Mon, 10 Jan 2011 17:14:53 -0500
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
Summary: Make JvmtiGCMark safe to run non-safepoint and instrument CMS
Reviewed-by: ysr, dcubed
1 /*
2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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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/concurrentZFThread.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1MarkSweep.hpp"
35 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
36 #include "gc_implementation/g1/g1RemSet.inline.hpp"
37 #include "gc_implementation/g1/heapRegionRemSet.hpp"
38 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
39 #include "gc_implementation/g1/vm_operations_g1.hpp"
40 #include "gc_implementation/shared/isGCActiveMark.hpp"
41 #include "memory/gcLocker.inline.hpp"
42 #include "memory/genOopClosures.inline.hpp"
43 #include "memory/generationSpec.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/oop.pcgc.inline.hpp"
46 #include "runtime/aprofiler.hpp"
47 #include "runtime/vmThread.hpp"
49 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
51 // turn it on so that the contents of the young list (scan-only /
52 // to-be-collected) are printed at "strategic" points before / during
53 // / after the collection --- this is useful for debugging
54 #define YOUNG_LIST_VERBOSE 0
55 // CURRENT STATUS
56 // This file is under construction. Search for "FIXME".
58 // INVARIANTS/NOTES
59 //
60 // All allocation activity covered by the G1CollectedHeap interface is
61 // serialized by acquiring the HeapLock. This happens in mem_allocate
62 // and allocate_new_tlab, which are the "entry" points to the
63 // allocation code from the rest of the JVM. (Note that this does not
64 // apply to TLAB allocation, which is not part of this interface: it
65 // is done by clients of this interface.)
67 // Local to this file.
69 class RefineCardTableEntryClosure: public CardTableEntryClosure {
70 SuspendibleThreadSet* _sts;
71 G1RemSet* _g1rs;
72 ConcurrentG1Refine* _cg1r;
73 bool _concurrent;
74 public:
75 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
76 G1RemSet* g1rs,
77 ConcurrentG1Refine* cg1r) :
78 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
79 {}
80 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
81 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
82 // This path is executed by the concurrent refine or mutator threads,
83 // concurrently, and so we do not care if card_ptr contains references
84 // that point into the collection set.
85 assert(!oops_into_cset, "should be");
87 if (_concurrent && _sts->should_yield()) {
88 // Caller will actually yield.
89 return false;
90 }
91 // Otherwise, we finished successfully; return true.
92 return true;
93 }
94 void set_concurrent(bool b) { _concurrent = b; }
95 };
98 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
99 int _calls;
100 G1CollectedHeap* _g1h;
101 CardTableModRefBS* _ctbs;
102 int _histo[256];
103 public:
104 ClearLoggedCardTableEntryClosure() :
105 _calls(0)
106 {
107 _g1h = G1CollectedHeap::heap();
108 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
109 for (int i = 0; i < 256; i++) _histo[i] = 0;
110 }
111 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
112 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
113 _calls++;
114 unsigned char* ujb = (unsigned char*)card_ptr;
115 int ind = (int)(*ujb);
116 _histo[ind]++;
117 *card_ptr = -1;
118 }
119 return true;
120 }
121 int calls() { return _calls; }
122 void print_histo() {
123 gclog_or_tty->print_cr("Card table value histogram:");
124 for (int i = 0; i < 256; i++) {
125 if (_histo[i] != 0) {
126 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
127 }
128 }
129 }
130 };
132 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
133 int _calls;
134 G1CollectedHeap* _g1h;
135 CardTableModRefBS* _ctbs;
136 public:
137 RedirtyLoggedCardTableEntryClosure() :
138 _calls(0)
139 {
140 _g1h = G1CollectedHeap::heap();
141 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
142 }
143 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
144 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
145 _calls++;
146 *card_ptr = 0;
147 }
148 return true;
149 }
150 int calls() { return _calls; }
151 };
153 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
154 public:
155 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
156 *card_ptr = CardTableModRefBS::dirty_card_val();
157 return true;
158 }
159 };
161 YoungList::YoungList(G1CollectedHeap* g1h)
162 : _g1h(g1h), _head(NULL),
163 _length(0),
164 _last_sampled_rs_lengths(0),
165 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
166 {
167 guarantee( check_list_empty(false), "just making sure..." );
168 }
170 void YoungList::push_region(HeapRegion *hr) {
171 assert(!hr->is_young(), "should not already be young");
172 assert(hr->get_next_young_region() == NULL, "cause it should!");
174 hr->set_next_young_region(_head);
175 _head = hr;
177 hr->set_young();
178 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
179 ++_length;
180 }
182 void YoungList::add_survivor_region(HeapRegion* hr) {
183 assert(hr->is_survivor(), "should be flagged as survivor region");
184 assert(hr->get_next_young_region() == NULL, "cause it should!");
186 hr->set_next_young_region(_survivor_head);
187 if (_survivor_head == NULL) {
188 _survivor_tail = hr;
189 }
190 _survivor_head = hr;
192 ++_survivor_length;
193 }
195 void YoungList::empty_list(HeapRegion* list) {
196 while (list != NULL) {
197 HeapRegion* next = list->get_next_young_region();
198 list->set_next_young_region(NULL);
199 list->uninstall_surv_rate_group();
200 list->set_not_young();
201 list = next;
202 }
203 }
205 void YoungList::empty_list() {
206 assert(check_list_well_formed(), "young list should be well formed");
208 empty_list(_head);
209 _head = NULL;
210 _length = 0;
212 empty_list(_survivor_head);
213 _survivor_head = NULL;
214 _survivor_tail = NULL;
215 _survivor_length = 0;
217 _last_sampled_rs_lengths = 0;
219 assert(check_list_empty(false), "just making sure...");
220 }
222 bool YoungList::check_list_well_formed() {
223 bool ret = true;
225 size_t length = 0;
226 HeapRegion* curr = _head;
227 HeapRegion* last = NULL;
228 while (curr != NULL) {
229 if (!curr->is_young()) {
230 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
231 "incorrectly tagged (y: %d, surv: %d)",
232 curr->bottom(), curr->end(),
233 curr->is_young(), curr->is_survivor());
234 ret = false;
235 }
236 ++length;
237 last = curr;
238 curr = curr->get_next_young_region();
239 }
240 ret = ret && (length == _length);
242 if (!ret) {
243 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
244 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
245 length, _length);
246 }
248 return ret;
249 }
251 bool YoungList::check_list_empty(bool check_sample) {
252 bool ret = true;
254 if (_length != 0) {
255 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
256 _length);
257 ret = false;
258 }
259 if (check_sample && _last_sampled_rs_lengths != 0) {
260 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
261 ret = false;
262 }
263 if (_head != NULL) {
264 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
265 ret = false;
266 }
267 if (!ret) {
268 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
269 }
271 return ret;
272 }
274 void
275 YoungList::rs_length_sampling_init() {
276 _sampled_rs_lengths = 0;
277 _curr = _head;
278 }
280 bool
281 YoungList::rs_length_sampling_more() {
282 return _curr != NULL;
283 }
285 void
286 YoungList::rs_length_sampling_next() {
287 assert( _curr != NULL, "invariant" );
288 size_t rs_length = _curr->rem_set()->occupied();
290 _sampled_rs_lengths += rs_length;
292 // The current region may not yet have been added to the
293 // incremental collection set (it gets added when it is
294 // retired as the current allocation region).
295 if (_curr->in_collection_set()) {
296 // Update the collection set policy information for this region
297 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
298 }
300 _curr = _curr->get_next_young_region();
301 if (_curr == NULL) {
302 _last_sampled_rs_lengths = _sampled_rs_lengths;
303 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
304 }
305 }
307 void
308 YoungList::reset_auxilary_lists() {
309 guarantee( is_empty(), "young list should be empty" );
310 assert(check_list_well_formed(), "young list should be well formed");
312 // Add survivor regions to SurvRateGroup.
313 _g1h->g1_policy()->note_start_adding_survivor_regions();
314 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
316 for (HeapRegion* curr = _survivor_head;
317 curr != NULL;
318 curr = curr->get_next_young_region()) {
319 _g1h->g1_policy()->set_region_survivors(curr);
321 // The region is a non-empty survivor so let's add it to
322 // the incremental collection set for the next evacuation
323 // pause.
324 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
325 }
326 _g1h->g1_policy()->note_stop_adding_survivor_regions();
328 _head = _survivor_head;
329 _length = _survivor_length;
330 if (_survivor_head != NULL) {
331 assert(_survivor_tail != NULL, "cause it shouldn't be");
332 assert(_survivor_length > 0, "invariant");
333 _survivor_tail->set_next_young_region(NULL);
334 }
336 // Don't clear the survivor list handles until the start of
337 // the next evacuation pause - we need it in order to re-tag
338 // the survivor regions from this evacuation pause as 'young'
339 // at the start of the next.
341 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
343 assert(check_list_well_formed(), "young list should be well formed");
344 }
346 void YoungList::print() {
347 HeapRegion* lists[] = {_head, _survivor_head};
348 const char* names[] = {"YOUNG", "SURVIVOR"};
350 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
351 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
352 HeapRegion *curr = lists[list];
353 if (curr == NULL)
354 gclog_or_tty->print_cr(" empty");
355 while (curr != NULL) {
356 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
357 "age: %4d, y: %d, surv: %d",
358 curr->bottom(), curr->end(),
359 curr->top(),
360 curr->prev_top_at_mark_start(),
361 curr->next_top_at_mark_start(),
362 curr->top_at_conc_mark_count(),
363 curr->age_in_surv_rate_group_cond(),
364 curr->is_young(),
365 curr->is_survivor());
366 curr = curr->get_next_young_region();
367 }
368 }
370 gclog_or_tty->print_cr("");
371 }
373 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
374 {
375 // Claim the right to put the region on the dirty cards region list
376 // by installing a self pointer.
377 HeapRegion* next = hr->get_next_dirty_cards_region();
378 if (next == NULL) {
379 HeapRegion* res = (HeapRegion*)
380 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
381 NULL);
382 if (res == NULL) {
383 HeapRegion* head;
384 do {
385 // Put the region to the dirty cards region list.
386 head = _dirty_cards_region_list;
387 next = (HeapRegion*)
388 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
389 if (next == head) {
390 assert(hr->get_next_dirty_cards_region() == hr,
391 "hr->get_next_dirty_cards_region() != hr");
392 if (next == NULL) {
393 // The last region in the list points to itself.
394 hr->set_next_dirty_cards_region(hr);
395 } else {
396 hr->set_next_dirty_cards_region(next);
397 }
398 }
399 } while (next != head);
400 }
401 }
402 }
404 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
405 {
406 HeapRegion* head;
407 HeapRegion* hr;
408 do {
409 head = _dirty_cards_region_list;
410 if (head == NULL) {
411 return NULL;
412 }
413 HeapRegion* new_head = head->get_next_dirty_cards_region();
414 if (head == new_head) {
415 // The last region.
416 new_head = NULL;
417 }
418 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
419 head);
420 } while (hr != head);
421 assert(hr != NULL, "invariant");
422 hr->set_next_dirty_cards_region(NULL);
423 return hr;
424 }
426 void G1CollectedHeap::stop_conc_gc_threads() {
427 _cg1r->stop();
428 _czft->stop();
429 _cmThread->stop();
430 }
433 void G1CollectedHeap::check_ct_logs_at_safepoint() {
434 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
435 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
437 // Count the dirty cards at the start.
438 CountNonCleanMemRegionClosure count1(this);
439 ct_bs->mod_card_iterate(&count1);
440 int orig_count = count1.n();
442 // First clear the logged cards.
443 ClearLoggedCardTableEntryClosure clear;
444 dcqs.set_closure(&clear);
445 dcqs.apply_closure_to_all_completed_buffers();
446 dcqs.iterate_closure_all_threads(false);
447 clear.print_histo();
449 // Now ensure that there's no dirty cards.
450 CountNonCleanMemRegionClosure count2(this);
451 ct_bs->mod_card_iterate(&count2);
452 if (count2.n() != 0) {
453 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
454 count2.n(), orig_count);
455 }
456 guarantee(count2.n() == 0, "Card table should be clean.");
458 RedirtyLoggedCardTableEntryClosure redirty;
459 JavaThread::dirty_card_queue_set().set_closure(&redirty);
460 dcqs.apply_closure_to_all_completed_buffers();
461 dcqs.iterate_closure_all_threads(false);
462 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
463 clear.calls(), orig_count);
464 guarantee(redirty.calls() == clear.calls(),
465 "Or else mechanism is broken.");
467 CountNonCleanMemRegionClosure count3(this);
468 ct_bs->mod_card_iterate(&count3);
469 if (count3.n() != orig_count) {
470 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
471 orig_count, count3.n());
472 guarantee(count3.n() >= orig_count, "Should have restored them all.");
473 }
475 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
476 }
478 // Private class members.
480 G1CollectedHeap* G1CollectedHeap::_g1h;
482 // Private methods.
484 // Finds a HeapRegion that can be used to allocate a given size of block.
487 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
488 bool do_expand,
489 bool zero_filled) {
490 ConcurrentZFThread::note_region_alloc();
491 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
492 if (res == NULL && do_expand) {
493 expand(word_size * HeapWordSize);
494 res = alloc_free_region_from_lists(zero_filled);
495 assert(res == NULL ||
496 (!res->isHumongous() &&
497 (!zero_filled ||
498 res->zero_fill_state() == HeapRegion::Allocated)),
499 "Alloc Regions must be zero filled (and non-H)");
500 }
501 if (res != NULL) {
502 if (res->is_empty()) {
503 _free_regions--;
504 }
505 assert(!res->isHumongous() &&
506 (!zero_filled || res->zero_fill_state() == HeapRegion::Allocated),
507 err_msg("Non-young alloc Regions must be zero filled (and non-H):"
508 " res->isHumongous()=%d, zero_filled=%d, res->zero_fill_state()=%d",
509 res->isHumongous(), zero_filled, res->zero_fill_state()));
510 assert(!res->is_on_unclean_list(),
511 "Alloc Regions must not be on the unclean list");
512 if (G1PrintHeapRegions) {
513 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
514 "top "PTR_FORMAT,
515 res->hrs_index(), res->bottom(), res->end(), res->top());
516 }
517 }
518 return res;
519 }
521 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
522 size_t word_size,
523 bool zero_filled) {
524 HeapRegion* alloc_region = NULL;
525 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
526 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
527 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
528 alloc_region->set_survivor();
529 }
530 ++_gc_alloc_region_counts[purpose];
531 } else {
532 g1_policy()->note_alloc_region_limit_reached(purpose);
533 }
534 return alloc_region;
535 }
537 // If could fit into free regions w/o expansion, try.
538 // Otherwise, if can expand, do so.
539 // Otherwise, if using ex regions might help, try with ex given back.
540 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
541 assert_heap_locked_or_at_safepoint();
542 assert(regions_accounted_for(), "Region leakage!");
544 // We can't allocate humongous regions while cleanupComplete is
545 // running, since some of the regions we find to be empty might not
546 // yet be added to the unclean list. If we're already at a
547 // safepoint, this call is unnecessary, not to mention wrong.
548 if (!SafepointSynchronize::is_at_safepoint()) {
549 wait_for_cleanup_complete();
550 }
552 size_t num_regions =
553 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
555 // Special case if < one region???
557 // Remember the ft size.
558 size_t x_size = expansion_regions();
560 HeapWord* res = NULL;
561 bool eliminated_allocated_from_lists = false;
563 // Can the allocation potentially fit in the free regions?
564 if (free_regions() >= num_regions) {
565 res = _hrs->obj_allocate(word_size);
566 }
567 if (res == NULL) {
568 // Try expansion.
569 size_t fs = _hrs->free_suffix();
570 if (fs + x_size >= num_regions) {
571 expand((num_regions - fs) * HeapRegion::GrainBytes);
572 res = _hrs->obj_allocate(word_size);
573 assert(res != NULL, "This should have worked.");
574 } else {
575 // Expansion won't help. Are there enough free regions if we get rid
576 // of reservations?
577 size_t avail = free_regions();
578 if (avail >= num_regions) {
579 res = _hrs->obj_allocate(word_size);
580 if (res != NULL) {
581 remove_allocated_regions_from_lists();
582 eliminated_allocated_from_lists = true;
583 }
584 }
585 }
586 }
587 if (res != NULL) {
588 // Increment by the number of regions allocated.
589 // FIXME: Assumes regions all of size GrainBytes.
590 #ifndef PRODUCT
591 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
592 HeapRegion::GrainWords));
593 #endif
594 if (!eliminated_allocated_from_lists)
595 remove_allocated_regions_from_lists();
596 _summary_bytes_used += word_size * HeapWordSize;
597 _free_regions -= num_regions;
598 _num_humongous_regions += (int) num_regions;
599 }
600 assert(regions_accounted_for(), "Region Leakage");
601 return res;
602 }
604 void
605 G1CollectedHeap::retire_cur_alloc_region(HeapRegion* cur_alloc_region) {
606 // The cleanup operation might update _summary_bytes_used
607 // concurrently with this method. So, right now, if we don't wait
608 // for it to complete, updates to _summary_bytes_used might get
609 // lost. This will be resolved in the near future when the operation
610 // of the free region list is revamped as part of CR 6977804.
611 wait_for_cleanup_complete();
613 retire_cur_alloc_region_common(cur_alloc_region);
614 assert(_cur_alloc_region == NULL, "post-condition");
615 }
617 // See the comment in the .hpp file about the locking protocol and
618 // assumptions of this method (and other related ones).
619 HeapWord*
620 G1CollectedHeap::replace_cur_alloc_region_and_allocate(size_t word_size,
621 bool at_safepoint,
622 bool do_dirtying,
623 bool can_expand) {
624 assert_heap_locked_or_at_safepoint();
625 assert(_cur_alloc_region == NULL,
626 "replace_cur_alloc_region_and_allocate() should only be called "
627 "after retiring the previous current alloc region");
628 assert(SafepointSynchronize::is_at_safepoint() == at_safepoint,
629 "at_safepoint and is_at_safepoint() should be a tautology");
630 assert(!can_expand || g1_policy()->can_expand_young_list(),
631 "we should not call this method with can_expand == true if "
632 "we are not allowed to expand the young gen");
634 if (can_expand || !g1_policy()->is_young_list_full()) {
635 if (!at_safepoint) {
636 // The cleanup operation might update _summary_bytes_used
637 // concurrently with this method. So, right now, if we don't
638 // wait for it to complete, updates to _summary_bytes_used might
639 // get lost. This will be resolved in the near future when the
640 // operation of the free region list is revamped as part of
641 // CR 6977804. If we're already at a safepoint, this call is
642 // unnecessary, not to mention wrong.
643 wait_for_cleanup_complete();
644 }
646 HeapRegion* new_cur_alloc_region = newAllocRegion(word_size,
647 false /* zero_filled */);
648 if (new_cur_alloc_region != NULL) {
649 assert(new_cur_alloc_region->is_empty(),
650 "the newly-allocated region should be empty, "
651 "as right now we only allocate new regions out of the free list");
652 g1_policy()->update_region_num(true /* next_is_young */);
653 _summary_bytes_used -= new_cur_alloc_region->used();
654 set_region_short_lived_locked(new_cur_alloc_region);
656 assert(!new_cur_alloc_region->isHumongous(),
657 "Catch a regression of this bug.");
659 // We need to ensure that the stores to _cur_alloc_region and,
660 // subsequently, to top do not float above the setting of the
661 // young type.
662 OrderAccess::storestore();
664 // Now allocate out of the new current alloc region. We could
665 // have re-used allocate_from_cur_alloc_region() but its
666 // operation is slightly different to what we need here. First,
667 // allocate_from_cur_alloc_region() is only called outside a
668 // safepoint and will always unlock the Heap_lock if it returns
669 // a non-NULL result. Second, it assumes that the current alloc
670 // region is what's already assigned in _cur_alloc_region. What
671 // we want here is to actually do the allocation first before we
672 // assign the new region to _cur_alloc_region. This ordering is
673 // not currently important, but it will be essential when we
674 // change the code to support CAS allocation in the future (see
675 // CR 6994297).
676 //
677 // This allocate method does BOT updates and we don't need them in
678 // the young generation. This will be fixed in the near future by
679 // CR 6994297.
680 HeapWord* result = new_cur_alloc_region->allocate(word_size);
681 assert(result != NULL, "we just allocate out of an empty region "
682 "so allocation should have been successful");
683 assert(is_in(result), "result should be in the heap");
685 _cur_alloc_region = new_cur_alloc_region;
687 if (!at_safepoint) {
688 Heap_lock->unlock();
689 }
691 // do the dirtying, if necessary, after we release the Heap_lock
692 if (do_dirtying) {
693 dirty_young_block(result, word_size);
694 }
695 return result;
696 }
697 }
699 assert(_cur_alloc_region == NULL, "we failed to allocate a new current "
700 "alloc region, it should still be NULL");
701 assert_heap_locked_or_at_safepoint();
702 return NULL;
703 }
705 // See the comment in the .hpp file about the locking protocol and
706 // assumptions of this method (and other related ones).
707 HeapWord*
708 G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
709 assert_heap_locked_and_not_at_safepoint();
710 assert(!isHumongous(word_size), "attempt_allocation_slow() should not be "
711 "used for humongous allocations");
713 // We will loop while succeeded is false, which means that we tried
714 // to do a collection, but the VM op did not succeed. So, when we
715 // exit the loop, either one of the allocation attempts was
716 // successful, or we succeeded in doing the VM op but which was
717 // unable to allocate after the collection.
718 for (int try_count = 1; /* we'll return or break */; try_count += 1) {
719 bool succeeded = true;
721 {
722 // We may have concurrent cleanup working at the time. Wait for
723 // it to complete. In the future we would probably want to make
724 // the concurrent cleanup truly concurrent by decoupling it from
725 // the allocation. This will happen in the near future as part
726 // of CR 6977804 which will revamp the operation of the free
727 // region list. The fact that wait_for_cleanup_complete() will
728 // do a wait() means that we'll give up the Heap_lock. So, it's
729 // possible that when we exit wait_for_cleanup_complete() we
730 // might be able to allocate successfully (since somebody else
731 // might have done a collection meanwhile). So, we'll attempt to
732 // allocate again, just in case. When we make cleanup truly
733 // concurrent with allocation, we should remove this allocation
734 // attempt as it's redundant (we only reach here after an
735 // allocation attempt has been unsuccessful).
