1 /*
2 * Copyright (c) 2001, 2014, 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/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1StringDedup.hpp"
43 #include "gc_implementation/g1/g1YCTypes.hpp"
44 #include "gc_implementation/g1/heapRegion.inline.hpp"
45 #include "gc_implementation/g1/heapRegionRemSet.hpp"
46 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
47 #include "gc_implementation/g1/vm_operations_g1.hpp"
48 #include "gc_implementation/shared/gcHeapSummary.hpp"
49 #include "gc_implementation/shared/gcTimer.hpp"
50 #include "gc_implementation/shared/gcTrace.hpp"
51 #include "gc_implementation/shared/gcTraceTime.hpp"
52 #include "gc_implementation/shared/isGCActiveMark.hpp"
53 #include "memory/gcLocker.inline.hpp"
54 #include "memory/generationSpec.hpp"
55 #include "memory/iterator.hpp"
56 #include "memory/referenceProcessor.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/oop.pcgc.inline.hpp"
59 #include "runtime/vmThread.hpp"
60 #include "utilities/ticks.hpp"
61
62 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
63
64 // turn it on so that the contents of the young list (scan-only /
65 // to-be-collected) are printed at "strategic" points before / during
66 // / after the collection --- this is useful for debugging
67 #define YOUNG_LIST_VERBOSE 0
68 // CURRENT STATUS
69 // This file is under construction. Search for "FIXME".
70
71 // INVARIANTS/NOTES
72 //
73 // All allocation activity covered by the G1CollectedHeap interface is
74 // serialized by acquiring the HeapLock. This happens in mem_allocate
75 // and allocate_new_tlab, which are the "entry" points to the
76 // allocation code from the rest of the JVM. (Note that this does not
77 // apply to TLAB allocation, which is not part of this interface: it
78 // is done by clients of this interface.)
79
80 // Notes on implementation of parallelism in different tasks.
81 //
82 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
83 // The number of GC workers is passed to heap_region_par_iterate_chunked().
84 // It does use run_task() which sets _n_workers in the task.
85 // G1ParTask executes g1_process_strong_roots() ->
86 // SharedHeap::process_strong_roots() which calls eventually to
87 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
88 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
89 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
90 //
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 SuspendibleThreadSet* _sts;
96 G1RemSet* _g1rs;
97 ConcurrentG1Refine* _cg1r;
98 bool _concurrent;
99 public:
100 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
101 G1RemSet* g1rs,
102 ConcurrentG1Refine* cg1r) :
103 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
104 {}
105 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
106 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
107 // This path is executed by the concurrent refine or mutator threads,
108 // concurrently, and so we do not care if card_ptr contains references
109 // that point into the collection set.
110 assert(!oops_into_cset, "should be");
111
112 if (_concurrent && _sts->should_yield()) {
113 // Caller will actually yield.
114 return false;
115 }
116 // Otherwise, we finished successfully; return true.
117 return true;
118 }
119 void set_concurrent(bool b) { _concurrent = b; }
120 };
121
122
123 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
124 int _calls;
125 G1CollectedHeap* _g1h;
126 CardTableModRefBS* _ctbs;
127 int _histo[256];
128 public:
129 ClearLoggedCardTableEntryClosure() :
130 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
131 {
132 for (int i = 0; i < 256; i++) _histo[i] = 0;
133 }
134 bool do_card_ptr(jbyte* card_ptr, uint 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), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
162
163 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
164 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
165 _calls++;
166 *card_ptr = 0;
167 }
168 return true;
169 }
170 int calls() { return _calls; }
171 };
172
173 YoungList::YoungList(G1CollectedHeap* g1h) :
174 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
175 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
176 guarantee(check_list_empty(false), "just making sure...");
177 }
178
179 void YoungList::push_region(HeapRegion *hr) {
180 assert(!hr->is_young(), "should not already be young");
181 assert(hr->get_next_young_region() == NULL, "cause it should!");
182
183 hr->set_next_young_region(_head);
184 _head = hr;
185
186 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
187 ++_length;
188 }
189
190 void YoungList::add_survivor_region(HeapRegion* hr) {
191 assert(hr->is_survivor(), "should be flagged as survivor region");
192 assert(hr->get_next_young_region() == NULL, "cause it should!");
193
194 hr->set_next_young_region(_survivor_head);
195 if (_survivor_head == NULL) {
196 _survivor_tail = hr;
197 }
198 _survivor_head = hr;
199 ++_survivor_length;
200 }
201
202 void YoungList::empty_list(HeapRegion* list) {
203 while (list != NULL) {
204 HeapRegion* next = list->get_next_young_region();
205 list->set_next_young_region(NULL);
206 list->uninstall_surv_rate_group();
207 list->set_not_young();
208 list = next;
209 }
210 }
211
212 void YoungList::empty_list() {
213 assert(check_list_well_formed(), "young list should be well formed");
214
215 empty_list(_head);
216 _head = NULL;
217 _length = 0;
218
219 empty_list(_survivor_head);
220 _survivor_head = NULL;
221 _survivor_tail = NULL;
222 _survivor_length = 0;
223
224 _last_sampled_rs_lengths = 0;
225
226 assert(check_list_empty(false), "just making sure...");
227 }
228
