1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/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"
48
49 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
50
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".
57
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.)
66
67 // Local to this file.
68
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");
86
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 };
96
97
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 };
131
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 };
152
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 };
160
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 }
169
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!");
173
174 hr->set_next_young_region(_head);
175 _head = hr;
176
177 hr->set_young();
178 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
179 ++_length;
180 }
181
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!");
185
186 hr->set_next_young_region(_survivor_head);
187 if (_survivor_head == NULL) {
188 _survivor_tail = hr;
189 }
190 _survivor_head = hr;
191
192 ++_survivor_length;
193 }
194
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 }
204
205 void YoungList::empty_list() {
206 assert(check_list_well_formed(), "young list should be well formed");
207
208 empty_list(_head);
209 _head = NULL;
210 _length = 0;
211
212 empty_list(_survivor_head);
213 _survivor_head = NULL;
214 _survivor_tail = NULL;
215 _survivor_length = 0;
216
217 _last_sampled_rs_lengths = 0;
218
219 assert(check_list_empty(false), "just making sure...");
220 }
221
222 bool YoungList::check_list_well_formed() {
223 bool ret = true;
224
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);
241
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 }
247
248 return ret;
249 }
250
251 bool YoungList::check_list_empty(bool check_sample) {
252 bool ret = true;
253
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 }
270
271 return ret;
272 }
273
274 void
275 YoungList::rs_length_sampling_init() {
276 _sampled_rs_lengths = 0;
277 _curr = _head;
278 }
279
280 bool
281 YoungList::rs_length_sampling_more() {
282 return _curr != NULL;
283 }
284
285 void
286 YoungList::rs_length_sampling_next() {
287 assert( _curr != NULL, "invariant" );
288 size_t rs_length = _curr->rem_set()->occupied();
289
290 _sampled_rs_lengths += rs_length;
291
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 }
299
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 }
306
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");
311
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 */);
315
316 for (HeapRegion* curr = _survivor_head;
317 curr != NULL;
318 curr = curr->get_next_young_region()) {
319 _g1h->g1_policy()->set_region_survivors(curr);
320
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();
327
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 }
335
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.
340
341 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
342
343 assert(check_list_well_formed(), "young list should be well formed");
344 }
345
346 void YoungList::print() {
347 HeapRegion* lists[] = {_head, _survivor_head};
348 const char* names[] = {"YOUNG", "SURVIVOR"};
349
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 }
369
370 gclog_or_tty->print_cr("");
371 }
372
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 }
403
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 }
425
426 void G1CollectedHeap::stop_conc_gc_threads() {
427 _cg1r->stop();
428 _cmThread->stop();
429 }
430
431 #ifdef ASSERT
432 // A region is added to the collection set as it is retired
433 // so an address p can point to a region which will be in the
434 // collection set but has not yet been retired. This method
435 // therefore is only accurate during a GC pause after all
436 // regions have been retired. It is used for debugging
437 // to check if an nmethod has references to objects that can
438 // be move during a partial collection. Though it can be
439 // inaccurate, it is sufficient for G1 because the conservative
440 // implementation of is_scavengable() for G1 will indicate that
441 // all nmethods must be scanned during a partial collection.
442 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
443 HeapRegion* hr = heap_region_containing(p);
444 return hr != NULL && hr->in_collection_set();
445 }
446 #endif
447
448 // Returns true if the reference points to an object that
449 // can move in an incremental collecction.
450 bool G1CollectedHeap::is_scavengable(const void* p) {
451 G1CollectedHeap* g1h = G1CollectedHeap::heap();
452 G1CollectorPolicy* g1p = g1h->g1_policy();
453 HeapRegion* hr = heap_region_containing(p);
454 if (hr == NULL) {
455 // perm gen (or null)
456 return false;
457 } else {
458 return !hr->isHumongous();
459 }
460 }
461
462 void G1CollectedHeap::check_ct_logs_at_safepoint() {
463 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
464 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
465
466 // Count the dirty cards at the start.
467 CountNonCleanMemRegionClosure count1(this);
468 ct_bs->mod_card_iterate(&count1);
469 int orig_count = count1.n();
470
471 // First clear the logged cards.
472 ClearLoggedCardTableEntryClosure clear;
473 dcqs.set_closure(&clear);
474 dcqs.apply_closure_to_all_completed_buffers();
475 dcqs.iterate_closure_all_threads(false);
476 clear.print_histo();
477
478 // Now ensure that there's no dirty cards.
479 CountNonCleanMemRegionClosure count2(this);
480 ct_bs->mod_card_iterate(&count2);
481 if (count2.n() != 0) {
482 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
483 count2.n(), orig_count);
484 }
485 guarantee(count2.n() == 0, "Card table should be clean.");
486
487 RedirtyLoggedCardTableEntryClosure redirty;
488 JavaThread::dirty_card_queue_set().set_closure(&redirty);
489 dcqs.apply_closure_to_all_completed_buffers();
490 dcqs.iterate_closure_all_threads(false);
491 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
492 clear.calls(), orig_count);
493 guarantee(redirty.calls() == clear.calls(),
494 "Or else mechanism is broken.");
495
496 CountNonCleanMemRegionClosure count3(this);
497 ct_bs->mod_card_iterate(&count3);
498 if (count3.n() != orig_count) {
499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
500 orig_count, count3.n());
501 guarantee(count3.n() >= orig_count, "Should have restored them all.");
502 }
503
504 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
505 }
506
507 // Private class members.
508
509 G1CollectedHeap* G1CollectedHeap::_g1h;
510
511 // Private methods.
512
513 HeapRegion*
514 G1CollectedHeap::new_region_try_secondary_free_list() {
515 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
516 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
517 if (!_secondary_free_list.is_empty()) {
518 if (G1ConcRegionFreeingVerbose) {
519 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
520 "secondary_free_list has "SIZE_FORMAT" entries",
521 _secondary_free_list.length());
522 }
523 // It looks as if there are free regions available on the
524 // secondary_free_list. Let's move them to the free_list and try
525 // again to allocate from it.
526 append_secondary_free_list();
527
528 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
529 "empty we should have moved at least one entry to the free_list");
530 HeapRegion* res = _free_list.remove_head();
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "allocated "HR_FORMAT" from secondary_free_list",
534 HR_FORMAT_PARAMS(res));
535 }
536 return res;
537 }
538
539 // Wait here until we get notifed either when (a) there are no
540 // more free regions coming or (b) some regions have been moved on
541 // the secondary_free_list.
542 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
543 }
544
545 if (G1ConcRegionFreeingVerbose) {
546 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
547 "could not allocate from secondary_free_list");
548 }
549 return NULL;
550 }
551
552 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
553 assert(!isHumongous(word_size) ||
554 word_size <= (size_t) HeapRegion::GrainWords,
555 "the only time we use this to allocate a humongous region is "
556 "when we are allocating a single humongous region");
557
558 HeapRegion* res;
559 if (G1StressConcRegionFreeing) {
560 if (!_secondary_free_list.is_empty()) {
561 if (G1ConcRegionFreeingVerbose) {
562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
563 "forced to look at the secondary_free_list");
564 }
565 res = new_region_try_secondary_free_list();
566 if (res != NULL) {
567 return res;
568 }
569 }
570 }
571 res = _free_list.remove_head_or_null();
572 if (res == NULL) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "res == NULL, trying the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list();
578 }
579 if (res == NULL && do_expand) {
580 if (expand(word_size * HeapWordSize)) {
581 // Even though the heap was expanded, it might not have reached
582 // the desired size. So, we cannot assume that the allocation
583 // will succeed.
584 res = _free_list.remove_head_or_null();
585 }
586 }
587 return res;
588 }
589
590 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
591 size_t word_size) {
592 assert(isHumongous(word_size), "word_size should be humongous");
593 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
594
595 size_t first = G1_NULL_HRS_INDEX;
596 if (num_regions == 1) {
597 // Only one region to allocate, no need to go through the slower
598 // path. The caller will attempt the expasion if this fails, so
599 // let's not try to expand here too.
600 HeapRegion* hr = new_region(word_size, false /* do_expand */);
601 if (hr != NULL) {
602 first = hr->hrs_index();
603 } else {
604 first = G1_NULL_HRS_INDEX;
605 }
606 } else {
607 // We can't allocate humongous regions while cleanupComplete() is
608 // running, since some of the regions we find to be empty might not
609 // yet be added to the free list and it is not straightforward to
610 // know which list they are on so that we can remove them. Note
611 // that we only need to do this if we need to allocate more than
612 // one region to satisfy the current humongous allocation
613 // request. If we are only allocating one region we use the common
614 // region allocation code (see above).
615 wait_while_free_regions_coming();
616 append_secondary_free_list_if_not_empty_with_lock();
617
618 if (free_regions() >= num_regions) {
619 first = _hrs.find_contiguous(num_regions);
620 if (first != G1_NULL_HRS_INDEX) {
621 for (size_t i = first; i < first + num_regions; ++i) {
622 HeapRegion* hr = region_at(i);
623 assert(hr->is_empty(), "sanity");
624 assert(is_on_master_free_list(hr), "sanity");
625 hr->set_pending_removal(true);
626 }
627 _free_list.remove_all_pending(num_regions);
628 }
629 }
630 }
631 return first;
632 }
633
634 HeapWord*
635 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first,
636 size_t num_regions,
637 size_t word_size) {
638 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
639 assert(isHumongous(word_size), "word_size should be humongous");
640 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
641
642 // Index of last region in the series + 1.
643 size_t last = first + num_regions;
644
645 // We need to initialize the region(s) we just discovered. This is
646 // a bit tricky given that it can happen concurrently with
647 // refinement threads refining cards on these regions and
648 // potentially wanting to refine the BOT as they are scanning
649 // those cards (this can happen shortly after a cleanup; see CR
650 // 6991377). So we have to set up the region(s) carefully and in
651 // a specific order.
652
653 // The word size sum of all the regions we will allocate.
654 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
655 assert(word_size <= word_size_sum, "sanity");
656
657 // This will be the "starts humongous" region.
658 HeapRegion* first_hr = region_at(first);
659 // The header of the new object will be placed at the bottom of
660 // the first region.
661 HeapWord* new_obj = first_hr->bottom();
662 // This will be the new end of the first region in the series that
663 // should also match the end of the last region in the seriers.
664 HeapWord* new_end = new_obj + word_size_sum;
665 // This will be the new top of the first region that will reflect
666 // this allocation.
667 HeapWord* new_top = new_obj + word_size;
668
669 // First, we need to zero the header of the space that we will be
670 // allocating. When we update top further down, some refinement
671 // threads might try to scan the region. By zeroing the header we
672 // ensure that any thread that will try to scan the region will
673 // come across the zero klass word and bail out.
674 //
675 // NOTE: It would not have been correct to have used
676 // CollectedHeap::fill_with_object() and make the space look like
677 // an int array. The thread that is doing the allocation will
678 // later update the object header to a potentially different array
679 // type and, for a very short period of time, the klass and length
680 // fields will be inconsistent. This could cause a refinement
681 // thread to calculate the object size incorrectly.
682 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
683
684 // We will set up the first region as "starts humongous". This
685 // will also update the BOT covering all the regions to reflect
686 // that there is a single object that starts at the bottom of the
687 // first region.
688 first_hr->set_startsHumongous(new_top, new_end);
689
690 // Then, if there are any, we will set up the "continues
691 // humongous" regions.
692 HeapRegion* hr = NULL;
693 for (size_t i = first + 1; i < last; ++i) {
694 hr = region_at(i);
695 hr->set_continuesHumongous(first_hr);
696 }
697 // If we have "continues humongous" regions (hr != NULL), then the
698 // end of the last one should match new_end.
699 assert(hr == NULL || hr->end() == new_end, "sanity");
700
701 // Up to this point no concurrent thread would have been able to
702 // do any scanning on any region in this series. All the top
703 // fields still point to bottom, so the intersection between
704 // [bottom,top] and [card_start,card_end] will be empty. Before we
705 // update the top fields, we'll do a storestore to make sure that
706 // no thread sees the update to top before the zeroing of the
707 // object header and the BOT initialization.
708 OrderAccess::storestore();
709
710 // Now that the BOT and the object header have been initialized,
711 // we can update top of the "starts humongous" region.
712 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
713 "new_top should be in this region");
714 first_hr->set_top(new_top);
715 if (_hr_printer.is_active()) {
716 HeapWord* bottom = first_hr->bottom();
717 HeapWord* end = first_hr->orig_end();
718 if ((first + 1) == last) {
719 // the series has a single humongous region
720 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
721 } else {
722 // the series has more than one humongous regions
723 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
724 }
725 }
726
727 // Now, we will update the top fields of the "continues humongous"
728 // regions. The reason we need to do this is that, otherwise,
729 // these regions would look empty and this will confuse parts of
730 // G1. For example, the code that looks for a consecutive number
731 // of empty regions will consider them empty and try to
732 // re-allocate them. We can extend is_empty() to also include
733 // !continuesHumongous(), but it is easier to just update the top
734 // fields here. The way we set top for all regions (i.e., top ==
735 // end for all regions but the last one, top == new_top for the
736 // last one) is actually used when we will free up the humongous
737 // region in free_humongous_region().
738 hr = NULL;
739 for (size_t i = first + 1; i < last; ++i) {
740 hr = region_at(i);
741 if ((i + 1) == last) {
742 // last continues humongous region
743 assert(hr->bottom() < new_top && new_top <= hr->end(),
744 "new_top should fall on this region");
745 hr->set_top(new_top);
746 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
747 } else {
748 // not last one
749 assert(new_top > hr->end(), "new_top should be above this region");
750 hr->set_top(hr->end());
751 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
752 }
753 }
754 // If we have continues humongous regions (hr != NULL), then the
755 // end of the last one should match new_end and its top should
756 // match new_top.
757 assert(hr == NULL ||
758 (hr->end() == new_end && hr->top() == new_top), "sanity");
759
760 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
761 _summary_bytes_used += first_hr->used();
762 _humongous_set.add(first_hr);
763
764 return new_obj;
765 }
766
767 // If could fit into free regions w/o expansion, try.
768 // Otherwise, if can expand, do so.
769 // Otherwise, if using ex regions might help, try with ex given back.
770 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
771 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
772
773 verify_region_sets_optional();
774
775 size_t num_regions =
776 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
777 size_t x_size = expansion_regions();
778 size_t fs = _hrs.free_suffix();
779 size_t first = humongous_obj_allocate_find_first(num_regions, word_size);
780 if (first == G1_NULL_HRS_INDEX) {
781 // The only thing we can do now is attempt expansion.
782 if (fs + x_size >= num_regions) {
783 // If the number of regions we're trying to allocate for this
784 // object is at most the number of regions in the free suffix,
785 // then the call to humongous_obj_allocate_find_first() above
786 // should have succeeded and we wouldn't be here.
787 //
788 // We should only be trying to expand when the free suffix is
789 // not sufficient for the object _and_ we have some expansion
790 // room available.
791 assert(num_regions > fs, "earlier allocation should have succeeded");
792
793 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
794 // Even though the heap was expanded, it might not have
795 // reached the desired size. So, we cannot assume that the
796 // allocation will succeed.
797 first = humongous_obj_allocate_find_first(num_regions, word_size);
798 }
799 }
800 }
801
802 HeapWord* result = NULL;
803 if (first != G1_NULL_HRS_INDEX) {
804 result =
805 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
806 assert(result != NULL, "it should always return a valid result");
807 }
808
809 verify_region_sets_optional();
810
811 return result;
812 }
813
814 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
815 assert_heap_not_locked_and_not_at_safepoint();
816 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
817
818 unsigned int dummy_gc_count_before;
819 return attempt_allocation(word_size, &dummy_gc_count_before);
820 }
821
822 HeapWord*
823 G1CollectedHeap::mem_allocate(size_t word_size,
824 bool* gc_overhead_limit_was_exceeded) {
825 assert_heap_not_locked_and_not_at_safepoint();
826
827 // Loop until the allocation is satisified, or unsatisfied after GC.
828 for (int try_count = 1; /* we'll return */; try_count += 1) {
829 unsigned int gc_count_before;
830
831 HeapWord* result = NULL;
832 if (!isHumongous(word_size)) {
833 result = attempt_allocation(word_size, &gc_count_before);
834 } else {
835 result = attempt_allocation_humongous(word_size, &gc_count_before);
836 }
837 if (result != NULL) {
838 return result;
839 }
840
841 // Create the garbage collection operation...
842 VM_G1CollectForAllocation op(gc_count_before, word_size);
843 // ...and get the VM thread to execute it.
844 VMThread::execute(&op);
845
846 if (op.prologue_succeeded() && op.pause_succeeded()) {
847 // If the operation was successful we'll return the result even
848 // if it is NULL. If the allocation attempt failed immediately
849 // after a Full GC, it's unlikely we'll be able to allocate now.
850 HeapWord* result = op.result();
851 if (result != NULL && !isHumongous(word_size)) {
852 // Allocations that take place on VM operations do not do any
853 // card dirtying and we have to do it here. We only have to do
854 // this for non-humongous allocations, though.
855 dirty_young_block(result, word_size);
856 }
857 return result;
858 } else {
859 assert(op.result() == NULL,
860 "the result should be NULL if the VM op did not succeed");
861 }
862
863 // Give a warning if we seem to be looping forever.
864 if ((QueuedAllocationWarningCount > 0) &&
865 (try_count % QueuedAllocationWarningCount == 0)) {
866 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
867 }
868 }
869
870 ShouldNotReachHere();
871 return NULL;
872 }
873
874 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
875 unsigned int *gc_count_before_ret) {
876 // Make sure you read the note in attempt_allocation_humongous().
877
878 assert_heap_not_locked_and_not_at_safepoint();
879 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
880 "be called for humongous allocation requests");
881
882 // We should only get here after the first-level allocation attempt
883 // (attempt_allocation()) failed to allocate.
884
885 // We will loop until a) we manage to successfully perform the
886 // allocation or b) we successfully schedule a collection which
887 // fails to perform the allocation. b) is the only case when we'll
888 // return NULL.
889 HeapWord* result = NULL;
890 for (int try_count = 1; /* we'll return */; try_count += 1) {
891 bool should_try_gc;
892 unsigned int gc_count_before;
893
894 {
895 MutexLockerEx x(Heap_lock);
896
897 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
898 false /* bot_updates */);
899 if (result != NULL) {
900 return result;
901 }
902
903 // If we reach here, attempt_allocation_locked() above failed to
904 // allocate a new region. So the mutator alloc region should be NULL.
905 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
906
907 if (GC_locker::is_active_and_needs_gc()) {
908 if (g1_policy()->can_expand_young_list()) {
909 result = _mutator_alloc_region.attempt_allocation_force(word_size,
910 false /* bot_updates */);
911 if (result != NULL) {
912 return result;
913 }
914 }
915 should_try_gc = false;
916 } else {
917 // Read the GC count while still holding the Heap_lock.
918 gc_count_before = SharedHeap::heap()->total_collections();
919 should_try_gc = true;
920 }
921 }
922
923 if (should_try_gc) {
924 bool succeeded;
925 result = do_collection_pause(word_size, gc_count_before, &succeeded);
926 if (result != NULL) {
927 assert(succeeded, "only way to get back a non-NULL result");
928 return result;
929 }
930
931 if (succeeded) {
932 // If we get here we successfully scheduled a collection which
933 // failed to allocate. No point in trying to allocate
934 // further. We'll just return NULL.
935 MutexLockerEx x(Heap_lock);
936 *gc_count_before_ret = SharedHeap::heap()->total_collections();
937 return NULL;
938 }
939 } else {
940 GC_locker::stall_until_clear();
941 }
942
943 // We can reach here if we were unsuccessul in scheduling a
944 // collection (because another thread beat us to it) or if we were
945 // stalled due to the GC locker. In either can we should retry the
946 // allocation attempt in case another thread successfully
947 // performed a collection and reclaimed enough space. We do the
948 // first attempt (without holding the Heap_lock) here and the
949 // follow-on attempt will be at the start of the next loop
950 // iteration (after taking the Heap_lock).
951 result = _mutator_alloc_region.attempt_allocation(word_size,
952 false /* bot_updates */);
953 if (result != NULL ){
954 return result;
955 }
956
957 // Give a warning if we seem to be looping forever.