736 wait_for_cleanup_complete();
737 HeapWord* result = attempt_allocation(word_size);
738 if (result != NULL) {
739 assert_heap_not_locked();
740 return result;
741 }
742 }
744 if (GC_locker::is_active_and_needs_gc()) {
745 // We are locked out of GC because of the GC locker. We can
746 // allocate a new region only if we can expand the young gen.
748 if (g1_policy()->can_expand_young_list()) {
749 // Yes, we are allowed to expand the young gen. Let's try to
750 // allocate a new current alloc region.
752 HeapWord* result =
753 replace_cur_alloc_region_and_allocate(word_size,
754 false, /* at_safepoint */
755 true, /* do_dirtying */
756 true /* can_expand */);
757 if (result != NULL) {
758 assert_heap_not_locked();
759 return result;
760 }
761 }
762 // We could not expand the young gen further (or we could but we
763 // failed to allocate a new region). We'll stall until the GC
764 // locker forces a GC.
766 // If this thread is not in a jni critical section, we stall
767 // the requestor until the critical section has cleared and
768 // GC allowed. When the critical section clears, a GC is
769 // initiated by the last thread exiting the critical section; so
770 // we retry the allocation sequence from the beginning of the loop,
771 // rather than causing more, now probably unnecessary, GC attempts.
772 JavaThread* jthr = JavaThread::current();
773 assert(jthr != NULL, "sanity");
774 if (!jthr->in_critical()) {
775 MutexUnlocker mul(Heap_lock);
776 GC_locker::stall_until_clear();
778 // We'll then fall off the end of the ("if GC locker active")
779 // if-statement and retry the allocation further down in the
780 // loop.
781 } else {
782 if (CheckJNICalls) {
783 fatal("Possible deadlock due to allocating while"
784 " in jni critical section");
785 }
786 return NULL;
787 }
788 } else {
789 // We are not locked out. So, let's try to do a GC. The VM op
790 // will retry the allocation before it completes.
792 // Read the GC count while holding the Heap_lock
793 unsigned int gc_count_before = SharedHeap::heap()->total_collections();
795 Heap_lock->unlock();
797 HeapWord* result =
798 do_collection_pause(word_size, gc_count_before, &succeeded);
799 assert_heap_not_locked();
800 if (result != NULL) {
801 assert(succeeded, "the VM op should have succeeded");
803 // Allocations that take place on VM operations do not do any
804 // card dirtying and we have to do it here.
805 dirty_young_block(result, word_size);
806 return result;
807 }
809 Heap_lock->lock();
810 }
812 assert_heap_locked();
814 // We can reach here when we were unsuccessful in doing a GC,
815 // because another thread beat us to it, or because we were locked
816 // out of GC due to the GC locker. In either case a new alloc
817 // region might be available so we will retry the allocation.
818 HeapWord* result = attempt_allocation(word_size);
819 if (result != NULL) {
820 assert_heap_not_locked();
821 return result;
822 }
824 // So far our attempts to allocate failed. The only time we'll go
825 // around the loop and try again is if we tried to do a GC and the
826 // VM op that we tried to schedule was not successful because
827 // another thread beat us to it. If that happened it's possible
828 // that by the time we grabbed the Heap_lock again and tried to
829 // allocate other threads filled up the young generation, which
830 // means that the allocation attempt after the GC also failed. So,
831 // it's worth trying to schedule another GC pause.
832 if (succeeded) {
833 break;
834 }
836 // Give a warning if we seem to be looping forever.
837 if ((QueuedAllocationWarningCount > 0) &&
838 (try_count % QueuedAllocationWarningCount == 0)) {
839 warning("G1CollectedHeap::attempt_allocation_slow() "
840 "retries %d times", try_count);
841 }
842 }
844 assert_heap_locked();
845 return NULL;
846 }
848 // See the comment in the .hpp file about the locking protocol and
849 // assumptions of this method (and other related ones).
850 HeapWord*
851 G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
852 bool at_safepoint) {
853 // This is the method that will allocate a humongous object. All
854 // allocation paths that attempt to allocate a humongous object
855 // should eventually reach here. Currently, the only paths are from
856 // mem_allocate() and attempt_allocation_at_safepoint().
857 assert_heap_locked_or_at_safepoint();
858 assert(isHumongous(word_size), "attempt_allocation_humongous() "
859 "should only be used for humongous allocations");
860 assert(SafepointSynchronize::is_at_safepoint() == at_safepoint,
861 "at_safepoint and is_at_safepoint() should be a tautology");
863 HeapWord* result = NULL;
865 // We will loop while succeeded is false, which means that we tried
866 // to do a collection, but the VM op did not succeed. So, when we
867 // exit the loop, either one of the allocation attempts was
868 // successful, or we succeeded in doing the VM op but which was
869 // unable to allocate after the collection.
870 for (int try_count = 1; /* we'll return or break */; try_count += 1) {
871 bool succeeded = true;
873 // Given that humongous objects are not allocated in young
874 // regions, we'll first try to do the allocation without doing a
875 // collection hoping that there's enough space in the heap.
876 result = humongous_obj_allocate(word_size);
877 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
878 "catch a regression of this bug.");
879 if (result != NULL) {
880 if (!at_safepoint) {
881 // If we're not at a safepoint, unlock the Heap_lock.
882 Heap_lock->unlock();
883 }
884 return result;
885 }
887 // If we failed to allocate the humongous object, we should try to
888 // do a collection pause (if we're allowed) in case it reclaims
889 // enough space for the allocation to succeed after the pause.
890 if (!at_safepoint) {
891 // Read the GC count while holding the Heap_lock
892 unsigned int gc_count_before = SharedHeap::heap()->total_collections();
894 // If we're allowed to do a collection we're not at a
895 // safepoint, so it is safe to unlock the Heap_lock.
896 Heap_lock->unlock();
898 result = do_collection_pause(word_size, gc_count_before, &succeeded);
899 assert_heap_not_locked();
900 if (result != NULL) {
901 assert(succeeded, "the VM op should have succeeded");
902 return result;
903 }
905 // If we get here, the VM operation either did not succeed
906 // (i.e., another thread beat us to it) or it succeeded but
907 // failed to allocate the object.
909 // If we're allowed to do a collection we're not at a
910 // safepoint, so it is safe to lock the Heap_lock.
911 Heap_lock->lock();
912 }
914 assert(result == NULL, "otherwise we should have exited the loop earlier");
916 // So far our attempts to allocate failed. The only time we'll go
917 // around the loop and try again is if we tried to do a GC and the
918 // VM op that we tried to schedule was not successful because
919 // another thread beat us to it. That way it's possible that some
920 // space was freed up by the thread that successfully scheduled a
921 // GC. So it's worth trying to allocate again.
922 if (succeeded) {
923 break;
924 }
926 // Give a warning if we seem to be looping forever.
927 if ((QueuedAllocationWarningCount > 0) &&
928 (try_count % QueuedAllocationWarningCount == 0)) {
929 warning("G1CollectedHeap::attempt_allocation_humongous "
930 "retries %d times", try_count);
931 }
932 }
934 assert_heap_locked_or_at_safepoint();
935 return NULL;
936 }
938 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
939 bool expect_null_cur_alloc_region) {
940 assert_at_safepoint();
941 assert(_cur_alloc_region == NULL || !expect_null_cur_alloc_region,
942 err_msg("the current alloc region was unexpectedly found "
943 "to be non-NULL, cur alloc region: "PTR_FORMAT" "
944 "expect_null_cur_alloc_region: %d word_size: "SIZE_FORMAT,
945 _cur_alloc_region, expect_null_cur_alloc_region, word_size));
947 if (!isHumongous(word_size)) {
948 if (!expect_null_cur_alloc_region) {
949 HeapRegion* cur_alloc_region = _cur_alloc_region;
950 if (cur_alloc_region != NULL) {
951 // This allocate method does BOT updates and we don't need them in
952 // the young generation. This will be fixed in the near future by
953 // CR 6994297.
954 HeapWord* result = cur_alloc_region->allocate(word_size);
955 if (result != NULL) {
956 assert(is_in(result), "result should be in the heap");
958 // We will not do any dirtying here. This is guaranteed to be
959 // called during a safepoint and the thread that scheduled the
960 // pause will do the dirtying if we return a non-NULL result.
961 return result;
962 }
964 retire_cur_alloc_region_common(cur_alloc_region);
965 }
966 }
968 assert(_cur_alloc_region == NULL,
969 "at this point we should have no cur alloc region");
970 return replace_cur_alloc_region_and_allocate(word_size,
971 true, /* at_safepoint */
972 false /* do_dirtying */,
973 false /* can_expand */);
974 } else {
975 return attempt_allocation_humongous(word_size,
976 true /* at_safepoint */);
977 }
979 ShouldNotReachHere();
980 }
982 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
983 assert_heap_not_locked_and_not_at_safepoint();
984 assert(!isHumongous(word_size), "we do not allow TLABs of humongous size");
986 Heap_lock->lock();
988 // First attempt: try allocating out of the current alloc region or
989 // after replacing the current alloc region.
990 HeapWord* result = attempt_allocation(word_size);
991 if (result != NULL) {
992 assert_heap_not_locked();
993 return result;
994 }
996 assert_heap_locked();
998 // Second attempt: go into the even slower path where we might
999 // try to schedule a collection.
1000 result = attempt_allocation_slow(word_size);
1001 if (result != NULL) {
1002 assert_heap_not_locked();
1003 return result;
1004 }
1006 assert_heap_locked();
1007 Heap_lock->unlock();
1008 return NULL;
1009 }
1011 HeapWord*
1012 G1CollectedHeap::mem_allocate(size_t word_size,
1013 bool is_noref,
1014 bool is_tlab,
1015 bool* gc_overhead_limit_was_exceeded) {
1016 assert_heap_not_locked_and_not_at_safepoint();
1017 assert(!is_tlab, "mem_allocate() this should not be called directly "
1018 "to allocate TLABs");
1020 // Loop until the allocation is satisified,
1021 // or unsatisfied after GC.
1022 for (int try_count = 1; /* we'll return */; try_count += 1) {
1023 unsigned int gc_count_before;
1024 {
1025 Heap_lock->lock();
1027 if (!isHumongous(word_size)) {
1028 // First attempt: try allocating out of the current alloc
1029 // region or after replacing the current alloc region.
1030 HeapWord* result = attempt_allocation(word_size);
1031 if (result != NULL) {
1032 assert_heap_not_locked();
1033 return result;
1034 }
1036 assert_heap_locked();
1038 // Second attempt: go into the even slower path where we might
1039 // try to schedule a collection.
1040 result = attempt_allocation_slow(word_size);
1041 if (result != NULL) {
1042 assert_heap_not_locked();
1043 return result;
1044 }
1045 } else {
1046 HeapWord* result = attempt_allocation_humongous(word_size,
1047 false /* at_safepoint */);
1048 if (result != NULL) {
1049 assert_heap_not_locked();
1050 return result;
1051 }
1052 }
1054 assert_heap_locked();
1055 // Read the gc count while the heap lock is held.
1056 gc_count_before = SharedHeap::heap()->total_collections();
1057 // We cannot be at a safepoint, so it is safe to unlock the Heap_lock
1058 Heap_lock->unlock();
1059 }
1061 // Create the garbage collection operation...
1062 VM_G1CollectForAllocation op(gc_count_before, word_size);
1063 // ...and get the VM thread to execute it.
1064 VMThread::execute(&op);
1066 assert_heap_not_locked();
1067 if (op.prologue_succeeded() && op.pause_succeeded()) {
1068 // If the operation was successful we'll return the result even
1069 // if it is NULL. If the allocation attempt failed immediately
1070 // after a Full GC, it's unlikely we'll be able to allocate now.
1071 HeapWord* result = op.result();
1072 if (result != NULL && !isHumongous(word_size)) {
1073 // Allocations that take place on VM operations do not do any
1074 // card dirtying and we have to do it here. We only have to do
1075 // this for non-humongous allocations, though.
1076 dirty_young_block(result, word_size);
1077 }
1078 return result;
1079 } else {
1080 assert(op.result() == NULL,
1081 "the result should be NULL if the VM op did not succeed");
1082 }
1084 // Give a warning if we seem to be looping forever.
1085 if ((QueuedAllocationWarningCount > 0) &&
1086 (try_count % QueuedAllocationWarningCount == 0)) {
1087 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
1088 }
1089 }
1091 ShouldNotReachHere();
1092 }
1094 void G1CollectedHeap::abandon_cur_alloc_region() {
1095 if (_cur_alloc_region != NULL) {
1096 // We're finished with the _cur_alloc_region.
1097 if (_cur_alloc_region->is_empty()) {
1098 _free_regions++;
1099 free_region(_cur_alloc_region);
1100 } else {
1101 // As we're builing (at least the young portion) of the collection
1102 // set incrementally we'll add the current allocation region to
1103 // the collection set here.
1104 if (_cur_alloc_region->is_young()) {
1105 g1_policy()->add_region_to_incremental_cset_lhs(_cur_alloc_region);
1106 }
1107 _summary_bytes_used += _cur_alloc_region->used();
1108 }
1109 _cur_alloc_region = NULL;
1110 }
1111 }
1113 void G1CollectedHeap::abandon_gc_alloc_regions() {
1114 // first, make sure that the GC alloc region list is empty (it should!)
1115 assert(_gc_alloc_region_list == NULL, "invariant");
1116 release_gc_alloc_regions(true /* totally */);
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(int i) {
1182 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1183 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1184 HeapRegion::RebuildRSClaimValue);
1185 }
1186 };
1188 bool G1CollectedHeap::do_collection(bool explicit_gc,
1189 bool clear_all_soft_refs,
1190 size_t word_size) {
1191 if (GC_locker::check_active_before_gc()) {
1192 return false;
1193 }
1195 SvcGCMarker sgcm(SvcGCMarker::FULL);
1196 ResourceMark rm;
1198 if (PrintHeapAtGC) {
1199 Universe::print_heap_before_gc();
1200 }
1202 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1203 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
1205 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1206 collector_policy()->should_clear_all_soft_refs();
1208 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1210 {
1211 IsGCActiveMark x;
1213 // Timing
1214 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1215 assert(!system_gc || explicit_gc, "invariant");
1216 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1217 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1218 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1219 PrintGC, true, gclog_or_tty);
1221 TraceMemoryManagerStats tms(true /* fullGC */);
1223 double start = os::elapsedTime();
1224 g1_policy()->record_full_collection_start();
1226 gc_prologue(true);
1227 increment_total_collections(true /* full gc */);
1229 size_t g1h_prev_used = used();
1230 assert(used() == recalculate_used(), "Should be equal");
1232 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1233 HandleMark hm; // Discard invalid handles created during verification
1234 prepare_for_verify();
1235 gclog_or_tty->print(" VerifyBeforeGC:");
1236 Universe::verify(true);
1237 }
1238 assert(regions_accounted_for(), "Region leakage!");
1240 COMPILER2_PRESENT(DerivedPointerTable::clear());
1242 // We want to discover references, but not process them yet.
1243 // This mode is disabled in
1244 // instanceRefKlass::process_discovered_references if the
1245 // generation does some collection work, or
1246 // instanceRefKlass::enqueue_discovered_references if the
1247 // generation returns without doing any work.
1248 ref_processor()->disable_discovery();
1249 ref_processor()->abandon_partial_discovery();
1250 ref_processor()->verify_no_references_recorded();
1252 // Abandon current iterations of concurrent marking and concurrent
1253 // refinement, if any are in progress.
1254 concurrent_mark()->abort();
1256 // Make sure we'll choose a new allocation region afterwards.
1257 abandon_cur_alloc_region();
1258 abandon_gc_alloc_regions();
1259 assert(_cur_alloc_region == NULL, "Invariant.");
1260 g1_rem_set()->cleanupHRRS();
1261 tear_down_region_lists();
1262 set_used_regions_to_need_zero_fill();
1264 // We may have added regions to the current incremental collection
1265 // set between the last GC or pause and now. We need to clear the
1266 // incremental collection set and then start rebuilding it afresh
1267 // after this full GC.
1268 abandon_collection_set(g1_policy()->inc_cset_head());
1269 g1_policy()->clear_incremental_cset();
1270 g1_policy()->stop_incremental_cset_building();
1272 if (g1_policy()->in_young_gc_mode()) {
1273 empty_young_list();
1274 g1_policy()->set_full_young_gcs(true);
1275 }
1277 // See the comment in G1CollectedHeap::ref_processing_init() about
1278 // how reference processing currently works in G1.
1280 // Temporarily make reference _discovery_ single threaded (non-MT).
1281 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
1283 // Temporarily make refs discovery atomic
1284 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
1286 // Temporarily clear _is_alive_non_header
1287 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
1289 ref_processor()->enable_discovery();
1290 ref_processor()->setup_policy(do_clear_all_soft_refs);
1292 // Do collection work
1293 {
1294 HandleMark hm; // Discard invalid handles created during gc
1295 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
1296 }
1297 // Because freeing humongous regions may have added some unclean
1298 // regions, it is necessary to tear down again before rebuilding.
1299 tear_down_region_lists();
1300 rebuild_region_lists();
1302 _summary_bytes_used = recalculate_used();
1304 ref_processor()->enqueue_discovered_references();
1306 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1308 MemoryService::track_memory_usage();
1310 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1311 HandleMark hm; // Discard invalid handles created during verification
1312 gclog_or_tty->print(" VerifyAfterGC:");
1313 prepare_for_verify();
1314 Universe::verify(false);
1315 }
1316 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1318 reset_gc_time_stamp();
1319 // Since everything potentially moved, we will clear all remembered
1320 // sets, and clear all cards. Later we will rebuild remebered
1321 // sets. We will also reset the GC time stamps of the regions.
1322 PostMCRemSetClearClosure rs_clear(mr_bs());
1323 heap_region_iterate(&rs_clear);
1325 // Resize the heap if necessary.
1326 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1328 if (_cg1r->use_cache()) {
1329 _cg1r->clear_and_record_card_counts();
1330 _cg1r->clear_hot_cache();
1331 }
1333 // Rebuild remembered sets of all regions.
1335 if (G1CollectedHeap::use_parallel_gc_threads()) {
1336 ParRebuildRSTask rebuild_rs_task(this);
1337 assert(check_heap_region_claim_values(
1338 HeapRegion::InitialClaimValue), "sanity check");
1339 set_par_threads(workers()->total_workers());
1340 workers()->run_task(&rebuild_rs_task);
1341 set_par_threads(0);
1342 assert(check_heap_region_claim_values(
1343 HeapRegion::RebuildRSClaimValue), "sanity check");
1344 reset_heap_region_claim_values();
1345 } else {
1346 RebuildRSOutOfRegionClosure rebuild_rs(this);
1347 heap_region_iterate(&rebuild_rs);
1348 }
1350 if (PrintGC) {
1351 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1352 }
1354 if (true) { // FIXME
1355 // Ask the permanent generation to adjust size for full collections
1356 perm()->compute_new_size();
1357 }
1359 // Start a new incremental collection set for the next pause
1360 assert(g1_policy()->collection_set() == NULL, "must be");
1361 g1_policy()->start_incremental_cset_building();
1363 // Clear the _cset_fast_test bitmap in anticipation of adding
1364 // regions to the incremental collection set for the next
1365 // evacuation pause.
1366 clear_cset_fast_test();
1368 double end = os::elapsedTime();
1369 g1_policy()->record_full_collection_end();
1371 #ifdef TRACESPINNING
1372 ParallelTaskTerminator::print_termination_counts();
1373 #endif
1375 gc_epilogue(true);
1377 // Discard all rset updates
1378 JavaThread::dirty_card_queue_set().abandon_logs();
1379 assert(!G1DeferredRSUpdate
1380 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1381 assert(regions_accounted_for(), "Region leakage!");
1382 }
1384 if (g1_policy()->in_young_gc_mode()) {
1385 _young_list->reset_sampled_info();
1386 // At this point there should be no regions in the
1387 // entire heap tagged as young.
1388 assert( check_young_list_empty(true /* check_heap */),
1389 "young list should be empty at this point");
1390 }
1392 // Update the number of full collections that have been completed.
1393 increment_full_collections_completed(false /* concurrent */);
1395 if (PrintHeapAtGC) {
1396 Universe::print_heap_after_gc();
1397 }
1399 return true;
1400 }
1402 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1403 // do_collection() will return whether it succeeded in performing
1404 // the GC. Currently, there is no facility on the
1405 // do_full_collection() API to notify the caller than the collection
1406 // did not succeed (e.g., because it was locked out by the GC
1407 // locker). So, right now, we'll ignore the return value.
1408 bool dummy = do_collection(true, /* explicit_gc */
1409 clear_all_soft_refs,
1410 0 /* word_size */);
1411 }
1413 // This code is mostly copied from TenuredGeneration.
1414 void
1415 G1CollectedHeap::
1416 resize_if_necessary_after_full_collection(size_t word_size) {
1417 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1419 // Include the current allocation, if any, and bytes that will be
1420 // pre-allocated to support collections, as "used".
1421 const size_t used_after_gc = used();
1422 const size_t capacity_after_gc = capacity();
1423 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1425 // This is enforced in arguments.cpp.
1426 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1427 "otherwise the code below doesn't make sense");
1429 // We don't have floating point command-line arguments
1430 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1431 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1432 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1433 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1435 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1436 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1438 // We have to be careful here as these two calculations can overflow
1439 // 32-bit size_t's.
1440 double used_after_gc_d = (double) used_after_gc;
1441 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1442 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1444 // Let's make sure that they are both under the max heap size, which
1445 // by default will make them fit into a size_t.
1446 double desired_capacity_upper_bound = (double) max_heap_size;
1447 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1448 desired_capacity_upper_bound);
1449 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1450 desired_capacity_upper_bound);
1452 // We can now safely turn them into size_t's.
1453 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1454 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1456 // This assert only makes sense here, before we adjust them
1457 // with respect to the min and max heap size.
1458 assert(minimum_desired_capacity <= maximum_desired_capacity,
1459 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1460 "maximum_desired_capacity = "SIZE_FORMAT,
1461 minimum_desired_capacity, maximum_desired_capacity));
1463 // Should not be greater than the heap max size. No need to adjust
1464 // it with respect to the heap min size as it's a lower bound (i.e.,
1465 // we'll try to make the capacity larger than it, not smaller).
1466 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1467 // Should not be less than the heap min size. No need to adjust it
1468 // with respect to the heap max size as it's an upper bound (i.e.,
1469 // we'll try to make the capacity smaller than it, not greater).