229 bool YoungList::check_list_well_formed() {
230 bool ret = true;
231
232 uint length = 0;
233 HeapRegion* curr = _head;
234 HeapRegion* last = NULL;
235 while (curr != NULL) {
236 if (!curr->is_young()) {
237 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
238 "incorrectly tagged (y: %d, surv: %d)",
239 curr->bottom(), curr->end(),
240 curr->is_young(), curr->is_survivor());
241 ret = false;
242 }
243 ++length;
244 last = curr;
245 curr = curr->get_next_young_region();
246 }
247 ret = ret && (length == _length);
248
249 if (!ret) {
250 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
251 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
252 length, _length);
253 }
254
255 return ret;
256 }
257
258 bool YoungList::check_list_empty(bool check_sample) {
259 bool ret = true;
260
261 if (_length != 0) {
262 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
263 _length);
264 ret = false;
265 }
266 if (check_sample && _last_sampled_rs_lengths != 0) {
267 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
268 ret = false;
269 }
270 if (_head != NULL) {
271 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
272 ret = false;
273 }
274 if (!ret) {
275 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
276 }
277
278 return ret;
279 }
280
281 void
282 YoungList::rs_length_sampling_init() {
283 _sampled_rs_lengths = 0;
284 _curr = _head;
285 }
286
287 bool
288 YoungList::rs_length_sampling_more() {
289 return _curr != NULL;
290 }
291
292 void
293 YoungList::rs_length_sampling_next() {
294 assert( _curr != NULL, "invariant" );
295 size_t rs_length = _curr->rem_set()->occupied();
296
297 _sampled_rs_lengths += rs_length;
298
299 // The current region may not yet have been added to the
300 // incremental collection set (it gets added when it is
301 // retired as the current allocation region).
302 if (_curr->in_collection_set()) {
303 // Update the collection set policy information for this region
304 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
305 }
306
307 _curr = _curr->get_next_young_region();
308 if (_curr == NULL) {
309 _last_sampled_rs_lengths = _sampled_rs_lengths;
310 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
311 }
312 }
313
314 void
315 YoungList::reset_auxilary_lists() {
316 guarantee( is_empty(), "young list should be empty" );
317 assert(check_list_well_formed(), "young list should be well formed");
318
319 // Add survivor regions to SurvRateGroup.
320 _g1h->g1_policy()->note_start_adding_survivor_regions();
321 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
322
323 int young_index_in_cset = 0;
324 for (HeapRegion* curr = _survivor_head;
325 curr != NULL;
326 curr = curr->get_next_young_region()) {
327 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
328
329 // The region is a non-empty survivor so let's add it to
330 // the incremental collection set for the next evacuation
331 // pause.
332 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
333 young_index_in_cset += 1;
334 }
335 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
336 _g1h->g1_policy()->note_stop_adding_survivor_regions();
337
338 _head = _survivor_head;
339 _length = _survivor_length;
340 if (_survivor_head != NULL) {
341 assert(_survivor_tail != NULL, "cause it shouldn't be");
342 assert(_survivor_length > 0, "invariant");
343 _survivor_tail->set_next_young_region(NULL);
344 }
345
346 // Don't clear the survivor list handles until the start of
347 // the next evacuation pause - we need it in order to re-tag
348 // the survivor regions from this evacuation pause as 'young'
349 // at the start of the next.
350
351 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
352
353 assert(check_list_well_formed(), "young list should be well formed");
354 }
355
356 void YoungList::print() {
357 HeapRegion* lists[] = {_head, _survivor_head};
358 const char* names[] = {"YOUNG", "SURVIVOR"};
359
360 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
361 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
362 HeapRegion *curr = lists[list];
363 if (curr == NULL)
364 gclog_or_tty->print_cr(" empty");
365 while (curr != NULL) {
366 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
367 HR_FORMAT_PARAMS(curr),
368 curr->prev_top_at_mark_start(),
369 curr->next_top_at_mark_start(),
370 curr->age_in_surv_rate_group_cond());
371 curr = curr->get_next_young_region();
372 }
373 }
374
375 gclog_or_tty->print_cr("");
376 }
377
378 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
379 {
380 // Claim the right to put the region on the dirty cards region list
381 // by installing a self pointer.
382 HeapRegion* next = hr->get_next_dirty_cards_region();
383 if (next == NULL) {
384 HeapRegion* res = (HeapRegion*)
385 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
386 NULL);
387 if (res == NULL) {
388 HeapRegion* head;
389 do {
390 // Put the region to the dirty cards region list.
391 head = _dirty_cards_region_list;
392 next = (HeapRegion*)
393 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
394 if (next == head) {
395 assert(hr->get_next_dirty_cards_region() == hr,
396 "hr->get_next_dirty_cards_region() != hr");
397 if (next == NULL) {
398 // The last region in the list points to itself.
399 hr->set_next_dirty_cards_region(hr);
400 } else {
401 hr->set_next_dirty_cards_region(next);
402 }
403 }
404 } while (next != head);
405 }
406 }
407 }
408
409 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
410 {
411 HeapRegion* head;
412 HeapRegion* hr;
413 do {
414 head = _dirty_cards_region_list;
415 if (head == NULL) {
416 return NULL;
417 }
418 HeapRegion* new_head = head->get_next_dirty_cards_region();
419 if (head == new_head) {
420 // The last region.
