1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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/g1ErgoVerbose.hpp"
35 #include "gc_implementation/g1/g1EvacFailure.hpp"
36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
37 #include "gc_implementation/g1/g1Log.hpp"
38 #include "gc_implementation/g1/g1MarkSweep.hpp"
39 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
40 #include "gc_implementation/g1/g1RemSet.inline.hpp"
41 #include "gc_implementation/g1/g1YCTypes.hpp"
42 #include "gc_implementation/g1/heapRegion.inline.hpp"
43 #include "gc_implementation/g1/heapRegionRemSet.hpp"
44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
45 #include "gc_implementation/g1/vm_operations_g1.hpp"
46 #include "gc_implementation/shared/gcHeapSummary.hpp"
47 #include "gc_implementation/shared/gcTimer.hpp"
48 #include "gc_implementation/shared/gcTrace.hpp"
49 #include "gc_implementation/shared/gcTraceTime.hpp"
50 #include "gc_implementation/shared/isGCActiveMark.hpp"
51 #include "memory/gcLocker.inline.hpp"
52 #include "memory/genOopClosures.inline.hpp"
53 #include "memory/generationSpec.hpp"
54 #include "memory/referenceProcessor.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "oops/oop.pcgc.inline.hpp"
57 #include "runtime/aprofiler.hpp"
58 #include "runtime/vmThread.hpp"
59
60 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
61
62 // turn it on so that the contents of the young list (scan-only /
63 // to-be-collected) are printed at "strategic" points before / during
64 // / after the collection --- this is useful for debugging
65 #define YOUNG_LIST_VERBOSE 0
66 // CURRENT STATUS
67 // This file is under construction. Search for "FIXME".
68
69 // INVARIANTS/NOTES
70 //
71 // All allocation activity covered by the G1CollectedHeap interface is
72 // serialized by acquiring the HeapLock. This happens in mem_allocate
73 // and allocate_new_tlab, which are the "entry" points to the
74 // allocation code from the rest of the JVM. (Note that this does not
75 // apply to TLAB allocation, which is not part of this interface: it
76 // is done by clients of this interface.)
77
78 // Notes on implementation of parallelism in different tasks.
79 //
80 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
81 // The number of GC workers is passed to heap_region_par_iterate_chunked().
82 // It does use run_task() which sets _n_workers in the task.
83 // G1ParTask executes g1_process_strong_roots() ->
84 // SharedHeap::process_strong_roots() which calls eventually to
85 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
86 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
87 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
88 //
89
90 // Local to this file.
91
92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
93 SuspendibleThreadSet* _sts;
94 G1RemSet* _g1rs;
95 ConcurrentG1Refine* _cg1r;
96 bool _concurrent;
97 public:
98 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
99 G1RemSet* g1rs,
100 ConcurrentG1Refine* cg1r) :
101 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
102 {}
103 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
104 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
105 // This path is executed by the concurrent refine or mutator threads,
106 // concurrently, and so we do not care if card_ptr contains references
107 // that point into the collection set.
108 assert(!oops_into_cset, "should be");
109
110 if (_concurrent && _sts->should_yield()) {
111 // Caller will actually yield.
112 return false;
113 }
114 // Otherwise, we finished successfully; return true.
115 return true;
116 }
117 void set_concurrent(bool b) { _concurrent = b; }
118 };
119
120
121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
122 int _calls;
123 G1CollectedHeap* _g1h;
124 CardTableModRefBS* _ctbs;
125 int _histo[256];
126 public:
127 ClearLoggedCardTableEntryClosure() :
128 _calls(0)
129 {
130 _g1h = G1CollectedHeap::heap();
131 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
132 for (int i = 0; i < 256; i++) _histo[i] = 0;
133 }
134 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
135 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
136 _calls++;
137 unsigned char* ujb = (unsigned char*)card_ptr;
138 int ind = (int)(*ujb);
139 _histo[ind]++;
140 *card_ptr = -1;
141 }
142 return true;
143 }
144 int calls() { return _calls; }
145 void print_histo() {
146 gclog_or_tty->print_cr("Card table value histogram:");
147 for (int i = 0; i < 256; i++) {
148 if (_histo[i] != 0) {
149 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
150 }
151 }
152 }
153 };
154
155 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
156 int _calls;
157 G1CollectedHeap* _g1h;
158 CardTableModRefBS* _ctbs;
159 public:
160 RedirtyLoggedCardTableEntryClosure() :
161 _calls(0)
162 {
163 _g1h = G1CollectedHeap::heap();
164 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
165 }
166 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
167 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
168 _calls++;
169 *card_ptr = 0;
170 }
171 return true;
172 }
173 int calls() { return _calls; }
174 };
175
176 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
177 public:
178 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
179 *card_ptr = CardTableModRefBS::dirty_card_val();
180 return true;
181 }
182 };
183
184 YoungList::YoungList(G1CollectedHeap* g1h) :
185 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
186 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
187 guarantee(check_list_empty(false), "just making sure...");
188 }
189
190 void YoungList::push_region(HeapRegion *hr) {
191 assert(!hr->is_young(), "should not already be young");
192 assert(hr->get_next_young_region() == NULL, "cause it should!");
193
194 hr->set_next_young_region(_head);
195 _head = hr;
196
197 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
198 ++_length;
199 }
200
201 void YoungList::add_survivor_region(HeapRegion* hr) {
202 assert(hr->is_survivor(), "should be flagged as survivor region");
203 assert(hr->get_next_young_region() == NULL, "cause it should!");
204
205 hr->set_next_young_region(_survivor_head);
206 if (_survivor_head == NULL) {
207 _survivor_tail = hr;
208 }
209 _survivor_head = hr;
210 ++_survivor_length;
211 }
212
213 void YoungList::empty_list(HeapRegion* list) {
214 while (list != NULL) {
215 HeapRegion* next = list->get_next_young_region();
216 list->set_next_young_region(NULL);
217 list->uninstall_surv_rate_group();
218 list->set_not_young();
219 list = next;
220 }
221 }
222
223 void YoungList::empty_list() {
224 assert(check_list_well_formed(), "young list should be well formed");
225
226 empty_list(_head);
227 _head = NULL;
228 _length = 0;
229
230 empty_list(_survivor_head);
231 _survivor_head = NULL;
232 _survivor_tail = NULL;
233 _survivor_length = 0;
234
235 _last_sampled_rs_lengths = 0;
236
237 assert(check_list_empty(false), "just making sure...");
238 }
239
240 bool YoungList::check_list_well_formed() {
241 bool ret = true;
242
243 uint length = 0;
244 HeapRegion* curr = _head;
245 HeapRegion* last = NULL;
246 while (curr != NULL) {
247 if (!curr->is_young()) {
248 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
249 "incorrectly tagged (y: %d, surv: %d)",
250 curr->bottom(), curr->end(),
251 curr->is_young(), curr->is_survivor());
252 ret = false;
253 }
254 ++length;
255 last = curr;
256 curr = curr->get_next_young_region();
257 }
258 ret = ret && (length == _length);
259
260 if (!ret) {
261 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
262 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
263 length, _length);
264 }
265
266 return ret;
267 }
268
269 bool YoungList::check_list_empty(bool check_sample) {
270 bool ret = true;
271
272 if (_length != 0) {
273 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
274 _length);
275 ret = false;
276 }
277 if (check_sample && _last_sampled_rs_lengths != 0) {
278 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
279 ret = false;
280 }
281 if (_head != NULL) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
283 ret = false;
284 }
285 if (!ret) {
286 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
287 }
288
289 return ret;
290 }
291
292 void
293 YoungList::rs_length_sampling_init() {
294 _sampled_rs_lengths = 0;
295 _curr = _head;
296 }
297
298 bool
299 YoungList::rs_length_sampling_more() {
300 return _curr != NULL;
301 }
302
303 void
304 YoungList::rs_length_sampling_next() {
305 assert( _curr != NULL, "invariant" );
306 size_t rs_length = _curr->rem_set()->occupied();
307
308 _sampled_rs_lengths += rs_length;
309
310 // The current region may not yet have been added to the
311 // incremental collection set (it gets added when it is
312 // retired as the current allocation region).
313 if (_curr->in_collection_set()) {
314 // Update the collection set policy information for this region
315 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
316 }
317
318 _curr = _curr->get_next_young_region();
319 if (_curr == NULL) {
320 _last_sampled_rs_lengths = _sampled_rs_lengths;
321 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
322 }
323 }
324
325 void
326 YoungList::reset_auxilary_lists() {
327 guarantee( is_empty(), "young list should be empty" );
328 assert(check_list_well_formed(), "young list should be well formed");
329
330 // Add survivor regions to SurvRateGroup.
331 _g1h->g1_policy()->note_start_adding_survivor_regions();
332 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
333
334 int young_index_in_cset = 0;
335 for (HeapRegion* curr = _survivor_head;
336 curr != NULL;
337 curr = curr->get_next_young_region()) {
338 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
339
340 // The region is a non-empty survivor so let's add it to
341 // the incremental collection set for the next evacuation
342 // pause.
343 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
344 young_index_in_cset += 1;
345 }
346 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
347 _g1h->g1_policy()->note_stop_adding_survivor_regions();
348
349 _head = _survivor_head;
350 _length = _survivor_length;
351 if (_survivor_head != NULL) {
352 assert(_survivor_tail != NULL, "cause it shouldn't be");
353 assert(_survivor_length > 0, "invariant");
354 _survivor_tail->set_next_young_region(NULL);
355 }
356
357 // Don't clear the survivor list handles until the start of
358 // the next evacuation pause - we need it in order to re-tag
359 // the survivor regions from this evacuation pause as 'young'
360 // at the start of the next.
361
362 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
363
364 assert(check_list_well_formed(), "young list should be well formed");
365 }
366
367 void YoungList::print() {
368 HeapRegion* lists[] = {_head, _survivor_head};
369 const char* names[] = {"YOUNG", "SURVIVOR"};
370
371 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
372 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
373 HeapRegion *curr = lists[list];
374 if (curr == NULL)
375 gclog_or_tty->print_cr(" empty");
376 while (curr != NULL) {
377 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
378 HR_FORMAT_PARAMS(curr),
379 curr->prev_top_at_mark_start(),
380 curr->next_top_at_mark_start(),
381 curr->age_in_surv_rate_group_cond());
382 curr = curr->get_next_young_region();
383 }
384 }
385
386 gclog_or_tty->print_cr("");
387 }
388
389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
390 {
391 // Claim the right to put the region on the dirty cards region list
392 // by installing a self pointer.
393 HeapRegion* next = hr->get_next_dirty_cards_region();
394 if (next == NULL) {
395 HeapRegion* res = (HeapRegion*)
396 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
397 NULL);
398 if (res == NULL) {
399 HeapRegion* head;
400 do {
401 // Put the region to the dirty cards region list.
402 head = _dirty_cards_region_list;
403 next = (HeapRegion*)
404 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
405 if (next == head) {
406 assert(hr->get_next_dirty_cards_region() == hr,
407 "hr->get_next_dirty_cards_region() != hr");
408 if (next == NULL) {
409 // The last region in the list points to itself.
410 hr->set_next_dirty_cards_region(hr);
411 } else {
412 hr->set_next_dirty_cards_region(next);
413 }
414 }
415 } while (next != head);
416 }
417 }
418 }
419
420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
421 {
422 HeapRegion* head;
423 HeapRegion* hr;
424 do {
425 head = _dirty_cards_region_list;
426 if (head == NULL) {
427 return NULL;
428 }
429 HeapRegion* new_head = head->get_next_dirty_cards_region();
430 if (head == new_head) {
431 // The last region.
432 new_head = NULL;
433 }
434 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
435 head);
436 } while (hr != head);
437 assert(hr != NULL, "invariant");
438 hr->set_next_dirty_cards_region(NULL);
439 return hr;
440 }
441
442 void G1CollectedHeap::stop_conc_gc_threads() {
443 _cg1r->stop();
444 _cmThread->stop();
445 }
446
447 #ifdef ASSERT
448 // A region is added to the collection set as it is retired
449 // so an address p can point to a region which will be in the
450 // collection set but has not yet been retired. This method
451 // therefore is only accurate during a GC pause after all
452 // regions have been retired. It is used for debugging
453 // to check if an nmethod has references to objects that can
454 // be move during a partial collection. Though it can be
455 // inaccurate, it is sufficient for G1 because the conservative
456 // implementation of is_scavengable() for G1 will indicate that
457 // all nmethods must be scanned during a partial collection.
458 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
459 HeapRegion* hr = heap_region_containing(p);
460 return hr != NULL && hr->in_collection_set();
461 }
462 #endif
463
464 // Returns true if the reference points to an object that
465 // can move in an incremental collection.
466 bool G1CollectedHeap::is_scavengable(const void* p) {
467 G1CollectedHeap* g1h = G1CollectedHeap::heap();
468 G1CollectorPolicy* g1p = g1h->g1_policy();
469 HeapRegion* hr = heap_region_containing(p);
470 if (hr == NULL) {
471 // perm gen (or null)
472 return false;
473 } else {
474 return !hr->isHumongous();
475 }
476 }
477
478 void G1CollectedHeap::check_ct_logs_at_safepoint() {
479 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
480 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
481
482 // Count the dirty cards at the start.
483 CountNonCleanMemRegionClosure count1(this);
484 ct_bs->mod_card_iterate(&count1);
485 int orig_count = count1.n();
486
487 // First clear the logged cards.
488 ClearLoggedCardTableEntryClosure clear;
489 dcqs.set_closure(&clear);
490 dcqs.apply_closure_to_all_completed_buffers();
491 dcqs.iterate_closure_all_threads(false);
492 clear.print_histo();
493
494 // Now ensure that there's no dirty cards.
495 CountNonCleanMemRegionClosure count2(this);
496 ct_bs->mod_card_iterate(&count2);
497 if (count2.n() != 0) {
498 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
499 count2.n(), orig_count);
500 }
501 guarantee(count2.n() == 0, "Card table should be clean.");
502
503 RedirtyLoggedCardTableEntryClosure redirty;
504 JavaThread::dirty_card_queue_set().set_closure(&redirty);
505 dcqs.apply_closure_to_all_completed_buffers();
506 dcqs.iterate_closure_all_threads(false);
507 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
508 clear.calls(), orig_count);
509 guarantee(redirty.calls() == clear.calls(),
510 "Or else mechanism is broken.");
511
512 CountNonCleanMemRegionClosure count3(this);
513 ct_bs->mod_card_iterate(&count3);
514 if (count3.n() != orig_count) {
515 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
516 orig_count, count3.n());
517 guarantee(count3.n() >= orig_count, "Should have restored them all.");
518 }
519
520 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
521 }
522
523 // Private class members.
524
525 G1CollectedHeap* G1CollectedHeap::_g1h;
526
527 // Private methods.
528
529 HeapRegion*
530 G1CollectedHeap::new_region_try_secondary_free_list() {
531 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
532 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
533 if (!_secondary_free_list.is_empty()) {
534 if (G1ConcRegionFreeingVerbose) {
535 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
536 "secondary_free_list has %u entries",
537 _secondary_free_list.length());
538 }
539 // It looks as if there are free regions available on the
540 // secondary_free_list. Let's move them to the free_list and try
541 // again to allocate from it.
542 append_secondary_free_list();
543
544 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
545 "empty we should have moved at least one entry to the free_list");
546 HeapRegion* res = _free_list.remove_head();
547 if (G1ConcRegionFreeingVerbose) {
548 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
549 "allocated "HR_FORMAT" from secondary_free_list",
550 HR_FORMAT_PARAMS(res));
551 }
552 return res;
553 }
554
555 // Wait here until we get notified either when (a) there are no
556 // more free regions coming or (b) some regions have been moved on
557 // the secondary_free_list.
558 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
559 }
560
561 if (G1ConcRegionFreeingVerbose) {
562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
563 "could not allocate from secondary_free_list");
564 }
565 return NULL;
566 }
567
568 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
569 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
570 "the only time we use this to allocate a humongous region is "
571 "when we are allocating a single humongous region");
572
573 HeapRegion* res;
574 if (G1StressConcRegionFreeing) {
575 if (!_secondary_free_list.is_empty()) {
576 if (G1ConcRegionFreeingVerbose) {
577 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
578 "forced to look at the secondary_free_list");
579 }
580 res = new_region_try_secondary_free_list();
581 if (res != NULL) {
582 return res;
583 }
584 }
585 }
586 res = _free_list.remove_head_or_null();
587 if (res == NULL) {
588 if (G1ConcRegionFreeingVerbose) {
589 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
590 "res == NULL, trying the secondary_free_list");
591 }
592 res = new_region_try_secondary_free_list();
593 }
594 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
595 // Currently, only attempts to allocate GC alloc regions set
596 // do_expand to true. So, we should only reach here during a
597 // safepoint. If this assumption changes we might have to
598 // reconsider the use of _expand_heap_after_alloc_failure.
599 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
600
601 ergo_verbose1(ErgoHeapSizing,
602 "attempt heap expansion",
603 ergo_format_reason("region allocation request failed")
604 ergo_format_byte("allocation request"),
605 word_size * HeapWordSize);
606 if (expand(word_size * HeapWordSize)) {
607 // Given that expand() succeeded in expanding the heap, and we
608 // always expand the heap by an amount aligned to the heap
609 // region size, the free list should in theory not be empty. So
610 // it would probably be OK to use remove_head(). But the extra
611 // check for NULL is unlikely to be a performance issue here (we
612 // just expanded the heap!) so let's just be conservative and
613 // use remove_head_or_null().
614 res = _free_list.remove_head_or_null();
615 } else {
616 _expand_heap_after_alloc_failure = false;
617 }
618 }
619 return res;
620 }
621
622 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
623 size_t word_size) {
624 assert(isHumongous(word_size), "word_size should be humongous");
625 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
626
627 uint first = G1_NULL_HRS_INDEX;
628 if (num_regions == 1) {
629 // Only one region to allocate, no need to go through the slower
630 // path. The caller will attempt the expansion if this fails, so
631 // let's not try to expand here too.
632 HeapRegion* hr = new_region(word_size, false /* do_expand */);
633 if (hr != NULL) {
634 first = hr->hrs_index();
635 } else {
636 first = G1_NULL_HRS_INDEX;
637 }
638 } else {
639 // We can't allocate humongous regions while cleanupComplete() is
640 // running, since some of the regions we find to be empty might not
641 // yet be added to the free list and it is not straightforward to
642 // know which list they are on so that we can remove them. Note
643 // that we only need to do this if we need to allocate more than
644 // one region to satisfy the current humongous allocation
645 // request. If we are only allocating one region we use the common
646 // region allocation code (see above).
647 wait_while_free_regions_coming();
648 append_secondary_free_list_if_not_empty_with_lock();
649
650 if (free_regions() >= num_regions) {
651 first = _hrs.find_contiguous(num_regions);
652 if (first != G1_NULL_HRS_INDEX) {
653 for (uint i = first; i < first + num_regions; ++i) {
654 HeapRegion* hr = region_at(i);
655 assert(hr->is_empty(), "sanity");
656 assert(is_on_master_free_list(hr), "sanity");
657 hr->set_pending_removal(true);
658 }
659 _free_list.remove_all_pending(num_regions);
660 }
661 }
662 }
663 return first;
664 }
665
666 HeapWord*
667 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
668 uint num_regions,
669 size_t word_size) {
670 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
671 assert(isHumongous(word_size), "word_size should be humongous");
672 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
673
674 // Index of last region in the series + 1.
675 uint last = first + num_regions;
676
677 // We need to initialize the region(s) we just discovered. This is
678 // a bit tricky given that it can happen concurrently with
679 // refinement threads refining cards on these regions and
680 // potentially wanting to refine the BOT as they are scanning
681 // those cards (this can happen shortly after a cleanup; see CR
682 // 6991377). So we have to set up the region(s) carefully and in
683 // a specific order.
684
685 // The word size sum of all the regions we will allocate.
686 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
687 assert(word_size <= word_size_sum, "sanity");
688
689 // This will be the "starts humongous" region.
690 HeapRegion* first_hr = region_at(first);
691 // The header of the new object will be placed at the bottom of
692 // the first region.
693 HeapWord* new_obj = first_hr->bottom();
694 // This will be the new end of the first region in the series that
695 // should also match the end of the last region in the series.
696 HeapWord* new_end = new_obj + word_size_sum;
697 // This will be the new top of the first region that will reflect
698 // this allocation.
699 HeapWord* new_top = new_obj + word_size;
700
701 // First, we need to zero the header of the space that we will be
702 // allocating. When we update top further down, some refinement
703 // threads might try to scan the region. By zeroing the header we
704 // ensure that any thread that will try to scan the region will
705 // come across the zero klass word and bail out.
706 //
707 // NOTE: It would not have been correct to have used
708 // CollectedHeap::fill_with_object() and make the space look like
709 // an int array. The thread that is doing the allocation will
710 // later update the object header to a potentially different array
711 // type and, for a very short period of time, the klass and length
712 // fields will be inconsistent. This could cause a refinement
713 // thread to calculate the object size incorrectly.
714 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
715
716 // We will set up the first region as "starts humongous". This
717 // will also update the BOT covering all the regions to reflect
718 // that there is a single object that starts at the bottom of the
719 // first region.
720 first_hr->set_startsHumongous(new_top, new_end);
721
722 // Then, if there are any, we will set up the "continues
723 // humongous" regions.
724 HeapRegion* hr = NULL;
725 for (uint i = first + 1; i < last; ++i) {
726 hr = region_at(i);
727 hr->set_continuesHumongous(first_hr);
728 }
729 // If we have "continues humongous" regions (hr != NULL), then the
730 // end of the last one should match new_end.
731 assert(hr == NULL || hr->end() == new_end, "sanity");
732
733 // Up to this point no concurrent thread would have been able to
734 // do any scanning on any region in this series. All the top
735 // fields still point to bottom, so the intersection between
736 // [bottom,top] and [card_start,card_end] will be empty. Before we
737 // update the top fields, we'll do a storestore to make sure that
738 // no thread sees the update to top before the zeroing of the
739 // object header and the BOT initialization.
740 OrderAccess::storestore();
741
742 // Now that the BOT and the object header have been initialized,
743 // we can update top of the "starts humongous" region.
744 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
745 "new_top should be in this region");
746 first_hr->set_top(new_top);
747 if (_hr_printer.is_active()) {
748 HeapWord* bottom = first_hr->bottom();
749 HeapWord* end = first_hr->orig_end();
750 if ((first + 1) == last) {
751 // the series has a single humongous region
752 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
753 } else {
754 // the series has more than one humongous regions
755 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
756 }
757 }
758
759 // Now, we will update the top fields of the "continues humongous"
760 // regions. The reason we need to do this is that, otherwise,
761 // these regions would look empty and this will confuse parts of
762 // G1. For example, the code that looks for a consecutive number
763 // of empty regions will consider them empty and try to
764 // re-allocate them. We can extend is_empty() to also include
765 // !continuesHumongous(), but it is easier to just update the top
766 // fields here. The way we set top for all regions (i.e., top ==
767 // end for all regions but the last one, top == new_top for the
768 // last one) is actually used when we will free up the humongous
769 // region in free_humongous_region().
770 hr = NULL;
771 for (uint i = first + 1; i < last; ++i) {
772 hr = region_at(i);
773 if ((i + 1) == last) {
774 // last continues humongous region
775 assert(hr->bottom() < new_top && new_top <= hr->end(),
776 "new_top should fall on this region");
777 hr->set_top(new_top);
778 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
779 } else {
780 // not last one
781 assert(new_top > hr->end(), "new_top should be above this region");
782 hr->set_top(hr->end());
783 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
784 }
785 }
786 // If we have continues humongous regions (hr != NULL), then the
787 // end of the last one should match new_end and its top should
788 // match new_top.
789 assert(hr == NULL ||
790 (hr->end() == new_end && hr->top() == new_top), "sanity");
791
792 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
793 _summary_bytes_used += first_hr->used();
794 _humongous_set.add(first_hr);
795
796 return new_obj;
797 }
798
799 // If could fit into free regions w/o expansion, try.
800 // Otherwise, if can expand, do so.
801 // Otherwise, if using ex regions might help, try with ex given back.
802 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
803 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
804
805 verify_region_sets_optional();
806
807 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
808 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
809 uint x_num = expansion_regions();
810 uint fs = _hrs.free_suffix();
811 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
812 if (first == G1_NULL_HRS_INDEX) {
813 // The only thing we can do now is attempt expansion.
814 if (fs + x_num >= num_regions) {
815 // If the number of regions we're trying to allocate for this
816 // object is at most the number of regions in the free suffix,
817 // then the call to humongous_obj_allocate_find_first() above
818 // should have succeeded and we wouldn't be here.
819 //
820 // We should only be trying to expand when the free suffix is
821 // not sufficient for the object _and_ we have some expansion
822 // room available.
823 assert(num_regions > fs, "earlier allocation should have succeeded");
824
825 ergo_verbose1(ErgoHeapSizing,
826 "attempt heap expansion",
827 ergo_format_reason("humongous allocation request failed")
828 ergo_format_byte("allocation request"),
829 word_size * HeapWordSize);
830 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
831 // Even though the heap was expanded, it might not have
832 // reached the desired size. So, we cannot assume that the
833 // allocation will succeed.
834 first = humongous_obj_allocate_find_first(num_regions, word_size);
835 }
836 }
837 }
838
839 HeapWord* result = NULL;
840 if (first != G1_NULL_HRS_INDEX) {
841 result =
842 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
843 assert(result != NULL, "it should always return a valid result");
844
845 // A successful humongous object allocation changes the used space
846 // information of the old generation so we need to recalculate the
847 // sizes and update the jstat counters here.
848 g1mm()->update_sizes();
849 }
850
851 verify_region_sets_optional();
852
853 return result;
854 }
855
856 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
857 assert_heap_not_locked_and_not_at_safepoint();
858 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
859
860 unsigned int dummy_gc_count_before;
861 return attempt_allocation(word_size, &dummy_gc_count_before);
862 }
863
864 HeapWord*
865 G1CollectedHeap::mem_allocate(size_t word_size,
866 bool* gc_overhead_limit_was_exceeded) {
867 assert_heap_not_locked_and_not_at_safepoint();
868
869 // Loop until the allocation is satisfied, or unsatisfied after GC.
