
2158 //
2159 // * For the STW processor:
2160 // * Non MT discovery is enabled at the start of a full GC.
2161 // * Processing and enqueueing during a full GC is non-MT.
2162 // * During a full GC, references are processed after marking.
2163 //
2164 // * Discovery (may or may not be MT) is enabled at the start
2165 // of an incremental evacuation pause.
2166 // * References are processed near the end of a STW evacuation pause.
2167 // * For both types of GC:
2168 // * Discovery is atomic - i.e. not concurrent.
2169 // * Reference discovery will not need a barrier.
2171 SharedHeap::ref_processing_init();
2172 MemRegion mr = reserved_region();
2174 // Concurrent Mark ref processor
2175 _ref_processor_cm =
2176 new ReferenceProcessor(mr, // span
2177 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2178 // mt processing
2179 (int) ParallelGCThreads,
2180 // degree of mt processing
2181 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2182 // mt discovery
2183 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2184 // degree of mt discovery
2185 false,
2186 // Reference discovery is not atomic
2187 &_is_alive_closure_cm,
2188 // is alive closure
2189 // (for efficiency/performance)
2190 true);
2191 // Setting next fields of discovered
2192 // lists requires a barrier.
2194 // STW ref processor
2195 _ref_processor_stw =
2196 new ReferenceProcessor(mr, // span
2197 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2198 // mt processing
2199 MAX2((int)ParallelGCThreads, 1),
2200 // degree of mt processing
2201 (ParallelGCThreads > 1),
2202 // mt discovery
2203 MAX2((int)ParallelGCThreads, 1),
2204 // degree of mt discovery
2205 true,
2206 // Reference discovery is atomic
2207 &_is_alive_closure_stw,
2208 // is alive closure
2209 // (for efficiency/performance)
2210 false);
2211 // Setting next fields of discovered
2212 // lists requires a barrier.
2213 }
2215 size_t G1CollectedHeap::capacity() const {
2216 return _g1_committed.byte_size();
2217 }
2219 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2220 DirtyCardQueue* into_cset_dcq,
2221 bool concurrent,
2222 int worker_i) {
2223 // Clean cards in the hot card cache
2224 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2226 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2227 int n_completed_buffers = 0;
2228 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2229 n_completed_buffers++;
2230 }
2231 g1_policy()->record_update_rs_processed_buffers(worker_i,
2232 (double) n_completed_buffers);
2233 dcqs.clear_n_completed_buffers();
2234 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2235 }
2238 // Computes the sum of the storage used by the various regions.
2240 size_t G1CollectedHeap::used() const {
2241 assert(Heap_lock->owner() != NULL,
2242 "Should be owned on this thread's behalf.");
2243 size_t result = _summary_bytes_used;
2244 // Read only once in case it is set to NULL concurrently
2245 HeapRegion* hr = _mutator_alloc_region.get();
2246 if (hr != NULL)
2247 result += hr->used();
2248 return result;
2249 }
2251 size_t G1CollectedHeap::used_unlocked() const {
2252 size_t result = _summary_bytes_used;
2253 return result;
2254 }
2256 class SumUsedClosure: public HeapRegionClosure {
2257 size_t _used;
2258 public:
2259 SumUsedClosure() : _used(0) {}
2260 bool doHeapRegion(HeapRegion* r) {
2261 if (!r->continuesHumongous()) {
2262 _used += r->used();
2263 }
2264 return false;
2265 }
2266 size_t result() { return _used; }
2267 };
2269 size_t G1CollectedHeap::recalculate_used() const {
2270 SumUsedClosure blk;
2271 heap_region_iterate(&blk);
2272 return blk.result();
2273 }
2275 size_t G1CollectedHeap::unsafe_max_alloc() {
2276 if (free_regions() > 0) return HeapRegion::GrainBytes;
2277 // otherwise, is there space in the current allocation region?
2279 // We need to store the current allocation region in a local variable
2280 // here. The problem is that this method doesn't take any locks and
2281 // there may be other threads which overwrite the current allocation
2282 // region field. attempt_allocation(), for example, sets it to NULL
2283 // and this can happen *after* the NULL check here but before the call
2284 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2285 // to be a problem in the optimized build, since the two loads of the
2286 // current allocation region field are optimized away.
2287 HeapRegion* hr = _mutator_alloc_region.get();
2288 if (hr == NULL) {
2289 return 0;
2290 }
2291 return hr->free();
2292 }
2294 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2295 return
2296 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2297 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2298 }
2300 #ifndef PRODUCT
2301 void G1CollectedHeap::allocate_dummy_regions() {
2302 // Let's fill up most of the region
2303 size_t word_size = HeapRegion::GrainWords - 1024;
2304 // And as a result the region we'll allocate will be humongous.
2305 guarantee(isHumongous(word_size), "sanity");
2307 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2308 // Let's use the existing mechanism for the allocation
2309 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2310 if (dummy_obj != NULL) {
2311 MemRegion mr(dummy_obj, word_size);
2312 CollectedHeap::fill_with_object(mr);
2313 } else {
2314 // If we can't allocate once, we probably cannot allocate
2315 // again. Let's get out of the loop.
2316 break;
2317 }
2318 }
2319 }
2320 #endif // !PRODUCT
2322 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2323 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2325 // We assume that if concurrent == true, then the caller is a
2326 // concurrent thread that was joined the Suspendible Thread
2327 // Set. If there's ever a cheap way to check this, we should add an
2328 // assert here.
2330 // We have already incremented _total_full_collections at the start
2331 // of the GC, so total_full_collections() represents how many full
2332 // collections have been started.
2333 unsigned int full_collections_started = total_full_collections();
2335 // Given that this method is called at the end of a Full GC or of a
2336 // concurrent cycle, and those can be nested (i.e., a Full GC can
2337 // interrupt a concurrent cycle), the number of full collections
2338 // completed should be either one (in the case where there was no
2339 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2340 // behind the number of full collections started.
2342 // This is the case for the inner caller, i.e. a Full GC.
2343 assert(concurrent ||
2344 (full_collections_started == _full_collections_completed + 1) ||
2345 (full_collections_started == _full_collections_completed + 2),
2346 err_msg("for inner caller (Full GC): full_collections_started = %u "
2347 "is inconsistent with _full_collections_completed = %u",
2348 full_collections_started, _full_collections_completed));
2350 // This is the case for the outer caller, i.e. the concurrent cycle.
2351 assert(!concurrent ||
2352 (full_collections_started == _full_collections_completed + 1),
2353 err_msg("for outer caller (concurrent cycle): "
2354 "full_collections_started = %u "
2355 "is inconsistent with _full_collections_completed = %u",
2356 full_collections_started, _full_collections_completed));
2358 _full_collections_completed += 1;
2360 // We need to clear the "in_progress" flag in the CM thread before
2361 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2362 // is set) so that if a waiter requests another System.gc() it doesn't
2363 // incorrectly see that a marking cyle is still in progress.
2364 if (concurrent) {
2365 _cmThread->clear_in_progress();
2366 }
2368 // This notify_all() will ensure that a thread that called
2369 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2370 // and it's waiting for a full GC to finish will be woken up. It is
2371 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2372 FullGCCount_lock->notify_all();
2373 }
2375 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2376 assert_at_safepoint(true /* should_be_vm_thread */);
2377 GCCauseSetter gcs(this, cause);
2378 switch (cause) {
2379 case GCCause::_heap_inspection:
2380 case GCCause::_heap_dump: {
2381 HandleMark hm;
2382 do_full_collection(false); // don't clear all soft refs
2383 break;
2384 }
2385 default: // XXX FIX ME
2386 ShouldNotReachHere(); // Unexpected use of this function
2387 }
2388 }
2390 void G1CollectedHeap::collect(GCCause::Cause cause) {
2391 // The caller doesn't have the Heap_lock
2392 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2394 unsigned int gc_count_before;
2395 unsigned int full_gc_count_before;
2396 {
2397 MutexLocker ml(Heap_lock);
2399 // Read the GC count while holding the Heap_lock
2400 gc_count_before = SharedHeap::heap()->total_collections();
2401 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2402 }
2404 if (should_do_concurrent_full_gc(cause)) {
2405 // Schedule an initial-mark evacuation pause that will start a
2406 // concurrent cycle. We're setting word_size to 0 which means that
2407 // we are not requesting a post-GC allocation.
2408 VM_G1IncCollectionPause op(gc_count_before,
2409 0, /* word_size */
2410 true, /* should_initiate_conc_mark */
2411 g1_policy()->max_pause_time_ms(),
2412 cause);
2413 VMThread::execute(&op);
2414 } else {
2415 if (cause == GCCause::_gc_locker
2416 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2418 // Schedule a standard evacuation pause. We're setting word_size
2419 // to 0 which means that we are not requesting a post-GC allocation.
2420 VM_G1IncCollectionPause op(gc_count_before,
2421 0, /* word_size */
2422 false, /* should_initiate_conc_mark */
2423 g1_policy()->max_pause_time_ms(),
2424 cause);
2425 VMThread::execute(&op);
2426 } else {
2427 // Schedule a Full GC.
2428 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2429 VMThread::execute(&op);
2430 }
2431 }
2432 }
2434 bool G1CollectedHeap::is_in(const void* p) const {
2435 if (_g1_committed.contains(p)) {
2436 // Given that we know that p is in the committed space,
2437 // heap_region_containing_raw() should successfully
2438 // return the containing region.
2439 HeapRegion* hr = heap_region_containing_raw(p);
2440 return hr->is_in(p);
2441 } else {
2442 return _perm_gen->as_gen()->is_in(p);
2443 }
2444 }
2446 // Iteration functions.
2448 // Iterates an OopClosure over all ref-containing fields of objects
2449 // within a HeapRegion.
2451 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2452 MemRegion _mr;
2453 OopClosure* _cl;
2454 public:
2455 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2456 : _mr(mr), _cl(cl) {}
2457 bool doHeapRegion(HeapRegion* r) {
2458 if (! r->continuesHumongous()) {
2459 r->oop_iterate(_cl);
2460 }
2461 return false;
2462 }
2463 };
2465 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2466 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2467 heap_region_iterate(&blk);
2468 if (do_perm) {
2469 perm_gen()->oop_iterate(cl);
2470 }
2471 }
2473 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2474 IterateOopClosureRegionClosure blk(mr, cl);
2475 heap_region_iterate(&blk);
2476 if (do_perm) {
2477 perm_gen()->oop_iterate(cl);
2478 }
2479 }
2481 // Iterates an ObjectClosure over all objects within a HeapRegion.
2483 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2484 ObjectClosure* _cl;
2485 public:
2486 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2487 bool doHeapRegion(HeapRegion* r) {
2488 if (! r->continuesHumongous()) {
2489 r->object_iterate(_cl);
2490 }
2491 return false;
2492 }
2493 };
2495 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2496 IterateObjectClosureRegionClosure blk(cl);
2497 heap_region_iterate(&blk);
2498 if (do_perm) {
2499 perm_gen()->object_iterate(cl);
2500 }
2501 }
2503 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2504 // FIXME: is this right?
2505 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2506 }
2508 // Calls a SpaceClosure on a HeapRegion.
2510 class SpaceClosureRegionClosure: public HeapRegionClosure {
2511 SpaceClosure* _cl;
2512 public:
2513 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2514 bool doHeapRegion(HeapRegion* r) {
2515 _cl->do_space(r);
2516 return false;
2517 }
2518 };
2520 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2521 SpaceClosureRegionClosure blk(cl);
2522 heap_region_iterate(&blk);
2523 }
2525 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2526 _hrs.iterate(cl);
2527 }
2529 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2530 HeapRegionClosure* cl) const {
2531 _hrs.iterate_from(r, cl);
2532 }
2534 void
2535 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2536 uint worker,
2537 uint no_of_par_workers,
2538 jint claim_value) {
2539 const size_t regions = n_regions();
2540 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2541 no_of_par_workers :
2542 1);
2543 assert(UseDynamicNumberOfGCThreads ||
2544 no_of_par_workers == workers()->total_workers(),
2545 "Non dynamic should use fixed number of workers");
2546 // try to spread out the starting points of the workers
2547 const size_t start_index = regions / max_workers * (size_t) worker;
2549 // each worker will actually look at all regions
2550 for (size_t count = 0; count < regions; ++count) {
2551 const size_t index = (start_index + count) % regions;
2552 assert(0 <= index && index < regions, "sanity");
2553 HeapRegion* r = region_at(index);
2554 // we'll ignore "continues humongous" regions (we'll process them
2555 // when we come across their corresponding "start humongous"
2556 // region) and regions already claimed
2557 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2558 continue;
2559 }
2560 // OK, try to claim it
2561 if (r->claimHeapRegion(claim_value)) {
2562 // success!
2563 assert(!r->continuesHumongous(), "sanity");
2564 if (r->startsHumongous()) {
2565 // If the region is "starts humongous" we'll iterate over its
2566 // "continues humongous" first; in fact we'll do them
2567 // first. The order is important. In on case, calling the
2568 // closure on the "starts humongous" region might de-allocate
2569 // and clear all its "continues humongous" regions and, as a
2570 // result, we might end up processing them twice. So, we'll do
2571 // them first (notice: most closures will ignore them anyway) and
2572 // then we'll do the "starts humongous" region.
2573 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2574 HeapRegion* chr = region_at(ch_index);
2576 // if the region has already been claimed or it's not
2577 // "continues humongous" we're done
2578 if (chr->claim_value() == claim_value ||
2579 !chr->continuesHumongous()) {
2580 break;
2581 }
2583 // Noone should have claimed it directly. We can given
2584 // that we claimed its "starts humongous" region.
2585 assert(chr->claim_value() != claim_value, "sanity");
2586 assert(chr->humongous_start_region() == r, "sanity");
2588 if (chr->claimHeapRegion(claim_value)) {
2589 // we should always be able to claim it; noone else should
2590 // be trying to claim this region
2592 bool res2 = cl->doHeapRegion(chr);
2593 assert(!res2, "Should not abort");
2595 // Right now, this holds (i.e., no closure that actually
2596 // does something with "continues humongous" regions
2597 // clears them). We might have to weaken it in the future,
2598 // but let's leave these two asserts here for extra safety.
2599 assert(chr->continuesHumongous(), "should still be the case");
2600 assert(chr->humongous_start_region() == r, "sanity");
2601 } else {
2602 guarantee(false, "we should not reach here");
2603 }
2604 }
2605 }
2607 assert(!r->continuesHumongous(), "sanity");
2608 bool res = cl->doHeapRegion(r);
2609 assert(!res, "Should not abort");
2610 }
2611 }
2612 }
2614 class ResetClaimValuesClosure: public HeapRegionClosure {
2615 public:
2616 bool doHeapRegion(HeapRegion* r) {
2617 r->set_claim_value(HeapRegion::InitialClaimValue);
2618 return false;
2619 }
2620 };
2622 void G1CollectedHeap::reset_heap_region_claim_values() {
2623 ResetClaimValuesClosure blk;
2624 heap_region_iterate(&blk);
2625 }
2627 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2628 ResetClaimValuesClosure blk;
2629 collection_set_iterate(&blk);
2630 }
2632 #ifdef ASSERT
2633 // This checks whether all regions in the heap have the correct claim
2634 // value. I also piggy-backed on this a check to ensure that the
2635 // humongous_start_region() information on "continues humongous"
2636 // regions is correct.