421 new_head = NULL;
422 }
423 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
424 head);
425 } while (hr != head);
426 assert(hr != NULL, "invariant");
427 hr->set_next_dirty_cards_region(NULL);
428 return hr;
429 }
430
431 void G1CollectedHeap::stop_conc_gc_threads() {
432 _cg1r->stop();
433 _cmThread->stop();
434 }
435
436 #ifdef ASSERT
437 // A region is added to the collection set as it is retired
438 // so an address p can point to a region which will be in the
439 // collection set but has not yet been retired. This method
440 // therefore is only accurate during a GC pause after all
441 // regions have been retired. It is used for debugging
442 // to check if an nmethod has references to objects that can
443 // be move during a partial collection. Though it can be
444 // inaccurate, it is sufficient for G1 because the conservative
445 // implementation of is_scavengable() for G1 will indicate that
446 // all nmethods must be scanned during a partial collection.
447 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
448 HeapRegion* hr = heap_region_containing(p);
449 return hr != NULL && hr->in_collection_set();
450 }
451 #endif
452
453 // Returns true if the reference points to an object that
454 // can move in an incremental collection.
455 bool G1CollectedHeap::is_scavengable(const void* p) {
456 G1CollectedHeap* g1h = G1CollectedHeap::heap();
457 G1CollectorPolicy* g1p = g1h->g1_policy();
458 HeapRegion* hr = heap_region_containing(p);
459 if (hr == NULL) {
460 // null
461 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
462 return false;
463 } else {
464 return !hr->isHumongous();
465 }
466 }
467
468 void G1CollectedHeap::check_ct_logs_at_safepoint() {
469 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
470 CardTableModRefBS* ct_bs = g1_barrier_set();
471
472 // Count the dirty cards at the start.
473 CountNonCleanMemRegionClosure count1(this);
474 ct_bs->mod_card_iterate(&count1);
475 int orig_count = count1.n();
476
477 // First clear the logged cards.
478 ClearLoggedCardTableEntryClosure clear;
479 dcqs.set_closure(&clear);
480 dcqs.apply_closure_to_all_completed_buffers();
481 dcqs.iterate_closure_all_threads(false);
482 clear.print_histo();
483
484 // Now ensure that there's no dirty cards.
485 CountNonCleanMemRegionClosure count2(this);
486 ct_bs->mod_card_iterate(&count2);
487 if (count2.n() != 0) {
488 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
489 count2.n(), orig_count);
490 }
491 guarantee(count2.n() == 0, "Card table should be clean.");
492
493 RedirtyLoggedCardTableEntryClosure redirty;
494 JavaThread::dirty_card_queue_set().set_closure(&redirty);
495 dcqs.apply_closure_to_all_completed_buffers();
496 dcqs.iterate_closure_all_threads(false);
497 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
498 clear.calls(), orig_count);
499 guarantee(redirty.calls() == clear.calls(),
500 "Or else mechanism is broken.");
501
502 CountNonCleanMemRegionClosure count3(this);
503 ct_bs->mod_card_iterate(&count3);
504 if (count3.n() != orig_count) {
505 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
506 orig_count, count3.n());
507 guarantee(count3.n() >= orig_count, "Should have restored them all.");
508 }
509
510 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
511 }
512
513 // Private class members.
514
515 G1CollectedHeap* G1CollectedHeap::_g1h;
516
517 // Private methods.
518
519 HeapRegion*
520 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
521 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
522 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
523 if (!_secondary_free_list.is_empty()) {
524 if (G1ConcRegionFreeingVerbose) {
525 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
526 "secondary_free_list has %u entries",
527 _secondary_free_list.length());
528 }
529 // It looks as if there are free regions available on the
530 // secondary_free_list. Let's move them to the free_list and try
531 // again to allocate from it.
532 append_secondary_free_list();
533
534 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
535 "empty we should have moved at least one entry to the free_list");
536 HeapRegion* res = _free_list.remove_region(is_old);
537 if (G1ConcRegionFreeingVerbose) {
538 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
539 "allocated "HR_FORMAT" from secondary_free_list",
540 HR_FORMAT_PARAMS(res));
541 }
542 return res;
543 }
544
545 // Wait here until we get notified either when (a) there are no
546 // more free regions coming or (b) some regions have been moved on
547 // the secondary_free_list.
548 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
549 }
550
551 if (G1ConcRegionFreeingVerbose) {
552 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
553 "could not allocate from secondary_free_list");
554 }
555 return NULL;
556 }
557
558 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
559 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
560 "the only time we use this to allocate a humongous region is "
561 "when we are allocating a single humongous region");
562
563 HeapRegion* res;
564 if (G1StressConcRegionFreeing) {
565 if (!_secondary_free_list.is_empty()) {
566 if (G1ConcRegionFreeingVerbose) {
567 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
568 "forced to look at the secondary_free_list");
569 }
570 res = new_region_try_secondary_free_list(is_old);
571 if (res != NULL) {
572 return res;
573 }
574 }
575 }
576
577 res = _free_list.remove_region(is_old);
578
579 if (res == NULL) {
580 if (G1ConcRegionFreeingVerbose) {
581 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
582 "res == NULL, trying the secondary_free_list");
583 }
584 res = new_region_try_secondary_free_list(is_old);
585 }
586 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
587 // Currently, only attempts to allocate GC alloc regions set
588 // do_expand to true. So, we should only reach here during a
589 // safepoint. If this assumption changes we might have to
590 // reconsider the use of _expand_heap_after_alloc_failure.