1470 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1472 if (PrintGC && Verbose) {
1473 const double free_percentage =
1474 (double) free_after_gc / (double) capacity_after_gc;
1475 gclog_or_tty->print_cr("Computing new size after full GC ");
1476 gclog_or_tty->print_cr(" "
1477 " minimum_free_percentage: %6.2f",
1478 minimum_free_percentage);
1479 gclog_or_tty->print_cr(" "
1480 " maximum_free_percentage: %6.2f",
1481 maximum_free_percentage);
1482 gclog_or_tty->print_cr(" "
1483 " capacity: %6.1fK"
1484 " minimum_desired_capacity: %6.1fK"
1485 " maximum_desired_capacity: %6.1fK",
1486 (double) capacity_after_gc / (double) K,
1487 (double) minimum_desired_capacity / (double) K,
1488 (double) maximum_desired_capacity / (double) K);
1489 gclog_or_tty->print_cr(" "
1490 " free_after_gc: %6.1fK"
1491 " used_after_gc: %6.1fK",
1492 (double) free_after_gc / (double) K,
1493 (double) used_after_gc / (double) K);
1494 gclog_or_tty->print_cr(" "
1495 " free_percentage: %6.2f",
1496 free_percentage);
1497 }
1498 if (capacity_after_gc < minimum_desired_capacity) {
1499 // Don't expand unless it's significant
1500 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1501 expand(expand_bytes);
1502 if (PrintGC && Verbose) {
1503 gclog_or_tty->print_cr(" "
1504 " expanding:"
1505 " max_heap_size: %6.1fK"
1506 " minimum_desired_capacity: %6.1fK"
1507 " expand_bytes: %6.1fK",
1508 (double) max_heap_size / (double) K,
1509 (double) minimum_desired_capacity / (double) K,
1510 (double) expand_bytes / (double) K);
1511 }
1513 // No expansion, now see if we want to shrink
1514 } else if (capacity_after_gc > maximum_desired_capacity) {
1515 // Capacity too large, compute shrinking size
1516 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1517 shrink(shrink_bytes);
1518 if (PrintGC && Verbose) {
1519 gclog_or_tty->print_cr(" "
1520 " shrinking:"
1521 " min_heap_size: %6.1fK"
1522 " maximum_desired_capacity: %6.1fK"
1523 " shrink_bytes: %6.1fK",
1524 (double) min_heap_size / (double) K,
1525 (double) maximum_desired_capacity / (double) K,
1526 (double) shrink_bytes / (double) K);
1527 }
1528 }
1529 }
1532 HeapWord*
1533 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1534 bool* succeeded) {
1535 assert(SafepointSynchronize::is_at_safepoint(),
1536 "satisfy_failed_allocation() should only be called at a safepoint");
1537 assert(Thread::current()->is_VM_thread(),
1538 "satisfy_failed_allocation() should only be called by the VM thread");
1540 *succeeded = true;
1541 // Let's attempt the allocation first.
1542 HeapWord* result = attempt_allocation_at_safepoint(word_size,
1543 false /* expect_null_cur_alloc_region */);
1544 if (result != NULL) {
1545 assert(*succeeded, "sanity");
1546 return result;
1547 }
1549 // In a G1 heap, we're supposed to keep allocation from failing by
1550 // incremental pauses. Therefore, at least for now, we'll favor
1551 // expansion over collection. (This might change in the future if we can
1552 // do something smarter than full collection to satisfy a failed alloc.)
1553 result = expand_and_allocate(word_size);
1554 if (result != NULL) {
1555 assert(*succeeded, "sanity");
1556 return result;
1557 }
1559 // Expansion didn't work, we'll try to do a Full GC.
1560 bool gc_succeeded = do_collection(false, /* explicit_gc */
1561 false, /* clear_all_soft_refs */
1562 word_size);
1563 if (!gc_succeeded) {
1564 *succeeded = false;
1565 return NULL;
1566 }
1568 // Retry the allocation
1569 result = attempt_allocation_at_safepoint(word_size,
1570 true /* expect_null_cur_alloc_region */);
1571 if (result != NULL) {
1572 assert(*succeeded, "sanity");
1573 return result;
1574 }
1576 // Then, try a Full GC that will collect all soft references.
1577 gc_succeeded = do_collection(false, /* explicit_gc */
1578 true, /* clear_all_soft_refs */
1579 word_size);
1580 if (!gc_succeeded) {
1581 *succeeded = false;
1582 return NULL;
1583 }
1585 // Retry the allocation once more
1586 result = attempt_allocation_at_safepoint(word_size,
1587 true /* expect_null_cur_alloc_region */);
1588 if (result != NULL) {
1589 assert(*succeeded, "sanity");
1590 return result;
1591 }
1593 assert(!collector_policy()->should_clear_all_soft_refs(),
1594 "Flag should have been handled and cleared prior to this point");
1596 // What else? We might try synchronous finalization later. If the total
1597 // space available is large enough for the allocation, then a more
1598 // complete compaction phase than we've tried so far might be
1599 // appropriate.
1600 assert(*succeeded, "sanity");
1601 return NULL;
1602 }
1604 // Attempting to expand the heap sufficiently
1605 // to support an allocation of the given "word_size". If
1606 // successful, perform the allocation and return the address of the
1607 // allocated block, or else "NULL".
1609 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1610 assert(SafepointSynchronize::is_at_safepoint(),
1611 "expand_and_allocate() should only be called at a safepoint");
1612 assert(Thread::current()->is_VM_thread(),
1613 "expand_and_allocate() should only be called by the VM thread");
1615 size_t expand_bytes = word_size * HeapWordSize;
1616 if (expand_bytes < MinHeapDeltaBytes) {
1617 expand_bytes = MinHeapDeltaBytes;
1618 }
1619 expand(expand_bytes);
1620 assert(regions_accounted_for(), "Region leakage!");
1622 return attempt_allocation_at_safepoint(word_size,
1623 false /* expect_null_cur_alloc_region */);
1624 }
1626 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1627 size_t pre_used = 0;
1628 size_t cleared_h_regions = 0;
1629 size_t freed_regions = 0;
1630 UncleanRegionList local_list;
1631 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1632 freed_regions, &local_list);
1634 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1635 &local_list);
1636 return pre_used;
1637 }
1639 void
1640 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1641 size_t& pre_used,
1642 size_t& cleared_h,
1643 size_t& freed_regions,
1644 UncleanRegionList* list,
1645 bool par) {
1646 assert(!hr->continuesHumongous(), "should have filtered these out");
1647 size_t res = 0;
1648 if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
1649 !hr->is_young()) {
1650 if (G1PolicyVerbose > 0)
1651 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1652 " during cleanup", hr, hr->used());
1653 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1654 }
1655 }
1657 // FIXME: both this and shrink could probably be more efficient by
1658 // doing one "VirtualSpace::expand_by" call rather than several.
1659 void G1CollectedHeap::expand(size_t expand_bytes) {
1660 size_t old_mem_size = _g1_storage.committed_size();
1661 // We expand by a minimum of 1K.
1662 expand_bytes = MAX2(expand_bytes, (size_t)K);
1663 size_t aligned_expand_bytes =
1664 ReservedSpace::page_align_size_up(expand_bytes);
1665 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1666 HeapRegion::GrainBytes);
1667 expand_bytes = aligned_expand_bytes;
1668 while (expand_bytes > 0) {
1669 HeapWord* base = (HeapWord*)_g1_storage.high();
1670 // Commit more storage.
1671 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1672 if (!successful) {
1673 expand_bytes = 0;
1674 } else {
1675 expand_bytes -= HeapRegion::GrainBytes;
1676 // Expand the committed region.
1677 HeapWord* high = (HeapWord*) _g1_storage.high();
1678 _g1_committed.set_end(high);
1679 // Create a new HeapRegion.
1680 MemRegion mr(base, high);
1681 bool is_zeroed = !_g1_max_committed.contains(base);
1682 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1684 // Now update max_committed if necessary.
1685 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1687 // Add it to the HeapRegionSeq.
1688 _hrs->insert(hr);
1689 // Set the zero-fill state, according to whether it's already
1690 // zeroed.
1691 {
1692 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1693 if (is_zeroed) {
1694 hr->set_zero_fill_complete();
1695 put_free_region_on_list_locked(hr);
1696 } else {
1697 hr->set_zero_fill_needed();
1698 put_region_on_unclean_list_locked(hr);
1699 }
1700 }
1701 _free_regions++;
1702 // And we used up an expansion region to create it.
1703 _expansion_regions--;
1704 // Tell the cardtable about it.
1705 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1706 // And the offset table as well.
1707 _bot_shared->resize(_g1_committed.word_size());
1708 }
1709 }
1710 if (Verbose && PrintGC) {
1711 size_t new_mem_size = _g1_storage.committed_size();
1712 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1713 old_mem_size/K, aligned_expand_bytes/K,
1714 new_mem_size/K);
1715 }
1716 }
1718 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1719 {
1720 size_t old_mem_size = _g1_storage.committed_size();
1721 size_t aligned_shrink_bytes =
1722 ReservedSpace::page_align_size_down(shrink_bytes);
1723 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1724 HeapRegion::GrainBytes);
1725 size_t num_regions_deleted = 0;
1726 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1728 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1729 if (mr.byte_size() > 0)
1730 _g1_storage.shrink_by(mr.byte_size());
1731 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1733 _g1_committed.set_end(mr.start());
1734 _free_regions -= num_regions_deleted;
1735 _expansion_regions += num_regions_deleted;
1737 // Tell the cardtable about it.
1738 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1740 // And the offset table as well.
1741 _bot_shared->resize(_g1_committed.word_size());
1743 HeapRegionRemSet::shrink_heap(n_regions());
1745 if (Verbose && PrintGC) {
1746 size_t new_mem_size = _g1_storage.committed_size();
1747 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1748 old_mem_size/K, aligned_shrink_bytes/K,
1749 new_mem_size/K);
1750 }
1751 }
1753 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1754 release_gc_alloc_regions(true /* totally */);
1755 tear_down_region_lists(); // We will rebuild them in a moment.
1756 shrink_helper(shrink_bytes);
1757 rebuild_region_lists();
1758 }
1760 // Public methods.
1762 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1763 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1764 #endif // _MSC_VER
1767 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1768 SharedHeap(policy_),
1769 _g1_policy(policy_),
1770 _dirty_card_queue_set(false),
1771 _into_cset_dirty_card_queue_set(false),
1772 _is_alive_closure(this),
1773 _ref_processor(NULL),
1774 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1775 _bot_shared(NULL),
1776 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1777 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1778 _evac_failure_scan_stack(NULL) ,
1779 _mark_in_progress(false),
1780 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1781 _cur_alloc_region(NULL),
1782 _refine_cte_cl(NULL),
1783 _free_region_list(NULL), _free_region_list_size(0),
1784 _free_regions(0),
1785 _full_collection(false),
1786 _unclean_region_list(),
1787 _unclean_regions_coming(false),
1788 _young_list(new YoungList(this)),
1789 _gc_time_stamp(0),
1790 _surviving_young_words(NULL),
1791 _full_collections_completed(0),
1792 _in_cset_fast_test(NULL),
1793 _in_cset_fast_test_base(NULL),
1794 _dirty_cards_region_list(NULL) {
1795 _g1h = this; // To catch bugs.
1796 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1797 vm_exit_during_initialization("Failed necessary allocation.");
1798 }
1800 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1802 int n_queues = MAX2((int)ParallelGCThreads, 1);
1803 _task_queues = new RefToScanQueueSet(n_queues);
1805 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1806 assert(n_rem_sets > 0, "Invariant.");
1808 HeapRegionRemSetIterator** iter_arr =
1809 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1810 for (int i = 0; i < n_queues; i++) {
1811 iter_arr[i] = new HeapRegionRemSetIterator();
1812 }
1813 _rem_set_iterator = iter_arr;
1815 for (int i = 0; i < n_queues; i++) {
1816 RefToScanQueue* q = new RefToScanQueue();
1817 q->initialize();
1818 _task_queues->register_queue(i, q);
1819 }
1821 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1822 _gc_alloc_regions[ap] = NULL;
1823 _gc_alloc_region_counts[ap] = 0;
1824 _retained_gc_alloc_regions[ap] = NULL;
1825 // by default, we do not retain a GC alloc region for each ap;
1826 // we'll override this, when appropriate, below
1827 _retain_gc_alloc_region[ap] = false;
1828 }
1830 // We will try to remember the last half-full tenured region we
1831 // allocated to at the end of a collection so that we can re-use it
1832 // during the next collection.
1833 _retain_gc_alloc_region[GCAllocForTenured] = true;
1835 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1836 }
1838 jint G1CollectedHeap::initialize() {
1839 CollectedHeap::pre_initialize();
1840 os::enable_vtime();
1842 // Necessary to satisfy locking discipline assertions.
1844 MutexLocker x(Heap_lock);
1846 // While there are no constraints in the GC code that HeapWordSize
1847 // be any particular value, there are multiple other areas in the
1848 // system which believe this to be true (e.g. oop->object_size in some
1849 // cases incorrectly returns the size in wordSize units rather than
1850 // HeapWordSize).
1851 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1853 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1854 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1856 // Ensure that the sizes are properly aligned.
1857 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1858 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1860 _cg1r = new ConcurrentG1Refine();
1862 // Reserve the maximum.
1863 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1864 // Includes the perm-gen.
1866 const size_t total_reserved = max_byte_size + pgs->max_size();
1867 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1869 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1870 HeapRegion::GrainBytes,
1871 false /*ism*/, addr);
1873 if (UseCompressedOops) {
1874 if (addr != NULL && !heap_rs.is_reserved()) {
1875 // Failed to reserve at specified address - the requested memory
1876 // region is taken already, for example, by 'java' launcher.
1877 // Try again to reserver heap higher.
1878 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1879 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1880 false /*ism*/, addr);
1881 if (addr != NULL && !heap_rs0.is_reserved()) {
1882 // Failed to reserve at specified address again - give up.
1883 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1884 assert(addr == NULL, "");
1885 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1886 false /*ism*/, addr);
1887 heap_rs = heap_rs1;
1888 } else {
1889 heap_rs = heap_rs0;
1890 }
1891 }
1892 }
1894 if (!heap_rs.is_reserved()) {
1895 vm_exit_during_initialization("Could not reserve enough space for object heap");
1896 return JNI_ENOMEM;
1897 }
1899 // It is important to do this in a way such that concurrent readers can't
1900 // temporarily think somethings in the heap. (I've actually seen this
1901 // happen in asserts: DLD.)
1902 _reserved.set_word_size(0);
1903 _reserved.set_start((HeapWord*)heap_rs.base());
1904 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1906 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1908 _num_humongous_regions = 0;
1910 // Create the gen rem set (and barrier set) for the entire reserved region.
1911 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1912 set_barrier_set(rem_set()->bs());
1913 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1914 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1915 } else {
1916 vm_exit_during_initialization("G1 requires a mod ref bs.");
1917 return JNI_ENOMEM;
1918 }
1920 // Also create a G1 rem set.
1921 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1922 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1923 } else {
1924 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1925 return JNI_ENOMEM;
1926 }
1928 // Carve out the G1 part of the heap.
1930 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1931 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1932 g1_rs.size()/HeapWordSize);
1933 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1935 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1937 _g1_storage.initialize(g1_rs, 0);
1938 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1939 _g1_max_committed = _g1_committed;
1940 _hrs = new HeapRegionSeq(_expansion_regions);
1941 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1942 guarantee(_cur_alloc_region == NULL, "from constructor");
1944 // 6843694 - ensure that the maximum region index can fit
1945 // in the remembered set structures.
1946 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1947 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1949 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1950 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1951 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1952 "too many cards per region");
1954 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1955 heap_word_size(init_byte_size));
1957 _g1h = this;
1959 _in_cset_fast_test_length = max_regions();
1960 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
1962 // We're biasing _in_cset_fast_test to avoid subtracting the
1963 // beginning of the heap every time we want to index; basically
1964 // it's the same with what we do with the card table.
1965 _in_cset_fast_test = _in_cset_fast_test_base -
1966 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
1968 // Clear the _cset_fast_test bitmap in anticipation of adding
1969 // regions to the incremental collection set for the first
1970 // evacuation pause.
1971 clear_cset_fast_test();
1973 // Create the ConcurrentMark data structure and thread.
1974 // (Must do this late, so that "max_regions" is defined.)
1975 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1976 _cmThread = _cm->cmThread();
1978 // ...and the concurrent zero-fill thread, if necessary.
1979 if (G1ConcZeroFill) {
1980 _czft = new ConcurrentZFThread();
1981 }
1983 // Initialize the from_card cache structure of HeapRegionRemSet.
1984 HeapRegionRemSet::init_heap(max_regions());
1986 // Now expand into the initial heap size.
1987 expand(init_byte_size);
1989 // Perform any initialization actions delegated to the policy.
1990 g1_policy()->init();
1992 g1_policy()->note_start_of_mark_thread();
1994 _refine_cte_cl =
1995 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1996 g1_rem_set(),
1997 concurrent_g1_refine());
1998 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2000 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2001 SATB_Q_FL_lock,
2002 G1SATBProcessCompletedThreshold,
2003 Shared_SATB_Q_lock);
2005 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2006 DirtyCardQ_FL_lock,
2007 concurrent_g1_refine()->yellow_zone(),
2008 concurrent_g1_refine()->red_zone(),
2009 Shared_DirtyCardQ_lock);
2011 if (G1DeferredRSUpdate) {
2012 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2013 DirtyCardQ_FL_lock,
2014 -1, // never trigger processing
2015 -1, // no limit on length
2016 Shared_DirtyCardQ_lock,
2017 &JavaThread::dirty_card_queue_set());
2018 }
2020 // Initialize the card queue set used to hold cards containing
2021 // references into the collection set.
2022 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2023 DirtyCardQ_FL_lock,
2024 -1, // never trigger processing
2025 -1, // no limit on length
2026 Shared_DirtyCardQ_lock,
2027 &JavaThread::dirty_card_queue_set());
2029 // In case we're keeping closure specialization stats, initialize those
2030 // counts and that mechanism.
2031 SpecializationStats::clear();
2033 _gc_alloc_region_list = NULL;
2035 // Do later initialization work for concurrent refinement.
2036 _cg1r->init();
2038 return JNI_OK;
2039 }
2041 void G1CollectedHeap::ref_processing_init() {
2042 // Reference processing in G1 currently works as follows:
2043 //
2044 // * There is only one reference processor instance that
2045 // 'spans' the entire heap. It is created by the code
2046 // below.
2047 // * Reference discovery is not enabled during an incremental
2048 // pause (see 6484982).
2049 // * Discoverered refs are not enqueued nor are they processed
2050 // during an incremental pause (see 6484982).
2051 // * Reference discovery is enabled at initial marking.
2052 // * Reference discovery is disabled and the discovered
2053 // references processed etc during remarking.
2054 // * Reference discovery is MT (see below).
2055 // * Reference discovery requires a barrier (see below).
2056 // * Reference processing is currently not MT (see 6608385).
2057 // * A full GC enables (non-MT) reference discovery and
2058 // processes any discovered references.
2060 SharedHeap::ref_processing_init();
2061 MemRegion mr = reserved_region();
2062 _ref_processor = ReferenceProcessor::create_ref_processor(
2063 mr, // span
2064 false, // Reference discovery is not atomic
2065 true, // mt_discovery
2066 &_is_alive_closure, // is alive closure
2067 // for efficiency
2068 ParallelGCThreads,
2069 ParallelRefProcEnabled,
2070 true); // Setting next fields of discovered
2071 // lists requires a barrier.
2072 }
2074 size_t G1CollectedHeap::capacity() const {
2075 return _g1_committed.byte_size();
2076 }
2078 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2079 DirtyCardQueue* into_cset_dcq,
2080 bool concurrent,
2081 int worker_i) {
2082 // Clean cards in the hot card cache
2083 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2085 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2086 int n_completed_buffers = 0;
2087 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2088 n_completed_buffers++;
2089 }
2090 g1_policy()->record_update_rs_processed_buffers(worker_i,
2091 (double) n_completed_buffers);
2092 dcqs.clear_n_completed_buffers();
2093 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2094 }
2097 // Computes the sum of the storage used by the various regions.
2099 size_t G1CollectedHeap::used() const {
2100 assert(Heap_lock->owner() != NULL,
2101 "Should be owned on this thread's behalf.");
2102 size_t result = _summary_bytes_used;
2103 // Read only once in case it is set to NULL concurrently
2104 HeapRegion* hr = _cur_alloc_region;
2105 if (hr != NULL)
2106 result += hr->used();
2107 return result;
2108 }
2110 size_t G1CollectedHeap::used_unlocked() const {
2111 size_t result = _summary_bytes_used;
2112 return result;
2113 }
2115 class SumUsedClosure: public HeapRegionClosure {
2116 size_t _used;
2117 public:
2118 SumUsedClosure() : _used(0) {}
2119 bool doHeapRegion(HeapRegion* r) {
2120 if (!r->continuesHumongous()) {
2121 _used += r->used();
2122 }
2123 return false;
2124 }
2125 size_t result() { return _used; }
2126 };
2128 size_t G1CollectedHeap::recalculate_used() const {
2129 SumUsedClosure blk;
2130 _hrs->iterate(&blk);
2131 return blk.result();
2132 }
2134 #ifndef PRODUCT
2135 class SumUsedRegionsClosure: public HeapRegionClosure {
2136 size_t _num;
2137 public:
2138 SumUsedRegionsClosure() : _num(0) {}
2139 bool doHeapRegion(HeapRegion* r) {
2140 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
2141 _num += 1;
2142 }
2143 return false;
2144 }
2145 size_t result() { return _num; }
2146 };
2148 size_t G1CollectedHeap::recalculate_used_regions() const {
2149 SumUsedRegionsClosure blk;
2150 _hrs->iterate(&blk);
2151 return blk.result();
2152 }
2153 #endif // PRODUCT
2155 size_t G1CollectedHeap::unsafe_max_alloc() {
2156 if (_free_regions > 0) return HeapRegion::GrainBytes;
2157 // otherwise, is there space in the current allocation region?
2159 // We need to store the current allocation region in a local variable
2160 // here. The problem is that this method doesn't take any locks and
2161 // there may be other threads which overwrite the current allocation
2162 // region field. attempt_allocation(), for example, sets it to NULL
2163 // and this can happen *after* the NULL check here but before the call
2164 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2165 // to be a problem in the optimized build, since the two loads of the
2166 // current allocation region field are optimized away.