2638 class CheckClaimValuesClosure : public HeapRegionClosure {
2639 private:
2640 jint _claim_value;
2641 size_t _failures;
2642 HeapRegion* _sh_region;
2643 public:
2644 CheckClaimValuesClosure(jint claim_value) :
2645 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2646 bool doHeapRegion(HeapRegion* r) {
2647 if (r->claim_value() != _claim_value) {
2648 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2649 "claim value = %d, should be %d",
2650 HR_FORMAT_PARAMS(r),
2651 r->claim_value(), _claim_value);
2652 ++_failures;
2653 }
2654 if (!r->isHumongous()) {
2655 _sh_region = NULL;
2656 } else if (r->startsHumongous()) {
2657 _sh_region = r;
2658 } else if (r->continuesHumongous()) {
2659 if (r->humongous_start_region() != _sh_region) {
2660 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2661 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2662 HR_FORMAT_PARAMS(r),
2663 r->humongous_start_region(),
2664 _sh_region);
2665 ++_failures;
2666 }
2667 }
2668 return false;
2669 }
2670 size_t failures() {
2671 return _failures;
2672 }
2673 };
2675 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2676 CheckClaimValuesClosure cl(claim_value);
2677 heap_region_iterate(&cl);
2678 return cl.failures() == 0;
2679 }
2681 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2682 jint _claim_value;
2683 size_t _failures;
2685 public:
2686 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2687 _claim_value(claim_value),
2688 _failures(0) { }
2690 size_t failures() {
2691 return _failures;
2692 }
2694 bool doHeapRegion(HeapRegion* hr) {
2695 assert(hr->in_collection_set(), "how?");
2696 assert(!hr->isHumongous(), "H-region in CSet");
2697 if (hr->claim_value() != _claim_value) {
2698 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2699 "claim value = %d, should be %d",
2700 HR_FORMAT_PARAMS(hr),
2701 hr->claim_value(), _claim_value);
2702 _failures += 1;
2703 }
2704 return false;
2705 }
2706 };
2708 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2709 CheckClaimValuesInCSetHRClosure cl(claim_value);
2710 collection_set_iterate(&cl);
2711 return cl.failures() == 0;
2712 }
2713 #endif // ASSERT
2715 // Clear the cached CSet starting regions and (more importantly)
2716 // the time stamps. Called when we reset the GC time stamp.
2717 void G1CollectedHeap::clear_cset_start_regions() {
2718 assert(_worker_cset_start_region != NULL, "sanity");
2719 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2721 int n_queues = MAX2((int)ParallelGCThreads, 1);
2722 for (int i = 0; i < n_queues; i++) {
2723 _worker_cset_start_region[i] = NULL;
2724 _worker_cset_start_region_time_stamp[i] = 0;
2725 }
2726 }
2728 // Given the id of a worker, obtain or calculate a suitable
2729 // starting region for iterating over the current collection set.
2730 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2731 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2733 HeapRegion* result = NULL;
2734 unsigned gc_time_stamp = get_gc_time_stamp();
2736 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2737 // Cached starting region for current worker was set
2738 // during the current pause - so it's valid.
2739 // Note: the cached starting heap region may be NULL
2740 // (when the collection set is empty).
2741 result = _worker_cset_start_region[worker_i];
2742 assert(result == NULL || result->in_collection_set(), "sanity");
2743 return result;
2744 }
2746 // The cached entry was not valid so let's calculate
2747 // a suitable starting heap region for this worker.
2749 // We want the parallel threads to start their collection
2750 // set iteration at different collection set regions to
2751 // avoid contention.
2752 // If we have:
2753 // n collection set regions
2754 // p threads
2755 // Then thread t will start at region floor ((t * n) / p)
2757 result = g1_policy()->collection_set();
2758 if (G1CollectedHeap::use_parallel_gc_threads()) {
2759 size_t cs_size = g1_policy()->cset_region_length();
2760 uint active_workers = workers()->active_workers();
2761 assert(UseDynamicNumberOfGCThreads ||
2762 active_workers == workers()->total_workers(),
2763 "Unless dynamic should use total workers");
2765 size_t end_ind = (cs_size * worker_i) / active_workers;
2766 size_t start_ind = 0;
2768 if (worker_i > 0 &&
2769 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2770 // Previous workers starting region is valid
2771 // so let's iterate from there
2772 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2773 result = _worker_cset_start_region[worker_i - 1];
2774 }
2776 for (size_t i = start_ind; i < end_ind; i++) {
2777 result = result->next_in_collection_set();
2778 }
2779 }
2781 // Note: the calculated starting heap region may be NULL
2782 // (when the collection set is empty).
2783 assert(result == NULL || result->in_collection_set(), "sanity");
2784 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2785 "should be updated only once per pause");
2786 _worker_cset_start_region[worker_i] = result;
2787 OrderAccess::storestore();
2788 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2789 return result;
2790 }
2792 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2793 HeapRegion* r = g1_policy()->collection_set();
2794 while (r != NULL) {
2795 HeapRegion* next = r->next_in_collection_set();
2796 if (cl->doHeapRegion(r)) {
2797 cl->incomplete();
2798 return;
2799 }
2800 r = next;
2801 }
2802 }
2804 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2805 HeapRegionClosure *cl) {
2806 if (r == NULL) {
2807 // The CSet is empty so there's nothing to do.
2808 return;
2809 }
2811 assert(r->in_collection_set(),
2812 "Start region must be a member of the collection set.");
2813 HeapRegion* cur = r;
2814 while (cur != NULL) {
2815 HeapRegion* next = cur->next_in_collection_set();
2816 if (cl->doHeapRegion(cur) && false) {
2817 cl->incomplete();
2818 return;
2819 }
2820 cur = next;
2821 }
2822 cur = g1_policy()->collection_set();
2823 while (cur != r) {
2824 HeapRegion* next = cur->next_in_collection_set();
2825 if (cl->doHeapRegion(cur) && false) {
2826 cl->incomplete();
2827 return;
2828 }
2829 cur = next;
2830 }
2831 }
2833 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2834 return n_regions() > 0 ? region_at(0) : NULL;
2835 }
2838 Space* G1CollectedHeap::space_containing(const void* addr) const {
2839 Space* res = heap_region_containing(addr);
2840 if (res == NULL)
2841 res = perm_gen()->space_containing(addr);
2842 return res;
2843 }
2845 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2846 Space* sp = space_containing(addr);
2847 if (sp != NULL) {
2848 return sp->block_start(addr);
2849 }
2850 return NULL;
2851 }
2853 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2854 Space* sp = space_containing(addr);
2855 assert(sp != NULL, "block_size of address outside of heap");
2856 return sp->block_size(addr);
2857 }
2859 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2860 Space* sp = space_containing(addr);
2861 return sp->block_is_obj(addr);
2862 }
2864 bool G1CollectedHeap::supports_tlab_allocation() const {
2865 return true;
2866 }
2868 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2869 return HeapRegion::GrainBytes;
2870 }
2872 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2873 // Return the remaining space in the cur alloc region, but not less than
2874 // the min TLAB size.
2876 // Also, this value can be at most the humongous object threshold,
2877 // since we can't allow tlabs to grow big enough to accomodate
2878 // humongous objects.
2880 HeapRegion* hr = _mutator_alloc_region.get();
2881 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2882 if (hr == NULL) {
2883 return max_tlab_size;
2884 } else {
2885 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2886 }
2887 }
2889 size_t G1CollectedHeap::max_capacity() const {
2890 return _g1_reserved.byte_size();
2891 }
2893 jlong G1CollectedHeap::millis_since_last_gc() {
2894 // assert(false, "NYI");
2895 return 0;
2896 }
2898 void G1CollectedHeap::prepare_for_verify() {
2899 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2900 ensure_parsability(false);
2901 }
2902 g1_rem_set()->prepare_for_verify();
2903 }
2905 class VerifyLivenessOopClosure: public OopClosure {
2906 G1CollectedHeap* _g1h;
2907 VerifyOption _vo;
2908 public:
2909 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2910 _g1h(g1h), _vo(vo)
2911 { }
2912 void do_oop(narrowOop *p) { do_oop_work(p); }
2913 void do_oop( oop *p) { do_oop_work(p); }
2915 template <class T> void do_oop_work(T *p) {
2916 oop obj = oopDesc::load_decode_heap_oop(p);
2917 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2918 "Dead object referenced by a not dead object");
2919 }
2920 };
2922 class VerifyObjsInRegionClosure: public ObjectClosure {
2923 private:
2924 G1CollectedHeap* _g1h;
2925 size_t _live_bytes;
2926 HeapRegion *_hr;
2927 VerifyOption _vo;
2928 public:
2929 // _vo == UsePrevMarking -> use "prev" marking information,
2930 // _vo == UseNextMarking -> use "next" marking information,
2931 // _vo == UseMarkWord -> use mark word from object header.
2932 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2933 : _live_bytes(0), _hr(hr), _vo(vo) {
2934 _g1h = G1CollectedHeap::heap();
2935 }
2936 void do_object(oop o) {
2937 VerifyLivenessOopClosure isLive(_g1h, _vo);
2938 assert(o != NULL, "Huh?");
2939 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2940 // If the object is alive according to the mark word,
2941 // then verify that the marking information agrees.
2942 // Note we can't verify the contra-positive of the
2943 // above: if the object is dead (according to the mark
2944 // word), it may not be marked, or may have been marked
2945 // but has since became dead, or may have been allocated
2946 // since the last marking.
2947 if (_vo == VerifyOption_G1UseMarkWord) {
2948 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2949 }
2951 o->oop_iterate(&isLive);
2952 if (!_hr->obj_allocated_since_prev_marking(o)) {
2953 size_t obj_size = o->size(); // Make sure we don't overflow
2954 _live_bytes += (obj_size * HeapWordSize);
2955 }
2956 }
2957 }
2958 size_t live_bytes() { return _live_bytes; }
2959 };
2961 class PrintObjsInRegionClosure : public ObjectClosure {
2962 HeapRegion *_hr;
2963 G1CollectedHeap *_g1;
2964 public:
2965 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2966 _g1 = G1CollectedHeap::heap();
2967 };
2969 void do_object(oop o) {
2970 if (o != NULL) {
2971 HeapWord *start = (HeapWord *) o;
2972 size_t word_sz = o->size();
2973 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2974 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2975 (void*) o, word_sz,
2976 _g1->isMarkedPrev(o),
2977 _g1->isMarkedNext(o),
2978 _hr->obj_allocated_since_prev_marking(o));
2979 HeapWord *end = start + word_sz;
2980 HeapWord *cur;
2981 int *val;
2982 for (cur = start; cur < end; cur++) {
2983 val = (int *) cur;
2984 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2985 }
2986 }
2987 }
2988 };
2990 class VerifyRegionClosure: public HeapRegionClosure {
2991 private:
2992 bool _allow_dirty;
2993 bool _par;
2994 VerifyOption _vo;
2995 bool _failures;
2996 public:
2997 // _vo == UsePrevMarking -> use "prev" marking information,
2998 // _vo == UseNextMarking -> use "next" marking information,
2999 // _vo == UseMarkWord -> use mark word from object header.
3000 VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
3001 : _allow_dirty(allow_dirty),
3002 _par(par),
3003 _vo(vo),
3004 _failures(false) {}
3006 bool failures() {
3007 return _failures;
3008 }
3010 bool doHeapRegion(HeapRegion* r) {
3011 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
3012 "Should be unclaimed at verify points.");
3013 if (!r->continuesHumongous()) {
3014 bool failures = false;
3015 r->verify(_allow_dirty, _vo, &failures);
3016 if (failures) {
3017 _failures = true;
3018 } else {
3019 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3020 r->object_iterate(¬_dead_yet_cl);
3021 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3022 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3023 "max_live_bytes "SIZE_FORMAT" "
3024 "< calculated "SIZE_FORMAT,
3025 r->bottom(), r->end(),
3026 r->max_live_bytes(),
3027 not_dead_yet_cl.live_bytes());
3028 _failures = true;
3029 }
3030 }
3031 }
3032 return false; // stop the region iteration if we hit a failure
3033 }
3034 };
3036 class VerifyRootsClosure: public OopsInGenClosure {
3037 private:
3038 G1CollectedHeap* _g1h;
3039 VerifyOption _vo;
3040 bool _failures;
3041 public:
3042 // _vo == UsePrevMarking -> use "prev" marking information,
3043 // _vo == UseNextMarking -> use "next" marking information,
3044 // _vo == UseMarkWord -> use mark word from object header.
3045 VerifyRootsClosure(VerifyOption vo) :
3046 _g1h(G1CollectedHeap::heap()),
3047 _vo(vo),
3048 _failures(false) { }
3050 bool failures() { return _failures; }
3052 template <class T> void do_oop_nv(T* p) {
3053 T heap_oop = oopDesc::load_heap_oop(p);
3054 if (!oopDesc::is_null(heap_oop)) {
3055 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3056 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3057 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3058 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3059 if (_vo == VerifyOption_G1UseMarkWord) {
3060 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3061 }
3062 obj->print_on(gclog_or_tty);
3063 _failures = true;
3064 }
3065 }
3066 }
3068 void do_oop(oop* p) { do_oop_nv(p); }
3069 void do_oop(narrowOop* p) { do_oop_nv(p); }
3070 };
3072 // This is the task used for parallel heap verification.
3074 class G1ParVerifyTask: public AbstractGangTask {
3075 private:
3076 G1CollectedHeap* _g1h;
3077 bool _allow_dirty;
3078 VerifyOption _vo;
3079 bool _failures;
3081 public:
3082 // _vo == UsePrevMarking -> use "prev" marking information,
3083 // _vo == UseNextMarking -> use "next" marking information,
3084 // _vo == UseMarkWord -> use mark word from object header.
3085 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
3086 AbstractGangTask("Parallel verify task"),
3087 _g1h(g1h),
3088 _allow_dirty(allow_dirty),
3089 _vo(vo),
3090 _failures(false) { }
3092 bool failures() {
3093 return _failures;
3094 }
3096 void work(uint worker_id) {
3097 HandleMark hm;
3098 VerifyRegionClosure blk(_allow_dirty, true, _vo);
3099 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3100 _g1h->workers()->active_workers(),
3101 HeapRegion::ParVerifyClaimValue);
3102 if (blk.failures()) {
3103 _failures = true;
3104 }
3105 }
3106 };
3108 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
3109 verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
3110 }
3112 void G1CollectedHeap::verify(bool allow_dirty,
3113 bool silent,
3114 VerifyOption vo) {
3115 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3116 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3117 VerifyRootsClosure rootsCl(vo);
3119 assert(Thread::current()->is_VM_thread(),
3120 "Expected to be executed serially by the VM thread at this point");
3122 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3124 // We apply the relevant closures to all the oops in the
3125 // system dictionary, the string table and the code cache.
3126 const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
3128 process_strong_roots(true, // activate StrongRootsScope
3129 true, // we set "collecting perm gen" to true,
3130 // so we don't reset the dirty cards in the perm gen.
3131 SharedHeap::ScanningOption(so), // roots scanning options
3132 &rootsCl,
3133 &blobsCl,
3134 &rootsCl);
3136 // If we're verifying after the marking phase of a Full GC then we can't
3137 // treat the perm gen as roots into the G1 heap. Some of the objects in
3138 // the perm gen may be dead and hence not marked. If one of these dead
3139 // objects is considered to be a root then we may end up with a false
3140 // "Root location <x> points to dead ob <y>" failure.
3141 if (vo != VerifyOption_G1UseMarkWord) {
3142 // Since we used "collecting_perm_gen" == true above, we will not have
3143 // checked the refs from perm into the G1-collected heap. We check those
3144 // references explicitly below. Whether the relevant cards are dirty
3145 // is checked further below in the rem set verification.
3146 if (!silent) { gclog_or_tty->print("Permgen roots "); }
3147 perm_gen()->oop_iterate(&rootsCl);
3148 }
3149 bool failures = rootsCl.failures();
3151 if (vo != VerifyOption_G1UseMarkWord) {
3152 // If we're verifying during a full GC then the region sets
3153 // will have been torn down at the start of the GC. Therefore
3154 // verifying the region sets will fail. So we only verify
3155 // the region sets when not in a full GC.
3156 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3157 verify_region_sets();
3158 }
3160 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3161 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3162 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3163 "sanity check");
3165 G1ParVerifyTask task(this, allow_dirty, vo);
3166 assert(UseDynamicNumberOfGCThreads ||
3167 workers()->active_workers() == workers()->total_workers(),
3168 "If not dynamic should be using all the workers");
3169 int n_workers = workers()->active_workers();
3170 set_par_threads(n_workers);
3171 workers()->run_task(&task);
3172 set_par_threads(0);
3173 if (task.failures()) {
3174 failures = true;
3175 }
3177 // Checks that the expected amount of parallel work was done.