591 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
592
593 ergo_verbose1(ErgoHeapSizing,
594 "attempt heap expansion",
595 ergo_format_reason("region allocation request failed")
596 ergo_format_byte("allocation request"),
597 word_size * HeapWordSize);
598 if (expand(word_size * HeapWordSize)) {
599 // Given that expand() succeeded in expanding the heap, and we
600 // always expand the heap by an amount aligned to the heap
601 // region size, the free list should in theory not be empty.
602 // In either case remove_region() will check for NULL.
603 res = _free_list.remove_region(is_old);
604 } else {
605 _expand_heap_after_alloc_failure = false;
606 }
607 }
608 return res;
609 }
610
611 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
612 size_t word_size) {
613 assert(isHumongous(word_size), "word_size should be humongous");
614 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
615
616 uint first = G1_NULL_HRS_INDEX;
617 if (num_regions == 1) {
618 // Only one region to allocate, no need to go through the slower
619 // path. The caller will attempt the expansion if this fails, so
620 // let's not try to expand here too.
621 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
622 if (hr != NULL) {
623 first = hr->hrs_index();
624 } else {
625 first = G1_NULL_HRS_INDEX;
626 }
627 } else {
628 // We can't allocate humongous regions while cleanupComplete() is
629 // running, since some of the regions we find to be empty might not
630 // yet be added to the free list and it is not straightforward to
631 // know which list they are on so that we can remove them. Note
632 // that we only need to do this if we need to allocate more than
633 // one region to satisfy the current humongous allocation
634 // request. If we are only allocating one region we use the common
635 // region allocation code (see above).
636 wait_while_free_regions_coming();
637 append_secondary_free_list_if_not_empty_with_lock();
638
639 if (free_regions() >= num_regions) {
640 first = _hrs.find_contiguous(num_regions);
641 if (first != G1_NULL_HRS_INDEX) {
642 for (uint i = first; i < first + num_regions; ++i) {
643 HeapRegion* hr = region_at(i);
644 assert(hr->is_empty(), "sanity");
645 assert(is_on_master_free_list(hr), "sanity");
646 hr->set_pending_removal(true);
647 }
648 _free_list.remove_all_pending(num_regions);
649 }
650 }
651 }
652 return first;
653 }
654
655 HeapWord*
656 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
657 uint num_regions,
658 size_t word_size) {
659 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
660 assert(isHumongous(word_size), "word_size should be humongous");
661 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
662
663 // Index of last region in the series + 1.
664 uint last = first + num_regions;
665
666 // We need to initialize the region(s) we just discovered. This is
667 // a bit tricky given that it can happen concurrently with
668 // refinement threads refining cards on these regions and
669 // potentially wanting to refine the BOT as they are scanning
670 // those cards (this can happen shortly after a cleanup; see CR
671 // 6991377). So we have to set up the region(s) carefully and in
672 // a specific order.
673
674 // The word size sum of all the regions we will allocate.
675 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
676 assert(word_size <= word_size_sum, "sanity");
677
678 // This will be the "starts humongous" region.
679 HeapRegion* first_hr = region_at(first);
680 // The header of the new object will be placed at the bottom of
681 // the first region.
682 HeapWord* new_obj = first_hr->bottom();
683 // This will be the new end of the first region in the series that
684 // should also match the end of the last region in the series.
685 HeapWord* new_end = new_obj + word_size_sum;
686 // This will be the new top of the first region that will reflect
687 // this allocation.
688 HeapWord* new_top = new_obj + word_size;
689
690 // First, we need to zero the header of the space that we will be
691 // allocating. When we update top further down, some refinement
692 // threads might try to scan the region. By zeroing the header we
693 // ensure that any thread that will try to scan the region will
694 // come across the zero klass word and bail out.
695 //
696 // NOTE: It would not have been correct to have used
697 // CollectedHeap::fill_with_object() and make the space look like
698 // an int array. The thread that is doing the allocation will
699 // later update the object header to a potentially different array
700 // type and, for a very short period of time, the klass and length
701 // fields will be inconsistent. This could cause a refinement
702 // thread to calculate the object size incorrectly.
703 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
704
705 // We will set up the first region as "starts humongous". This
706 // will also update the BOT covering all the regions to reflect
707 // that there is a single object that starts at the bottom of the
708 // first region.
709 first_hr->set_startsHumongous(new_top, new_end);
710
711 // Then, if there are any, we will set up the "continues
712 // humongous" regions.
713 HeapRegion* hr = NULL;
714 for (uint i = first + 1; i < last; ++i) {
715 hr = region_at(i);
716 hr->set_continuesHumongous(first_hr);
717 }
718 // If we have "continues humongous" regions (hr != NULL), then the
719 // end of the last one should match new_end.
720 assert(hr == NULL || hr->end() == new_end, "sanity");
721
722 // Up to this point no concurrent thread would have been able to
723 // do any scanning on any region in this series. All the top
724 // fields still point to bottom, so the intersection between
725 // [bottom,top] and [card_start,card_end] will be empty. Before we
726 // update the top fields, we'll do a storestore to make sure that
727 // no thread sees the update to top before the zeroing of the
728 // object header and the BOT initialization.