958 if ((QueuedAllocationWarningCount > 0) &&
959 (try_count % QueuedAllocationWarningCount == 0)) {
960 warning("G1CollectedHeap::attempt_allocation_slow() "
961 "retries %d times", try_count);
962 }
963 }
964
965 ShouldNotReachHere();
966 return NULL;
967 }
968
969 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
970 unsigned int * gc_count_before_ret) {
971 // The structure of this method has a lot of similarities to
972 // attempt_allocation_slow(). The reason these two were not merged
973 // into a single one is that such a method would require several "if
974 // allocation is not humongous do this, otherwise do that"
975 // conditional paths which would obscure its flow. In fact, an early
976 // version of this code did use a unified method which was harder to
977 // follow and, as a result, it had subtle bugs that were hard to
978 // track down. So keeping these two methods separate allows each to
979 // be more readable. It will be good to keep these two in sync as
980 // much as possible.
981
982 assert_heap_not_locked_and_not_at_safepoint();
983 assert(isHumongous(word_size), "attempt_allocation_humongous() "
984 "should only be called for humongous allocations");
985
986 // We will loop until a) we manage to successfully perform the
987 // allocation or b) we successfully schedule a collection which
988 // fails to perform the allocation. b) is the only case when we'll
989 // return NULL.
990 HeapWord* result = NULL;
991 for (int try_count = 1; /* we'll return */; try_count += 1) {
992 bool should_try_gc;
993 unsigned int gc_count_before;
994
995 {
996 MutexLockerEx x(Heap_lock);
997
998 // Given that humongous objects are not allocated in young
999 // regions, we'll first try to do the allocation without doing a
1000 // collection hoping that there's enough space in the heap.
1001 result = humongous_obj_allocate(word_size);
1002 if (result != NULL) {
1003 return result;
1004 }
1005
1006 if (GC_locker::is_active_and_needs_gc()) {
1007 should_try_gc = false;
1008 } else {
1009 // Read the GC count while still holding the Heap_lock.
1010 gc_count_before = SharedHeap::heap()->total_collections();
1011 should_try_gc = true;
1012 }
1013 }
1014
1015 if (should_try_gc) {
1016 // If we failed to allocate the humongous object, we should try to
1017 // do a collection pause (if we're allowed) in case it reclaims
1018 // enough space for the allocation to succeed after the pause.
1019
1020 bool succeeded;
1021 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1022 if (result != NULL) {
1023 assert(succeeded, "only way to get back a non-NULL result");
1024 return result;
1025 }
1026
1027 if (succeeded) {
1028 // If we get here we successfully scheduled a collection which
1029 // failed to allocate. No point in trying to allocate
1030 // further. We'll just return NULL.
1031 MutexLockerEx x(Heap_lock);
1032 *gc_count_before_ret = SharedHeap::heap()->total_collections();
1033 return NULL;
1034 }
1035 } else {
1036 GC_locker::stall_until_clear();
1037 }
1038
1039 // We can reach here if we were unsuccessul in scheduling a
1040 // collection (because another thread beat us to it) or if we were
1041 // stalled due to the GC locker. In either can we should retry the
1042 // allocation attempt in case another thread successfully
1043 // performed a collection and reclaimed enough space. Give a
1044 // warning if we seem to be looping forever.
1045
1046 if ((QueuedAllocationWarningCount > 0) &&
1047 (try_count % QueuedAllocationWarningCount == 0)) {
1048 warning("G1CollectedHeap::attempt_allocation_humongous() "
1049 "retries %d times", try_count);
1050 }
1051 }
1052
1053 ShouldNotReachHere();
1054 return NULL;
1055 }
1056
1057 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1058 bool expect_null_mutator_alloc_region) {
1059 assert_at_safepoint(true /* should_be_vm_thread */);
1060 assert(_mutator_alloc_region.get() == NULL ||
1061 !expect_null_mutator_alloc_region,
1062 "the current alloc region was unexpectedly found to be non-NULL");
1063
1064 if (!isHumongous(word_size)) {
1065 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1066 false /* bot_updates */);
1067 } else {
1068 return humongous_obj_allocate(word_size);
1069 }
1070
1071 ShouldNotReachHere();
1072 }
1073
1074 class PostMCRemSetClearClosure: public HeapRegionClosure {
1075 ModRefBarrierSet* _mr_bs;
1076 public:
1077 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1078 bool doHeapRegion(HeapRegion* r) {
1079 r->reset_gc_time_stamp();
1080 if (r->continuesHumongous())
1081 return false;
1082 HeapRegionRemSet* hrrs = r->rem_set();
1083 if (hrrs != NULL) hrrs->clear();
1084 // You might think here that we could clear just the cards
1085 // corresponding to the used region. But no: if we leave a dirty card
1086 // in a region we might allocate into, then it would prevent that card
1087 // from being enqueued, and cause it to be missed.
1088 // Re: the performance cost: we shouldn't be doing full GC anyway!
1089 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1090 return false;
1091 }
1092 };
1093
1094
1095 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1096 ModRefBarrierSet* _mr_bs;
1097 public:
1098 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1099 bool doHeapRegion(HeapRegion* r) {
1100 if (r->continuesHumongous()) return false;
1101 if (r->used_region().word_size() != 0) {
1102 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1103 }
1104 return false;
1105 }
1106 };
1107
1108 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1109 G1CollectedHeap* _g1h;
1110 UpdateRSOopClosure _cl;
1111 int _worker_i;
1112 public:
1113 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1114 _cl(g1->g1_rem_set(), worker_i),
1115 _worker_i(worker_i),
1116 _g1h(g1)
1117 { }
1118
1119 bool doHeapRegion(HeapRegion* r) {
1120 if (!r->continuesHumongous()) {
1121 _cl.set_from(r);
1122 r->oop_iterate(&_cl);
1123 }
1124 return false;
1125 }
1126 };
1127
1128 class ParRebuildRSTask: public AbstractGangTask {
1129 G1CollectedHeap* _g1;
1130 public:
1131 ParRebuildRSTask(G1CollectedHeap* g1)
1132 : AbstractGangTask("ParRebuildRSTask"),
1133 _g1(g1)
1134 { }
1135
1136 void work(int i) {
1137 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1138 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1139 HeapRegion::RebuildRSClaimValue);
1140 }
1141 };
1142
1143 class PostCompactionPrinterClosure: public HeapRegionClosure {
1144 private:
1145 G1HRPrinter* _hr_printer;
1146 public:
1147 bool doHeapRegion(HeapRegion* hr) {
1148 assert(!hr->is_young(), "not expecting to find young regions");
1149 // We only generate output for non-empty regions.
1150 if (!hr->is_empty()) {
1151 if (!hr->isHumongous()) {
1152 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1153 } else if (hr->startsHumongous()) {
1154 if (hr->capacity() == (size_t) HeapRegion::GrainBytes) {
1155 // single humongous region
1156 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1157 } else {
1158 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1159 }
1160 } else {
1161 assert(hr->continuesHumongous(), "only way to get here");
1162 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1163 }
1164 }
1165 return false;
1166 }
1167
1168 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1169 : _hr_printer(hr_printer) { }
1170 };
1171
1172 bool G1CollectedHeap::do_collection(bool explicit_gc,
1173 bool clear_all_soft_refs,
1174 size_t word_size) {
1175 assert_at_safepoint(true /* should_be_vm_thread */);
1176
1177 if (GC_locker::check_active_before_gc()) {
1178 return false;
1179 }
1180
1181 SvcGCMarker sgcm(SvcGCMarker::FULL);
1182 ResourceMark rm;
1183
1184 if (PrintHeapAtGC) {
1185 Universe::print_heap_before_gc();
1186 }
1187
1188 verify_region_sets_optional();
1189
1190 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1191 collector_policy()->should_clear_all_soft_refs();
1192
1193 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1194
1195 {
1196 IsGCActiveMark x;
1197
1198 // Timing
1199 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1200 assert(!system_gc || explicit_gc, "invariant");
1201 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1202 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1203 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1204 PrintGC, true, gclog_or_tty);
1205
1206 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1207 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1208
1209 double start = os::elapsedTime();
1210 g1_policy()->record_full_collection_start();
1211
1212 wait_while_free_regions_coming();
1213 append_secondary_free_list_if_not_empty_with_lock();
1214
1215 gc_prologue(true);
1216 increment_total_collections(true /* full gc */);
1217
1218 size_t g1h_prev_used = used();
1219 assert(used() == recalculate_used(), "Should be equal");
1220
1221 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1222 HandleMark hm; // Discard invalid handles created during verification
1223 gclog_or_tty->print(" VerifyBeforeGC:");
1224 prepare_for_verify();
1225 Universe::verify(/* allow dirty */ true,
1226 /* silent */ false,
1227 /* option */ VerifyOption_G1UsePrevMarking);
1228
1229 }
1230 pre_full_gc_dump();
1231
1232 COMPILER2_PRESENT(DerivedPointerTable::clear());
1233
1234 // We want to discover references, but not process them yet.
1235 // This mode is disabled in
1236 // instanceRefKlass::process_discovered_references if the
1237 // generation does some collection work, or
1238 // instanceRefKlass::enqueue_discovered_references if the
1239 // generation returns without doing any work.
1240 ref_processor()->disable_discovery();
1241 ref_processor()->abandon_partial_discovery();
1242 ref_processor()->verify_no_references_recorded();
1243
1244 // Abandon current iterations of concurrent marking and concurrent
1245 // refinement, if any are in progress.
1246 concurrent_mark()->abort();
1247
1248 // Make sure we'll choose a new allocation region afterwards.
1249 release_mutator_alloc_region();
1250 abandon_gc_alloc_regions();
1251 g1_rem_set()->cleanupHRRS();
1252 tear_down_region_lists();
1253
1254 // We should call this after we retire any currently active alloc
1255 // regions so that all the ALLOC / RETIRE events are generated
1256 // before the start GC event.
1257 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1258
1259 // We may have added regions to the current incremental collection
1260 // set between the last GC or pause and now. We need to clear the
1261 // incremental collection set and then start rebuilding it afresh
1262 // after this full GC.
1263 abandon_collection_set(g1_policy()->inc_cset_head());
1264 g1_policy()->clear_incremental_cset();
1265 g1_policy()->stop_incremental_cset_building();
1266
1267 empty_young_list();
1268 g1_policy()->set_full_young_gcs(true);
1269
1270 // See the comment in G1CollectedHeap::ref_processing_init() about
1271 // how reference processing currently works in G1.
1272
1273 // Temporarily make reference _discovery_ single threaded (non-MT).
1274 ReferenceProcessorMTDiscoveryMutator rp_disc_ser(ref_processor(), false);
1275
1276 // Temporarily make refs discovery atomic
1277 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
1278
1279 // Temporarily clear _is_alive_non_header
1280 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
1281
1282 ref_processor()->enable_discovery();
1283 ref_processor()->setup_policy(do_clear_all_soft_refs);
1284 // Do collection work
1285 {
1286 HandleMark hm; // Discard invalid handles created during gc
1287 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
1288 }
1289 assert(free_regions() == 0, "we should not have added any free regions");
1290 rebuild_region_lists();
1291
1292 _summary_bytes_used = recalculate_used();
1293
1294 ref_processor()->enqueue_discovered_references();
1295
1296 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1297
1298 MemoryService::track_memory_usage();
1299
1300 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1301 HandleMark hm; // Discard invalid handles created during verification
1302 gclog_or_tty->print(" VerifyAfterGC:");
1303 prepare_for_verify();
1304 Universe::verify(/* allow dirty */ false,
1305 /* silent */ false,
1306 /* option */ VerifyOption_G1UsePrevMarking);
1307
1308 }
1309 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1310
1311 reset_gc_time_stamp();
1312 // Since everything potentially moved, we will clear all remembered
1313 // sets, and clear all cards. Later we will rebuild remebered
1314 // sets. We will also reset the GC time stamps of the regions.
1315 PostMCRemSetClearClosure rs_clear(mr_bs());
1316 heap_region_iterate(&rs_clear);
1317
1318 // Resize the heap if necessary.
1319 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1320
1321 if (_hr_printer.is_active()) {
1322 // We should do this after we potentially resize the heap so
1323 // that all the COMMIT / UNCOMMIT events are generated before
1324 // the end GC event.
1325
1326 PostCompactionPrinterClosure cl(hr_printer());
1327 heap_region_iterate(&cl);
1328
1329 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1330 }
1331
1332 if (_cg1r->use_cache()) {
1333 _cg1r->clear_and_record_card_counts();
1334 _cg1r->clear_hot_cache();
1335 }
1336
1337 // Rebuild remembered sets of all regions.
1338
1339 if (G1CollectedHeap::use_parallel_gc_threads()) {
1340 ParRebuildRSTask rebuild_rs_task(this);
1341 assert(check_heap_region_claim_values(
1342 HeapRegion::InitialClaimValue), "sanity check");
1343 set_par_threads(workers()->total_workers());
1344 workers()->run_task(&rebuild_rs_task);
1345 set_par_threads(0);
1346 assert(check_heap_region_claim_values(
1347 HeapRegion::RebuildRSClaimValue), "sanity check");
1348 reset_heap_region_claim_values();
1349 } else {
1350 RebuildRSOutOfRegionClosure rebuild_rs(this);
1351 heap_region_iterate(&rebuild_rs);
1352 }
1353
1354 if (PrintGC) {
1355 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1356 }
1357
1358 if (true) { // FIXME
1359 // Ask the permanent generation to adjust size for full collections
1360 perm()->compute_new_size();
1361 }
1362
1363 // Start a new incremental collection set for the next pause
1364 assert(g1_policy()->collection_set() == NULL, "must be");
1365 g1_policy()->start_incremental_cset_building();
1366
1367 // Clear the _cset_fast_test bitmap in anticipation of adding
1368 // regions to the incremental collection set for the next
1369 // evacuation pause.
1370 clear_cset_fast_test();
1371
1372 init_mutator_alloc_region();
1373
1374 double end = os::elapsedTime();
1375 g1_policy()->record_full_collection_end();
1376
1377 #ifdef TRACESPINNING
1378 ParallelTaskTerminator::print_termination_counts();
1379 #endif
1380
1381 gc_epilogue(true);
1382
1383 // Discard all rset updates
1384 JavaThread::dirty_card_queue_set().abandon_logs();
1385 assert(!G1DeferredRSUpdate
1386 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1387 }
1388
1389 _young_list->reset_sampled_info();
1390 // At this point there should be no regions in the
1391 // entire heap tagged as young.
1392 assert( check_young_list_empty(true /* check_heap */),
1393 "young list should be empty at this point");
1394
1395 // Update the number of full collections that have been completed.
1396 increment_full_collections_completed(false /* concurrent */);
1397
1398 _hrs.verify_optional();
1399 verify_region_sets_optional();
1400
1401 if (PrintHeapAtGC) {
1402 Universe::print_heap_after_gc();
1403 }
1404 g1mm()->update_counters();
1405 post_full_gc_dump();
1406
1407 return true;
1408 }
1409
1410 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1411 // do_collection() will return whether it succeeded in performing
1412 // the GC. Currently, there is no facility on the
1413 // do_full_collection() API to notify the caller than the collection
1414 // did not succeed (e.g., because it was locked out by the GC
1415 // locker). So, right now, we'll ignore the return value.
1416 bool dummy = do_collection(true, /* explicit_gc */
1417 clear_all_soft_refs,
1418 0 /* word_size */);
1419 }
1420
1421 // This code is mostly copied from TenuredGeneration.
1422 void
1423 G1CollectedHeap::
1424 resize_if_necessary_after_full_collection(size_t word_size) {
1425 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1426
1427 // Include the current allocation, if any, and bytes that will be
1428 // pre-allocated to support collections, as "used".
1429 const size_t used_after_gc = used();
1430 const size_t capacity_after_gc = capacity();
1431 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1432
1433 // This is enforced in arguments.cpp.
1434 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1435 "otherwise the code below doesn't make sense");
1436
1437 // We don't have floating point command-line arguments
1438 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1439 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1440 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1441 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1442
1443 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1444 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1445
1446 // We have to be careful here as these two calculations can overflow
1447 // 32-bit size_t's.
1448 double used_after_gc_d = (double) used_after_gc;
1449 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1450 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1451
1452 // Let's make sure that they are both under the max heap size, which
1453 // by default will make them fit into a size_t.
1454 double desired_capacity_upper_bound = (double) max_heap_size;
1455 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1456 desired_capacity_upper_bound);
1457 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1458 desired_capacity_upper_bound);
1459
1460 // We can now safely turn them into size_t's.
1461 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1462 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1463
1464 // This assert only makes sense here, before we adjust them
1465 // with respect to the min and max heap size.
1466 assert(minimum_desired_capacity <= maximum_desired_capacity,
1467 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1468 "maximum_desired_capacity = "SIZE_FORMAT,
1469 minimum_desired_capacity, maximum_desired_capacity));
1470
1471 // Should not be greater than the heap max size. No need to adjust
1472 // it with respect to the heap min size as it's a lower bound (i.e.,
1473 // we'll try to make the capacity larger than it, not smaller).
1474 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1475 // Should not be less than the heap min size. No need to adjust it
1476 // with respect to the heap max size as it's an upper bound (i.e.,
1477 // we'll try to make the capacity smaller than it, not greater).
1478 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1479
1480 if (PrintGC && Verbose) {
1481 const double free_percentage =
1482 (double) free_after_gc / (double) capacity_after_gc;
1483 gclog_or_tty->print_cr("Computing new size after full GC ");
1484 gclog_or_tty->print_cr(" "
1485 " minimum_free_percentage: %6.2f",
1486 minimum_free_percentage);
1487 gclog_or_tty->print_cr(" "
1488 " maximum_free_percentage: %6.2f",
1489 maximum_free_percentage);
1490 gclog_or_tty->print_cr(" "
1491 " capacity: %6.1fK"
1492 " minimum_desired_capacity: %6.1fK"
1493 " maximum_desired_capacity: %6.1fK",
1494 (double) capacity_after_gc / (double) K,
1495 (double) minimum_desired_capacity / (double) K,
1496 (double) maximum_desired_capacity / (double) K);
1497 gclog_or_tty->print_cr(" "
1498 " free_after_gc: %6.1fK"
1499 " used_after_gc: %6.1fK",
1500 (double) free_after_gc / (double) K,
1501 (double) used_after_gc / (double) K);
1502 gclog_or_tty->print_cr(" "
1503 " free_percentage: %6.2f",
1504 free_percentage);
1505 }
1506 if (capacity_after_gc < minimum_desired_capacity) {
1507 // Don't expand unless it's significant
1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1509 if (expand(expand_bytes)) {
1510 if (PrintGC && Verbose) {
1511 gclog_or_tty->print_cr(" "
1512 " expanding:"
1513 " max_heap_size: %6.1fK"
1514 " minimum_desired_capacity: %6.1fK"
1515 " expand_bytes: %6.1fK",
1516 (double) max_heap_size / (double) K,
1517 (double) minimum_desired_capacity / (double) K,
1518 (double) expand_bytes / (double) K);
1519 }
1520 }
1521
1522 // No expansion, now see if we want to shrink
1523 } else if (capacity_after_gc > maximum_desired_capacity) {
1524 // Capacity too large, compute shrinking size
1525 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1526 shrink(shrink_bytes);
1527 if (PrintGC && Verbose) {
1528 gclog_or_tty->print_cr(" "
1529 " shrinking:"
1530 " min_heap_size: %6.1fK"
1531 " maximum_desired_capacity: %6.1fK"
1532 " shrink_bytes: %6.1fK",
1533 (double) min_heap_size / (double) K,
1534 (double) maximum_desired_capacity / (double) K,
1535 (double) shrink_bytes / (double) K);
1536 }
1537 }
1538 }
1539
1540
1541 HeapWord*
1542 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1543 bool* succeeded) {
1544 assert_at_safepoint(true /* should_be_vm_thread */);
1545
1546 *succeeded = true;
1547 // Let's attempt the allocation first.
1548 HeapWord* result =
1549 attempt_allocation_at_safepoint(word_size,
1550 false /* expect_null_mutator_alloc_region */);
1551 if (result != NULL) {
1552 assert(*succeeded, "sanity");
1553 return result;
1554 }
1555
1556 // In a G1 heap, we're supposed to keep allocation from failing by
1557 // incremental pauses. Therefore, at least for now, we'll favor
1558 // expansion over collection. (This might change in the future if we can
1559 // do something smarter than full collection to satisfy a failed alloc.)
1560 result = expand_and_allocate(word_size);
1561 if (result != NULL) {
1562 assert(*succeeded, "sanity");
1563 return result;
1564 }
1565
1566 // Expansion didn't work, we'll try to do a Full GC.
1567 bool gc_succeeded = do_collection(false, /* explicit_gc */
1568 false, /* clear_all_soft_refs */
1569 word_size);
1570 if (!gc_succeeded) {
1571 *succeeded = false;
1572 return NULL;
1573 }
1574
1575 // Retry the allocation
1576 result = attempt_allocation_at_safepoint(word_size,
1577 true /* expect_null_mutator_alloc_region */);
1578 if (result != NULL) {
1579 assert(*succeeded, "sanity");
1580 return result;
1581 }
1582
1583 // Then, try a Full GC that will collect all soft references.