3178 // The implication is that n_workers is > 0.
3179 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3180 "sanity check");
3182 reset_heap_region_claim_values();
3184 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3185 "sanity check");
3186 } else {
3187 VerifyRegionClosure blk(allow_dirty, false, vo);
3188 heap_region_iterate(&blk);
3189 if (blk.failures()) {
3190 failures = true;
3191 }
3192 }
3193 if (!silent) gclog_or_tty->print("RemSet ");
3194 rem_set()->verify();
3196 if (failures) {
3197 gclog_or_tty->print_cr("Heap:");
3198 // It helps to have the per-region information in the output to
3199 // help us track down what went wrong. This is why we call
3200 // print_extended_on() instead of print_on().
3201 print_extended_on(gclog_or_tty);
3202 gclog_or_tty->print_cr("");
3203 #ifndef PRODUCT
3204 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3205 concurrent_mark()->print_reachable("at-verification-failure",
3206 vo, false /* all */);
3207 }
3208 #endif
3209 gclog_or_tty->flush();
3210 }
3211 guarantee(!failures, "there should not have been any failures");
3212 } else {
3213 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3214 }
3215 }
3217 class PrintRegionClosure: public HeapRegionClosure {
3218 outputStream* _st;
3219 public:
3220 PrintRegionClosure(outputStream* st) : _st(st) {}
3221 bool doHeapRegion(HeapRegion* r) {
3222 r->print_on(_st);
3223 return false;
3224 }
3225 };
3227 void G1CollectedHeap::print_on(outputStream* st) const {
3228 st->print(" %-20s", "garbage-first heap");
3229 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3230 capacity()/K, used_unlocked()/K);
3231 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3232 _g1_storage.low_boundary(),
3233 _g1_storage.high(),
3234 _g1_storage.high_boundary());
3235 st->cr();
3236 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3237 size_t young_regions = _young_list->length();
3238 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3239 young_regions, young_regions * HeapRegion::GrainBytes / K);
3240 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3241 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3242 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3243 st->cr();
3244 perm()->as_gen()->print_on(st);
3245 }
3247 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3248 print_on(st);
3250 // Print the per-region information.
3251 st->cr();
3252 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), HS=humongous(starts), HC=humongous(continues), CS=collection set, F=free, TS=gc time stamp, PTAMS=previous top-at-mark-start, NTAMS=next top-at-mark-start)");
3253 PrintRegionClosure blk(st);
3254 heap_region_iterate(&blk);
3255 }
3257 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3258 if (G1CollectedHeap::use_parallel_gc_threads()) {
3259 workers()->print_worker_threads_on(st);
3260 }
3261 _cmThread->print_on(st);
3262 st->cr();
3263 _cm->print_worker_threads_on(st);
3264 _cg1r->print_worker_threads_on(st);
3265 st->cr();
3266 }
3268 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3269 if (G1CollectedHeap::use_parallel_gc_threads()) {
3270 workers()->threads_do(tc);
3271 }
3272 tc->do_thread(_cmThread);
3273 _cg1r->threads_do(tc);
3274 }
3276 void G1CollectedHeap::print_tracing_info() const {
3277 // We'll overload this to mean "trace GC pause statistics."
3278 if (TraceGen0Time || TraceGen1Time) {
3279 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3280 // to that.
3281 g1_policy()->print_tracing_info();
3282 }
3283 if (G1SummarizeRSetStats) {
3284 g1_rem_set()->print_summary_info();
3285 }
3286 if (G1SummarizeConcMark) {
3287 concurrent_mark()->print_summary_info();
3288 }
3289 g1_policy()->print_yg_surv_rate_info();
3290 SpecializationStats::print();
3291 }
3293 #ifndef PRODUCT
3294 // Helpful for debugging RSet issues.
3296 class PrintRSetsClosure : public HeapRegionClosure {
3297 private:
3298 const char* _msg;
3299 size_t _occupied_sum;
3301 public:
3302 bool doHeapRegion(HeapRegion* r) {
3303 HeapRegionRemSet* hrrs = r->rem_set();
3304 size_t occupied = hrrs->occupied();
3305 _occupied_sum += occupied;
3307 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3308 HR_FORMAT_PARAMS(r));
3309 if (occupied == 0) {
3310 gclog_or_tty->print_cr(" RSet is empty");
3311 } else {
3312 hrrs->print();
3313 }
3314 gclog_or_tty->print_cr("----------");
3315 return false;
3316 }
3318 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3319 gclog_or_tty->cr();
3320 gclog_or_tty->print_cr("========================================");
3321 gclog_or_tty->print_cr(msg);
3322 gclog_or_tty->cr();
3323 }
3325 ~PrintRSetsClosure() {
3326 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3327 gclog_or_tty->print_cr("========================================");
3328 gclog_or_tty->cr();
3329 }
3330 };
3332 void G1CollectedHeap::print_cset_rsets() {
3333 PrintRSetsClosure cl("Printing CSet RSets");
3334 collection_set_iterate(&cl);
3335 }
3337 void G1CollectedHeap::print_all_rsets() {
3338 PrintRSetsClosure cl("Printing All RSets");;
3339 heap_region_iterate(&cl);
3340 }
3341 #endif // PRODUCT
3343 G1CollectedHeap* G1CollectedHeap::heap() {
3344 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3345 "not a garbage-first heap");
3346 return _g1h;
3347 }
3349 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3350 // always_do_update_barrier = false;
3351 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3352 // Call allocation profiler
3353 AllocationProfiler::iterate_since_last_gc();
3354 // Fill TLAB's and such
3355 ensure_parsability(true);
3356 }
3358 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3359 // FIXME: what is this about?
3360 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3361 // is set.
3362 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3363 "derived pointer present"));
3364 // always_do_update_barrier = true;
3366 // We have just completed a GC. Update the soft reference
3367 // policy with the new heap occupancy
3368 Universe::update_heap_info_at_gc();
3369 }
3371 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3372 unsigned int gc_count_before,
3373 bool* succeeded) {
3374 assert_heap_not_locked_and_not_at_safepoint();
3375 g1_policy()->record_stop_world_start();
3376 VM_G1IncCollectionPause op(gc_count_before,
3377 word_size,
3378 false, /* should_initiate_conc_mark */
3379 g1_policy()->max_pause_time_ms(),
3380 GCCause::_g1_inc_collection_pause);
3381 VMThread::execute(&op);
3383 HeapWord* result = op.result();
3384 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3385 assert(result == NULL || ret_succeeded,
3386 "the result should be NULL if the VM did not succeed");
3387 *succeeded = ret_succeeded;
3389 assert_heap_not_locked();
3390 return result;
3391 }
3393 void
3394 G1CollectedHeap::doConcurrentMark() {
3395 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3396 if (!_cmThread->in_progress()) {
3397 _cmThread->set_started();
3398 CGC_lock->notify();
3399 }
3400 }
3402 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3403 bool young) {
3404 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3405 }
3407 void G1CollectedHeap::check_if_region_is_too_expensive(double
3408 predicted_time_ms) {
3409 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3410 }
3412 size_t G1CollectedHeap::pending_card_num() {
3413 size_t extra_cards = 0;
3414 JavaThread *curr = Threads::first();
3415 while (curr != NULL) {
3416 DirtyCardQueue& dcq = curr->dirty_card_queue();
3417 extra_cards += dcq.size();
3418 curr = curr->next();
3419 }
3420 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3421 size_t buffer_size = dcqs.buffer_size();
3422 size_t buffer_num = dcqs.completed_buffers_num();
3423 return buffer_size * buffer_num + extra_cards;
3424 }
3426 size_t G1CollectedHeap::max_pending_card_num() {
3427 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3428 size_t buffer_size = dcqs.buffer_size();
3429 size_t buffer_num = dcqs.completed_buffers_num();
3430 int thread_num = Threads::number_of_threads();
3431 return (buffer_num + thread_num) * buffer_size;
3432 }
3434 size_t G1CollectedHeap::cards_scanned() {
3435 return g1_rem_set()->cardsScanned();
3436 }
3438 void
3439 G1CollectedHeap::setup_surviving_young_words() {
3440 guarantee( _surviving_young_words == NULL, "pre-condition" );
3441 size_t array_length = g1_policy()->young_cset_region_length();
3442 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3443 if (_surviving_young_words == NULL) {
3444 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3445 "Not enough space for young surv words summary.");
3446 }
3447 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3448 #ifdef ASSERT
3449 for (size_t i = 0; i < array_length; ++i) {
3450 assert( _surviving_young_words[i] == 0, "memset above" );
3451 }
3452 #endif // !ASSERT
3453 }
3455 void
3456 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3457 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3458 size_t array_length = g1_policy()->young_cset_region_length();
3459 for (size_t i = 0; i < array_length; ++i)
3460 _surviving_young_words[i] += surv_young_words[i];
3461 }
3463 void
3464 G1CollectedHeap::cleanup_surviving_young_words() {
3465 guarantee( _surviving_young_words != NULL, "pre-condition" );
3466 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3467 _surviving_young_words = NULL;
3468 }
3470 #ifdef ASSERT
3471 class VerifyCSetClosure: public HeapRegionClosure {
3472 public:
3473 bool doHeapRegion(HeapRegion* hr) {
3474 // Here we check that the CSet region's RSet is ready for parallel
3475 // iteration. The fields that we'll verify are only manipulated
3476 // when the region is part of a CSet and is collected. Afterwards,
3477 // we reset these fields when we clear the region's RSet (when the
3478 // region is freed) so they are ready when the region is
3479 // re-allocated. The only exception to this is if there's an
3480 // evacuation failure and instead of freeing the region we leave
3481 // it in the heap. In that case, we reset these fields during
3482 // evacuation failure handling.
3483 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3485 // Here's a good place to add any other checks we'd like to
3486 // perform on CSet regions.
3487 return false;
3488 }
3489 };
3490 #endif // ASSERT
3492 #if TASKQUEUE_STATS
3493 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3494 st->print_raw_cr("GC Task Stats");
3495 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3496 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3497 }
3499 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3500 print_taskqueue_stats_hdr(st);
3502 TaskQueueStats totals;
3503 const int n = workers() != NULL ? workers()->total_workers() : 1;
3504 for (int i = 0; i < n; ++i) {
3505 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3506 totals += task_queue(i)->stats;
3507 }
3508 st->print_raw("tot "); totals.print(st); st->cr();
3510 DEBUG_ONLY(totals.verify());
3511 }
3513 void G1CollectedHeap::reset_taskqueue_stats() {
3514 const int n = workers() != NULL ? workers()->total_workers() : 1;
3515 for (int i = 0; i < n; ++i) {
3516 task_queue(i)->stats.reset();
3517 }
3518 }
3519 #endif // TASKQUEUE_STATS
3521 bool
3522 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3523 assert_at_safepoint(true /* should_be_vm_thread */);
3524 guarantee(!is_gc_active(), "collection is not reentrant");
3526 if (GC_locker::check_active_before_gc()) {
3527 return false;
3528 }
3530 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3531 ResourceMark rm;
3533 if (PrintHeapAtGC) {
3534 Universe::print_heap_before_gc();
3535 }
3537 HRSPhaseSetter x(HRSPhaseEvacuation);
3538 verify_region_sets_optional();
3539 verify_dirty_young_regions();
3541 {
3542 // This call will decide whether this pause is an initial-mark
3543 // pause. If it is, during_initial_mark_pause() will return true
3544 // for the duration of this pause.
3545 g1_policy()->decide_on_conc_mark_initiation();
3547 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3548 assert(!g1_policy()->during_initial_mark_pause() ||
3549 g1_policy()->gcs_are_young(), "sanity");
3551 // We also do not allow mixed GCs during marking.
3552 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3554 char verbose_str[128];
3555 sprintf(verbose_str, "GC pause ");
3556 if (g1_policy()->gcs_are_young()) {
3557 strcat(verbose_str, "(young)");
3558 } else {
3559 strcat(verbose_str, "(mixed)");
3560 }
3561 if (g1_policy()->during_initial_mark_pause()) {
3562 strcat(verbose_str, " (initial-mark)");
3563 // We are about to start a marking cycle, so we increment the
3564 // full collection counter.
3565 increment_total_full_collections();
3566 }
3568 // if PrintGCDetails is on, we'll print long statistics information
3569 // in the collector policy code, so let's not print this as the output
3570 // is messy if we do.
3571 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3572 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3573 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3575 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3576 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3578 // If the secondary_free_list is not empty, append it to the
3579 // free_list. No need to wait for the cleanup operation to finish;
3580 // the region allocation code will check the secondary_free_list
3581 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3582 // set, skip this step so that the region allocation code has to
3583 // get entries from the secondary_free_list.
3584 if (!G1StressConcRegionFreeing) {
3585 append_secondary_free_list_if_not_empty_with_lock();
3586 }
3588 assert(check_young_list_well_formed(),
3589 "young list should be well formed");
3591 // Don't dynamically change the number of GC threads this early. A value of
3592 // 0 is used to indicate serial work. When parallel work is done,
3593 // it will be set.
3595 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3596 IsGCActiveMark x;
3598 gc_prologue(false);
3599 increment_total_collections(false /* full gc */);
3600 increment_gc_time_stamp();
3602 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3603 HandleMark hm; // Discard invalid handles created during verification
3604 gclog_or_tty->print(" VerifyBeforeGC:");
3605 prepare_for_verify();
3606 Universe::verify(/* allow dirty */ false,
3607 /* silent */ false,
3608 /* option */ VerifyOption_G1UsePrevMarking);
3610 }
3612 COMPILER2_PRESENT(DerivedPointerTable::clear());
3614 // Please see comment in g1CollectedHeap.hpp and
3615 // G1CollectedHeap::ref_processing_init() to see how
3616 // reference processing currently works in G1.
3618 // Enable discovery in the STW reference processor
3619 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3620 true /*verify_no_refs*/);
3622 {
3623 // We want to temporarily turn off discovery by the
3624 // CM ref processor, if necessary, and turn it back on
3625 // on again later if we do. Using a scoped
3626 // NoRefDiscovery object will do this.
3627 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3629 // Forget the current alloc region (we might even choose it to be part
3630 // of the collection set!).
3631 release_mutator_alloc_region();
3633 // We should call this after we retire the mutator alloc
3634 // region(s) so that all the ALLOC / RETIRE events are generated
3635 // before the start GC event.
3636 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3638 // The elapsed time induced by the start time below deliberately elides
3639 // the possible verification above.
3640 double start_time_sec = os::elapsedTime();
3641 size_t start_used_bytes = used();
3643 #if YOUNG_LIST_VERBOSE
3644 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3645 _young_list->print();
3646 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3647 #endif // YOUNG_LIST_VERBOSE
3649 g1_policy()->record_collection_pause_start(start_time_sec,
3650 start_used_bytes);
3652 #if YOUNG_LIST_VERBOSE
3653 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3654 _young_list->print();
3655 #endif // YOUNG_LIST_VERBOSE
3657 if (g1_policy()->during_initial_mark_pause()) {
3658 concurrent_mark()->checkpointRootsInitialPre();
3659 }
3660 perm_gen()->save_marks();
3662 // We must do this before any possible evacuation that should propagate
3663 // marks.
3664 if (mark_in_progress()) {
3665 double start_time_sec = os::elapsedTime();
3667 _cm->drainAllSATBBuffers();
3668 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3669 g1_policy()->record_satb_drain_time(finish_mark_ms);
3670 }
3671 // Record the number of elements currently on the mark stack, so we
3672 // only iterate over these. (Since evacuation may add to the mark
3673 // stack, doing more exposes race conditions.) If no mark is in
3674 // progress, this will be zero.