870 for (int try_count = 1; /* we'll return */; try_count += 1) {
871 unsigned int gc_count_before;
872
873 HeapWord* result = NULL;
874 if (!isHumongous(word_size)) {
875 result = attempt_allocation(word_size, &gc_count_before);
876 } else {
877 result = attempt_allocation_humongous(word_size, &gc_count_before);
878 }
879 if (result != NULL) {
880 return result;
881 }
882
883 // Create the garbage collection operation...
884 VM_G1CollectForAllocation op(gc_count_before, word_size);
885 // ...and get the VM thread to execute it.
886 VMThread::execute(&op);
887
888 if (op.prologue_succeeded() && op.pause_succeeded()) {
889 // If the operation was successful we'll return the result even
890 // if it is NULL. If the allocation attempt failed immediately
891 // after a Full GC, it's unlikely we'll be able to allocate now.
892 HeapWord* result = op.result();
893 if (result != NULL && !isHumongous(word_size)) {
894 // Allocations that take place on VM operations do not do any
895 // card dirtying and we have to do it here. We only have to do
896 // this for non-humongous allocations, though.
897 dirty_young_block(result, word_size);
898 }
899 return result;
900 } else {
901 assert(op.result() == NULL,
902 "the result should be NULL if the VM op did not succeed");
903 }
904
905 // Give a warning if we seem to be looping forever.
906 if ((QueuedAllocationWarningCount > 0) &&
907 (try_count % QueuedAllocationWarningCount == 0)) {
908 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 return NULL;
914 }
915
916 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
917 unsigned int *gc_count_before_ret) {
918 // Make sure you read the note in attempt_allocation_humongous().
919
920 assert_heap_not_locked_and_not_at_safepoint();
921 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
922 "be called for humongous allocation requests");
923
924 // We should only get here after the first-level allocation attempt
925 // (attempt_allocation()) failed to allocate.
926
927 // We will loop until a) we manage to successfully perform the
928 // allocation or b) we successfully schedule a collection which
929 // fails to perform the allocation. b) is the only case when we'll
930 // return NULL.
931 HeapWord* result = NULL;
932 for (int try_count = 1; /* we'll return */; try_count += 1) {
933 bool should_try_gc;
934 unsigned int gc_count_before;
935
936 {
937 MutexLockerEx x(Heap_lock);
938
939 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
940 false /* bot_updates */);
941 if (result != NULL) {
942 return result;
943 }
944
945 // If we reach here, attempt_allocation_locked() above failed to
946 // allocate a new region. So the mutator alloc region should be NULL.
947 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
948
949 if (GC_locker::is_active_and_needs_gc()) {
950 if (g1_policy()->can_expand_young_list()) {
951 // No need for an ergo verbose message here,
952 // can_expand_young_list() does this when it returns true.
953 result = _mutator_alloc_region.attempt_allocation_force(word_size,
954 false /* bot_updates */);
955 if (result != NULL) {
956 return result;
957 }
958 }
959 should_try_gc = false;
960 } else {
961 // The GCLocker may not be active but the GCLocker initiated
962 // GC may not yet have been performed (GCLocker::needs_gc()
963 // returns true). In this case we do not try this GC and
964 // wait until the GCLocker initiated GC is performed, and
965 // then retry the allocation.
966 if (GC_locker::needs_gc()) {
967 should_try_gc = false;
968 } else {
969 // Read the GC count while still holding the Heap_lock.
970 gc_count_before = total_collections();
971 should_try_gc = true;
972 }
973 }
974 }
975
976 if (should_try_gc) {
977 bool succeeded;
978 result = do_collection_pause(word_size, gc_count_before, &succeeded);
979 if (result != NULL) {
980 assert(succeeded, "only way to get back a non-NULL result");
981 return result;
982 }
983
984 if (succeeded) {
985 // If we get here we successfully scheduled a collection which
986 // failed to allocate. No point in trying to allocate
987 // further. We'll just return NULL.
988 MutexLockerEx x(Heap_lock);
989 *gc_count_before_ret = total_collections();
990 return NULL;
991 }
992 } else {
993 // The GCLocker is either active or the GCLocker initiated
994 // GC has not yet been performed. Stall until it is and
995 // then retry the allocation.
996 GC_locker::stall_until_clear();
997 }
998
999 // We can reach here if we were unsuccessful in scheduling a
1000 // collection (because another thread beat us to it) or if we were
1001 // stalled due to the GC locker. In either can we should retry the
1002 // allocation attempt in case another thread successfully
1003 // performed a collection and reclaimed enough space. We do the
1004 // first attempt (without holding the Heap_lock) here and the
1005 // follow-on attempt will be at the start of the next loop
1006 // iteration (after taking the Heap_lock).
1007 result = _mutator_alloc_region.attempt_allocation(word_size,
1008 false /* bot_updates */);
1009 if (result != NULL) {
1010 return result;
1011 }
1012
1013 // Give a warning if we seem to be looping forever.
1014 if ((QueuedAllocationWarningCount > 0) &&
1015 (try_count % QueuedAllocationWarningCount == 0)) {
1016 warning("G1CollectedHeap::attempt_allocation_slow() "
1017 "retries %d times", try_count);
1018 }
1019 }
1020
1021 ShouldNotReachHere();
1022 return NULL;
1023 }
1024
1025 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1026 unsigned int * gc_count_before_ret) {
1027 // The structure of this method has a lot of similarities to
1028 // attempt_allocation_slow(). The reason these two were not merged
1029 // into a single one is that such a method would require several "if
1030 // allocation is not humongous do this, otherwise do that"
1031 // conditional paths which would obscure its flow. In fact, an early
1032 // version of this code did use a unified method which was harder to
1033 // follow and, as a result, it had subtle bugs that were hard to
1034 // track down. So keeping these two methods separate allows each to
1035 // be more readable. It will be good to keep these two in sync as
1036 // much as possible.
1037
1038 assert_heap_not_locked_and_not_at_safepoint();
1039 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1040 "should only be called for humongous allocations");
1041
1042 // Humongous objects can exhaust the heap quickly, so we should check if we
1043 // need to start a marking cycle at each humongous object allocation. We do
1044 // the check before we do the actual allocation. The reason for doing it
1045 // before the allocation is that we avoid having to keep track of the newly
1046 // allocated memory while we do a GC.
1047 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1048 word_size)) {
1049 collect(GCCause::_g1_humongous_allocation);
1050 }
1051
1052 // We will loop until a) we manage to successfully perform the
1053 // allocation or b) we successfully schedule a collection which
1054 // fails to perform the allocation. b) is the only case when we'll
1055 // return NULL.
1056 HeapWord* result = NULL;
1057 for (int try_count = 1; /* we'll return */; try_count += 1) {
1058 bool should_try_gc;
1059 unsigned int gc_count_before;
1060
1061 {
1062 MutexLockerEx x(Heap_lock);
1063
1064 // Given that humongous objects are not allocated in young
1065 // regions, we'll first try to do the allocation without doing a
1066 // collection hoping that there's enough space in the heap.
1067 result = humongous_obj_allocate(word_size);
1068 if (result != NULL) {
1069 return result;
1070 }
1071
1072 if (GC_locker::is_active_and_needs_gc()) {
1073 should_try_gc = false;
1074 } else {
1075 // The GCLocker may not be active but the GCLocker initiated
1076 // GC may not yet have been performed (GCLocker::needs_gc()
1077 // returns true). In this case we do not try this GC and
1078 // wait until the GCLocker initiated GC is performed, and
1079 // then retry the allocation.
1080 if (GC_locker::needs_gc()) {
1081 should_try_gc = false;
1082 } else {
1083 // Read the GC count while still holding the Heap_lock.
1084 gc_count_before = total_collections();
1085 should_try_gc = true;
1086 }
1087 }
1088 }
1089
1090 if (should_try_gc) {
1091 // If we failed to allocate the humongous object, we should try to
1092 // do a collection pause (if we're allowed) in case it reclaims
1093 // enough space for the allocation to succeed after the pause.
1094
1095 bool succeeded;
1096 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1097 if (result != NULL) {
1098 assert(succeeded, "only way to get back a non-NULL result");
1099 return result;
1100 }
1101
1102 if (succeeded) {
1103 // If we get here we successfully scheduled a collection which
1104 // failed to allocate. No point in trying to allocate
1105 // further. We'll just return NULL.
1106 MutexLockerEx x(Heap_lock);
1107 *gc_count_before_ret = total_collections();
1108 return NULL;
1109 }
1110 } else {
1111 // The GCLocker is either active or the GCLocker initiated
1112 // GC has not yet been performed. Stall until it is and
1113 // then retry the allocation.
1114 GC_locker::stall_until_clear();
1115 }
1116
1117 // We can reach here if we were unsuccessful in scheduling a
1118 // collection (because another thread beat us to it) or if we were
1119 // stalled due to the GC locker. In either can we should retry the
1120 // allocation attempt in case another thread successfully
1121 // performed a collection and reclaimed enough space. Give a
1122 // warning if we seem to be looping forever.
1123
1124 if ((QueuedAllocationWarningCount > 0) &&
1125 (try_count % QueuedAllocationWarningCount == 0)) {
1126 warning("G1CollectedHeap::attempt_allocation_humongous() "
1127 "retries %d times", try_count);
1128 }
1129 }
1130
1131 ShouldNotReachHere();
1132 return NULL;
1133 }
1134
1135 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1136 bool expect_null_mutator_alloc_region) {
1137 assert_at_safepoint(true /* should_be_vm_thread */);
1138 assert(_mutator_alloc_region.get() == NULL ||
1139 !expect_null_mutator_alloc_region,
1140 "the current alloc region was unexpectedly found to be non-NULL");
1141
1142 if (!isHumongous(word_size)) {
1143 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1144 false /* bot_updates */);
1145 } else {
1146 HeapWord* result = humongous_obj_allocate(word_size);
1147 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1148 g1_policy()->set_initiate_conc_mark_if_possible();
1149 }
1150 return result;
1151 }
1152
1153 ShouldNotReachHere();
1154 }
1155
1156 class PostMCRemSetClearClosure: public HeapRegionClosure {
1157 G1CollectedHeap* _g1h;
1158 ModRefBarrierSet* _mr_bs;
1159 public:
1160 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1161 _g1h(g1h), _mr_bs(mr_bs) { }
1162 bool doHeapRegion(HeapRegion* r) {
1163 if (r->continuesHumongous()) {
1164 return false;
1165 }
1166 _g1h->reset_gc_time_stamps(r);
1167 HeapRegionRemSet* hrrs = r->rem_set();
1168 if (hrrs != NULL) hrrs->clear();
1169 // You might think here that we could clear just the cards
1170 // corresponding to the used region. But no: if we leave a dirty card
1171 // in a region we might allocate into, then it would prevent that card
1172 // from being enqueued, and cause it to be missed.
1173 // Re: the performance cost: we shouldn't be doing full GC anyway!
1174 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1175 return false;
1176 }
1177 };
1178
1179 void G1CollectedHeap::clear_rsets_post_compaction() {
1180 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1181 heap_region_iterate(&rs_clear);
1182 }
1183
1184 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1185 G1CollectedHeap* _g1h;
1186 UpdateRSOopClosure _cl;
1187 int _worker_i;
1188 public:
1189 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1190 _cl(g1->g1_rem_set(), worker_i),
1191 _worker_i(worker_i),
1192 _g1h(g1)
1193 { }
1194
1195 bool doHeapRegion(HeapRegion* r) {
1196 if (!r->continuesHumongous()) {
1197 _cl.set_from(r);
1198 r->oop_iterate(&_cl);
1199 }
1200 return false;
1201 }
1202 };
1203
1204 class ParRebuildRSTask: public AbstractGangTask {
1205 G1CollectedHeap* _g1;
1206 public:
1207 ParRebuildRSTask(G1CollectedHeap* g1)
1208 : AbstractGangTask("ParRebuildRSTask"),
1209 _g1(g1)
1210 { }
1211
1212 void work(uint worker_id) {
1213 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1214 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1215 _g1->workers()->active_workers(),
1216 HeapRegion::RebuildRSClaimValue);
1217 }
1218 };
1219
1220 class PostCompactionPrinterClosure: public HeapRegionClosure {
1221 private:
1222 G1HRPrinter* _hr_printer;
1223 public:
1224 bool doHeapRegion(HeapRegion* hr) {
1225 assert(!hr->is_young(), "not expecting to find young regions");
1226 // We only generate output for non-empty regions.
1227 if (!hr->is_empty()) {
1228 if (!hr->isHumongous()) {
1229 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1230 } else if (hr->startsHumongous()) {
1231 if (hr->region_num() == 1) {
1232 // single humongous region
1233 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1234 } else {
1235 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1236 }
1237 } else {
1238 assert(hr->continuesHumongous(), "only way to get here");
1239 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1240 }
1241 }
1242 return false;
1243 }
1244
1245 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1246 : _hr_printer(hr_printer) { }
1247 };
1248
1249 void G1CollectedHeap::print_hrs_post_compaction() {
1250 PostCompactionPrinterClosure cl(hr_printer());
1251 heap_region_iterate(&cl);
1252 }
1253
1254 double G1CollectedHeap::verify(bool guard, const char* msg) {
1255 double verify_time_ms = 0.0;
1256
1257 if (guard && total_collections() >= VerifyGCStartAt) {
1258 double verify_start = os::elapsedTime();
1259 HandleMark hm; // Discard invalid handles created during verification
1260 gclog_or_tty->print(msg);
1261 prepare_for_verify();
1262 Universe::verify(false /* silent */, VerifyOption_G1UsePrevMarking);
1263 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
1264 }
1265
1266 return verify_time_ms;
1267 }
1268
1269 void G1CollectedHeap::verify_before_gc() {
1270 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
1271 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
1272 }
1273
1274 void G1CollectedHeap::verify_after_gc() {
1275 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
1276 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
1277 }
1278
1279 bool G1CollectedHeap::do_collection(bool explicit_gc,
1280 bool clear_all_soft_refs,
1281 size_t word_size) {
1282 assert_at_safepoint(true /* should_be_vm_thread */);
1283
1284 if (GC_locker::check_active_before_gc()) {
1285 return false;
1286 }
1287
1288 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1289 gc_timer->register_gc_start(os::elapsed_counter());
1290
1291 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1292 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1293
1294 SvcGCMarker sgcm(SvcGCMarker::FULL);
1295 ResourceMark rm;
1296
1297 print_heap_before_gc();
1298 trace_heap_before_gc(gc_tracer);
1299
1300 HRSPhaseSetter x(HRSPhaseFullGC);
1301 verify_region_sets_optional();
1302
1303 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1304 collector_policy()->should_clear_all_soft_refs();
1305
1306 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1307
1308 {
1309 IsGCActiveMark x;
1310
1311 // Timing
1312 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1313 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1314 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1315
1316 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1317 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1318 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1319
1320 double start = os::elapsedTime();
1321 g1_policy()->record_full_collection_start();
1322
1323 // Note: When we have a more flexible GC logging framework that
1324 // allows us to add optional attributes to a GC log record we
1325 // could consider timing and reporting how long we wait in the
1326 // following two methods.
1327 wait_while_free_regions_coming();
1328 // If we start the compaction before the CM threads finish
1329 // scanning the root regions we might trip them over as we'll
1330 // be moving objects / updating references. So let's wait until
1331 // they are done. By telling them to abort, they should complete
1332 // early.
1333 _cm->root_regions()->abort();
1334 _cm->root_regions()->wait_until_scan_finished();
1335 append_secondary_free_list_if_not_empty_with_lock();
1336
1337 gc_prologue(true);
1338 increment_total_collections(true /* full gc */);
1339 increment_old_marking_cycles_started();
1340
1341 size_t g1h_prev_used = used();
1342 assert(used() == recalculate_used(), "Should be equal");
1343
1344 verify_before_gc();
1345
1346 pre_full_gc_dump(gc_timer);
1347
1348 COMPILER2_PRESENT(DerivedPointerTable::clear());
1349
1350 // Disable discovery and empty the discovered lists
1351 // for the CM ref processor.
1352 ref_processor_cm()->disable_discovery();
1353 ref_processor_cm()->abandon_partial_discovery();
1354 ref_processor_cm()->verify_no_references_recorded();
1355
1356 // Abandon current iterations of concurrent marking and concurrent
1357 // refinement, if any are in progress. We have to do this before
1358 // wait_until_scan_finished() below.
1359 concurrent_mark()->abort();
1360
1361 // Make sure we'll choose a new allocation region afterwards.
1362 release_mutator_alloc_region();
1363 abandon_gc_alloc_regions();
1364 g1_rem_set()->cleanupHRRS();
1365
1366 // We should call this after we retire any currently active alloc
1367 // regions so that all the ALLOC / RETIRE events are generated
1368 // before the start GC event.
1369 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1370
1371 // We may have added regions to the current incremental collection
1372 // set between the last GC or pause and now. We need to clear the
1373 // incremental collection set and then start rebuilding it afresh
1374 // after this full GC.
1375 abandon_collection_set(g1_policy()->inc_cset_head());
1376 g1_policy()->clear_incremental_cset();
1377 g1_policy()->stop_incremental_cset_building();
1378
1379 tear_down_region_sets(false /* free_list_only */);
1380 g1_policy()->set_gcs_are_young(true);
1381
1382 // See the comments in g1CollectedHeap.hpp and
1383 // G1CollectedHeap::ref_processing_init() about
1384 // how reference processing currently works in G1.
1385
1386 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1387 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1388
1389 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1390 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1391
1392 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1393 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1394
1395 // Do collection work
1396 {
1397 HandleMark hm; // Discard invalid handles created during gc
1398 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1399 }
1400
1401 assert(free_regions() == 0, "we should not have added any free regions");
1402 rebuild_region_sets(false /* free_list_only */);
1403
1404 // Enqueue any discovered reference objects that have
1405 // not been removed from the discovered lists.
1406 ref_processor_stw()->enqueue_discovered_references();
1407
1408 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1409
1410 MemoryService::track_memory_usage();
1411
1412 verify_after_gc();
1413
1414 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1415 ref_processor_stw()->verify_no_references_recorded();
1416
1417 // Note: since we've just done a full GC, concurrent
1418 // marking is no longer active. Therefore we need not
1419 // re-enable reference discovery for the CM ref processor.
1420 // That will be done at the start of the next marking cycle.
1421 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1422 ref_processor_cm()->verify_no_references_recorded();
1423
1424 reset_gc_time_stamp();
1425 // Since everything potentially moved, we will clear all remembered
1426 // sets, and clear all cards. Later we will rebuild remembered
1427 // sets. We will also reset the GC time stamps of the regions.
1428 clear_rsets_post_compaction();
1429 check_gc_time_stamps();
1430
1431 // Resize the heap if necessary.
1432 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1433
1434 if (_hr_printer.is_active()) {
1435 // We should do this after we potentially resize the heap so
1436 // that all the COMMIT / UNCOMMIT events are generated before
1437 // the end GC event.
1438
1439 print_hrs_post_compaction();
1440 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1441 }
1442
1443 if (_cg1r->use_cache()) {
1444 _cg1r->clear_and_record_card_counts();
1445 _cg1r->clear_hot_cache();
1446 }
1447
1448 // Rebuild remembered sets of all regions.
1449 if (G1CollectedHeap::use_parallel_gc_threads()) {
1450 uint n_workers =
1451 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1452 workers()->active_workers(),
1453 Threads::number_of_non_daemon_threads());
1454 assert(UseDynamicNumberOfGCThreads ||
1455 n_workers == workers()->total_workers(),
1456 "If not dynamic should be using all the workers");
1457 workers()->set_active_workers(n_workers);
1458 // Set parallel threads in the heap (_n_par_threads) only
1459 // before a parallel phase and always reset it to 0 after
1460 // the phase so that the number of parallel threads does
1461 // no get carried forward to a serial phase where there
1462 // may be code that is "possibly_parallel".
1463 set_par_threads(n_workers);
1464
1465 ParRebuildRSTask rebuild_rs_task(this);
1466 assert(check_heap_region_claim_values(
1467 HeapRegion::InitialClaimValue), "sanity check");
1468 assert(UseDynamicNumberOfGCThreads ||
1469 workers()->active_workers() == workers()->total_workers(),
1470 "Unless dynamic should use total workers");
1471 // Use the most recent number of active workers
1472 assert(workers()->active_workers() > 0,
1473 "Active workers not properly set");
1474 set_par_threads(workers()->active_workers());
1475 workers()->run_task(&rebuild_rs_task);
1476 set_par_threads(0);
1477 assert(check_heap_region_claim_values(
1478 HeapRegion::RebuildRSClaimValue), "sanity check");
1479 reset_heap_region_claim_values();
1480 } else {
1481 RebuildRSOutOfRegionClosure rebuild_rs(this);
1482 heap_region_iterate(&rebuild_rs);
1483 }
1484
1485 if (G1Log::fine()) {
1486 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1487 }
1488
1489 if (true) { // FIXME
1490 // Ask the permanent generation to adjust size for full collections
1491 perm()->compute_new_size();
1492 }
1493
1494 // Start a new incremental collection set for the next pause
1495 assert(g1_policy()->collection_set() == NULL, "must be");
1496 g1_policy()->start_incremental_cset_building();
1497
1498 // Clear the _cset_fast_test bitmap in anticipation of adding
1499 // regions to the incremental collection set for the next
1500 // evacuation pause.
1501 clear_cset_fast_test();
1502
1503 init_mutator_alloc_region();
1504
1505 double end = os::elapsedTime();
1506 g1_policy()->record_full_collection_end();
1507
1508 #ifdef TRACESPINNING
1509 ParallelTaskTerminator::print_termination_counts();
1510 #endif
1511
1512 gc_epilogue(true);
1513
1514 // Discard all rset updates
1515 JavaThread::dirty_card_queue_set().abandon_logs();
1516 assert(!G1DeferredRSUpdate
1517 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1518
1519 _young_list->reset_sampled_info();
1520 // At this point there should be no regions in the
1521 // entire heap tagged as young.
1522 assert( check_young_list_empty(true /* check_heap */),
1523 "young list should be empty at this point");
1524
1525 // Update the number of full collections that have been completed.
1526 increment_old_marking_cycles_completed(false /* concurrent */);
1527
1528 _hrs.verify_optional();
1529 verify_region_sets_optional();
1530
1531 print_heap_after_gc();
1532 trace_heap_after_gc(gc_tracer);
1533
1534 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1535 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1536 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1537 // before any GC notifications are raised.
1538 g1mm()->update_sizes();
1539 }
1540
1541 post_full_gc_dump(gc_timer);
1542
1543 gc_timer->register_gc_end(os::elapsed_counter());
1544
1545 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1546
1547 return true;
1548 }
1549
1550 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1551 // do_collection() will return whether it succeeded in performing
1552 // the GC. Currently, there is no facility on the
1553 // do_full_collection() API to notify the caller than the collection
1554 // did not succeed (e.g., because it was locked out by the GC
1555 // locker). So, right now, we'll ignore the return value.
1556 bool dummy = do_collection(true, /* explicit_gc */
1557 clear_all_soft_refs,
1558 0 /* word_size */);
1559 }
1560
1561 // This code is mostly copied from TenuredGeneration.
1562 void
1563 G1CollectedHeap::
1564 resize_if_necessary_after_full_collection(size_t word_size) {
1565 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1566
1567 // Include the current allocation, if any, and bytes that will be
1568 // pre-allocated to support collections, as "used".
1569 const size_t used_after_gc = used();
1570 const size_t capacity_after_gc = capacity();
1571 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1572
1573 // This is enforced in arguments.cpp.
1574 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1575 "otherwise the code below doesn't make sense");
1576
1577 // We don't have floating point command-line arguments
1578 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1579 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1580 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1581 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1582
1583 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1584 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1585
1586 // We have to be careful here as these two calculations can overflow
1587 // 32-bit size_t's.
1588 double used_after_gc_d = (double) used_after_gc;
1589 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1590 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1591
1592 // Let's make sure that they are both under the max heap size, which
1593 // by default will make them fit into a size_t.
1594 double desired_capacity_upper_bound = (double) max_heap_size;
1595 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1596 desired_capacity_upper_bound);
1597 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1598 desired_capacity_upper_bound);
1599
1600 // We can now safely turn them into size_t's.
1601 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1602 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1603
1604 // This assert only makes sense here, before we adjust them
1605 // with respect to the min and max heap size.
1606 assert(minimum_desired_capacity <= maximum_desired_capacity,
1607 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1608 "maximum_desired_capacity = "SIZE_FORMAT,
1609 minimum_desired_capacity, maximum_desired_capacity));
1610
1611 // Should not be greater than the heap max size. No need to adjust
1612 // it with respect to the heap min size as it's a lower bound (i.e.,
1613 // we'll try to make the capacity larger than it, not smaller).
1614 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1615 // Should not be less than the heap min size. No need to adjust it
1616 // with respect to the heap max size as it's an upper bound (i.e.,
1617 // we'll try to make the capacity smaller than it, not greater).
1618 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1619
1620 if (capacity_after_gc < minimum_desired_capacity) {
1621 // Don't expand unless it's significant
1622 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1623 ergo_verbose4(ErgoHeapSizing,
1624 "attempt heap expansion",
1625 ergo_format_reason("capacity lower than "
1626 "min desired capacity after Full GC")
1627 ergo_format_byte("capacity")
1628 ergo_format_byte("occupancy")
1629 ergo_format_byte_perc("min desired capacity"),
1630 capacity_after_gc, used_after_gc,
1631 minimum_desired_capacity, (double) MinHeapFreeRatio);
1632 expand(expand_bytes);
1633
1634 // No expansion, now see if we want to shrink
1635 } else if (capacity_after_gc > maximum_desired_capacity) {
1636 // Capacity too large, compute shrinking size
1637 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1638 ergo_verbose4(ErgoHeapSizing,
1639 "attempt heap shrinking",
1640 ergo_format_reason("capacity higher than "
1641 "max desired capacity after Full GC")
1642 ergo_format_byte("capacity")
1643 ergo_format_byte("occupancy")
1644 ergo_format_byte_perc("max desired capacity"),
1645 capacity_after_gc, used_after_gc,
1646 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1647 shrink(shrink_bytes);
1648 }
1649 }
1650
1651
1652 HeapWord*
1653 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1654 bool* succeeded) {
1655 assert_at_safepoint(true /* should_be_vm_thread */);
1656
1657 *succeeded = true;
1658 // Let's attempt the allocation first.