2167 HeapRegion* car = _cur_alloc_region;
2169 // FIXME: should iterate over all regions?
2170 if (car == NULL) {
2171 return 0;
2172 }
2173 return car->free();
2174 }
2176 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2177 return
2178 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2179 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2180 }
2182 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2183 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2185 // We assume that if concurrent == true, then the caller is a
2186 // concurrent thread that was joined the Suspendible Thread
2187 // Set. If there's ever a cheap way to check this, we should add an
2188 // assert here.
2190 // We have already incremented _total_full_collections at the start
2191 // of the GC, so total_full_collections() represents how many full
2192 // collections have been started.
2193 unsigned int full_collections_started = total_full_collections();
2195 // Given that this method is called at the end of a Full GC or of a
2196 // concurrent cycle, and those can be nested (i.e., a Full GC can
2197 // interrupt a concurrent cycle), the number of full collections
2198 // completed should be either one (in the case where there was no
2199 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2200 // behind the number of full collections started.
2202 // This is the case for the inner caller, i.e. a Full GC.
2203 assert(concurrent ||
2204 (full_collections_started == _full_collections_completed + 1) ||
2205 (full_collections_started == _full_collections_completed + 2),
2206 err_msg("for inner caller (Full GC): full_collections_started = %u "
2207 "is inconsistent with _full_collections_completed = %u",
2208 full_collections_started, _full_collections_completed));
2210 // This is the case for the outer caller, i.e. the concurrent cycle.
2211 assert(!concurrent ||
2212 (full_collections_started == _full_collections_completed + 1),
2213 err_msg("for outer caller (concurrent cycle): "
2214 "full_collections_started = %u "
2215 "is inconsistent with _full_collections_completed = %u",
2216 full_collections_started, _full_collections_completed));
2218 _full_collections_completed += 1;
2220 // We need to clear the "in_progress" flag in the CM thread before
2221 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2222 // is set) so that if a waiter requests another System.gc() it doesn't
2223 // incorrectly see that a marking cyle is still in progress.
2224 if (concurrent) {
2225 _cmThread->clear_in_progress();
2226 }
2228 // This notify_all() will ensure that a thread that called
2229 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2230 // and it's waiting for a full GC to finish will be woken up. It is
2231 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2232 FullGCCount_lock->notify_all();
2233 }
2235 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2236 assert(Thread::current()->is_VM_thread(), "Precondition#1");
2237 assert(Heap_lock->is_locked(), "Precondition#2");
2238 GCCauseSetter gcs(this, cause);
2239 switch (cause) {
2240 case GCCause::_heap_inspection:
2241 case GCCause::_heap_dump: {
2242 HandleMark hm;
2243 do_full_collection(false); // don't clear all soft refs
2244 break;
2245 }
2246 default: // XXX FIX ME
2247 ShouldNotReachHere(); // Unexpected use of this function
2248 }
2249 }
2251 void G1CollectedHeap::collect(GCCause::Cause cause) {
2252 // The caller doesn't have the Heap_lock
2253 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2255 unsigned int gc_count_before;
2256 unsigned int full_gc_count_before;
2257 {
2258 MutexLocker ml(Heap_lock);
2260 // Don't want to do a GC until cleanup is completed. This
2261 // limitation will be removed in the near future when the
2262 // operation of the free region list is revamped as part of
2263 // CR 6977804.
2264 wait_for_cleanup_complete();
2266 // Read the GC count while holding the Heap_lock
2267 gc_count_before = SharedHeap::heap()->total_collections();
2268 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2269 }
2271 if (should_do_concurrent_full_gc(cause)) {
2272 // Schedule an initial-mark evacuation pause that will start a
2273 // concurrent cycle. We're setting word_size to 0 which means that
2274 // we are not requesting a post-GC allocation.
2275 VM_G1IncCollectionPause op(gc_count_before,
2276 0, /* word_size */
2277 true, /* should_initiate_conc_mark */
2278 g1_policy()->max_pause_time_ms(),
2279 cause);
2280 VMThread::execute(&op);
2281 } else {
2282 if (cause == GCCause::_gc_locker
2283 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2285 // Schedule a standard evacuation pause. We're setting word_size
2286 // to 0 which means that we are not requesting a post-GC allocation.
2287 VM_G1IncCollectionPause op(gc_count_before,
2288 0, /* word_size */
2289 false, /* should_initiate_conc_mark */
2290 g1_policy()->max_pause_time_ms(),
2291 cause);
2292 VMThread::execute(&op);
2293 } else {
2294 // Schedule a Full GC.
2295 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2296 VMThread::execute(&op);
2297 }
2298 }
2299 }
2301 bool G1CollectedHeap::is_in(const void* p) const {
2302 if (_g1_committed.contains(p)) {
2303 HeapRegion* hr = _hrs->addr_to_region(p);
2304 return hr->is_in(p);
2305 } else {
2306 return _perm_gen->as_gen()->is_in(p);
2307 }
2308 }
2310 // Iteration functions.
2312 // Iterates an OopClosure over all ref-containing fields of objects
2313 // within a HeapRegion.
2315 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2316 MemRegion _mr;
2317 OopClosure* _cl;
2318 public:
2319 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2320 : _mr(mr), _cl(cl) {}
2321 bool doHeapRegion(HeapRegion* r) {
2322 if (! r->continuesHumongous()) {
2323 r->oop_iterate(_cl);
2324 }
2325 return false;
2326 }
2327 };
2329 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2330 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2331 _hrs->iterate(&blk);
2332 if (do_perm) {
2333 perm_gen()->oop_iterate(cl);
2334 }
2335 }
2337 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2338 IterateOopClosureRegionClosure blk(mr, cl);
2339 _hrs->iterate(&blk);
2340 if (do_perm) {
2341 perm_gen()->oop_iterate(cl);
2342 }
2343 }
2345 // Iterates an ObjectClosure over all objects within a HeapRegion.
2347 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2348 ObjectClosure* _cl;
2349 public:
2350 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2351 bool doHeapRegion(HeapRegion* r) {
2352 if (! r->continuesHumongous()) {
2353 r->object_iterate(_cl);
2354 }
2355 return false;
2356 }
2357 };
2359 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2360 IterateObjectClosureRegionClosure blk(cl);
2361 _hrs->iterate(&blk);
2362 if (do_perm) {
2363 perm_gen()->object_iterate(cl);
2364 }
2365 }
2367 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2368 // FIXME: is this right?
2369 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2370 }
2372 // Calls a SpaceClosure on a HeapRegion.
2374 class SpaceClosureRegionClosure: public HeapRegionClosure {
2375 SpaceClosure* _cl;
2376 public:
2377 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2378 bool doHeapRegion(HeapRegion* r) {
2379 _cl->do_space(r);
2380 return false;
2381 }
2382 };
2384 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2385 SpaceClosureRegionClosure blk(cl);
2386 _hrs->iterate(&blk);
2387 }
2389 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
2390 _hrs->iterate(cl);
2391 }
2393 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2394 HeapRegionClosure* cl) {
2395 _hrs->iterate_from(r, cl);
2396 }
2398 void
2399 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
2400 _hrs->iterate_from(idx, cl);
2401 }
2403 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
2405 void
2406 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2407 int worker,
2408 jint claim_value) {
2409 const size_t regions = n_regions();
2410 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
2411 // try to spread out the starting points of the workers
2412 const size_t start_index = regions / worker_num * (size_t) worker;
2414 // each worker will actually look at all regions
2415 for (size_t count = 0; count < regions; ++count) {
2416 const size_t index = (start_index + count) % regions;
2417 assert(0 <= index && index < regions, "sanity");
2418 HeapRegion* r = region_at(index);
2419 // we'll ignore "continues humongous" regions (we'll process them
2420 // when we come across their corresponding "start humongous"
2421 // region) and regions already claimed
2422 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2423 continue;
2424 }
2425 // OK, try to claim it
2426 if (r->claimHeapRegion(claim_value)) {
2427 // success!
2428 assert(!r->continuesHumongous(), "sanity");
2429 if (r->startsHumongous()) {
2430 // If the region is "starts humongous" we'll iterate over its
2431 // "continues humongous" first; in fact we'll do them
2432 // first. The order is important. In on case, calling the
2433 // closure on the "starts humongous" region might de-allocate
2434 // and clear all its "continues humongous" regions and, as a
2435 // result, we might end up processing them twice. So, we'll do
2436 // them first (notice: most closures will ignore them anyway) and
2437 // then we'll do the "starts humongous" region.
2438 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2439 HeapRegion* chr = region_at(ch_index);
2441 // if the region has already been claimed or it's not
2442 // "continues humongous" we're done
2443 if (chr->claim_value() == claim_value ||
2444 !chr->continuesHumongous()) {
2445 break;
2446 }
2448 // Noone should have claimed it directly. We can given
2449 // that we claimed its "starts humongous" region.
2450 assert(chr->claim_value() != claim_value, "sanity");
2451 assert(chr->humongous_start_region() == r, "sanity");
2453 if (chr->claimHeapRegion(claim_value)) {
2454 // we should always be able to claim it; noone else should
2455 // be trying to claim this region
2457 bool res2 = cl->doHeapRegion(chr);
2458 assert(!res2, "Should not abort");
2460 // Right now, this holds (i.e., no closure that actually
2461 // does something with "continues humongous" regions
2462 // clears them). We might have to weaken it in the future,
2463 // but let's leave these two asserts here for extra safety.
2464 assert(chr->continuesHumongous(), "should still be the case");
2465 assert(chr->humongous_start_region() == r, "sanity");
2466 } else {
2467 guarantee(false, "we should not reach here");
2468 }
2469 }
2470 }
2472 assert(!r->continuesHumongous(), "sanity");
2473 bool res = cl->doHeapRegion(r);
2474 assert(!res, "Should not abort");
2475 }
2476 }
2477 }
2479 class ResetClaimValuesClosure: public HeapRegionClosure {
2480 public:
2481 bool doHeapRegion(HeapRegion* r) {
2482 r->set_claim_value(HeapRegion::InitialClaimValue);
2483 return false;
2484 }
2485 };
2487 void
2488 G1CollectedHeap::reset_heap_region_claim_values() {
2489 ResetClaimValuesClosure blk;
2490 heap_region_iterate(&blk);
2491 }
2493 #ifdef ASSERT
2494 // This checks whether all regions in the heap have the correct claim
2495 // value. I also piggy-backed on this a check to ensure that the
2496 // humongous_start_region() information on "continues humongous"
2497 // regions is correct.
2499 class CheckClaimValuesClosure : public HeapRegionClosure {
2500 private:
2501 jint _claim_value;
2502 size_t _failures;
2503 HeapRegion* _sh_region;
2504 public:
2505 CheckClaimValuesClosure(jint claim_value) :
2506 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2507 bool doHeapRegion(HeapRegion* r) {
2508 if (r->claim_value() != _claim_value) {
2509 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2510 "claim value = %d, should be %d",
2511 r->bottom(), r->end(), r->claim_value(),
2512 _claim_value);
2513 ++_failures;
2514 }
2515 if (!r->isHumongous()) {
2516 _sh_region = NULL;
2517 } else if (r->startsHumongous()) {
2518 _sh_region = r;
2519 } else if (r->continuesHumongous()) {
2520 if (r->humongous_start_region() != _sh_region) {
2521 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2522 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2523 r->bottom(), r->end(),
2524 r->humongous_start_region(),
2525 _sh_region);
2526 ++_failures;
2527 }
2528 }
2529 return false;
2530 }
2531 size_t failures() {
2532 return _failures;
2533 }
2534 };
2536 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2537 CheckClaimValuesClosure cl(claim_value);
2538 heap_region_iterate(&cl);
2539 return cl.failures() == 0;
2540 }
2541 #endif // ASSERT
2543 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2544 HeapRegion* r = g1_policy()->collection_set();
2545 while (r != NULL) {
2546 HeapRegion* next = r->next_in_collection_set();
2547 if (cl->doHeapRegion(r)) {
2548 cl->incomplete();
2549 return;
2550 }
2551 r = next;
2552 }
2553 }
2555 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2556 HeapRegionClosure *cl) {
2557 if (r == NULL) {
2558 // The CSet is empty so there's nothing to do.
2559 return;
2560 }
2562 assert(r->in_collection_set(),
2563 "Start region must be a member of the collection set.");
2564 HeapRegion* cur = r;
2565 while (cur != NULL) {
2566 HeapRegion* next = cur->next_in_collection_set();
2567 if (cl->doHeapRegion(cur) && false) {
2568 cl->incomplete();
2569 return;
2570 }
2571 cur = next;
2572 }
2573 cur = g1_policy()->collection_set();
2574 while (cur != r) {
2575 HeapRegion* next = cur->next_in_collection_set();
2576 if (cl->doHeapRegion(cur) && false) {
2577 cl->incomplete();
2578 return;
2579 }
2580 cur = next;
2581 }
2582 }
2584 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2585 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2586 }
2589 Space* G1CollectedHeap::space_containing(const void* addr) const {
2590 Space* res = heap_region_containing(addr);
2591 if (res == NULL)
2592 res = perm_gen()->space_containing(addr);
2593 return res;
2594 }
2596 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2597 Space* sp = space_containing(addr);
2598 if (sp != NULL) {
2599 return sp->block_start(addr);
2600 }
2601 return NULL;
2602 }
2604 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2605 Space* sp = space_containing(addr);
2606 assert(sp != NULL, "block_size of address outside of heap");
2607 return sp->block_size(addr);
2608 }
2610 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2611 Space* sp = space_containing(addr);
2612 return sp->block_is_obj(addr);
2613 }
2615 bool G1CollectedHeap::supports_tlab_allocation() const {
2616 return true;
2617 }
2619 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2620 return HeapRegion::GrainBytes;
2621 }
2623 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2624 // Return the remaining space in the cur alloc region, but not less than
2625 // the min TLAB size.
2627 // Also, this value can be at most the humongous object threshold,
2628 // since we can't allow tlabs to grow big enough to accomodate
2629 // humongous objects.
2631 // We need to store the cur alloc region locally, since it might change
2632 // between when we test for NULL and when we use it later.
2633 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2634 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2636 if (cur_alloc_space == NULL) {
2637 return max_tlab_size;
2638 } else {
2639 return MIN2(MAX2(cur_alloc_space->free(), (size_t)MinTLABSize),
2640 max_tlab_size);
2641 }
2642 }
2644 bool G1CollectedHeap::allocs_are_zero_filled() {
2645 return false;
2646 }
2648 size_t G1CollectedHeap::large_typearray_limit() {
2649 // FIXME
2650 return HeapRegion::GrainBytes/HeapWordSize;
2651 }
2653 size_t G1CollectedHeap::max_capacity() const {
2654 return g1_reserved_obj_bytes();
2655 }
2657 jlong G1CollectedHeap::millis_since_last_gc() {
2658 // assert(false, "NYI");
2659 return 0;
2660 }
2663 void G1CollectedHeap::prepare_for_verify() {
2664 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2665 ensure_parsability(false);
2666 }
2667 g1_rem_set()->prepare_for_verify();
2668 }
2670 class VerifyLivenessOopClosure: public OopClosure {
2671 G1CollectedHeap* g1h;
2672 public:
2673 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2674 g1h = _g1h;
2675 }
2676 void do_oop(narrowOop *p) { do_oop_work(p); }
2677 void do_oop( oop *p) { do_oop_work(p); }
2679 template <class T> void do_oop_work(T *p) {
2680 oop obj = oopDesc::load_decode_heap_oop(p);
2681 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2682 "Dead object referenced by a not dead object");
2683 }
2684 };
2686 class VerifyObjsInRegionClosure: public ObjectClosure {
2687 private:
2688 G1CollectedHeap* _g1h;
2689 size_t _live_bytes;
2690 HeapRegion *_hr;
2691 bool _use_prev_marking;
2692 public:
2693 // use_prev_marking == true -> use "prev" marking information,
2694 // use_prev_marking == false -> use "next" marking information
2695 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2696 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2697 _g1h = G1CollectedHeap::heap();
2698 }
2699 void do_object(oop o) {
2700 VerifyLivenessOopClosure isLive(_g1h);
2701 assert(o != NULL, "Huh?");
2702 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2703 o->oop_iterate(&isLive);
2704 if (!_hr->obj_allocated_since_prev_marking(o)) {
2705 size_t obj_size = o->size(); // Make sure we don't overflow
2706 _live_bytes += (obj_size * HeapWordSize);
2707 }
2708 }
2709 }
2710 size_t live_bytes() { return _live_bytes; }
2711 };
2713 class PrintObjsInRegionClosure : public ObjectClosure {
2714 HeapRegion *_hr;
2715 G1CollectedHeap *_g1;
2716 public:
2717 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2718 _g1 = G1CollectedHeap::heap();
2719 };
2721 void do_object(oop o) {
2722 if (o != NULL) {
2723 HeapWord *start = (HeapWord *) o;
2724 size_t word_sz = o->size();
2725 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2726 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2727 (void*) o, word_sz,
2728 _g1->isMarkedPrev(o),
2729 _g1->isMarkedNext(o),
2730 _hr->obj_allocated_since_prev_marking(o));
2731 HeapWord *end = start + word_sz;
2732 HeapWord *cur;
2733 int *val;
2734 for (cur = start; cur < end; cur++) {
2735 val = (int *) cur;
2736 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2737 }
2738 }
2739 }
2740 };
2742 class VerifyRegionClosure: public HeapRegionClosure {
2743 private:
2744 bool _allow_dirty;
2745 bool _par;
2746 bool _use_prev_marking;
2747 bool _failures;
2748 public:
2749 // use_prev_marking == true -> use "prev" marking information,
2750 // use_prev_marking == false -> use "next" marking information
2751 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2752 : _allow_dirty(allow_dirty),
2753 _par(par),
2754 _use_prev_marking(use_prev_marking),
2755 _failures(false) {}
2757 bool failures() {
2758 return _failures;
2759 }
2761 bool doHeapRegion(HeapRegion* r) {
2762 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2763 "Should be unclaimed at verify points.");
2764 if (!r->continuesHumongous()) {
2765 bool failures = false;
2766 r->verify(_allow_dirty, _use_prev_marking, &failures);
2767 if (failures) {
2768 _failures = true;
2769 } else {
2770 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2771 r->object_iterate(¬_dead_yet_cl);
2772 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2773 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2774 "max_live_bytes "SIZE_FORMAT" "
2775 "< calculated "SIZE_FORMAT,
2776 r->bottom(), r->end(),
2777 r->max_live_bytes(),
2778 not_dead_yet_cl.live_bytes());
2779 _failures = true;
2780 }
2781 }
2782 }
2783 return false; // stop the region iteration if we hit a failure
2784 }
2785 };
2787 class VerifyRootsClosure: public OopsInGenClosure {
2788 private:
2789 G1CollectedHeap* _g1h;
2790 bool _use_prev_marking;
2791 bool _failures;
2792 public:
2793 // use_prev_marking == true -> use "prev" marking information,
2794 // use_prev_marking == false -> use "next" marking information
2795 VerifyRootsClosure(bool use_prev_marking) :
2796 _g1h(G1CollectedHeap::heap()),
2797 _use_prev_marking(use_prev_marking),
2798 _failures(false) { }
2800 bool failures() { return _failures; }
2802 template <class T> void do_oop_nv(T* p) {
2803 T heap_oop = oopDesc::load_heap_oop(p);
2804 if (!oopDesc::is_null(heap_oop)) {
2805 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2806 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2807 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2808 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2809 obj->print_on(gclog_or_tty);
2810 _failures = true;
2811 }
2812 }
2813 }
2815 void do_oop(oop* p) { do_oop_nv(p); }
2816 void do_oop(narrowOop* p) { do_oop_nv(p); }
2817 };
2819 // This is the task used for parallel heap verification.
2821 class G1ParVerifyTask: public AbstractGangTask {
2822 private:
2823 G1CollectedHeap* _g1h;
2824 bool _allow_dirty;
2825 bool _use_prev_marking;
2826 bool _failures;
2828 public:
2829 // use_prev_marking == true -> use "prev" marking information,
2830 // use_prev_marking == false -> use "next" marking information
2831 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2832 bool use_prev_marking) :
2833 AbstractGangTask("Parallel verify task"),
2834 _g1h(g1h),
2835 _allow_dirty(allow_dirty),
2836 _use_prev_marking(use_prev_marking),
2837 _failures(false) { }
2839 bool failures() {
2840 return _failures;
2841 }
2843 void work(int worker_i) {
2844 HandleMark hm;
2845 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2846 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2847 HeapRegion::ParVerifyClaimValue);
2848 if (blk.failures()) {
2849 _failures = true;
2850 }
2851 }
2852 };
2854 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2855 verify(allow_dirty, silent, /* use_prev_marking */ true);
2856 }
2858 void G1CollectedHeap::verify(bool allow_dirty,
2859 bool silent,
2860 bool use_prev_marking) {
2861 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2862 if (!silent) { gclog_or_tty->print("roots "); }
2863 VerifyRootsClosure rootsCl(use_prev_marking);
2864 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2865 process_strong_roots(true, // activate StrongRootsScope
2866 false,
2867 SharedHeap::SO_AllClasses,
2868 &rootsCl,
2869 &blobsCl,
2870 &rootsCl);
2871 bool failures = rootsCl.failures();
2872 rem_set()->invalidate(perm_gen()->used_region(), false);
2873 if (!silent) { gclog_or_tty->print("heapRegions "); }
2874 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2875 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2876 "sanity check");
2878 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2879 int n_workers = workers()->total_workers();
2880 set_par_threads(n_workers);
2881 workers()->run_task(&task);
2882 set_par_threads(0);
2883 if (task.failures()) {
2884 failures = true;
2885 }
2887 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2888 "sanity check");
2890 reset_heap_region_claim_values();
2892 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2893 "sanity check");
2894 } else {
2895 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2896 _hrs->iterate(&blk);
2897 if (blk.failures()) {
2898 failures = true;
2899 }
2900 }
2901 if (!silent) gclog_or_tty->print("remset ");
2902 rem_set()->verify();
2904 if (failures) {
2905 gclog_or_tty->print_cr("Heap:");
2906 print_on(gclog_or_tty, true /* extended */);
2907 gclog_or_tty->print_cr("");
2908 #ifndef PRODUCT
2909 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2910 concurrent_mark()->print_reachable("at-verification-failure",
2911 use_prev_marking, false /* all */);
2912 }
2913 #endif
2914 gclog_or_tty->flush();
2915 }
2916 guarantee(!failures, "there should not have been any failures");
2917 } else {
2918 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2919 }
2920 }
2922 class PrintRegionClosure: public HeapRegionClosure {
2923 outputStream* _st;
2924 public:
2925 PrintRegionClosure(outputStream* st) : _st(st) {}
2926 bool doHeapRegion(HeapRegion* r) {
2927 r->print_on(_st);
2928 return false;
2929 }
2930 };
2932 void G1CollectedHeap::print() const { print_on(tty); }
2934 void G1CollectedHeap::print_on(outputStream* st) const {
2935 print_on(st, PrintHeapAtGCExtended);
2936 }
2938 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2939 st->print(" %-20s", "garbage-first heap");
2940 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2941 capacity()/K, used_unlocked()/K);
2942 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2943 _g1_storage.low_boundary(),
2944 _g1_storage.high(),
2945 _g1_storage.high_boundary());
2946 st->cr();
2947 st->print(" region size " SIZE_FORMAT "K, ",
2948 HeapRegion::GrainBytes/K);
2949 size_t young_regions = _young_list->length();
2950 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2951 young_regions, young_regions * HeapRegion::GrainBytes / K);
2952 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2953 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2954 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2955 st->cr();
2956 perm()->as_gen()->print_on(st);
2957 if (extended) {
2958 st->cr();
2959 print_on_extended(st);
2960 }
2961 }
2963 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2964 PrintRegionClosure blk(st);
2965 _hrs->iterate(&blk);
2966 }
2968 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2969 if (G1CollectedHeap::use_parallel_gc_threads()) {
2970 workers()->print_worker_threads_on(st);
2971 }
2973 _cmThread->print_on(st);
2974 st->cr();
2976 _cm->print_worker_threads_on(st);
2978 _cg1r->print_worker_threads_on(st);
2980 _czft->print_on(st);
2981 st->cr();
2982 }
2984 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2985 if (G1CollectedHeap::use_parallel_gc_threads()) {
2986 workers()->threads_do(tc);
2987 }
2988 tc->do_thread(_cmThread);
2989 _cg1r->threads_do(tc);
2990 tc->do_thread(_czft);
2991 }
2993 void G1CollectedHeap::print_tracing_info() const {
2994 // We'll overload this to mean "trace GC pause statistics."