3675 _cm->set_oops_do_bound();
3677 if (mark_in_progress()) {
3678 concurrent_mark()->newCSet();
3679 }
3681 #if YOUNG_LIST_VERBOSE
3682 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3683 _young_list->print();
3684 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3685 #endif // YOUNG_LIST_VERBOSE
3687 g1_policy()->choose_collection_set(target_pause_time_ms);
3689 if (_hr_printer.is_active()) {
3690 HeapRegion* hr = g1_policy()->collection_set();
3691 while (hr != NULL) {
3692 G1HRPrinter::RegionType type;
3693 if (!hr->is_young()) {
3694 type = G1HRPrinter::Old;
3695 } else if (hr->is_survivor()) {
3696 type = G1HRPrinter::Survivor;
3697 } else {
3698 type = G1HRPrinter::Eden;
3699 }
3700 _hr_printer.cset(hr);
3701 hr = hr->next_in_collection_set();
3702 }
3703 }
3705 // We have chosen the complete collection set. If marking is
3706 // active then, we clear the region fields of any of the
3707 // concurrent marking tasks whose region fields point into
3708 // the collection set as these values will become stale. This
3709 // will cause the owning marking threads to claim a new region
3710 // when marking restarts.
3711 if (mark_in_progress()) {
3712 concurrent_mark()->reset_active_task_region_fields_in_cset();
3713 }
3715 #ifdef ASSERT
3716 VerifyCSetClosure cl;
3717 collection_set_iterate(&cl);
3718 #endif // ASSERT
3720 setup_surviving_young_words();
3722 // Initialize the GC alloc regions.
3723 init_gc_alloc_regions();
3725 // Actually do the work...
3726 evacuate_collection_set();
3728 free_collection_set(g1_policy()->collection_set());
3729 g1_policy()->clear_collection_set();
3731 cleanup_surviving_young_words();
3733 // Start a new incremental collection set for the next pause.
3734 g1_policy()->start_incremental_cset_building();
3736 // Clear the _cset_fast_test bitmap in anticipation of adding
3737 // regions to the incremental collection set for the next
3738 // evacuation pause.
3739 clear_cset_fast_test();
3741 _young_list->reset_sampled_info();
3743 // Don't check the whole heap at this point as the
3744 // GC alloc regions from this pause have been tagged
3745 // as survivors and moved on to the survivor list.
3746 // Survivor regions will fail the !is_young() check.
3747 assert(check_young_list_empty(false /* check_heap */),
3748 "young list should be empty");
3750 #if YOUNG_LIST_VERBOSE
3751 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3752 _young_list->print();
3753 #endif // YOUNG_LIST_VERBOSE
3755 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3756 _young_list->first_survivor_region(),
3757 _young_list->last_survivor_region());
3759 _young_list->reset_auxilary_lists();
3761 if (evacuation_failed()) {
3762 _summary_bytes_used = recalculate_used();
3763 } else {
3764 // The "used" of the the collection set have already been subtracted
3765 // when they were freed. Add in the bytes evacuated.
3766 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3767 }
3769 if (g1_policy()->during_initial_mark_pause()) {
3770 concurrent_mark()->checkpointRootsInitialPost();
3771 set_marking_started();
3772 // CAUTION: after the doConcurrentMark() call below,
3773 // the concurrent marking thread(s) could be running
3774 // concurrently with us. Make sure that anything after
3775 // this point does not assume that we are the only GC thread
3776 // running. Note: of course, the actual marking work will
3777 // not start until the safepoint itself is released in
3778 // ConcurrentGCThread::safepoint_desynchronize().
3779 doConcurrentMark();
3780 }
3782 allocate_dummy_regions();
3784 #if YOUNG_LIST_VERBOSE
3785 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3786 _young_list->print();
3787 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3788 #endif // YOUNG_LIST_VERBOSE
3790 init_mutator_alloc_region();
3792 {
3793 size_t expand_bytes = g1_policy()->expansion_amount();
3794 if (expand_bytes > 0) {
3795 size_t bytes_before = capacity();
3796 // No need for an ergo verbose message here,
3797 // expansion_amount() does this when it returns a value > 0.
3798 if (!expand(expand_bytes)) {
3799 // We failed to expand the heap so let's verify that
3800 // committed/uncommitted amount match the backing store
3801 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3802 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3803 }
3804 }
3805 }
3807 double end_time_sec = os::elapsedTime();
3808 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3809 g1_policy()->record_pause_time_ms(pause_time_ms);
3810 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3811 workers()->active_workers() : 1);
3812 g1_policy()->record_collection_pause_end(active_workers);
3814 MemoryService::track_memory_usage();
3816 // In prepare_for_verify() below we'll need to scan the deferred
3817 // update buffers to bring the RSets up-to-date if
3818 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3819 // the update buffers we'll probably need to scan cards on the
3820 // regions we just allocated to (i.e., the GC alloc
3821 // regions). However, during the last GC we called
3822 // set_saved_mark() on all the GC alloc regions, so card
3823 // scanning might skip the [saved_mark_word()...top()] area of
3824 // those regions (i.e., the area we allocated objects into
3825 // during the last GC). But it shouldn't. Given that
3826 // saved_mark_word() is conditional on whether the GC time stamp
3827 // on the region is current or not, by incrementing the GC time
3828 // stamp here we invalidate all the GC time stamps on all the
3829 // regions and saved_mark_word() will simply return top() for
3830 // all the regions. This is a nicer way of ensuring this rather
3831 // than iterating over the regions and fixing them. In fact, the
3832 // GC time stamp increment here also ensures that
3833 // saved_mark_word() will return top() between pauses, i.e.,
3834 // during concurrent refinement. So we don't need the
3835 // is_gc_active() check to decided which top to use when
3836 // scanning cards (see CR 7039627).
3837 increment_gc_time_stamp();
3839 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3840 HandleMark hm; // Discard invalid handles created during verification
3841 gclog_or_tty->print(" VerifyAfterGC:");
3842 prepare_for_verify();
3843 Universe::verify(/* allow dirty */ true,
3844 /* silent */ false,
3845 /* option */ VerifyOption_G1UsePrevMarking);
3846 }
3848 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3849 ref_processor_stw()->verify_no_references_recorded();
3851 // CM reference discovery will be re-enabled if necessary.
3852 }
3854 // We should do this after we potentially expand the heap so
3855 // that all the COMMIT events are generated before the end GC
3856 // event, and after we retire the GC alloc regions so that all
3857 // RETIRE events are generated before the end GC event.
3858 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3860 // We have to do this after we decide whether to expand the heap or not.
3861 g1_policy()->print_heap_transition();
3863 if (mark_in_progress()) {
3864 concurrent_mark()->update_g1_committed();
3865 }
3867 #ifdef TRACESPINNING
3868 ParallelTaskTerminator::print_termination_counts();
3869 #endif
3871 gc_epilogue(false);
3872 }
3874 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3875 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3876 print_tracing_info();
3877 vm_exit(-1);
3878 }
3879 }
3881 _hrs.verify_optional();
3882 verify_region_sets_optional();
3884 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3885 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3887 if (PrintHeapAtGC) {
3888 Universe::print_heap_after_gc();
3889 }
3890 g1mm()->update_sizes();
3892 if (G1SummarizeRSetStats &&
3893 (G1SummarizeRSetStatsPeriod > 0) &&
3894 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3895 g1_rem_set()->print_summary_info();
3896 }
3898 return true;
3899 }
3901 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3902 {
3903 size_t gclab_word_size;
3904 switch (purpose) {
3905 case GCAllocForSurvived:
3906 gclab_word_size = YoungPLABSize;
3907 break;
3908 case GCAllocForTenured:
3909 gclab_word_size = OldPLABSize;
3910 break;
3911 default:
3912 assert(false, "unknown GCAllocPurpose");
3913 gclab_word_size = OldPLABSize;
3914 break;
3915 }
3916 return gclab_word_size;
3917 }
3919 void G1CollectedHeap::init_mutator_alloc_region() {
3920 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3921 _mutator_alloc_region.init();
3922 }
3924 void G1CollectedHeap::release_mutator_alloc_region() {
3925 _mutator_alloc_region.release();
3926 assert(_mutator_alloc_region.get() == NULL, "post-condition");
3927 }
3929 void G1CollectedHeap::init_gc_alloc_regions() {
3930 assert_at_safepoint(true /* should_be_vm_thread */);
3932 _survivor_gc_alloc_region.init();
3933 _old_gc_alloc_region.init();
3934 HeapRegion* retained_region = _retained_old_gc_alloc_region;
3935 _retained_old_gc_alloc_region = NULL;
3937 // We will discard the current GC alloc region if:
3938 // a) it's in the collection set (it can happen!),
3939 // b) it's already full (no point in using it),
3940 // c) it's empty (this means that it was emptied during
3941 // a cleanup and it should be on the free list now), or
3942 // d) it's humongous (this means that it was emptied
3943 // during a cleanup and was added to the free list, but
3944 // has been subseqently used to allocate a humongous
3945 // object that may be less than the region size).
3946 if (retained_region != NULL &&
3947 !retained_region->in_collection_set() &&
3948 !(retained_region->top() == retained_region->end()) &&
3949 !retained_region->is_empty() &&
3950 !retained_region->isHumongous()) {
3951 retained_region->set_saved_mark();
3952 // The retained region was added to the old region set when it was
3953 // retired. We have to remove it now, since we don't allow regions
3954 // we allocate to in the region sets. We'll re-add it later, when
3955 // it's retired again.
3956 _old_set.remove(retained_region);
3957 _old_gc_alloc_region.set(retained_region);
3958 _hr_printer.reuse(retained_region);
3959 }
3960 }
3962 void G1CollectedHeap::release_gc_alloc_regions() {
3963 _survivor_gc_alloc_region.release();
3964 // If we have an old GC alloc region to release, we'll save it in
3965 // _retained_old_gc_alloc_region. If we don't
3966 // _retained_old_gc_alloc_region will become NULL. This is what we
3967 // want either way so no reason to check explicitly for either
3968 // condition.
3969 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
3970 }
3972 void G1CollectedHeap::abandon_gc_alloc_regions() {
3973 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
3974 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
3975 _retained_old_gc_alloc_region = NULL;
3976 }
3978 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3979 _drain_in_progress = false;
3980 set_evac_failure_closure(cl);
3981 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3982 }
3984 void G1CollectedHeap::finalize_for_evac_failure() {
3985 assert(_evac_failure_scan_stack != NULL &&
3986 _evac_failure_scan_stack->length() == 0,
3987 "Postcondition");
3988 assert(!_drain_in_progress, "Postcondition");
3989 delete _evac_failure_scan_stack;
3990 _evac_failure_scan_stack = NULL;
3991 }
3993 void G1CollectedHeap::remove_self_forwarding_pointers() {
3994 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
3995 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3997 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
3999 if (G1CollectedHeap::use_parallel_gc_threads()) {
4000 set_par_threads();
4001 workers()->run_task(&rsfp_task);
4002 set_par_threads(0);
4003 } else {
4004 rsfp_task.work(0);
4005 }
4007 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4009 // Reset the claim values in the regions in the collection set.
4010 reset_cset_heap_region_claim_values();
4012 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4013 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4015 // Now restore saved marks, if any.
4016 if (_objs_with_preserved_marks != NULL) {
4017 assert(_preserved_marks_of_objs != NULL, "Both or none.");
4018 guarantee(_objs_with_preserved_marks->length() ==
4019 _preserved_marks_of_objs->length(), "Both or none.");
4020 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
4021 oop obj = _objs_with_preserved_marks->at(i);
4022 markOop m = _preserved_marks_of_objs->at(i);
4023 obj->set_mark(m);
4024 }
4026 // Delete the preserved marks growable arrays (allocated on the C heap).
4027 delete _objs_with_preserved_marks;
4028 delete _preserved_marks_of_objs;
4029 _objs_with_preserved_marks = NULL;
4030 _preserved_marks_of_objs = NULL;
4031 }
4032 }
4034 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4035 _evac_failure_scan_stack->push(obj);
4036 }
4038 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4039 assert(_evac_failure_scan_stack != NULL, "precondition");
4041 while (_evac_failure_scan_stack->length() > 0) {
4042 oop obj = _evac_failure_scan_stack->pop();
4043 _evac_failure_closure->set_region(heap_region_containing(obj));
4044 obj->oop_iterate_backwards(_evac_failure_closure);
4045 }
4046 }
4048 oop
4049 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4050 oop old,
4051 bool should_mark_root) {
4052 assert(obj_in_cs(old),
4053 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4054 (HeapWord*) old));
4055 markOop m = old->mark();
4056 oop forward_ptr = old->forward_to_atomic(old);
4057 if (forward_ptr == NULL) {
4058 // Forward-to-self succeeded.
4060 // should_mark_root will be true when this routine is called
4061 // from a root scanning closure during an initial mark pause.
4062 // In this case the thread that succeeds in self-forwarding the
4063 // object is also responsible for marking the object.
4064 if (should_mark_root) {
4065 assert(!oopDesc::is_null(old), "shouldn't be");
4066 _cm->grayRoot(old);
4067 }
4069 if (_evac_failure_closure != cl) {
4070 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4071 assert(!_drain_in_progress,
4072 "Should only be true while someone holds the lock.");
4073 // Set the global evac-failure closure to the current thread's.
4074 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4075 set_evac_failure_closure(cl);
4076 // Now do the common part.
4077 handle_evacuation_failure_common(old, m);
4078 // Reset to NULL.
4079 set_evac_failure_closure(NULL);
4080 } else {
4081 // The lock is already held, and this is recursive.
4082 assert(_drain_in_progress, "This should only be the recursive case.");
4083 handle_evacuation_failure_common(old, m);
4084 }
4085 return old;
4086 } else {
4087 // Forward-to-self failed. Either someone else managed to allocate
4088 // space for this object (old != forward_ptr) or they beat us in
4089 // self-forwarding it (old == forward_ptr).
4090 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4091 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4092 "should not be in the CSet",
4093 (HeapWord*) old, (HeapWord*) forward_ptr));
4094 return forward_ptr;
4095 }
4096 }
4098 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4099 set_evacuation_failed(true);
4101 preserve_mark_if_necessary(old, m);
4103 HeapRegion* r = heap_region_containing(old);
4104 if (!r->evacuation_failed()) {
4105 r->set_evacuation_failed(true);
4106 _hr_printer.evac_failure(r);
4107 }
4109 push_on_evac_failure_scan_stack(old);
4111 if (!_drain_in_progress) {
4112 // prevent recursion in copy_to_survivor_space()
4113 _drain_in_progress = true;
4114 drain_evac_failure_scan_stack();
4115 _drain_in_progress = false;
4116 }
4117 }
4119 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4120 assert(evacuation_failed(), "Oversaving!");
4121 // We want to call the "for_promotion_failure" version only in the
4122 // case of a promotion failure.
4123 if (m->must_be_preserved_for_promotion_failure(obj)) {
4124 if (_objs_with_preserved_marks == NULL) {
4125 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4126 _objs_with_preserved_marks =
4127 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4128 _preserved_marks_of_objs =
4129 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4130 }
4131 _objs_with_preserved_marks->push(obj);
4132 _preserved_marks_of_objs->push(m);
4133 }
4134 }
4136 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4137 size_t word_size) {
4138 if (purpose == GCAllocForSurvived) {
4139 HeapWord* result = survivor_attempt_allocation(word_size);
4140 if (result != NULL) {
4141 return result;
4142 } else {
4143 // Let's try to allocate in the old gen in case we can fit the
4144 // object there.
4145 return old_attempt_allocation(word_size);
4146 }
4147 } else {
4148 assert(purpose == GCAllocForTenured, "sanity");
4149 HeapWord* result = old_attempt_allocation(word_size);
4150 if (result != NULL) {
4151 return result;
4152 } else {
4153 // Let's try to allocate in the survivors in case we can fit the
4154 // object there.
4155 return survivor_attempt_allocation(word_size);
4156 }
4157 }
4159 ShouldNotReachHere();
4160 // Trying to keep some compilers happy.