1659 HeapWord* result =
1660 attempt_allocation_at_safepoint(word_size,
1661 false /* expect_null_mutator_alloc_region */);
1662 if (result != NULL) {
1663 assert(*succeeded, "sanity");
1664 return result;
1665 }
1666
1667 // In a G1 heap, we're supposed to keep allocation from failing by
1668 // incremental pauses. Therefore, at least for now, we'll favor
1669 // expansion over collection. (This might change in the future if we can
1670 // do something smarter than full collection to satisfy a failed alloc.)
1671 result = expand_and_allocate(word_size);
1672 if (result != NULL) {
1673 assert(*succeeded, "sanity");
1674 return result;
1675 }
1676
1677 // Expansion didn't work, we'll try to do a Full GC.
1678 bool gc_succeeded = do_collection(false, /* explicit_gc */
1679 false, /* clear_all_soft_refs */
1680 word_size);
1681 if (!gc_succeeded) {
1682 *succeeded = false;
1683 return NULL;
1684 }
1685
1686 // Retry the allocation
1687 result = attempt_allocation_at_safepoint(word_size,
1688 true /* expect_null_mutator_alloc_region */);
1689 if (result != NULL) {
1690 assert(*succeeded, "sanity");
1691 return result;
1692 }
1693
1694 // Then, try a Full GC that will collect all soft references.
1695 gc_succeeded = do_collection(false, /* explicit_gc */
1696 true, /* clear_all_soft_refs */
1697 word_size);
1698 if (!gc_succeeded) {
1699 *succeeded = false;
1700 return NULL;
1701 }
1702
1703 // Retry the allocation once more
1704 result = attempt_allocation_at_safepoint(word_size,
1705 true /* expect_null_mutator_alloc_region */);
1706 if (result != NULL) {
1707 assert(*succeeded, "sanity");
1708 return result;
1709 }
1710
1711 assert(!collector_policy()->should_clear_all_soft_refs(),
1712 "Flag should have been handled and cleared prior to this point");
1713
1714 // What else? We might try synchronous finalization later. If the total
1715 // space available is large enough for the allocation, then a more
1716 // complete compaction phase than we've tried so far might be
1717 // appropriate.
1718 assert(*succeeded, "sanity");
1719 return NULL;
1720 }
1721
1722 // Attempting to expand the heap sufficiently
1723 // to support an allocation of the given "word_size". If
1724 // successful, perform the allocation and return the address of the
1725 // allocated block, or else "NULL".
1726
1727 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1728 assert_at_safepoint(true /* should_be_vm_thread */);
1729
1730 verify_region_sets_optional();
1731
1732 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1733 ergo_verbose1(ErgoHeapSizing,
1734 "attempt heap expansion",
1735 ergo_format_reason("allocation request failed")
1736 ergo_format_byte("allocation request"),
1737 word_size * HeapWordSize);
1738 if (expand(expand_bytes)) {
1739 _hrs.verify_optional();
1740 verify_region_sets_optional();
1741 return attempt_allocation_at_safepoint(word_size,
1742 false /* expect_null_mutator_alloc_region */);
1743 }
1744 return NULL;
1745 }
1746
1747 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1748 HeapWord* new_end) {
1749 assert(old_end != new_end, "don't call this otherwise");
1750 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1751
1752 // Update the committed mem region.
1753 _g1_committed.set_end(new_end);
1754 // Tell the card table about the update.
1755 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1756 // Tell the BOT about the update.
1757 _bot_shared->resize(_g1_committed.word_size());
1758 }
1759
1760 bool G1CollectedHeap::expand(size_t expand_bytes) {
1761 size_t old_mem_size = _g1_storage.committed_size();
1762 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1763 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1764 HeapRegion::GrainBytes);
1765 ergo_verbose2(ErgoHeapSizing,
1766 "expand the heap",
1767 ergo_format_byte("requested expansion amount")
1768 ergo_format_byte("attempted expansion amount"),
1769 expand_bytes, aligned_expand_bytes);
1770
1771 // First commit the memory.
1772 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1773 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1774 if (successful) {
1775 // Then propagate this update to the necessary data structures.
1776 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1777 update_committed_space(old_end, new_end);
1778
1779 FreeRegionList expansion_list("Local Expansion List");
1780 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1781 assert(mr.start() == old_end, "post-condition");
1782 // mr might be a smaller region than what was requested if
1783 // expand_by() was unable to allocate the HeapRegion instances
1784 assert(mr.end() <= new_end, "post-condition");
1785
1786 size_t actual_expand_bytes = mr.byte_size();
1787 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1788 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1789 "post-condition");
1790 if (actual_expand_bytes < aligned_expand_bytes) {
1791 // We could not expand _hrs to the desired size. In this case we
1792 // need to shrink the committed space accordingly.
1793 assert(mr.end() < new_end, "invariant");
1794
1795 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1796 // First uncommit the memory.
1797 _g1_storage.shrink_by(diff_bytes);
1798 // Then propagate this update to the necessary data structures.
1799 update_committed_space(new_end, mr.end());
1800 }
1801 _free_list.add_as_tail(&expansion_list);
1802
1803 if (_hr_printer.is_active()) {
1804 HeapWord* curr = mr.start();
1805 while (curr < mr.end()) {
1806 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1807 _hr_printer.commit(curr, curr_end);
1808 curr = curr_end;
1809 }
1810 assert(curr == mr.end(), "post-condition");
1811 }
1812 g1_policy()->record_new_heap_size(n_regions());
1813 } else {
1814 ergo_verbose0(ErgoHeapSizing,
1815 "did not expand the heap",
1816 ergo_format_reason("heap expansion operation failed"));
1817 // The expansion of the virtual storage space was unsuccessful.
1818 // Let's see if it was because we ran out of swap.
1819 if (G1ExitOnExpansionFailure &&
1820 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1821 // We had head room...
1822 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1823 }
1824 }
1825 return successful;
1826 }
1827
1828 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1829 size_t old_mem_size = _g1_storage.committed_size();
1830 size_t aligned_shrink_bytes =
1831 ReservedSpace::page_align_size_down(shrink_bytes);
1832 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1833 HeapRegion::GrainBytes);
1834 uint num_regions_deleted = 0;
1835 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1836 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1837 assert(mr.end() == old_end, "post-condition");
1838
1839 ergo_verbose3(ErgoHeapSizing,
1840 "shrink the heap",
1841 ergo_format_byte("requested shrinking amount")
1842 ergo_format_byte("aligned shrinking amount")
1843 ergo_format_byte("attempted shrinking amount"),
1844 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1845 if (mr.byte_size() > 0) {
1846 if (_hr_printer.is_active()) {
1847 HeapWord* curr = mr.end();
1848 while (curr > mr.start()) {
1849 HeapWord* curr_end = curr;
1850 curr -= HeapRegion::GrainWords;
1851 _hr_printer.uncommit(curr, curr_end);
1852 }
1853 assert(curr == mr.start(), "post-condition");
1854 }
1855
1856 _g1_storage.shrink_by(mr.byte_size());
1857 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1858 assert(mr.start() == new_end, "post-condition");
1859
1860 _expansion_regions += num_regions_deleted;
1861 update_committed_space(old_end, new_end);
1862 HeapRegionRemSet::shrink_heap(n_regions());
1863 g1_policy()->record_new_heap_size(n_regions());
1864 } else {
1865 ergo_verbose0(ErgoHeapSizing,
1866 "did not shrink the heap",
1867 ergo_format_reason("heap shrinking operation failed"));
1868 }
1869 }
1870
1871 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1872 verify_region_sets_optional();
1873
1874 // We should only reach here at the end of a Full GC which means we
1875 // should not not be holding to any GC alloc regions. The method
1876 // below will make sure of that and do any remaining clean up.
1877 abandon_gc_alloc_regions();
1878
1879 // Instead of tearing down / rebuilding the free lists here, we
1880 // could instead use the remove_all_pending() method on free_list to
1881 // remove only the ones that we need to remove.
1882 tear_down_region_sets(true /* free_list_only */);
1883 shrink_helper(shrink_bytes);
1884 rebuild_region_sets(true /* free_list_only */);
1885
1886 _hrs.verify_optional();
1887 verify_region_sets_optional();
1888 }
1889
1890 // Public methods.
1891
1892 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1893 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1894 #endif // _MSC_VER
1895
1896
1897 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1898 SharedHeap(policy_),
1899 _g1_policy(policy_),
1900 _dirty_card_queue_set(false),
1901 _into_cset_dirty_card_queue_set(false),
1902 _is_alive_closure_cm(this),
1903 _is_alive_closure_stw(this),
1904 _ref_processor_cm(NULL),
1905 _ref_processor_stw(NULL),
1906 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1907 _bot_shared(NULL),
1908 _evac_failure_scan_stack(NULL),
1909 _mark_in_progress(false),
1910 _cg1r(NULL), _summary_bytes_used(0),
1911 _g1mm(NULL),
1912 _refine_cte_cl(NULL),
1913 _full_collection(false),
1914 _free_list("Master Free List"),
1915 _secondary_free_list("Secondary Free List"),
1916 _old_set("Old Set"),
1917 _humongous_set("Master Humongous Set"),
1918 _free_regions_coming(false),
1919 _young_list(new YoungList(this)),
1920 _gc_time_stamp(0),
1921 _retained_old_gc_alloc_region(NULL),
1922 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1923 _old_plab_stats(OldPLABSize, PLABWeight),
1924 _expand_heap_after_alloc_failure(true),
1925 _surviving_young_words(NULL),
1926 _old_marking_cycles_started(0),
1927 _old_marking_cycles_completed(0),
1928 _concurrent_cycle_started(false),
1929 _in_cset_fast_test(NULL),
1930 _in_cset_fast_test_base(NULL),
1931 _dirty_cards_region_list(NULL),
1932 _worker_cset_start_region(NULL),
1933 _worker_cset_start_region_time_stamp(NULL),
1934 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1935 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1936 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1937 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1938
1939 _g1h = this;
1940 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1941 vm_exit_during_initialization("Failed necessary allocation.");
1942 }
1943
1944 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1945
1946 int n_queues = MAX2((int)ParallelGCThreads, 1);
1947 _task_queues = new RefToScanQueueSet(n_queues);
1948
1949 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1950 assert(n_rem_sets > 0, "Invariant.");
1951
1952 HeapRegionRemSetIterator** iter_arr = NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues, mtGC);
1953 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1954 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1955 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1956
1957 for (int i = 0; i < n_queues; i++) {
1958 RefToScanQueue* q = new RefToScanQueue();
1959 q->initialize();
1960 _task_queues->register_queue(i, q);
1961 iter_arr[i] = new HeapRegionRemSetIterator();
1962 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1963 }
1964 _rem_set_iterator = iter_arr;
1965
1966 clear_cset_start_regions();
1967
1968 // Initialize the G1EvacuationFailureALot counters and flags.
1969 NOT_PRODUCT(reset_evacuation_should_fail();)
1970
1971 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1972 }
1973
1974 jint G1CollectedHeap::initialize() {
1975 CollectedHeap::pre_initialize();
1976 os::enable_vtime();
1977
1978 G1Log::init();
1979
1980 // Necessary to satisfy locking discipline assertions.
1981
1982 MutexLocker x(Heap_lock);
1983
1984 // We have to initialize the printer before committing the heap, as
1985 // it will be used then.
1986 _hr_printer.set_active(G1PrintHeapRegions);
1987
1988 // While there are no constraints in the GC code that HeapWordSize
1989 // be any particular value, there are multiple other areas in the
1990 // system which believe this to be true (e.g. oop->object_size in some
1991 // cases incorrectly returns the size in wordSize units rather than
1992 // HeapWordSize).
1993 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1994
1995 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1996 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1997
1998 // Ensure that the sizes are properly aligned.
1999 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2000 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2001
2002 _cg1r = new ConcurrentG1Refine();
2003
2004 // Reserve the maximum.
2005 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
2006 // Includes the perm-gen.
2007
2008 // When compressed oops are enabled, the preferred heap base
2009 // is calculated by subtracting the requested size from the
2010 // 32Gb boundary and using the result as the base address for
2011 // heap reservation. If the requested size is not aligned to
2012 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2013 // into the ReservedHeapSpace constructor) then the actual
2014 // base of the reserved heap may end up differing from the
2015 // address that was requested (i.e. the preferred heap base).
2016 // If this happens then we could end up using a non-optimal
2017 // compressed oops mode.
2018
2019 // Since max_byte_size is aligned to the size of a heap region (checked
2020 // above), we also need to align the perm gen size as it might not be.
2021 const size_t total_reserved = max_byte_size +
2022 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
2023 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
2024
2025 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
2026
2027 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
2028 UseLargePages, addr);
2029
2030 if (UseCompressedOops) {
2031 if (addr != NULL && !heap_rs.is_reserved()) {
2032 // Failed to reserve at specified address - the requested memory
2033 // region is taken already, for example, by 'java' launcher.
2034 // Try again to reserver heap higher.
2035 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
2036
2037 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
2038 UseLargePages, addr);
2039
2040 if (addr != NULL && !heap_rs0.is_reserved()) {
2041 // Failed to reserve at specified address again - give up.
2042 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
2043 assert(addr == NULL, "");
2044
2045 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
2046 UseLargePages, addr);
2047 heap_rs = heap_rs1;
2048 } else {
2049 heap_rs = heap_rs0;
2050 }
2051 }
2052 }
2053
2054 if (!heap_rs.is_reserved()) {
2055 vm_exit_during_initialization("Could not reserve enough space for object heap");
2056 return JNI_ENOMEM;
2057 }
2058
2059 // It is important to do this in a way such that concurrent readers can't
2060 // temporarily think something is in the heap. (I've actually seen this
2061 // happen in asserts: DLD.)
2062 _reserved.set_word_size(0);
2063 _reserved.set_start((HeapWord*)heap_rs.base());
2064 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2065
2066 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2067
2068 // Create the gen rem set (and barrier set) for the entire reserved region.
2069 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2070 set_barrier_set(rem_set()->bs());
2071 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2072 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2073 } else {
2074 vm_exit_during_initialization("G1 requires a mod ref bs.");
2075 return JNI_ENOMEM;
2076 }
2077
2078 // Also create a G1 rem set.
2079 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2080 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2081 } else {
2082 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2083 return JNI_ENOMEM;
2084 }
2085
2086 // Carve out the G1 part of the heap.
2087
2088 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2089 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2090 g1_rs.size()/HeapWordSize);
2091 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
2092
2093 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2094
2095 _g1_storage.initialize(g1_rs, 0);
2096 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2097 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2098 (HeapWord*) _g1_reserved.end(),
2099 _expansion_regions);
2100
2101 // 6843694 - ensure that the maximum region index can fit
2102 // in the remembered set structures.
2103 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2104 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2105
2106 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2107 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2108 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2109 "too many cards per region");
2110
2111 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2112
2113 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2114 heap_word_size(init_byte_size));
2115
2116 _g1h = this;
2117
2118 _in_cset_fast_test_length = max_regions();
2119 _in_cset_fast_test_base =
2120 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2121
2122 // We're biasing _in_cset_fast_test to avoid subtracting the
2123 // beginning of the heap every time we want to index; basically
2124 // it's the same with what we do with the card table.
2125 _in_cset_fast_test = _in_cset_fast_test_base -
2126 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2127
2128 // Clear the _cset_fast_test bitmap in anticipation of adding
2129 // regions to the incremental collection set for the first
2130 // evacuation pause.
2131 clear_cset_fast_test();
2132
2133 // Create the ConcurrentMark data structure and thread.
2134 // (Must do this late, so that "max_regions" is defined.)
2135 _cm = new ConcurrentMark(heap_rs, max_regions());
2136 _cmThread = _cm->cmThread();
2137
2138 // Initialize the from_card cache structure of HeapRegionRemSet.
2139 HeapRegionRemSet::init_heap(max_regions());
2140
2141 // Now expand into the initial heap size.
2142 if (!expand(init_byte_size)) {
2143 vm_exit_during_initialization("Failed to allocate initial heap.");
2144 return JNI_ENOMEM;
2145 }
2146
2147 // Perform any initialization actions delegated to the policy.
2148 g1_policy()->init();
2149
2150 _refine_cte_cl =
2151 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2152 g1_rem_set(),
2153 concurrent_g1_refine());
2154 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2155
2156 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2157 SATB_Q_FL_lock,
2158 G1SATBProcessCompletedThreshold,
2159 Shared_SATB_Q_lock);
2160
2161 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2162 DirtyCardQ_FL_lock,
2163 concurrent_g1_refine()->yellow_zone(),
2164 concurrent_g1_refine()->red_zone(),
2165 Shared_DirtyCardQ_lock);
2166
2167 if (G1DeferredRSUpdate) {
2168 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2169 DirtyCardQ_FL_lock,
2170 -1, // never trigger processing
2171 -1, // no limit on length
2172 Shared_DirtyCardQ_lock,
2173 &JavaThread::dirty_card_queue_set());
2174 }
2175
2176 // Initialize the card queue set used to hold cards containing
2177 // references into the collection set.
2178 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2179 DirtyCardQ_FL_lock,
2180 -1, // never trigger processing
2181 -1, // no limit on length
2182 Shared_DirtyCardQ_lock,
2183 &JavaThread::dirty_card_queue_set());
2184
2185 // In case we're keeping closure specialization stats, initialize those
2186 // counts and that mechanism.
2187 SpecializationStats::clear();
2188
2189 // Do later initialization work for concurrent refinement.
2190 _cg1r->init();
2191
2192 // Here we allocate the dummy full region that is required by the
2193 // G1AllocRegion class. If we don't pass an address in the reserved
2194 // space here, lots of asserts fire.
2195
2196 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2197 _g1_reserved.start());
2198 // We'll re-use the same region whether the alloc region will
2199 // require BOT updates or not and, if it doesn't, then a non-young
2200 // region will complain that it cannot support allocations without
2201 // BOT updates. So we'll tag the dummy region as young to avoid that.
2202 dummy_region->set_young();
2203 // Make sure it's full.
2204 dummy_region->set_top(dummy_region->end());
2205 G1AllocRegion::setup(this, dummy_region);
2206
2207 init_mutator_alloc_region();
2208
2209 // Do create of the monitoring and management support so that
2210 // values in the heap have been properly initialized.
2211 _g1mm = new G1MonitoringSupport(this);
2212
2213 return JNI_OK;
2214 }
2215
2216 void G1CollectedHeap::ref_processing_init() {
2217 // Reference processing in G1 currently works as follows:
2218 //
2219 // * There are two reference processor instances. One is
2220 // used to record and process discovered references
2221 // during concurrent marking; the other is used to
2222 // record and process references during STW pauses
2223 // (both full and incremental).
2224 // * Both ref processors need to 'span' the entire heap as
2225 // the regions in the collection set may be dotted around.
2226 //
2227 // * For the concurrent marking ref processor:
2228 // * Reference discovery is enabled at initial marking.
2229 // * Reference discovery is disabled and the discovered
2230 // references processed etc during remarking.
2231 // * Reference discovery is MT (see below).
2232 // * Reference discovery requires a barrier (see below).
2233 // * Reference processing may or may not be MT
2234 // (depending on the value of ParallelRefProcEnabled
2235 // and ParallelGCThreads).
2236 // * A full GC disables reference discovery by the CM
2237 // ref processor and abandons any entries on it's
2238 // discovered lists.
2239 //
2240 // * For the STW processor:
2241 // * Non MT discovery is enabled at the start of a full GC.
2242 // * Processing and enqueueing during a full GC is non-MT.
2243 // * During a full GC, references are processed after marking.
2244 //
2245 // * Discovery (may or may not be MT) is enabled at the start
2246 // of an incremental evacuation pause.
2247 // * References are processed near the end of a STW evacuation pause.
2248 // * For both types of GC:
2249 // * Discovery is atomic - i.e. not concurrent.
2250 // * Reference discovery will not need a barrier.
2251
2252 SharedHeap::ref_processing_init();
2253 MemRegion mr = reserved_region();
2254
2255 // Concurrent Mark ref processor
2256 _ref_processor_cm =
2257 new ReferenceProcessor(mr, // span
2258 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2259 // mt processing
2260 (int) ParallelGCThreads,
2261 // degree of mt processing
2262 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2263 // mt discovery
2264 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2265 // degree of mt discovery
2266 false,
2267 // Reference discovery is not atomic
2268 &_is_alive_closure_cm,
2269 // is alive closure
2270 // (for efficiency/performance)
2271 true);
2272 // Setting next fields of discovered
2273 // lists requires a barrier.
2274
2275 // STW ref processor
2276 _ref_processor_stw =
2277 new ReferenceProcessor(mr, // span
2278 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2279 // mt processing
2280 MAX2((int)ParallelGCThreads, 1),
2281 // degree of mt processing
2282 (ParallelGCThreads > 1),
2283 // mt discovery
2284 MAX2((int)ParallelGCThreads, 1),
2285 // degree of mt discovery
2286 true,
2287 // Reference discovery is atomic
2288 &_is_alive_closure_stw,
2289 // is alive closure
2290 // (for efficiency/performance)
2291 false);
2292 // Setting next fields of discovered
2293 // lists requires a barrier.
2294 }
2295
2296 size_t G1CollectedHeap::capacity() const {
2297 return _g1_committed.byte_size();
2298 }
2299
2300 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2301 assert(!hr->continuesHumongous(), "pre-condition");
2302 hr->reset_gc_time_stamp();
2303 if (hr->startsHumongous()) {
2304 uint first_index = hr->hrs_index() + 1;
2305 uint last_index = hr->last_hc_index();
2306 for (uint i = first_index; i < last_index; i += 1) {
2307 HeapRegion* chr = region_at(i);
2308 assert(chr->continuesHumongous(), "sanity");
2309 chr->reset_gc_time_stamp();
2310 }
2311 }
2312 }
2313
2314 #ifndef PRODUCT
2315 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2316 private:
2317 unsigned _gc_time_stamp;
2318 bool _failures;
2319
2320 public:
2321 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2322 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2323
2324 virtual bool doHeapRegion(HeapRegion* hr) {
2325 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2326 if (_gc_time_stamp != region_gc_time_stamp) {
2327 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2328 "expected %d", HR_FORMAT_PARAMS(hr),
2329 region_gc_time_stamp, _gc_time_stamp);
2330 _failures = true;
2331 }
2332 return false;
2333 }
2334
2335 bool failures() { return _failures; }
2336 };
2337
2338 void G1CollectedHeap::check_gc_time_stamps() {
2339 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2340 heap_region_iterate(&cl);
2341 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2342 }
2343 #endif // PRODUCT
2344
2345 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2346 DirtyCardQueue* into_cset_dcq,
2347 bool concurrent,
2348 int worker_i) {
2349 // Clean cards in the hot card cache
2350 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2351
2352 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2353 int n_completed_buffers = 0;
2354 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2355 n_completed_buffers++;
2356 }
2357 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2358 dcqs.clear_n_completed_buffers();
2359 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2360 }
2361
2362
2363 // Computes the sum of the storage used by the various regions.
2364
2365 size_t G1CollectedHeap::used() const {
2366 assert(Heap_lock->owner() != NULL,
2367 "Should be owned on this thread's behalf.");
2368 size_t result = _summary_bytes_used;
2369 // Read only once in case it is set to NULL concurrently
2370 HeapRegion* hr = _mutator_alloc_region.get();
2371 if (hr != NULL)
2372 result += hr->used();
2373 return result;
2374 }
2375
2376 size_t G1CollectedHeap::used_unlocked() const {
2377 size_t result = _summary_bytes_used;
2378 return result;
2379 }
2380
2381 class SumUsedClosure: public HeapRegionClosure {
2382 size_t _used;
2383 public:
2384 SumUsedClosure() : _used(0) {}
2385 bool doHeapRegion(HeapRegion* r) {
2386 if (!r->continuesHumongous()) {
2387 _used += r->used();
2388 }
2389 return false;
2390 }
2391 size_t result() { return _used; }
2392 };
2393
2394 size_t G1CollectedHeap::recalculate_used() const {
2395 SumUsedClosure blk;
2396 heap_region_iterate(&blk);
2397 return blk.result();
2398 }
2399
2400 size_t G1CollectedHeap::unsafe_max_alloc() {
2401 if (free_regions() > 0) return HeapRegion::GrainBytes;
2402 // otherwise, is there space in the current allocation region?
2403
2404 // We need to store the current allocation region in a local variable
2405 // here. The problem is that this method doesn't take any locks and
2406 // there may be other threads which overwrite the current allocation
2407 // region field. attempt_allocation(), for example, sets it to NULL
2408 // and this can happen *after* the NULL check here but before the call
2409 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2410 // to be a problem in the optimized build, since the two loads of the
2411 // current allocation region field are optimized away.
2412 HeapRegion* hr = _mutator_alloc_region.get();
2413 if (hr == NULL) {
2414 return 0;
2415 }
2416 return hr->free();
2417 }
2418
2419 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2420 switch (cause) {
2421 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2422 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2423 case GCCause::_g1_humongous_allocation: return true;
2424 default: return false;
2425 }
2426 }
2427
2428 #ifndef PRODUCT
2429 void G1CollectedHeap::allocate_dummy_regions() {
2430 // Let's fill up most of the region
2431 size_t word_size = HeapRegion::GrainWords - 1024;
2432 // And as a result the region we'll allocate will be humongous.
2433 guarantee(isHumongous(word_size), "sanity");
2434
2435 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2436 // Let's use the existing mechanism for the allocation
2437 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2438 if (dummy_obj != NULL) {
2439 MemRegion mr(dummy_obj, word_size);
2440 CollectedHeap::fill_with_object(mr);
2441 } else {
2442 // If we can't allocate once, we probably cannot allocate
2443 // again. Let's get out of the loop.