1584 gc_succeeded = do_collection(false, /* explicit_gc */
1585 true, /* clear_all_soft_refs */
1586 word_size);
1587 if (!gc_succeeded) {
1588 *succeeded = false;
1589 return NULL;
1590 }
1591
1592 // Retry the allocation once more
1593 result = attempt_allocation_at_safepoint(word_size,
1594 true /* expect_null_mutator_alloc_region */);
1595 if (result != NULL) {
1596 assert(*succeeded, "sanity");
1597 return result;
1598 }
1599
1600 assert(!collector_policy()->should_clear_all_soft_refs(),
1601 "Flag should have been handled and cleared prior to this point");
1602
1603 // What else? We might try synchronous finalization later. If the total
1604 // space available is large enough for the allocation, then a more
1605 // complete compaction phase than we've tried so far might be
1606 // appropriate.
1607 assert(*succeeded, "sanity");
1608 return NULL;
1609 }
1610
1611 // Attempting to expand the heap sufficiently
1612 // to support an allocation of the given "word_size". If
1613 // successful, perform the allocation and return the address of the
1614 // allocated block, or else "NULL".
1615
1616 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1617 assert_at_safepoint(true /* should_be_vm_thread */);
1618
1619 verify_region_sets_optional();
1620
1621 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1622 if (expand(expand_bytes)) {
1623 _hrs.verify_optional();
1624 verify_region_sets_optional();
1625 return attempt_allocation_at_safepoint(word_size,
1626 false /* expect_null_mutator_alloc_region */);
1627 }
1628 return NULL;
1629 }
1630
1631 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1632 HeapWord* new_end) {
1633 assert(old_end != new_end, "don't call this otherwise");
1634 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1635
1636 // Update the committed mem region.
1637 _g1_committed.set_end(new_end);
1638 // Tell the card table about the update.
1639 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1640 // Tell the BOT about the update.
1641 _bot_shared->resize(_g1_committed.word_size());
1642 }
1643
1644 bool G1CollectedHeap::expand(size_t expand_bytes) {
1645 size_t old_mem_size = _g1_storage.committed_size();
1646 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1647 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1648 HeapRegion::GrainBytes);
1649
1650 if (Verbose && PrintGC) {
1651 gclog_or_tty->print("Expanding garbage-first heap from %ldK by %ldK",
1652 old_mem_size/K, aligned_expand_bytes/K);
1653 }
1654
1655 // First commit the memory.
1656 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1657 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1658 if (successful) {
1659 // Then propagate this update to the necessary data structures.
1660 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1661 update_committed_space(old_end, new_end);
1662
1663 FreeRegionList expansion_list("Local Expansion List");
1664 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1665 assert(mr.start() == old_end, "post-condition");
1666 // mr might be a smaller region than what was requested if
1667 // expand_by() was unable to allocate the HeapRegion instances
1668 assert(mr.end() <= new_end, "post-condition");
1669
1670 size_t actual_expand_bytes = mr.byte_size();
1671 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1672 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1673 "post-condition");
1674 if (actual_expand_bytes < aligned_expand_bytes) {
1675 // We could not expand _hrs to the desired size. In this case we
1676 // need to shrink the committed space accordingly.
1677 assert(mr.end() < new_end, "invariant");
1678
1679 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1680 // First uncommit the memory.
1681 _g1_storage.shrink_by(diff_bytes);
1682 // Then propagate this update to the necessary data structures.
1683 update_committed_space(new_end, mr.end());
1684 }
1685 _free_list.add_as_tail(&expansion_list);
1686
1687 if (_hr_printer.is_active()) {
1688 HeapWord* curr = mr.start();
1689 while (curr < mr.end()) {
1690 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1691 _hr_printer.commit(curr, curr_end);
1692 curr = curr_end;
1693 }
1694 assert(curr == mr.end(), "post-condition");
1695 }
1696 } else {
1697 // The expansion of the virtual storage space was unsuccessful.
1698 // Let's see if it was because we ran out of swap.
1699 if (G1ExitOnExpansionFailure &&
1700 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1701 // We had head room...
1702 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1703 }
1704 }
1705
1706 if (Verbose && PrintGC) {
1707 size_t new_mem_size = _g1_storage.committed_size();
1708 gclog_or_tty->print_cr("...%s, expanded to %ldK",
1709 (successful ? "Successful" : "Failed"),
1710 new_mem_size/K);
1711 }
1712 return successful;
1713 }
1714
1715 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1716 size_t old_mem_size = _g1_storage.committed_size();
1717 size_t aligned_shrink_bytes =
1718 ReservedSpace::page_align_size_down(shrink_bytes);
1719 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1720 HeapRegion::GrainBytes);
1721 size_t num_regions_deleted = 0;
1722 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1723 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1724 assert(mr.end() == old_end, "post-condition");
1725 if (mr.byte_size() > 0) {
1726 if (_hr_printer.is_active()) {
1727 HeapWord* curr = mr.end();
1728 while (curr > mr.start()) {
1729 HeapWord* curr_end = curr;
1730 curr -= HeapRegion::GrainWords;
1731 _hr_printer.uncommit(curr, curr_end);
1732 }
1733 assert(curr == mr.start(), "post-condition");
1734 }
1735
1736 _g1_storage.shrink_by(mr.byte_size());
1737 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1738 assert(mr.start() == new_end, "post-condition");
1739
1740 _expansion_regions += num_regions_deleted;
1741 update_committed_space(old_end, new_end);
1742 HeapRegionRemSet::shrink_heap(n_regions());
1743
1744 if (Verbose && PrintGC) {
1745 size_t new_mem_size = _g1_storage.committed_size();
1746 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1747 old_mem_size/K, aligned_shrink_bytes/K,
1748 new_mem_size/K);
1749 }
1750 }
1751 }
1752
1753 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1754 verify_region_sets_optional();
1755
1756 // We should only reach here at the end of a Full GC which means we
1757 // should not not be holding to any GC alloc regions. The method
1758 // below will make sure of that and do any remaining clean up.
1759 abandon_gc_alloc_regions();
1760
1761 // Instead of tearing down / rebuilding the free lists here, we
1762 // could instead use the remove_all_pending() method on free_list to
1763 // remove only the ones that we need to remove.
1764 tear_down_region_lists(); // We will rebuild them in a moment.
1765 shrink_helper(shrink_bytes);
1766 rebuild_region_lists();
1767
1768 _hrs.verify_optional();
1769 verify_region_sets_optional();
1770 }
1771
1772 // Public methods.
1773
1774 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1775 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1776 #endif // _MSC_VER
1777
1778
1779 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1780 SharedHeap(policy_),
1781 _g1_policy(policy_),
1782 _dirty_card_queue_set(false),
1783 _into_cset_dirty_card_queue_set(false),
1784 _is_alive_closure(this),
1785 _ref_processor(NULL),
1786 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1787 _bot_shared(NULL),
1788 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1789 _evac_failure_scan_stack(NULL) ,
1790 _mark_in_progress(false),
1791 _cg1r(NULL), _summary_bytes_used(0),
1792 _refine_cte_cl(NULL),
1793 _full_collection(false),
1794 _free_list("Master Free List"),
1795 _secondary_free_list("Secondary Free List"),
1796 _humongous_set("Master Humongous Set"),
1797 _free_regions_coming(false),
1798 _young_list(new YoungList(this)),
1799 _gc_time_stamp(0),
1800 _retained_old_gc_alloc_region(NULL),
1801 _surviving_young_words(NULL),
1802 _full_collections_completed(0),
1803 _in_cset_fast_test(NULL),
1804 _in_cset_fast_test_base(NULL),
1805 _dirty_cards_region_list(NULL) {
1806 _g1h = this; // To catch bugs.
1807 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1808 vm_exit_during_initialization("Failed necessary allocation.");
1809 }
1810
1811 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1812
1813 int n_queues = MAX2((int)ParallelGCThreads, 1);
1814 _task_queues = new RefToScanQueueSet(n_queues);
1815
1816 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1817 assert(n_rem_sets > 0, "Invariant.");
1818
1819 HeapRegionRemSetIterator** iter_arr =
1820 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1821 for (int i = 0; i < n_queues; i++) {
1822 iter_arr[i] = new HeapRegionRemSetIterator();
1823 }
1824 _rem_set_iterator = iter_arr;
1825
1826 for (int i = 0; i < n_queues; i++) {
1827 RefToScanQueue* q = new RefToScanQueue();
1828 q->initialize();
1829 _task_queues->register_queue(i, q);
1830 }
1831
1832 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1833 }
1834
1835 jint G1CollectedHeap::initialize() {
1836 CollectedHeap::pre_initialize();
1837 os::enable_vtime();
1838
1839 // Necessary to satisfy locking discipline assertions.
1840
1841 MutexLocker x(Heap_lock);
1842
1843 // We have to initialize the printer before committing the heap, as
1844 // it will be used then.
1845 _hr_printer.set_active(G1PrintHeapRegions);
1846
1847 // While there are no constraints in the GC code that HeapWordSize
1848 // be any particular value, there are multiple other areas in the
1849 // system which believe this to be true (e.g. oop->object_size in some
1850 // cases incorrectly returns the size in wordSize units rather than
1851 // HeapWordSize).
1852 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1853
1854 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1855 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1856
1857 // Ensure that the sizes are properly aligned.
1858 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1859 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1860
1861 _cg1r = new ConcurrentG1Refine();
1862
1863 // Reserve the maximum.
1864 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1865 // Includes the perm-gen.
1866
1867 // When compressed oops are enabled, the preferred heap base
1868 // is calculated by subtracting the requested size from the
1869 // 32Gb boundary and using the result as the base address for
1870 // heap reservation. If the requested size is not aligned to
1871 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1872 // into the ReservedHeapSpace constructor) then the actual
1873 // base of the reserved heap may end up differing from the
1874 // address that was requested (i.e. the preferred heap base).
1875 // If this happens then we could end up using a non-optimal
1876 // compressed oops mode.
1877
1878 // Since max_byte_size is aligned to the size of a heap region (checked
1879 // above), we also need to align the perm gen size as it might not be.
1880 const size_t total_reserved = max_byte_size +
1881 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1882 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1883
1884 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1885
1886 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1887 UseLargePages, addr);
1888
1889 if (UseCompressedOops) {
1890 if (addr != NULL && !heap_rs.is_reserved()) {
1891 // Failed to reserve at specified address - the requested memory
1892 // region is taken already, for example, by 'java' launcher.
1893 // Try again to reserver heap higher.
1894 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1895
1896 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1897 UseLargePages, addr);
1898
1899 if (addr != NULL && !heap_rs0.is_reserved()) {
1900 // Failed to reserve at specified address again - give up.
1901 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1902 assert(addr == NULL, "");
1903
1904 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1905 UseLargePages, addr);
1906 heap_rs = heap_rs1;
1907 } else {
1908 heap_rs = heap_rs0;
1909 }
1910 }
1911 }
1912
1913 if (!heap_rs.is_reserved()) {
1914 vm_exit_during_initialization("Could not reserve enough space for object heap");
1915 return JNI_ENOMEM;
1916 }
1917
1918 // It is important to do this in a way such that concurrent readers can't
1919 // temporarily think somethings in the heap. (I've actually seen this
1920 // happen in asserts: DLD.)
1921 _reserved.set_word_size(0);
1922 _reserved.set_start((HeapWord*)heap_rs.base());
1923 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1924
1925 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1926
1927 // Create the gen rem set (and barrier set) for the entire reserved region.
1928 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1929 set_barrier_set(rem_set()->bs());
1930 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1931 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1932 } else {
1933 vm_exit_during_initialization("G1 requires a mod ref bs.");
1934 return JNI_ENOMEM;
1935 }
1936
1937 // Also create a G1 rem set.
1938 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1939 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1940 } else {
1941 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1942 return JNI_ENOMEM;
1943 }
1944
1945 // Carve out the G1 part of the heap.
1946
1947 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1948 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1949 g1_rs.size()/HeapWordSize);
1950 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1951
1952 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1953
1954 _g1_storage.initialize(g1_rs, 0);
1955 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1956 _hrs.initialize((HeapWord*) _g1_reserved.start(),
1957 (HeapWord*) _g1_reserved.end(),
1958 _expansion_regions);
1959
1960 // 6843694 - ensure that the maximum region index can fit
1961 // in the remembered set structures.
1962 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1963 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1964
1965 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1966 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1967 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1968 "too many cards per region");
1969
1970 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
1971
1972 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1973 heap_word_size(init_byte_size));
1974
1975 _g1h = this;
1976
1977 _in_cset_fast_test_length = max_regions();
1978 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
1979
1980 // We're biasing _in_cset_fast_test to avoid subtracting the
1981 // beginning of the heap every time we want to index; basically
1982 // it's the same with what we do with the card table.
1983 _in_cset_fast_test = _in_cset_fast_test_base -
1984 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
1985
1986 // Clear the _cset_fast_test bitmap in anticipation of adding
1987 // regions to the incremental collection set for the first
1988 // evacuation pause.
1989 clear_cset_fast_test();
1990
1991 // Create the ConcurrentMark data structure and thread.
1992 // (Must do this late, so that "max_regions" is defined.)
1993 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1994 _cmThread = _cm->cmThread();
1995
1996 // Initialize the from_card cache structure of HeapRegionRemSet.
1997 HeapRegionRemSet::init_heap(max_regions());
1998
1999 // Now expand into the initial heap size.
2000 if (!expand(init_byte_size)) {
2001 vm_exit_during_initialization("Failed to allocate initial heap.");
2002 return JNI_ENOMEM;
2003 }
2004
2005 // Perform any initialization actions delegated to the policy.
2006 g1_policy()->init();
2007
2008 g1_policy()->note_start_of_mark_thread();
2009
2010 _refine_cte_cl =
2011 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2012 g1_rem_set(),
2013 concurrent_g1_refine());
2014 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2015
2016 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2017 SATB_Q_FL_lock,
2018 G1SATBProcessCompletedThreshold,
2019 Shared_SATB_Q_lock);
2020
2021 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2022 DirtyCardQ_FL_lock,
2023 concurrent_g1_refine()->yellow_zone(),
2024 concurrent_g1_refine()->red_zone(),
2025 Shared_DirtyCardQ_lock);
2026
2027 if (G1DeferredRSUpdate) {
2028 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2029 DirtyCardQ_FL_lock,
2030 -1, // never trigger processing
2031 -1, // no limit on length
2032 Shared_DirtyCardQ_lock,
2033 &JavaThread::dirty_card_queue_set());
2034 }
2035
2036 // Initialize the card queue set used to hold cards containing
2037 // references into the collection set.
2038 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2039 DirtyCardQ_FL_lock,
2040 -1, // never trigger processing
2041 -1, // no limit on length
2042 Shared_DirtyCardQ_lock,
2043 &JavaThread::dirty_card_queue_set());
2044
2045 // In case we're keeping closure specialization stats, initialize those
2046 // counts and that mechanism.
2047 SpecializationStats::clear();
2048
2049 // Do later initialization work for concurrent refinement.
2050 _cg1r->init();
2051
2052 // Here we allocate the dummy full region that is required by the
2053 // G1AllocRegion class. If we don't pass an address in the reserved
2054 // space here, lots of asserts fire.
2055
2056 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2057 _g1_reserved.start());
2058 // We'll re-use the same region whether the alloc region will
2059 // require BOT updates or not and, if it doesn't, then a non-young
2060 // region will complain that it cannot support allocations without
2061 // BOT updates. So we'll tag the dummy region as young to avoid that.
2062 dummy_region->set_young();
2063 // Make sure it's full.
2064 dummy_region->set_top(dummy_region->end());
2065 G1AllocRegion::setup(this, dummy_region);
2066
2067 init_mutator_alloc_region();
2068
2069 // Do create of the monitoring and management support so that
2070 // values in the heap have been properly initialized.
2071 _g1mm = new G1MonitoringSupport(this, &_g1_storage);
2072
2073 return JNI_OK;
2074 }
2075
2076 void G1CollectedHeap::ref_processing_init() {
2077 // Reference processing in G1 currently works as follows:
2078 //
2079 // * There is only one reference processor instance that
2080 // 'spans' the entire heap. It is created by the code
2081 // below.
2082 // * Reference discovery is not enabled during an incremental
2083 // pause (see 6484982).
2084 // * Discoverered refs are not enqueued nor are they processed
2085 // during an incremental pause (see 6484982).
2086 // * Reference discovery is enabled at initial marking.
2087 // * Reference discovery is disabled and the discovered
2088 // references processed etc during remarking.
2089 // * Reference discovery is MT (see below).
2090 // * Reference discovery requires a barrier (see below).
2091 // * Reference processing is currently not MT (see 6608385).
2092 // * A full GC enables (non-MT) reference discovery and
2093 // processes any discovered references.
2094
2095 SharedHeap::ref_processing_init();
2096 MemRegion mr = reserved_region();
2097 _ref_processor =
2098 new ReferenceProcessor(mr, // span
2099 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
2100 (int) ParallelGCThreads, // degree of mt processing
2101 ParallelGCThreads > 1 || ConcGCThreads > 1, // mt discovery
2102 (int) MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
2103 false, // Reference discovery is not atomic
2104 &_is_alive_closure, // is alive closure for efficiency
2105 true); // Setting next fields of discovered
2106 // lists requires a barrier.
2107 }
2108
2109 size_t G1CollectedHeap::capacity() const {
2110 return _g1_committed.byte_size();
2111 }
2112
2113 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2114 DirtyCardQueue* into_cset_dcq,
2115 bool concurrent,
2116 int worker_i) {
2117 // Clean cards in the hot card cache
2118 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2119
2120 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2121 int n_completed_buffers = 0;
2122 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2123 n_completed_buffers++;
2124 }
2125 g1_policy()->record_update_rs_processed_buffers(worker_i,
2126 (double) n_completed_buffers);
2127 dcqs.clear_n_completed_buffers();
2128 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2129 }
2130
2131
2132 // Computes the sum of the storage used by the various regions.
2133
2134 size_t G1CollectedHeap::used() const {
2135 assert(Heap_lock->owner() != NULL,
2136 "Should be owned on this thread's behalf.");
2137 size_t result = _summary_bytes_used;
2138 // Read only once in case it is set to NULL concurrently
2139 HeapRegion* hr = _mutator_alloc_region.get();
2140 if (hr != NULL)
2141 result += hr->used();
2142 return result;
2143 }
2144
2145 size_t G1CollectedHeap::used_unlocked() const {
2146 size_t result = _summary_bytes_used;
2147 return result;
2148 }
2149
2150 class SumUsedClosure: public HeapRegionClosure {
2151 size_t _used;
2152 public:
2153 SumUsedClosure() : _used(0) {}
2154 bool doHeapRegion(HeapRegion* r) {
2155 if (!r->continuesHumongous()) {
2156 _used += r->used();
2157 }
2158 return false;
2159 }
2160 size_t result() { return _used; }
2161 };
2162
2163 size_t G1CollectedHeap::recalculate_used() const {
2164 SumUsedClosure blk;
2165 heap_region_iterate(&blk);
2166 return blk.result();
2167 }
2168
2169 size_t G1CollectedHeap::unsafe_max_alloc() {
2170 if (free_regions() > 0) return HeapRegion::GrainBytes;
2171 // otherwise, is there space in the current allocation region?
2172
2173 // We need to store the current allocation region in a local variable
2174 // here. The problem is that this method doesn't take any locks and
2175 // there may be other threads which overwrite the current allocation
2176 // region field. attempt_allocation(), for example, sets it to NULL
2177 // and this can happen *after* the NULL check here but before the call
2178 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2179 // to be a problem in the optimized build, since the two loads of the
2180 // current allocation region field are optimized away.
2181 HeapRegion* hr = _mutator_alloc_region.get();
2182 if (hr == NULL) {
2183 return 0;
2184 }
2185 return hr->free();
2186 }
2187
2188 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2189 return
2190 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2191 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2192 }
2193
2194 #ifndef PRODUCT
2195 void G1CollectedHeap::allocate_dummy_regions() {
2196 // Let's fill up most of the region
2197 size_t word_size = HeapRegion::GrainWords - 1024;
2198 // And as a result the region we'll allocate will be humongous.
2199 guarantee(isHumongous(word_size), "sanity");
2200
2201 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2202 // Let's use the existing mechanism for the allocation
2203 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2204 if (dummy_obj != NULL) {
2205 MemRegion mr(dummy_obj, word_size);
2206 CollectedHeap::fill_with_object(mr);
2207 } else {
2208 // If we can't allocate once, we probably cannot allocate
2209 // again. Let's get out of the loop.