729 OrderAccess::storestore();
730
731 // Now that the BOT and the object header have been initialized,
732 // we can update top of the "starts humongous" region.
733 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
734 "new_top should be in this region");
735 first_hr->set_top(new_top);
736 if (_hr_printer.is_active()) {
737 HeapWord* bottom = first_hr->bottom();
738 HeapWord* end = first_hr->orig_end();
739 if ((first + 1) == last) {
740 // the series has a single humongous region
741 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
742 } else {
743 // the series has more than one humongous regions
744 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
745 }
746 }
747
748 // Now, we will update the top fields of the "continues humongous"
749 // regions. The reason we need to do this is that, otherwise,
750 // these regions would look empty and this will confuse parts of
751 // G1. For example, the code that looks for a consecutive number
752 // of empty regions will consider them empty and try to
753 // re-allocate them. We can extend is_empty() to also include
754 // !continuesHumongous(), but it is easier to just update the top
755 // fields here. The way we set top for all regions (i.e., top ==
756 // end for all regions but the last one, top == new_top for the
757 // last one) is actually used when we will free up the humongous
758 // region in free_humongous_region().
759 hr = NULL;
760 for (uint i = first + 1; i < last; ++i) {
761 hr = region_at(i);
762 if ((i + 1) == last) {
763 // last continues humongous region
764 assert(hr->bottom() < new_top && new_top <= hr->end(),
765 "new_top should fall on this region");
766 hr->set_top(new_top);
767 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
768 } else {
769 // not last one
770 assert(new_top > hr->end(), "new_top should be above this region");
771 hr->set_top(hr->end());
772 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
773 }
774 }
775 // If we have continues humongous regions (hr != NULL), then the
776 // end of the last one should match new_end and its top should
777 // match new_top.
778 assert(hr == NULL ||
779 (hr->end() == new_end && hr->top() == new_top), "sanity");
780
781 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
782 _summary_bytes_used += first_hr->used();
783 _humongous_set.add(first_hr);
784
785 return new_obj;
786 }
787
788 // If could fit into free regions w/o expansion, try.
789 // Otherwise, if can expand, do so.
790 // Otherwise, if using ex regions might help, try with ex given back.
791 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
792 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
793
794 verify_region_sets_optional();
795
796 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
797 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
798 uint x_num = expansion_regions();
799 uint fs = _hrs.free_suffix();
800 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
801 if (first == G1_NULL_HRS_INDEX) {
802 // The only thing we can do now is attempt expansion.
803 if (fs + x_num >= num_regions) {
804 // If the number of regions we're trying to allocate for this
805 // object is at most the number of regions in the free suffix,
806 // then the call to humongous_obj_allocate_find_first() above
807 // should have succeeded and we wouldn't be here.
808 //
809 // We should only be trying to expand when the free suffix is
810 // not sufficient for the object _and_ we have some expansion
811 // room available.
812 assert(num_regions > fs, "earlier allocation should have succeeded");
813
814 ergo_verbose1(ErgoHeapSizing,
815 "attempt heap expansion",
816 ergo_format_reason("humongous allocation request failed")
817 ergo_format_byte("allocation request"),
818 word_size * HeapWordSize);
819 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
820 // Even though the heap was expanded, it might not have
821 // reached the desired size. So, we cannot assume that the
822 // allocation will succeed.
823 first = humongous_obj_allocate_find_first(num_regions, word_size);
824 }
825 }
826 }
827
828 HeapWord* result = NULL;
829 if (first != G1_NULL_HRS_INDEX) {
830 result =
831 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
832 assert(result != NULL, "it should always return a valid result");
833
834 // A successful humongous object allocation changes the used space
835 // information of the old generation so we need to recalculate the
836 // sizes and update the jstat counters here.
837 g1mm()->update_sizes();
838 }
839
840 verify_region_sets_optional();
841
842 return result;
843 }
844
845 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
846 assert_heap_not_locked_and_not_at_safepoint();
847 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
848
849 unsigned int dummy_gc_count_before;
850 int dummy_gclocker_retry_count = 0;
851 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
852 }
853
854 HeapWord*
855 G1CollectedHeap::mem_allocate(size_t word_size,
856 bool* gc_overhead_limit_was_exceeded) {
857 assert_heap_not_locked_and_not_at_safepoint();
858
859 // Loop until the allocation is satisfied, or unsatisfied after GC.
860 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
861 unsigned int gc_count_before;
862
863 HeapWord* result = NULL;
864 if (!isHumongous(word_size)) {
865 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
866 } else {
867 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
868 }
869 if (result != NULL) {
870 return result;
871 }
872
873 // Create the garbage collection operation...
874 VM_G1CollectForAllocation op(gc_count_before, word_size);
875 // ...and get the VM thread to execute it.
876 VMThread::execute(&op);
877
878 if (op.prologue_succeeded() && op.pause_succeeded()) {
879 // If the operation was successful we'll return the result even
880 // if it is NULL. If the allocation attempt failed immediately
881 // after a Full GC, it's unlikely we'll be able to allocate now.