2995 if (TraceGen0Time || TraceGen1Time) {
2996 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2997 // to that.
2998 g1_policy()->print_tracing_info();
2999 }
3000 if (G1SummarizeRSetStats) {
3001 g1_rem_set()->print_summary_info();
3002 }
3003 if (G1SummarizeConcMark) {
3004 concurrent_mark()->print_summary_info();
3005 }
3006 if (G1SummarizeZFStats) {
3007 ConcurrentZFThread::print_summary_info();
3008 }
3009 g1_policy()->print_yg_surv_rate_info();
3011 SpecializationStats::print();
3012 }
3015 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
3016 HeapRegion* hr = heap_region_containing(addr);
3017 if (hr == NULL) {
3018 return 0;
3019 } else {
3020 return 1;
3021 }
3022 }
3024 G1CollectedHeap* G1CollectedHeap::heap() {
3025 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3026 "not a garbage-first heap");
3027 return _g1h;
3028 }
3030 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3031 // always_do_update_barrier = false;
3032 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3033 // Call allocation profiler
3034 AllocationProfiler::iterate_since_last_gc();
3035 // Fill TLAB's and such
3036 ensure_parsability(true);
3037 }
3039 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3040 // FIXME: what is this about?
3041 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3042 // is set.
3043 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3044 "derived pointer present"));
3045 // always_do_update_barrier = true;
3046 }
3048 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3049 unsigned int gc_count_before,
3050 bool* succeeded) {
3051 assert_heap_not_locked_and_not_at_safepoint();
3052 g1_policy()->record_stop_world_start();
3053 VM_G1IncCollectionPause op(gc_count_before,
3054 word_size,
3055 false, /* should_initiate_conc_mark */
3056 g1_policy()->max_pause_time_ms(),
3057 GCCause::_g1_inc_collection_pause);
3058 VMThread::execute(&op);
3060 HeapWord* result = op.result();
3061 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3062 assert(result == NULL || ret_succeeded,
3063 "the result should be NULL if the VM did not succeed");
3064 *succeeded = ret_succeeded;
3066 assert_heap_not_locked();
3067 return result;
3068 }
3070 void
3071 G1CollectedHeap::doConcurrentMark() {
3072 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3073 if (!_cmThread->in_progress()) {
3074 _cmThread->set_started();
3075 CGC_lock->notify();
3076 }
3077 }
3079 class VerifyMarkedObjsClosure: public ObjectClosure {
3080 G1CollectedHeap* _g1h;
3081 public:
3082 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
3083 void do_object(oop obj) {
3084 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
3085 "markandsweep mark should agree with concurrent deadness");
3086 }
3087 };
3089 void
3090 G1CollectedHeap::checkConcurrentMark() {
3091 VerifyMarkedObjsClosure verifycl(this);
3092 // MutexLockerEx x(getMarkBitMapLock(),
3093 // Mutex::_no_safepoint_check_flag);
3094 object_iterate(&verifycl, false);
3095 }
3097 void G1CollectedHeap::do_sync_mark() {
3098 _cm->checkpointRootsInitial();
3099 _cm->markFromRoots();
3100 _cm->checkpointRootsFinal(false);
3101 }
3103 // <NEW PREDICTION>
3105 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3106 bool young) {
3107 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3108 }
3110 void G1CollectedHeap::check_if_region_is_too_expensive(double
3111 predicted_time_ms) {
3112 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3113 }
3115 size_t G1CollectedHeap::pending_card_num() {
3116 size_t extra_cards = 0;
3117 JavaThread *curr = Threads::first();
3118 while (curr != NULL) {
3119 DirtyCardQueue& dcq = curr->dirty_card_queue();
3120 extra_cards += dcq.size();
3121 curr = curr->next();
3122 }
3123 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3124 size_t buffer_size = dcqs.buffer_size();
3125 size_t buffer_num = dcqs.completed_buffers_num();
3126 return buffer_size * buffer_num + extra_cards;
3127 }
3129 size_t G1CollectedHeap::max_pending_card_num() {
3130 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3131 size_t buffer_size = dcqs.buffer_size();
3132 size_t buffer_num = dcqs.completed_buffers_num();
3133 int thread_num = Threads::number_of_threads();
3134 return (buffer_num + thread_num) * buffer_size;
3135 }
3137 size_t G1CollectedHeap::cards_scanned() {
3138 return g1_rem_set()->cardsScanned();
3139 }
3141 void
3142 G1CollectedHeap::setup_surviving_young_words() {
3143 guarantee( _surviving_young_words == NULL, "pre-condition" );
3144 size_t array_length = g1_policy()->young_cset_length();
3145 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3146 if (_surviving_young_words == NULL) {
3147 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3148 "Not enough space for young surv words summary.");
3149 }
3150 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3151 #ifdef ASSERT
3152 for (size_t i = 0; i < array_length; ++i) {
3153 assert( _surviving_young_words[i] == 0, "memset above" );
3154 }
3155 #endif // !ASSERT
3156 }
3158 void
3159 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3160 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3161 size_t array_length = g1_policy()->young_cset_length();
3162 for (size_t i = 0; i < array_length; ++i)
3163 _surviving_young_words[i] += surv_young_words[i];
3164 }
3166 void
3167 G1CollectedHeap::cleanup_surviving_young_words() {
3168 guarantee( _surviving_young_words != NULL, "pre-condition" );
3169 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3170 _surviving_young_words = NULL;
3171 }
3173 // </NEW PREDICTION>
3175 struct PrepareForRSScanningClosure : public HeapRegionClosure {
3176 bool doHeapRegion(HeapRegion *r) {
3177 r->rem_set()->set_iter_claimed(0);
3178 return false;
3179 }
3180 };
3182 #if TASKQUEUE_STATS
3183 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3184 st->print_raw_cr("GC Task Stats");
3185 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3186 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3187 }
3189 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3190 print_taskqueue_stats_hdr(st);
3192 TaskQueueStats totals;
3193 const int n = workers() != NULL ? workers()->total_workers() : 1;
3194 for (int i = 0; i < n; ++i) {
3195 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3196 totals += task_queue(i)->stats;
3197 }
3198 st->print_raw("tot "); totals.print(st); st->cr();
3200 DEBUG_ONLY(totals.verify());
3201 }
3203 void G1CollectedHeap::reset_taskqueue_stats() {
3204 const int n = workers() != NULL ? workers()->total_workers() : 1;
3205 for (int i = 0; i < n; ++i) {
3206 task_queue(i)->stats.reset();
3207 }
3208 }
3209 #endif // TASKQUEUE_STATS
3211 bool
3212 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3213 if (GC_locker::check_active_before_gc()) {
3214 return false;
3215 }
3217 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3218 ResourceMark rm;
3220 if (PrintHeapAtGC) {
3221 Universe::print_heap_before_gc();
3222 }
3224 {
3225 // This call will decide whether this pause is an initial-mark
3226 // pause. If it is, during_initial_mark_pause() will return true
3227 // for the duration of this pause.
3228 g1_policy()->decide_on_conc_mark_initiation();
3230 char verbose_str[128];
3231 sprintf(verbose_str, "GC pause ");
3232 if (g1_policy()->in_young_gc_mode()) {
3233 if (g1_policy()->full_young_gcs())
3234 strcat(verbose_str, "(young)");
3235 else
3236 strcat(verbose_str, "(partial)");
3237 }
3238 if (g1_policy()->during_initial_mark_pause()) {
3239 strcat(verbose_str, " (initial-mark)");
3240 // We are about to start a marking cycle, so we increment the
3241 // full collection counter.
3242 increment_total_full_collections();
3243 }
3245 // if PrintGCDetails is on, we'll print long statistics information
3246 // in the collector policy code, so let's not print this as the output
3247 // is messy if we do.
3248 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3249 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3250 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3252 TraceMemoryManagerStats tms(false /* fullGC */);
3254 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
3255 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
3256 guarantee(!is_gc_active(), "collection is not reentrant");
3257 assert(regions_accounted_for(), "Region leakage!");
3259 increment_gc_time_stamp();
3261 if (g1_policy()->in_young_gc_mode()) {
3262 assert(check_young_list_well_formed(),
3263 "young list should be well formed");
3264 }
3266 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3267 IsGCActiveMark x;
3269 gc_prologue(false);
3270 increment_total_collections(false /* full gc */);
3272 #if G1_REM_SET_LOGGING
3273 gclog_or_tty->print_cr("\nJust chose CS, heap:");
3274 print();
3275 #endif
3277 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3278 HandleMark hm; // Discard invalid handles created during verification
3279 prepare_for_verify();
3280 gclog_or_tty->print(" VerifyBeforeGC:");
3281 Universe::verify(false);
3282 }
3284 COMPILER2_PRESENT(DerivedPointerTable::clear());
3286 // Please see comment in G1CollectedHeap::ref_processing_init()
3287 // to see how reference processing currently works in G1.
3288 //
3289 // We want to turn off ref discovery, if necessary, and turn it back on
3290 // on again later if we do. XXX Dubious: why is discovery disabled?
3291 bool was_enabled = ref_processor()->discovery_enabled();
3292 if (was_enabled) ref_processor()->disable_discovery();
3294 // Forget the current alloc region (we might even choose it to be part
3295 // of the collection set!).
3296 abandon_cur_alloc_region();
3298 // The elapsed time induced by the start time below deliberately elides
3299 // the possible verification above.
3300 double start_time_sec = os::elapsedTime();
3301 size_t start_used_bytes = used();
3303 #if YOUNG_LIST_VERBOSE
3304 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3305 _young_list->print();
3306 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3307 #endif // YOUNG_LIST_VERBOSE
3309 g1_policy()->record_collection_pause_start(start_time_sec,
3310 start_used_bytes);
3312 #if YOUNG_LIST_VERBOSE
3313 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3314 _young_list->print();
3315 #endif // YOUNG_LIST_VERBOSE
3317 if (g1_policy()->during_initial_mark_pause()) {
3318 concurrent_mark()->checkpointRootsInitialPre();
3319 }
3320 save_marks();
3322 // We must do this before any possible evacuation that should propagate
3323 // marks.
3324 if (mark_in_progress()) {
3325 double start_time_sec = os::elapsedTime();
3327 _cm->drainAllSATBBuffers();
3328 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3329 g1_policy()->record_satb_drain_time(finish_mark_ms);
3330 }
3331 // Record the number of elements currently on the mark stack, so we
3332 // only iterate over these. (Since evacuation may add to the mark
3333 // stack, doing more exposes race conditions.) If no mark is in
3334 // progress, this will be zero.
3335 _cm->set_oops_do_bound();
3337 assert(regions_accounted_for(), "Region leakage.");
3339 if (mark_in_progress())
3340 concurrent_mark()->newCSet();
3342 #if YOUNG_LIST_VERBOSE
3343 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3344 _young_list->print();
3345 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3346 #endif // YOUNG_LIST_VERBOSE
3348 g1_policy()->choose_collection_set(target_pause_time_ms);
3350 // Nothing to do if we were unable to choose a collection set.
3351 #if G1_REM_SET_LOGGING
3352 gclog_or_tty->print_cr("\nAfter pause, heap:");
3353 print();
3354 #endif
3355 PrepareForRSScanningClosure prepare_for_rs_scan;
3356 collection_set_iterate(&prepare_for_rs_scan);
3358 setup_surviving_young_words();
3360 // Set up the gc allocation regions.
3361 get_gc_alloc_regions();
3363 // Actually do the work...
3364 evacuate_collection_set();
3366 free_collection_set(g1_policy()->collection_set());
3367 g1_policy()->clear_collection_set();
3369 cleanup_surviving_young_words();
3371 // Start a new incremental collection set for the next pause.
3372 g1_policy()->start_incremental_cset_building();
3374 // Clear the _cset_fast_test bitmap in anticipation of adding
3375 // regions to the incremental collection set for the next
3376 // evacuation pause.
3377 clear_cset_fast_test();
3379 if (g1_policy()->in_young_gc_mode()) {
3380 _young_list->reset_sampled_info();
3382 // Don't check the whole heap at this point as the
3383 // GC alloc regions from this pause have been tagged
3384 // as survivors and moved on to the survivor list.
3385 // Survivor regions will fail the !is_young() check.
3386 assert(check_young_list_empty(false /* check_heap */),
3387 "young list should be empty");
3389 #if YOUNG_LIST_VERBOSE
3390 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3391 _young_list->print();
3392 #endif // YOUNG_LIST_VERBOSE
3394 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3395 _young_list->first_survivor_region(),
3396 _young_list->last_survivor_region());
3398 _young_list->reset_auxilary_lists();
3399 }
3401 if (evacuation_failed()) {
3402 _summary_bytes_used = recalculate_used();
3403 } else {
3404 // The "used" of the the collection set have already been subtracted
3405 // when they were freed. Add in the bytes evacuated.
3406 _summary_bytes_used += g1_policy()->bytes_in_to_space();
3407 }
3409 if (g1_policy()->in_young_gc_mode() &&
3410 g1_policy()->during_initial_mark_pause()) {
3411 concurrent_mark()->checkpointRootsInitialPost();
3412 set_marking_started();
3413 // CAUTION: after the doConcurrentMark() call below,
3414 // the concurrent marking thread(s) could be running
3415 // concurrently with us. Make sure that anything after
3416 // this point does not assume that we are the only GC thread
3417 // running. Note: of course, the actual marking work will
3418 // not start until the safepoint itself is released in
3419 // ConcurrentGCThread::safepoint_desynchronize().
3420 doConcurrentMark();
3421 }
3423 #if YOUNG_LIST_VERBOSE
3424 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3425 _young_list->print();
3426 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3427 #endif // YOUNG_LIST_VERBOSE
3429 double end_time_sec = os::elapsedTime();
3430 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3431 g1_policy()->record_pause_time_ms(pause_time_ms);
3432 g1_policy()->record_collection_pause_end();
3434 assert(regions_accounted_for(), "Region leakage.");
3436 MemoryService::track_memory_usage();
3438 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3439 HandleMark hm; // Discard invalid handles created during verification
3440 gclog_or_tty->print(" VerifyAfterGC:");
3441 prepare_for_verify();
3442 Universe::verify(false);
3443 }
3445 if (was_enabled) ref_processor()->enable_discovery();
3447 {
3448 size_t expand_bytes = g1_policy()->expansion_amount();
3449 if (expand_bytes > 0) {
3450 size_t bytes_before = capacity();
3451 expand(expand_bytes);
3452 }
3453 }
3455 if (mark_in_progress()) {
3456 concurrent_mark()->update_g1_committed();
3457 }
3459 #ifdef TRACESPINNING
3460 ParallelTaskTerminator::print_termination_counts();
3461 #endif
3463 gc_epilogue(false);
3464 }
3466 assert(verify_region_lists(), "Bad region lists.");
3468 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3469 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3470 print_tracing_info();
3471 vm_exit(-1);
3472 }
3473 }
3475 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3476 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3478 if (PrintHeapAtGC) {
3479 Universe::print_heap_after_gc();
3480 }
3481 if (G1SummarizeRSetStats &&
3482 (G1SummarizeRSetStatsPeriod > 0) &&
3483 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3484 g1_rem_set()->print_summary_info();
3485 }
3487 return true;
3488 }
3490 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3491 {
3492 size_t gclab_word_size;
3493 switch (purpose) {
3494 case GCAllocForSurvived:
3495 gclab_word_size = YoungPLABSize;
3496 break;
3497 case GCAllocForTenured:
3498 gclab_word_size = OldPLABSize;
3499 break;
3500 default:
3501 assert(false, "unknown GCAllocPurpose");
3502 gclab_word_size = OldPLABSize;
3503 break;
3504 }
3505 return gclab_word_size;
3506 }
3509 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
3510 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
3511 // make sure we don't call set_gc_alloc_region() multiple times on
3512 // the same region
3513 assert(r == NULL || !r->is_gc_alloc_region(),
3514 "shouldn't already be a GC alloc region");
3515 assert(r == NULL || !r->isHumongous(),
3516 "humongous regions shouldn't be used as GC alloc regions");
3518 HeapWord* original_top = NULL;
3519 if (r != NULL)
3520 original_top = r->top();
3522 // We will want to record the used space in r as being there before gc.
3523 // One we install it as a GC alloc region it's eligible for allocation.
3524 // So record it now and use it later.
3525 size_t r_used = 0;
3526 if (r != NULL) {
3527 r_used = r->used();
3529 if (G1CollectedHeap::use_parallel_gc_threads()) {
3530 // need to take the lock to guard against two threads calling
3531 // get_gc_alloc_region concurrently (very unlikely but...)
3532 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3533 r->save_marks();
3534 }
3535 }
3536 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
3537 _gc_alloc_regions[purpose] = r;
3538 if (old_alloc_region != NULL) {
3539 // Replace aliases too.
3540 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3541 if (_gc_alloc_regions[ap] == old_alloc_region) {
3542 _gc_alloc_regions[ap] = r;
3543 }
3544 }
3545 }
3546 if (r != NULL) {
3547 push_gc_alloc_region(r);
3548 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
3549 // We are using a region as a GC alloc region after it has been used
3550 // as a mutator allocation region during the current marking cycle.
3551 // The mutator-allocated objects are currently implicitly marked, but
3552 // when we move hr->next_top_at_mark_start() forward at the the end
3553 // of the GC pause, they won't be. We therefore mark all objects in
3554 // the "gap". We do this object-by-object, since marking densely
3555 // does not currently work right with marking bitmap iteration. This
3556 // means we rely on TLAB filling at the start of pauses, and no
3557 // "resuscitation" of filled TLAB's. If we want to do this, we need
3558 // to fix the marking bitmap iteration.
3559 HeapWord* curhw = r->next_top_at_mark_start();
3560 HeapWord* t = original_top;
3562 while (curhw < t) {
3563 oop cur = (oop)curhw;
3564 // We'll assume parallel for generality. This is rare code.
3565 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
3566 curhw = curhw + cur->size();
3567 }
3568 assert(curhw == t, "Should have parsed correctly.");
3569 }
3570 if (G1PolicyVerbose > 1) {
3571 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
3572 "for survivors:", r->bottom(), original_top, r->end());
3573 r->print();
3574 }
3575 g1_policy()->record_before_bytes(r_used);
3576 }
3577 }
3579 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
3580 assert(Thread::current()->is_VM_thread() ||
3581 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
3582 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
3583 "Precondition.");
3584 hr->set_is_gc_alloc_region(true);
3585 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
3586 _gc_alloc_region_list = hr;
3587 }
3589 #ifdef G1_DEBUG
3590 class FindGCAllocRegion: public HeapRegionClosure {
3591 public:
3592 bool doHeapRegion(HeapRegion* r) {
3593 if (r->is_gc_alloc_region()) {
3594 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
3595 r->hrs_index(), r->bottom());
3596 }
3597 return false;
3598 }
3599 };
3600 #endif // G1_DEBUG
3602 void G1CollectedHeap::forget_alloc_region_list() {
3603 assert(Thread::current()->is_VM_thread(), "Precondition");
3604 while (_gc_alloc_region_list != NULL) {
3605 HeapRegion* r = _gc_alloc_region_list;
3606 assert(r->is_gc_alloc_region(), "Invariant.");
3607 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
3608 // newly allocated data in order to be able to apply deferred updates
3609 // before the GC is done for verification purposes (i.e to allow
3610 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
3611 // collection.
3612 r->ContiguousSpace::set_saved_mark();
3613 _gc_alloc_region_list = r->next_gc_alloc_region();
3614 r->set_next_gc_alloc_region(NULL);
3615 r->set_is_gc_alloc_region(false);
3616 if (r->is_survivor()) {
3617 if (r->is_empty()) {
3618 r->set_not_young();
3619 } else {
3620 _young_list->add_survivor_region(r);
3621 }
3622 }
3623 if (r->is_empty()) {
3624 ++_free_regions;
3625 }
3626 }
3627 #ifdef G1_DEBUG
3628 FindGCAllocRegion fa;
3629 heap_region_iterate(&fa);
3630 #endif // G1_DEBUG
3631 }
3634 bool G1CollectedHeap::check_gc_alloc_regions() {
3635 // TODO: allocation regions check
3636 return true;
3637 }
3639 void G1CollectedHeap::get_gc_alloc_regions() {
3640 // First, let's check that the GC alloc region list is empty (it should)
3641 assert(_gc_alloc_region_list == NULL, "invariant");
3643 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3644 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3645 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3647 // Create new GC alloc regions.