2444 break;
2445 }
2446 }
2447 }
2448 #endif // !PRODUCT
2449
2450 void G1CollectedHeap::increment_old_marking_cycles_started() {
2451 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2452 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2453 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2454 _old_marking_cycles_started, _old_marking_cycles_completed));
2455
2456 _old_marking_cycles_started++;
2457 }
2458
2459 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2460 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2461
2462 // We assume that if concurrent == true, then the caller is a
2463 // concurrent thread that was joined the Suspendible Thread
2464 // Set. If there's ever a cheap way to check this, we should add an
2465 // assert here.
2466
2467 // Given that this method is called at the end of a Full GC or of a
2468 // concurrent cycle, and those can be nested (i.e., a Full GC can
2469 // interrupt a concurrent cycle), the number of full collections
2470 // completed should be either one (in the case where there was no
2471 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2472 // behind the number of full collections started.
2473
2474 // This is the case for the inner caller, i.e. a Full GC.
2475 assert(concurrent ||
2476 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2477 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2478 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2479 "is inconsistent with _old_marking_cycles_completed = %u",
2480 _old_marking_cycles_started, _old_marking_cycles_completed));
2481
2482 // This is the case for the outer caller, i.e. the concurrent cycle.
2483 assert(!concurrent ||
2484 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2485 err_msg("for outer caller (concurrent cycle): "
2486 "_old_marking_cycles_started = %u "
2487 "is inconsistent with _old_marking_cycles_completed = %u",
2488 _old_marking_cycles_started, _old_marking_cycles_completed));
2489
2490 _old_marking_cycles_completed += 1;
2491
2492 // We need to clear the "in_progress" flag in the CM thread before
2493 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2494 // is set) so that if a waiter requests another System.gc() it doesn't
2495 // incorrectly see that a marking cycle is still in progress.
2496 if (concurrent) {
2497 _cmThread->clear_in_progress();
2498 }
2499
2500 // This notify_all() will ensure that a thread that called
2501 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2502 // and it's waiting for a full GC to finish will be woken up. It is
2503 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2504 FullGCCount_lock->notify_all();
2505 }
2506
2507 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2508 _concurrent_cycle_started = true;
2509 _gc_timer_cm->register_gc_start(start_time);
2510
2511 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2512 trace_heap_before_gc(_gc_tracer_cm);
2513 }
2514
2515 void G1CollectedHeap::register_concurrent_cycle_end() {
2516 if (_concurrent_cycle_started) {
2517 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2518
2519 if (_cm->has_aborted()) {
2520 _gc_tracer_cm->report_concurrent_mode_failure();
2521 }
2522 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2523
2524 _concurrent_cycle_started = false;
2525 }
2526 }
2527
2528 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2529 if (_concurrent_cycle_started) {
2530 trace_heap_after_gc(_gc_tracer_cm);
2531 }
2532 }
2533
2534 G1YCType G1CollectedHeap::yc_type() {
2535 bool is_young = g1_policy()->gcs_are_young();
2536 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2537 bool is_during_mark = mark_in_progress();
2538
2539 if (is_initial_mark) {
2540 return InitialMark;
2541 } else if (is_during_mark) {
2542 return DuringMark;
2543 } else if (is_young) {
2544 return Normal;
2545 } else {
2546 return Mixed;
2547 }
2548 }
2549
2550 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2551 assert_at_safepoint(true /* should_be_vm_thread */);
2552 GCCauseSetter gcs(this, cause);
2553 switch (cause) {
2554 case GCCause::_heap_inspection:
2555 case GCCause::_heap_dump: {
2556 HandleMark hm;
2557 do_full_collection(false); // don't clear all soft refs
2558 break;
2559 }
2560 default: // XXX FIX ME
2561 ShouldNotReachHere(); // Unexpected use of this function
2562 }
2563 }
2564
2565 void G1CollectedHeap::collect(GCCause::Cause cause) {
2566 assert_heap_not_locked();
2567
2568 unsigned int gc_count_before;
2569 unsigned int old_marking_count_before;
2570 bool retry_gc;
2571
2572 do {
2573 retry_gc = false;
2574
2575 {
2576 MutexLocker ml(Heap_lock);
2577
2578 // Read the GC count while holding the Heap_lock
2579 gc_count_before = total_collections();
2580 old_marking_count_before = _old_marking_cycles_started;
2581 }
2582
2583 if (should_do_concurrent_full_gc(cause)) {
2584 // Schedule an initial-mark evacuation pause that will start a
2585 // concurrent cycle. We're setting word_size to 0 which means that
2586 // we are not requesting a post-GC allocation.
2587 VM_G1IncCollectionPause op(gc_count_before,
2588 0, /* word_size */
2589 true, /* should_initiate_conc_mark */
2590 g1_policy()->max_pause_time_ms(),
2591 cause);
2592
2593 VMThread::execute(&op);
2594 if (!op.pause_succeeded()) {
2595 if (old_marking_count_before == _old_marking_cycles_started) {
2596 retry_gc = op.should_retry_gc();
2597 } else {
2598 // A Full GC happened while we were trying to schedule the
2599 // initial-mark GC. No point in starting a new cycle given
2600 // that the whole heap was collected anyway.
2601 }
2602
2603 if (retry_gc) {
2604 if (GC_locker::is_active_and_needs_gc()) {
2605 GC_locker::stall_until_clear();
2606 }
2607 }
2608 }
2609 } else {
2610 if (cause == GCCause::_gc_locker
2611 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2612
2613 // Schedule a standard evacuation pause. We're setting word_size
2614 // to 0 which means that we are not requesting a post-GC allocation.
2615 VM_G1IncCollectionPause op(gc_count_before,
2616 0, /* word_size */
2617 false, /* should_initiate_conc_mark */
2618 g1_policy()->max_pause_time_ms(),
2619 cause);
2620 VMThread::execute(&op);
2621 } else {
2622 // Schedule a Full GC.
2623 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2624 VMThread::execute(&op);
2625 }
2626 }
2627 } while (retry_gc);
2628 }
2629
2630 bool G1CollectedHeap::is_in(const void* p) const {
2631 if (_g1_committed.contains(p)) {
2632 // Given that we know that p is in the committed space,
2633 // heap_region_containing_raw() should successfully
2634 // return the containing region.
2635 HeapRegion* hr = heap_region_containing_raw(p);
2636 return hr->is_in(p);
2637 } else {
2638 return _perm_gen->as_gen()->is_in(p);
2639 }
2640 }
2641
2642 // Iteration functions.
2643
2644 // Iterates an OopClosure over all ref-containing fields of objects
2645 // within a HeapRegion.
2646
2647 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2648 MemRegion _mr;
2649 OopClosure* _cl;
2650 public:
2651 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2652 : _mr(mr), _cl(cl) {}
2653 bool doHeapRegion(HeapRegion* r) {
2654 if (!r->continuesHumongous()) {
2655 r->oop_iterate(_cl);
2656 }
2657 return false;
2658 }
2659 };
2660
2661 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2662 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2663 heap_region_iterate(&blk);
2664 if (do_perm) {
2665 perm_gen()->oop_iterate(cl);
2666 }
2667 }
2668
2669 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2670 IterateOopClosureRegionClosure blk(mr, cl);
2671 heap_region_iterate(&blk);
2672 if (do_perm) {
2673 perm_gen()->oop_iterate(cl);
2674 }
2675 }
2676
2677 // Iterates an ObjectClosure over all objects within a HeapRegion.
2678
2679 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2680 ObjectClosure* _cl;
2681 public:
2682 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2683 bool doHeapRegion(HeapRegion* r) {
2684 if (! r->continuesHumongous()) {
2685 r->object_iterate(_cl);
2686 }
2687 return false;
2688 }
2689 };
2690
2691 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2692 IterateObjectClosureRegionClosure blk(cl);
2693 heap_region_iterate(&blk);
2694 if (do_perm) {
2695 perm_gen()->object_iterate(cl);
2696 }
2697 }
2698
2699 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2700 // FIXME: is this right?
2701 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2702 }
2703
2704 // Calls a SpaceClosure on a HeapRegion.
2705
2706 class SpaceClosureRegionClosure: public HeapRegionClosure {
2707 SpaceClosure* _cl;
2708 public:
2709 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2710 bool doHeapRegion(HeapRegion* r) {
2711 _cl->do_space(r);
2712 return false;
2713 }
2714 };
2715
2716 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2717 SpaceClosureRegionClosure blk(cl);
2718 heap_region_iterate(&blk);
2719 }
2720
2721 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2722 _hrs.iterate(cl);
2723 }
2724
2725 void
2726 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2727 uint worker_id,
2728 uint no_of_par_workers,
2729 jint claim_value) {
2730 const uint regions = n_regions();
2731 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2732 no_of_par_workers :
2733 1);
2734 assert(UseDynamicNumberOfGCThreads ||
2735 no_of_par_workers == workers()->total_workers(),
2736 "Non dynamic should use fixed number of workers");
2737 // try to spread out the starting points of the workers
2738 const HeapRegion* start_hr =
2739 start_region_for_worker(worker_id, no_of_par_workers);
2740 const uint start_index = start_hr->hrs_index();
2741
2742 // each worker will actually look at all regions
2743 for (uint count = 0; count < regions; ++count) {
2744 const uint index = (start_index + count) % regions;
2745 assert(0 <= index && index < regions, "sanity");
2746 HeapRegion* r = region_at(index);
2747 // we'll ignore "continues humongous" regions (we'll process them
2748 // when we come across their corresponding "start humongous"
2749 // region) and regions already claimed
2750 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2751 continue;
2752 }
2753 // OK, try to claim it
2754 if (r->claimHeapRegion(claim_value)) {
2755 // success!
2756 assert(!r->continuesHumongous(), "sanity");
2757 if (r->startsHumongous()) {
2758 // If the region is "starts humongous" we'll iterate over its
2759 // "continues humongous" first; in fact we'll do them
2760 // first. The order is important. In on case, calling the
2761 // closure on the "starts humongous" region might de-allocate
2762 // and clear all its "continues humongous" regions and, as a
2763 // result, we might end up processing them twice. So, we'll do
2764 // them first (notice: most closures will ignore them anyway) and
2765 // then we'll do the "starts humongous" region.
2766 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2767 HeapRegion* chr = region_at(ch_index);
2768
2769 // if the region has already been claimed or it's not
2770 // "continues humongous" we're done
2771 if (chr->claim_value() == claim_value ||
2772 !chr->continuesHumongous()) {
2773 break;
2774 }
2775
2776 // Noone should have claimed it directly. We can given
2777 // that we claimed its "starts humongous" region.
2778 assert(chr->claim_value() != claim_value, "sanity");
2779 assert(chr->humongous_start_region() == r, "sanity");
2780
2781 if (chr->claimHeapRegion(claim_value)) {
2782 // we should always be able to claim it; noone else should
2783 // be trying to claim this region
2784
2785 bool res2 = cl->doHeapRegion(chr);
2786 assert(!res2, "Should not abort");
2787
2788 // Right now, this holds (i.e., no closure that actually
2789 // does something with "continues humongous" regions
2790 // clears them). We might have to weaken it in the future,
2791 // but let's leave these two asserts here for extra safety.
2792 assert(chr->continuesHumongous(), "should still be the case");
2793 assert(chr->humongous_start_region() == r, "sanity");
2794 } else {
2795 guarantee(false, "we should not reach here");
2796 }
2797 }
2798 }
2799
2800 assert(!r->continuesHumongous(), "sanity");
2801 bool res = cl->doHeapRegion(r);
2802 assert(!res, "Should not abort");
2803 }
2804 }
2805 }
2806
2807 class ResetClaimValuesClosure: public HeapRegionClosure {
2808 public:
2809 bool doHeapRegion(HeapRegion* r) {
2810 r->set_claim_value(HeapRegion::InitialClaimValue);
2811 return false;
2812 }
2813 };
2814
2815 void G1CollectedHeap::reset_heap_region_claim_values() {
2816 ResetClaimValuesClosure blk;
2817 heap_region_iterate(&blk);
2818 }
2819
2820 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2821 ResetClaimValuesClosure blk;
2822 collection_set_iterate(&blk);
2823 }
2824
2825 #ifdef ASSERT
2826 // This checks whether all regions in the heap have the correct claim
2827 // value. I also piggy-backed on this a check to ensure that the
2828 // humongous_start_region() information on "continues humongous"
2829 // regions is correct.
2830
2831 class CheckClaimValuesClosure : public HeapRegionClosure {
2832 private:
2833 jint _claim_value;
2834 uint _failures;
2835 HeapRegion* _sh_region;
2836
2837 public:
2838 CheckClaimValuesClosure(jint claim_value) :
2839 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2840 bool doHeapRegion(HeapRegion* r) {
2841 if (r->claim_value() != _claim_value) {
2842 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2843 "claim value = %d, should be %d",
2844 HR_FORMAT_PARAMS(r),
2845 r->claim_value(), _claim_value);
2846 ++_failures;
2847 }
2848 if (!r->isHumongous()) {
2849 _sh_region = NULL;
2850 } else if (r->startsHumongous()) {
2851 _sh_region = r;
2852 } else if (r->continuesHumongous()) {
2853 if (r->humongous_start_region() != _sh_region) {
2854 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2855 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2856 HR_FORMAT_PARAMS(r),
2857 r->humongous_start_region(),
2858 _sh_region);
2859 ++_failures;
2860 }
2861 }
2862 return false;
2863 }
2864 uint failures() { return _failures; }
2865 };
2866
2867 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2868 CheckClaimValuesClosure cl(claim_value);
2869 heap_region_iterate(&cl);
2870 return cl.failures() == 0;
2871 }
2872
2873 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2874 private:
2875 jint _claim_value;
2876 uint _failures;
2877
2878 public:
2879 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2880 _claim_value(claim_value), _failures(0) { }
2881
2882 uint failures() { return _failures; }
2883
2884 bool doHeapRegion(HeapRegion* hr) {
2885 assert(hr->in_collection_set(), "how?");
2886 assert(!hr->isHumongous(), "H-region in CSet");
2887 if (hr->claim_value() != _claim_value) {
2888 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2889 "claim value = %d, should be %d",
2890 HR_FORMAT_PARAMS(hr),
2891 hr->claim_value(), _claim_value);
2892 _failures += 1;
2893 }
2894 return false;
2895 }
2896 };
2897
2898 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2899 CheckClaimValuesInCSetHRClosure cl(claim_value);
2900 collection_set_iterate(&cl);
2901 return cl.failures() == 0;
2902 }
2903 #endif // ASSERT
2904
2905 // Clear the cached CSet starting regions and (more importantly)
2906 // the time stamps. Called when we reset the GC time stamp.
2907 void G1CollectedHeap::clear_cset_start_regions() {
2908 assert(_worker_cset_start_region != NULL, "sanity");
2909 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2910
2911 int n_queues = MAX2((int)ParallelGCThreads, 1);
2912 for (int i = 0; i < n_queues; i++) {
2913 _worker_cset_start_region[i] = NULL;
2914 _worker_cset_start_region_time_stamp[i] = 0;
2915 }
2916 }
2917
2918 // Given the id of a worker, obtain or calculate a suitable
2919 // starting region for iterating over the current collection set.
2920 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2921 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2922
2923 HeapRegion* result = NULL;
2924 unsigned gc_time_stamp = get_gc_time_stamp();
2925
2926 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2927 // Cached starting region for current worker was set
2928 // during the current pause - so it's valid.
2929 // Note: the cached starting heap region may be NULL
2930 // (when the collection set is empty).
2931 result = _worker_cset_start_region[worker_i];
2932 assert(result == NULL || result->in_collection_set(), "sanity");
2933 return result;
2934 }
2935
2936 // The cached entry was not valid so let's calculate
2937 // a suitable starting heap region for this worker.
2938
2939 // We want the parallel threads to start their collection
2940 // set iteration at different collection set regions to
2941 // avoid contention.
2942 // If we have:
2943 // n collection set regions
2944 // p threads
2945 // Then thread t will start at region floor ((t * n) / p)
2946
2947 result = g1_policy()->collection_set();
2948 if (G1CollectedHeap::use_parallel_gc_threads()) {
2949 uint cs_size = g1_policy()->cset_region_length();
2950 uint active_workers = workers()->active_workers();
2951 assert(UseDynamicNumberOfGCThreads ||
2952 active_workers == workers()->total_workers(),
2953 "Unless dynamic should use total workers");
2954
2955 uint end_ind = (cs_size * worker_i) / active_workers;
2956 uint start_ind = 0;
2957
2958 if (worker_i > 0 &&
2959 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2960 // Previous workers starting region is valid
2961 // so let's iterate from there
2962 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2963 result = _worker_cset_start_region[worker_i - 1];
2964 }
2965
2966 for (uint i = start_ind; i < end_ind; i++) {
2967 result = result->next_in_collection_set();
2968 }
2969 }
2970
2971 // Note: the calculated starting heap region may be NULL
2972 // (when the collection set is empty).
2973 assert(result == NULL || result->in_collection_set(), "sanity");
2974 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2975 "should be updated only once per pause");
2976 _worker_cset_start_region[worker_i] = result;
2977 OrderAccess::storestore();
2978 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2979 return result;
2980 }
2981
2982 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2983 uint no_of_par_workers) {
2984 uint worker_num =
2985 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2986 assert(UseDynamicNumberOfGCThreads ||
2987 no_of_par_workers == workers()->total_workers(),
2988 "Non dynamic should use fixed number of workers");
2989 const uint start_index = n_regions() * worker_i / worker_num;
2990 return region_at(start_index);
2991 }
2992
2993 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2994 HeapRegion* r = g1_policy()->collection_set();
2995 while (r != NULL) {
2996 HeapRegion* next = r->next_in_collection_set();
2997 if (cl->doHeapRegion(r)) {
2998 cl->incomplete();
2999 return;
3000 }
3001 r = next;
3002 }
3003 }
3004
3005 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
3006 HeapRegionClosure *cl) {
3007 if (r == NULL) {
3008 // The CSet is empty so there's nothing to do.
3009 return;
3010 }
3011
3012 assert(r->in_collection_set(),
3013 "Start region must be a member of the collection set.");
3014 HeapRegion* cur = r;
3015 while (cur != NULL) {
3016 HeapRegion* next = cur->next_in_collection_set();
3017 if (cl->doHeapRegion(cur) && false) {
3018 cl->incomplete();
3019 return;
3020 }
3021 cur = next;
3022 }
3023 cur = g1_policy()->collection_set();
3024 while (cur != r) {
3025 HeapRegion* next = cur->next_in_collection_set();
3026 if (cl->doHeapRegion(cur) && false) {
3027 cl->incomplete();
3028 return;
3029 }
3030 cur = next;
3031 }
3032 }
3033
3034 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
3035 return n_regions() > 0 ? region_at(0) : NULL;
3036 }
3037
3038
3039 Space* G1CollectedHeap::space_containing(const void* addr) const {
3040 Space* res = heap_region_containing(addr);
3041 if (res == NULL)
3042 res = perm_gen()->space_containing(addr);
3043 return res;
3044 }
3045
3046 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
3047 Space* sp = space_containing(addr);
3048 if (sp != NULL) {
3049 return sp->block_start(addr);
3050 }
3051 return NULL;
3052 }
3053
3054 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3055 Space* sp = space_containing(addr);
3056 assert(sp != NULL, "block_size of address outside of heap");
3057 return sp->block_size(addr);
3058 }
3059
3060 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3061 Space* sp = space_containing(addr);
3062 return sp->block_is_obj(addr);
3063 }
3064
3065 bool G1CollectedHeap::supports_tlab_allocation() const {
3066 return true;
3067 }
3068
3069 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3070 return HeapRegion::GrainBytes;
3071 }
3072
3073 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3074 // Return the remaining space in the cur alloc region, but not less than
3075 // the min TLAB size.
3076
3077 // Also, this value can be at most the humongous object threshold,
3078 // since we can't allow tlabs to grow big enough to accommodate
3079 // humongous objects.
3080
3081 HeapRegion* hr = _mutator_alloc_region.get();
3082 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3083 if (hr == NULL) {
3084 return max_tlab_size;
3085 } else {
3086 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3087 }
3088 }
3089
3090 size_t G1CollectedHeap::max_capacity() const {
3091 return _g1_reserved.byte_size();
3092 }
3093
3094 jlong G1CollectedHeap::millis_since_last_gc() {
3095 // assert(false, "NYI");
3096 return 0;
3097 }
3098
3099 void G1CollectedHeap::prepare_for_verify() {
3100 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3101 ensure_parsability(false);
3102 }
3103 g1_rem_set()->prepare_for_verify();
3104 }
3105
3106 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3107 VerifyOption vo) {
3108 switch (vo) {
3109 case VerifyOption_G1UsePrevMarking:
3110 return hr->obj_allocated_since_prev_marking(obj);
3111 case VerifyOption_G1UseNextMarking:
3112 return hr->obj_allocated_since_next_marking(obj);
3113 case VerifyOption_G1UseMarkWord:
3114 return false;
3115 default:
3116 ShouldNotReachHere();
3117 }
3118 return false; // keep some compilers happy
3119 }
3120
3121 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3122 switch (vo) {
3123 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3124 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3125 case VerifyOption_G1UseMarkWord: return NULL;
3126 default: ShouldNotReachHere();
3127 }
3128 return NULL; // keep some compilers happy
3129 }
3130
3131 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3132 switch (vo) {
3133 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3134 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3135 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3136 default: ShouldNotReachHere();
3137 }
3138 return false; // keep some compilers happy
3139 }
3140
3141 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3142 switch (vo) {
3143 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3144 case VerifyOption_G1UseNextMarking: return "NTAMS";
3145 case VerifyOption_G1UseMarkWord: return "NONE";
3146 default: ShouldNotReachHere();
3147 }
3148 return NULL; // keep some compilers happy
3149 }
3150
3151 class VerifyLivenessOopClosure: public OopClosure {
3152 G1CollectedHeap* _g1h;
3153 VerifyOption _vo;
3154 public:
3155 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3156 _g1h(g1h), _vo(vo)
3157 { }
3158 void do_oop(narrowOop *p) { do_oop_work(p); }
3159 void do_oop( oop *p) { do_oop_work(p); }
3160
3161 template <class T> void do_oop_work(T *p) {
3162 oop obj = oopDesc::load_decode_heap_oop(p);
3163 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3164 "Dead object referenced by a not dead object");
3165 }
3166 };
3167
3168 class VerifyObjsInRegionClosure: public ObjectClosure {
3169 private:
3170 G1CollectedHeap* _g1h;
3171 size_t _live_bytes;
3172 HeapRegion *_hr;
3173 VerifyOption _vo;
3174 public:
3175 // _vo == UsePrevMarking -> use "prev" marking information,
3176 // _vo == UseNextMarking -> use "next" marking information,
3177 // _vo == UseMarkWord -> use mark word from object header.
3178 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3179 : _live_bytes(0), _hr(hr), _vo(vo) {
3180 _g1h = G1CollectedHeap::heap();
3181 }
3182 void do_object(oop o) {
3183 VerifyLivenessOopClosure isLive(_g1h, _vo);
3184 assert(o != NULL, "Huh?");
3185 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3186 // If the object is alive according to the mark word,
3187 // then verify that the marking information agrees.
3188 // Note we can't verify the contra-positive of the
3189 // above: if the object is dead (according to the mark
3190 // word), it may not be marked, or may have been marked
3191 // but has since became dead, or may have been allocated
3192 // since the last marking.
3193 if (_vo == VerifyOption_G1UseMarkWord) {
3194 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3195 }
3196
3197 o->oop_iterate(&isLive);
3198 if (!_hr->obj_allocated_since_prev_marking(o)) {
3199 size_t obj_size = o->size(); // Make sure we don't overflow
3200 _live_bytes += (obj_size * HeapWordSize);
3201 }
3202 }
3203 }
3204 size_t live_bytes() { return _live_bytes; }
3205 };
3206
3207 class PrintObjsInRegionClosure : public ObjectClosure {
3208 HeapRegion *_hr;
3209 G1CollectedHeap *_g1;
3210 public:
3211 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3212 _g1 = G1CollectedHeap::heap();
3213 };
3214
3215 void do_object(oop o) {
3216 if (o != NULL) {
3217 HeapWord *start = (HeapWord *) o;
3218 size_t word_sz = o->size();
3219 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3220 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3221 (void*) o, word_sz,
3222 _g1->isMarkedPrev(o),
3223 _g1->isMarkedNext(o),
3224 _hr->obj_allocated_since_prev_marking(o));
3225 HeapWord *end = start + word_sz;
3226 HeapWord *cur;
3227 int *val;
3228 for (cur = start; cur < end; cur++) {
3229 val = (int *) cur;
3230 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3231 }
3232 }
3233 }
3234 };
3235
3236 class VerifyRegionClosure: public HeapRegionClosure {
3237 private:
3238 bool _par;
3239 VerifyOption _vo;
3240 bool _failures;
3241 public:
3242 // _vo == UsePrevMarking -> use "prev" marking information,
3243 // _vo == UseNextMarking -> use "next" marking information,
3244 // _vo == UseMarkWord -> use mark word from object header.
3245 VerifyRegionClosure(bool par, VerifyOption vo)
3246 : _par(par),
3247 _vo(vo),
3248 _failures(false) {}
3249
3250 bool failures() {
3251 return _failures;
3252 }
3253
3254 bool doHeapRegion(HeapRegion* r) {
3255 if (!r->continuesHumongous()) {
3256 bool failures = false;
3257 r->verify(_vo, &failures);
3258 if (failures) {
3259 _failures = true;
3260 } else {
3261 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3262 r->object_iterate(¬_dead_yet_cl);
3263 if (_vo != VerifyOption_G1UseNextMarking) {
3264 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3265 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3266 "max_live_bytes "SIZE_FORMAT" "
3267 "< calculated "SIZE_FORMAT,
3268 r->bottom(), r->end(),
3269 r->max_live_bytes(),
3270 not_dead_yet_cl.live_bytes());
3271 _failures = true;
3272 }
3273 } else {
3274 // When vo == UseNextMarking we cannot currently do a sanity
3275 // check on the live bytes as the calculation has not been
3276 // finalized yet.