4161 return NULL;
4162 }
4164 #ifndef PRODUCT
4165 bool GCLabBitMapClosure::do_bit(size_t offset) {
4166 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4167 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4168 return true;
4169 }
4170 #endif // PRODUCT
4172 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4173 ParGCAllocBuffer(gclab_word_size),
4174 _should_mark_objects(false),
4175 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
4176 _retired(false)
4177 {
4178 //_should_mark_objects is set to true when G1ParCopyHelper needs to
4179 // mark the forwarded location of an evacuated object.
4180 // We set _should_mark_objects to true if marking is active, i.e. when we
4181 // need to propagate a mark, or during an initial mark pause, i.e. when we
4182 // need to mark objects immediately reachable by the roots.
4183 if (G1CollectedHeap::heap()->mark_in_progress() ||
4184 G1CollectedHeap::heap()->g1_policy()->during_initial_mark_pause()) {
4185 _should_mark_objects = true;
4186 }
4187 }
4189 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4190 : _g1h(g1h),
4191 _refs(g1h->task_queue(queue_num)),
4192 _dcq(&g1h->dirty_card_queue_set()),
4193 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4194 _g1_rem(g1h->g1_rem_set()),
4195 _hash_seed(17), _queue_num(queue_num),
4196 _term_attempts(0),
4197 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4198 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4199 _age_table(false),
4200 _strong_roots_time(0), _term_time(0),
4201 _alloc_buffer_waste(0), _undo_waste(0)
4202 {
4203 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4204 // we "sacrifice" entry 0 to keep track of surviving bytes for
4205 // non-young regions (where the age is -1)
4206 // We also add a few elements at the beginning and at the end in
4207 // an attempt to eliminate cache contention
4208 size_t real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4209 size_t array_length = PADDING_ELEM_NUM +
4210 real_length +
4211 PADDING_ELEM_NUM;
4212 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4213 if (_surviving_young_words_base == NULL)
4214 vm_exit_out_of_memory(array_length * sizeof(size_t),
4215 "Not enough space for young surv histo.");
4216 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4217 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4219 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4220 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4222 _start = os::elapsedTime();
4223 }
4225 void
4226 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4227 {
4228 st->print_raw_cr("GC Termination Stats");
4229 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4230 " ------waste (KiB)------");
4231 st->print_raw_cr("thr ms ms % ms % attempts"
4232 " total alloc undo");
4233 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4234 " ------- ------- -------");
4235 }
4237 void
4238 G1ParScanThreadState::print_termination_stats(int i,
4239 outputStream* const st) const
4240 {
4241 const double elapsed_ms = elapsed_time() * 1000.0;
4242 const double s_roots_ms = strong_roots_time() * 1000.0;
4243 const double term_ms = term_time() * 1000.0;
4244 st->print_cr("%3d %9.2f %9.2f %6.2f "
4245 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4246 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4247 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4248 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4249 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4250 alloc_buffer_waste() * HeapWordSize / K,
4251 undo_waste() * HeapWordSize / K);
4252 }
4254 #ifdef ASSERT
4255 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4256 assert(ref != NULL, "invariant");
4257 assert(UseCompressedOops, "sanity");
4258 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4259 oop p = oopDesc::load_decode_heap_oop(ref);
4260 assert(_g1h->is_in_g1_reserved(p),
4261 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4262 return true;
4263 }
4265 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4266 assert(ref != NULL, "invariant");
4267 if (has_partial_array_mask(ref)) {
4268 // Must be in the collection set--it's already been copied.
4269 oop p = clear_partial_array_mask(ref);
4270 assert(_g1h->obj_in_cs(p),
4271 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4272 } else {
4273 oop p = oopDesc::load_decode_heap_oop(ref);
4274 assert(_g1h->is_in_g1_reserved(p),
4275 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4276 }
4277 return true;
4278 }
4280 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4281 if (ref.is_narrow()) {
4282 return verify_ref((narrowOop*) ref);
4283 } else {
4284 return verify_ref((oop*) ref);
4285 }
4286 }
4287 #endif // ASSERT
4289 void G1ParScanThreadState::trim_queue() {
4290 assert(_evac_cl != NULL, "not set");
4291 assert(_evac_failure_cl != NULL, "not set");
4292 assert(_partial_scan_cl != NULL, "not set");
4294 StarTask ref;
4295 do {
4296 // Drain the overflow stack first, so other threads can steal.
4297 while (refs()->pop_overflow(ref)) {
4298 deal_with_reference(ref);
4299 }
4301 while (refs()->pop_local(ref)) {
4302 deal_with_reference(ref);
4303 }
4304 } while (!refs()->is_empty());
4305 }
4307 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4308 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4309 _par_scan_state(par_scan_state),
4310 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4311 _mark_in_progress(_g1->mark_in_progress()) { }
4313 template <class T> void G1ParCopyHelper::mark_object(T* p) {
4314 // This is called from do_oop_work for objects that are not
4315 // in the collection set. Objects in the collection set
4316 // are marked after they have been evacuated.
4318 T heap_oop = oopDesc::load_heap_oop(p);
4319 if (!oopDesc::is_null(heap_oop)) {
4320 oop obj = oopDesc::decode_heap_oop(heap_oop);
4321 HeapWord* addr = (HeapWord*)obj;
4322 if (_g1->is_in_g1_reserved(addr)) {
4323 _cm->grayRoot(oop(addr));
4324 }
4325 }
4326 }
4328 oop G1ParCopyHelper::copy_to_survivor_space(oop old, bool should_mark_root,
4329 bool should_mark_copy) {
4330 size_t word_sz = old->size();
4331 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4332 // +1 to make the -1 indexes valid...
4333 int young_index = from_region->young_index_in_cset()+1;
4334 assert( (from_region->is_young() && young_index > 0) ||
4335 (!from_region->is_young() && young_index == 0), "invariant" );
4336 G1CollectorPolicy* g1p = _g1->g1_policy();
4337 markOop m = old->mark();
4338 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4339 : m->age();
4340 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4341 word_sz);
4342 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4343 oop obj = oop(obj_ptr);
4345 if (obj_ptr == NULL) {
4346 // This will either forward-to-self, or detect that someone else has
4347 // installed a forwarding pointer.
4348 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4349 return _g1->handle_evacuation_failure_par(cl, old, should_mark_root);
4350 }
4352 // We're going to allocate linearly, so might as well prefetch ahead.
4353 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4355 oop forward_ptr = old->forward_to_atomic(obj);
4356 if (forward_ptr == NULL) {
4357 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4358 if (g1p->track_object_age(alloc_purpose)) {
4359 // We could simply do obj->incr_age(). However, this causes a
4360 // performance issue. obj->incr_age() will first check whether
4361 // the object has a displaced mark by checking its mark word;
4362 // getting the mark word from the new location of the object
4363 // stalls. So, given that we already have the mark word and we
4364 // are about to install it anyway, it's better to increase the
4365 // age on the mark word, when the object does not have a
4366 // displaced mark word. We're not expecting many objects to have
4367 // a displaced marked word, so that case is not optimized
4368 // further (it could be...) and we simply call obj->incr_age().
4370 if (m->has_displaced_mark_helper()) {
4371 // in this case, we have to install the mark word first,
4372 // otherwise obj looks to be forwarded (the old mark word,
4373 // which contains the forward pointer, was copied)
4374 obj->set_mark(m);
4375 obj->incr_age();
4376 } else {
4377 m = m->incr_age();
4378 obj->set_mark(m);
4379 }
4380 _par_scan_state->age_table()->add(obj, word_sz);
4381 } else {
4382 obj->set_mark(m);
4383 }
4385 // Mark the evacuated object or propagate "next" mark bit
4386 if (should_mark_copy) {
4387 if (!use_local_bitmaps ||
4388 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4389 // if we couldn't mark it on the local bitmap (this happens when
4390 // the object was not allocated in the GCLab), we have to bite
4391 // the bullet and do the standard parallel mark
4392 _cm->markAndGrayObjectIfNecessary(obj);
4393 }
4395 if (_g1->isMarkedNext(old)) {
4396 // Unmark the object's old location so that marking
4397 // doesn't think the old object is alive.
4398 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4399 }
4400 }
4402 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4403 surv_young_words[young_index] += word_sz;
4405 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4406 // We keep track of the next start index in the length field of
4407 // the to-space object. The actual length can be found in the
4408 // length field of the from-space object.
4409 arrayOop(obj)->set_length(0);
4410 oop* old_p = set_partial_array_mask(old);
4411 _par_scan_state->push_on_queue(old_p);
4412 } else {
4413 // No point in using the slower heap_region_containing() method,
4414 // given that we know obj is in the heap.
4415 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4416 obj->oop_iterate_backwards(_scanner);
4417 }
4418 } else {
4419 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4420 obj = forward_ptr;
4421 }
4422 return obj;
4423 }
4425 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4426 template <class T>
4427 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4428 ::do_oop_work(T* p) {
4429 oop obj = oopDesc::load_decode_heap_oop(p);
4430 assert(barrier != G1BarrierRS || obj != NULL,
4431 "Precondition: G1BarrierRS implies obj is nonNull");
4433 // Marking:
4434 // If the object is in the collection set, then the thread
4435 // that copies the object should mark, or propagate the
4436 // mark to, the evacuated object.
4437 // If the object is not in the collection set then we
4438 // should call the mark_object() method depending on the
4439 // value of the template parameter do_mark_object (which will
4440 // be true for root scanning closures during an initial mark
4441 // pause).
4442 // The mark_object() method first checks whether the object
4443 // is marked and, if not, attempts to mark the object.
4445 // here the null check is implicit in the cset_fast_test() test
4446 if (_g1->in_cset_fast_test(obj)) {
4447 if (obj->is_forwarded()) {
4448 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4449 // If we are a root scanning closure during an initial
4450 // mark pause (i.e. do_mark_object will be true) then
4451 // we also need to handle marking of roots in the
4452 // event of an evacuation failure. In the event of an
4453 // evacuation failure, the object is forwarded to itself
4454 // and not copied. For root-scanning closures, the
4455 // object would be marked after a successful self-forward
4456 // but an object could be pointed to by both a root and non
4457 // root location and be self-forwarded by a non-root-scanning
4458 // closure. Therefore we also have to attempt to mark the
4459 // self-forwarded root object here.
4460 if (do_mark_object && obj->forwardee() == obj) {
4461 mark_object(p);
4462 }
4463 } else {
4464 // During an initial mark pause, objects that are pointed to
4465 // by the roots need to be marked - even in the event of an
4466 // evacuation failure. We pass the template parameter
4467 // do_mark_object (which is true for root scanning closures
4468 // during an initial mark pause) to copy_to_survivor_space
4469 // which will pass it on to the evacuation failure handling
4470 // code. The thread that successfully self-forwards a root
4471 // object to itself is responsible for marking the object.
4472 bool should_mark_root = do_mark_object;
4474 // We need to mark the copied object if we're a root scanning
4475 // closure during an initial mark pause (i.e. do_mark_object
4476 // will be true), or the object is already marked and we need
4477 // to propagate the mark to the evacuated copy.
4478 bool should_mark_copy = do_mark_object ||
4479 _during_initial_mark ||
4480 (_mark_in_progress && !_g1->is_obj_ill(obj));
4482 oop copy_oop = copy_to_survivor_space(obj, should_mark_root,
4483 should_mark_copy);
4484 oopDesc::encode_store_heap_oop(p, copy_oop);
4485 }
4486 // When scanning the RS, we only care about objs in CS.
4487 if (barrier == G1BarrierRS) {
4488 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4489 }
4490 } else {
4491 // The object is not in collection set. If we're a root scanning
4492 // closure during an initial mark pause (i.e. do_mark_object will
4493 // be true) then attempt to mark the object.
4494 if (do_mark_object) {
4495 mark_object(p);
4496 }
4497 }
4499 if (barrier == G1BarrierEvac && obj != NULL) {
4500 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4501 }
4503 if (do_gen_barrier && obj != NULL) {
4504 par_do_barrier(p);
4505 }
4506 }
4508 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4509 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4511 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4512 assert(has_partial_array_mask(p), "invariant");
4513 oop from_obj = clear_partial_array_mask(p);
4515 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4516 assert(from_obj->is_objArray(), "must be obj array");
4517 objArrayOop from_obj_array = objArrayOop(from_obj);
4518 // The from-space object contains the real length.
4519 int length = from_obj_array->length();
4521 assert(from_obj->is_forwarded(), "must be forwarded");
4522 oop to_obj = from_obj->forwardee();
4523 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4524 objArrayOop to_obj_array = objArrayOop(to_obj);
4525 // We keep track of the next start index in the length field of the
4526 // to-space object.
4527 int next_index = to_obj_array->length();
4528 assert(0 <= next_index && next_index < length,
4529 err_msg("invariant, next index: %d, length: %d", next_index, length));
4531 int start = next_index;
4532 int end = length;
4533 int remainder = end - start;
4534 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4535 if (remainder > 2 * ParGCArrayScanChunk) {
4536 end = start + ParGCArrayScanChunk;
4537 to_obj_array->set_length(end);
4538 // Push the remainder before we process the range in case another
4539 // worker has run out of things to do and can steal it.
4540 oop* from_obj_p = set_partial_array_mask(from_obj);
4541 _par_scan_state->push_on_queue(from_obj_p);
4542 } else {
4543 assert(length == end, "sanity");
4544 // We'll process the final range for this object. Restore the length
4545 // so that the heap remains parsable in case of evacuation failure.
4546 to_obj_array->set_length(end);
4547 }
4548 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4549 // Process indexes [start,end). It will also process the header
4550 // along with the first chunk (i.e., the chunk with start == 0).
4551 // Note that at this point the length field of to_obj_array is not
4552 // correct given that we are using it to keep track of the next
4553 // start index. oop_iterate_range() (thankfully!) ignores the length
4554 // field and only relies on the start / end parameters. It does
4555 // however return the size of the object which will be incorrect. So
4556 // we have to ignore it even if we wanted to use it.
4557 to_obj_array->oop_iterate_range(&_scanner, start, end);
4558 }
4560 class G1ParEvacuateFollowersClosure : public VoidClosure {
4561 protected:
4562 G1CollectedHeap* _g1h;
4563 G1ParScanThreadState* _par_scan_state;
4564 RefToScanQueueSet* _queues;
4565 ParallelTaskTerminator* _terminator;
4567 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4568 RefToScanQueueSet* queues() { return _queues; }
4569 ParallelTaskTerminator* terminator() { return _terminator; }
4571 public:
4572 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4573 G1ParScanThreadState* par_scan_state,
4574 RefToScanQueueSet* queues,
4575 ParallelTaskTerminator* terminator)
4576 : _g1h(g1h), _par_scan_state(par_scan_state),
4577 _queues(queues), _terminator(terminator) {}
4579 void do_void();
4581 private:
4582 inline bool offer_termination();
4583 };
4585 bool G1ParEvacuateFollowersClosure::offer_termination() {
4586 G1ParScanThreadState* const pss = par_scan_state();
4587 pss->start_term_time();
4588 const bool res = terminator()->offer_termination();
4589 pss->end_term_time();
4590 return res;
4591 }
4593 void G1ParEvacuateFollowersClosure::do_void() {
4594 StarTask stolen_task;
4595 G1ParScanThreadState* const pss = par_scan_state();
4596 pss->trim_queue();
4598 do {
4599 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4600 assert(pss->verify_task(stolen_task), "sanity");
4601 if (stolen_task.is_narrow()) {
4602 pss->deal_with_reference((narrowOop*) stolen_task);
4603 } else {
4604 pss->deal_with_reference((oop*) stolen_task);
4605 }
4607 // We've just processed a reference and we might have made
4608 // available new entries on the queues. So we have to make sure
4609 // we drain the queues as necessary.