3648 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3649 _retained_gc_alloc_regions[ap] = NULL;
3651 if (alloc_region != NULL) {
3652 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3654 // let's make sure that the GC alloc region is not tagged as such
3655 // outside a GC operation
3656 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3658 if (alloc_region->in_collection_set() ||
3659 alloc_region->top() == alloc_region->end() ||
3660 alloc_region->top() == alloc_region->bottom() ||
3661 alloc_region->isHumongous()) {
3662 // we will discard the current GC alloc region if
3663 // * it's in the collection set (it can happen!),
3664 // * it's already full (no point in using it),
3665 // * it's empty (this means that it was emptied during
3666 // a cleanup and it should be on the free list now), or
3667 // * it's humongous (this means that it was emptied
3668 // during a cleanup and was added to the free list, but
3669 // has been subseqently used to allocate a humongous
3670 // object that may be less than the region size).
3672 alloc_region = NULL;
3673 }
3674 }
3676 if (alloc_region == NULL) {
3677 // we will get a new GC alloc region
3678 alloc_region = newAllocRegionWithExpansion(ap, 0);
3679 } else {
3680 // the region was retained from the last collection
3681 ++_gc_alloc_region_counts[ap];
3682 if (G1PrintHeapRegions) {
3683 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
3684 "top "PTR_FORMAT,
3685 alloc_region->hrs_index(), alloc_region->bottom(), alloc_region->end(), alloc_region->top());
3686 }
3687 }
3689 if (alloc_region != NULL) {
3690 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3691 set_gc_alloc_region(ap, alloc_region);
3692 }
3694 assert(_gc_alloc_regions[ap] == NULL ||
3695 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3696 "the GC alloc region should be tagged as such");
3697 assert(_gc_alloc_regions[ap] == NULL ||
3698 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3699 "the GC alloc region should be the same as the GC alloc list head");
3700 }
3701 // Set alternative regions for allocation purposes that have reached
3702 // their limit.
3703 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3704 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3705 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3706 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3707 }
3708 }
3709 assert(check_gc_alloc_regions(), "alloc regions messed up");
3710 }
3712 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3713 // We keep a separate list of all regions that have been alloc regions in
3714 // the current collection pause. Forget that now. This method will
3715 // untag the GC alloc regions and tear down the GC alloc region
3716 // list. It's desirable that no regions are tagged as GC alloc
3717 // outside GCs.
3719 forget_alloc_region_list();
3721 // The current alloc regions contain objs that have survived
3722 // collection. Make them no longer GC alloc regions.
3723 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3724 HeapRegion* r = _gc_alloc_regions[ap];
3725 _retained_gc_alloc_regions[ap] = NULL;
3726 _gc_alloc_region_counts[ap] = 0;
3728 if (r != NULL) {
3729 // we retain nothing on _gc_alloc_regions between GCs
3730 set_gc_alloc_region(ap, NULL);
3732 if (r->is_empty()) {
3733 // we didn't actually allocate anything in it; let's just put
3734 // it on the free list
3735 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
3736 r->set_zero_fill_complete();
3737 put_free_region_on_list_locked(r);
3738 } else if (_retain_gc_alloc_region[ap] && !totally) {
3739 // retain it so that we can use it at the beginning of the next GC
3740 _retained_gc_alloc_regions[ap] = r;
3741 }
3742 }
3743 }
3744 }
3746 #ifndef PRODUCT
3747 // Useful for debugging
3749 void G1CollectedHeap::print_gc_alloc_regions() {
3750 gclog_or_tty->print_cr("GC alloc regions");
3751 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3752 HeapRegion* r = _gc_alloc_regions[ap];
3753 if (r == NULL) {
3754 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3755 } else {
3756 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3757 ap, r->bottom(), r->used());
3758 }
3759 }
3760 }
3761 #endif // PRODUCT
3763 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3764 _drain_in_progress = false;
3765 set_evac_failure_closure(cl);
3766 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3767 }
3769 void G1CollectedHeap::finalize_for_evac_failure() {
3770 assert(_evac_failure_scan_stack != NULL &&
3771 _evac_failure_scan_stack->length() == 0,
3772 "Postcondition");
3773 assert(!_drain_in_progress, "Postcondition");
3774 delete _evac_failure_scan_stack;
3775 _evac_failure_scan_stack = NULL;
3776 }
3780 // *** Sequential G1 Evacuation
3782 class G1IsAliveClosure: public BoolObjectClosure {
3783 G1CollectedHeap* _g1;
3784 public:
3785 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3786 void do_object(oop p) { assert(false, "Do not call."); }
3787 bool do_object_b(oop p) {
3788 // It is reachable if it is outside the collection set, or is inside
3789 // and forwarded.
3791 #ifdef G1_DEBUG
3792 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3793 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3794 !_g1->obj_in_cs(p) || p->is_forwarded());
3795 #endif // G1_DEBUG
3797 return !_g1->obj_in_cs(p) || p->is_forwarded();
3798 }
3799 };
3801 class G1KeepAliveClosure: public OopClosure {
3802 G1CollectedHeap* _g1;
3803 public:
3804 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3805 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3806 void do_oop( oop* p) {
3807 oop obj = *p;
3808 #ifdef G1_DEBUG
3809 if (PrintGC && Verbose) {
3810 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3811 p, (void*) obj, (void*) *p);
3812 }
3813 #endif // G1_DEBUG
3815 if (_g1->obj_in_cs(obj)) {
3816 assert( obj->is_forwarded(), "invariant" );
3817 *p = obj->forwardee();
3818 #ifdef G1_DEBUG
3819 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3820 (void*) obj, (void*) *p);
3821 #endif // G1_DEBUG
3822 }
3823 }
3824 };
3826 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3827 private:
3828 G1CollectedHeap* _g1;
3829 DirtyCardQueue *_dcq;
3830 CardTableModRefBS* _ct_bs;
3832 public:
3833 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3834 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3836 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3837 virtual void do_oop( oop* p) { do_oop_work(p); }
3838 template <class T> void do_oop_work(T* p) {
3839 assert(_from->is_in_reserved(p), "paranoia");
3840 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3841 !_from->is_survivor()) {
3842 size_t card_index = _ct_bs->index_for(p);
3843 if (_ct_bs->mark_card_deferred(card_index)) {
3844 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3845 }
3846 }
3847 }
3848 };
3850 class RemoveSelfPointerClosure: public ObjectClosure {
3851 private:
3852 G1CollectedHeap* _g1;
3853 ConcurrentMark* _cm;
3854 HeapRegion* _hr;
3855 size_t _prev_marked_bytes;
3856 size_t _next_marked_bytes;
3857 OopsInHeapRegionClosure *_cl;
3858 public:
3859 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3860 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3861 _next_marked_bytes(0), _cl(cl) {}
3863 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3864 size_t next_marked_bytes() { return _next_marked_bytes; }
3866 // The original idea here was to coalesce evacuated and dead objects.
3867 // However that caused complications with the block offset table (BOT).
3868 // In particular if there were two TLABs, one of them partially refined.
3869 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3870 // The BOT entries of the unrefined part of TLAB_2 point to the start
3871 // of TLAB_2. If the last object of the TLAB_1 and the first object
3872 // of TLAB_2 are coalesced, then the cards of the unrefined part
3873 // would point into middle of the filler object.
3874 //
3875 // The current approach is to not coalesce and leave the BOT contents intact.
3876 void do_object(oop obj) {
3877 if (obj->is_forwarded() && obj->forwardee() == obj) {
3878 // The object failed to move.
3879 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3880 _cm->markPrev(obj);
3881 assert(_cm->isPrevMarked(obj), "Should be marked!");
3882 _prev_marked_bytes += (obj->size() * HeapWordSize);
3883 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3884 _cm->markAndGrayObjectIfNecessary(obj);
3885 }
3886 obj->set_mark(markOopDesc::prototype());
3887 // While we were processing RSet buffers during the
3888 // collection, we actually didn't scan any cards on the
3889 // collection set, since we didn't want to update remebered
3890 // sets with entries that point into the collection set, given
3891 // that live objects fromthe collection set are about to move
3892 // and such entries will be stale very soon. This change also
3893 // dealt with a reliability issue which involved scanning a
3894 // card in the collection set and coming across an array that
3895 // was being chunked and looking malformed. The problem is
3896 // that, if evacuation fails, we might have remembered set
3897 // entries missing given that we skipped cards on the
3898 // collection set. So, we'll recreate such entries now.
3899 obj->oop_iterate(_cl);
3900 assert(_cm->isPrevMarked(obj), "Should be marked!");
3901 } else {
3902 // The object has been either evacuated or is dead. Fill it with a
3903 // dummy object.
3904 MemRegion mr((HeapWord*)obj, obj->size());
3905 CollectedHeap::fill_with_object(mr);
3906 _cm->clearRangeBothMaps(mr);
3907 }
3908 }
3909 };
3911 void G1CollectedHeap::remove_self_forwarding_pointers() {
3912 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
3913 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3914 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3915 OopsInHeapRegionClosure *cl;
3916 if (G1DeferredRSUpdate) {
3917 cl = &deferred_update;
3918 } else {
3919 cl = &immediate_update;
3920 }
3921 HeapRegion* cur = g1_policy()->collection_set();
3922 while (cur != NULL) {
3923 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3925 RemoveSelfPointerClosure rspc(_g1h, cl);
3926 if (cur->evacuation_failed()) {
3927 assert(cur->in_collection_set(), "bad CS");
3928 cl->set_region(cur);
3929 cur->object_iterate(&rspc);
3931 // A number of manipulations to make the TAMS be the current top,
3932 // and the marked bytes be the ones observed in the iteration.
3933 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3934 // The comments below are the postconditions achieved by the
3935 // calls. Note especially the last such condition, which says that
3936 // the count of marked bytes has been properly restored.
3937 cur->note_start_of_marking(false);
3938 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3939 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3940 // _next_marked_bytes == prev_marked_bytes.
3941 cur->note_end_of_marking();
3942 // _prev_top_at_mark_start == top(),
3943 // _prev_marked_bytes == prev_marked_bytes
3944 }
3945 // If there is no mark in progress, we modified the _next variables
3946 // above needlessly, but harmlessly.
3947 if (_g1h->mark_in_progress()) {
3948 cur->note_start_of_marking(false);
3949 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3950 // _next_marked_bytes == next_marked_bytes.
3951 }
3953 // Now make sure the region has the right index in the sorted array.
3954 g1_policy()->note_change_in_marked_bytes(cur);
3955 }
3956 cur = cur->next_in_collection_set();
3957 }
3958 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3960 // Now restore saved marks, if any.
3961 if (_objs_with_preserved_marks != NULL) {
3962 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3963 guarantee(_objs_with_preserved_marks->length() ==
3964 _preserved_marks_of_objs->length(), "Both or none.");
3965 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3966 oop obj = _objs_with_preserved_marks->at(i);
3967 markOop m = _preserved_marks_of_objs->at(i);
3968 obj->set_mark(m);
3969 }
3970 // Delete the preserved marks growable arrays (allocated on the C heap).
3971 delete _objs_with_preserved_marks;
3972 delete _preserved_marks_of_objs;
3973 _objs_with_preserved_marks = NULL;
3974 _preserved_marks_of_objs = NULL;
3975 }
3976 }
3978 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3979 _evac_failure_scan_stack->push(obj);
3980 }
3982 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3983 assert(_evac_failure_scan_stack != NULL, "precondition");
3985 while (_evac_failure_scan_stack->length() > 0) {
3986 oop obj = _evac_failure_scan_stack->pop();
3987 _evac_failure_closure->set_region(heap_region_containing(obj));
3988 obj->oop_iterate_backwards(_evac_failure_closure);
3989 }
3990 }
3992 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3993 markOop m = old->mark();
3994 // forward to self
3995 assert(!old->is_forwarded(), "precondition");
3997 old->forward_to(old);
3998 handle_evacuation_failure_common(old, m);
3999 }
4001 oop
4002 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4003 oop old) {
4004 markOop m = old->mark();
4005 oop forward_ptr = old->forward_to_atomic(old);
4006 if (forward_ptr == NULL) {
4007 // Forward-to-self succeeded.
4008 if (_evac_failure_closure != cl) {
4009 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4010 assert(!_drain_in_progress,
4011 "Should only be true while someone holds the lock.");
4012 // Set the global evac-failure closure to the current thread's.
4013 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4014 set_evac_failure_closure(cl);
4015 // Now do the common part.
4016 handle_evacuation_failure_common(old, m);
4017 // Reset to NULL.
4018 set_evac_failure_closure(NULL);
4019 } else {
4020 // The lock is already held, and this is recursive.
4021 assert(_drain_in_progress, "This should only be the recursive case.");
4022 handle_evacuation_failure_common(old, m);
4023 }
4024 return old;
4025 } else {
4026 // Someone else had a place to copy it.
4027 return forward_ptr;
4028 }
4029 }
4031 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4032 set_evacuation_failed(true);
4034 preserve_mark_if_necessary(old, m);
4036 HeapRegion* r = heap_region_containing(old);
4037 if (!r->evacuation_failed()) {
4038 r->set_evacuation_failed(true);
4039 if (G1PrintHeapRegions) {
4040 gclog_or_tty->print("overflow in heap region "PTR_FORMAT" "
4041 "["PTR_FORMAT","PTR_FORMAT")\n",
4042 r, r->bottom(), r->end());
4043 }
4044 }
4046 push_on_evac_failure_scan_stack(old);
4048 if (!_drain_in_progress) {
4049 // prevent recursion in copy_to_survivor_space()
4050 _drain_in_progress = true;
4051 drain_evac_failure_scan_stack();
4052 _drain_in_progress = false;
4053 }
4054 }
4056 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4057 assert(evacuation_failed(), "Oversaving!");
4058 // We want to call the "for_promotion_failure" version only in the
4059 // case of a promotion failure.
4060 if (m->must_be_preserved_for_promotion_failure(obj)) {
4061 if (_objs_with_preserved_marks == NULL) {
4062 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4063 _objs_with_preserved_marks =
4064 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4065 _preserved_marks_of_objs =
4066 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4067 }
4068 _objs_with_preserved_marks->push(obj);
4069 _preserved_marks_of_objs->push(m);
4070 }
4071 }
4073 // *** Parallel G1 Evacuation
4075 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4076 size_t word_size) {
4077 assert(!isHumongous(word_size),
4078 err_msg("we should not be seeing humongous allocation requests "
4079 "during GC, word_size = "SIZE_FORMAT, word_size));
4081 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
4082 // let the caller handle alloc failure
4083 if (alloc_region == NULL) return NULL;
4085 HeapWord* block = alloc_region->par_allocate(word_size);
4086 if (block == NULL) {
4087 MutexLockerEx x(par_alloc_during_gc_lock(),
4088 Mutex::_no_safepoint_check_flag);
4089 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
4090 }
4091 return block;
4092 }
4094 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
4095 bool par) {
4096 // Another thread might have obtained alloc_region for the given
4097 // purpose, and might be attempting to allocate in it, and might
4098 // succeed. Therefore, we can't do the "finalization" stuff on the
4099 // region below until we're sure the last allocation has happened.
4100 // We ensure this by allocating the remaining space with a garbage
4101 // object.
4102 if (par) par_allocate_remaining_space(alloc_region);
4103 // Now we can do the post-GC stuff on the region.
4104 alloc_region->note_end_of_copying();
4105 g1_policy()->record_after_bytes(alloc_region->used());
4106 }
4108 HeapWord*
4109 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
4110 HeapRegion* alloc_region,
4111 bool par,
4112 size_t word_size) {
4113 assert(!isHumongous(word_size),
4114 err_msg("we should not be seeing humongous allocation requests "
4115 "during GC, word_size = "SIZE_FORMAT, word_size));
4117 HeapWord* block = NULL;
4118 // In the parallel case, a previous thread to obtain the lock may have
4119 // already assigned a new gc_alloc_region.
4120 if (alloc_region != _gc_alloc_regions[purpose]) {
4121 assert(par, "But should only happen in parallel case.");
4122 alloc_region = _gc_alloc_regions[purpose];
4123 if (alloc_region == NULL) return NULL;
4124 block = alloc_region->par_allocate(word_size);
4125 if (block != NULL) return block;
4126 // Otherwise, continue; this new region is empty, too.
4127 }
4128 assert(alloc_region != NULL, "We better have an allocation region");
4129 retire_alloc_region(alloc_region, par);
4131 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
4132 // Cannot allocate more regions for the given purpose.
4133 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
4134 // Is there an alternative?
4135 if (purpose != alt_purpose) {
4136 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
4137 // Has not the alternative region been aliased?
4138 if (alloc_region != alt_region && alt_region != NULL) {
4139 // Try to allocate in the alternative region.
4140 if (par) {
4141 block = alt_region->par_allocate(word_size);
4142 } else {
4143 block = alt_region->allocate(word_size);
4144 }
4145 // Make an alias.
4146 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
4147 if (block != NULL) {
4148 return block;
4149 }
4150 retire_alloc_region(alt_region, par);
4151 }
4152 // Both the allocation region and the alternative one are full
4153 // and aliased, replace them with a new allocation region.
4154 purpose = alt_purpose;
4155 } else {
4156 set_gc_alloc_region(purpose, NULL);
4157 return NULL;
4158 }
4159 }
4161 // Now allocate a new region for allocation.
4162 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
4164 // let the caller handle alloc failure
4165 if (alloc_region != NULL) {
4167 assert(check_gc_alloc_regions(), "alloc regions messed up");
4168 assert(alloc_region->saved_mark_at_top(),
4169 "Mark should have been saved already.");
4170 // We used to assert that the region was zero-filled here, but no
4171 // longer.
4173 // This must be done last: once it's installed, other regions may
4174 // allocate in it (without holding the lock.)
4175 set_gc_alloc_region(purpose, alloc_region);
4177 if (par) {
4178 block = alloc_region->par_allocate(word_size);
4179 } else {
4180 block = alloc_region->allocate(word_size);
4181 }
4182 // Caller handles alloc failure.
4183 } else {
4184 // This sets other apis using the same old alloc region to NULL, also.
4185 set_gc_alloc_region(purpose, NULL);
4186 }
4187 return block; // May be NULL.
4188 }
4190 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
4191 HeapWord* block = NULL;
4192 size_t free_words;
4193 do {
4194 free_words = r->free()/HeapWordSize;
4195 // If there's too little space, no one can allocate, so we're done.
4196 if (free_words < CollectedHeap::min_fill_size()) return;
4197 // Otherwise, try to claim it.
4198 block = r->par_allocate(free_words);
4199 } while (block == NULL);
4200 fill_with_object(block, free_words);
4201 }
4203 #ifndef PRODUCT
4204 bool GCLabBitMapClosure::do_bit(size_t offset) {
4205 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4206 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4207 return true;
4208 }
4209 #endif // PRODUCT
4211 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4212 : _g1h(g1h),
4213 _refs(g1h->task_queue(queue_num)),
4214 _dcq(&g1h->dirty_card_queue_set()),
4215 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4216 _g1_rem(g1h->g1_rem_set()),
4217 _hash_seed(17), _queue_num(queue_num),
4218 _term_attempts(0),
4219 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4220 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4221 _age_table(false),
4222 _strong_roots_time(0), _term_time(0),
4223 _alloc_buffer_waste(0), _undo_waste(0)
4224 {
4225 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4226 // we "sacrifice" entry 0 to keep track of surviving bytes for
4227 // non-young regions (where the age is -1)
4228 // We also add a few elements at the beginning and at the end in
4229 // an attempt to eliminate cache contention
4230 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
4231 size_t array_length = PADDING_ELEM_NUM +
4232 real_length +
4233 PADDING_ELEM_NUM;
4234 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4235 if (_surviving_young_words_base == NULL)
4236 vm_exit_out_of_memory(array_length * sizeof(size_t),
4237 "Not enough space for young surv histo.");
4238 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4239 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4241 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4242 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4244 _start = os::elapsedTime();
4245 }
4247 void
4248 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4249 {
4250 st->print_raw_cr("GC Termination Stats");
4251 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4252 " ------waste (KiB)------");
4253 st->print_raw_cr("thr ms ms % ms % attempts"
4254 " total alloc undo");
4255 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4256 " ------- ------- -------");
4257 }
4259 void
4260 G1ParScanThreadState::print_termination_stats(int i,
4261 outputStream* const st) const
4262 {
4263 const double elapsed_ms = elapsed_time() * 1000.0;
4264 const double s_roots_ms = strong_roots_time() * 1000.0;
4265 const double term_ms = term_time() * 1000.0;
4266 st->print_cr("%3d %9.2f %9.2f %6.2f "
4267 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4268 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4269 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4270 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4271 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4272 alloc_buffer_waste() * HeapWordSize / K,
4273 undo_waste() * HeapWordSize / K);
4274 }
4276 #ifdef ASSERT
4277 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4278 assert(ref != NULL, "invariant");
4279 assert(UseCompressedOops, "sanity");
4280 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4281 oop p = oopDesc::load_decode_heap_oop(ref);
4282 assert(_g1h->is_in_g1_reserved(p),
4283 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4284 return true;
4285 }
4287 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4288 assert(ref != NULL, "invariant");
4289 if (has_partial_array_mask(ref)) {
4290 // Must be in the collection set--it's already been copied.
4291 oop p = clear_partial_array_mask(ref);
4292 assert(_g1h->obj_in_cs(p),
4293 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4294 } else {
4295 oop p = oopDesc::load_decode_heap_oop(ref);
4296 assert(_g1h->is_in_g1_reserved(p),
4297 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4298 }
4299 return true;
4300 }
4302 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4303 if (ref.is_narrow()) {
4304 return verify_ref((narrowOop*) ref);
4305 } else {
4306 return verify_ref((oop*) ref);
4307 }
4308 }
4309 #endif // ASSERT
4311 void G1ParScanThreadState::trim_queue() {
4312 StarTask ref;
4313 do {
4314 // Drain the overflow stack first, so other threads can steal.