3277 }
3278 }
3279 }
3280 return false; // stop the region iteration if we hit a failure
3281 }
3282 };
3283
3284 class VerifyRootsClosure: public OopsInGenClosure {
3285 private:
3286 G1CollectedHeap* _g1h;
3287 VerifyOption _vo;
3288 bool _failures;
3289 public:
3290 // _vo == UsePrevMarking -> use "prev" marking information,
3291 // _vo == UseNextMarking -> use "next" marking information,
3292 // _vo == UseMarkWord -> use mark word from object header.
3293 VerifyRootsClosure(VerifyOption vo) :
3294 _g1h(G1CollectedHeap::heap()),
3295 _vo(vo),
3296 _failures(false) { }
3297
3298 bool failures() { return _failures; }
3299
3300 template <class T> void do_oop_nv(T* p) {
3301 T heap_oop = oopDesc::load_heap_oop(p);
3302 if (!oopDesc::is_null(heap_oop)) {
3303 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3304 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3305 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3306 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3307 if (_vo == VerifyOption_G1UseMarkWord) {
3308 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3309 }
3310 obj->print_on(gclog_or_tty);
3311 _failures = true;
3312 }
3313 }
3314 }
3315
3316 void do_oop(oop* p) { do_oop_nv(p); }
3317 void do_oop(narrowOop* p) { do_oop_nv(p); }
3318 };
3319
3320 // This is the task used for parallel heap verification.
3321
3322 class G1ParVerifyTask: public AbstractGangTask {
3323 private:
3324 G1CollectedHeap* _g1h;
3325 VerifyOption _vo;
3326 bool _failures;
3327
3328 public:
3329 // _vo == UsePrevMarking -> use "prev" marking information,
3330 // _vo == UseNextMarking -> use "next" marking information,
3331 // _vo == UseMarkWord -> use mark word from object header.
3332 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3333 AbstractGangTask("Parallel verify task"),
3334 _g1h(g1h),
3335 _vo(vo),
3336 _failures(false) { }
3337
3338 bool failures() {
3339 return _failures;
3340 }
3341
3342 void work(uint worker_id) {
3343 HandleMark hm;
3344 VerifyRegionClosure blk(true, _vo);
3345 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3346 _g1h->workers()->active_workers(),
3347 HeapRegion::ParVerifyClaimValue);
3348 if (blk.failures()) {
3349 _failures = true;
3350 }
3351 }
3352 };
3353
3354 void G1CollectedHeap::verify(bool silent) {
3355 verify(silent, VerifyOption_G1UsePrevMarking);
3356 }
3357
3358 void G1CollectedHeap::verify(bool silent,
3359 VerifyOption vo) {
3360 if (SafepointSynchronize::is_at_safepoint()) {
3361 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3362 VerifyRootsClosure rootsCl(vo);
3363
3364 assert(Thread::current()->is_VM_thread(),
3365 "Expected to be executed serially by the VM thread at this point");
3366
3367 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3368
3369 // We apply the relevant closures to all the oops in the
3370 // system dictionary, the string table and the code cache.
3371 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3372
3373 process_strong_roots(true, // activate StrongRootsScope
3374 true, // we set "collecting perm gen" to true,
3375 // so we don't reset the dirty cards in the perm gen.
3376 ScanningOption(so), // roots scanning options
3377 &rootsCl,
3378 &blobsCl,
3379 &rootsCl);
3380
3381 // If we're verifying after the marking phase of a Full GC then we can't
3382 // treat the perm gen as roots into the G1 heap. Some of the objects in
3383 // the perm gen may be dead and hence not marked. If one of these dead
3384 // objects is considered to be a root then we may end up with a false
3385 // "Root location <x> points to dead ob <y>" failure.
3386 if (vo != VerifyOption_G1UseMarkWord) {
3387 // Since we used "collecting_perm_gen" == true above, we will not have
3388 // checked the refs from perm into the G1-collected heap. We check those
3389 // references explicitly below. Whether the relevant cards are dirty
3390 // is checked further below in the rem set verification.
3391 if (!silent) { gclog_or_tty->print("Permgen roots "); }
3392 perm_gen()->oop_iterate(&rootsCl);
3393 }
3394 bool failures = rootsCl.failures();
3395
3396 if (vo != VerifyOption_G1UseMarkWord) {
3397 // If we're verifying during a full GC then the region sets
3398 // will have been torn down at the start of the GC. Therefore
3399 // verifying the region sets will fail. So we only verify
3400 // the region sets when not in a full GC.
3401 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3402 verify_region_sets();
3403 }
3404
3405 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3406 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3407 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3408 "sanity check");
3409
3410 G1ParVerifyTask task(this, vo);
3411 assert(UseDynamicNumberOfGCThreads ||
3412 workers()->active_workers() == workers()->total_workers(),
3413 "If not dynamic should be using all the workers");
3414 int n_workers = workers()->active_workers();
3415 set_par_threads(n_workers);
3416 workers()->run_task(&task);
3417 set_par_threads(0);
3418 if (task.failures()) {
3419 failures = true;
3420 }
3421
3422 // Checks that the expected amount of parallel work was done.
3423 // The implication is that n_workers is > 0.
3424 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3425 "sanity check");
3426
3427 reset_heap_region_claim_values();
3428
3429 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3430 "sanity check");
3431 } else {
3432 VerifyRegionClosure blk(false, vo);
3433 heap_region_iterate(&blk);
3434 if (blk.failures()) {
3435 failures = true;
3436 }
3437 }
3438 if (!silent) gclog_or_tty->print("RemSet ");
3439 rem_set()->verify();
3440
3441 if (failures) {
3442 gclog_or_tty->print_cr("Heap:");
3443 // It helps to have the per-region information in the output to
3444 // help us track down what went wrong. This is why we call
3445 // print_extended_on() instead of print_on().
3446 print_extended_on(gclog_or_tty);
3447 gclog_or_tty->print_cr("");
3448 #ifndef PRODUCT
3449 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3450 concurrent_mark()->print_reachable("at-verification-failure",
3451 vo, false /* all */);
3452 }
3453 #endif
3454 gclog_or_tty->flush();
3455 }
3456 guarantee(!failures, "there should not have been any failures");
3457 } else {
3458 if (!silent)
3459 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3460 }
3461 }
3462
3463 class PrintRegionClosure: public HeapRegionClosure {
3464 outputStream* _st;
3465 public:
3466 PrintRegionClosure(outputStream* st) : _st(st) {}
3467 bool doHeapRegion(HeapRegion* r) {
3468 r->print_on(_st);
3469 return false;
3470 }
3471 };
3472
3473 void G1CollectedHeap::print_on(outputStream* st) const {
3474 st->print(" %-20s", "garbage-first heap");
3475 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3476 capacity()/K, used_unlocked()/K);
3477 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3478 _g1_storage.low_boundary(),
3479 _g1_storage.high(),
3480 _g1_storage.high_boundary());
3481 st->cr();
3482 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3483 uint young_regions = _young_list->length();
3484 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3485 (size_t) young_regions * HeapRegion::GrainBytes / K);
3486 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3487 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3488 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3489 st->cr();
3490 perm()->as_gen()->print_on(st);
3491 }
3492
3493 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3494 print_on(st);
3495
3496 // Print the per-region information.
3497 st->cr();
3498 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3499 "HS=humongous(starts), HC=humongous(continues), "
3500 "CS=collection set, F=free, TS=gc time stamp, "
3501 "PTAMS=previous top-at-mark-start, "
3502 "NTAMS=next top-at-mark-start)");
3503 PrintRegionClosure blk(st);
3504 heap_region_iterate(&blk);
3505 }
3506
3507 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3508 if (G1CollectedHeap::use_parallel_gc_threads()) {
3509 workers()->print_worker_threads_on(st);
3510 }
3511 _cmThread->print_on(st);
3512 st->cr();
3513 _cm->print_worker_threads_on(st);
3514 _cg1r->print_worker_threads_on(st);
3515 st->cr();
3516 }
3517
3518 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3519 if (G1CollectedHeap::use_parallel_gc_threads()) {
3520 workers()->threads_do(tc);
3521 }
3522 tc->do_thread(_cmThread);
3523 _cg1r->threads_do(tc);
3524 }
3525
3526 void G1CollectedHeap::print_tracing_info() const {
3527 // We'll overload this to mean "trace GC pause statistics."
3528 if (TraceGen0Time || TraceGen1Time) {
3529 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3530 // to that.
3531 g1_policy()->print_tracing_info();
3532 }
3533 if (G1SummarizeRSetStats) {
3534 g1_rem_set()->print_summary_info();
3535 }
3536 if (G1SummarizeConcMark) {
3537 concurrent_mark()->print_summary_info();
3538 }
3539 g1_policy()->print_yg_surv_rate_info();
3540 SpecializationStats::print();
3541 }
3542
3543 #ifndef PRODUCT
3544 // Helpful for debugging RSet issues.
3545
3546 class PrintRSetsClosure : public HeapRegionClosure {
3547 private:
3548 const char* _msg;
3549 size_t _occupied_sum;
3550
3551 public:
3552 bool doHeapRegion(HeapRegion* r) {
3553 HeapRegionRemSet* hrrs = r->rem_set();
3554 size_t occupied = hrrs->occupied();
3555 _occupied_sum += occupied;
3556
3557 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3558 HR_FORMAT_PARAMS(r));
3559 if (occupied == 0) {
3560 gclog_or_tty->print_cr(" RSet is empty");
3561 } else {
3562 hrrs->print();
3563 }
3564 gclog_or_tty->print_cr("----------");
3565 return false;
3566 }
3567
3568 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3569 gclog_or_tty->cr();
3570 gclog_or_tty->print_cr("========================================");
3571 gclog_or_tty->print_cr(msg);
3572 gclog_or_tty->cr();
3573 }
3574
3575 ~PrintRSetsClosure() {
3576 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3577 gclog_or_tty->print_cr("========================================");
3578 gclog_or_tty->cr();
3579 }
3580 };
3581
3582 void G1CollectedHeap::print_cset_rsets() {
3583 PrintRSetsClosure cl("Printing CSet RSets");
3584 collection_set_iterate(&cl);
3585 }
3586
3587 void G1CollectedHeap::print_all_rsets() {
3588 PrintRSetsClosure cl("Printing All RSets");;
3589 heap_region_iterate(&cl);
3590 }
3591 #endif // PRODUCT
3592
3593 G1CollectedHeap* G1CollectedHeap::heap() {
3594 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3595 "not a garbage-first heap");
3596 return _g1h;
3597 }
3598
3599 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3600 // always_do_update_barrier = false;
3601 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3602 // Call allocation profiler
3603 AllocationProfiler::iterate_since_last_gc();
3604 // Fill TLAB's and such
3605 ensure_parsability(true);
3606 }
3607
3608 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3609 // FIXME: what is this about?
3610 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3611 // is set.
3612 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3613 "derived pointer present"));
3614 // always_do_update_barrier = true;
3615
3616 // We have just completed a GC. Update the soft reference
3617 // policy with the new heap occupancy
3618 Universe::update_heap_info_at_gc();
3619 }
3620
3621 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3622 unsigned int gc_count_before,
3623 bool* succeeded) {
3624 assert_heap_not_locked_and_not_at_safepoint();
3625 g1_policy()->record_stop_world_start();
3626 VM_G1IncCollectionPause op(gc_count_before,
3627 word_size,
3628 false, /* should_initiate_conc_mark */
3629 g1_policy()->max_pause_time_ms(),
3630 GCCause::_g1_inc_collection_pause);
3631 VMThread::execute(&op);
3632
3633 HeapWord* result = op.result();
3634 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3635 assert(result == NULL || ret_succeeded,
3636 "the result should be NULL if the VM did not succeed");
3637 *succeeded = ret_succeeded;
3638
3639 assert_heap_not_locked();
3640 return result;
3641 }
3642
3643 void
3644 G1CollectedHeap::doConcurrentMark() {
3645 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3646 if (!_cmThread->in_progress()) {
3647 _cmThread->set_started();
3648 CGC_lock->notify();
3649 }
3650 }
3651
3652 size_t G1CollectedHeap::pending_card_num() {
3653 size_t extra_cards = 0;
3654 JavaThread *curr = Threads::first();
3655 while (curr != NULL) {
3656 DirtyCardQueue& dcq = curr->dirty_card_queue();
3657 extra_cards += dcq.size();
3658 curr = curr->next();
3659 }
3660 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3661 size_t buffer_size = dcqs.buffer_size();
3662 size_t buffer_num = dcqs.completed_buffers_num();
3663
3664 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3665 // in bytes - not the number of 'entries'. We need to convert
3666 // into a number of cards.
3667 return (buffer_size * buffer_num + extra_cards) / oopSize;
3668 }
3669
3670 size_t G1CollectedHeap::cards_scanned() {
3671 return g1_rem_set()->cardsScanned();
3672 }
3673
3674 void
3675 G1CollectedHeap::setup_surviving_young_words() {
3676 assert(_surviving_young_words == NULL, "pre-condition");
3677 uint array_length = g1_policy()->young_cset_region_length();
3678 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3679 if (_surviving_young_words == NULL) {
3680 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3681 "Not enough space for young surv words summary.");
3682 }
3683 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3684 #ifdef ASSERT
3685 for (uint i = 0; i < array_length; ++i) {
3686 assert( _surviving_young_words[i] == 0, "memset above" );
3687 }
3688 #endif // !ASSERT
3689 }
3690
3691 void
3692 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3693 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3694 uint array_length = g1_policy()->young_cset_region_length();
3695 for (uint i = 0; i < array_length; ++i) {
3696 _surviving_young_words[i] += surv_young_words[i];
3697 }
3698 }
3699
3700 void
3701 G1CollectedHeap::cleanup_surviving_young_words() {
3702 guarantee( _surviving_young_words != NULL, "pre-condition" );
3703 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3704 _surviving_young_words = NULL;
3705 }
3706
3707 #ifdef ASSERT
3708 class VerifyCSetClosure: public HeapRegionClosure {
3709 public:
3710 bool doHeapRegion(HeapRegion* hr) {
3711 // Here we check that the CSet region's RSet is ready for parallel
3712 // iteration. The fields that we'll verify are only manipulated
3713 // when the region is part of a CSet and is collected. Afterwards,
3714 // we reset these fields when we clear the region's RSet (when the
3715 // region is freed) so they are ready when the region is
3716 // re-allocated. The only exception to this is if there's an
3717 // evacuation failure and instead of freeing the region we leave
3718 // it in the heap. In that case, we reset these fields during
3719 // evacuation failure handling.
3720 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3721
3722 // Here's a good place to add any other checks we'd like to
3723 // perform on CSet regions.
3724 return false;
3725 }
3726 };
3727 #endif // ASSERT
3728
3729 #if TASKQUEUE_STATS
3730 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3731 st->print_raw_cr("GC Task Stats");
3732 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3733 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3734 }
3735
3736 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3737 print_taskqueue_stats_hdr(st);
3738
3739 TaskQueueStats totals;
3740 const int n = workers() != NULL ? workers()->total_workers() : 1;
3741 for (int i = 0; i < n; ++i) {
3742 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3743 totals += task_queue(i)->stats;
3744 }
3745 st->print_raw("tot "); totals.print(st); st->cr();
3746
3747 DEBUG_ONLY(totals.verify());
3748 }
3749
3750 void G1CollectedHeap::reset_taskqueue_stats() {
3751 const int n = workers() != NULL ? workers()->total_workers() : 1;
3752 for (int i = 0; i < n; ++i) {
3753 task_queue(i)->stats.reset();
3754 }
3755 }
3756 #endif // TASKQUEUE_STATS
3757
3758 void G1CollectedHeap::log_gc_header() {
3759 if (!G1Log::fine()) {
3760 return;
3761 }
3762
3763 gclog_or_tty->date_stamp(PrintGCDateStamps);
3764 gclog_or_tty->stamp(PrintGCTimeStamps);
3765
3766 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3767 .append(g1_policy()->gcs_are_young() ? " (young)" : " (mixed)")
3768 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3769
3770 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3771 }
3772
3773 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3774 if (!G1Log::fine()) {
3775 return;
3776 }
3777
3778 if (G1Log::finer()) {
3779 if (evacuation_failed()) {
3780 gclog_or_tty->print(" (to-space exhausted)");
3781 }
3782 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3783 g1_policy()->phase_times()->note_gc_end();
3784 g1_policy()->phase_times()->print(pause_time_sec);
3785 g1_policy()->print_detailed_heap_transition();
3786 } else {
3787 if (evacuation_failed()) {
3788 gclog_or_tty->print("--");
3789 }
3790 g1_policy()->print_heap_transition();
3791 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3792 }
3793 gclog_or_tty->flush();
3794 }
3795
3796 bool
3797 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3798 assert_at_safepoint(true /* should_be_vm_thread */);
3799 guarantee(!is_gc_active(), "collection is not reentrant");
3800
3801 if (GC_locker::check_active_before_gc()) {
3802 return false;
3803 }
3804
3805 _gc_timer_stw->register_gc_start(os::elapsed_counter());
3806
3807 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3808
3809 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3810 ResourceMark rm;
3811
3812 print_heap_before_gc();
3813 trace_heap_before_gc(_gc_tracer_stw);
3814
3815 HRSPhaseSetter x(HRSPhaseEvacuation);
3816 verify_region_sets_optional();
3817 verify_dirty_young_regions();
3818
3819 // This call will decide whether this pause is an initial-mark
3820 // pause. If it is, during_initial_mark_pause() will return true
3821 // for the duration of this pause.
3822 g1_policy()->decide_on_conc_mark_initiation();
3823
3824 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3825 assert(!g1_policy()->during_initial_mark_pause() ||
3826 g1_policy()->gcs_are_young(), "sanity");
3827
3828 // We also do not allow mixed GCs during marking.
3829 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3830
3831 // Record whether this pause is an initial mark. When the current
3832 // thread has completed its logging output and it's safe to signal
3833 // the CM thread, the flag's value in the policy has been reset.
3834 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3835
3836 // Inner scope for scope based logging, timers, and stats collection
3837 {
3838 EvacuationInfo evacuation_info;
3839
3840 if (g1_policy()->during_initial_mark_pause()) {
3841 // We are about to start a marking cycle, so we increment the
3842 // full collection counter.
3843 increment_old_marking_cycles_started();
3844 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3845 }
3846
3847 _gc_tracer_stw->report_yc_type(yc_type());
3848
3849 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3850
3851 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3852 workers()->active_workers() : 1);
3853 double pause_start_sec = os::elapsedTime();
3854 g1_policy()->phase_times()->note_gc_start(active_workers);
3855 log_gc_header();
3856
3857 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3858 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3859
3860 // If the secondary_free_list is not empty, append it to the
3861 // free_list. No need to wait for the cleanup operation to finish;
3862 // the region allocation code will check the secondary_free_list
3863 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3864 // set, skip this step so that the region allocation code has to
3865 // get entries from the secondary_free_list.
3866 if (!G1StressConcRegionFreeing) {
3867 append_secondary_free_list_if_not_empty_with_lock();
3868 }
3869
3870 assert(check_young_list_well_formed(),
3871 "young list should be well formed");
3872
3873 // Don't dynamically change the number of GC threads this early. A value of
3874 // 0 is used to indicate serial work. When parallel work is done,
3875 // it will be set.
3876
3877 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3878 IsGCActiveMark x;
3879
3880 gc_prologue(false);
3881 increment_total_collections(false /* full gc */);
3882 increment_gc_time_stamp();
3883
3884 verify_before_gc();
3885
3886 COMPILER2_PRESENT(DerivedPointerTable::clear());
3887
3888 // Please see comment in g1CollectedHeap.hpp and
3889 // G1CollectedHeap::ref_processing_init() to see how
3890 // reference processing currently works in G1.
3891
3892 // Enable discovery in the STW reference processor
3893 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3894 true /*verify_no_refs*/);
3895
3896 {
3897 // We want to temporarily turn off discovery by the
3898 // CM ref processor, if necessary, and turn it back on
3899 // on again later if we do. Using a scoped
3900 // NoRefDiscovery object will do this.
3901 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3902
3903 // Forget the current alloc region (we might even choose it to be part
3904 // of the collection set!).
3905 release_mutator_alloc_region();
3906
3907 // We should call this after we retire the mutator alloc
3908 // region(s) so that all the ALLOC / RETIRE events are generated
3909 // before the start GC event.
3910 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3911
3912 // This timing is only used by the ergonomics to handle our pause target.
3913 // It is unclear why this should not include the full pause. We will
3914 // investigate this in CR 7178365.
3915 //
3916 // Preserving the old comment here if that helps the investigation:
3917 //
3918 // The elapsed time induced by the start time below deliberately elides
3919 // the possible verification above.
3920 double sample_start_time_sec = os::elapsedTime();
3921 size_t start_used_bytes = used();
3922
3923 #if YOUNG_LIST_VERBOSE
3924 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3925 _young_list->print();
3926 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3927 #endif // YOUNG_LIST_VERBOSE
3928
3929 g1_policy()->record_collection_pause_start(sample_start_time_sec,
3930 start_used_bytes);
3931
3932 double scan_wait_start = os::elapsedTime();
3933 // We have to wait until the CM threads finish scanning the
3934 // root regions as it's the only way to ensure that all the
3935 // objects on them have been correctly scanned before we start
3936 // moving them during the GC.
3937 bool waited = _cm->root_regions()->wait_until_scan_finished();
3938 double wait_time_ms = 0.0;
3939 if (waited) {
3940 double scan_wait_end = os::elapsedTime();
3941 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3942 }
3943 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3944
3945 #if YOUNG_LIST_VERBOSE
3946 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3947 _young_list->print();
3948 #endif // YOUNG_LIST_VERBOSE
3949
3950 if (g1_policy()->during_initial_mark_pause()) {
3951 concurrent_mark()->checkpointRootsInitialPre();
3952 }
3953 perm_gen()->save_marks();
3954
3955 #if YOUNG_LIST_VERBOSE
3956 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3957 _young_list->print();
3958 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3959 #endif // YOUNG_LIST_VERBOSE
3960
3961 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3962
3963 _cm->note_start_of_gc();
3964 // We should not verify the per-thread SATB buffers given that
3965 // we have not filtered them yet (we'll do so during the
3966 // GC). We also call this after finalize_cset() to
3967 // ensure that the CSet has been finalized.
3968 _cm->verify_no_cset_oops(true /* verify_stacks */,
3969 true /* verify_enqueued_buffers */,
3970 false /* verify_thread_buffers */,
3971 true /* verify_fingers */);
3972
3973 if (_hr_printer.is_active()) {
3974 HeapRegion* hr = g1_policy()->collection_set();
3975 while (hr != NULL) {
3976 G1HRPrinter::RegionType type;
3977 if (!hr->is_young()) {
3978 type = G1HRPrinter::Old;
3979 } else if (hr->is_survivor()) {
3980 type = G1HRPrinter::Survivor;
3981 } else {
3982 type = G1HRPrinter::Eden;
3983 }
3984 _hr_printer.cset(hr);
3985 hr = hr->next_in_collection_set();
3986 }
3987 }
3988
3989 #ifdef ASSERT
3990 VerifyCSetClosure cl;
3991 collection_set_iterate(&cl);
3992 #endif // ASSERT
3993
3994 setup_surviving_young_words();
3995
3996 // Initialize the GC alloc regions.
3997 init_gc_alloc_regions(evacuation_info);
3998
3999 // Actually do the work...
4000 evacuate_collection_set(evacuation_info);
4001
4002 // We do this to mainly verify the per-thread SATB buffers
4003 // (which have been filtered by now) since we didn't verify
4004 // them earlier. No point in re-checking the stacks / enqueued
4005 // buffers given that the CSet has not changed since last time
4006 // we checked.
4007 _cm->verify_no_cset_oops(false /* verify_stacks */,
4008 false /* verify_enqueued_buffers */,
4009 true /* verify_thread_buffers */,
4010 true /* verify_fingers */);
4011
4012 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4013 g1_policy()->clear_collection_set();
4014
4015 cleanup_surviving_young_words();
4016
4017 // Start a new incremental collection set for the next pause.
4018 g1_policy()->start_incremental_cset_building();
4019
4020 // Clear the _cset_fast_test bitmap in anticipation of adding
4021 // regions to the incremental collection set for the next
4022 // evacuation pause.
4023 clear_cset_fast_test();
4024
4025 _young_list->reset_sampled_info();
4026
4027 // Don't check the whole heap at this point as the
4028 // GC alloc regions from this pause have been tagged
4029 // as survivors and moved on to the survivor list.
4030 // Survivor regions will fail the !is_young() check.
4031 assert(check_young_list_empty(false /* check_heap */),
4032 "young list should be empty");
4033
4034 #if YOUNG_LIST_VERBOSE
4035 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4036 _young_list->print();
4037 #endif // YOUNG_LIST_VERBOSE
4038
4039 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4040 _young_list->first_survivor_region(),
4041 _young_list->last_survivor_region());
4042
4043 _young_list->reset_auxilary_lists();
4044
4045 if (evacuation_failed()) {
4046 _summary_bytes_used = recalculate_used();
4047 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4048 for (uint i = 0; i < n_queues; i++) {
4049 if (_evacuation_failed_info_array[i].has_failed()) {
4050 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4051 }
4052 }
4053 } else {
4054 // The "used" of the the collection set have already been subtracted
4055 // when they were freed. Add in the bytes evacuated.
4056 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4057 }
4058
4059 if (g1_policy()->during_initial_mark_pause()) {
4060 // We have to do this before we notify the CM threads that
4061 // they can start working to make sure that all the
4062 // appropriate initialization is done on the CM object.
4063 concurrent_mark()->checkpointRootsInitialPost();
4064 set_marking_started();
4065 // Note that we don't actually trigger the CM thread at
4066 // this point. We do that later when we're sure that
4067 // the current thread has completed its logging output.