4610 pss->trim_queue();
4611 }
4612 } while (!offer_termination());
4614 pss->retire_alloc_buffers();
4615 }
4617 class G1ParTask : public AbstractGangTask {
4618 protected:
4619 G1CollectedHeap* _g1h;
4620 RefToScanQueueSet *_queues;
4621 ParallelTaskTerminator _terminator;
4622 uint _n_workers;
4624 Mutex _stats_lock;
4625 Mutex* stats_lock() { return &_stats_lock; }
4627 size_t getNCards() {
4628 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4629 / G1BlockOffsetSharedArray::N_bytes;
4630 }
4632 public:
4633 G1ParTask(G1CollectedHeap* g1h,
4634 RefToScanQueueSet *task_queues)
4635 : AbstractGangTask("G1 collection"),
4636 _g1h(g1h),
4637 _queues(task_queues),
4638 _terminator(0, _queues),
4639 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4640 {}
4642 RefToScanQueueSet* queues() { return _queues; }
4644 RefToScanQueue *work_queue(int i) {
4645 return queues()->queue(i);
4646 }
4648 ParallelTaskTerminator* terminator() { return &_terminator; }
4650 virtual void set_for_termination(int active_workers) {
4651 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4652 // in the young space (_par_seq_tasks) in the G1 heap
4653 // for SequentialSubTasksDone.
4654 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4655 // both of which need setting by set_n_termination().
4656 _g1h->SharedHeap::set_n_termination(active_workers);
4657 _g1h->set_n_termination(active_workers);
4658 terminator()->reset_for_reuse(active_workers);
4659 _n_workers = active_workers;
4660 }
4662 void work(uint worker_id) {
4663 if (worker_id >= _n_workers) return; // no work needed this round
4665 double start_time_ms = os::elapsedTime() * 1000.0;
4666 _g1h->g1_policy()->record_gc_worker_start_time(worker_id, start_time_ms);
4668 ResourceMark rm;
4669 HandleMark hm;
4671 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4673 G1ParScanThreadState pss(_g1h, worker_id);
4674 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4675 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4676 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4678 pss.set_evac_closure(&scan_evac_cl);
4679 pss.set_evac_failure_closure(&evac_failure_cl);
4680 pss.set_partial_scan_closure(&partial_scan_cl);
4682 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4683 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp);
4685 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4686 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp);
4688 OopClosure* scan_root_cl = &only_scan_root_cl;
4689 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl;
4691 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4692 // We also need to mark copied objects.
4693 scan_root_cl = &scan_mark_root_cl;
4694 scan_perm_cl = &scan_mark_perm_cl;
4695 }
4697 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4699 pss.start_strong_roots();
4700 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4701 SharedHeap::SO_AllClasses,
4702 scan_root_cl,
4703 &push_heap_rs_cl,
4704 scan_perm_cl,
4705 worker_id);
4706 pss.end_strong_roots();
4708 {
4709 double start = os::elapsedTime();
4710 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4711 evac.do_void();
4712 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4713 double term_ms = pss.term_time()*1000.0;
4714 _g1h->g1_policy()->record_obj_copy_time(worker_id, elapsed_ms-term_ms);
4715 _g1h->g1_policy()->record_termination(worker_id, term_ms, pss.term_attempts());
4716 }
4717 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4718 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4720 // Clean up any par-expanded rem sets.
4721 HeapRegionRemSet::par_cleanup();
4723 if (ParallelGCVerbose) {
4724 MutexLocker x(stats_lock());
4725 pss.print_termination_stats(worker_id);
4726 }
4728 assert(pss.refs()->is_empty(), "should be empty");
4729 double end_time_ms = os::elapsedTime() * 1000.0;
4730 _g1h->g1_policy()->record_gc_worker_end_time(worker_id, end_time_ms);
4731 }
4732 };
4734 // *** Common G1 Evacuation Stuff
4736 // This method is run in a GC worker.
4738 void
4739 G1CollectedHeap::
4740 g1_process_strong_roots(bool collecting_perm_gen,
4741 SharedHeap::ScanningOption so,
4742 OopClosure* scan_non_heap_roots,
4743 OopsInHeapRegionClosure* scan_rs,
4744 OopsInGenClosure* scan_perm,
4745 int worker_i) {
4747 // First scan the strong roots, including the perm gen.
4748 double ext_roots_start = os::elapsedTime();
4749 double closure_app_time_sec = 0.0;
4751 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4752 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4753 buf_scan_perm.set_generation(perm_gen());
4755 // Walk the code cache w/o buffering, because StarTask cannot handle
4756 // unaligned oop locations.
4757 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4759 process_strong_roots(false, // no scoping; this is parallel code
4760 collecting_perm_gen, so,
4761 &buf_scan_non_heap_roots,
4762 &eager_scan_code_roots,
4763 &buf_scan_perm);
4765 // Now the CM ref_processor roots.
4766 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4767 // We need to treat the discovered reference lists of the
4768 // concurrent mark ref processor as roots and keep entries
4769 // (which are added by the marking threads) on them live
4770 // until they can be processed at the end of marking.
4771 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4772 }
4774 // Finish up any enqueued closure apps (attributed as object copy time).
4775 buf_scan_non_heap_roots.done();
4776 buf_scan_perm.done();
4778 double ext_roots_end = os::elapsedTime();
4780 g1_policy()->reset_obj_copy_time(worker_i);
4781 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4782 buf_scan_non_heap_roots.closure_app_seconds();
4783 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4785 double ext_root_time_ms =
4786 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4788 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4790 // Scan strong roots in mark stack.
4791 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4792 concurrent_mark()->oops_do(scan_non_heap_roots);
4793 }
4794 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4795 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4797 // Now scan the complement of the collection set.
4798 if (scan_rs != NULL) {
4799 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4800 }
4802 _process_strong_tasks->all_tasks_completed();
4803 }
4805 void
4806 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4807 OopClosure* non_root_closure) {
4808 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4809 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4810 }
4812 // Weak Reference Processing support
4814 // An always "is_alive" closure that is used to preserve referents.
4815 // If the object is non-null then it's alive. Used in the preservation
4816 // of referent objects that are pointed to by reference objects
4817 // discovered by the CM ref processor.
4818 class G1AlwaysAliveClosure: public BoolObjectClosure {
4819 G1CollectedHeap* _g1;
4820 public:
4821 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4822 void do_object(oop p) { assert(false, "Do not call."); }
4823 bool do_object_b(oop p) {
4824 if (p != NULL) {
4825 return true;
4826 }
4827 return false;
4828 }
4829 };
4831 bool G1STWIsAliveClosure::do_object_b(oop p) {
4832 // An object is reachable if it is outside the collection set,
4833 // or is inside and copied.
4834 return !_g1->obj_in_cs(p) || p->is_forwarded();
4835 }
4837 // Non Copying Keep Alive closure
4838 class G1KeepAliveClosure: public OopClosure {
4839 G1CollectedHeap* _g1;
4840 public:
4841 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4842 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4843 void do_oop( oop* p) {
4844 oop obj = *p;
4846 if (_g1->obj_in_cs(obj)) {
4847 assert( obj->is_forwarded(), "invariant" );
4848 *p = obj->forwardee();
4849 }
4850 }
4851 };
4853 // Copying Keep Alive closure - can be called from both
4854 // serial and parallel code as long as different worker
4855 // threads utilize different G1ParScanThreadState instances
4856 // and different queues.
4858 class G1CopyingKeepAliveClosure: public OopClosure {
4859 G1CollectedHeap* _g1h;
4860 OopClosure* _copy_non_heap_obj_cl;
4861 OopsInHeapRegionClosure* _copy_perm_obj_cl;
4862 G1ParScanThreadState* _par_scan_state;
4864 public:
4865 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4866 OopClosure* non_heap_obj_cl,
4867 OopsInHeapRegionClosure* perm_obj_cl,
4868 G1ParScanThreadState* pss):
4869 _g1h(g1h),
4870 _copy_non_heap_obj_cl(non_heap_obj_cl),
4871 _copy_perm_obj_cl(perm_obj_cl),
4872 _par_scan_state(pss)
4873 {}
4875 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4876 virtual void do_oop( oop* p) { do_oop_work(p); }
4878 template <class T> void do_oop_work(T* p) {
4879 oop obj = oopDesc::load_decode_heap_oop(p);
4881 if (_g1h->obj_in_cs(obj)) {
4882 // If the referent object has been forwarded (either copied
4883 // to a new location or to itself in the event of an
4884 // evacuation failure) then we need to update the reference
4885 // field and, if both reference and referent are in the G1
4886 // heap, update the RSet for the referent.
4887 //
4888 // If the referent has not been forwarded then we have to keep
4889 // it alive by policy. Therefore we have copy the referent.
4890 //
4891 // If the reference field is in the G1 heap then we can push
4892 // on the PSS queue. When the queue is drained (after each
4893 // phase of reference processing) the object and it's followers
4894 // will be copied, the reference field set to point to the
4895 // new location, and the RSet updated. Otherwise we need to
4896 // use the the non-heap or perm closures directly to copy
4897 // the refernt object and update the pointer, while avoiding
4898 // updating the RSet.
4900 if (_g1h->is_in_g1_reserved(p)) {
4901 _par_scan_state->push_on_queue(p);
4902 } else {
4903 // The reference field is not in the G1 heap.
4904 if (_g1h->perm_gen()->is_in(p)) {
4905 _copy_perm_obj_cl->do_oop(p);
4906 } else {
4907 _copy_non_heap_obj_cl->do_oop(p);
4908 }
4909 }
4910 }
4911 }
4912 };
4914 // Serial drain queue closure. Called as the 'complete_gc'
4915 // closure for each discovered list in some of the
4916 // reference processing phases.
4918 class G1STWDrainQueueClosure: public VoidClosure {
4919 protected:
4920 G1CollectedHeap* _g1h;
4921 G1ParScanThreadState* _par_scan_state;
4923 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4925 public:
4926 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4927 _g1h(g1h),
4928 _par_scan_state(pss)
4929 { }
4931 void do_void() {
4932 G1ParScanThreadState* const pss = par_scan_state();
4933 pss->trim_queue();
4934 }
4935 };
4937 // Parallel Reference Processing closures
4939 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4940 // processing during G1 evacuation pauses.
4942 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4943 private:
4944 G1CollectedHeap* _g1h;
4945 RefToScanQueueSet* _queues;
4946 FlexibleWorkGang* _workers;
4947 int _active_workers;
4949 public:
4950 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4951 FlexibleWorkGang* workers,
4952 RefToScanQueueSet *task_queues,
4953 int n_workers) :
4954 _g1h(g1h),
4955 _queues(task_queues),
4956 _workers(workers),
4957 _active_workers(n_workers)
4958 {
4959 assert(n_workers > 0, "shouldn't call this otherwise");
4960 }
4962 // Executes the given task using concurrent marking worker threads.
4963 virtual void execute(ProcessTask& task);
4964 virtual void execute(EnqueueTask& task);
4965 };
4967 // Gang task for possibly parallel reference processing
4969 class G1STWRefProcTaskProxy: public AbstractGangTask {
4970 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4971 ProcessTask& _proc_task;
4972 G1CollectedHeap* _g1h;
4973 RefToScanQueueSet *_task_queues;
4974 ParallelTaskTerminator* _terminator;
4976 public:
4977 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4978 G1CollectedHeap* g1h,
4979 RefToScanQueueSet *task_queues,
4980 ParallelTaskTerminator* terminator) :
4981 AbstractGangTask("Process reference objects in parallel"),
4982 _proc_task(proc_task),
4983 _g1h(g1h),
4984 _task_queues(task_queues),
4985 _terminator(terminator)
4986 {}
4988 virtual void work(uint worker_id) {
4989 // The reference processing task executed by a single worker.
4990 ResourceMark rm;
4991 HandleMark hm;
4993 G1STWIsAliveClosure is_alive(_g1h);
4995 G1ParScanThreadState pss(_g1h, worker_id);
4997 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
4998 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
4999 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5001 pss.set_evac_closure(&scan_evac_cl);
5002 pss.set_evac_failure_closure(&evac_failure_cl);
5003 pss.set_partial_scan_closure(&partial_scan_cl);
5005 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5006 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5008 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5009 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5011 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5012 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5014 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5015 // We also need to mark copied objects.
5016 copy_non_heap_cl = ©_mark_non_heap_cl;
5017 copy_perm_cl = ©_mark_perm_cl;
5018 }
5020 // Keep alive closure.
5021 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5023 // Complete GC closure
5024 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5026 // Call the reference processing task's work routine.
5027 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5029 // Note we cannot assert that the refs array is empty here as not all
5030 // of the processing tasks (specifically phase2 - pp2_work) execute
5031 // the complete_gc closure (which ordinarily would drain the queue) so
5032 // the queue may not be empty.
5033 }
5034 };
5036 // Driver routine for parallel reference processing.
5037 // Creates an instance of the ref processing gang
5038 // task and has the worker threads execute it.
5039 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5040 assert(_workers != NULL, "Need parallel worker threads.");
5042 ParallelTaskTerminator terminator(_active_workers, _queues);
5043 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5045 _g1h->set_par_threads(_active_workers);
5046 _workers->run_task(&proc_task_proxy);
5047 _g1h->set_par_threads(0);
5048 }
5050 // Gang task for parallel reference enqueueing.
5052 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5053 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5054 EnqueueTask& _enq_task;
5056 public:
5057 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5058 AbstractGangTask("Enqueue reference objects in parallel"),
5059 _enq_task(enq_task)
5060 { }
5062 virtual void work(uint worker_id) {
5063 _enq_task.work(worker_id);
5064 }
5065 };
5067 // Driver routine for parallel reference enqueing.
5068 // Creates an instance of the ref enqueueing gang
5069 // task and has the worker threads execute it.
5071 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5072 assert(_workers != NULL, "Need parallel worker threads.");
5074 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5076 _g1h->set_par_threads(_active_workers);
5077 _workers->run_task(&enq_task_proxy);
5078 _g1h->set_par_threads(0);
5079 }
5081 // End of weak reference support closures
5083 // Abstract task used to preserve (i.e. copy) any referent objects
5084 // that are in the collection set and are pointed to by reference
5085 // objects discovered by the CM ref processor.
5087 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5088 protected:
5089 G1CollectedHeap* _g1h;
5090 RefToScanQueueSet *_queues;
5091 ParallelTaskTerminator _terminator;
5092 uint _n_workers;
5094 public:
5095 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5096 AbstractGangTask("ParPreserveCMReferents"),
5097 _g1h(g1h),
5098 _queues(task_queues),
5099 _terminator(workers, _queues),
5100 _n_workers(workers)
5101 { }
5103 void work(uint worker_id) {
5104 ResourceMark rm;
5105 HandleMark hm;
5107 G1ParScanThreadState pss(_g1h, worker_id);
5108 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5109 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5110 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5112 pss.set_evac_closure(&scan_evac_cl);
5113 pss.set_evac_failure_closure(&evac_failure_cl);
5114 pss.set_partial_scan_closure(&partial_scan_cl);
5116 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5119 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5120 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5122 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5123 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5125 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5126 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5128 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5129 // We also need to mark copied objects.
5130 copy_non_heap_cl = ©_mark_non_heap_cl;
5131 copy_perm_cl = ©_mark_perm_cl;
5132 }
5134 // Is alive closure
5135 G1AlwaysAliveClosure always_alive(_g1h);
5137 // Copying keep alive closure. Applied to referent objects that need
5138 // to be copied.
5139 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5141 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5143 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5144 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5146 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5147 // So this must be true - but assert just in case someone decides to
5148 // change the worker ids.
5149 assert(0 <= worker_id && worker_id < limit, "sanity");
5150 assert(!rp->discovery_is_atomic(), "check this code");
5152 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5153 for (uint idx = worker_id; idx < limit; idx += stride) {
5154 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5156 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5157 while (iter.has_next()) {
5158 // Since discovery is not atomic for the CM ref processor, we
5159 // can see some null referent objects.
5160 iter.load_ptrs(DEBUG_ONLY(true));
5161 oop ref = iter.obj();
5163 // This will filter nulls.
5164 if (iter.is_referent_alive()) {
5165 iter.make_referent_alive();
5166 }
5167 iter.move_to_next();
5168 }
5169 }
5171 // Drain the queue - which may cause stealing
5172 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5173 drain_queue.do_void();
5174 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5175 assert(pss.refs()->is_empty(), "should be");
5176 }
5177 };
5179 // Weak Reference processing during an evacuation pause (part 1).