882 HeapWord* result = op.result();
883 if (result != NULL && !isHumongous(word_size)) {
884 // Allocations that take place on VM operations do not do any
885 // card dirtying and we have to do it here. We only have to do
886 // this for non-humongous allocations, though.
887 dirty_young_block(result, word_size);
888 }
889 return result;
890 } else {
891 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
892 return NULL;
893 }
894 assert(op.result() == NULL,
895 "the result should be NULL if the VM op did not succeed");
896 }
897
898 // Give a warning if we seem to be looping forever.
899 if ((QueuedAllocationWarningCount > 0) &&
900 (try_count % QueuedAllocationWarningCount == 0)) {
901 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
902 }
903 }
904
905 ShouldNotReachHere();
906 return NULL;
907 }
908
909 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
910 unsigned int *gc_count_before_ret,
911 int* gclocker_retry_count_ret) {
912 // Make sure you read the note in attempt_allocation_humongous().
913
914 assert_heap_not_locked_and_not_at_safepoint();
915 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
916 "be called for humongous allocation requests");
917
918 // We should only get here after the first-level allocation attempt
919 // (attempt_allocation()) failed to allocate.
920
921 // We will loop until a) we manage to successfully perform the
922 // allocation or b) we successfully schedule a collection which
923 // fails to perform the allocation. b) is the only case when we'll
924 // return NULL.
925 HeapWord* result = NULL;
926 for (int try_count = 1; /* we'll return */; try_count += 1) {
927 bool should_try_gc;
928 unsigned int gc_count_before;
929
930 {
931 MutexLockerEx x(Heap_lock);
932
933 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
934 false /* bot_updates */);
935 if (result != NULL) {
936 return result;
937 }
938
939 // If we reach here, attempt_allocation_locked() above failed to
940 // allocate a new region. So the mutator alloc region should be NULL.
941 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
942
943 if (GC_locker::is_active_and_needs_gc()) {
944 if (g1_policy()->can_expand_young_list()) {
945 // No need for an ergo verbose message here,
946 // can_expand_young_list() does this when it returns true.
947 result = _mutator_alloc_region.attempt_allocation_force(word_size,
948 false /* bot_updates */);
949 if (result != NULL) {
950 return result;
951 }
952 }
953 should_try_gc = false;
954 } else {
955 // The GCLocker may not be active but the GCLocker initiated
956 // GC may not yet have been performed (GCLocker::needs_gc()
957 // returns true). In this case we do not try this GC and
958 // wait until the GCLocker initiated GC is performed, and
959 // then retry the allocation.
960 if (GC_locker::needs_gc()) {
961 should_try_gc = false;
962 } else {
963 // Read the GC count while still holding the Heap_lock.
964 gc_count_before = total_collections();
965 should_try_gc = true;
966 }
967 }
968 }
969
970 if (should_try_gc) {
971 bool succeeded;
972 result = do_collection_pause(word_size, gc_count_before, &succeeded,
973 GCCause::_g1_inc_collection_pause);
974 if (result != NULL) {
975 assert(succeeded, "only way to get back a non-NULL result");
976 return result;
977 }
978
979 if (succeeded) {
980 // If we get here we successfully scheduled a collection which
981 // failed to allocate. No point in trying to allocate
982 // further. We'll just return NULL.
983 MutexLockerEx x(Heap_lock);
984 *gc_count_before_ret = total_collections();
985 return NULL;
986 }
987 } else {
988 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
989 MutexLockerEx x(Heap_lock);
990 *gc_count_before_ret = total_collections();
991 return NULL;
992 }
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 (*gclocker_retry_count_ret) += 1;
998 }
999
1000 // We can reach here if we were unsuccessful in scheduling a
1001 // collection (because another thread beat us to it) or if we were
1002 // stalled due to the GC locker. In either can we should retry the
1003 // allocation attempt in case another thread successfully
1004 // performed a collection and reclaimed enough space. We do the
1005 // first attempt (without holding the Heap_lock) here and the
1006 // follow-on attempt will be at the start of the next loop
1007 // iteration (after taking the Heap_lock).
1008 result = _mutator_alloc_region.attempt_allocation(word_size,
1009 false /* bot_updates */);
1010 if (result != NULL) {
1011 return result;
1012 }
1013
1014 // Give a warning if we seem to be looping forever.
1015 if ((QueuedAllocationWarningCount > 0) &&
1016 (try_count % QueuedAllocationWarningCount == 0)) {
1017 warning("G1CollectedHeap::attempt_allocation_slow() "
1018 "retries %d times", try_count);
1019 }
1020 }
1021
1022 ShouldNotReachHere();
1023 return NULL;
1024 }
1025
1026 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1027 unsigned int * gc_count_before_ret,
1028 int* gclocker_retry_count_ret) {
1029 // The structure of this method has a lot of similarities to
1030 // attempt_allocation_slow(). The reason these two were not merged
1031 // into a single one is that such a method would require several "if
1032 // allocation is not humongous do this, otherwise do that"
1033 // conditional paths which would obscure its flow. In fact, an early
1034 // version of this code did use a unified method which was harder to
1035 // follow and, as a result, it had subtle bugs that were hard to
1036 // track down. So keeping these two methods separate allows each to
1037 // be more readable. It will be good to keep these two in sync as
1038 // much as possible.