4068 }
4069
4070 allocate_dummy_regions();
4071
4072 #if YOUNG_LIST_VERBOSE
4073 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4074 _young_list->print();
4075 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4076 #endif // YOUNG_LIST_VERBOSE
4077
4078 init_mutator_alloc_region();
4079
4080 {
4081 size_t expand_bytes = g1_policy()->expansion_amount();
4082 if (expand_bytes > 0) {
4083 size_t bytes_before = capacity();
4084 // No need for an ergo verbose message here,
4085 // expansion_amount() does this when it returns a value > 0.
4086 if (!expand(expand_bytes)) {
4087 // We failed to expand the heap so let's verify that
4088 // committed/uncommitted amount match the backing store
4089 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4090 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4091 }
4092 }
4093 }
4094
4095 // We redo the verification but now wrt to the new CSet which
4096 // has just got initialized after the previous CSet was freed.
4097 _cm->verify_no_cset_oops(true /* verify_stacks */,
4098 true /* verify_enqueued_buffers */,
4099 true /* verify_thread_buffers */,
4100 true /* verify_fingers */);
4101 _cm->note_end_of_gc();
4102
4103 // This timing is only used by the ergonomics to handle our pause target.
4104 // It is unclear why this should not include the full pause. We will
4105 // investigate this in CR 7178365.
4106 double sample_end_time_sec = os::elapsedTime();
4107 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4108 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4109
4110 MemoryService::track_memory_usage();
4111
4112 // In prepare_for_verify() below we'll need to scan the deferred
4113 // update buffers to bring the RSets up-to-date if
4114 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4115 // the update buffers we'll probably need to scan cards on the
4116 // regions we just allocated to (i.e., the GC alloc
4117 // regions). However, during the last GC we called
4118 // set_saved_mark() on all the GC alloc regions, so card
4119 // scanning might skip the [saved_mark_word()...top()] area of
4120 // those regions (i.e., the area we allocated objects into
4121 // during the last GC). But it shouldn't. Given that
4122 // saved_mark_word() is conditional on whether the GC time stamp
4123 // on the region is current or not, by incrementing the GC time
4124 // stamp here we invalidate all the GC time stamps on all the
4125 // regions and saved_mark_word() will simply return top() for
4126 // all the regions. This is a nicer way of ensuring this rather
4127 // than iterating over the regions and fixing them. In fact, the
4128 // GC time stamp increment here also ensures that
4129 // saved_mark_word() will return top() between pauses, i.e.,
4130 // during concurrent refinement. So we don't need the
4131 // is_gc_active() check to decided which top to use when
4132 // scanning cards (see CR 7039627).
4133 increment_gc_time_stamp();
4134
4135 verify_after_gc();
4136
4137 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4138 ref_processor_stw()->verify_no_references_recorded();
4139
4140 // CM reference discovery will be re-enabled if necessary.
4141 }
4142
4143 // We should do this after we potentially expand the heap so
4144 // that all the COMMIT events are generated before the end GC
4145 // event, and after we retire the GC alloc regions so that all
4146 // RETIRE events are generated before the end GC event.
4147 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4148
4149 if (mark_in_progress()) {
4150 concurrent_mark()->update_g1_committed();
4151 }
4152
4153 #ifdef TRACESPINNING
4154 ParallelTaskTerminator::print_termination_counts();
4155 #endif
4156
4157 gc_epilogue(false);
4158 }
4159
4160 // Print the remainder of the GC log output.
4161 log_gc_footer(os::elapsedTime() - pause_start_sec);
4162
4163 // It is not yet to safe to tell the concurrent mark to
4164 // start as we have some optional output below. We don't want the
4165 // output from the concurrent mark thread interfering with this
4166 // logging output either.
4167
4168 _hrs.verify_optional();
4169 verify_region_sets_optional();
4170
4171 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4172 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4173
4174 print_heap_after_gc();
4175 trace_heap_after_gc(_gc_tracer_stw);
4176
4177 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4178 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4179 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4180 // before any GC notifications are raised.
4181 g1mm()->update_sizes();
4182
4183 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4184 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4185 _gc_timer_stw->register_gc_end(os::elapsed_counter());
4186 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4187 }
4188
4189 if (G1SummarizeRSetStats &&
4190 (G1SummarizeRSetStatsPeriod > 0) &&
4191 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
4192 g1_rem_set()->print_summary_info();
4193 }
4194 // It should now be safe to tell the concurrent mark thread to start
4195 // without its logging output interfering with the logging output
4196 // that came from the pause.
4197
4198 if (should_start_conc_mark) {
4199 // CAUTION: after the doConcurrentMark() call below,
4200 // the concurrent marking thread(s) could be running
4201 // concurrently with us. Make sure that anything after
4202 // this point does not assume that we are the only GC thread
4203 // running. Note: of course, the actual marking work will
4204 // not start until the safepoint itself is released in
4205 // ConcurrentGCThread::safepoint_desynchronize().
4206 doConcurrentMark();
4207 }
4208
4209 return true;
4210 }
4211
4212 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4213 {
4214 size_t gclab_word_size;
4215 switch (purpose) {
4216 case GCAllocForSurvived:
4217 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4218 break;
4219 case GCAllocForTenured:
4220 gclab_word_size = _old_plab_stats.desired_plab_sz();
4221 break;
4222 default:
4223 assert(false, "unknown GCAllocPurpose");
4224 gclab_word_size = _old_plab_stats.desired_plab_sz();
4225 break;
4226 }
4227
4228 // Prevent humongous PLAB sizes for two reasons:
4229 // * PLABs are allocated using a similar paths as oops, but should
4230 // never be in a humongous region
4231 // * Allowing humongous PLABs needlessly churns the region free lists
4232 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4233 }
4234
4235 void G1CollectedHeap::init_mutator_alloc_region() {
4236 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4237 _mutator_alloc_region.init();
4238 }
4239
4240 void G1CollectedHeap::release_mutator_alloc_region() {
4241 _mutator_alloc_region.release();
4242 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4243 }
4244
4245 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4246 assert_at_safepoint(true /* should_be_vm_thread */);
4247
4248 _survivor_gc_alloc_region.init();
4249 _old_gc_alloc_region.init();
4250 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4251 _retained_old_gc_alloc_region = NULL;
4252
4253 // We will discard the current GC alloc region if:
4254 // a) it's in the collection set (it can happen!),
4255 // b) it's already full (no point in using it),
4256 // c) it's empty (this means that it was emptied during
4257 // a cleanup and it should be on the free list now), or
4258 // d) it's humongous (this means that it was emptied
4259 // during a cleanup and was added to the free list, but
4260 // has been subsequently used to allocate a humongous
4261 // object that may be less than the region size).
4262 if (retained_region != NULL &&
4263 !retained_region->in_collection_set() &&
4264 !(retained_region->top() == retained_region->end()) &&
4265 !retained_region->is_empty() &&
4266 !retained_region->isHumongous()) {
4267 retained_region->set_saved_mark();
4268 // The retained region was added to the old region set when it was
4269 // retired. We have to remove it now, since we don't allow regions
4270 // we allocate to in the region sets. We'll re-add it later, when
4271 // it's retired again.
4272 _old_set.remove(retained_region);
4273 bool during_im = g1_policy()->during_initial_mark_pause();
4274 retained_region->note_start_of_copying(during_im);
4275 _old_gc_alloc_region.set(retained_region);
4276 _hr_printer.reuse(retained_region);
4277 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4278 }
4279 }
4280
4281 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4282 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4283 _old_gc_alloc_region.count());
4284 _survivor_gc_alloc_region.release();
4285 // If we have an old GC alloc region to release, we'll save it in
4286 // _retained_old_gc_alloc_region. If we don't
4287 // _retained_old_gc_alloc_region will become NULL. This is what we
4288 // want either way so no reason to check explicitly for either
4289 // condition.
4290 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4291
4292 if (ResizePLAB) {
4293 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4294 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4295 }
4296 }
4297
4298 void G1CollectedHeap::abandon_gc_alloc_regions() {
4299 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4300 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4301 _retained_old_gc_alloc_region = NULL;
4302 }
4303
4304 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4305 _drain_in_progress = false;
4306 set_evac_failure_closure(cl);
4307 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4308 }
4309
4310 void G1CollectedHeap::finalize_for_evac_failure() {
4311 assert(_evac_failure_scan_stack != NULL &&
4312 _evac_failure_scan_stack->length() == 0,
4313 "Postcondition");
4314 assert(!_drain_in_progress, "Postcondition");
4315 delete _evac_failure_scan_stack;
4316 _evac_failure_scan_stack = NULL;
4317 }
4318
4319 void G1CollectedHeap::remove_self_forwarding_pointers() {
4320 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4321
4322 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4323
4324 if (G1CollectedHeap::use_parallel_gc_threads()) {
4325 set_par_threads();
4326 workers()->run_task(&rsfp_task);
4327 set_par_threads(0);
4328 } else {
4329 rsfp_task.work(0);
4330 }
4331
4332 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4333
4334 // Reset the claim values in the regions in the collection set.
4335 reset_cset_heap_region_claim_values();
4336
4337 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4338
4339 // Now restore saved marks, if any.
4340 assert(_objs_with_preserved_marks.size() ==
4341 _preserved_marks_of_objs.size(), "Both or none.");
4342 while (!_objs_with_preserved_marks.is_empty()) {
4343 oop obj = _objs_with_preserved_marks.pop();
4344 markOop m = _preserved_marks_of_objs.pop();
4345 obj->set_mark(m);
4346 }
4347 _objs_with_preserved_marks.clear(true);
4348 _preserved_marks_of_objs.clear(true);
4349 }
4350
4351 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4352 _evac_failure_scan_stack->push(obj);
4353 }
4354
4355 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4356 assert(_evac_failure_scan_stack != NULL, "precondition");
4357
4358 while (_evac_failure_scan_stack->length() > 0) {
4359 oop obj = _evac_failure_scan_stack->pop();
4360 _evac_failure_closure->set_region(heap_region_containing(obj));
4361 obj->oop_iterate_backwards(_evac_failure_closure);
4362 }
4363 }
4364
4365 oop
4366 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4367 oop old) {
4368 assert(obj_in_cs(old),
4369 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4370 (HeapWord*) old));
4371 markOop m = old->mark();
4372 oop forward_ptr = old->forward_to_atomic(old);
4373 if (forward_ptr == NULL) {
4374 // Forward-to-self succeeded.
4375 assert(_par_scan_state != NULL, "par scan state");
4376 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4377 uint queue_num = _par_scan_state->queue_num();
4378
4379 _evacuation_failed = true;
4380 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4381 if (_evac_failure_closure != cl) {
4382 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4383 assert(!_drain_in_progress,
4384 "Should only be true while someone holds the lock.");
4385 // Set the global evac-failure closure to the current thread's.
4386 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4387 set_evac_failure_closure(cl);
4388 // Now do the common part.
4389 handle_evacuation_failure_common(old, m);
4390 // Reset to NULL.
4391 set_evac_failure_closure(NULL);
4392 } else {
4393 // The lock is already held, and this is recursive.
4394 assert(_drain_in_progress, "This should only be the recursive case.");
4395 handle_evacuation_failure_common(old, m);
4396 }
4397 return old;
4398 } else {
4399 // Forward-to-self failed. Either someone else managed to allocate
4400 // space for this object (old != forward_ptr) or they beat us in
4401 // self-forwarding it (old == forward_ptr).
4402 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4403 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4404 "should not be in the CSet",
4405 (HeapWord*) old, (HeapWord*) forward_ptr));
4406 return forward_ptr;
4407 }
4408 }
4409
4410 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4411 preserve_mark_if_necessary(old, m);
4412
4413 HeapRegion* r = heap_region_containing(old);
4414 if (!r->evacuation_failed()) {
4415 r->set_evacuation_failed(true);
4416 _hr_printer.evac_failure(r);
4417 }
4418
4419 push_on_evac_failure_scan_stack(old);
4420
4421 if (!_drain_in_progress) {
4422 // prevent recursion in copy_to_survivor_space()
4423 _drain_in_progress = true;
4424 drain_evac_failure_scan_stack();
4425 _drain_in_progress = false;
4426 }
4427 }
4428
4429 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4430 assert(evacuation_failed(), "Oversaving!");
4431 // We want to call the "for_promotion_failure" version only in the
4432 // case of a promotion failure.
4433 if (m->must_be_preserved_for_promotion_failure(obj)) {
4434 _objs_with_preserved_marks.push(obj);
4435 _preserved_marks_of_objs.push(m);
4436 }
4437 }
4438
4439 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4440 size_t word_size) {
4441 if (purpose == GCAllocForSurvived) {
4442 HeapWord* result = survivor_attempt_allocation(word_size);
4443 if (result != NULL) {
4444 return result;
4445 } else {
4446 // Let's try to allocate in the old gen in case we can fit the
4447 // object there.
4448 return old_attempt_allocation(word_size);
4449 }
4450 } else {
4451 assert(purpose == GCAllocForTenured, "sanity");
4452 HeapWord* result = old_attempt_allocation(word_size);
4453 if (result != NULL) {
4454 return result;
4455 } else {
4456 // Let's try to allocate in the survivors in case we can fit the
4457 // object there.
4458 return survivor_attempt_allocation(word_size);
4459 }
4460 }
4461
4462 ShouldNotReachHere();
4463 // Trying to keep some compilers happy.
4464 return NULL;
4465 }
4466
4467 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4468 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4469
4470 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4471 : _g1h(g1h),
4472 _refs(g1h->task_queue(queue_num)),
4473 _dcq(&g1h->dirty_card_queue_set()),
4474 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4475 _g1_rem(g1h->g1_rem_set()),
4476 _hash_seed(17), _queue_num(queue_num),
4477 _term_attempts(0),
4478 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4479 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4480 _age_table(false),
4481 _strong_roots_time(0), _term_time(0),
4482 _alloc_buffer_waste(0), _undo_waste(0) {
4483 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4484 // we "sacrifice" entry 0 to keep track of surviving bytes for
4485 // non-young regions (where the age is -1)
4486 // We also add a few elements at the beginning and at the end in
4487 // an attempt to eliminate cache contention
4488 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4489 uint array_length = PADDING_ELEM_NUM +
4490 real_length +
4491 PADDING_ELEM_NUM;
4492 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4493 if (_surviving_young_words_base == NULL)
4494 vm_exit_out_of_memory(array_length * sizeof(size_t),
4495 "Not enough space for young surv histo.");
4496 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4497 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4498
4499 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4500 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4501
4502 _start = os::elapsedTime();
4503 }
4504
4505 void
4506 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4507 {
4508 st->print_raw_cr("GC Termination Stats");
4509 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4510 " ------waste (KiB)------");
4511 st->print_raw_cr("thr ms ms % ms % attempts"
4512 " total alloc undo");
4513 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4514 " ------- ------- -------");
4515 }
4516
4517 void
4518 G1ParScanThreadState::print_termination_stats(int i,
4519 outputStream* const st) const
4520 {
4521 const double elapsed_ms = elapsed_time() * 1000.0;
4522 const double s_roots_ms = strong_roots_time() * 1000.0;
4523 const double term_ms = term_time() * 1000.0;
4524 st->print_cr("%3d %9.2f %9.2f %6.2f "
4525 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4526 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4527 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4528 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4529 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4530 alloc_buffer_waste() * HeapWordSize / K,
4531 undo_waste() * HeapWordSize / K);
4532 }
4533
4534 #ifdef ASSERT
4535 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4536 assert(ref != NULL, "invariant");
4537 assert(UseCompressedOops, "sanity");
4538 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4539 oop p = oopDesc::load_decode_heap_oop(ref);
4540 assert(_g1h->is_in_g1_reserved(p),
4541 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4542 return true;
4543 }
4544
4545 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4546 assert(ref != NULL, "invariant");
4547 if (has_partial_array_mask(ref)) {
4548 // Must be in the collection set--it's already been copied.
4549 oop p = clear_partial_array_mask(ref);
4550 assert(_g1h->obj_in_cs(p),
4551 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4552 } else {
4553 oop p = oopDesc::load_decode_heap_oop(ref);
4554 assert(_g1h->is_in_g1_reserved(p),
4555 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4556 }
4557 return true;
4558 }
4559
4560 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4561 if (ref.is_narrow()) {
4562 return verify_ref((narrowOop*) ref);
4563 } else {
4564 return verify_ref((oop*) ref);
4565 }
4566 }
4567 #endif // ASSERT
4568
4569 void G1ParScanThreadState::trim_queue() {
4570 assert(_evac_cl != NULL, "not set");
4571 assert(_evac_failure_cl != NULL, "not set");
4572 assert(_partial_scan_cl != NULL, "not set");
4573
4574 StarTask ref;
4575 do {
4576 // Drain the overflow stack first, so other threads can steal.
4577 while (refs()->pop_overflow(ref)) {
4578 deal_with_reference(ref);
4579 }
4580
4581 while (refs()->pop_local(ref)) {
4582 deal_with_reference(ref);
4583 }
4584 } while (!refs()->is_empty());
4585 }
4586
4587 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4588 G1ParScanThreadState* par_scan_state) :
4589 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4590 _par_scan_state(par_scan_state),
4591 _worker_id(par_scan_state->queue_num()),
4592 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4593 _mark_in_progress(_g1->mark_in_progress()) { }
4594
4595 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4596 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4597 #ifdef ASSERT
4598 HeapRegion* hr = _g1->heap_region_containing(obj);
4599 assert(hr != NULL, "sanity");
4600 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4601 #endif // ASSERT
4602
4603 // We know that the object is not moving so it's safe to read its size.
4604 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4605 }
4606
4607 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4608 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4609 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4610 #ifdef ASSERT
4611 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4612 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4613 assert(from_obj != to_obj, "should not be self-forwarded");
4614
4615 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4616 assert(from_hr != NULL, "sanity");
4617 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4618
4619 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4620 assert(to_hr != NULL, "sanity");
4621 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4622 #endif // ASSERT
4623
4624 // The object might be in the process of being copied by another
4625 // worker so we cannot trust that its to-space image is
4626 // well-formed. So we have to read its size from its from-space
4627 // image which we know should not be changing.
4628 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4629 }
4630
4631 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4632 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4633 ::copy_to_survivor_space(oop old) {
4634 size_t word_sz = old->size();
4635 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4636 // +1 to make the -1 indexes valid...
4637 int young_index = from_region->young_index_in_cset()+1;
4638 assert( (from_region->is_young() && young_index > 0) ||
4639 (!from_region->is_young() && young_index == 0), "invariant" );
4640 G1CollectorPolicy* g1p = _g1->g1_policy();
4641 markOop m = old->mark();
4642 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4643 : m->age();
4644 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4645 word_sz);
4646 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4647 #ifndef PRODUCT
4648 // Should this evacuation fail?
4649 if (_g1->evacuation_should_fail()) {
4650 if (obj_ptr != NULL) {
4651 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4652 obj_ptr = NULL;
4653 }
4654 }
4655 #endif // !PRODUCT
4656
4657 if (obj_ptr == NULL) {
4658 // This will either forward-to-self, or detect that someone else has
4659 // installed a forwarding pointer.
4660 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4661 }
4662
4663 oop obj = oop(obj_ptr);
4664
4665 // We're going to allocate linearly, so might as well prefetch ahead.
4666 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4667
4668 oop forward_ptr = old->forward_to_atomic(obj);
4669 if (forward_ptr == NULL) {
4670 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4671 if (g1p->track_object_age(alloc_purpose)) {
4672 // We could simply do obj->incr_age(). However, this causes a
4673 // performance issue. obj->incr_age() will first check whether
4674 // the object has a displaced mark by checking its mark word;
4675 // getting the mark word from the new location of the object
4676 // stalls. So, given that we already have the mark word and we
4677 // are about to install it anyway, it's better to increase the
4678 // age on the mark word, when the object does not have a
4679 // displaced mark word. We're not expecting many objects to have
4680 // a displaced marked word, so that case is not optimized
4681 // further (it could be...) and we simply call obj->incr_age().
4682
4683 if (m->has_displaced_mark_helper()) {
4684 // in this case, we have to install the mark word first,
4685 // otherwise obj looks to be forwarded (the old mark word,
4686 // which contains the forward pointer, was copied)
4687 obj->set_mark(m);
4688 obj->incr_age();
4689 } else {
4690 m = m->incr_age();
4691 obj->set_mark(m);
4692 }
4693 _par_scan_state->age_table()->add(obj, word_sz);
4694 } else {
4695 obj->set_mark(m);
4696 }
4697
4698 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4699 surv_young_words[young_index] += word_sz;
4700
4701 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4702 // We keep track of the next start index in the length field of
4703 // the to-space object. The actual length can be found in the
4704 // length field of the from-space object.
4705 arrayOop(obj)->set_length(0);
4706 oop* old_p = set_partial_array_mask(old);
4707 _par_scan_state->push_on_queue(old_p);
4708 } else {
4709 // No point in using the slower heap_region_containing() method,
4710 // given that we know obj is in the heap.
4711 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4712 obj->oop_iterate_backwards(&_scanner);
4713 }
4714 } else {
4715 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4716 obj = forward_ptr;
4717 }
4718 return obj;
4719 }
4720
4721 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4722 template <class T>
4723 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4724 ::do_oop_work(T* p) {
4725 oop obj = oopDesc::load_decode_heap_oop(p);
4726 assert(barrier != G1BarrierRS || obj != NULL,
4727 "Precondition: G1BarrierRS implies obj is non-NULL");
4728
4729 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4730
4731 // here the null check is implicit in the cset_fast_test() test
4732 if (_g1->in_cset_fast_test(obj)) {
4733 oop forwardee;
4734 if (obj->is_forwarded()) {
4735 forwardee = obj->forwardee();
4736 } else {
4737 forwardee = copy_to_survivor_space(obj);
4738 }
4739 assert(forwardee != NULL, "forwardee should not be NULL");
4740 oopDesc::encode_store_heap_oop(p, forwardee);
4741 if (do_mark_object && forwardee != obj) {
4742 // If the object is self-forwarded we don't need to explicitly
4743 // mark it, the evacuation failure protocol will do so.
4744 mark_forwarded_object(obj, forwardee);
4745 }
4746
4747 // When scanning the RS, we only care about objs in CS.
4748 if (barrier == G1BarrierRS) {
4749 _par_scan_state->update_rs(_from, p, _worker_id);
4750 }
4751 } else {
4752 // The object is not in collection set. If we're a root scanning
4753 // closure during an initial mark pause (i.e. do_mark_object will
4754 // be true) then attempt to mark the object.
4755 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4756 mark_object(obj);
4757 }
4758 }
4759
4760 if (barrier == G1BarrierEvac && obj != NULL) {
4761 _par_scan_state->update_rs(_from, p, _worker_id);
4762 }
4763
4764 if (do_gen_barrier && obj != NULL) {
4765 par_do_barrier(p);
4766 }
4767 }
4768
4769 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4770 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4771
4772 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4773 assert(has_partial_array_mask(p), "invariant");
4774 oop from_obj = clear_partial_array_mask(p);
4775
4776 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4777 assert(from_obj->is_objArray(), "must be obj array");
4778 objArrayOop from_obj_array = objArrayOop(from_obj);
4779 // The from-space object contains the real length.
4780 int length = from_obj_array->length();
4781
4782 assert(from_obj->is_forwarded(), "must be forwarded");
4783 oop to_obj = from_obj->forwardee();
4784 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4785 objArrayOop to_obj_array = objArrayOop(to_obj);
4786 // We keep track of the next start index in the length field of the
4787 // to-space object.
4788 int next_index = to_obj_array->length();
4789 assert(0 <= next_index && next_index < length,
4790 err_msg("invariant, next index: %d, length: %d", next_index, length));
4791
4792 int start = next_index;
4793 int end = length;
4794 int remainder = end - start;
4795 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4796 if (remainder > 2 * ParGCArrayScanChunk) {
4797 end = start + ParGCArrayScanChunk;
4798 to_obj_array->set_length(end);
4799 // Push the remainder before we process the range in case another
4800 // worker has run out of things to do and can steal it.
4801 oop* from_obj_p = set_partial_array_mask(from_obj);
4802 _par_scan_state->push_on_queue(from_obj_p);
4803 } else {
4804 assert(length == end, "sanity");
4805 // We'll process the final range for this object. Restore the length
4806 // so that the heap remains parsable in case of evacuation failure.
4807 to_obj_array->set_length(end);
4808 }
4809 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4810 // Process indexes [start,end). It will also process the header
4811 // along with the first chunk (i.e., the chunk with start == 0).
4812 // Note that at this point the length field of to_obj_array is not
4813 // correct given that we are using it to keep track of the next
4814 // start index. oop_iterate_range() (thankfully!) ignores the length
4815 // field and only relies on the start / end parameters. It does
4816 // however return the size of the object which will be incorrect. So
4817 // we have to ignore it even if we wanted to use it.
4818 to_obj_array->oop_iterate_range(&_scanner, start, end);
4819 }
4820
4821 class G1ParEvacuateFollowersClosure : public VoidClosure {
4822 protected:
4823 G1CollectedHeap* _g1h;
4824 G1ParScanThreadState* _par_scan_state;
4825 RefToScanQueueSet* _queues;
4826 ParallelTaskTerminator* _terminator;
4827
4828 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4829 RefToScanQueueSet* queues() { return _queues; }
4830 ParallelTaskTerminator* terminator() { return _terminator; }
4831
4832 public:
4833 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4834 G1ParScanThreadState* par_scan_state,
4835 RefToScanQueueSet* queues,
4836 ParallelTaskTerminator* terminator)
4837 : _g1h(g1h), _par_scan_state(par_scan_state),
4838 _queues(queues), _terminator(terminator) {}
4839
4840 void do_void();
4841
4842 private:
4843 inline bool offer_termination();
4844 };
4845
4846 bool G1ParEvacuateFollowersClosure::offer_termination() {
4847 G1ParScanThreadState* const pss = par_scan_state();
4848 pss->start_term_time();
4849 const bool res = terminator()->offer_termination();
4850 pss->end_term_time();
4851 return res;
4852 }
4853
4854 void G1ParEvacuateFollowersClosure::do_void() {
4855 StarTask stolen_task;
4856 G1ParScanThreadState* const pss = par_scan_state();
4857 pss->trim_queue();
4858
4859 do {
4860 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4861 assert(pss->verify_task(stolen_task), "sanity");
4862 if (stolen_task.is_narrow()) {
4863 pss->deal_with_reference((narrowOop*) stolen_task);
4864 } else {
4865 pss->deal_with_reference((oop*) stolen_task);
4866 }
4867
4868 // We've just processed a reference and we might have made
4869 // available new entries on the queues. So we have to make sure
4870 // we drain the queues as necessary.