5180 void G1CollectedHeap::process_discovered_references() {
5181 double ref_proc_start = os::elapsedTime();
5183 ReferenceProcessor* rp = _ref_processor_stw;
5184 assert(rp->discovery_enabled(), "should have been enabled");
5186 // Any reference objects, in the collection set, that were 'discovered'
5187 // by the CM ref processor should have already been copied (either by
5188 // applying the external root copy closure to the discovered lists, or
5189 // by following an RSet entry).
5190 //
5191 // But some of the referents, that are in the collection set, that these
5192 // reference objects point to may not have been copied: the STW ref
5193 // processor would have seen that the reference object had already
5194 // been 'discovered' and would have skipped discovering the reference,
5195 // but would not have treated the reference object as a regular oop.
5196 // As a reult the copy closure would not have been applied to the
5197 // referent object.
5198 //
5199 // We need to explicitly copy these referent objects - the references
5200 // will be processed at the end of remarking.
5201 //
5202 // We also need to do this copying before we process the reference
5203 // objects discovered by the STW ref processor in case one of these
5204 // referents points to another object which is also referenced by an
5205 // object discovered by the STW ref processor.
5207 uint active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5208 workers()->active_workers() : 1);
5210 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5211 active_workers == workers()->active_workers(),
5212 "Need to reset active_workers");
5214 set_par_threads(active_workers);
5215 G1ParPreserveCMReferentsTask keep_cm_referents(this, active_workers, _task_queues);
5217 if (G1CollectedHeap::use_parallel_gc_threads()) {
5218 workers()->run_task(&keep_cm_referents);
5219 } else {
5220 keep_cm_referents.work(0);
5221 }
5223 set_par_threads(0);
5225 // Closure to test whether a referent is alive.
5226 G1STWIsAliveClosure is_alive(this);
5228 // Even when parallel reference processing is enabled, the processing
5229 // of JNI refs is serial and performed serially by the current thread
5230 // rather than by a worker. The following PSS will be used for processing
5231 // JNI refs.
5233 // Use only a single queue for this PSS.
5234 G1ParScanThreadState pss(this, 0);
5236 // We do not embed a reference processor in the copying/scanning
5237 // closures while we're actually processing the discovered
5238 // reference objects.
5239 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5240 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5241 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5243 pss.set_evac_closure(&scan_evac_cl);
5244 pss.set_evac_failure_closure(&evac_failure_cl);
5245 pss.set_partial_scan_closure(&partial_scan_cl);
5247 assert(pss.refs()->is_empty(), "pre-condition");
5249 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5250 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL);
5252 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5253 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL);
5255 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5256 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5258 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5259 // We also need to mark copied objects.
5260 copy_non_heap_cl = ©_mark_non_heap_cl;
5261 copy_perm_cl = ©_mark_perm_cl;
5262 }
5264 // Keep alive closure.
5265 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5267 // Serial Complete GC closure
5268 G1STWDrainQueueClosure drain_queue(this, &pss);
5270 // Setup the soft refs policy...
5271 rp->setup_policy(false);
5273 if (!rp->processing_is_mt()) {
5274 // Serial reference processing...
5275 rp->process_discovered_references(&is_alive,
5276 &keep_alive,
5277 &drain_queue,
5278 NULL);
5279 } else {
5280 // Parallel reference processing
5281 assert(rp->num_q() == active_workers, "sanity");
5282 assert(active_workers <= rp->max_num_q(), "sanity");
5284 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5285 rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5286 }
5288 // We have completed copying any necessary live referent objects
5289 // (that were not copied during the actual pause) so we can
5290 // retire any active alloc buffers
5291 pss.retire_alloc_buffers();
5292 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5294 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5295 g1_policy()->record_ref_proc_time(ref_proc_time * 1000.0);
5296 }
5298 // Weak Reference processing during an evacuation pause (part 2).
5299 void G1CollectedHeap::enqueue_discovered_references() {
5300 double ref_enq_start = os::elapsedTime();
5302 ReferenceProcessor* rp = _ref_processor_stw;
5303 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5305 // Now enqueue any remaining on the discovered lists on to
5306 // the pending list.
5307 if (!rp->processing_is_mt()) {
5308 // Serial reference processing...
5309 rp->enqueue_discovered_references();
5310 } else {
5311 // Parallel reference enqueuing
5313 uint active_workers = (ParallelGCThreads > 0 ? workers()->active_workers() : 1);
5314 assert(active_workers == workers()->active_workers(),
5315 "Need to reset active_workers");
5316 assert(rp->num_q() == active_workers, "sanity");
5317 assert(active_workers <= rp->max_num_q(), "sanity");
5319 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5320 rp->enqueue_discovered_references(&par_task_executor);
5321 }
5323 rp->verify_no_references_recorded();
5324 assert(!rp->discovery_enabled(), "should have been disabled");
5326 // FIXME
5327 // CM's reference processing also cleans up the string and symbol tables.
5328 // Should we do that here also? We could, but it is a serial operation
5329 // and could signicantly increase the pause time.
5331 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5332 g1_policy()->record_ref_enq_time(ref_enq_time * 1000.0);
5333 }
5335 void G1CollectedHeap::evacuate_collection_set() {
5336 _expand_heap_after_alloc_failure = true;
5337 set_evacuation_failed(false);
5339 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5340 concurrent_g1_refine()->set_use_cache(false);
5341 concurrent_g1_refine()->clear_hot_cache_claimed_index();
5343 uint n_workers;
5344 if (G1CollectedHeap::use_parallel_gc_threads()) {
5345 n_workers =
5346 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5347 workers()->active_workers(),
5348 Threads::number_of_non_daemon_threads());
5349 assert(UseDynamicNumberOfGCThreads ||
5350 n_workers == workers()->total_workers(),
5351 "If not dynamic should be using all the workers");
5352 workers()->set_active_workers(n_workers);
5353 set_par_threads(n_workers);
5354 } else {
5355 assert(n_par_threads() == 0,
5356 "Should be the original non-parallel value");
5357 n_workers = 1;
5358 }
5360 G1ParTask g1_par_task(this, _task_queues);
5362 init_for_evac_failure(NULL);
5364 rem_set()->prepare_for_younger_refs_iterate(true);
5366 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5367 double start_par = os::elapsedTime();
5369 if (G1CollectedHeap::use_parallel_gc_threads()) {
5370 // The individual threads will set their evac-failure closures.
5371 StrongRootsScope srs(this);
5372 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5373 // These tasks use ShareHeap::_process_strong_tasks
5374 assert(UseDynamicNumberOfGCThreads ||
5375 workers()->active_workers() == workers()->total_workers(),
5376 "If not dynamic should be using all the workers");
5377 workers()->run_task(&g1_par_task);
5378 } else {
5379 StrongRootsScope srs(this);
5380 g1_par_task.set_for_termination(n_workers);
5381 g1_par_task.work(0);
5382 }
5384 double par_time = (os::elapsedTime() - start_par) * 1000.0;
5385 g1_policy()->record_par_time(par_time);
5387 set_par_threads(0);
5389 // Process any discovered reference objects - we have
5390 // to do this _before_ we retire the GC alloc regions
5391 // as we may have to copy some 'reachable' referent
5392 // objects (and their reachable sub-graphs) that were
5393 // not copied during the pause.
5394 process_discovered_references();
5396 // Weak root processing.
5397 // Note: when JSR 292 is enabled and code blobs can contain
5398 // non-perm oops then we will need to process the code blobs
5399 // here too.
5400 {
5401 G1STWIsAliveClosure is_alive(this);
5402 G1KeepAliveClosure keep_alive(this);
5403 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5404 }
5406 release_gc_alloc_regions();
5407 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5409 concurrent_g1_refine()->clear_hot_cache();
5410 concurrent_g1_refine()->set_use_cache(true);
5412 finalize_for_evac_failure();
5414 // Must do this before clearing the per-region evac-failure flags
5415 // (which is currently done when we free the collection set).
5416 // We also only do this if marking is actually in progress and so
5417 // have to do this before we set the mark_in_progress flag at the
5418 // end of an initial mark pause.
5419 concurrent_mark()->complete_marking_in_collection_set();
5421 if (evacuation_failed()) {
5422 remove_self_forwarding_pointers();
5423 if (PrintGCDetails) {
5424 gclog_or_tty->print(" (to-space overflow)");
5425 } else if (PrintGC) {
5426 gclog_or_tty->print("--");
5427 }
5428 }
5430 // Enqueue any remaining references remaining on the STW
5431 // reference processor's discovered lists. We need to do
5432 // this after the card table is cleaned (and verified) as
5433 // the act of enqueuing entries on to the pending list
5434 // will log these updates (and dirty their associated
5435 // cards). We need these updates logged to update any
5436 // RSets.
5437 enqueue_discovered_references();
5439 if (G1DeferredRSUpdate) {
5440 RedirtyLoggedCardTableEntryFastClosure redirty;
5441 dirty_card_queue_set().set_closure(&redirty);
5442 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5444 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5445 dcq.merge_bufferlists(&dirty_card_queue_set());
5446 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5447 }
5448 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5449 }
5451 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5452 size_t* pre_used,
5453 FreeRegionList* free_list,
5454 OldRegionSet* old_proxy_set,
5455 HumongousRegionSet* humongous_proxy_set,
5456 HRRSCleanupTask* hrrs_cleanup_task,
5457 bool par) {
5458 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5459 if (hr->isHumongous()) {
5460 assert(hr->startsHumongous(), "we should only see starts humongous");
5461 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5462 } else {
5463 _old_set.remove_with_proxy(hr, old_proxy_set);
5464 free_region(hr, pre_used, free_list, par);
5465 }
5466 } else {
5467 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5468 }
5469 }
5471 void G1CollectedHeap::free_region(HeapRegion* hr,
5472 size_t* pre_used,
5473 FreeRegionList* free_list,
5474 bool par) {
5475 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5476 assert(!hr->is_empty(), "the region should not be empty");
5477 assert(free_list != NULL, "pre-condition");
5479 *pre_used += hr->used();
5480 hr->hr_clear(par, true /* clear_space */);
5481 free_list->add_as_head(hr);
5482 }
5484 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5485 size_t* pre_used,
5486 FreeRegionList* free_list,
5487 HumongousRegionSet* humongous_proxy_set,
5488 bool par) {
5489 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5490 assert(free_list != NULL, "pre-condition");
5491 assert(humongous_proxy_set != NULL, "pre-condition");
5493 size_t hr_used = hr->used();
5494 size_t hr_capacity = hr->capacity();
5495 size_t hr_pre_used = 0;
5496 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5497 hr->set_notHumongous();
5498 free_region(hr, &hr_pre_used, free_list, par);
5500 size_t i = hr->hrs_index() + 1;
5501 size_t num = 1;
5502 while (i < n_regions()) {
5503 HeapRegion* curr_hr = region_at(i);
5504 if (!curr_hr->continuesHumongous()) {
5505 break;
5506 }
5507 curr_hr->set_notHumongous();
5508 free_region(curr_hr, &hr_pre_used, free_list, par);
5509 num += 1;
5510 i += 1;
5511 }
5512 assert(hr_pre_used == hr_used,
5513 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5514 "should be the same", hr_pre_used, hr_used));
5515 *pre_used += hr_pre_used;
5516 }
5518 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5519 FreeRegionList* free_list,
5520 OldRegionSet* old_proxy_set,
5521 HumongousRegionSet* humongous_proxy_set,
5522 bool par) {
5523 if (pre_used > 0) {
5524 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5525 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5526 assert(_summary_bytes_used >= pre_used,
5527 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5528 "should be >= pre_used: "SIZE_FORMAT,
5529 _summary_bytes_used, pre_used));
5530 _summary_bytes_used -= pre_used;
5531 }
5532 if (free_list != NULL && !free_list->is_empty()) {
5533 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5534 _free_list.add_as_head(free_list);
5535 }
5536 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5537 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5538 _old_set.update_from_proxy(old_proxy_set);
5539 }
5540 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5541 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5542 _humongous_set.update_from_proxy(humongous_proxy_set);
5543 }
5544 }
5546 class G1ParCleanupCTTask : public AbstractGangTask {
5547 CardTableModRefBS* _ct_bs;
5548 G1CollectedHeap* _g1h;
5549 HeapRegion* volatile _su_head;
5550 public:
5551 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5552 G1CollectedHeap* g1h) :
5553 AbstractGangTask("G1 Par Cleanup CT Task"),
5554 _ct_bs(ct_bs), _g1h(g1h) { }
5556 void work(uint worker_id) {
5557 HeapRegion* r;
5558 while (r = _g1h->pop_dirty_cards_region()) {
5559 clear_cards(r);
5560 }
5561 }
5563 void clear_cards(HeapRegion* r) {
5564 // Cards of the survivors should have already been dirtied.
5565 if (!r->is_survivor()) {
5566 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5567 }
5568 }
5569 };
5571 #ifndef PRODUCT
5572 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5573 G1CollectedHeap* _g1h;
5574 CardTableModRefBS* _ct_bs;
5575 public:
5576 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5577 : _g1h(g1h), _ct_bs(ct_bs) { }
5578 virtual bool doHeapRegion(HeapRegion* r) {
5579 if (r->is_survivor()) {
5580 _g1h->verify_dirty_region(r);
5581 } else {
5582 _g1h->verify_not_dirty_region(r);
5583 }
5584 return false;
5585 }
5586 };
5588 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5589 // All of the region should be clean.
5590 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5591 MemRegion mr(hr->bottom(), hr->end());
5592 ct_bs->verify_not_dirty_region(mr);
5593 }
5595 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5596 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5597 // dirty allocated blocks as they allocate them. The thread that
5598 // retires each region and replaces it with a new one will do a
5599 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5600 // not dirty that area (one less thing to have to do while holding
5601 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5602 // is dirty.
5603 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5604 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5605 ct_bs->verify_dirty_region(mr);
5606 }
5608 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5609 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5610 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5611 verify_dirty_region(hr);
5612 }
5613 }
5615 void G1CollectedHeap::verify_dirty_young_regions() {
5616 verify_dirty_young_list(_young_list->first_region());
5617 verify_dirty_young_list(_young_list->first_survivor_region());
5618 }
5619 #endif
5621 void G1CollectedHeap::cleanUpCardTable() {
5622 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5623 double start = os::elapsedTime();
5625 {
5626 // Iterate over the dirty cards region list.
5627 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5629 if (G1CollectedHeap::use_parallel_gc_threads()) {
5630 set_par_threads();
5631 workers()->run_task(&cleanup_task);
5632 set_par_threads(0);
5633 } else {
5634 while (_dirty_cards_region_list) {
5635 HeapRegion* r = _dirty_cards_region_list;
5636 cleanup_task.clear_cards(r);
5637 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5638 if (_dirty_cards_region_list == r) {
5639 // The last region.