2210 break;
2211 }
2212 }
2213 }
2214 #endif // !PRODUCT
2215
2216 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2217 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2218
2219 // We assume that if concurrent == true, then the caller is a
2220 // concurrent thread that was joined the Suspendible Thread
2221 // Set. If there's ever a cheap way to check this, we should add an
2222 // assert here.
2223
2224 // We have already incremented _total_full_collections at the start
2225 // of the GC, so total_full_collections() represents how many full
2226 // collections have been started.
2227 unsigned int full_collections_started = total_full_collections();
2228
2229 // Given that this method is called at the end of a Full GC or of a
2230 // concurrent cycle, and those can be nested (i.e., a Full GC can
2231 // interrupt a concurrent cycle), the number of full collections
2232 // completed should be either one (in the case where there was no
2233 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2234 // behind the number of full collections started.
2235
2236 // This is the case for the inner caller, i.e. a Full GC.
2237 assert(concurrent ||
2238 (full_collections_started == _full_collections_completed + 1) ||
2239 (full_collections_started == _full_collections_completed + 2),
2240 err_msg("for inner caller (Full GC): full_collections_started = %u "
2241 "is inconsistent with _full_collections_completed = %u",
2242 full_collections_started, _full_collections_completed));
2243
2244 // This is the case for the outer caller, i.e. the concurrent cycle.
2245 assert(!concurrent ||
2246 (full_collections_started == _full_collections_completed + 1),
2247 err_msg("for outer caller (concurrent cycle): "
2248 "full_collections_started = %u "
2249 "is inconsistent with _full_collections_completed = %u",
2250 full_collections_started, _full_collections_completed));
2251
2252 _full_collections_completed += 1;
2253
2254 // We need to clear the "in_progress" flag in the CM thread before
2255 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2256 // is set) so that if a waiter requests another System.gc() it doesn't
2257 // incorrectly see that a marking cyle is still in progress.
2258 if (concurrent) {
2259 _cmThread->clear_in_progress();
2260 }
2261
2262 // This notify_all() will ensure that a thread that called
2263 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2264 // and it's waiting for a full GC to finish will be woken up. It is
2265 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2266 FullGCCount_lock->notify_all();
2267 }
2268
2269 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2270 assert_at_safepoint(true /* should_be_vm_thread */);
2271 GCCauseSetter gcs(this, cause);
2272 switch (cause) {
2273 case GCCause::_heap_inspection:
2274 case GCCause::_heap_dump: {
2275 HandleMark hm;
2276 do_full_collection(false); // don't clear all soft refs
2277 break;
2278 }
2279 default: // XXX FIX ME
2280 ShouldNotReachHere(); // Unexpected use of this function
2281 }
2282 }
2283
2284 void G1CollectedHeap::collect(GCCause::Cause cause) {
2285 // The caller doesn't have the Heap_lock
2286 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2287
2288 unsigned int gc_count_before;
2289 unsigned int full_gc_count_before;
2290 {
2291 MutexLocker ml(Heap_lock);
2292
2293 // Read the GC count while holding the Heap_lock
2294 gc_count_before = SharedHeap::heap()->total_collections();
2295 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2296 }
2297
2298 if (should_do_concurrent_full_gc(cause)) {
2299 // Schedule an initial-mark evacuation pause that will start a
2300 // concurrent cycle. We're setting word_size to 0 which means that
2301 // we are not requesting a post-GC allocation.
2302 VM_G1IncCollectionPause op(gc_count_before,
2303 0, /* word_size */
2304 true, /* should_initiate_conc_mark */
2305 g1_policy()->max_pause_time_ms(),
2306 cause);
2307 VMThread::execute(&op);
2308 } else {
2309 if (cause == GCCause::_gc_locker
2310 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2311
2312 // Schedule a standard evacuation pause. We're setting word_size
2313 // to 0 which means that we are not requesting a post-GC allocation.
2314 VM_G1IncCollectionPause op(gc_count_before,
2315 0, /* word_size */
2316 false, /* should_initiate_conc_mark */
2317 g1_policy()->max_pause_time_ms(),
2318 cause);
2319 VMThread::execute(&op);
2320 } else {
2321 // Schedule a Full GC.
2322 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2323 VMThread::execute(&op);
2324 }
2325 }
2326 }
2327
2328 bool G1CollectedHeap::is_in(const void* p) const {
2329 HeapRegion* hr = _hrs.addr_to_region((HeapWord*) p);
2330 if (hr != NULL) {
2331 return hr->is_in(p);
2332 } else {
2333 return _perm_gen->as_gen()->is_in(p);
2334 }
2335 }
2336
2337 // Iteration functions.
2338
2339 // Iterates an OopClosure over all ref-containing fields of objects
2340 // within a HeapRegion.
2341
2342 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2343 MemRegion _mr;
2344 OopClosure* _cl;
2345 public:
2346 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2347 : _mr(mr), _cl(cl) {}
2348 bool doHeapRegion(HeapRegion* r) {
2349 if (! r->continuesHumongous()) {
2350 r->oop_iterate(_cl);
2351 }
2352 return false;
2353 }
2354 };
2355
2356 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2357 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2358 heap_region_iterate(&blk);
2359 if (do_perm) {
2360 perm_gen()->oop_iterate(cl);
2361 }
2362 }
2363
2364 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2365 IterateOopClosureRegionClosure blk(mr, cl);
2366 heap_region_iterate(&blk);
2367 if (do_perm) {
2368 perm_gen()->oop_iterate(cl);
2369 }
2370 }
2371
2372 // Iterates an ObjectClosure over all objects within a HeapRegion.
2373
2374 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2375 ObjectClosure* _cl;
2376 public:
2377 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2378 bool doHeapRegion(HeapRegion* r) {
2379 if (! r->continuesHumongous()) {
2380 r->object_iterate(_cl);
2381 }
2382 return false;
2383 }
2384 };
2385
2386 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2387 IterateObjectClosureRegionClosure blk(cl);
2388 heap_region_iterate(&blk);
2389 if (do_perm) {
2390 perm_gen()->object_iterate(cl);
2391 }
2392 }
2393
2394 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2395 // FIXME: is this right?
2396 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2397 }
2398
2399 // Calls a SpaceClosure on a HeapRegion.
2400
2401 class SpaceClosureRegionClosure: public HeapRegionClosure {
2402 SpaceClosure* _cl;
2403 public:
2404 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2405 bool doHeapRegion(HeapRegion* r) {
2406 _cl->do_space(r);
2407 return false;
2408 }
2409 };
2410
2411 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2412 SpaceClosureRegionClosure blk(cl);
2413 heap_region_iterate(&blk);
2414 }
2415
2416 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2417 _hrs.iterate(cl);
2418 }
2419
2420 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2421 HeapRegionClosure* cl) const {
2422 _hrs.iterate_from(r, cl);
2423 }
2424
2425 void
2426 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2427 int worker,
2428 jint claim_value) {
2429 const size_t regions = n_regions();
2430 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
2431 // try to spread out the starting points of the workers
2432 const size_t start_index = regions / worker_num * (size_t) worker;
2433
2434 // each worker will actually look at all regions
2435 for (size_t count = 0; count < regions; ++count) {
2436 const size_t index = (start_index + count) % regions;
2437 assert(0 <= index && index < regions, "sanity");
2438 HeapRegion* r = region_at(index);
2439 // we'll ignore "continues humongous" regions (we'll process them
2440 // when we come across their corresponding "start humongous"
2441 // region) and regions already claimed
2442 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2443 continue;
2444 }
2445 // OK, try to claim it
2446 if (r->claimHeapRegion(claim_value)) {
2447 // success!
2448 assert(!r->continuesHumongous(), "sanity");
2449 if (r->startsHumongous()) {
2450 // If the region is "starts humongous" we'll iterate over its
2451 // "continues humongous" first; in fact we'll do them
2452 // first. The order is important. In on case, calling the
2453 // closure on the "starts humongous" region might de-allocate
2454 // and clear all its "continues humongous" regions and, as a
2455 // result, we might end up processing them twice. So, we'll do
2456 // them first (notice: most closures will ignore them anyway) and
2457 // then we'll do the "starts humongous" region.
2458 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2459 HeapRegion* chr = region_at(ch_index);
2460
2461 // if the region has already been claimed or it's not
2462 // "continues humongous" we're done
2463 if (chr->claim_value() == claim_value ||
2464 !chr->continuesHumongous()) {
2465 break;
2466 }
2467
2468 // Noone should have claimed it directly. We can given
2469 // that we claimed its "starts humongous" region.
2470 assert(chr->claim_value() != claim_value, "sanity");
2471 assert(chr->humongous_start_region() == r, "sanity");
2472
2473 if (chr->claimHeapRegion(claim_value)) {
2474 // we should always be able to claim it; noone else should
2475 // be trying to claim this region
2476
2477 bool res2 = cl->doHeapRegion(chr);
2478 assert(!res2, "Should not abort");
2479
2480 // Right now, this holds (i.e., no closure that actually
2481 // does something with "continues humongous" regions
2482 // clears them). We might have to weaken it in the future,
2483 // but let's leave these two asserts here for extra safety.
2484 assert(chr->continuesHumongous(), "should still be the case");
2485 assert(chr->humongous_start_region() == r, "sanity");
2486 } else {
2487 guarantee(false, "we should not reach here");
2488 }
2489 }
2490 }
2491
2492 assert(!r->continuesHumongous(), "sanity");
2493 bool res = cl->doHeapRegion(r);
2494 assert(!res, "Should not abort");
2495 }
2496 }
2497 }
2498
2499 class ResetClaimValuesClosure: public HeapRegionClosure {
2500 public:
2501 bool doHeapRegion(HeapRegion* r) {
2502 r->set_claim_value(HeapRegion::InitialClaimValue);
2503 return false;
2504 }
2505 };
2506
2507 void
2508 G1CollectedHeap::reset_heap_region_claim_values() {
2509 ResetClaimValuesClosure blk;
2510 heap_region_iterate(&blk);
2511 }
2512
2513 #ifdef ASSERT
2514 // This checks whether all regions in the heap have the correct claim
2515 // value. I also piggy-backed on this a check to ensure that the
2516 // humongous_start_region() information on "continues humongous"
2517 // regions is correct.
2518
2519 class CheckClaimValuesClosure : public HeapRegionClosure {
2520 private:
2521 jint _claim_value;
2522 size_t _failures;
2523 HeapRegion* _sh_region;
2524 public:
2525 CheckClaimValuesClosure(jint claim_value) :
2526 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2527 bool doHeapRegion(HeapRegion* r) {
2528 if (r->claim_value() != _claim_value) {
2529 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2530 "claim value = %d, should be %d",
2531 r->bottom(), r->end(), r->claim_value(),
2532 _claim_value);
2533 ++_failures;
2534 }
2535 if (!r->isHumongous()) {
2536 _sh_region = NULL;
2537 } else if (r->startsHumongous()) {
2538 _sh_region = r;
2539 } else if (r->continuesHumongous()) {
2540 if (r->humongous_start_region() != _sh_region) {
2541 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2542 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2543 r->bottom(), r->end(),
2544 r->humongous_start_region(),
2545 _sh_region);
2546 ++_failures;
2547 }
2548 }
2549 return false;
2550 }
2551 size_t failures() {
2552 return _failures;
2553 }
2554 };
2555
2556 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2557 CheckClaimValuesClosure cl(claim_value);
2558 heap_region_iterate(&cl);
2559 return cl.failures() == 0;
2560 }
2561 #endif // ASSERT
2562
2563 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2564 HeapRegion* r = g1_policy()->collection_set();
2565 while (r != NULL) {
2566 HeapRegion* next = r->next_in_collection_set();
2567 if (cl->doHeapRegion(r)) {
2568 cl->incomplete();
2569 return;
2570 }
2571 r = next;
2572 }
2573 }
2574
2575 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2576 HeapRegionClosure *cl) {
2577 if (r == NULL) {
2578 // The CSet is empty so there's nothing to do.
2579 return;
2580 }
2581
2582 assert(r->in_collection_set(),
2583 "Start region must be a member of the collection set.");
2584 HeapRegion* cur = r;
2585 while (cur != NULL) {
2586 HeapRegion* next = cur->next_in_collection_set();
2587 if (cl->doHeapRegion(cur) && false) {
2588 cl->incomplete();
2589 return;
2590 }
2591 cur = next;
2592 }
2593 cur = g1_policy()->collection_set();
2594 while (cur != r) {
2595 HeapRegion* next = cur->next_in_collection_set();
2596 if (cl->doHeapRegion(cur) && false) {
2597 cl->incomplete();
2598 return;
2599 }
2600 cur = next;
2601 }
2602 }
2603
2604 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2605 return n_regions() > 0 ? region_at(0) : NULL;
2606 }
2607
2608
2609 Space* G1CollectedHeap::space_containing(const void* addr) const {
2610 Space* res = heap_region_containing(addr);
2611 if (res == NULL)
2612 res = perm_gen()->space_containing(addr);
2613 return res;
2614 }
2615
2616 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2617 Space* sp = space_containing(addr);
2618 if (sp != NULL) {
2619 return sp->block_start(addr);
2620 }
2621 return NULL;
2622 }
2623
2624 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2625 Space* sp = space_containing(addr);
2626 assert(sp != NULL, "block_size of address outside of heap");
2627 return sp->block_size(addr);
2628 }
2629
2630 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2631 Space* sp = space_containing(addr);
2632 return sp->block_is_obj(addr);
2633 }
2634
2635 bool G1CollectedHeap::supports_tlab_allocation() const {
2636 return true;
2637 }
2638
2639 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2640 return HeapRegion::GrainBytes;
2641 }
2642
2643 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2644 // Return the remaining space in the cur alloc region, but not less than
2645 // the min TLAB size.
2646
2647 // Also, this value can be at most the humongous object threshold,
2648 // since we can't allow tlabs to grow big enough to accomodate
2649 // humongous objects.
2650
2651 HeapRegion* hr = _mutator_alloc_region.get();
2652 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2653 if (hr == NULL) {
2654 return max_tlab_size;
2655 } else {
2656 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2657 }
2658 }
2659
2660 size_t G1CollectedHeap::max_capacity() const {
2661 return _g1_reserved.byte_size();
2662 }
2663
2664 jlong G1CollectedHeap::millis_since_last_gc() {
2665 // assert(false, "NYI");
2666 return 0;
2667 }
2668
2669 void G1CollectedHeap::prepare_for_verify() {
2670 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2671 ensure_parsability(false);
2672 }
2673 g1_rem_set()->prepare_for_verify();
2674 }
2675
2676 class VerifyLivenessOopClosure: public OopClosure {
2677 G1CollectedHeap* _g1h;
2678 VerifyOption _vo;
2679 public:
2680 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2681 _g1h(g1h), _vo(vo)
2682 { }
2683 void do_oop(narrowOop *p) { do_oop_work(p); }
2684 void do_oop( oop *p) { do_oop_work(p); }
2685
2686 template <class T> void do_oop_work(T *p) {
2687 oop obj = oopDesc::load_decode_heap_oop(p);
2688 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2689 "Dead object referenced by a not dead object");
2690 }
2691 };
2692
2693 class VerifyObjsInRegionClosure: public ObjectClosure {
2694 private:
2695 G1CollectedHeap* _g1h;
2696 size_t _live_bytes;
2697 HeapRegion *_hr;
2698 VerifyOption _vo;
2699 public:
2700 // _vo == UsePrevMarking -> use "prev" marking information,
2701 // _vo == UseNextMarking -> use "next" marking information,
2702 // _vo == UseMarkWord -> use mark word from object header.
2703 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2704 : _live_bytes(0), _hr(hr), _vo(vo) {
2705 _g1h = G1CollectedHeap::heap();
2706 }
2707 void do_object(oop o) {
2708 VerifyLivenessOopClosure isLive(_g1h, _vo);
2709 assert(o != NULL, "Huh?");
2710 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2711 // If the object is alive according to the mark word,
2712 // then verify that the marking information agrees.
2713 // Note we can't verify the contra-positive of the
2714 // above: if the object is dead (according to the mark
2715 // word), it may not be marked, or may have been marked
2716 // but has since became dead, or may have been allocated
2717 // since the last marking.
2718 if (_vo == VerifyOption_G1UseMarkWord) {
2719 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2720 }
2721
2722 o->oop_iterate(&isLive);
2723 if (!_hr->obj_allocated_since_prev_marking(o)) {
2724 size_t obj_size = o->size(); // Make sure we don't overflow
2725 _live_bytes += (obj_size * HeapWordSize);
2726 }
2727 }
2728 }
2729 size_t live_bytes() { return _live_bytes; }
2730 };
2731
2732 class PrintObjsInRegionClosure : public ObjectClosure {
2733 HeapRegion *_hr;
2734 G1CollectedHeap *_g1;
2735 public:
2736 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2737 _g1 = G1CollectedHeap::heap();
2738 };
2739
2740 void do_object(oop o) {
2741 if (o != NULL) {
2742 HeapWord *start = (HeapWord *) o;
2743 size_t word_sz = o->size();
2744 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2745 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2746 (void*) o, word_sz,
2747 _g1->isMarkedPrev(o),
2748 _g1->isMarkedNext(o),
2749 _hr->obj_allocated_since_prev_marking(o));
2750 HeapWord *end = start + word_sz;
2751 HeapWord *cur;
2752 int *val;
2753 for (cur = start; cur < end; cur++) {
2754 val = (int *) cur;
2755 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2756 }
2757 }
2758 }
2759 };
2760
2761 class VerifyRegionClosure: public HeapRegionClosure {
2762 private:
2763 bool _allow_dirty;
2764 bool _par;
2765 VerifyOption _vo;
2766 bool _failures;
2767 public:
2768 // _vo == UsePrevMarking -> use "prev" marking information,
2769 // _vo == UseNextMarking -> use "next" marking information,
2770 // _vo == UseMarkWord -> use mark word from object header.
2771 VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
2772 : _allow_dirty(allow_dirty),
2773 _par(par),
2774 _vo(vo),
2775 _failures(false) {}
2776
2777 bool failures() {
2778 return _failures;
2779 }
2780
2781 bool doHeapRegion(HeapRegion* r) {
2782 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2783 "Should be unclaimed at verify points.");
2784 if (!r->continuesHumongous()) {
2785 bool failures = false;
2786 r->verify(_allow_dirty, _vo, &failures);
2787 if (failures) {
2788 _failures = true;
2789 } else {
2790 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2791 r->object_iterate(¬_dead_yet_cl);
2792 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2793 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2794 "max_live_bytes "SIZE_FORMAT" "
2795 "< calculated "SIZE_FORMAT,
2796 r->bottom(), r->end(),
2797 r->max_live_bytes(),
2798 not_dead_yet_cl.live_bytes());
2799 _failures = true;
2800 }
2801 }
2802 }
2803 return false; // stop the region iteration if we hit a failure
2804 }
2805 };
2806
2807 class VerifyRootsClosure: public OopsInGenClosure {
2808 private:
2809 G1CollectedHeap* _g1h;
2810 VerifyOption _vo;
2811 bool _failures;
2812 public:
2813 // _vo == UsePrevMarking -> use "prev" marking information,
2814 // _vo == UseNextMarking -> use "next" marking information,
2815 // _vo == UseMarkWord -> use mark word from object header.
2816 VerifyRootsClosure(VerifyOption vo) :
2817 _g1h(G1CollectedHeap::heap()),
2818 _vo(vo),
2819 _failures(false) { }
2820
2821 bool failures() { return _failures; }
2822
2823 template <class T> void do_oop_nv(T* p) {
2824 T heap_oop = oopDesc::load_heap_oop(p);
2825 if (!oopDesc::is_null(heap_oop)) {
2826 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2827 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2828 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2829 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2830 if (_vo == VerifyOption_G1UseMarkWord) {
2831 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2832 }
2833 obj->print_on(gclog_or_tty);
2834 _failures = true;
2835 }
2836 }
2837 }
2838
2839 void do_oop(oop* p) { do_oop_nv(p); }
2840 void do_oop(narrowOop* p) { do_oop_nv(p); }
2841 };
2842
2843 // This is the task used for parallel heap verification.
2844
2845 class G1ParVerifyTask: public AbstractGangTask {
2846 private:
2847 G1CollectedHeap* _g1h;
2848 bool _allow_dirty;
2849 VerifyOption _vo;
2850 bool _failures;
2851
2852 public:
2853 // _vo == UsePrevMarking -> use "prev" marking information,
2854 // _vo == UseNextMarking -> use "next" marking information,
2855 // _vo == UseMarkWord -> use mark word from object header.