4315 while (refs()->pop_overflow(ref)) {
4316 deal_with_reference(ref);
4317 }
4318 while (refs()->pop_local(ref)) {
4319 deal_with_reference(ref);
4320 }
4321 } while (!refs()->is_empty());
4322 }
4324 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4325 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4326 _par_scan_state(par_scan_state) { }
4328 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
4329 // This is called _after_ do_oop_work has been called, hence after
4330 // the object has been relocated to its new location and *p points
4331 // to its new location.
4333 T heap_oop = oopDesc::load_heap_oop(p);
4334 if (!oopDesc::is_null(heap_oop)) {
4335 oop obj = oopDesc::decode_heap_oop(heap_oop);
4336 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
4337 "shouldn't still be in the CSet if evacuation didn't fail.");
4338 HeapWord* addr = (HeapWord*)obj;
4339 if (_g1->is_in_g1_reserved(addr))
4340 _cm->grayRoot(oop(addr));
4341 }
4342 }
4344 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4345 size_t word_sz = old->size();
4346 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4347 // +1 to make the -1 indexes valid...
4348 int young_index = from_region->young_index_in_cset()+1;
4349 assert( (from_region->is_young() && young_index > 0) ||
4350 (!from_region->is_young() && young_index == 0), "invariant" );
4351 G1CollectorPolicy* g1p = _g1->g1_policy();
4352 markOop m = old->mark();
4353 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4354 : m->age();
4355 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4356 word_sz);
4357 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4358 oop obj = oop(obj_ptr);
4360 if (obj_ptr == NULL) {
4361 // This will either forward-to-self, or detect that someone else has
4362 // installed a forwarding pointer.
4363 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4364 return _g1->handle_evacuation_failure_par(cl, old);
4365 }
4367 // We're going to allocate linearly, so might as well prefetch ahead.
4368 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4370 oop forward_ptr = old->forward_to_atomic(obj);
4371 if (forward_ptr == NULL) {
4372 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4373 if (g1p->track_object_age(alloc_purpose)) {
4374 // We could simply do obj->incr_age(). However, this causes a
4375 // performance issue. obj->incr_age() will first check whether
4376 // the object has a displaced mark by checking its mark word;
4377 // getting the mark word from the new location of the object
4378 // stalls. So, given that we already have the mark word and we
4379 // are about to install it anyway, it's better to increase the
4380 // age on the mark word, when the object does not have a
4381 // displaced mark word. We're not expecting many objects to have
4382 // a displaced marked word, so that case is not optimized
4383 // further (it could be...) and we simply call obj->incr_age().
4385 if (m->has_displaced_mark_helper()) {
4386 // in this case, we have to install the mark word first,
4387 // otherwise obj looks to be forwarded (the old mark word,
4388 // which contains the forward pointer, was copied)
4389 obj->set_mark(m);
4390 obj->incr_age();
4391 } else {
4392 m = m->incr_age();
4393 obj->set_mark(m);
4394 }
4395 _par_scan_state->age_table()->add(obj, word_sz);
4396 } else {
4397 obj->set_mark(m);
4398 }
4400 // preserve "next" mark bit
4401 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4402 if (!use_local_bitmaps ||
4403 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4404 // if we couldn't mark it on the local bitmap (this happens when
4405 // the object was not allocated in the GCLab), we have to bite
4406 // the bullet and do the standard parallel mark
4407 _cm->markAndGrayObjectIfNecessary(obj);
4408 }
4409 #if 1
4410 if (_g1->isMarkedNext(old)) {
4411 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4412 }
4413 #endif
4414 }
4416 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4417 surv_young_words[young_index] += word_sz;
4419 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4420 arrayOop(old)->set_length(0);
4421 oop* old_p = set_partial_array_mask(old);
4422 _par_scan_state->push_on_queue(old_p);
4423 } else {
4424 // No point in using the slower heap_region_containing() method,
4425 // given that we know obj is in the heap.
4426 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4427 obj->oop_iterate_backwards(_scanner);
4428 }
4429 } else {
4430 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4431 obj = forward_ptr;
4432 }
4433 return obj;
4434 }
4436 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
4437 template <class T>
4438 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
4439 ::do_oop_work(T* p) {
4440 oop obj = oopDesc::load_decode_heap_oop(p);
4441 assert(barrier != G1BarrierRS || obj != NULL,
4442 "Precondition: G1BarrierRS implies obj is nonNull");
4444 // here the null check is implicit in the cset_fast_test() test
4445 if (_g1->in_cset_fast_test(obj)) {
4446 #if G1_REM_SET_LOGGING
4447 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4448 "into CS.", p, (void*) obj);
4449 #endif
4450 if (obj->is_forwarded()) {
4451 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4452 } else {
4453 oop copy_oop = copy_to_survivor_space(obj);
4454 oopDesc::encode_store_heap_oop(p, copy_oop);
4455 }
4456 // When scanning the RS, we only care about objs in CS.
4457 if (barrier == G1BarrierRS) {
4458 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4459 }
4460 }
4462 if (barrier == G1BarrierEvac && obj != NULL) {
4463 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4464 }
4466 if (do_gen_barrier && obj != NULL) {
4467 par_do_barrier(p);
4468 }
4469 }
4471 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4472 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4474 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4475 assert(has_partial_array_mask(p), "invariant");
4476 oop old = clear_partial_array_mask(p);
4477 assert(old->is_objArray(), "must be obj array");
4478 assert(old->is_forwarded(), "must be forwarded");
4479 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4481 objArrayOop obj = objArrayOop(old->forwardee());
4482 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4483 // Process ParGCArrayScanChunk elements now
4484 // and push the remainder back onto queue
4485 int start = arrayOop(old)->length();
4486 int end = obj->length();
4487 int remainder = end - start;
4488 assert(start <= end, "just checking");
4489 if (remainder > 2 * ParGCArrayScanChunk) {
4490 // Test above combines last partial chunk with a full chunk
4491 end = start + ParGCArrayScanChunk;
4492 arrayOop(old)->set_length(end);
4493 // Push remainder.
4494 oop* old_p = set_partial_array_mask(old);
4495 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4496 _par_scan_state->push_on_queue(old_p);
4497 } else {
4498 // Restore length so that the heap remains parsable in
4499 // case of evacuation failure.
4500 arrayOop(old)->set_length(end);
4501 }
4502 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4503 // process our set of indices (include header in first chunk)
4504 obj->oop_iterate_range(&_scanner, start, end);
4505 }
4507 class G1ParEvacuateFollowersClosure : public VoidClosure {
4508 protected:
4509 G1CollectedHeap* _g1h;
4510 G1ParScanThreadState* _par_scan_state;
4511 RefToScanQueueSet* _queues;
4512 ParallelTaskTerminator* _terminator;
4514 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4515 RefToScanQueueSet* queues() { return _queues; }
4516 ParallelTaskTerminator* terminator() { return _terminator; }
4518 public:
4519 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4520 G1ParScanThreadState* par_scan_state,
4521 RefToScanQueueSet* queues,
4522 ParallelTaskTerminator* terminator)
4523 : _g1h(g1h), _par_scan_state(par_scan_state),
4524 _queues(queues), _terminator(terminator) {}
4526 void do_void();
4528 private:
4529 inline bool offer_termination();
4530 };
4532 bool G1ParEvacuateFollowersClosure::offer_termination() {
4533 G1ParScanThreadState* const pss = par_scan_state();
4534 pss->start_term_time();
4535 const bool res = terminator()->offer_termination();
4536 pss->end_term_time();
4537 return res;
4538 }
4540 void G1ParEvacuateFollowersClosure::do_void() {
4541 StarTask stolen_task;
4542 G1ParScanThreadState* const pss = par_scan_state();
4543 pss->trim_queue();
4545 do {
4546 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4547 assert(pss->verify_task(stolen_task), "sanity");
4548 if (stolen_task.is_narrow()) {
4549 pss->deal_with_reference((narrowOop*) stolen_task);
4550 } else {
4551 pss->deal_with_reference((oop*) stolen_task);
4552 }
4554 // We've just processed a reference and we might have made
4555 // available new entries on the queues. So we have to make sure
4556 // we drain the queues as necessary.
4557 pss->trim_queue();
4558 }
4559 } while (!offer_termination());
4561 pss->retire_alloc_buffers();
4562 }
4564 class G1ParTask : public AbstractGangTask {
4565 protected:
4566 G1CollectedHeap* _g1h;
4567 RefToScanQueueSet *_queues;
4568 ParallelTaskTerminator _terminator;
4569 int _n_workers;
4571 Mutex _stats_lock;
4572 Mutex* stats_lock() { return &_stats_lock; }
4574 size_t getNCards() {
4575 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4576 / G1BlockOffsetSharedArray::N_bytes;
4577 }
4579 public:
4580 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4581 : AbstractGangTask("G1 collection"),
4582 _g1h(g1h),
4583 _queues(task_queues),
4584 _terminator(workers, _queues),
4585 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4586 _n_workers(workers)
4587 {}
4589 RefToScanQueueSet* queues() { return _queues; }
4591 RefToScanQueue *work_queue(int i) {
4592 return queues()->queue(i);
4593 }
4595 void work(int i) {
4596 if (i >= _n_workers) return; // no work needed this round
4598 double start_time_ms = os::elapsedTime() * 1000.0;
4599 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4601 ResourceMark rm;
4602 HandleMark hm;
4604 G1ParScanThreadState pss(_g1h, i);
4605 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4606 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4607 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4609 pss.set_evac_closure(&scan_evac_cl);
4610 pss.set_evac_failure_closure(&evac_failure_cl);
4611 pss.set_partial_scan_closure(&partial_scan_cl);
4613 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4614 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4615 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4616 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4618 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4619 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4620 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4622 OopsInHeapRegionClosure *scan_root_cl;
4623 OopsInHeapRegionClosure *scan_perm_cl;
4625 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4626 scan_root_cl = &scan_mark_root_cl;
4627 scan_perm_cl = &scan_mark_perm_cl;
4628 } else {
4629 scan_root_cl = &only_scan_root_cl;
4630 scan_perm_cl = &only_scan_perm_cl;
4631 }
4633 pss.start_strong_roots();
4634 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4635 SharedHeap::SO_AllClasses,
4636 scan_root_cl,
4637 &push_heap_rs_cl,
4638 scan_perm_cl,
4639 i);
4640 pss.end_strong_roots();
4641 {
4642 double start = os::elapsedTime();
4643 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4644 evac.do_void();
4645 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4646 double term_ms = pss.term_time()*1000.0;
4647 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4648 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4649 }
4650 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4651 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4653 // Clean up any par-expanded rem sets.
4654 HeapRegionRemSet::par_cleanup();
4656 if (ParallelGCVerbose) {
4657 MutexLocker x(stats_lock());
4658 pss.print_termination_stats(i);
4659 }
4661 assert(pss.refs()->is_empty(), "should be empty");
4662 double end_time_ms = os::elapsedTime() * 1000.0;
4663 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4664 }
4665 };
4667 // *** Common G1 Evacuation Stuff
4669 // This method is run in a GC worker.
4671 void
4672 G1CollectedHeap::
4673 g1_process_strong_roots(bool collecting_perm_gen,
4674 SharedHeap::ScanningOption so,
4675 OopClosure* scan_non_heap_roots,
4676 OopsInHeapRegionClosure* scan_rs,
4677 OopsInGenClosure* scan_perm,
4678 int worker_i) {
4679 // First scan the strong roots, including the perm gen.
4680 double ext_roots_start = os::elapsedTime();
4681 double closure_app_time_sec = 0.0;
4683 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4684 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4685 buf_scan_perm.set_generation(perm_gen());
4687 // Walk the code cache w/o buffering, because StarTask cannot handle
4688 // unaligned oop locations.
4689 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4691 process_strong_roots(false, // no scoping; this is parallel code
4692 collecting_perm_gen, so,
4693 &buf_scan_non_heap_roots,
4694 &eager_scan_code_roots,
4695 &buf_scan_perm);
4697 // Finish up any enqueued closure apps.
4698 buf_scan_non_heap_roots.done();
4699 buf_scan_perm.done();
4700 double ext_roots_end = os::elapsedTime();
4701 g1_policy()->reset_obj_copy_time(worker_i);
4702 double obj_copy_time_sec =
4703 buf_scan_non_heap_roots.closure_app_seconds() +
4704 buf_scan_perm.closure_app_seconds();
4705 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4706 double ext_root_time_ms =
4707 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4708 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4710 // Scan strong roots in mark stack.
4711 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4712 concurrent_mark()->oops_do(scan_non_heap_roots);
4713 }
4714 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4715 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4717 // XXX What should this be doing in the parallel case?
4718 g1_policy()->record_collection_pause_end_CH_strong_roots();
4719 // Now scan the complement of the collection set.
4720 if (scan_rs != NULL) {
4721 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4722 }
4723 // Finish with the ref_processor roots.
4724 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4725 // We need to treat the discovered reference lists as roots and
4726 // keep entries (which are added by the marking threads) on them
4727 // live until they can be processed at the end of marking.
4728 ref_processor()->weak_oops_do(scan_non_heap_roots);
4729 ref_processor()->oops_do(scan_non_heap_roots);
4730 }
4731 g1_policy()->record_collection_pause_end_G1_strong_roots();
4732 _process_strong_tasks->all_tasks_completed();
4733 }
4735 void
4736 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4737 OopClosure* non_root_closure) {
4738 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4739 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4740 }
4743 class SaveMarksClosure: public HeapRegionClosure {
4744 public:
4745 bool doHeapRegion(HeapRegion* r) {
4746 r->save_marks();
4747 return false;
4748 }
4749 };
4751 void G1CollectedHeap::save_marks() {
4752 if (!CollectedHeap::use_parallel_gc_threads()) {
4753 SaveMarksClosure sm;
4754 heap_region_iterate(&sm);
4755 }
4756 // We do this even in the parallel case
4757 perm_gen()->save_marks();
4758 }
4760 void G1CollectedHeap::evacuate_collection_set() {
4761 set_evacuation_failed(false);
4763 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4764 concurrent_g1_refine()->set_use_cache(false);
4765 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4767 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4768 set_par_threads(n_workers);
4769 G1ParTask g1_par_task(this, n_workers, _task_queues);
4771 init_for_evac_failure(NULL);
4773 rem_set()->prepare_for_younger_refs_iterate(true);
4775 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4776 double start_par = os::elapsedTime();
4777 if (G1CollectedHeap::use_parallel_gc_threads()) {
4778 // The individual threads will set their evac-failure closures.
4779 StrongRootsScope srs(this);
4780 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
4781 workers()->run_task(&g1_par_task);
4782 } else {
4783 StrongRootsScope srs(this);
4784 g1_par_task.work(0);
4785 }
4787 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4788 g1_policy()->record_par_time(par_time);
4789 set_par_threads(0);
4790 // Is this the right thing to do here? We don't save marks
4791 // on individual heap regions when we allocate from
4792 // them in parallel, so this seems like the correct place for this.
4793 retire_all_alloc_regions();
4795 // Weak root processing.
4796 // Note: when JSR 292 is enabled and code blobs can contain
4797 // non-perm oops then we will need to process the code blobs
4798 // here too.
4799 {
4800 G1IsAliveClosure is_alive(this);
4801 G1KeepAliveClosure keep_alive(this);
4802 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4803 }
4804 release_gc_alloc_regions(false /* totally */);
4805 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4807 concurrent_g1_refine()->clear_hot_cache();
4808 concurrent_g1_refine()->set_use_cache(true);
4810 finalize_for_evac_failure();
4812 // Must do this before removing self-forwarding pointers, which clears
4813 // the per-region evac-failure flags.
4814 concurrent_mark()->complete_marking_in_collection_set();
4816 if (evacuation_failed()) {
4817 remove_self_forwarding_pointers();
4818 if (PrintGCDetails) {
4819 gclog_or_tty->print(" (to-space overflow)");
4820 } else if (PrintGC) {
4821 gclog_or_tty->print("--");
4822 }
4823 }
4825 if (G1DeferredRSUpdate) {
4826 RedirtyLoggedCardTableEntryFastClosure redirty;
4827 dirty_card_queue_set().set_closure(&redirty);
4828 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4830 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4831 dcq.merge_bufferlists(&dirty_card_queue_set());
4832 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4833 }
4834 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4835 }
4837 void G1CollectedHeap::free_region(HeapRegion* hr) {
4838 size_t pre_used = 0;
4839 size_t cleared_h_regions = 0;
4840 size_t freed_regions = 0;
4841 UncleanRegionList local_list;
4843 HeapWord* start = hr->bottom();
4844 HeapWord* end = hr->prev_top_at_mark_start();
4845 size_t used_bytes = hr->used();
4846 size_t live_bytes = hr->max_live_bytes();
4847 if (used_bytes > 0) {
4848 guarantee( live_bytes <= used_bytes, "invariant" );
4849 } else {
4850 guarantee( live_bytes == 0, "invariant" );
4851 }
4853 size_t garbage_bytes = used_bytes - live_bytes;
4854 if (garbage_bytes > 0)
4855 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4857 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4858 &local_list);
4859 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4860 &local_list);
4861 }
4863 void
4864 G1CollectedHeap::free_region_work(HeapRegion* hr,
4865 size_t& pre_used,
4866 size_t& cleared_h_regions,
4867 size_t& freed_regions,
4868 UncleanRegionList* list,
4869 bool par) {
4870 pre_used += hr->used();
4871 if (hr->isHumongous()) {
4872 assert(hr->startsHumongous(),
4873 "Only the start of a humongous region should be freed.");
4874 int ind = _hrs->find(hr);
4875 assert(ind != -1, "Should have an index.");
4876 // Clear the start region.
4877 hr->hr_clear(par, true /*clear_space*/);
4878 list->insert_before_head(hr);
4879 cleared_h_regions++;
4880 freed_regions++;
4881 // Clear any continued regions.
4882 ind++;
4883 while ((size_t)ind < n_regions()) {
4884 HeapRegion* hrc = _hrs->at(ind);
4885 if (!hrc->continuesHumongous()) break;
4886 // Otherwise, does continue the H region.
4887 assert(hrc->humongous_start_region() == hr, "Huh?");
4888 hrc->hr_clear(par, true /*clear_space*/);
4889 cleared_h_regions++;
4890 freed_regions++;
4891 list->insert_before_head(hrc);
4892 ind++;
4893 }
4894 } else {
4895 hr->hr_clear(par, true /*clear_space*/);
4896 list->insert_before_head(hr);
4897 freed_regions++;
4898 // If we're using clear2, this should not be enabled.
4899 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4900 }
4901 }
4903 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4904 size_t cleared_h_regions,
4905 size_t freed_regions,
4906 UncleanRegionList* list) {
4907 if (list != NULL && list->sz() > 0) {
4908 prepend_region_list_on_unclean_list(list);
4909 }
4910 // Acquire a lock, if we're parallel, to update possibly-shared
4911 // variables.
4912 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4913 {
4914 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4915 _summary_bytes_used -= pre_used;
4916 _num_humongous_regions -= (int) cleared_h_regions;
4917 _free_regions += freed_regions;
4918 }
4919 }
4922 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4923 while (list != NULL) {
4924 guarantee( list->is_young(), "invariant" );
4926 HeapWord* bottom = list->bottom();
4927 HeapWord* end = list->end();
4928 MemRegion mr(bottom, end);
4929 ct_bs->dirty(mr);
4931 list = list->get_next_young_region();
4932 }
4933 }
4936 class G1ParCleanupCTTask : public AbstractGangTask {
4937 CardTableModRefBS* _ct_bs;
4938 G1CollectedHeap* _g1h;
4939 HeapRegion* volatile _su_head;
4940 public:
4941 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4942 G1CollectedHeap* g1h,
4943 HeapRegion* survivor_list) :
4944 AbstractGangTask("G1 Par Cleanup CT Task"),
4945 _ct_bs(ct_bs),
4946 _g1h(g1h),
4947 _su_head(survivor_list)
4948 { }
4950 void work(int i) {
4951 HeapRegion* r;
4952 while (r = _g1h->pop_dirty_cards_region()) {
4953 clear_cards(r);
4954 }
4955 // Redirty the cards of the survivor regions.
4956 dirty_list(&this->_su_head);
4957 }
4959 void clear_cards(HeapRegion* r) {
4960 // Cards for Survivor regions will be dirtied later.
4961 if (!r->is_survivor()) {
4962 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4963 }
4964 }
4966 void dirty_list(HeapRegion* volatile * head_ptr) {
4967 HeapRegion* head;
4968 do {
4969 // Pop region off the list.
4970 head = *head_ptr;
4971 if (head != NULL) {
4972 HeapRegion* r = (HeapRegion*)
4973 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4974 if (r == head) {
4975 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4976 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4977 }
4978 }
4979 } while (*head_ptr != NULL);
4980 }
4981 };
4984 #ifndef PRODUCT
4985 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4986 CardTableModRefBS* _ct_bs;
4987 public:
4988 G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
4989 : _ct_bs(ct_bs)
4990 { }
4991 virtual bool doHeapRegion(HeapRegion* r)
4992 {
4993 MemRegion mr(r->bottom(), r->end());
4994 if (r->is_survivor()) {
4995 _ct_bs->verify_dirty_region(mr);
4996 } else {
4997 _ct_bs->verify_clean_region(mr);
4998 }
4999 return false;
5000 }
5001 };
5002 #endif
5004 void G1CollectedHeap::cleanUpCardTable() {
5005 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5006 double start = os::elapsedTime();
5008 // Iterate over the dirty cards region list.
5009 G1ParCleanupCTTask cleanup_task(ct_bs, this,
5010 _young_list->first_survivor_region());
5012 if (ParallelGCThreads > 0) {
5013 set_par_threads(workers()->total_workers());
5014 workers()->run_task(&cleanup_task);
5015 set_par_threads(0);
5016 } else {
5017 while (_dirty_cards_region_list) {
5018 HeapRegion* r = _dirty_cards_region_list;
5019 cleanup_task.clear_cards(r);
5020 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5021 if (_dirty_cards_region_list == r) {
5022 // The last region.