4871 pss->trim_queue();
4872 }
4873 } while (!offer_termination());
4874
4875 pss->retire_alloc_buffers();
4876 }
4877
4878 class G1ParTask : public AbstractGangTask {
4879 protected:
4880 G1CollectedHeap* _g1h;
4881 RefToScanQueueSet *_queues;
4882 ParallelTaskTerminator _terminator;
4883 uint _n_workers;
4884
4885 Mutex _stats_lock;
4886 Mutex* stats_lock() { return &_stats_lock; }
4887
4888 size_t getNCards() {
4889 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4890 / G1BlockOffsetSharedArray::N_bytes;
4891 }
4892
4893 public:
4894 G1ParTask(G1CollectedHeap* g1h,
4895 RefToScanQueueSet *task_queues)
4896 : AbstractGangTask("G1 collection"),
4897 _g1h(g1h),
4898 _queues(task_queues),
4899 _terminator(0, _queues),
4900 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4901 {}
4902
4903 RefToScanQueueSet* queues() { return _queues; }
4904
4905 RefToScanQueue *work_queue(int i) {
4906 return queues()->queue(i);
4907 }
4908
4909 ParallelTaskTerminator* terminator() { return &_terminator; }
4910
4911 virtual void set_for_termination(int active_workers) {
4912 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4913 // in the young space (_par_seq_tasks) in the G1 heap
4914 // for SequentialSubTasksDone.
4915 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4916 // both of which need setting by set_n_termination().
4917 _g1h->SharedHeap::set_n_termination(active_workers);
4918 _g1h->set_n_termination(active_workers);
4919 terminator()->reset_for_reuse(active_workers);
4920 _n_workers = active_workers;
4921 }
4922
4923 void work(uint worker_id) {
4924 if (worker_id >= _n_workers) return; // no work needed this round
4925
4926 double start_time_ms = os::elapsedTime() * 1000.0;
4927 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4928
4929 {
4930 ResourceMark rm;
4931 HandleMark hm;
4932
4933 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4934
4935 G1ParScanThreadState pss(_g1h, worker_id);
4936 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4937 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4938 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4939
4940 pss.set_evac_closure(&scan_evac_cl);
4941 pss.set_evac_failure_closure(&evac_failure_cl);
4942 pss.set_partial_scan_closure(&partial_scan_cl);
4943
4944 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4945 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp);
4946
4947 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4948 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp);
4949
4950 OopClosure* scan_root_cl = &only_scan_root_cl;
4951 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl;
4952
4953 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4954 // We also need to mark copied objects.
4955 scan_root_cl = &scan_mark_root_cl;
4956 scan_perm_cl = &scan_mark_perm_cl;
4957 }
4958
4959 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4960
4961 pss.start_strong_roots();
4962 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4963 SharedHeap::SO_AllClasses,
4964 scan_root_cl,
4965 &push_heap_rs_cl,
4966 scan_perm_cl,
4967 worker_id);
4968 pss.end_strong_roots();
4969
4970 {
4971 double start = os::elapsedTime();
4972 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4973 evac.do_void();
4974 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4975 double term_ms = pss.term_time()*1000.0;
4976 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4977 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4978 }
4979 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4980 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4981
4982 if (ParallelGCVerbose) {
4983 MutexLocker x(stats_lock());
4984 pss.print_termination_stats(worker_id);
4985 }
4986
4987 assert(pss.refs()->is_empty(), "should be empty");
4988
4989 // Close the inner scope so that the ResourceMark and HandleMark
4990 // destructors are executed here and are included as part of the
4991 // "GC Worker Time".
4992 }
4993
4994 double end_time_ms = os::elapsedTime() * 1000.0;
4995 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4996 }
4997 };
4998
4999 // *** Common G1 Evacuation Stuff
5000
5001 // Closures that support the filtering of CodeBlobs scanned during
5002 // external root scanning.
5003
5004 // Closure applied to reference fields in code blobs (specifically nmethods)
5005 // to determine whether an nmethod contains references that point into
5006 // the collection set. Used as a predicate when walking code roots so
5007 // that only nmethods that point into the collection set are added to the
5008 // 'marked' list.
5009
5010 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
5011
5012 class G1PointsIntoCSOopClosure : public OopClosure {
5013 G1CollectedHeap* _g1;
5014 bool _points_into_cs;
5015 public:
5016 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
5017 _g1(g1), _points_into_cs(false) { }
5018
5019 bool points_into_cs() const { return _points_into_cs; }
5020
5021 template <class T>
5022 void do_oop_nv(T* p) {
5023 if (!_points_into_cs) {
5024 T heap_oop = oopDesc::load_heap_oop(p);
5025 if (!oopDesc::is_null(heap_oop) &&
5026 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
5027 _points_into_cs = true;
5028 }
5029 }
5030 }
5031
5032 virtual void do_oop(oop* p) { do_oop_nv(p); }
5033 virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
5034 };
5035
5036 G1CollectedHeap* _g1;
5037
5038 public:
5039 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
5040 CodeBlobToOopClosure(cl, true), _g1(g1) { }
5041
5042 virtual void do_code_blob(CodeBlob* cb) {
5043 nmethod* nm = cb->as_nmethod_or_null();
5044 if (nm != NULL && !(nm->test_oops_do_mark())) {
5045 G1PointsIntoCSOopClosure predicate_cl(_g1);
5046 nm->oops_do(&predicate_cl);
5047
5048 if (predicate_cl.points_into_cs()) {
5049 // At least one of the reference fields or the oop relocations
5050 // in the nmethod points into the collection set. We have to
5051 // 'mark' this nmethod.
5052 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
5053 // or MarkingCodeBlobClosure::do_code_blob() change.
5054 if (!nm->test_set_oops_do_mark()) {
5055 do_newly_marked_nmethod(nm);
5056 }
5057 }
5058 }
5059 }
5060 };
5061
5062 // This method is run in a GC worker.
5063
5064 void
5065 G1CollectedHeap::
5066 g1_process_strong_roots(bool collecting_perm_gen,
5067 ScanningOption so,
5068 OopClosure* scan_non_heap_roots,
5069 OopsInHeapRegionClosure* scan_rs,
5070 OopsInGenClosure* scan_perm,
5071 int worker_i) {
5072
5073 // First scan the strong roots, including the perm gen.
5074 double ext_roots_start = os::elapsedTime();
5075 double closure_app_time_sec = 0.0;
5076
5077 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5078 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
5079 buf_scan_perm.set_generation(perm_gen());
5080
5081 // Walk the code cache w/o buffering, because StarTask cannot handle
5082 // unaligned oop locations.
5083 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5084
5085 process_strong_roots(false, // no scoping; this is parallel code
5086 collecting_perm_gen, so,
5087 &buf_scan_non_heap_roots,
5088 &eager_scan_code_roots,
5089 &buf_scan_perm);
5090
5091 // Now the CM ref_processor roots.
5092 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5093 // We need to treat the discovered reference lists of the
5094 // concurrent mark ref processor as roots and keep entries
5095 // (which are added by the marking threads) on them live
5096 // until they can be processed at the end of marking.
5097 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5098 }
5099
5100 // Finish up any enqueued closure apps (attributed as object copy time).
5101 buf_scan_non_heap_roots.done();
5102 buf_scan_perm.done();
5103
5104 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
5105 buf_scan_non_heap_roots.closure_app_seconds();
5106 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5107
5108 double ext_root_time_ms =
5109 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5110
5111 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5112
5113 // During conc marking we have to filter the per-thread SATB buffers
5114 // to make sure we remove any oops into the CSet (which will show up
5115 // as implicitly live).
5116 double satb_filtering_ms = 0.0;
5117 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5118 if (mark_in_progress()) {
5119 double satb_filter_start = os::elapsedTime();
5120
5121 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5122
5123 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5124 }
5125 }
5126 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5127
5128 // Now scan the complement of the collection set.
5129 if (scan_rs != NULL) {
5130 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5131 }
5132
5133 _process_strong_tasks->all_tasks_completed();
5134 }
5135
5136 void
5137 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
5138 OopClosure* non_root_closure) {
5139 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5140 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
5141 }
5142
5143 // Weak Reference Processing support
5144
5145 // An always "is_alive" closure that is used to preserve referents.
5146 // If the object is non-null then it's alive. Used in the preservation
5147 // of referent objects that are pointed to by reference objects
5148 // discovered by the CM ref processor.
5149 class G1AlwaysAliveClosure: public BoolObjectClosure {
5150 G1CollectedHeap* _g1;
5151 public:
5152 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5153 void do_object(oop p) { assert(false, "Do not call."); }
5154 bool do_object_b(oop p) {
5155 if (p != NULL) {
5156 return true;
5157 }
5158 return false;
5159 }
5160 };
5161
5162 bool G1STWIsAliveClosure::do_object_b(oop p) {
5163 // An object is reachable if it is outside the collection set,
5164 // or is inside and copied.
5165 return !_g1->obj_in_cs(p) || p->is_forwarded();
5166 }
5167
5168 // Non Copying Keep Alive closure
5169 class G1KeepAliveClosure: public OopClosure {
5170 G1CollectedHeap* _g1;
5171 public:
5172 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5173 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5174 void do_oop( oop* p) {
5175 oop obj = *p;
5176
5177 if (_g1->obj_in_cs(obj)) {
5178 assert( obj->is_forwarded(), "invariant" );
5179 *p = obj->forwardee();
5180 }
5181 }
5182 };
5183
5184 // Copying Keep Alive closure - can be called from both
5185 // serial and parallel code as long as different worker
5186 // threads utilize different G1ParScanThreadState instances
5187 // and different queues.
5188
5189 class G1CopyingKeepAliveClosure: public OopClosure {
5190 G1CollectedHeap* _g1h;
5191 OopClosure* _copy_non_heap_obj_cl;
5192 OopsInHeapRegionClosure* _copy_perm_obj_cl;
5193 G1ParScanThreadState* _par_scan_state;
5194
5195 public:
5196 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5197 OopClosure* non_heap_obj_cl,
5198 OopsInHeapRegionClosure* perm_obj_cl,
5199 G1ParScanThreadState* pss):
5200 _g1h(g1h),
5201 _copy_non_heap_obj_cl(non_heap_obj_cl),
5202 _copy_perm_obj_cl(perm_obj_cl),
5203 _par_scan_state(pss)
5204 {}
5205
5206 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5207 virtual void do_oop( oop* p) { do_oop_work(p); }
5208
5209 template <class T> void do_oop_work(T* p) {
5210 oop obj = oopDesc::load_decode_heap_oop(p);
5211
5212 if (_g1h->obj_in_cs(obj)) {
5213 // If the referent object has been forwarded (either copied
5214 // to a new location or to itself in the event of an
5215 // evacuation failure) then we need to update the reference
5216 // field and, if both reference and referent are in the G1
5217 // heap, update the RSet for the referent.
5218 //
5219 // If the referent has not been forwarded then we have to keep
5220 // it alive by policy. Therefore we have copy the referent.
5221 //
5222 // If the reference field is in the G1 heap then we can push
5223 // on the PSS queue. When the queue is drained (after each
5224 // phase of reference processing) the object and it's followers
5225 // will be copied, the reference field set to point to the
5226 // new location, and the RSet updated. Otherwise we need to
5227 // use the the non-heap or perm closures directly to copy
5228 // the referent object and update the pointer, while avoiding
5229 // updating the RSet.
5230
5231 if (_g1h->is_in_g1_reserved(p)) {
5232 _par_scan_state->push_on_queue(p);
5233 } else {
5234 // The reference field is not in the G1 heap.
5235 if (_g1h->perm_gen()->is_in(p)) {
5236 _copy_perm_obj_cl->do_oop(p);
5237 } else {
5238 _copy_non_heap_obj_cl->do_oop(p);
5239 }
5240 }
5241 }
5242 }
5243 };
5244
5245 // Serial drain queue closure. Called as the 'complete_gc'
5246 // closure for each discovered list in some of the
5247 // reference processing phases.
5248
5249 class G1STWDrainQueueClosure: public VoidClosure {
5250 protected:
5251 G1CollectedHeap* _g1h;
5252 G1ParScanThreadState* _par_scan_state;
5253
5254 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5255
5256 public:
5257 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5258 _g1h(g1h),
5259 _par_scan_state(pss)
5260 { }
5261
5262 void do_void() {
5263 G1ParScanThreadState* const pss = par_scan_state();
5264 pss->trim_queue();
5265 }
5266 };
5267
5268 // Parallel Reference Processing closures
5269
5270 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5271 // processing during G1 evacuation pauses.
5272
5273 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5274 private:
5275 G1CollectedHeap* _g1h;
5276 RefToScanQueueSet* _queues;
5277 FlexibleWorkGang* _workers;
5278 int _active_workers;
5279
5280 public:
5281 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5282 FlexibleWorkGang* workers,
5283 RefToScanQueueSet *task_queues,
5284 int n_workers) :
5285 _g1h(g1h),
5286 _queues(task_queues),
5287 _workers(workers),
5288 _active_workers(n_workers)
5289 {
5290 assert(n_workers > 0, "shouldn't call this otherwise");
5291 }
5292
5293 // Executes the given task using concurrent marking worker threads.
5294 virtual void execute(ProcessTask& task);
5295 virtual void execute(EnqueueTask& task);
5296 };
5297
5298 // Gang task for possibly parallel reference processing
5299
5300 class G1STWRefProcTaskProxy: public AbstractGangTask {
5301 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5302 ProcessTask& _proc_task;
5303 G1CollectedHeap* _g1h;
5304 RefToScanQueueSet *_task_queues;
5305 ParallelTaskTerminator* _terminator;
5306
5307 public:
5308 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5309 G1CollectedHeap* g1h,
5310 RefToScanQueueSet *task_queues,
5311 ParallelTaskTerminator* terminator) :
5312 AbstractGangTask("Process reference objects in parallel"),
5313 _proc_task(proc_task),
5314 _g1h(g1h),
5315 _task_queues(task_queues),
5316 _terminator(terminator)
5317 {}
5318
5319 virtual void work(uint worker_id) {
5320 // The reference processing task executed by a single worker.
5321 ResourceMark rm;
5322 HandleMark hm;
5323
5324 G1STWIsAliveClosure is_alive(_g1h);
5325
5326 G1ParScanThreadState pss(_g1h, worker_id);
5327
5328 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5329 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5330 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5331
5332 pss.set_evac_closure(&scan_evac_cl);
5333 pss.set_evac_failure_closure(&evac_failure_cl);
5334 pss.set_partial_scan_closure(&partial_scan_cl);
5335
5336 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5337 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5338
5339 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5340 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5341
5342 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5343 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5344
5345 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5346 // We also need to mark copied objects.
5347 copy_non_heap_cl = ©_mark_non_heap_cl;
5348 copy_perm_cl = ©_mark_perm_cl;
5349 }
5350
5351 // Keep alive closure.
5352 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5353
5354 // Complete GC closure
5355 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5356
5357 // Call the reference processing task's work routine.
5358 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5359
5360 // Note we cannot assert that the refs array is empty here as not all
5361 // of the processing tasks (specifically phase2 - pp2_work) execute
5362 // the complete_gc closure (which ordinarily would drain the queue) so
5363 // the queue may not be empty.
5364 }
5365 };
5366
5367 // Driver routine for parallel reference processing.
5368 // Creates an instance of the ref processing gang
5369 // task and has the worker threads execute it.
5370 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5371 assert(_workers != NULL, "Need parallel worker threads.");
5372
5373 ParallelTaskTerminator terminator(_active_workers, _queues);
5374 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5375
5376 _g1h->set_par_threads(_active_workers);
5377 _workers->run_task(&proc_task_proxy);
5378 _g1h->set_par_threads(0);
5379 }
5380
5381 // Gang task for parallel reference enqueueing.
5382
5383 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5384 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5385 EnqueueTask& _enq_task;
5386
5387 public:
5388 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5389 AbstractGangTask("Enqueue reference objects in parallel"),
5390 _enq_task(enq_task)
5391 { }
5392
5393 virtual void work(uint worker_id) {
5394 _enq_task.work(worker_id);
5395 }
5396 };
5397
5398 // Driver routine for parallel reference enqueueing.
5399 // Creates an instance of the ref enqueueing gang
5400 // task and has the worker threads execute it.
5401
5402 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5403 assert(_workers != NULL, "Need parallel worker threads.");
5404
5405 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5406
5407 _g1h->set_par_threads(_active_workers);
5408 _workers->run_task(&enq_task_proxy);
5409 _g1h->set_par_threads(0);
5410 }
5411
5412 // End of weak reference support closures
5413
5414 // Abstract task used to preserve (i.e. copy) any referent objects
5415 // that are in the collection set and are pointed to by reference
5416 // objects discovered by the CM ref processor.
5417
5418 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5419 protected:
5420 G1CollectedHeap* _g1h;
5421 RefToScanQueueSet *_queues;
5422 ParallelTaskTerminator _terminator;
5423 uint _n_workers;
5424
5425 public:
5426 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5427 AbstractGangTask("ParPreserveCMReferents"),
5428 _g1h(g1h),
5429 _queues(task_queues),
5430 _terminator(workers, _queues),
5431 _n_workers(workers)
5432 { }
5433
5434 void work(uint worker_id) {
5435 ResourceMark rm;
5436 HandleMark hm;
5437
5438 G1ParScanThreadState pss(_g1h, worker_id);
5439 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5440 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5441 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5442
5443 pss.set_evac_closure(&scan_evac_cl);
5444 pss.set_evac_failure_closure(&evac_failure_cl);
5445 pss.set_partial_scan_closure(&partial_scan_cl);
5446
5447 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5448
5449
5450 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5451 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5452
5453 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5454 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5455
5456 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5457 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5458
5459 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5460 // We also need to mark copied objects.
5461 copy_non_heap_cl = ©_mark_non_heap_cl;
5462 copy_perm_cl = ©_mark_perm_cl;
5463 }
5464
5465 // Is alive closure
5466 G1AlwaysAliveClosure always_alive(_g1h);
5467
5468 // Copying keep alive closure. Applied to referent objects that need
5469 // to be copied.
5470 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5471
5472 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5473
5474 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5475 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5476
5477 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5478 // So this must be true - but assert just in case someone decides to
5479 // change the worker ids.
5480 assert(0 <= worker_id && worker_id < limit, "sanity");
5481 assert(!rp->discovery_is_atomic(), "check this code");
5482
5483 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5484 for (uint idx = worker_id; idx < limit; idx += stride) {
5485 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5486
5487 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5488 while (iter.has_next()) {
5489 // Since discovery is not atomic for the CM ref processor, we
5490 // can see some null referent objects.
5491 iter.load_ptrs(DEBUG_ONLY(true));
5492 oop ref = iter.obj();
5493
5494 // This will filter nulls.
5495 if (iter.is_referent_alive()) {
5496 iter.make_referent_alive();
5497 }
5498 iter.move_to_next();
5499 }
5500 }
5501
5502 // Drain the queue - which may cause stealing
5503 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5504 drain_queue.do_void();
5505 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5506 assert(pss.refs()->is_empty(), "should be");
5507 }
5508 };
5509
5510 // Weak Reference processing during an evacuation pause (part 1).
5511 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5512 double ref_proc_start = os::elapsedTime();
5513
5514 ReferenceProcessor* rp = _ref_processor_stw;
5515 assert(rp->discovery_enabled(), "should have been enabled");
5516
5517 // Any reference objects, in the collection set, that were 'discovered'
5518 // by the CM ref processor should have already been copied (either by
5519 // applying the external root copy closure to the discovered lists, or
5520 // by following an RSet entry).
5521 //
5522 // But some of the referents, that are in the collection set, that these
5523 // reference objects point to may not have been copied: the STW ref
5524 // processor would have seen that the reference object had already
5525 // been 'discovered' and would have skipped discovering the reference,
5526 // but would not have treated the reference object as a regular oop.
5527 // As a result the copy closure would not have been applied to the
5528 // referent object.
5529 //
5530 // We need to explicitly copy these referent objects - the references
5531 // will be processed at the end of remarking.
5532 //
5533 // We also need to do this copying before we process the reference
5534 // objects discovered by the STW ref processor in case one of these
5535 // referents points to another object which is also referenced by an
5536 // object discovered by the STW ref processor.
5537
5538 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5539 no_of_gc_workers == workers()->active_workers(),
5540 "Need to reset active GC workers");
5541
5542 set_par_threads(no_of_gc_workers);
5543 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5544 no_of_gc_workers,
5545 _task_queues);
5546
5547 if (G1CollectedHeap::use_parallel_gc_threads()) {
5548 workers()->run_task(&keep_cm_referents);
5549 } else {
5550 keep_cm_referents.work(0);
5551 }
5552
5553 set_par_threads(0);
5554
5555 // Closure to test whether a referent is alive.
5556 G1STWIsAliveClosure is_alive(this);
5557
5558 // Even when parallel reference processing is enabled, the processing
5559 // of JNI refs is serial and performed serially by the current thread
5560 // rather than by a worker. The following PSS will be used for processing
5561 // JNI refs.
5562
5563 // Use only a single queue for this PSS.
5564 G1ParScanThreadState pss(this, 0);
5565
5566 // We do not embed a reference processor in the copying/scanning
5567 // closures while we're actually processing the discovered
5568 // reference objects.
5569 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5570 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5571 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5572
5573 pss.set_evac_closure(&scan_evac_cl);
5574 pss.set_evac_failure_closure(&evac_failure_cl);
5575 pss.set_partial_scan_closure(&partial_scan_cl);
5576
5577 assert(pss.refs()->is_empty(), "pre-condition");
5578
5579 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5580 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL);
5581
5582 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5583 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL);
5584
5585 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5586 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5587
5588 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5589 // We also need to mark copied objects.
5590 copy_non_heap_cl = ©_mark_non_heap_cl;
5591 copy_perm_cl = ©_mark_perm_cl;
5592 }
5593
5594 // Keep alive closure.
5595 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5596
5597 // Serial Complete GC closure
5598 G1STWDrainQueueClosure drain_queue(this, &pss);
5599
5600 // Setup the soft refs policy...
5601 rp->setup_policy(false);
5602
5603 ReferenceProcessorStats stats;
5604 if (!rp->processing_is_mt()) {
5605 // Serial reference processing...
5606 stats = rp->process_discovered_references(&is_alive,
5607 &keep_alive,
5608 &drain_queue,
5609 NULL,
5610 _gc_timer_stw);
5611 } else {
5612 // Parallel reference processing
5613 assert(rp->num_q() == no_of_gc_workers, "sanity");
5614 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5615
5616 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5617 stats = rp->process_discovered_references(&is_alive,
5618 &keep_alive,
5619 &drain_queue,
5620 &par_task_executor,
5621 _gc_timer_stw);
5622 }
5623
5624 _gc_tracer_stw->report_gc_reference_stats(stats);
5625 // We have completed copying any necessary live referent objects
5626 // (that were not copied during the actual pause) so we can
5627 // retire any active alloc buffers
5628 pss.retire_alloc_buffers();
5629 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5630
5631 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5632 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5633 }
5634
5635 // Weak Reference processing during an evacuation pause (part 2).
5636 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5637 double ref_enq_start = os::elapsedTime();
5638
5639 ReferenceProcessor* rp = _ref_processor_stw;
5640 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5641
5642 // Now enqueue any remaining on the discovered lists on to
5643 // the pending list.
5644 if (!rp->processing_is_mt()) {
5645 // Serial reference processing...
5646 rp->enqueue_discovered_references();
5647 } else {
5648 // Parallel reference enqueueing
5649
5650 assert(no_of_gc_workers == workers()->active_workers(),
5651 "Need to reset active workers");
5652 assert(rp->num_q() == no_of_gc_workers, "sanity");
5653 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5654
5655 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5656 rp->enqueue_discovered_references(&par_task_executor);
5657 }
5658
5659 rp->verify_no_references_recorded();
5660 assert(!rp->discovery_enabled(), "should have been disabled");
5661
5662 // FIXME
5663 // CM's reference processing also cleans up the string and symbol tables.
5664 // Should we do that here also? We could, but it is a serial operation
5665 // and could significantly increase the pause time.
5666
5667 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5668 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5669 }
5670
5671 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5672 _expand_heap_after_alloc_failure = true;
5673 _evacuation_failed = false;
5674
5675 // Should G1EvacuationFailureALot be in effect for this GC?
5676 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5677
5678 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5679 concurrent_g1_refine()->set_use_cache(false);
5680 concurrent_g1_refine()->clear_hot_cache_claimed_index();
5681
5682 uint n_workers;
5683 if (G1CollectedHeap::use_parallel_gc_threads()) {
5684 n_workers =
5685 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5686 workers()->active_workers(),
5687 Threads::number_of_non_daemon_threads());
5688 assert(UseDynamicNumberOfGCThreads ||
5689 n_workers == workers()->total_workers(),
5690 "If not dynamic should be using all the workers");
5691 workers()->set_active_workers(n_workers);
5692 set_par_threads(n_workers);
5693 } else {
5694 assert(n_par_threads() == 0,
5695 "Should be the original non-parallel value");
5696 n_workers = 1;
5697 }
5698
5699 G1ParTask g1_par_task(this, _task_queues);
5700
5701 init_for_evac_failure(NULL);
5702
5703 rem_set()->prepare_for_younger_refs_iterate(true);
5704
5705 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5706 double start_par_time_sec = os::elapsedTime();
5707 double end_par_time_sec;
5708
5709 {
5710 StrongRootsScope srs(this);
5711
5712 if (G1CollectedHeap::use_parallel_gc_threads()) {
5713 // The individual threads will set their evac-failure closures.