2856 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
2857 AbstractGangTask("Parallel verify task"),
2858 _g1h(g1h),
2859 _allow_dirty(allow_dirty),
2860 _vo(vo),
2861 _failures(false) { }
2862
2863 bool failures() {
2864 return _failures;
2865 }
2866
2867 void work(int worker_i) {
2868 HandleMark hm;
2869 VerifyRegionClosure blk(_allow_dirty, true, _vo);
2870 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2871 HeapRegion::ParVerifyClaimValue);
2872 if (blk.failures()) {
2873 _failures = true;
2874 }
2875 }
2876 };
2877
2878 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2879 verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
2880 }
2881
2882 void G1CollectedHeap::verify(bool allow_dirty,
2883 bool silent,
2884 VerifyOption vo) {
2885 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2886 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
2887 VerifyRootsClosure rootsCl(vo);
2888 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2889
2890 // We apply the relevant closures to all the oops in the
2891 // system dictionary, the string table and the code cache.
2892 const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
2893
2894 process_strong_roots(true, // activate StrongRootsScope
2895 true, // we set "collecting perm gen" to true,
2896 // so we don't reset the dirty cards in the perm gen.
2897 SharedHeap::ScanningOption(so), // roots scanning options
2898 &rootsCl,
2899 &blobsCl,
2900 &rootsCl);
2901
2902 // If we're verifying after the marking phase of a Full GC then we can't
2903 // treat the perm gen as roots into the G1 heap. Some of the objects in
2904 // the perm gen may be dead and hence not marked. If one of these dead
2905 // objects is considered to be a root then we may end up with a false
2906 // "Root location <x> points to dead ob <y>" failure.
2907 if (vo != VerifyOption_G1UseMarkWord) {
2908 // Since we used "collecting_perm_gen" == true above, we will not have
2909 // checked the refs from perm into the G1-collected heap. We check those
2910 // references explicitly below. Whether the relevant cards are dirty
2911 // is checked further below in the rem set verification.
2912 if (!silent) { gclog_or_tty->print("Permgen roots "); }
2913 perm_gen()->oop_iterate(&rootsCl);
2914 }
2915 bool failures = rootsCl.failures();
2916
2917 if (vo != VerifyOption_G1UseMarkWord) {
2918 // If we're verifying during a full GC then the region sets
2919 // will have been torn down at the start of the GC. Therefore
2920 // verifying the region sets will fail. So we only verify
2921 // the region sets when not in a full GC.
2922 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
2923 verify_region_sets();
2924 }
2925
2926 if (!silent) { gclog_or_tty->print("HeapRegions "); }
2927 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2928 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2929 "sanity check");
2930
2931 G1ParVerifyTask task(this, allow_dirty, vo);
2932 int n_workers = workers()->total_workers();
2933 set_par_threads(n_workers);
2934 workers()->run_task(&task);
2935 set_par_threads(0);
2936 if (task.failures()) {
2937 failures = true;
2938 }
2939
2940 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2941 "sanity check");
2942
2943 reset_heap_region_claim_values();
2944
2945 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2946 "sanity check");
2947 } else {
2948 VerifyRegionClosure blk(allow_dirty, false, vo);
2949 heap_region_iterate(&blk);
2950 if (blk.failures()) {
2951 failures = true;
2952 }
2953 }
2954 if (!silent) gclog_or_tty->print("RemSet ");
2955 rem_set()->verify();
2956
2957 if (failures) {
2958 gclog_or_tty->print_cr("Heap:");
2959 print_on(gclog_or_tty, true /* extended */);
2960 gclog_or_tty->print_cr("");
2961 #ifndef PRODUCT
2962 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2963 concurrent_mark()->print_reachable("at-verification-failure",
2964 vo, false /* all */);
2965 }
2966 #endif
2967 gclog_or_tty->flush();
2968 }
2969 guarantee(!failures, "there should not have been any failures");
2970 } else {
2971 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2972 }
2973 }
2974
2975 class PrintRegionClosure: public HeapRegionClosure {
2976 outputStream* _st;
2977 public:
2978 PrintRegionClosure(outputStream* st) : _st(st) {}
2979 bool doHeapRegion(HeapRegion* r) {
2980 r->print_on(_st);
2981 return false;
2982 }
2983 };
2984
2985 void G1CollectedHeap::print() const { print_on(tty); }
2986
2987 void G1CollectedHeap::print_on(outputStream* st) const {
2988 print_on(st, PrintHeapAtGCExtended);
2989 }
2990
2991 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2992 st->print(" %-20s", "garbage-first heap");
2993 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2994 capacity()/K, used_unlocked()/K);
2995 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2996 _g1_storage.low_boundary(),
2997 _g1_storage.high(),
2998 _g1_storage.high_boundary());
2999 st->cr();
3000 st->print(" region size " SIZE_FORMAT "K, ",
3001 HeapRegion::GrainBytes/K);
3002 size_t young_regions = _young_list->length();
3003 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3004 young_regions, young_regions * HeapRegion::GrainBytes / K);
3005 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3006 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3007 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3008 st->cr();
3009 perm()->as_gen()->print_on(st);
3010 if (extended) {
3011 st->cr();
3012 print_on_extended(st);
3013 }
3014 }
3015
3016 void G1CollectedHeap::print_on_extended(outputStream* st) const {
3017 PrintRegionClosure blk(st);
3018 heap_region_iterate(&blk);
3019 }
3020
3021 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3022 if (G1CollectedHeap::use_parallel_gc_threads()) {
3023 workers()->print_worker_threads_on(st);
3024 }
3025 _cmThread->print_on(st);
3026 st->cr();
3027 _cm->print_worker_threads_on(st);
3028 _cg1r->print_worker_threads_on(st);
3029 st->cr();
3030 }
3031
3032 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3033 if (G1CollectedHeap::use_parallel_gc_threads()) {
3034 workers()->threads_do(tc);
3035 }
3036 tc->do_thread(_cmThread);
3037 _cg1r->threads_do(tc);
3038 }
3039
3040 void G1CollectedHeap::print_tracing_info() const {
3041 // We'll overload this to mean "trace GC pause statistics."
3042 if (TraceGen0Time || TraceGen1Time) {
3043 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3044 // to that.
3045 g1_policy()->print_tracing_info();
3046 }
3047 if (G1SummarizeRSetStats) {
3048 g1_rem_set()->print_summary_info();
3049 }
3050 if (G1SummarizeConcMark) {
3051 concurrent_mark()->print_summary_info();
3052 }
3053 g1_policy()->print_yg_surv_rate_info();
3054 SpecializationStats::print();
3055 }
3056
3057 #ifndef PRODUCT
3058 // Helpful for debugging RSet issues.
3059
3060 class PrintRSetsClosure : public HeapRegionClosure {
3061 private:
3062 const char* _msg;
3063 size_t _occupied_sum;
3064
3065 public:
3066 bool doHeapRegion(HeapRegion* r) {
3067 HeapRegionRemSet* hrrs = r->rem_set();
3068 size_t occupied = hrrs->occupied();
3069 _occupied_sum += occupied;
3070
3071 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3072 HR_FORMAT_PARAMS(r));
3073 if (occupied == 0) {
3074 gclog_or_tty->print_cr(" RSet is empty");
3075 } else {
3076 hrrs->print();
3077 }
3078 gclog_or_tty->print_cr("----------");
3079 return false;
3080 }
3081
3082 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3083 gclog_or_tty->cr();
3084 gclog_or_tty->print_cr("========================================");
3085 gclog_or_tty->print_cr(msg);
3086 gclog_or_tty->cr();
3087 }
3088
3089 ~PrintRSetsClosure() {
3090 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3091 gclog_or_tty->print_cr("========================================");
3092 gclog_or_tty->cr();
3093 }
3094 };
3095
3096 void G1CollectedHeap::print_cset_rsets() {
3097 PrintRSetsClosure cl("Printing CSet RSets");
3098 collection_set_iterate(&cl);
3099 }
3100
3101 void G1CollectedHeap::print_all_rsets() {
3102 PrintRSetsClosure cl("Printing All RSets");;
3103 heap_region_iterate(&cl);
3104 }
3105 #endif // PRODUCT
3106
3107 G1CollectedHeap* G1CollectedHeap::heap() {
3108 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3109 "not a garbage-first heap");
3110 return _g1h;
3111 }
3112
3113 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3114 // always_do_update_barrier = false;
3115 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3116 // Call allocation profiler
3117 AllocationProfiler::iterate_since_last_gc();
3118 // Fill TLAB's and such
3119 ensure_parsability(true);
3120 }
3121
3122 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3123 // FIXME: what is this about?
3124 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3125 // is set.
3126 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3127 "derived pointer present"));
3128 // always_do_update_barrier = true;
3129 }
3130
3131 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3132 unsigned int gc_count_before,
3133 bool* succeeded) {
3134 assert_heap_not_locked_and_not_at_safepoint();
3135 g1_policy()->record_stop_world_start();
3136 VM_G1IncCollectionPause op(gc_count_before,
3137 word_size,
3138 false, /* should_initiate_conc_mark */
3139 g1_policy()->max_pause_time_ms(),
3140 GCCause::_g1_inc_collection_pause);
3141 VMThread::execute(&op);
3142
3143 HeapWord* result = op.result();
3144 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3145 assert(result == NULL || ret_succeeded,
3146 "the result should be NULL if the VM did not succeed");
3147 *succeeded = ret_succeeded;
3148
3149 assert_heap_not_locked();
3150 return result;
3151 }
3152
3153 void
3154 G1CollectedHeap::doConcurrentMark() {
3155 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3156 if (!_cmThread->in_progress()) {
3157 _cmThread->set_started();
3158 CGC_lock->notify();
3159 }
3160 }
3161
3162 // <NEW PREDICTION>
3163
3164 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3165 bool young) {
3166 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3167 }
3168
3169 void G1CollectedHeap::check_if_region_is_too_expensive(double
3170 predicted_time_ms) {
3171 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3172 }
3173
3174 size_t G1CollectedHeap::pending_card_num() {
3175 size_t extra_cards = 0;
3176 JavaThread *curr = Threads::first();
3177 while (curr != NULL) {
3178 DirtyCardQueue& dcq = curr->dirty_card_queue();
3179 extra_cards += dcq.size();
3180 curr = curr->next();
3181 }
3182 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3183 size_t buffer_size = dcqs.buffer_size();
3184 size_t buffer_num = dcqs.completed_buffers_num();
3185 return buffer_size * buffer_num + extra_cards;
3186 }
3187
3188 size_t G1CollectedHeap::max_pending_card_num() {
3189 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3190 size_t buffer_size = dcqs.buffer_size();
3191 size_t buffer_num = dcqs.completed_buffers_num();
3192 int thread_num = Threads::number_of_threads();
3193 return (buffer_num + thread_num) * buffer_size;
3194 }
3195
3196 size_t G1CollectedHeap::cards_scanned() {
3197 return g1_rem_set()->cardsScanned();
3198 }
3199
3200 void
3201 G1CollectedHeap::setup_surviving_young_words() {
3202 guarantee( _surviving_young_words == NULL, "pre-condition" );
3203 size_t array_length = g1_policy()->young_cset_length();
3204 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3205 if (_surviving_young_words == NULL) {
3206 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3207 "Not enough space for young surv words summary.");
3208 }
3209 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3210 #ifdef ASSERT
3211 for (size_t i = 0; i < array_length; ++i) {
3212 assert( _surviving_young_words[i] == 0, "memset above" );
3213 }
3214 #endif // !ASSERT
3215 }
3216
3217 void
3218 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3219 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3220 size_t array_length = g1_policy()->young_cset_length();
3221 for (size_t i = 0; i < array_length; ++i)
3222 _surviving_young_words[i] += surv_young_words[i];
3223 }
3224
3225 void
3226 G1CollectedHeap::cleanup_surviving_young_words() {
3227 guarantee( _surviving_young_words != NULL, "pre-condition" );
3228 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3229 _surviving_young_words = NULL;
3230 }
3231
3232 // </NEW PREDICTION>
3233
3234 #ifdef ASSERT
3235 class VerifyCSetClosure: public HeapRegionClosure {
3236 public:
3237 bool doHeapRegion(HeapRegion* hr) {
3238 // Here we check that the CSet region's RSet is ready for parallel
3239 // iteration. The fields that we'll verify are only manipulated
3240 // when the region is part of a CSet and is collected. Afterwards,
3241 // we reset these fields when we clear the region's RSet (when the
3242 // region is freed) so they are ready when the region is
3243 // re-allocated. The only exception to this is if there's an
3244 // evacuation failure and instead of freeing the region we leave
3245 // it in the heap. In that case, we reset these fields during
3246 // evacuation failure handling.
3247 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3248
3249 // Here's a good place to add any other checks we'd like to
3250 // perform on CSet regions.
3251 return false;
3252 }
3253 };
3254 #endif // ASSERT
3255
3256 #if TASKQUEUE_STATS
3257 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3258 st->print_raw_cr("GC Task Stats");
3259 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3260 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3261 }
3262
3263 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3264 print_taskqueue_stats_hdr(st);
3265
3266 TaskQueueStats totals;
3267 const int n = workers() != NULL ? workers()->total_workers() : 1;
3268 for (int i = 0; i < n; ++i) {
3269 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3270 totals += task_queue(i)->stats;
3271 }
3272 st->print_raw("tot "); totals.print(st); st->cr();
3273
3274 DEBUG_ONLY(totals.verify());
3275 }
3276
3277 void G1CollectedHeap::reset_taskqueue_stats() {
3278 const int n = workers() != NULL ? workers()->total_workers() : 1;
3279 for (int i = 0; i < n; ++i) {
3280 task_queue(i)->stats.reset();
3281 }
3282 }
3283 #endif // TASKQUEUE_STATS
3284
3285 bool
3286 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3287 assert_at_safepoint(true /* should_be_vm_thread */);
3288 guarantee(!is_gc_active(), "collection is not reentrant");
3289
3290 if (GC_locker::check_active_before_gc()) {
3291 return false;
3292 }
3293
3294 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3295 ResourceMark rm;
3296
3297 if (PrintHeapAtGC) {
3298 Universe::print_heap_before_gc();
3299 }
3300
3301 verify_region_sets_optional();
3302 verify_dirty_young_regions();
3303
3304 {
3305 // This call will decide whether this pause is an initial-mark
3306 // pause. If it is, during_initial_mark_pause() will return true
3307 // for the duration of this pause.
3308 g1_policy()->decide_on_conc_mark_initiation();
3309
3310 char verbose_str[128];
3311 sprintf(verbose_str, "GC pause ");
3312 if (g1_policy()->full_young_gcs()) {
3313 strcat(verbose_str, "(young)");
3314 } else {
3315 strcat(verbose_str, "(partial)");
3316 }
3317 if (g1_policy()->during_initial_mark_pause()) {
3318 strcat(verbose_str, " (initial-mark)");
3319 // We are about to start a marking cycle, so we increment the
3320 // full collection counter.
3321 increment_total_full_collections();
3322 }
3323
3324 // if PrintGCDetails is on, we'll print long statistics information
3325 // in the collector policy code, so let's not print this as the output
3326 // is messy if we do.
3327 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3328 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3329 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3330
3331 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3332 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3333
3334 // If the secondary_free_list is not empty, append it to the
3335 // free_list. No need to wait for the cleanup operation to finish;
3336 // the region allocation code will check the secondary_free_list
3337 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3338 // set, skip this step so that the region allocation code has to
3339 // get entries from the secondary_free_list.
3340 if (!G1StressConcRegionFreeing) {
3341 append_secondary_free_list_if_not_empty_with_lock();
3342 }
3343
3344 assert(check_young_list_well_formed(),
3345 "young list should be well formed");
3346
3347 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3348 IsGCActiveMark x;
3349
3350 gc_prologue(false);
3351 increment_total_collections(false /* full gc */);
3352 increment_gc_time_stamp();
3353
3354 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3355 HandleMark hm; // Discard invalid handles created during verification
3356 gclog_or_tty->print(" VerifyBeforeGC:");
3357 prepare_for_verify();
3358 Universe::verify(/* allow dirty */ false,
3359 /* silent */ false,
3360 /* option */ VerifyOption_G1UsePrevMarking);
3361
3362 }
3363
3364 COMPILER2_PRESENT(DerivedPointerTable::clear());
3365
3366 // Please see comment in G1CollectedHeap::ref_processing_init()
3367 // to see how reference processing currently works in G1.
3368 //
3369 // We want to turn off ref discovery, if necessary, and turn it back on
3370 // on again later if we do. XXX Dubious: why is discovery disabled?
3371 bool was_enabled = ref_processor()->discovery_enabled();
3372 if (was_enabled) ref_processor()->disable_discovery();
3373
3374 // Forget the current alloc region (we might even choose it to be part
3375 // of the collection set!).
3376 release_mutator_alloc_region();
3377
3378 // We should call this after we retire the mutator alloc
3379 // region(s) so that all the ALLOC / RETIRE events are generated
3380 // before the start GC event.
3381 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3382
3383 // The elapsed time induced by the start time below deliberately elides
3384 // the possible verification above.
3385 double start_time_sec = os::elapsedTime();
3386 size_t start_used_bytes = used();
3387
3388 #if YOUNG_LIST_VERBOSE
3389 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3390 _young_list->print();
3391 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3392 #endif // YOUNG_LIST_VERBOSE
3393
3394 g1_policy()->record_collection_pause_start(start_time_sec,
3395 start_used_bytes);
3396
3397 #if YOUNG_LIST_VERBOSE
3398 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3399 _young_list->print();
3400 #endif // YOUNG_LIST_VERBOSE
3401
3402 if (g1_policy()->during_initial_mark_pause()) {
3403 concurrent_mark()->checkpointRootsInitialPre();
3404 }
3405 perm_gen()->save_marks();
3406
3407 // We must do this before any possible evacuation that should propagate
3408 // marks.
3409 if (mark_in_progress()) {
3410 double start_time_sec = os::elapsedTime();
3411
3412 _cm->drainAllSATBBuffers();
3413 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3414 g1_policy()->record_satb_drain_time(finish_mark_ms);
3415 }
3416 // Record the number of elements currently on the mark stack, so we
3417 // only iterate over these. (Since evacuation may add to the mark
3418 // stack, doing more exposes race conditions.) If no mark is in
3419 // progress, this will be zero.
3420 _cm->set_oops_do_bound();
3421
3422 if (mark_in_progress()) {
3423 concurrent_mark()->newCSet();
3424 }
3425
3426 #if YOUNG_LIST_VERBOSE
3427 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3428 _young_list->print();
3429 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3430 #endif // YOUNG_LIST_VERBOSE
3431
3432 g1_policy()->choose_collection_set(target_pause_time_ms);
3433
3434 if (_hr_printer.is_active()) {
3435 HeapRegion* hr = g1_policy()->collection_set();
3436 while (hr != NULL) {
3437 G1HRPrinter::RegionType type;
3438 if (!hr->is_young()) {
3439 type = G1HRPrinter::Old;
3440 } else if (hr->is_survivor()) {
3441 type = G1HRPrinter::Survivor;
3442 } else {
3443 type = G1HRPrinter::Eden;
3444 }
3445 _hr_printer.cset(hr);
3446 hr = hr->next_in_collection_set();
3447 }
3448 }
3449
3450 // We have chosen the complete collection set. If marking is
3451 // active then, we clear the region fields of any of the
3452 // concurrent marking tasks whose region fields point into
3453 // the collection set as these values will become stale. This
3454 // will cause the owning marking threads to claim a new region
3455 // when marking restarts.
3456 if (mark_in_progress()) {
3457 concurrent_mark()->reset_active_task_region_fields_in_cset();
3458 }
3459
3460 #ifdef ASSERT
3461 VerifyCSetClosure cl;
3462 collection_set_iterate(&cl);
3463 #endif // ASSERT
3464
3465 setup_surviving_young_words();
3466
3467 // Initialize the GC alloc regions.
3468 init_gc_alloc_regions();
3469
3470 // Actually do the work...
3471 evacuate_collection_set();
3472
3473 free_collection_set(g1_policy()->collection_set());
3474 g1_policy()->clear_collection_set();
3475
3476 cleanup_surviving_young_words();
3477
3478 // Start a new incremental collection set for the next pause.
3479 g1_policy()->start_incremental_cset_building();
3480
3481 // Clear the _cset_fast_test bitmap in anticipation of adding
3482 // regions to the incremental collection set for the next
3483 // evacuation pause.
3484 clear_cset_fast_test();
3485
3486 _young_list->reset_sampled_info();
3487
3488 // Don't check the whole heap at this point as the
3489 // GC alloc regions from this pause have been tagged
3490 // as survivors and moved on to the survivor list.
3491 // Survivor regions will fail the !is_young() check.