5640 _dirty_cards_region_list = NULL;
5641 }
5642 r->set_next_dirty_cards_region(NULL);
5643 }
5644 }
5645 #ifndef PRODUCT
5646 if (G1VerifyCTCleanup || VerifyAfterGC) {
5647 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5648 heap_region_iterate(&cleanup_verifier);
5649 }
5650 #endif
5651 }
5653 double elapsed = os::elapsedTime() - start;
5654 g1_policy()->record_clear_ct_time(elapsed * 1000.0);
5655 }
5657 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5658 size_t pre_used = 0;
5659 FreeRegionList local_free_list("Local List for CSet Freeing");
5661 double young_time_ms = 0.0;
5662 double non_young_time_ms = 0.0;
5664 // Since the collection set is a superset of the the young list,
5665 // all we need to do to clear the young list is clear its
5666 // head and length, and unlink any young regions in the code below
5667 _young_list->clear();
5669 G1CollectorPolicy* policy = g1_policy();
5671 double start_sec = os::elapsedTime();
5672 bool non_young = true;
5674 HeapRegion* cur = cs_head;
5675 int age_bound = -1;
5676 size_t rs_lengths = 0;
5678 while (cur != NULL) {
5679 assert(!is_on_master_free_list(cur), "sanity");
5680 if (non_young) {
5681 if (cur->is_young()) {
5682 double end_sec = os::elapsedTime();
5683 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5684 non_young_time_ms += elapsed_ms;
5686 start_sec = os::elapsedTime();
5687 non_young = false;
5688 }
5689 } else {
5690 if (!cur->is_young()) {
5691 double end_sec = os::elapsedTime();
5692 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5693 young_time_ms += elapsed_ms;
5695 start_sec = os::elapsedTime();
5696 non_young = true;
5697 }
5698 }
5700 rs_lengths += cur->rem_set()->occupied();
5702 HeapRegion* next = cur->next_in_collection_set();
5703 assert(cur->in_collection_set(), "bad CS");
5704 cur->set_next_in_collection_set(NULL);
5705 cur->set_in_collection_set(false);
5707 if (cur->is_young()) {
5708 int index = cur->young_index_in_cset();
5709 assert(index != -1, "invariant");
5710 assert((size_t) index < policy->young_cset_region_length(), "invariant");
5711 size_t words_survived = _surviving_young_words[index];
5712 cur->record_surv_words_in_group(words_survived);
5714 // At this point the we have 'popped' cur from the collection set
5715 // (linked via next_in_collection_set()) but it is still in the
5716 // young list (linked via next_young_region()). Clear the
5717 // _next_young_region field.
5718 cur->set_next_young_region(NULL);
5719 } else {
5720 int index = cur->young_index_in_cset();
5721 assert(index == -1, "invariant");
5722 }
5724 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5725 (!cur->is_young() && cur->young_index_in_cset() == -1),
5726 "invariant" );
5728 if (!cur->evacuation_failed()) {
5729 MemRegion used_mr = cur->used_region();
5731 // And the region is empty.
5732 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5734 // If marking is in progress then clear any objects marked in
5735 // the current region. Note mark_in_progress() returns false,
5736 // even during an initial mark pause, until the set_marking_started()
5737 // call which takes place later in the pause.
5738 if (mark_in_progress()) {
5739 assert(!g1_policy()->during_initial_mark_pause(), "sanity");
5740 _cm->nextMarkBitMap()->clearRange(used_mr);
5741 }
5743 free_region(cur, &pre_used, &local_free_list, false /* par */);
5744 } else {
5745 cur->uninstall_surv_rate_group();
5746 if (cur->is_young()) {
5747 cur->set_young_index_in_cset(-1);
5748 }
5749 cur->set_not_young();
5750 cur->set_evacuation_failed(false);
5751 // The region is now considered to be old.
5752 _old_set.add(cur);
5753 }
5754 cur = next;
5755 }
5757 policy->record_max_rs_lengths(rs_lengths);
5758 policy->cset_regions_freed();
5760 double end_sec = os::elapsedTime();
5761 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5763 if (non_young) {
5764 non_young_time_ms += elapsed_ms;
5765 } else {
5766 young_time_ms += elapsed_ms;
5767 }
5769 update_sets_after_freeing_regions(pre_used, &local_free_list,
5770 NULL /* old_proxy_set */,
5771 NULL /* humongous_proxy_set */,
5772 false /* par */);
5773 policy->record_young_free_cset_time_ms(young_time_ms);
5774 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5775 }
5777 // This routine is similar to the above but does not record
5778 // any policy statistics or update free lists; we are abandoning
5779 // the current incremental collection set in preparation of a
5780 // full collection. After the full GC we will start to build up
5781 // the incremental collection set again.
5782 // This is only called when we're doing a full collection
5783 // and is immediately followed by the tearing down of the young list.
5785 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5786 HeapRegion* cur = cs_head;
5788 while (cur != NULL) {
5789 HeapRegion* next = cur->next_in_collection_set();
5790 assert(cur->in_collection_set(), "bad CS");
5791 cur->set_next_in_collection_set(NULL);
5792 cur->set_in_collection_set(false);
5793 cur->set_young_index_in_cset(-1);
5794 cur = next;
5795 }
5796 }
5798 void G1CollectedHeap::set_free_regions_coming() {
5799 if (G1ConcRegionFreeingVerbose) {
5800 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5801 "setting free regions coming");
5802 }
5804 assert(!free_regions_coming(), "pre-condition");
5805 _free_regions_coming = true;
5806 }
5808 void G1CollectedHeap::reset_free_regions_coming() {
5809 {
5810 assert(free_regions_coming(), "pre-condition");
5811 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5812 _free_regions_coming = false;
5813 SecondaryFreeList_lock->notify_all();
5814 }
5816 if (G1ConcRegionFreeingVerbose) {
5817 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5818 "reset free regions coming");
5819 }
5820 }
5822 void G1CollectedHeap::wait_while_free_regions_coming() {
5823 // Most of the time we won't have to wait, so let's do a quick test
5824 // first before we take the lock.
5825 if (!free_regions_coming()) {
5826 return;
5827 }
5829 if (G1ConcRegionFreeingVerbose) {
5830 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5831 "waiting for free regions");
5832 }
5834 {
5835 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5836 while (free_regions_coming()) {
5837 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5838 }
5839 }
5841 if (G1ConcRegionFreeingVerbose) {
5842 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5843 "done waiting for free regions");
5844 }
5845 }
5847 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5848 assert(heap_lock_held_for_gc(),
5849 "the heap lock should already be held by or for this thread");
5850 _young_list->push_region(hr);
5851 }
5853 class NoYoungRegionsClosure: public HeapRegionClosure {
5854 private:
5855 bool _success;
5856 public:
5857 NoYoungRegionsClosure() : _success(true) { }
5858 bool doHeapRegion(HeapRegion* r) {
5859 if (r->is_young()) {
5860 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5861 r->bottom(), r->end());
5862 _success = false;
5863 }
5864 return false;
5865 }
5866 bool success() { return _success; }
5867 };
5869 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5870 bool ret = _young_list->check_list_empty(check_sample);
5872 if (check_heap) {
5873 NoYoungRegionsClosure closure;
5874 heap_region_iterate(&closure);
5875 ret = ret && closure.success();
5876 }
5878 return ret;
5879 }
5881 class TearDownRegionSetsClosure : public HeapRegionClosure {
5882 private:
5883 OldRegionSet *_old_set;
5885 public:
5886 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
5888 bool doHeapRegion(HeapRegion* r) {
5889 if (r->is_empty()) {
5890 // We ignore empty regions, we'll empty the free list afterwards
5891 } else if (r->is_young()) {
5892 // We ignore young regions, we'll empty the young list afterwards
5893 } else if (r->isHumongous()) {
5894 // We ignore humongous regions, we're not tearing down the
5895 // humongous region set
5896 } else {
5897 // The rest should be old
5898 _old_set->remove(r);
5899 }
5900 return false;
5901 }
5903 ~TearDownRegionSetsClosure() {
5904 assert(_old_set->is_empty(), "post-condition");
5905 }
5906 };
5908 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5909 assert_at_safepoint(true /* should_be_vm_thread */);
5911 if (!free_list_only) {
5912 TearDownRegionSetsClosure cl(&_old_set);
5913 heap_region_iterate(&cl);
5915 // Need to do this after the heap iteration to be able to
5916 // recognize the young regions and ignore them during the iteration.
5917 _young_list->empty_list();
5918 }
5919 _free_list.remove_all();
5920 }
5922 class RebuildRegionSetsClosure : public HeapRegionClosure {
5923 private:
5924 bool _free_list_only;
5925 OldRegionSet* _old_set;
5926 FreeRegionList* _free_list;
5927 size_t _total_used;
5929 public:
5930 RebuildRegionSetsClosure(bool free_list_only,
5931 OldRegionSet* old_set, FreeRegionList* free_list) :
5932 _free_list_only(free_list_only),
5933 _old_set(old_set), _free_list(free_list), _total_used(0) {
5934 assert(_free_list->is_empty(), "pre-condition");
5935 if (!free_list_only) {
5936 assert(_old_set->is_empty(), "pre-condition");
5937 }
5938 }
5940 bool doHeapRegion(HeapRegion* r) {
5941 if (r->continuesHumongous()) {
5942 return false;
5943 }
5945 if (r->is_empty()) {
5946 // Add free regions to the free list
5947 _free_list->add_as_tail(r);
5948 } else if (!_free_list_only) {
5949 assert(!r->is_young(), "we should not come across young regions");
5951 if (r->isHumongous()) {
5952 // We ignore humongous regions, we left the humongous set unchanged
5953 } else {
5954 // The rest should be old, add them to the old set
5955 _old_set->add(r);
5956 }
5957 _total_used += r->used();
5958 }
5960 return false;
5961 }
5963 size_t total_used() {
5964 return _total_used;
5965 }
5966 };
5968 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5969 assert_at_safepoint(true /* should_be_vm_thread */);
5971 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
5972 heap_region_iterate(&cl);
5974 if (!free_list_only) {
5975 _summary_bytes_used = cl.total_used();
5976 }
5977 assert(_summary_bytes_used == recalculate_used(),
5978 err_msg("inconsistent _summary_bytes_used, "
5979 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
5980 _summary_bytes_used, recalculate_used()));
5981 }
5983 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5984 _refine_cte_cl->set_concurrent(concurrent);
5985 }
5987 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5988 HeapRegion* hr = heap_region_containing(p);
5989 if (hr == NULL) {
5990 return is_in_permanent(p);
5991 } else {
5992 return hr->is_in(p);
5993 }
5994 }
5996 // Methods for the mutator alloc region
5998 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5999 bool force) {
6000 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6001 assert(!force || g1_policy()->can_expand_young_list(),
6002 "if force is true we should be able to expand the young list");
6003 bool young_list_full = g1_policy()->is_young_list_full();
6004 if (force || !young_list_full) {
6005 HeapRegion* new_alloc_region = new_region(word_size,
6006 false /* do_expand */);
6007 if (new_alloc_region != NULL) {
6008 set_region_short_lived_locked(new_alloc_region);
6009 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6010 return new_alloc_region;
6011 }
6012 }
6013 return NULL;
6014 }
6016 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6017 size_t allocated_bytes) {
6018 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6019 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6021 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6022 _summary_bytes_used += allocated_bytes;
6023 _hr_printer.retire(alloc_region);
6024 // We update the eden sizes here, when the region is retired,
6025 // instead of when it's allocated, since this is the point that its
6026 // used space has been recored in _summary_bytes_used.
6027 g1mm()->update_eden_size();
6028 }
6030 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6031 bool force) {
6032 return _g1h->new_mutator_alloc_region(word_size, force);
6033 }
6035 void G1CollectedHeap::set_par_threads() {
6036 // Don't change the number of workers. Use the value previously set
6037 // in the workgroup.
6038 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6039 uint n_workers = workers()->active_workers();
6040 assert(UseDynamicNumberOfGCThreads ||
6041 n_workers == workers()->total_workers(),
6042 "Otherwise should be using the total number of workers");
6043 if (n_workers == 0) {
6044 assert(false, "Should have been set in prior evacuation pause.");
6045 n_workers = ParallelGCThreads;
6046 workers()->set_active_workers(n_workers);
6047 }
6048 set_par_threads(n_workers);
6049 }
6051 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6052 size_t allocated_bytes) {
6053 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6054 }
6056 // Methods for the GC alloc regions
6058 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6059 size_t count,
6060 GCAllocPurpose ap) {
6061 assert(FreeList_lock->owned_by_self(), "pre-condition");
6063 if (count < g1_policy()->max_regions(ap)) {
6064 HeapRegion* new_alloc_region = new_region(word_size,
6065 true /* do_expand */);
6066 if (new_alloc_region != NULL) {
6067 // We really only need to do this for old regions given that we
6068 // should never scan survivors. But it doesn't hurt to do it
6069 // for survivors too.
6070 new_alloc_region->set_saved_mark();
6071 if (ap == GCAllocForSurvived) {
6072 new_alloc_region->set_survivor();
6073 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6074 } else {
6075 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6076 }
6077 return new_alloc_region;
6078 } else {
6079 g1_policy()->note_alloc_region_limit_reached(ap);
6080 }
6081 }
6082 return NULL;
6083 }
6085 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6086 size_t allocated_bytes,
6087 GCAllocPurpose ap) {
6088 alloc_region->note_end_of_copying();
6089 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6090 if (ap == GCAllocForSurvived) {
6091 young_list()->add_survivor_region(alloc_region);
6092 } else {
6093 _old_set.add(alloc_region);
6094 }
6095 _hr_printer.retire(alloc_region);
6096 }
6098 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6099 bool force) {
6100 assert(!force, "not supported for GC alloc regions");
6101 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6102 }
6104 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6105 size_t allocated_bytes) {
6106 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6107 GCAllocForSurvived);
6108 }
6110 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6111 bool force) {
6112 assert(!force, "not supported for GC alloc regions");
6113 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6114 }
6116 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6117 size_t allocated_bytes) {
6118 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6119 GCAllocForTenured);
6120 }
6121 // Heap region set verification
6123 class VerifyRegionListsClosure : public HeapRegionClosure {
6124 private:
6125 FreeRegionList* _free_list;
6126 OldRegionSet* _old_set;
6127 HumongousRegionSet* _humongous_set;
6128 size_t _region_count;
6130 public:
6131 VerifyRegionListsClosure(OldRegionSet* old_set,
6132 HumongousRegionSet* humongous_set,
6133 FreeRegionList* free_list) :
6134 _old_set(old_set), _humongous_set(humongous_set),
6135 _free_list(free_list), _region_count(0) { }
6137 size_t region_count() { return _region_count; }
6139 bool doHeapRegion(HeapRegion* hr) {
6140 _region_count += 1;
6142 if (hr->continuesHumongous()) {
6143 return false;
6144 }
6146 if (hr->is_young()) {
6147 // TODO
6148 } else if (hr->startsHumongous()) {
6149 _humongous_set->verify_next_region(hr);
6150 } else if (hr->is_empty()) {
6151 _free_list->verify_next_region(hr);
6152 } else {
6153 _old_set->verify_next_region(hr);
6154 }
6155 return false;
6156 }
6157 };
6159 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index,
6160 HeapWord* bottom) {
6161 HeapWord* end = bottom + HeapRegion::GrainWords;
6162 MemRegion mr(bottom, end);
6163 assert(_g1_reserved.contains(mr), "invariant");
6164 // This might return NULL if the allocation fails
6165 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6166 }
6168 void G1CollectedHeap::verify_region_sets() {
6169 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6171 // First, check the explicit lists.
6172 _free_list.verify();
6173 {
6174 // Given that a concurrent operation might be adding regions to
6175 // the secondary free list we have to take the lock before
6176 // verifying it.
6177 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6178 _secondary_free_list.verify();
6179 }
6180 _old_set.verify();
6181 _humongous_set.verify();
6183 // If a concurrent region freeing operation is in progress it will
6184 // be difficult to correctly attributed any free regions we come
6185 // across to the correct free list given that they might belong to
6186 // one of several (free_list, secondary_free_list, any local lists,
6187 // etc.). So, if that's the case we will skip the rest of the
6188 // verification operation. Alternatively, waiting for the concurrent
6189 // operation to complete will have a non-trivial effect on the GC's
6190 // operation (no concurrent operation will last longer than the
6191 // interval between two calls to verification) and it might hide
6192 // any issues that we would like to catch during testing.
6193 if (free_regions_coming()) {
6194 return;
6195 }
6197 // Make sure we append the secondary_free_list on the free_list so
6198 // that all free regions we will come across can be safely
6199 // attributed to the free_list.
6200 append_secondary_free_list_if_not_empty_with_lock();
6202 // Finally, make sure that the region accounting in the lists is
6203 // consistent with what we see in the heap.
6204 _old_set.verify_start();
6205 _humongous_set.verify_start();
6206 _free_list.verify_start();
6208 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6209 heap_region_iterate(&cl);
6211 _old_set.verify_end();
6212 _humongous_set.verify_end();
6213 _free_list.verify_end();
6214 }