1039
1040 assert_heap_not_locked_and_not_at_safepoint();
1041 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1042 "should only be called for humongous allocations");
1043
1044 // Humongous objects can exhaust the heap quickly, so we should check if we
1045 // need to start a marking cycle at each humongous object allocation. We do
1046 // the check before we do the actual allocation. The reason for doing it
1047 // before the allocation is that we avoid having to keep track of the newly
1048 // allocated memory while we do a GC.
1049 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1050 word_size)) {
1051 collect(GCCause::_g1_humongous_allocation);
1052 }
1053
1054 // We will loop until a) we manage to successfully perform the
1055 // allocation or b) we successfully schedule a collection which
1056 // fails to perform the allocation. b) is the only case when we'll
1057 // return NULL.
1058 HeapWord* result = NULL;
1059 for (int try_count = 1; /* we'll return */; try_count += 1) {
1060 bool should_try_gc;
1061 unsigned int gc_count_before;
1062
1063 {
1064 MutexLockerEx x(Heap_lock);
1065
1066 // Given that humongous objects are not allocated in young
1067 // regions, we'll first try to do the allocation without doing a
1068 // collection hoping that there's enough space in the heap.
1069 result = humongous_obj_allocate(word_size);
1070 if (result != NULL) {
1071 return result;
1072 }
1073
1074 if (GC_locker::is_active_and_needs_gc()) {
1075 should_try_gc = false;
1076 } else {
1077 // The GCLocker may not be active but the GCLocker initiated
1078 // GC may not yet have been performed (GCLocker::needs_gc()
1079 // returns true). In this case we do not try this GC and
1080 // wait until the GCLocker initiated GC is performed, and
1081 // then retry the allocation.
1082 if (GC_locker::needs_gc()) {
1083 should_try_gc = false;
1084 } else {
1085 // Read the GC count while still holding the Heap_lock.
1086 gc_count_before = total_collections();
1087 should_try_gc = true;
1088 }
1089 }
1090 }
1091
1092 if (should_try_gc) {
1093 // If we failed to allocate the humongous object, we should try to
1094 // do a collection pause (if we're allowed) in case it reclaims
1095 // enough space for the allocation to succeed after the pause.
1096
1097 bool succeeded;
1098 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1099 GCCause::_g1_humongous_allocation);
1100 if (result != NULL) {
1101 assert(succeeded, "only way to get back a non-NULL result");
1102 return result;
1103 }
1104
1105 if (succeeded) {
1106 // If we get here we successfully scheduled a collection which
1107 // failed to allocate. No point in trying to allocate
1108 // further. We'll just return NULL.
1109 MutexLockerEx x(Heap_lock);
1110 *gc_count_before_ret = total_collections();
1111 return NULL;
1112 }
1113 } else {
1114 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1115 MutexLockerEx x(Heap_lock);
1116 *gc_count_before_ret = total_collections();
1117 return NULL;
1118 }
1119 // The GCLocker is either active or the GCLocker initiated
1120 // GC has not yet been performed. Stall until it is and
1121 // then retry the allocation.
1122 GC_locker::stall_until_clear();
1123 (*gclocker_retry_count_ret) += 1;
1124 }
1125
1126 // We can reach here if we were unsuccessful in scheduling a
1127 // collection (because another thread beat us to it) or if we were
1128 // stalled due to the GC locker. In either can we should retry the
1129 // allocation attempt in case another thread successfully
1130 // performed a collection and reclaimed enough space. Give a
1131 // warning if we seem to be looping forever.
1132
1133 if ((QueuedAllocationWarningCount > 0) &&
1134 (try_count % QueuedAllocationWarningCount == 0)) {
1135 warning("G1CollectedHeap::attempt_allocation_humongous() "
1136 "retries %d times", try_count);
1137 }
1138 }
1139
1140 ShouldNotReachHere();
1141 return NULL;
1142 }
1143
1144 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1145 bool expect_null_mutator_alloc_region) {
1146 assert_at_safepoint(true /* should_be_vm_thread */);
1147 assert(_mutator_alloc_region.get() == NULL ||
1148 !expect_null_mutator_alloc_region,
1149 "the current alloc region was unexpectedly found to be non-NULL");
1150
1151 if (!isHumongous(word_size)) {
1152 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1153 false /* bot_updates */);
1154 } else {
1155 HeapWord* result = humongous_obj_allocate(word_size);
1156 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1157 g1_policy()->set_initiate_conc_mark_if_possible();
1158 }
1159 return result;
1160 }
1161
1162 ShouldNotReachHere();
1163 }
1164
1165 class PostMCRemSetClearClosure: public HeapRegionClosure {
1166 G1CollectedHeap* _g1h;
1167 ModRefBarrierSet* _mr_bs;
1168 public:
1169 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1170 _g1h(g1h), _mr_bs(mr_bs) {}
1171
1172 bool doHeapRegion(HeapRegion* r) {
1173 HeapRegionRemSet* hrrs = r->rem_set();
1174
1175 if (r->continuesHumongous()) {
1176 // We'll assert that the strong code root list and RSet is empty
1177 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1178 assert(hrrs->occupied() == 0, "RSet should be empty");
1179 return false;
1180 }
1181
1182 _g1h->reset_gc_time_stamps(r);
1183 hrrs->clear();
1184 // You might think here that we could clear just the cards
1185 // corresponding to the used region. But no: if we leave a dirty card
1186 // in a region we might allocate into, then it would prevent that card
1187 // from being enqueued, and cause it to be missed.