3492 assert(check_young_list_empty(false /* check_heap */),
3493 "young list should be empty");
3494
3495 #if YOUNG_LIST_VERBOSE
3496 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3497 _young_list->print();
3498 #endif // YOUNG_LIST_VERBOSE
3499
3500 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3501 _young_list->first_survivor_region(),
3502 _young_list->last_survivor_region());
3503
3504 _young_list->reset_auxilary_lists();
3505
3506 if (evacuation_failed()) {
3507 _summary_bytes_used = recalculate_used();
3508 } else {
3509 // The "used" of the the collection set have already been subtracted
3510 // when they were freed. Add in the bytes evacuated.
3511 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3512 }
3513
3514 if (g1_policy()->during_initial_mark_pause()) {
3515 concurrent_mark()->checkpointRootsInitialPost();
3516 set_marking_started();
3517 // CAUTION: after the doConcurrentMark() call below,
3518 // the concurrent marking thread(s) could be running
3519 // concurrently with us. Make sure that anything after
3520 // this point does not assume that we are the only GC thread
3521 // running. Note: of course, the actual marking work will
3522 // not start until the safepoint itself is released in
3523 // ConcurrentGCThread::safepoint_desynchronize().
3524 doConcurrentMark();
3525 }
3526
3527 allocate_dummy_regions();
3528
3529 #if YOUNG_LIST_VERBOSE
3530 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3531 _young_list->print();
3532 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3533 #endif // YOUNG_LIST_VERBOSE
3534
3535 init_mutator_alloc_region();
3536
3537 double end_time_sec = os::elapsedTime();
3538 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3539 g1_policy()->record_pause_time_ms(pause_time_ms);
3540 g1_policy()->record_collection_pause_end();
3541
3542 MemoryService::track_memory_usage();
3543
3544 // In prepare_for_verify() below we'll need to scan the deferred
3545 // update buffers to bring the RSets up-to-date if
3546 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3547 // the update buffers we'll probably need to scan cards on the
3548 // regions we just allocated to (i.e., the GC alloc
3549 // regions). However, during the last GC we called
3550 // set_saved_mark() on all the GC alloc regions, so card
3551 // scanning might skip the [saved_mark_word()...top()] area of
3552 // those regions (i.e., the area we allocated objects into
3553 // during the last GC). But it shouldn't. Given that
3554 // saved_mark_word() is conditional on whether the GC time stamp
3555 // on the region is current or not, by incrementing the GC time
3556 // stamp here we invalidate all the GC time stamps on all the
3557 // regions and saved_mark_word() will simply return top() for
3558 // all the regions. This is a nicer way of ensuring this rather
3559 // than iterating over the regions and fixing them. In fact, the
3560 // GC time stamp increment here also ensures that
3561 // saved_mark_word() will return top() between pauses, i.e.,
3562 // during concurrent refinement. So we don't need the
3563 // is_gc_active() check to decided which top to use when
3564 // scanning cards (see CR 7039627).
3565 increment_gc_time_stamp();
3566
3567 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3568 HandleMark hm; // Discard invalid handles created during verification
3569 gclog_or_tty->print(" VerifyAfterGC:");
3570 prepare_for_verify();
3571 Universe::verify(/* allow dirty */ true,
3572 /* silent */ false,
3573 /* option */ VerifyOption_G1UsePrevMarking);
3574 }
3575
3576 if (was_enabled) ref_processor()->enable_discovery();
3577
3578 {
3579 size_t expand_bytes = g1_policy()->expansion_amount();
3580 if (expand_bytes > 0) {
3581 size_t bytes_before = capacity();
3582 if (!expand(expand_bytes)) {
3583 // We failed to expand the heap so let's verify that
3584 // committed/uncommitted amount match the backing store
3585 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3586 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3587 }
3588 }
3589 }
3590
3591 // We should do this after we potentially expand the heap so
3592 // that all the COMMIT events are generated before the end GC
3593 // event, and after we retire the GC alloc regions so that all
3594 // RETIRE events are generated before the end GC event.
3595 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3596
3597 // We have to do this after we decide whether to expand the heap or not.
3598 g1_policy()->print_heap_transition();
3599
3600 if (mark_in_progress()) {
3601 concurrent_mark()->update_g1_committed();
3602 }
3603
3604 #ifdef TRACESPINNING
3605 ParallelTaskTerminator::print_termination_counts();
3606 #endif
3607
3608 gc_epilogue(false);
3609 }
3610
3611 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3612 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3613 print_tracing_info();
3614 vm_exit(-1);
3615 }
3616 }
3617
3618 _hrs.verify_optional();
3619 verify_region_sets_optional();
3620
3621 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3622 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3623
3624 if (PrintHeapAtGC) {
3625 Universe::print_heap_after_gc();
3626 }
3627 g1mm()->update_counters();
3628
3629 if (G1SummarizeRSetStats &&
3630 (G1SummarizeRSetStatsPeriod > 0) &&
3631 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3632 g1_rem_set()->print_summary_info();
3633 }
3634
3635 return true;
3636 }
3637
3638 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3639 {
3640 size_t gclab_word_size;
3641 switch (purpose) {
3642 case GCAllocForSurvived:
3643 gclab_word_size = YoungPLABSize;
3644 break;
3645 case GCAllocForTenured:
3646 gclab_word_size = OldPLABSize;
3647 break;
3648 default:
3649 assert(false, "unknown GCAllocPurpose");
3650 gclab_word_size = OldPLABSize;
3651 break;
3652 }
3653 return gclab_word_size;
3654 }
3655
3656 void G1CollectedHeap::init_mutator_alloc_region() {
3657 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3658 _mutator_alloc_region.init();
3659 }
3660
3661 void G1CollectedHeap::release_mutator_alloc_region() {
3662 _mutator_alloc_region.release();
3663 assert(_mutator_alloc_region.get() == NULL, "post-condition");
3664 }
3665
3666 void G1CollectedHeap::init_gc_alloc_regions() {
3667 assert_at_safepoint(true /* should_be_vm_thread */);
3668
3669 _survivor_gc_alloc_region.init();
3670 _old_gc_alloc_region.init();
3671 HeapRegion* retained_region = _retained_old_gc_alloc_region;
3672 _retained_old_gc_alloc_region = NULL;
3673
3674 // We will discard the current GC alloc region if:
3675 // a) it's in the collection set (it can happen!),
3676 // b) it's already full (no point in using it),
3677 // c) it's empty (this means that it was emptied during
3678 // a cleanup and it should be on the free list now), or
3679 // d) it's humongous (this means that it was emptied
3680 // during a cleanup and was added to the free list, but
3681 // has been subseqently used to allocate a humongous
3682 // object that may be less than the region size).
3683 if (retained_region != NULL &&
3684 !retained_region->in_collection_set() &&
3685 !(retained_region->top() == retained_region->end()) &&
3686 !retained_region->is_empty() &&
3687 !retained_region->isHumongous()) {
3688 retained_region->set_saved_mark();
3689 _old_gc_alloc_region.set(retained_region);
3690 _hr_printer.reuse(retained_region);
3691 }
3692 }
3693
3694 void G1CollectedHeap::release_gc_alloc_regions() {
3695 _survivor_gc_alloc_region.release();
3696 // If we have an old GC alloc region to release, we'll save it in
3697 // _retained_old_gc_alloc_region. If we don't
3698 // _retained_old_gc_alloc_region will become NULL. This is what we
3699 // want either way so no reason to check explicitly for either
3700 // condition.
3701 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
3702 }
3703
3704 void G1CollectedHeap::abandon_gc_alloc_regions() {
3705 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
3706 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
3707 _retained_old_gc_alloc_region = NULL;
3708 }
3709
3710 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3711 _drain_in_progress = false;
3712 set_evac_failure_closure(cl);
3713 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3714 }
3715
3716 void G1CollectedHeap::finalize_for_evac_failure() {
3717 assert(_evac_failure_scan_stack != NULL &&
3718 _evac_failure_scan_stack->length() == 0,
3719 "Postcondition");
3720 assert(!_drain_in_progress, "Postcondition");
3721 delete _evac_failure_scan_stack;
3722 _evac_failure_scan_stack = NULL;
3723 }
3724
3725 // *** Sequential G1 Evacuation
3726
3727 class G1IsAliveClosure: public BoolObjectClosure {
3728 G1CollectedHeap* _g1;
3729 public:
3730 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3731 void do_object(oop p) { assert(false, "Do not call."); }
3732 bool do_object_b(oop p) {
3733 // It is reachable if it is outside the collection set, or is inside
3734 // and forwarded.
3735
3736 #ifdef G1_DEBUG
3737 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3738 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3739 !_g1->obj_in_cs(p) || p->is_forwarded());
3740 #endif // G1_DEBUG
3741
3742 return !_g1->obj_in_cs(p) || p->is_forwarded();
3743 }
3744 };
3745
3746 class G1KeepAliveClosure: public OopClosure {
3747 G1CollectedHeap* _g1;
3748 public:
3749 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3750 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3751 void do_oop( oop* p) {
3752 oop obj = *p;
3753 #ifdef G1_DEBUG
3754 if (PrintGC && Verbose) {
3755 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3756 p, (void*) obj, (void*) *p);
3757 }
3758 #endif // G1_DEBUG
3759
3760 if (_g1->obj_in_cs(obj)) {
3761 assert( obj->is_forwarded(), "invariant" );
3762 *p = obj->forwardee();
3763 #ifdef G1_DEBUG
3764 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3765 (void*) obj, (void*) *p);
3766 #endif // G1_DEBUG
3767 }
3768 }
3769 };
3770
3771 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3772 private:
3773 G1CollectedHeap* _g1;
3774 DirtyCardQueue *_dcq;
3775 CardTableModRefBS* _ct_bs;
3776
3777 public:
3778 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3779 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3780
3781 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3782 virtual void do_oop( oop* p) { do_oop_work(p); }
3783 template <class T> void do_oop_work(T* p) {
3784 assert(_from->is_in_reserved(p), "paranoia");
3785 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3786 !_from->is_survivor()) {
3787 size_t card_index = _ct_bs->index_for(p);
3788 if (_ct_bs->mark_card_deferred(card_index)) {
3789 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3790 }
3791 }
3792 }
3793 };
3794
3795 class RemoveSelfPointerClosure: public ObjectClosure {
3796 private:
3797 G1CollectedHeap* _g1;
3798 ConcurrentMark* _cm;
3799 HeapRegion* _hr;
3800 size_t _prev_marked_bytes;
3801 size_t _next_marked_bytes;
3802 OopsInHeapRegionClosure *_cl;
3803 public:
3804 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
3805 OopsInHeapRegionClosure* cl) :
3806 _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3807 _next_marked_bytes(0), _cl(cl) {}
3808
3809 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3810 size_t next_marked_bytes() { return _next_marked_bytes; }
3811
3812 // <original comment>
3813 // The original idea here was to coalesce evacuated and dead objects.
3814 // However that caused complications with the block offset table (BOT).
3815 // In particular if there were two TLABs, one of them partially refined.
3816 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3817 // The BOT entries of the unrefined part of TLAB_2 point to the start
3818 // of TLAB_2. If the last object of the TLAB_1 and the first object
3819 // of TLAB_2 are coalesced, then the cards of the unrefined part
3820 // would point into middle of the filler object.
3821 // The current approach is to not coalesce and leave the BOT contents intact.
3822 // </original comment>
3823 //
3824 // We now reset the BOT when we start the object iteration over the
3825 // region and refine its entries for every object we come across. So
3826 // the above comment is not really relevant and we should be able
3827 // to coalesce dead objects if we want to.
3828 void do_object(oop obj) {
3829 HeapWord* obj_addr = (HeapWord*) obj;
3830 assert(_hr->is_in(obj_addr), "sanity");
3831 size_t obj_size = obj->size();
3832 _hr->update_bot_for_object(obj_addr, obj_size);
3833 if (obj->is_forwarded() && obj->forwardee() == obj) {
3834 // The object failed to move.
3835 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3836 _cm->markPrev(obj);
3837 assert(_cm->isPrevMarked(obj), "Should be marked!");
3838 _prev_marked_bytes += (obj_size * HeapWordSize);
3839 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3840 _cm->markAndGrayObjectIfNecessary(obj);
3841 }
3842 obj->set_mark(markOopDesc::prototype());
3843 // While we were processing RSet buffers during the
3844 // collection, we actually didn't scan any cards on the
3845 // collection set, since we didn't want to update remebered
3846 // sets with entries that point into the collection set, given
3847 // that live objects fromthe collection set are about to move
3848 // and such entries will be stale very soon. This change also
3849 // dealt with a reliability issue which involved scanning a
3850 // card in the collection set and coming across an array that
3851 // was being chunked and looking malformed. The problem is
3852 // that, if evacuation fails, we might have remembered set
3853 // entries missing given that we skipped cards on the
3854 // collection set. So, we'll recreate such entries now.
3855 obj->oop_iterate(_cl);
3856 assert(_cm->isPrevMarked(obj), "Should be marked!");
3857 } else {
3858 // The object has been either evacuated or is dead. Fill it with a
3859 // dummy object.
3860 MemRegion mr((HeapWord*)obj, obj_size);
3861 CollectedHeap::fill_with_object(mr);
3862 _cm->clearRangeBothMaps(mr);
3863 }
3864 }
3865 };
3866
3867 void G1CollectedHeap::remove_self_forwarding_pointers() {
3868 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
3869 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3870 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3871 OopsInHeapRegionClosure *cl;
3872 if (G1DeferredRSUpdate) {
3873 cl = &deferred_update;
3874 } else {
3875 cl = &immediate_update;
3876 }
3877 HeapRegion* cur = g1_policy()->collection_set();
3878 while (cur != NULL) {
3879 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3880 assert(!cur->isHumongous(), "sanity");
3881
3882 if (cur->evacuation_failed()) {
3883 assert(cur->in_collection_set(), "bad CS");
3884 RemoveSelfPointerClosure rspc(_g1h, cur, cl);
3885
3886 // In the common case we make sure that this is done when the
3887 // region is freed so that it is "ready-to-go" when it's
3888 // re-allocated. However, when evacuation failure happens, a
3889 // region will remain in the heap and might ultimately be added
3890 // to a CSet in the future. So we have to be careful here and
3891 // make sure the region's RSet is ready for parallel iteration
3892 // whenever this might be required in the future.
3893 cur->rem_set()->reset_for_par_iteration();
3894 cur->reset_bot();
3895 cl->set_region(cur);
3896 cur->object_iterate(&rspc);
3897
3898 // A number of manipulations to make the TAMS be the current top,
3899 // and the marked bytes be the ones observed in the iteration.
3900 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3901 // The comments below are the postconditions achieved by the
3902 // calls. Note especially the last such condition, which says that
3903 // the count of marked bytes has been properly restored.
3904 cur->note_start_of_marking(false);
3905 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3906 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3907 // _next_marked_bytes == prev_marked_bytes.
3908 cur->note_end_of_marking();
3909 // _prev_top_at_mark_start == top(),
3910 // _prev_marked_bytes == prev_marked_bytes
3911 }
3912 // If there is no mark in progress, we modified the _next variables
3913 // above needlessly, but harmlessly.
3914 if (_g1h->mark_in_progress()) {
3915 cur->note_start_of_marking(false);
3916 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3917 // _next_marked_bytes == next_marked_bytes.
3918 }
3919
3920 // Now make sure the region has the right index in the sorted array.
3921 g1_policy()->note_change_in_marked_bytes(cur);
3922 }
3923 cur = cur->next_in_collection_set();
3924 }
3925 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3926
3927 // Now restore saved marks, if any.
3928 if (_objs_with_preserved_marks != NULL) {
3929 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3930 guarantee(_objs_with_preserved_marks->length() ==
3931 _preserved_marks_of_objs->length(), "Both or none.");
3932 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3933 oop obj = _objs_with_preserved_marks->at(i);
3934 markOop m = _preserved_marks_of_objs->at(i);
3935 obj->set_mark(m);
3936 }
3937 // Delete the preserved marks growable arrays (allocated on the C heap).
3938 delete _objs_with_preserved_marks;
3939 delete _preserved_marks_of_objs;
3940 _objs_with_preserved_marks = NULL;
3941 _preserved_marks_of_objs = NULL;
3942 }
3943 }
3944
3945 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3946 _evac_failure_scan_stack->push(obj);
3947 }
3948
3949 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3950 assert(_evac_failure_scan_stack != NULL, "precondition");
3951
3952 while (_evac_failure_scan_stack->length() > 0) {
3953 oop obj = _evac_failure_scan_stack->pop();
3954 _evac_failure_closure->set_region(heap_region_containing(obj));
3955 obj->oop_iterate_backwards(_evac_failure_closure);
3956 }
3957 }
3958
3959 oop
3960 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3961 oop old) {
3962 assert(obj_in_cs(old),
3963 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
3964 (HeapWord*) old));
3965 markOop m = old->mark();
3966 oop forward_ptr = old->forward_to_atomic(old);
3967 if (forward_ptr == NULL) {
3968 // Forward-to-self succeeded.
3969 if (_evac_failure_closure != cl) {
3970 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3971 assert(!_drain_in_progress,
3972 "Should only be true while someone holds the lock.");
3973 // Set the global evac-failure closure to the current thread's.
3974 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3975 set_evac_failure_closure(cl);
3976 // Now do the common part.
3977 handle_evacuation_failure_common(old, m);
3978 // Reset to NULL.
3979 set_evac_failure_closure(NULL);
3980 } else {
3981 // The lock is already held, and this is recursive.
3982 assert(_drain_in_progress, "This should only be the recursive case.");
3983 handle_evacuation_failure_common(old, m);
3984 }
3985 return old;
3986 } else {
3987 // Forward-to-self failed. Either someone else managed to allocate
3988 // space for this object (old != forward_ptr) or they beat us in
3989 // self-forwarding it (old == forward_ptr).
3990 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
3991 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
3992 "should not be in the CSet",
3993 (HeapWord*) old, (HeapWord*) forward_ptr));
3994 return forward_ptr;
3995 }
3996 }
3997
3998 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3999 set_evacuation_failed(true);
4000
4001 preserve_mark_if_necessary(old, m);
4002
4003 HeapRegion* r = heap_region_containing(old);
4004 if (!r->evacuation_failed()) {
4005 r->set_evacuation_failed(true);
4006 _hr_printer.evac_failure(r);
4007 }
4008
4009 push_on_evac_failure_scan_stack(old);
4010
4011 if (!_drain_in_progress) {
4012 // prevent recursion in copy_to_survivor_space()
4013 _drain_in_progress = true;
4014 drain_evac_failure_scan_stack();
4015 _drain_in_progress = false;
4016 }
4017 }
4018
4019 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4020 assert(evacuation_failed(), "Oversaving!");
4021 // We want to call the "for_promotion_failure" version only in the
4022 // case of a promotion failure.
4023 if (m->must_be_preserved_for_promotion_failure(obj)) {
4024 if (_objs_with_preserved_marks == NULL) {
4025 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4026 _objs_with_preserved_marks =
4027 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4028 _preserved_marks_of_objs =
4029 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4030 }
4031 _objs_with_preserved_marks->push(obj);
4032 _preserved_marks_of_objs->push(m);
4033 }
4034 }
4035
4036 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4037 size_t word_size) {
4038 if (purpose == GCAllocForSurvived) {
4039 HeapWord* result = survivor_attempt_allocation(word_size);
4040 if (result != NULL) {
4041 return result;
4042 } else {
4043 // Let's try to allocate in the old gen in case we can fit the
4044 // object there.
4045 return old_attempt_allocation(word_size);
4046 }
4047 } else {
4048 assert(purpose == GCAllocForTenured, "sanity");
4049 HeapWord* result = old_attempt_allocation(word_size);
4050 if (result != NULL) {
4051 return result;
4052 } else {
4053 // Let's try to allocate in the survivors in case we can fit the
4054 // object there.
4055 return survivor_attempt_allocation(word_size);
4056 }
4057 }
4058
4059 ShouldNotReachHere();
4060 // Trying to keep some compilers happy.
4061 return NULL;
4062 }
4063
4064 #ifndef PRODUCT
4065 bool GCLabBitMapClosure::do_bit(size_t offset) {
4066 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4067 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4068 return true;
4069 }
4070 #endif // PRODUCT
4071
4072 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4073 ParGCAllocBuffer(gclab_word_size),
4074 _should_mark_objects(false),
4075 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
4076 _retired(false)
4077 {
4078 //_should_mark_objects is set to true when G1ParCopyHelper needs to
4079 // mark the forwarded location of an evacuated object.
4080 // We set _should_mark_objects to true if marking is active, i.e. when we
4081 // need to propagate a mark, or during an initial mark pause, i.e. when we
4082 // need to mark objects immediately reachable by the roots.