5023 _dirty_cards_region_list = NULL;
5024 }
5025 r->set_next_dirty_cards_region(NULL);
5026 }
5027 // now, redirty the cards of the survivor regions
5028 // (it seemed faster to do it this way, instead of iterating over
5029 // all regions and then clearing / dirtying as appropriate)
5030 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
5031 }
5033 double elapsed = os::elapsedTime() - start;
5034 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
5035 #ifndef PRODUCT
5036 if (G1VerifyCTCleanup || VerifyAfterGC) {
5037 G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
5038 heap_region_iterate(&cleanup_verifier);
5039 }
5040 #endif
5041 }
5043 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5044 double young_time_ms = 0.0;
5045 double non_young_time_ms = 0.0;
5047 // Since the collection set is a superset of the the young list,
5048 // all we need to do to clear the young list is clear its
5049 // head and length, and unlink any young regions in the code below
5050 _young_list->clear();
5052 G1CollectorPolicy* policy = g1_policy();
5054 double start_sec = os::elapsedTime();
5055 bool non_young = true;
5057 HeapRegion* cur = cs_head;
5058 int age_bound = -1;
5059 size_t rs_lengths = 0;
5061 while (cur != NULL) {
5062 if (non_young) {
5063 if (cur->is_young()) {
5064 double end_sec = os::elapsedTime();
5065 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5066 non_young_time_ms += elapsed_ms;
5068 start_sec = os::elapsedTime();
5069 non_young = false;
5070 }
5071 } else {
5072 if (!cur->is_on_free_list()) {
5073 double end_sec = os::elapsedTime();
5074 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5075 young_time_ms += elapsed_ms;
5077 start_sec = os::elapsedTime();
5078 non_young = true;
5079 }
5080 }
5082 rs_lengths += cur->rem_set()->occupied();
5084 HeapRegion* next = cur->next_in_collection_set();
5085 assert(cur->in_collection_set(), "bad CS");
5086 cur->set_next_in_collection_set(NULL);
5087 cur->set_in_collection_set(false);
5089 if (cur->is_young()) {
5090 int index = cur->young_index_in_cset();
5091 guarantee( index != -1, "invariant" );
5092 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
5093 size_t words_survived = _surviving_young_words[index];
5094 cur->record_surv_words_in_group(words_survived);
5096 // At this point the we have 'popped' cur from the collection set
5097 // (linked via next_in_collection_set()) but it is still in the
5098 // young list (linked via next_young_region()). Clear the
5099 // _next_young_region field.
5100 cur->set_next_young_region(NULL);
5101 } else {
5102 int index = cur->young_index_in_cset();
5103 guarantee( index == -1, "invariant" );
5104 }
5106 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5107 (!cur->is_young() && cur->young_index_in_cset() == -1),
5108 "invariant" );
5110 if (!cur->evacuation_failed()) {
5111 // And the region is empty.
5112 assert(!cur->is_empty(),
5113 "Should not have empty regions in a CS.");
5114 free_region(cur);
5115 } else {
5116 cur->uninstall_surv_rate_group();
5117 if (cur->is_young())
5118 cur->set_young_index_in_cset(-1);
5119 cur->set_not_young();
5120 cur->set_evacuation_failed(false);
5121 }
5122 cur = next;
5123 }
5125 policy->record_max_rs_lengths(rs_lengths);
5126 policy->cset_regions_freed();
5128 double end_sec = os::elapsedTime();
5129 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5130 if (non_young)
5131 non_young_time_ms += elapsed_ms;
5132 else
5133 young_time_ms += elapsed_ms;
5135 policy->record_young_free_cset_time_ms(young_time_ms);
5136 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5137 }
5139 // This routine is similar to the above but does not record
5140 // any policy statistics or update free lists; we are abandoning
5141 // the current incremental collection set in preparation of a
5142 // full collection. After the full GC we will start to build up
5143 // the incremental collection set again.
5144 // This is only called when we're doing a full collection
5145 // and is immediately followed by the tearing down of the young list.
5147 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5148 HeapRegion* cur = cs_head;
5150 while (cur != NULL) {
5151 HeapRegion* next = cur->next_in_collection_set();
5152 assert(cur->in_collection_set(), "bad CS");
5153 cur->set_next_in_collection_set(NULL);
5154 cur->set_in_collection_set(false);
5155 cur->set_young_index_in_cset(-1);
5156 cur = next;
5157 }
5158 }
5160 HeapRegion*
5161 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
5162 assert(ZF_mon->owned_by_self(), "Precondition");
5163 HeapRegion* res = pop_unclean_region_list_locked();
5164 if (res != NULL) {
5165 assert(!res->continuesHumongous() &&
5166 res->zero_fill_state() != HeapRegion::Allocated,
5167 "Only free regions on unclean list.");
5168 if (zero_filled) {
5169 res->ensure_zero_filled_locked();
5170 res->set_zero_fill_allocated();
5171 }
5172 }
5173 return res;
5174 }
5176 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
5177 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
5178 return alloc_region_from_unclean_list_locked(zero_filled);
5179 }
5181 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
5182 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5183 put_region_on_unclean_list_locked(r);
5184 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
5185 }
5187 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
5188 MutexLockerEx x(Cleanup_mon);
5189 set_unclean_regions_coming_locked(b);
5190 }
5192 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
5193 assert(Cleanup_mon->owned_by_self(), "Precondition");
5194 _unclean_regions_coming = b;
5195 // Wake up mutator threads that might be waiting for completeCleanup to
5196 // finish.
5197 if (!b) Cleanup_mon->notify_all();
5198 }
5200 void G1CollectedHeap::wait_for_cleanup_complete() {
5201 assert_not_at_safepoint();
5202 MutexLockerEx x(Cleanup_mon);
5203 wait_for_cleanup_complete_locked();
5204 }
5206 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
5207 assert(Cleanup_mon->owned_by_self(), "precondition");
5208 while (_unclean_regions_coming) {
5209 Cleanup_mon->wait();
5210 }
5211 }
5213 void
5214 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
5215 assert(ZF_mon->owned_by_self(), "precondition.");
5216 #ifdef ASSERT
5217 if (r->is_gc_alloc_region()) {
5218 ResourceMark rm;
5219 stringStream region_str;
5220 print_on(®ion_str);
5221 assert(!r->is_gc_alloc_region(), err_msg("Unexpected GC allocation region: %s",
5222 region_str.as_string()));
5223 }
5224 #endif
5225 _unclean_region_list.insert_before_head(r);
5226 }
5228 void
5229 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
5230 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5231 prepend_region_list_on_unclean_list_locked(list);
5232 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
5233 }
5235 void
5236 G1CollectedHeap::
5237 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
5238 assert(ZF_mon->owned_by_self(), "precondition.");
5239 _unclean_region_list.prepend_list(list);
5240 }
5242 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
5243 assert(ZF_mon->owned_by_self(), "precondition.");
5244 HeapRegion* res = _unclean_region_list.pop();
5245 if (res != NULL) {
5246 // Inform ZF thread that there's a new unclean head.
5247 if (_unclean_region_list.hd() != NULL && should_zf())
5248 ZF_mon->notify_all();
5249 }
5250 return res;
5251 }
5253 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
5254 assert(ZF_mon->owned_by_self(), "precondition.");
5255 return _unclean_region_list.hd();
5256 }
5259 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
5260 assert(ZF_mon->owned_by_self(), "Precondition");
5261 HeapRegion* r = peek_unclean_region_list_locked();
5262 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
5263 // Result of below must be equal to "r", since we hold the lock.
5264 (void)pop_unclean_region_list_locked();
5265 put_free_region_on_list_locked(r);
5266 return true;
5267 } else {
5268 return false;
5269 }
5270 }
5272 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
5273 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5274 return move_cleaned_region_to_free_list_locked();
5275 }
5278 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
5279 assert(ZF_mon->owned_by_self(), "precondition.");
5280 assert(_free_region_list_size == free_region_list_length(), "Inv");
5281 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
5282 "Regions on free list must be zero filled");
5283 assert(!r->isHumongous(), "Must not be humongous.");
5284 assert(r->is_empty(), "Better be empty");
5285 assert(!r->is_on_free_list(),
5286 "Better not already be on free list");
5287 assert(!r->is_on_unclean_list(),
5288 "Better not already be on unclean list");
5289 r->set_on_free_list(true);
5290 r->set_next_on_free_list(_free_region_list);
5291 _free_region_list = r;
5292 _free_region_list_size++;
5293 assert(_free_region_list_size == free_region_list_length(), "Inv");
5294 }
5296 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
5297 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5298 put_free_region_on_list_locked(r);
5299 }
5301 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
5302 assert(ZF_mon->owned_by_self(), "precondition.");
5303 assert(_free_region_list_size == free_region_list_length(), "Inv");
5304 HeapRegion* res = _free_region_list;
5305 if (res != NULL) {
5306 _free_region_list = res->next_from_free_list();
5307 _free_region_list_size--;
5308 res->set_on_free_list(false);
5309 res->set_next_on_free_list(NULL);
5310 assert(_free_region_list_size == free_region_list_length(), "Inv");
5311 }
5312 return res;
5313 }
5316 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
5317 // By self, or on behalf of self.
5318 assert(Heap_lock->is_locked(), "Precondition");
5319 HeapRegion* res = NULL;
5320 bool first = true;
5321 while (res == NULL) {
5322 if (zero_filled || !first) {
5323 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5324 res = pop_free_region_list_locked();
5325 if (res != NULL) {
5326 assert(!res->zero_fill_is_allocated(),
5327 "No allocated regions on free list.");
5328 res->set_zero_fill_allocated();
5329 } else if (!first) {
5330 break; // We tried both, time to return NULL.
5331 }
5332 }
5334 if (res == NULL) {
5335 res = alloc_region_from_unclean_list(zero_filled);
5336 }
5337 assert(res == NULL ||
5338 !zero_filled ||
5339 res->zero_fill_is_allocated(),
5340 "We must have allocated the region we're returning");
5341 first = false;
5342 }
5343 return res;
5344 }
5346 void G1CollectedHeap::remove_allocated_regions_from_lists() {
5347 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5348 {
5349 HeapRegion* prev = NULL;
5350 HeapRegion* cur = _unclean_region_list.hd();
5351 while (cur != NULL) {
5352 HeapRegion* next = cur->next_from_unclean_list();
5353 if (cur->zero_fill_is_allocated()) {
5354 // Remove from the list.
5355 if (prev == NULL) {
5356 (void)_unclean_region_list.pop();
5357 } else {
5358 _unclean_region_list.delete_after(prev);
5359 }
5360 cur->set_on_unclean_list(false);
5361 cur->set_next_on_unclean_list(NULL);
5362 } else {
5363 prev = cur;
5364 }
5365 cur = next;
5366 }
5367 assert(_unclean_region_list.sz() == unclean_region_list_length(),
5368 "Inv");
5369 }
5371 {
5372 HeapRegion* prev = NULL;
5373 HeapRegion* cur = _free_region_list;
5374 while (cur != NULL) {
5375 HeapRegion* next = cur->next_from_free_list();
5376 if (cur->zero_fill_is_allocated()) {
5377 // Remove from the list.
5378 if (prev == NULL) {
5379 _free_region_list = cur->next_from_free_list();
5380 } else {
5381 prev->set_next_on_free_list(cur->next_from_free_list());
5382 }
5383 cur->set_on_free_list(false);
5384 cur->set_next_on_free_list(NULL);
5385 _free_region_list_size--;
5386 } else {
5387 prev = cur;
5388 }
5389 cur = next;
5390 }
5391 assert(_free_region_list_size == free_region_list_length(), "Inv");
5392 }
5393 }
5395 bool G1CollectedHeap::verify_region_lists() {
5396 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5397 return verify_region_lists_locked();
5398 }
5400 bool G1CollectedHeap::verify_region_lists_locked() {
5401 HeapRegion* unclean = _unclean_region_list.hd();
5402 while (unclean != NULL) {
5403 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
5404 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
5405 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
5406 "Everything else is possible.");
5407 unclean = unclean->next_from_unclean_list();
5408 }
5409 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
5411 HeapRegion* free_r = _free_region_list;
5412 while (free_r != NULL) {
5413 assert(free_r->is_on_free_list(), "Well, it is!");
5414 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
5415 switch (free_r->zero_fill_state()) {
5416 case HeapRegion::NotZeroFilled:
5417 case HeapRegion::ZeroFilling:
5418 guarantee(false, "Should not be on free list.");
5419 break;
5420 default:
5421 // Everything else is possible.
5422 break;
5423 }
5424 free_r = free_r->next_from_free_list();
5425 }
5426 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
5427 // If we didn't do an assertion...
5428 return true;
5429 }
5431 size_t G1CollectedHeap::free_region_list_length() {
5432 assert(ZF_mon->owned_by_self(), "precondition.");
5433 size_t len = 0;
5434 HeapRegion* cur = _free_region_list;
5435 while (cur != NULL) {
5436 len++;
5437 cur = cur->next_from_free_list();
5438 }
5439 return len;
5440 }
5442 size_t G1CollectedHeap::unclean_region_list_length() {
5443 assert(ZF_mon->owned_by_self(), "precondition.");
5444 return _unclean_region_list.length();
5445 }
5447 size_t G1CollectedHeap::n_regions() {
5448 return _hrs->length();
5449 }
5451 size_t G1CollectedHeap::max_regions() {
5452 return
5453 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
5454 HeapRegion::GrainBytes;
5455 }
5457 size_t G1CollectedHeap::free_regions() {
5458 /* Possibly-expensive assert.
5459 assert(_free_regions == count_free_regions(),
5460 "_free_regions is off.");
5461 */
5462 return _free_regions;
5463 }
5465 bool G1CollectedHeap::should_zf() {
5466 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
5467 }
5469 class RegionCounter: public HeapRegionClosure {
5470 size_t _n;
5471 public:
5472 RegionCounter() : _n(0) {}
5473 bool doHeapRegion(HeapRegion* r) {
5474 if (r->is_empty()) {
5475 assert(!r->isHumongous(), "H regions should not be empty.");
5476 _n++;
5477 }
5478 return false;
5479 }
5480 int res() { return (int) _n; }
5481 };
5483 size_t G1CollectedHeap::count_free_regions() {
5484 RegionCounter rc;
5485 heap_region_iterate(&rc);
5486 size_t n = rc.res();
5487 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
5488 n--;
5489 return n;
5490 }
5492 size_t G1CollectedHeap::count_free_regions_list() {
5493 size_t n = 0;
5494 size_t o = 0;
5495 ZF_mon->lock_without_safepoint_check();
5496 HeapRegion* cur = _free_region_list;
5497 while (cur != NULL) {
5498 cur = cur->next_from_free_list();
5499 n++;
5500 }
5501 size_t m = unclean_region_list_length();
5502 ZF_mon->unlock();
5503 return n + m;
5504 }
5506 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5507 assert(heap_lock_held_for_gc(),
5508 "the heap lock should already be held by or for this thread");
5509 _young_list->push_region(hr);
5510 g1_policy()->set_region_short_lived(hr);
5511 }
5513 class NoYoungRegionsClosure: public HeapRegionClosure {
5514 private:
5515 bool _success;
5516 public:
5517 NoYoungRegionsClosure() : _success(true) { }
5518 bool doHeapRegion(HeapRegion* r) {
5519 if (r->is_young()) {
5520 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5521 r->bottom(), r->end());
5522 _success = false;
5523 }
5524 return false;
5525 }
5526 bool success() { return _success; }
5527 };
5529 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5530 bool ret = _young_list->check_list_empty(check_sample);
5532 if (check_heap) {
5533 NoYoungRegionsClosure closure;
5534 heap_region_iterate(&closure);
5535 ret = ret && closure.success();
5536 }
5538 return ret;
5539 }
5541 void G1CollectedHeap::empty_young_list() {
5542 assert(heap_lock_held_for_gc(),
5543 "the heap lock should already be held by or for this thread");
5544 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5546 _young_list->empty_list();
5547 }
5549 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5550 bool no_allocs = true;
5551 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5552 HeapRegion* r = _gc_alloc_regions[ap];
5553 no_allocs = r == NULL || r->saved_mark_at_top();
5554 }
5555 return no_allocs;
5556 }
5558 void G1CollectedHeap::retire_all_alloc_regions() {
5559 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5560 HeapRegion* r = _gc_alloc_regions[ap];
5561 if (r != NULL) {
5562 // Check for aliases.
5563 bool has_processed_alias = false;
5564 for (int i = 0; i < ap; ++i) {
5565 if (_gc_alloc_regions[i] == r) {
5566 has_processed_alias = true;
5567 break;
5568 }
5569 }
5570 if (!has_processed_alias) {
5571 retire_alloc_region(r, false /* par */);
5572 }
5573 }
5574 }
5575 }
5578 // Done at the start of full GC.
5579 void G1CollectedHeap::tear_down_region_lists() {
5580 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5581 while (pop_unclean_region_list_locked() != NULL) ;
5582 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
5583 "Postconditions of loop.");
5584 while (pop_free_region_list_locked() != NULL) ;
5585 assert(_free_region_list == NULL, "Postcondition of loop.");
5586 if (_free_region_list_size != 0) {
5587 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
5588 print_on(gclog_or_tty, true /* extended */);
5589 }
5590 assert(_free_region_list_size == 0, "Postconditions of loop.");
5591 }
5594 class RegionResetter: public HeapRegionClosure {
5595 G1CollectedHeap* _g1;
5596 int _n;
5597 public:
5598 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5599 bool doHeapRegion(HeapRegion* r) {
5600 if (r->continuesHumongous()) return false;
5601 if (r->top() > r->bottom()) {
5602 if (r->top() < r->end()) {
5603 Copy::fill_to_words(r->top(),
5604 pointer_delta(r->end(), r->top()));
5605 }
5606 r->set_zero_fill_allocated();
5607 } else {
5608 assert(r->is_empty(), "tautology");
5609 _n++;
5610 switch (r->zero_fill_state()) {
5611 case HeapRegion::NotZeroFilled:
5612 case HeapRegion::ZeroFilling:
5613 _g1->put_region_on_unclean_list_locked(r);
5614 break;
5615 case HeapRegion::Allocated:
5616 r->set_zero_fill_complete();
5617 // no break; go on to put on free list.
5618 case HeapRegion::ZeroFilled:
5619 _g1->put_free_region_on_list_locked(r);
5620 break;
5621 }
5622 }
5623 return false;
5624 }
5626 int getFreeRegionCount() {return _n;}
5627 };
5629 // Done at the end of full GC.
5630 void G1CollectedHeap::rebuild_region_lists() {
5631 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5632 // This needs to go at the end of the full GC.
5633 RegionResetter rs;
5634 heap_region_iterate(&rs);
5635 _free_regions = rs.getFreeRegionCount();
5636 // Tell the ZF thread it may have work to do.
5637 if (should_zf()) ZF_mon->notify_all();
5638 }
5640 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5641 G1CollectedHeap* _g1;
5642 int _n;
5643 public:
5644 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5645 bool doHeapRegion(HeapRegion* r) {
5646 if (r->continuesHumongous()) return false;
5647 if (r->top() > r->bottom()) {
5648 // There are assertions in "set_zero_fill_needed()" below that
5649 // require top() == bottom(), so this is technically illegal.
5650 // We'll skirt the law here, by making that true temporarily.
5651 DEBUG_ONLY(HeapWord* save_top = r->top();
5652 r->set_top(r->bottom()));
5653 r->set_zero_fill_needed();
5654 DEBUG_ONLY(r->set_top(save_top));
5655 }
5656 return false;
5657 }
5658 };
5660 // Done at the start of full GC.
5661 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5662 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5663 // This needs to go at the end of the full GC.
5664 UsedRegionsNeedZeroFillSetter rs;
5665 heap_region_iterate(&rs);
5666 }
5668 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5669 _refine_cte_cl->set_concurrent(concurrent);
5670 }
5672 #ifndef PRODUCT
5674 class PrintHeapRegionClosure: public HeapRegionClosure {
5675 public:
5676 bool doHeapRegion(HeapRegion *r) {
5677 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5678 if (r != NULL) {
5679 if (r->is_on_free_list())
5680 gclog_or_tty->print("Free ");
5681 if (r->is_young())
5682 gclog_or_tty->print("Young ");
5683 if (r->isHumongous())
5684 gclog_or_tty->print("Is Humongous ");
5685 r->print();
5686 }
5687 return false;
5688 }
5689 };
5691 class SortHeapRegionClosure : public HeapRegionClosure {
5692 size_t young_regions,free_regions, unclean_regions;
5693 size_t hum_regions, count;
5694 size_t unaccounted, cur_unclean, cur_alloc;
5695 size_t total_free;
5696 HeapRegion* cur;
5697 public:
5698 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5699 free_regions(0), unclean_regions(0),
5700 hum_regions(0),
5701 count(0), unaccounted(0),
5702 cur_alloc(0), total_free(0)
5703 {}
5704 bool doHeapRegion(HeapRegion *r) {
5705 count++;
5706 if (r->is_on_free_list()) free_regions++;
5707 else if (r->is_on_unclean_list()) unclean_regions++;
5708 else if (r->isHumongous()) hum_regions++;
5709 else if (r->is_young()) young_regions++;
5710 else if (r == cur) cur_alloc++;
5711 else unaccounted++;
5712 return false;
5713 }
5714 void print() {
5715 total_free = free_regions + unclean_regions;
5716 gclog_or_tty->print("%d regions\n", count);
5717 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5718 total_free, free_regions, unclean_regions);
5719 gclog_or_tty->print("%d humongous %d young\n",
5720 hum_regions, young_regions);
5721 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5722 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5723 }
5724 };
5726 void G1CollectedHeap::print_region_counts() {
5727 SortHeapRegionClosure sc(_cur_alloc_region);
5728 PrintHeapRegionClosure cl;
5729 heap_region_iterate(&cl);
5730 heap_region_iterate(&sc);
5731 sc.print();
5732 print_region_accounting_info();
5733 };
5735 bool G1CollectedHeap::regions_accounted_for() {
5736 // TODO: regions accounting for young/survivor/tenured
5737 return true;
5738 }
5740 bool G1CollectedHeap::print_region_accounting_info() {
5741 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5742 free_regions(),
5743 count_free_regions(), count_free_regions_list(),
5744 _free_region_list_size, _unclean_region_list.sz());
5745 gclog_or_tty->print_cr("cur_alloc: %d.",
5746 (_cur_alloc_region == NULL ? 0 : 1));
5747 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5749 // TODO: check regions accounting for young/survivor/tenured
5750 return true;
5751 }
5753 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5754 HeapRegion* hr = heap_region_containing(p);
5755 if (hr == NULL) {
5756 return is_in_permanent(p);
5757 } else {
5758 return hr->is_in(p);
5759 }
5760 }
5761 #endif // !PRODUCT
5763 void G1CollectedHeap::g1_unimplemented() {
5764 // Unimplemented();
5765 }