5714 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5715 // These tasks use ShareHeap::_process_strong_tasks
5716 assert(UseDynamicNumberOfGCThreads ||
5717 workers()->active_workers() == workers()->total_workers(),
5718 "If not dynamic should be using all the workers");
5719 workers()->run_task(&g1_par_task);
5720 } else {
5721 g1_par_task.set_for_termination(n_workers);
5722 g1_par_task.work(0);
5723 }
5724 end_par_time_sec = os::elapsedTime();
5725
5726 // Closing the inner scope will execute the destructor
5727 // for the StrongRootsScope object. We record the current
5728 // elapsed time before closing the scope so that time
5729 // taken for the SRS destructor is NOT included in the
5730 // reported parallel time.
5731 }
5732
5733 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5734 g1_policy()->phase_times()->record_par_time(par_time_ms);
5735
5736 double code_root_fixup_time_ms =
5737 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5738 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5739
5740 set_par_threads(0);
5741
5742 // Process any discovered reference objects - we have
5743 // to do this _before_ we retire the GC alloc regions
5744 // as we may have to copy some 'reachable' referent
5745 // objects (and their reachable sub-graphs) that were
5746 // not copied during the pause.
5747 process_discovered_references(n_workers);
5748
5749 // Weak root processing.
5750 // Note: when JSR 292 is enabled and code blobs can contain
5751 // non-perm oops then we will need to process the code blobs
5752 // here too.
5753 {
5754 G1STWIsAliveClosure is_alive(this);
5755 G1KeepAliveClosure keep_alive(this);
5756 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5757 }
5758
5759 release_gc_alloc_regions(n_workers, evacuation_info);
5760 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5761
5762 concurrent_g1_refine()->clear_hot_cache();
5763 concurrent_g1_refine()->set_use_cache(true);
5764
5765 finalize_for_evac_failure();
5766
5767 if (evacuation_failed()) {
5768 remove_self_forwarding_pointers();
5769
5770 // Reset the G1EvacuationFailureALot counters and flags
5771 // Note: the values are reset only when an actual
5772 // evacuation failure occurs.
5773 NOT_PRODUCT(reset_evacuation_should_fail();)
5774 }
5775
5776 // Enqueue any remaining references remaining on the STW
5777 // reference processor's discovered lists. We need to do
5778 // this after the card table is cleaned (and verified) as
5779 // the act of enqueueing entries on to the pending list
5780 // will log these updates (and dirty their associated
5781 // cards). We need these updates logged to update any
5782 // RSets.
5783 enqueue_discovered_references(n_workers);
5784
5785 if (G1DeferredRSUpdate) {
5786 RedirtyLoggedCardTableEntryFastClosure redirty;
5787 dirty_card_queue_set().set_closure(&redirty);
5788 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5789
5790 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5791 dcq.merge_bufferlists(&dirty_card_queue_set());
5792 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5793 }
5794 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5795 }
5796
5797 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5798 size_t* pre_used,
5799 FreeRegionList* free_list,
5800 OldRegionSet* old_proxy_set,
5801 HumongousRegionSet* humongous_proxy_set,
5802 HRRSCleanupTask* hrrs_cleanup_task,
5803 bool par) {
5804 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5805 if (hr->isHumongous()) {
5806 assert(hr->startsHumongous(), "we should only see starts humongous");
5807 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5808 } else {
5809 _old_set.remove_with_proxy(hr, old_proxy_set);
5810 free_region(hr, pre_used, free_list, par);
5811 }
5812 } else {
5813 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5814 }
5815 }
5816
5817 void G1CollectedHeap::free_region(HeapRegion* hr,
5818 size_t* pre_used,
5819 FreeRegionList* free_list,
5820 bool par) {
5821 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5822 assert(!hr->is_empty(), "the region should not be empty");
5823 assert(free_list != NULL, "pre-condition");
5824
5825 *pre_used += hr->used();
5826 hr->hr_clear(par, true /* clear_space */);
5827 free_list->add_as_head(hr);
5828 }
5829
5830 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5831 size_t* pre_used,
5832 FreeRegionList* free_list,
5833 HumongousRegionSet* humongous_proxy_set,
5834 bool par) {
5835 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5836 assert(free_list != NULL, "pre-condition");
5837 assert(humongous_proxy_set != NULL, "pre-condition");
5838
5839 size_t hr_used = hr->used();
5840 size_t hr_capacity = hr->capacity();
5841 size_t hr_pre_used = 0;
5842 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5843 // We need to read this before we make the region non-humongous,
5844 // otherwise the information will be gone.
5845 uint last_index = hr->last_hc_index();
5846 hr->set_notHumongous();
5847 free_region(hr, &hr_pre_used, free_list, par);
5848
5849 uint i = hr->hrs_index() + 1;
5850 while (i < last_index) {
5851 HeapRegion* curr_hr = region_at(i);
5852 assert(curr_hr->continuesHumongous(), "invariant");
5853 curr_hr->set_notHumongous();
5854 free_region(curr_hr, &hr_pre_used, free_list, par);
5855 i += 1;
5856 }
5857 assert(hr_pre_used == hr_used,
5858 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5859 "should be the same", hr_pre_used, hr_used));
5860 *pre_used += hr_pre_used;
5861 }
5862
5863 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5864 FreeRegionList* free_list,
5865 OldRegionSet* old_proxy_set,
5866 HumongousRegionSet* humongous_proxy_set,
5867 bool par) {
5868 if (pre_used > 0) {
5869 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5870 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5871 assert(_summary_bytes_used >= pre_used,
5872 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5873 "should be >= pre_used: "SIZE_FORMAT,
5874 _summary_bytes_used, pre_used));
5875 _summary_bytes_used -= pre_used;
5876 }
5877 if (free_list != NULL && !free_list->is_empty()) {
5878 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5879 _free_list.add_as_head(free_list);
5880 }
5881 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5882 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5883 _old_set.update_from_proxy(old_proxy_set);
5884 }
5885 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5886 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5887 _humongous_set.update_from_proxy(humongous_proxy_set);
5888 }
5889 }
5890
5891 class G1ParCleanupCTTask : public AbstractGangTask {
5892 CardTableModRefBS* _ct_bs;
5893 G1CollectedHeap* _g1h;
5894 HeapRegion* volatile _su_head;
5895 public:
5896 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5897 G1CollectedHeap* g1h) :
5898 AbstractGangTask("G1 Par Cleanup CT Task"),
5899 _ct_bs(ct_bs), _g1h(g1h) { }
5900
5901 void work(uint worker_id) {
5902 HeapRegion* r;
5903 while (r = _g1h->pop_dirty_cards_region()) {
5904 clear_cards(r);
5905 }
5906 }
5907
5908 void clear_cards(HeapRegion* r) {
5909 // Cards of the survivors should have already been dirtied.
5910 if (!r->is_survivor()) {
5911 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5912 }
5913 }
5914 };
5915
5916 #ifndef PRODUCT
5917 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5918 G1CollectedHeap* _g1h;
5919 CardTableModRefBS* _ct_bs;
5920 public:
5921 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5922 : _g1h(g1h), _ct_bs(ct_bs) { }
5923 virtual bool doHeapRegion(HeapRegion* r) {
5924 if (r->is_survivor()) {
5925 _g1h->verify_dirty_region(r);
5926 } else {
5927 _g1h->verify_not_dirty_region(r);
5928 }
5929 return false;
5930 }
5931 };
5932
5933 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5934 // All of the region should be clean.
5935 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5936 MemRegion mr(hr->bottom(), hr->end());
5937 ct_bs->verify_not_dirty_region(mr);
5938 }
5939
5940 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5941 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5942 // dirty allocated blocks as they allocate them. The thread that
5943 // retires each region and replaces it with a new one will do a
5944 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5945 // not dirty that area (one less thing to have to do while holding
5946 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5947 // is dirty.
5948 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5949 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5950 ct_bs->verify_dirty_region(mr);
5951 }
5952
5953 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5954 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5955 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5956 verify_dirty_region(hr);
5957 }
5958 }
5959
5960 void G1CollectedHeap::verify_dirty_young_regions() {
5961 verify_dirty_young_list(_young_list->first_region());
5962 }
5963 #endif
5964
5965 void G1CollectedHeap::cleanUpCardTable() {
5966 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5967 double start = os::elapsedTime();
5968
5969 {
5970 // Iterate over the dirty cards region list.
5971 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5972
5973 if (G1CollectedHeap::use_parallel_gc_threads()) {
5974 set_par_threads();
5975 workers()->run_task(&cleanup_task);
5976 set_par_threads(0);
5977 } else {
5978 while (_dirty_cards_region_list) {
5979 HeapRegion* r = _dirty_cards_region_list;
5980 cleanup_task.clear_cards(r);
5981 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5982 if (_dirty_cards_region_list == r) {
5983 // The last region.
5984 _dirty_cards_region_list = NULL;
5985 }
5986 r->set_next_dirty_cards_region(NULL);
5987 }
5988 }
5989 #ifndef PRODUCT
5990 if (G1VerifyCTCleanup || VerifyAfterGC) {
5991 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5992 heap_region_iterate(&cleanup_verifier);
5993 }
5994 #endif
5995 }
5996
5997 double elapsed = os::elapsedTime() - start;
5998 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5999 }
6000
6001 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6002 size_t pre_used = 0;
6003 FreeRegionList local_free_list("Local List for CSet Freeing");
6004
6005 double young_time_ms = 0.0;
6006 double non_young_time_ms = 0.0;
6007
6008 // Since the collection set is a superset of the the young list,
6009 // all we need to do to clear the young list is clear its
6010 // head and length, and unlink any young regions in the code below
6011 _young_list->clear();
6012
6013 G1CollectorPolicy* policy = g1_policy();
6014
6015 double start_sec = os::elapsedTime();
6016 bool non_young = true;
6017
6018 HeapRegion* cur = cs_head;
6019 int age_bound = -1;
6020 size_t rs_lengths = 0;
6021
6022 while (cur != NULL) {
6023 assert(!is_on_master_free_list(cur), "sanity");
6024 if (non_young) {
6025 if (cur->is_young()) {
6026 double end_sec = os::elapsedTime();
6027 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6028 non_young_time_ms += elapsed_ms;
6029
6030 start_sec = os::elapsedTime();
6031 non_young = false;
6032 }
6033 } else {
6034 if (!cur->is_young()) {
6035 double end_sec = os::elapsedTime();
6036 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6037 young_time_ms += elapsed_ms;
6038
6039 start_sec = os::elapsedTime();
6040 non_young = true;
6041 }
6042 }
6043
6044 rs_lengths += cur->rem_set()->occupied();
6045
6046 HeapRegion* next = cur->next_in_collection_set();
6047 assert(cur->in_collection_set(), "bad CS");
6048 cur->set_next_in_collection_set(NULL);
6049 cur->set_in_collection_set(false);
6050
6051 if (cur->is_young()) {
6052 int index = cur->young_index_in_cset();
6053 assert(index != -1, "invariant");
6054 assert((uint) index < policy->young_cset_region_length(), "invariant");
6055 size_t words_survived = _surviving_young_words[index];
6056 cur->record_surv_words_in_group(words_survived);
6057
6058 // At this point the we have 'popped' cur from the collection set
6059 // (linked via next_in_collection_set()) but it is still in the
6060 // young list (linked via next_young_region()). Clear the
6061 // _next_young_region field.
6062 cur->set_next_young_region(NULL);
6063 } else {
6064 int index = cur->young_index_in_cset();
6065 assert(index == -1, "invariant");
6066 }
6067
6068 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6069 (!cur->is_young() && cur->young_index_in_cset() == -1),
6070 "invariant" );
6071
6072 if (!cur->evacuation_failed()) {
6073 MemRegion used_mr = cur->used_region();
6074
6075 // And the region is empty.
6076 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6077 free_region(cur, &pre_used, &local_free_list, false /* par */);
6078 } else {
6079 cur->uninstall_surv_rate_group();
6080 if (cur->is_young()) {
6081 cur->set_young_index_in_cset(-1);
6082 }
6083 cur->set_not_young();
6084 cur->set_evacuation_failed(false);
6085 // The region is now considered to be old.
6086 _old_set.add(cur);
6087 evacuation_info.increment_collectionset_used_after(cur->used());
6088 }
6089 cur = next;
6090 }
6091
6092 evacuation_info.set_regions_freed(local_free_list.length());
6093 policy->record_max_rs_lengths(rs_lengths);
6094 policy->cset_regions_freed();
6095
6096 double end_sec = os::elapsedTime();
6097 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6098
6099 if (non_young) {
6100 non_young_time_ms += elapsed_ms;
6101 } else {
6102 young_time_ms += elapsed_ms;
6103 }
6104
6105 update_sets_after_freeing_regions(pre_used, &local_free_list,
6106 NULL /* old_proxy_set */,
6107 NULL /* humongous_proxy_set */,
6108 false /* par */);
6109 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6110 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6111 }
6112
6113 // This routine is similar to the above but does not record
6114 // any policy statistics or update free lists; we are abandoning
6115 // the current incremental collection set in preparation of a
6116 // full collection. After the full GC we will start to build up
6117 // the incremental collection set again.
6118 // This is only called when we're doing a full collection
6119 // and is immediately followed by the tearing down of the young list.
6120
6121 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6122 HeapRegion* cur = cs_head;
6123
6124 while (cur != NULL) {
6125 HeapRegion* next = cur->next_in_collection_set();
6126 assert(cur->in_collection_set(), "bad CS");
6127 cur->set_next_in_collection_set(NULL);
6128 cur->set_in_collection_set(false);
6129 cur->set_young_index_in_cset(-1);
6130 cur = next;
6131 }
6132 }
6133
6134 void G1CollectedHeap::set_free_regions_coming() {
6135 if (G1ConcRegionFreeingVerbose) {
6136 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6137 "setting free regions coming");
6138 }
6139
6140 assert(!free_regions_coming(), "pre-condition");
6141 _free_regions_coming = true;
6142 }
6143
6144 void G1CollectedHeap::reset_free_regions_coming() {
6145 assert(free_regions_coming(), "pre-condition");
6146
6147 {
6148 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6149 _free_regions_coming = false;
6150 SecondaryFreeList_lock->notify_all();
6151 }
6152
6153 if (G1ConcRegionFreeingVerbose) {
6154 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6155 "reset free regions coming");
6156 }
6157 }
6158
6159 void G1CollectedHeap::wait_while_free_regions_coming() {
6160 // Most of the time we won't have to wait, so let's do a quick test
6161 // first before we take the lock.
6162 if (!free_regions_coming()) {
6163 return;
6164 }
6165
6166 if (G1ConcRegionFreeingVerbose) {
6167 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6168 "waiting for free regions");
6169 }
6170
6171 {
6172 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6173 while (free_regions_coming()) {
6174 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6175 }
6176 }
6177
6178 if (G1ConcRegionFreeingVerbose) {
6179 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6180 "done waiting for free regions");
6181 }
6182 }
6183
6184 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6185 assert(heap_lock_held_for_gc(),
6186 "the heap lock should already be held by or for this thread");
6187 _young_list->push_region(hr);
6188 }
6189
6190 class NoYoungRegionsClosure: public HeapRegionClosure {
6191 private:
6192 bool _success;
6193 public:
6194 NoYoungRegionsClosure() : _success(true) { }
6195 bool doHeapRegion(HeapRegion* r) {
6196 if (r->is_young()) {
6197 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6198 r->bottom(), r->end());
6199 _success = false;
6200 }
6201 return false;
6202 }
6203 bool success() { return _success; }
6204 };
6205
6206 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6207 bool ret = _young_list->check_list_empty(check_sample);
6208
6209 if (check_heap) {
6210 NoYoungRegionsClosure closure;
6211 heap_region_iterate(&closure);
6212 ret = ret && closure.success();
6213 }
6214
6215 return ret;
6216 }
6217
6218 class TearDownRegionSetsClosure : public HeapRegionClosure {
6219 private:
6220 OldRegionSet *_old_set;
6221
6222 public:
6223 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6224
6225 bool doHeapRegion(HeapRegion* r) {
6226 if (r->is_empty()) {
6227 // We ignore empty regions, we'll empty the free list afterwards
6228 } else if (r->is_young()) {
6229 // We ignore young regions, we'll empty the young list afterwards
6230 } else if (r->isHumongous()) {
6231 // We ignore humongous regions, we're not tearing down the
6232 // humongous region set
6233 } else {
6234 // The rest should be old
6235 _old_set->remove(r);
6236 }
6237 return false;
6238 }
6239
6240 ~TearDownRegionSetsClosure() {
6241 assert(_old_set->is_empty(), "post-condition");
6242 }
6243 };
6244
6245 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6246 assert_at_safepoint(true /* should_be_vm_thread */);
6247
6248 if (!free_list_only) {
6249 TearDownRegionSetsClosure cl(&_old_set);
6250 heap_region_iterate(&cl);
6251
6252 // Need to do this after the heap iteration to be able to
6253 // recognize the young regions and ignore them during the iteration.
6254 _young_list->empty_list();
6255 }
6256 _free_list.remove_all();
6257 }
6258
6259 class RebuildRegionSetsClosure : public HeapRegionClosure {
6260 private:
6261 bool _free_list_only;
6262 OldRegionSet* _old_set;
6263 FreeRegionList* _free_list;
6264 size_t _total_used;
6265
6266 public:
6267 RebuildRegionSetsClosure(bool free_list_only,
6268 OldRegionSet* old_set, FreeRegionList* free_list) :
6269 _free_list_only(free_list_only),
6270 _old_set(old_set), _free_list(free_list), _total_used(0) {
6271 assert(_free_list->is_empty(), "pre-condition");
6272 if (!free_list_only) {
6273 assert(_old_set->is_empty(), "pre-condition");
6274 }
6275 }
6276
6277 bool doHeapRegion(HeapRegion* r) {
6278 if (r->continuesHumongous()) {
6279 return false;
6280 }
6281
6282 if (r->is_empty()) {
6283 // Add free regions to the free list
6284 _free_list->add_as_tail(r);
6285 } else if (!_free_list_only) {
6286 assert(!r->is_young(), "we should not come across young regions");
6287
6288 if (r->isHumongous()) {
6289 // We ignore humongous regions, we left the humongous set unchanged
6290 } else {
6291 // The rest should be old, add them to the old set
6292 _old_set->add(r);
6293 }
6294 _total_used += r->used();
6295 }
6296
6297 return false;
6298 }
6299
6300 size_t total_used() {
6301 return _total_used;
6302 }
6303 };
6304
6305 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6306 assert_at_safepoint(true /* should_be_vm_thread */);
6307
6308 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6309 heap_region_iterate(&cl);
6310
6311 if (!free_list_only) {
6312 _summary_bytes_used = cl.total_used();
6313 }
6314 assert(_summary_bytes_used == recalculate_used(),
6315 err_msg("inconsistent _summary_bytes_used, "
6316 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6317 _summary_bytes_used, recalculate_used()));
6318 }
6319
6320 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6321 _refine_cte_cl->set_concurrent(concurrent);
6322 }
6323
6324 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6325 HeapRegion* hr = heap_region_containing(p);
6326 if (hr == NULL) {
6327 return is_in_permanent(p);
6328 } else {
6329 return hr->is_in(p);
6330 }
6331 }
6332
6333 // Methods for the mutator alloc region
6334
6335 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6336 bool force) {
6337 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6338 assert(!force || g1_policy()->can_expand_young_list(),
6339 "if force is true we should be able to expand the young list");
6340 bool young_list_full = g1_policy()->is_young_list_full();
6341 if (force || !young_list_full) {
6342 HeapRegion* new_alloc_region = new_region(word_size,
6343 false /* do_expand */);
6344 if (new_alloc_region != NULL) {
6345 set_region_short_lived_locked(new_alloc_region);
6346 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6347 return new_alloc_region;
6348 }
6349 }
6350 return NULL;
6351 }
6352
6353 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6354 size_t allocated_bytes) {
6355 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6356 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6357
6358 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6359 _summary_bytes_used += allocated_bytes;
6360 _hr_printer.retire(alloc_region);
6361 // We update the eden sizes here, when the region is retired,
6362 // instead of when it's allocated, since this is the point that its
6363 // used space has been recored in _summary_bytes_used.
6364 g1mm()->update_eden_size();
6365 }
6366
6367 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6368 bool force) {
6369 return _g1h->new_mutator_alloc_region(word_size, force);
6370 }
6371
6372 void G1CollectedHeap::set_par_threads() {
6373 // Don't change the number of workers. Use the value previously set
6374 // in the workgroup.
6375 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6376 uint n_workers = workers()->active_workers();
6377 assert(UseDynamicNumberOfGCThreads ||
6378 n_workers == workers()->total_workers(),
6379 "Otherwise should be using the total number of workers");
6380 if (n_workers == 0) {
6381 assert(false, "Should have been set in prior evacuation pause.");
6382 n_workers = ParallelGCThreads;
6383 workers()->set_active_workers(n_workers);
6384 }
6385 set_par_threads(n_workers);
6386 }
6387
6388 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6389 size_t allocated_bytes) {
6390 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6391 }
6392
6393 // Methods for the GC alloc regions
6394
6395 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6396 uint count,
6397 GCAllocPurpose ap) {
6398 assert(FreeList_lock->owned_by_self(), "pre-condition");
6399
6400 if (count < g1_policy()->max_regions(ap)) {
6401 HeapRegion* new_alloc_region = new_region(word_size,
6402 true /* do_expand */);
6403 if (new_alloc_region != NULL) {
6404 // We really only need to do this for old regions given that we
6405 // should never scan survivors. But it doesn't hurt to do it
6406 // for survivors too.
6407 new_alloc_region->set_saved_mark();
6408 if (ap == GCAllocForSurvived) {
6409 new_alloc_region->set_survivor();
6410 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6411 } else {
6412 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6413 }
6414 bool during_im = g1_policy()->during_initial_mark_pause();
6415 new_alloc_region->note_start_of_copying(during_im);
6416 return new_alloc_region;
6417 } else {
6418 g1_policy()->note_alloc_region_limit_reached(ap);
6419 }
6420 }
6421 return NULL;
6422 }
6423
6424 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6425 size_t allocated_bytes,
6426 GCAllocPurpose ap) {
6427 bool during_im = g1_policy()->during_initial_mark_pause();
6428 alloc_region->note_end_of_copying(during_im);
6429 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6430 if (ap == GCAllocForSurvived) {
6431 young_list()->add_survivor_region(alloc_region);
6432 } else {
6433 _old_set.add(alloc_region);
6434 }
6435 _hr_printer.retire(alloc_region);
6436 }
6437
6438 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6439 bool force) {
6440 assert(!force, "not supported for GC alloc regions");
6441 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6442 }
6443
6444 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6445 size_t allocated_bytes) {
6446 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6447 GCAllocForSurvived);
6448 }
6449
6450 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6451 bool force) {
6452 assert(!force, "not supported for GC alloc regions");
6453 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6454 }
6455
6456 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6457 size_t allocated_bytes) {
6458 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6459 GCAllocForTenured);
6460 }
6461 // Heap region set verification
6462
6463 class VerifyRegionListsClosure : public HeapRegionClosure {
6464 private:
6465 FreeRegionList* _free_list;
6466 OldRegionSet* _old_set;
6467 HumongousRegionSet* _humongous_set;
6468 uint _region_count;
6469
6470 public:
6471 VerifyRegionListsClosure(OldRegionSet* old_set,
6472 HumongousRegionSet* humongous_set,
6473 FreeRegionList* free_list) :
6474 _old_set(old_set), _humongous_set(humongous_set),
6475 _free_list(free_list), _region_count(0) { }
6476
6477 uint region_count() { return _region_count; }
6478
6479 bool doHeapRegion(HeapRegion* hr) {
6480 _region_count += 1;
6481
6482 if (hr->continuesHumongous()) {
6483 return false;
6484 }
6485
6486 if (hr->is_young()) {
6487 // TODO
6488 } else if (hr->startsHumongous()) {
6489 _humongous_set->verify_next_region(hr);
6490 } else if (hr->is_empty()) {
6491 _free_list->verify_next_region(hr);
6492 } else {
6493 _old_set->verify_next_region(hr);
6494 }
6495 return false;
6496 }
6497 };
6498
6499 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6500 HeapWord* bottom) {
6501 HeapWord* end = bottom + HeapRegion::GrainWords;
6502 MemRegion mr(bottom, end);
6503 assert(_g1_reserved.contains(mr), "invariant");
6504 // This might return NULL if the allocation fails
6505 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6506 }
6507
6508 void G1CollectedHeap::verify_region_sets() {
6509 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6510
6511 // First, check the explicit lists.
6512 _free_list.verify();
6513 {
6514 // Given that a concurrent operation might be adding regions to
6515 // the secondary free list we have to take the lock before
6516 // verifying it.
6517 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6518 _secondary_free_list.verify();
6519 }
6520 _old_set.verify();
6521 _humongous_set.verify();
6522
6523 // If a concurrent region freeing operation is in progress it will
6524 // be difficult to correctly attributed any free regions we come
6525 // across to the correct free list given that they might belong to
6526 // one of several (free_list, secondary_free_list, any local lists,
6527 // etc.). So, if that's the case we will skip the rest of the
6528 // verification operation. Alternatively, waiting for the concurrent
6529 // operation to complete will have a non-trivial effect on the GC's
6530 // operation (no concurrent operation will last longer than the
6531 // interval between two calls to verification) and it might hide
6532 // any issues that we would like to catch during testing.
6533 if (free_regions_coming()) {
6534 return;
6535 }
6536
6537 // Make sure we append the secondary_free_list on the free_list so
6538 // that all free regions we will come across can be safely
6539 // attributed to the free_list.
6540 append_secondary_free_list_if_not_empty_with_lock();
6541
6542 // Finally, make sure that the region accounting in the lists is
6543 // consistent with what we see in the heap.
6544 _old_set.verify_start();
6545 _humongous_set.verify_start();
6546 _free_list.verify_start();
6547
6548 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6549 heap_region_iterate(&cl);
6550
6551 _old_set.verify_end();
6552 _humongous_set.verify_end();
6553 _free_list.verify_end();
6554 }