4083 if (G1CollectedHeap::heap()->mark_in_progress() ||
4084 G1CollectedHeap::heap()->g1_policy()->during_initial_mark_pause()) {
4085 _should_mark_objects = true;
4086 }
4087 }
4088
4089 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4090 : _g1h(g1h),
4091 _refs(g1h->task_queue(queue_num)),
4092 _dcq(&g1h->dirty_card_queue_set()),
4093 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4094 _g1_rem(g1h->g1_rem_set()),
4095 _hash_seed(17), _queue_num(queue_num),
4096 _term_attempts(0),
4097 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4098 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4099 _age_table(false),
4100 _strong_roots_time(0), _term_time(0),
4101 _alloc_buffer_waste(0), _undo_waste(0)
4102 {
4103 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4104 // we "sacrifice" entry 0 to keep track of surviving bytes for
4105 // non-young regions (where the age is -1)
4106 // We also add a few elements at the beginning and at the end in
4107 // an attempt to eliminate cache contention
4108 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
4109 size_t array_length = PADDING_ELEM_NUM +
4110 real_length +
4111 PADDING_ELEM_NUM;
4112 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4113 if (_surviving_young_words_base == NULL)
4114 vm_exit_out_of_memory(array_length * sizeof(size_t),
4115 "Not enough space for young surv histo.");
4116 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4117 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4118
4119 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4120 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4121
4122 _start = os::elapsedTime();
4123 }
4124
4125 void
4126 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4127 {
4128 st->print_raw_cr("GC Termination Stats");
4129 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4130 " ------waste (KiB)------");
4131 st->print_raw_cr("thr ms ms % ms % attempts"
4132 " total alloc undo");
4133 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4134 " ------- ------- -------");
4135 }
4136
4137 void
4138 G1ParScanThreadState::print_termination_stats(int i,
4139 outputStream* const st) const
4140 {
4141 const double elapsed_ms = elapsed_time() * 1000.0;
4142 const double s_roots_ms = strong_roots_time() * 1000.0;
4143 const double term_ms = term_time() * 1000.0;
4144 st->print_cr("%3d %9.2f %9.2f %6.2f "
4145 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4146 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4147 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4148 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4149 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4150 alloc_buffer_waste() * HeapWordSize / K,
4151 undo_waste() * HeapWordSize / K);
4152 }
4153
4154 #ifdef ASSERT
4155 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4156 assert(ref != NULL, "invariant");
4157 assert(UseCompressedOops, "sanity");
4158 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4159 oop p = oopDesc::load_decode_heap_oop(ref);
4160 assert(_g1h->is_in_g1_reserved(p),
4161 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4162 return true;
4163 }
4164
4165 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4166 assert(ref != NULL, "invariant");
4167 if (has_partial_array_mask(ref)) {
4168 // Must be in the collection set--it's already been copied.
4169 oop p = clear_partial_array_mask(ref);
4170 assert(_g1h->obj_in_cs(p),
4171 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4172 } else {
4173 oop p = oopDesc::load_decode_heap_oop(ref);
4174 assert(_g1h->is_in_g1_reserved(p),
4175 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4176 }
4177 return true;
4178 }
4179
4180 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4181 if (ref.is_narrow()) {
4182 return verify_ref((narrowOop*) ref);
4183 } else {
4184 return verify_ref((oop*) ref);
4185 }
4186 }
4187 #endif // ASSERT
4188
4189 void G1ParScanThreadState::trim_queue() {
4190 StarTask ref;
4191 do {
4192 // Drain the overflow stack first, so other threads can steal.
4193 while (refs()->pop_overflow(ref)) {
4194 deal_with_reference(ref);
4195 }
4196 while (refs()->pop_local(ref)) {
4197 deal_with_reference(ref);
4198 }
4199 } while (!refs()->is_empty());
4200 }
4201
4202 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4203 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4204 _par_scan_state(par_scan_state),
4205 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4206 _mark_in_progress(_g1->mark_in_progress()) { }
4207
4208 template <class T> void G1ParCopyHelper::mark_object(T* p) {
4209 // This is called from do_oop_work for objects that are not
4210 // in the collection set. Objects in the collection set
4211 // are marked after they have been evacuated.
4212
4213 T heap_oop = oopDesc::load_heap_oop(p);
4214 if (!oopDesc::is_null(heap_oop)) {
4215 oop obj = oopDesc::decode_heap_oop(heap_oop);
4216 HeapWord* addr = (HeapWord*)obj;
4217 if (_g1->is_in_g1_reserved(addr)) {
4218 _cm->grayRoot(oop(addr));
4219 }
4220 }
4221 }
4222
4223 oop G1ParCopyHelper::copy_to_survivor_space(oop old, bool should_mark_copy) {
4224 size_t word_sz = old->size();
4225 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4226 // +1 to make the -1 indexes valid...
4227 int young_index = from_region->young_index_in_cset()+1;
4228 assert( (from_region->is_young() && young_index > 0) ||
4229 (!from_region->is_young() && young_index == 0), "invariant" );
4230 G1CollectorPolicy* g1p = _g1->g1_policy();
4231 markOop m = old->mark();
4232 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4233 : m->age();
4234 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4235 word_sz);
4236 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4237 oop obj = oop(obj_ptr);
4238
4239 if (obj_ptr == NULL) {
4240 // This will either forward-to-self, or detect that someone else has
4241 // installed a forwarding pointer.
4242 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4243 return _g1->handle_evacuation_failure_par(cl, old);
4244 }
4245
4246 // We're going to allocate linearly, so might as well prefetch ahead.
4247 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4248
4249 oop forward_ptr = old->forward_to_atomic(obj);
4250 if (forward_ptr == NULL) {
4251 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4252 if (g1p->track_object_age(alloc_purpose)) {
4253 // We could simply do obj->incr_age(). However, this causes a
4254 // performance issue. obj->incr_age() will first check whether
4255 // the object has a displaced mark by checking its mark word;
4256 // getting the mark word from the new location of the object
4257 // stalls. So, given that we already have the mark word and we
4258 // are about to install it anyway, it's better to increase the
4259 // age on the mark word, when the object does not have a
4260 // displaced mark word. We're not expecting many objects to have
4261 // a displaced marked word, so that case is not optimized
4262 // further (it could be...) and we simply call obj->incr_age().
4263
4264 if (m->has_displaced_mark_helper()) {
4265 // in this case, we have to install the mark word first,
4266 // otherwise obj looks to be forwarded (the old mark word,
4267 // which contains the forward pointer, was copied)
4268 obj->set_mark(m);
4269 obj->incr_age();
4270 } else {
4271 m = m->incr_age();
4272 obj->set_mark(m);
4273 }
4274 _par_scan_state->age_table()->add(obj, word_sz);
4275 } else {
4276 obj->set_mark(m);
4277 }
4278
4279 // Mark the evacuated object or propagate "next" mark bit
4280 if (should_mark_copy) {
4281 if (!use_local_bitmaps ||
4282 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4283 // if we couldn't mark it on the local bitmap (this happens when
4284 // the object was not allocated in the GCLab), we have to bite
4285 // the bullet and do the standard parallel mark
4286 _cm->markAndGrayObjectIfNecessary(obj);
4287 }
4288
4289 if (_g1->isMarkedNext(old)) {
4290 // Unmark the object's old location so that marking
4291 // doesn't think the old object is alive.
4292 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4293 }
4294 }
4295
4296 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4297 surv_young_words[young_index] += word_sz;
4298
4299 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4300 arrayOop(old)->set_length(0);
4301 oop* old_p = set_partial_array_mask(old);
4302 _par_scan_state->push_on_queue(old_p);
4303 } else {
4304 // No point in using the slower heap_region_containing() method,
4305 // given that we know obj is in the heap.
4306 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4307 obj->oop_iterate_backwards(_scanner);
4308 }
4309 } else {
4310 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4311 obj = forward_ptr;
4312 }
4313 return obj;
4314 }
4315
4316 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4317 template <class T>
4318 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4319 ::do_oop_work(T* p) {
4320 oop obj = oopDesc::load_decode_heap_oop(p);
4321 assert(barrier != G1BarrierRS || obj != NULL,
4322 "Precondition: G1BarrierRS implies obj is nonNull");
4323
4324 // Marking:
4325 // If the object is in the collection set, then the thread
4326 // that copies the object should mark, or propagate the
4327 // mark to, the evacuated object.
4328 // If the object is not in the collection set then we
4329 // should call the mark_object() method depending on the
4330 // value of the template parameter do_mark_object (which will
4331 // be true for root scanning closures during an initial mark
4332 // pause).
4333 // The mark_object() method first checks whether the object
4334 // is marked and, if not, attempts to mark the object.
4335
4336 // here the null check is implicit in the cset_fast_test() test
4337 if (_g1->in_cset_fast_test(obj)) {
4338 if (obj->is_forwarded()) {
4339 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4340 // If we are a root scanning closure during an initial
4341 // mark pause (i.e. do_mark_object will be true) then
4342 // we also need to handle marking of roots in the
4343 // event of an evacuation failure. In the event of an
4344 // evacuation failure, the object is forwarded to itself
4345 // and not copied so let's mark it here.
4346 if (do_mark_object && obj->forwardee() == obj) {
4347 mark_object(p);
4348 }
4349 } else {
4350 // We need to mark the copied object if we're a root scanning
4351 // closure during an initial mark pause (i.e. do_mark_object
4352 // will be true), or the object is already marked and we need
4353 // to propagate the mark to the evacuated copy.
4354 bool should_mark_copy = do_mark_object ||
4355 _during_initial_mark ||
4356 (_mark_in_progress && !_g1->is_obj_ill(obj));
4357
4358 oop copy_oop = copy_to_survivor_space(obj, should_mark_copy);
4359 oopDesc::encode_store_heap_oop(p, copy_oop);
4360 }
4361 // When scanning the RS, we only care about objs in CS.
4362 if (barrier == G1BarrierRS) {
4363 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4364 }
4365 } else {
4366 // The object is not in collection set. If we're a root scanning
4367 // closure during an initial mark pause (i.e. do_mark_object will
4368 // be true) then attempt to mark the object.
4369 if (do_mark_object) {
4370 mark_object(p);
4371 }
4372 }
4373
4374 if (barrier == G1BarrierEvac && obj != NULL) {
4375 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4376 }
4377
4378 if (do_gen_barrier && obj != NULL) {
4379 par_do_barrier(p);
4380 }
4381 }
4382
4383 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4384 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4385
4386 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4387 assert(has_partial_array_mask(p), "invariant");
4388 oop old = clear_partial_array_mask(p);
4389 assert(old->is_objArray(), "must be obj array");
4390 assert(old->is_forwarded(), "must be forwarded");
4391 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4392
4393 objArrayOop obj = objArrayOop(old->forwardee());
4394 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4395 // Process ParGCArrayScanChunk elements now
4396 // and push the remainder back onto queue
4397 int start = arrayOop(old)->length();
4398 int end = obj->length();
4399 int remainder = end - start;
4400 assert(start <= end, "just checking");
4401 if (remainder > 2 * ParGCArrayScanChunk) {
4402 // Test above combines last partial chunk with a full chunk
4403 end = start + ParGCArrayScanChunk;
4404 arrayOop(old)->set_length(end);
4405 // Push remainder.
4406 oop* old_p = set_partial_array_mask(old);
4407 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4408 _par_scan_state->push_on_queue(old_p);
4409 } else {
4410 // Restore length so that the heap remains parsable in
4411 // case of evacuation failure.
4412 arrayOop(old)->set_length(end);
4413 }
4414 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4415 // process our set of indices (include header in first chunk)
4416 obj->oop_iterate_range(&_scanner, start, end);
4417 }
4418
4419 class G1ParEvacuateFollowersClosure : public VoidClosure {
4420 protected:
4421 G1CollectedHeap* _g1h;
4422 G1ParScanThreadState* _par_scan_state;
4423 RefToScanQueueSet* _queues;
4424 ParallelTaskTerminator* _terminator;
4425
4426 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4427 RefToScanQueueSet* queues() { return _queues; }
4428 ParallelTaskTerminator* terminator() { return _terminator; }
4429
4430 public:
4431 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4432 G1ParScanThreadState* par_scan_state,
4433 RefToScanQueueSet* queues,
4434 ParallelTaskTerminator* terminator)
4435 : _g1h(g1h), _par_scan_state(par_scan_state),
4436 _queues(queues), _terminator(terminator) {}
4437
4438 void do_void();
4439
4440 private:
4441 inline bool offer_termination();
4442 };
4443
4444 bool G1ParEvacuateFollowersClosure::offer_termination() {
4445 G1ParScanThreadState* const pss = par_scan_state();
4446 pss->start_term_time();
4447 const bool res = terminator()->offer_termination();
4448 pss->end_term_time();
4449 return res;
4450 }
4451
4452 void G1ParEvacuateFollowersClosure::do_void() {
4453 StarTask stolen_task;
4454 G1ParScanThreadState* const pss = par_scan_state();
4455 pss->trim_queue();
4456
4457 do {
4458 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4459 assert(pss->verify_task(stolen_task), "sanity");
4460 if (stolen_task.is_narrow()) {
4461 pss->deal_with_reference((narrowOop*) stolen_task);
4462 } else {
4463 pss->deal_with_reference((oop*) stolen_task);
4464 }
4465
4466 // We've just processed a reference and we might have made
4467 // available new entries on the queues. So we have to make sure
4468 // we drain the queues as necessary.
4469 pss->trim_queue();
4470 }
4471 } while (!offer_termination());
4472
4473 pss->retire_alloc_buffers();
4474 }
4475
4476 class G1ParTask : public AbstractGangTask {
4477 protected:
4478 G1CollectedHeap* _g1h;
4479 RefToScanQueueSet *_queues;
4480 ParallelTaskTerminator _terminator;
4481 int _n_workers;
4482
4483 Mutex _stats_lock;
4484 Mutex* stats_lock() { return &_stats_lock; }
4485
4486 size_t getNCards() {
4487 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4488 / G1BlockOffsetSharedArray::N_bytes;
4489 }
4490
4491 public:
4492 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4493 : AbstractGangTask("G1 collection"),
4494 _g1h(g1h),
4495 _queues(task_queues),
4496 _terminator(workers, _queues),
4497 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4498 _n_workers(workers)
4499 {}
4500
4501 RefToScanQueueSet* queues() { return _queues; }
4502
4503 RefToScanQueue *work_queue(int i) {
4504 return queues()->queue(i);
4505 }
4506
4507 void work(int i) {
4508 if (i >= _n_workers) return; // no work needed this round
4509
4510 double start_time_ms = os::elapsedTime() * 1000.0;
4511 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4512
4513 ResourceMark rm;
4514 HandleMark hm;
4515
4516 G1ParScanThreadState pss(_g1h, i);
4517 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4518 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4519 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4520
4521 pss.set_evac_closure(&scan_evac_cl);
4522 pss.set_evac_failure_closure(&evac_failure_cl);
4523 pss.set_partial_scan_closure(&partial_scan_cl);
4524
4525 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4526 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4527 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4528 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4529
4530 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4531 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4532 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4533
4534 OopsInHeapRegionClosure *scan_root_cl;
4535 OopsInHeapRegionClosure *scan_perm_cl;
4536
4537 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4538 scan_root_cl = &scan_mark_root_cl;
4539 scan_perm_cl = &scan_mark_perm_cl;
4540 } else {
4541 scan_root_cl = &only_scan_root_cl;
4542 scan_perm_cl = &only_scan_perm_cl;
4543 }
4544
4545 pss.start_strong_roots();
4546 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4547 SharedHeap::SO_AllClasses,
4548 scan_root_cl,
4549 &push_heap_rs_cl,
4550 scan_perm_cl,
4551 i);
4552 pss.end_strong_roots();
4553
4554 {
4555 double start = os::elapsedTime();
4556 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4557 evac.do_void();
4558 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4559 double term_ms = pss.term_time()*1000.0;
4560 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4561 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4562 }
4563 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4564 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4565
4566 // Clean up any par-expanded rem sets.
4567 HeapRegionRemSet::par_cleanup();
4568
4569 if (ParallelGCVerbose) {
4570 MutexLocker x(stats_lock());
4571 pss.print_termination_stats(i);
4572 }
4573
4574 assert(pss.refs()->is_empty(), "should be empty");
4575 double end_time_ms = os::elapsedTime() * 1000.0;
4576 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4577 }
4578 };
4579
4580 // *** Common G1 Evacuation Stuff
4581
4582 // This method is run in a GC worker.
4583
4584 void
4585 G1CollectedHeap::
4586 g1_process_strong_roots(bool collecting_perm_gen,
4587 SharedHeap::ScanningOption so,
4588 OopClosure* scan_non_heap_roots,
4589 OopsInHeapRegionClosure* scan_rs,
4590 OopsInGenClosure* scan_perm,
4591 int worker_i) {
4592 // First scan the strong roots, including the perm gen.
4593 double ext_roots_start = os::elapsedTime();
4594 double closure_app_time_sec = 0.0;
4595
4596 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4597 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4598 buf_scan_perm.set_generation(perm_gen());
4599
4600 // Walk the code cache w/o buffering, because StarTask cannot handle
4601 // unaligned oop locations.
4602 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4603
4604 process_strong_roots(false, // no scoping; this is parallel code
4605 collecting_perm_gen, so,
4606 &buf_scan_non_heap_roots,
4607 &eager_scan_code_roots,
4608 &buf_scan_perm);
4609
4610 // Now the ref_processor roots.
4611 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4612 // We need to treat the discovered reference lists as roots and
4613 // keep entries (which are added by the marking threads) on them
4614 // live until they can be processed at the end of marking.
4615 ref_processor()->weak_oops_do(&buf_scan_non_heap_roots);
4616 ref_processor()->oops_do(&buf_scan_non_heap_roots);
4617 }
4618
4619 // Finish up any enqueued closure apps (attributed as object copy time).
4620 buf_scan_non_heap_roots.done();
4621 buf_scan_perm.done();
4622
4623 double ext_roots_end = os::elapsedTime();
4624
4625 g1_policy()->reset_obj_copy_time(worker_i);
4626 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4627 buf_scan_non_heap_roots.closure_app_seconds();
4628 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4629
4630 double ext_root_time_ms =
4631 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4632
4633 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4634
4635 // Scan strong roots in mark stack.
4636 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4637 concurrent_mark()->oops_do(scan_non_heap_roots);
4638 }
4639 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4640 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4641
4642 // Now scan the complement of the collection set.
4643 if (scan_rs != NULL) {
4644 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4645 }
4646
4647 _process_strong_tasks->all_tasks_completed();
4648 }
4649
4650 void
4651 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4652 OopClosure* non_root_closure) {
4653 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4654 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4655 }
4656
4657 void G1CollectedHeap::evacuate_collection_set() {
4658 set_evacuation_failed(false);
4659
4660 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4661 concurrent_g1_refine()->set_use_cache(false);
4662 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4663
4664 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4665 set_par_threads(n_workers);
4666 G1ParTask g1_par_task(this, n_workers, _task_queues);
4667
4668 init_for_evac_failure(NULL);
4669
4670 rem_set()->prepare_for_younger_refs_iterate(true);
4671
4672 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4673 double start_par = os::elapsedTime();
4674 if (G1CollectedHeap::use_parallel_gc_threads()) {
4675 // The individual threads will set their evac-failure closures.
4676 StrongRootsScope srs(this);
4677 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
4678 workers()->run_task(&g1_par_task);
4679 } else {
4680 StrongRootsScope srs(this);
4681 g1_par_task.work(0);
4682 }
4683
4684 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4685 g1_policy()->record_par_time(par_time);
4686 set_par_threads(0);
4687
4688 // Weak root processing.
4689 // Note: when JSR 292 is enabled and code blobs can contain
4690 // non-perm oops then we will need to process the code blobs
4691 // here too.
4692 {
4693 G1IsAliveClosure is_alive(this);
4694 G1KeepAliveClosure keep_alive(this);
4695 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4696 }
4697 release_gc_alloc_regions();
4698 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4699
4700 concurrent_g1_refine()->clear_hot_cache();
4701 concurrent_g1_refine()->set_use_cache(true);
4702
4703 finalize_for_evac_failure();
4704
4705 // Must do this before removing self-forwarding pointers, which clears
4706 // the per-region evac-failure flags.
4707 concurrent_mark()->complete_marking_in_collection_set();
4708
4709 if (evacuation_failed()) {
4710 remove_self_forwarding_pointers();
4711 if (PrintGCDetails) {
4712 gclog_or_tty->print(" (to-space overflow)");
4713 } else if (PrintGC) {
4714 gclog_or_tty->print("--");
4715 }
4716 }
4717
4718 if (G1DeferredRSUpdate) {
4719 RedirtyLoggedCardTableEntryFastClosure redirty;
4720 dirty_card_queue_set().set_closure(&redirty);
4721 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4722
4723 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4724 dcq.merge_bufferlists(&dirty_card_queue_set());
4725 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4726 }
4727 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4728 }
4729
4730 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
4731 size_t* pre_used,
4732 FreeRegionList* free_list,
4733 HumongousRegionSet* humongous_proxy_set,
4734 HRRSCleanupTask* hrrs_cleanup_task,
4735 bool par) {
4736 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
4737 if (hr->isHumongous()) {
4738 assert(hr->startsHumongous(), "we should only see starts humongous");
4739 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
4740 } else {
4741 free_region(hr, pre_used, free_list, par);
4742 }
4743 } else {
4744 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
4745 }
4746 }
4747
4748 void G1CollectedHeap::free_region(HeapRegion* hr,
4749 size_t* pre_used,
4750 FreeRegionList* free_list,
4751 bool par) {
4752 assert(!hr->isHumongous(), "this is only for non-humongous regions");
4753 assert(!hr->is_empty(), "the region should not be empty");
4754 assert(free_list != NULL, "pre-condition");
4755
4756 *pre_used += hr->used();
4757 hr->hr_clear(par, true /* clear_space */);
4758 free_list->add_as_head(hr);
4759 }
4760
4761 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4762 size_t* pre_used,
4763 FreeRegionList* free_list,
4764 HumongousRegionSet* humongous_proxy_set,
4765 bool par) {
4766 assert(hr->startsHumongous(), "this is only for starts humongous regions");
4767 assert(free_list != NULL, "pre-condition");
4768 assert(humongous_proxy_set != NULL, "pre-condition");
4769
4770 size_t hr_used = hr->used();
4771 size_t hr_capacity = hr->capacity();
4772 size_t hr_pre_used = 0;
4773 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
4774 hr->set_notHumongous();
4775 free_region(hr, &hr_pre_used, free_list, par);
4776
4777 size_t i = hr->hrs_index() + 1;
4778 size_t num = 1;
4779 while (i < n_regions()) {
4780 HeapRegion* curr_hr = region_at(i);
4781 if (!curr_hr->continuesHumongous()) {
4782 break;
4783 }
4784 curr_hr->set_notHumongous();
4785 free_region(curr_hr, &hr_pre_used, free_list, par);
4786 num += 1;
4787 i += 1;
4788 }
4789 assert(hr_pre_used == hr_used,
4790 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
4791 "should be the same", hr_pre_used, hr_used));
4792 *pre_used += hr_pre_used;
4793 }
4794
4795 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
4796 FreeRegionList* free_list,
4797 HumongousRegionSet* humongous_proxy_set,
4798 bool par) {
4799 if (pre_used > 0) {
4800 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
4801 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4802 assert(_summary_bytes_used >= pre_used,
4803 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
4804 "should be >= pre_used: "SIZE_FORMAT,
4805 _summary_bytes_used, pre_used));
4806 _summary_bytes_used -= pre_used;
4807 }
4808 if (free_list != NULL && !free_list->is_empty()) {
4809 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4810 _free_list.add_as_head(free_list);
4811 }
4812 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
4813 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4814 _humongous_set.update_from_proxy(humongous_proxy_set);
4815 }
4816 }
4817
4818 class G1ParCleanupCTTask : public AbstractGangTask {
4819 CardTableModRefBS* _ct_bs;
4820 G1CollectedHeap* _g1h;
4821 HeapRegion* volatile _su_head;
4822 public:
4823 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4824 G1CollectedHeap* g1h) :
4825 AbstractGangTask("G1 Par Cleanup CT Task"),
4826 _ct_bs(ct_bs), _g1h(g1h) { }
4827
4828 void work(int i) {
4829 HeapRegion* r;
4830 while (r = _g1h->pop_dirty_cards_region()) {
4831 clear_cards(r);
4832 }
4833 }
4834
4835 void clear_cards(HeapRegion* r) {
4836 // Cards of the survivors should have already been dirtied.
4837 if (!r->is_survivor()) {
4838 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4839 }
4840 }
4841 };
4842
4843 #ifndef PRODUCT
4844 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4845 G1CollectedHeap* _g1h;
4846 CardTableModRefBS* _ct_bs;
4847 public:
4848 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
4849 : _g1h(g1h), _ct_bs(ct_bs) { }
4850 virtual bool doHeapRegion(HeapRegion* r) {
4851 if (r->is_survivor()) {
4852 _g1h->verify_dirty_region(r);
4853 } else {
4854 _g1h->verify_not_dirty_region(r);
4855 }
4856 return false;
4857 }
4858 };
4859
4860 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
4861 // All of the region should be clean.
4862 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
4863 MemRegion mr(hr->bottom(), hr->end());
4864 ct_bs->verify_not_dirty_region(mr);
4865 }
4866
4867 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
4868 // We cannot guarantee that [bottom(),end()] is dirty. Threads
4869 // dirty allocated blocks as they allocate them. The thread that
4870 // retires each region and replaces it with a new one will do a
4871 // maximal allocation to fill in [pre_dummy_top(),end()] but will
4872 // not dirty that area (one less thing to have to do while holding
4873 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
4874 // is dirty.
4875 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
4876 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
4877 ct_bs->verify_dirty_region(mr);
4878 }
4879
4880 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
4881 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
4882 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
4883 verify_dirty_region(hr);
4884 }
4885 }
4886
4887 void G1CollectedHeap::verify_dirty_young_regions() {
4888 verify_dirty_young_list(_young_list->first_region());
4889 verify_dirty_young_list(_young_list->first_survivor_region());
4890 }
4891 #endif
4892
4893 void G1CollectedHeap::cleanUpCardTable() {
4894 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4895 double start = os::elapsedTime();
4896
4897 // Iterate over the dirty cards region list.
4898 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4899
4900 if (ParallelGCThreads > 0) {
4901 set_par_threads(workers()->total_workers());
4902 workers()->run_task(&cleanup_task);
4903 set_par_threads(0);
4904 } else {
4905 while (_dirty_cards_region_list) {
4906 HeapRegion* r = _dirty_cards_region_list;
4907 cleanup_task.clear_cards(r);
4908 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4909 if (_dirty_cards_region_list == r) {
4910 // The last region.
4911 _dirty_cards_region_list = NULL;
4912 }
4913 r->set_next_dirty_cards_region(NULL);
4914 }
4915 }
4916
4917 double elapsed = os::elapsedTime() - start;
4918 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4919 #ifndef PRODUCT
4920 if (G1VerifyCTCleanup || VerifyAfterGC) {
4921 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
4922 heap_region_iterate(&cleanup_verifier);
4923 }
4924 #endif
4925 }
4926
4927 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4928 size_t pre_used = 0;
4929 FreeRegionList local_free_list("Local List for CSet Freeing");
4930
4931 double young_time_ms = 0.0;
4932 double non_young_time_ms = 0.0;
4933
4934 // Since the collection set is a superset of the the young list,
4935 // all we need to do to clear the young list is clear its
4936 // head and length, and unlink any young regions in the code below
4937 _young_list->clear();
4938
4939 G1CollectorPolicy* policy = g1_policy();
4940
4941 double start_sec = os::elapsedTime();
4942 bool non_young = true;
4943
4944 HeapRegion* cur = cs_head;
4945 int age_bound = -1;
4946 size_t rs_lengths = 0;
4947
4948 while (cur != NULL) {
4949 assert(!is_on_master_free_list(cur), "sanity");
4950
4951 if (non_young) {
4952 if (cur->is_young()) {
4953 double end_sec = os::elapsedTime();
4954 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4955 non_young_time_ms += elapsed_ms;
4956
4957 start_sec = os::elapsedTime();
4958 non_young = false;
4959 }
4960 } else {
4961 double end_sec = os::elapsedTime();
4962 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4963 young_time_ms += elapsed_ms;
4964
4965 start_sec = os::elapsedTime();
4966 non_young = true;
4967 }
4968
4969 rs_lengths += cur->rem_set()->occupied();
4970
4971 HeapRegion* next = cur->next_in_collection_set();
4972 assert(cur->in_collection_set(), "bad CS");
4973 cur->set_next_in_collection_set(NULL);
4974 cur->set_in_collection_set(false);
4975
4976 if (cur->is_young()) {
4977 int index = cur->young_index_in_cset();
4978 guarantee( index != -1, "invariant" );
4979 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4980 size_t words_survived = _surviving_young_words[index];
4981 cur->record_surv_words_in_group(words_survived);
4982
4983 // At this point the we have 'popped' cur from the collection set
4984 // (linked via next_in_collection_set()) but it is still in the
4985 // young list (linked via next_young_region()). Clear the
4986 // _next_young_region field.
4987 cur->set_next_young_region(NULL);
4988 } else {
4989 int index = cur->young_index_in_cset();
4990 guarantee( index == -1, "invariant" );
4991 }
4992
4993 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4994 (!cur->is_young() && cur->young_index_in_cset() == -1),
4995 "invariant" );
4996
4997 if (!cur->evacuation_failed()) {
4998 // And the region is empty.
4999 assert(!cur->is_empty(), "Should not have empty regions in a CS.");
5000 free_region(cur, &pre_used, &local_free_list, false /* par */);
5001 } else {
5002 cur->uninstall_surv_rate_group();
5003 if (cur->is_young())
5004 cur->set_young_index_in_cset(-1);
5005 cur->set_not_young();
5006 cur->set_evacuation_failed(false);
5007 }
5008 cur = next;
5009 }
5010
5011 policy->record_max_rs_lengths(rs_lengths);
5012 policy->cset_regions_freed();
5013
5014 double end_sec = os::elapsedTime();
5015 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5016 if (non_young)
5017 non_young_time_ms += elapsed_ms;
5018 else
5019 young_time_ms += elapsed_ms;
5020
5021 update_sets_after_freeing_regions(pre_used, &local_free_list,
5022 NULL /* humongous_proxy_set */,
5023 false /* par */);
5024 policy->record_young_free_cset_time_ms(young_time_ms);
5025 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5026 }
5027
5028 // This routine is similar to the above but does not record
5029 // any policy statistics or update free lists; we are abandoning
5030 // the current incremental collection set in preparation of a
5031 // full collection. After the full GC we will start to build up
5032 // the incremental collection set again.
5033 // This is only called when we're doing a full collection
5034 // and is immediately followed by the tearing down of the young list.
5035
5036 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5037 HeapRegion* cur = cs_head;
5038
5039 while (cur != NULL) {
5040 HeapRegion* next = cur->next_in_collection_set();
5041 assert(cur->in_collection_set(), "bad CS");
5042 cur->set_next_in_collection_set(NULL);
5043 cur->set_in_collection_set(false);
5044 cur->set_young_index_in_cset(-1);
5045 cur = next;
5046 }
5047 }
5048
5049 void G1CollectedHeap::set_free_regions_coming() {
5050 if (G1ConcRegionFreeingVerbose) {
5051 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5052 "setting free regions coming");
5053 }
5054
5055 assert(!free_regions_coming(), "pre-condition");
5056 _free_regions_coming = true;
5057 }
5058
5059 void G1CollectedHeap::reset_free_regions_coming() {
5060 {
5061 assert(free_regions_coming(), "pre-condition");
5062 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5063 _free_regions_coming = false;
5064 SecondaryFreeList_lock->notify_all();
5065 }
5066
5067 if (G1ConcRegionFreeingVerbose) {
5068 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5069 "reset free regions coming");
5070 }
5071 }
5072
5073 void G1CollectedHeap::wait_while_free_regions_coming() {
5074 // Most of the time we won't have to wait, so let's do a quick test
5075 // first before we take the lock.
5076 if (!free_regions_coming()) {
5077 return;
5078 }
5079
5080 if (G1ConcRegionFreeingVerbose) {
5081 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5082 "waiting for free regions");
5083 }
5084
5085 {
5086 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5087 while (free_regions_coming()) {
5088 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5089 }
5090 }
5091
5092 if (G1ConcRegionFreeingVerbose) {
5093 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5094 "done waiting for free regions");
5095 }
5096 }
5097
5098 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5099 assert(heap_lock_held_for_gc(),
5100 "the heap lock should already be held by or for this thread");
5101 _young_list->push_region(hr);
5102 g1_policy()->set_region_short_lived(hr);
5103 }
5104
5105 class NoYoungRegionsClosure: public HeapRegionClosure {
5106 private:
5107 bool _success;
5108 public:
5109 NoYoungRegionsClosure() : _success(true) { }
5110 bool doHeapRegion(HeapRegion* r) {
5111 if (r->is_young()) {
5112 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5113 r->bottom(), r->end());
5114 _success = false;
5115 }
5116 return false;
5117 }
5118 bool success() { return _success; }
5119 };
5120
5121 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5122 bool ret = _young_list->check_list_empty(check_sample);
5123
5124 if (check_heap) {
5125 NoYoungRegionsClosure closure;
5126 heap_region_iterate(&closure);
5127 ret = ret && closure.success();
5128 }
5129
5130 return ret;
5131 }
5132
5133 void G1CollectedHeap::empty_young_list() {
5134 assert(heap_lock_held_for_gc(),
5135 "the heap lock should already be held by or for this thread");
5136
5137 _young_list->empty_list();
5138 }
5139
5140 // Done at the start of full GC.
5141 void G1CollectedHeap::tear_down_region_lists() {
5142 _free_list.remove_all();
5143 }
5144
5145 class RegionResetter: public HeapRegionClosure {
5146 G1CollectedHeap* _g1h;
5147 FreeRegionList _local_free_list;
5148
5149 public:
5150 RegionResetter() : _g1h(G1CollectedHeap::heap()),
5151 _local_free_list("Local Free List for RegionResetter") { }
5152
5153 bool doHeapRegion(HeapRegion* r) {
5154 if (r->continuesHumongous()) return false;
5155 if (r->top() > r->bottom()) {
5156 if (r->top() < r->end()) {
5157 Copy::fill_to_words(r->top(),
5158 pointer_delta(r->end(), r->top()));
5159 }
5160 } else {
5161 assert(r->is_empty(), "tautology");
5162 _local_free_list.add_as_tail(r);
5163 }
5164 return false;
5165 }
5166
5167 void update_free_lists() {
5168 _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL,
5169 false /* par */);
5170 }
5171 };
5172
5173 // Done at the end of full GC.
5174 void G1CollectedHeap::rebuild_region_lists() {
5175 // This needs to go at the end of the full GC.
5176 RegionResetter rs;
5177 heap_region_iterate(&rs);
5178 rs.update_free_lists();
5179 }
5180
5181 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5182 _refine_cte_cl->set_concurrent(concurrent);
5183 }
5184
5185 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5186 HeapRegion* hr = heap_region_containing(p);
5187 if (hr == NULL) {
5188 return is_in_permanent(p);
5189 } else {
5190 return hr->is_in(p);
5191 }
5192 }
5193
5194 // Methods for the mutator alloc region
5195
5196 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5197 bool force) {
5198 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5199 assert(!force || g1_policy()->can_expand_young_list(),
5200 "if force is true we should be able to expand the young list");
5201 bool young_list_full = g1_policy()->is_young_list_full();
5202 if (force || !young_list_full) {
5203 HeapRegion* new_alloc_region = new_region(word_size,
5204 false /* do_expand */);
5205 if (new_alloc_region != NULL) {
5206 g1_policy()->update_region_num(true /* next_is_young */);
5207 set_region_short_lived_locked(new_alloc_region);
5208 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
5209 g1mm()->update_eden_counters();
5210 return new_alloc_region;
5211 }
5212 }
5213 return NULL;
5214 }
5215
5216 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5217 size_t allocated_bytes) {
5218 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5219 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
5220
5221 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5222 _summary_bytes_used += allocated_bytes;
5223 _hr_printer.retire(alloc_region);
5224 }
5225
5226 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
5227 bool force) {
5228 return _g1h->new_mutator_alloc_region(word_size, force);
5229 }
5230
5231 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
5232 size_t allocated_bytes) {
5233 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
5234 }
5235
5236 // Methods for the GC alloc regions
5237
5238 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5239 size_t count,
5240 GCAllocPurpose ap) {
5241 assert(FreeList_lock->owned_by_self(), "pre-condition");
5242
5243 if (count < g1_policy()->max_regions(ap)) {
5244 HeapRegion* new_alloc_region = new_region(word_size,
5245 true /* do_expand */);
5246 if (new_alloc_region != NULL) {
5247 // We really only need to do this for old regions given that we
5248 // should never scan survivors. But it doesn't hurt to do it
5249 // for survivors too.
5250 new_alloc_region->set_saved_mark();
5251 if (ap == GCAllocForSurvived) {
5252 new_alloc_region->set_survivor();
5253 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
5254 } else {
5255 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
5256 }
5257 return new_alloc_region;
5258 } else {
5259 g1_policy()->note_alloc_region_limit_reached(ap);
5260 }
5261 }
5262 return NULL;
5263 }
5264
5265 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5266 size_t allocated_bytes,
5267 GCAllocPurpose ap) {
5268 alloc_region->note_end_of_copying();
5269 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5270 if (ap == GCAllocForSurvived) {
5271 young_list()->add_survivor_region(alloc_region);
5272 }
5273 _hr_printer.retire(alloc_region);
5274 }
5275
5276 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
5277 bool force) {
5278 assert(!force, "not supported for GC alloc regions");
5279 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
5280 }
5281
5282 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
5283 size_t allocated_bytes) {
5284 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
5285 GCAllocForSurvived);
5286 }
5287
5288 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
5289 bool force) {
5290 assert(!force, "not supported for GC alloc regions");
5291 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
5292 }
5293
5294 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
5295 size_t allocated_bytes) {
5296 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
5297 GCAllocForTenured);
5298 }
5299 // Heap region set verification
5300
5301 class VerifyRegionListsClosure : public HeapRegionClosure {
5302 private:
5303 HumongousRegionSet* _humongous_set;
5304 FreeRegionList* _free_list;
5305 size_t _region_count;
5306
5307 public:
5308 VerifyRegionListsClosure(HumongousRegionSet* humongous_set,
5309 FreeRegionList* free_list) :
5310 _humongous_set(humongous_set), _free_list(free_list),
5311 _region_count(0) { }
5312
5313 size_t region_count() { return _region_count; }
5314
5315 bool doHeapRegion(HeapRegion* hr) {
5316 _region_count += 1;
5317
5318 if (hr->continuesHumongous()) {
5319 return false;
5320 }
5321
5322 if (hr->is_young()) {
5323 // TODO
5324 } else if (hr->startsHumongous()) {
5325 _humongous_set->verify_next_region(hr);
5326 } else if (hr->is_empty()) {
5327 _free_list->verify_next_region(hr);
5328 }
5329 return false;
5330 }
5331 };
5332
5333 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index,
5334 HeapWord* bottom) {
5335 HeapWord* end = bottom + HeapRegion::GrainWords;
5336 MemRegion mr(bottom, end);
5337 assert(_g1_reserved.contains(mr), "invariant");
5338 // This might return NULL if the allocation fails
5339 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
5340 }
5341
5342 void G1CollectedHeap::verify_region_sets() {
5343 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5344
5345 // First, check the explicit lists.
5346 _free_list.verify();
5347 {
5348 // Given that a concurrent operation might be adding regions to
5349 // the secondary free list we have to take the lock before
5350 // verifying it.
5351 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5352 _secondary_free_list.verify();
5353 }
5354 _humongous_set.verify();
5355
5356 // If a concurrent region freeing operation is in progress it will
5357 // be difficult to correctly attributed any free regions we come
5358 // across to the correct free list given that they might belong to
5359 // one of several (free_list, secondary_free_list, any local lists,
5360 // etc.). So, if that's the case we will skip the rest of the
5361 // verification operation. Alternatively, waiting for the concurrent
5362 // operation to complete will have a non-trivial effect on the GC's
5363 // operation (no concurrent operation will last longer than the
5364 // interval between two calls to verification) and it might hide
5365 // any issues that we would like to catch during testing.
5366 if (free_regions_coming()) {
5367 return;
5368 }
5369
5370 // Make sure we append the secondary_free_list on the free_list so
5371 // that all free regions we will come across can be safely
5372 // attributed to the free_list.
5373 append_secondary_free_list_if_not_empty_with_lock();
5374
5375 // Finally, make sure that the region accounting in the lists is
5376 // consistent with what we see in the heap.
5377 _humongous_set.verify_start();
5378 _free_list.verify_start();
5379
5380 VerifyRegionListsClosure cl(&_humongous_set, &_free_list);
5381 heap_region_iterate(&cl);
5382
5383 _humongous_set.verify_end();
5384 _free_list.verify_end();
5385 }