1188 // Re: the performance cost: we shouldn't be doing full GC anyway!
1189 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1190
1191 return false;
1192 }
1193 };
1194
1195 void G1CollectedHeap::clear_rsets_post_compaction() {
1196 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1197 heap_region_iterate(&rs_clear);
1198 }
1199
1200 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1201 G1CollectedHeap* _g1h;
1202 UpdateRSOopClosure _cl;
1203 int _worker_i;
1204 public:
1205 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1206 _cl(g1->g1_rem_set(), worker_i),
1207 _worker_i(worker_i),
1208 _g1h(g1)
1209 { }
1210
1211 bool doHeapRegion(HeapRegion* r) {
1212 if (!r->continuesHumongous()) {
1213 _cl.set_from(r);
1214 r->oop_iterate(&_cl);
1215 }
1216 return false;
1217 }
1218 };
1219
1220 class ParRebuildRSTask: public AbstractGangTask {
1221 G1CollectedHeap* _g1;
1222 public:
1223 ParRebuildRSTask(G1CollectedHeap* g1)
1224 : AbstractGangTask("ParRebuildRSTask"),
1225 _g1(g1)
1226 { }
1227
1228 void work(uint worker_id) {
1229 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1230 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1231 _g1->workers()->active_workers(),
1232 HeapRegion::RebuildRSClaimValue);
1233 }
1234 };
1235
1236 class PostCompactionPrinterClosure: public HeapRegionClosure {
1237 private:
1238 G1HRPrinter* _hr_printer;
1239 public:
1240 bool doHeapRegion(HeapRegion* hr) {
1241 assert(!hr->is_young(), "not expecting to find young regions");
1242 // We only generate output for non-empty regions.
1243 if (!hr->is_empty()) {
1244 if (!hr->isHumongous()) {
1245 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1246 } else if (hr->startsHumongous()) {
1247 if (hr->region_num() == 1) {
1248 // single humongous region
1249 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1250 } else {
1251 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1252 }
1253 } else {
1254 assert(hr->continuesHumongous(), "only way to get here");
1255 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1256 }
1257 }
1258 return false;
1259 }
1260
1261 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1262 : _hr_printer(hr_printer) { }
1263 };
1264
1265 void G1CollectedHeap::print_hrs_post_compaction() {
1266 PostCompactionPrinterClosure cl(hr_printer());
1267 heap_region_iterate(&cl);
1268 }
1269
1270 bool G1CollectedHeap::do_collection(bool explicit_gc,
1271 bool clear_all_soft_refs,
1272 size_t word_size) {
1273 assert_at_safepoint(true /* should_be_vm_thread */);
1274
1275 if (GC_locker::check_active_before_gc()) {
1276 return false;
1277 }
1278
1279 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1280 gc_timer->register_gc_start();
1281
1282 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1283 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1284
1285 SvcGCMarker sgcm(SvcGCMarker::FULL);
1286 ResourceMark rm;
1287
1288 print_heap_before_gc();
1289 trace_heap_before_gc(gc_tracer);
1290
1291 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1292
1293 verify_region_sets_optional();
1294
1295 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1296 collector_policy()->should_clear_all_soft_refs();
1297
1298 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1299
1300 {
1301 IsGCActiveMark x;
1302
1303 // Timing
1304 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1305 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1306 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1307
1308 {
1309 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1310 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1311 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1312
1313 double start = os::elapsedTime();
1314 g1_policy()->record_full_collection_start();
1315
1316 // Note: When we have a more flexible GC logging framework that
1317 // allows us to add optional attributes to a GC log record we
1318 // could consider timing and reporting how long we wait in the
1319 // following two methods.
1320 wait_while_free_regions_coming();
1321 // If we start the compaction before the CM threads finish
1322 // scanning the root regions we might trip them over as we'll
1323 // be moving objects / updating references. So let's wait until
1324 // they are done. By telling them to abort, they should complete
1325 // early.
1326 _cm->root_regions()->abort();
1327 _cm->root_regions()->wait_until_scan_finished();
1328 append_secondary_free_list_if_not_empty_with_lock();
1329
1330 gc_prologue(true);
1331 increment_total_collections(true /* full gc */);
1332 increment_old_marking_cycles_started();
1333
1334 assert(used() == recalculate_used(), "Should be equal");
1335
1336 verify_before_gc();
1337
1338 pre_full_gc_dump(gc_timer);
1339
1340 COMPILER2_PRESENT(DerivedPointerTable::clear());
1341
1342 // Disable discovery and empty the discovered lists
1343 // for the CM ref processor.
1344 ref_processor_cm()->disable_discovery();
1345 ref_processor_cm()->abandon_partial_discovery();
1346 ref_processor_cm()->verify_no_references_recorded();
1347
1348 // Abandon current iterations of concurrent marking and concurrent
1349 // refinement, if any are in progress. We have to do this before
1350 // wait_until_scan_finished() below.
1351 concurrent_mark()->abort();
1352
1353 // Make sure we'll choose a new allocation region afterwards.
1354 release_mutator_alloc_region();
1355 abandon_gc_alloc_regions();
1356 g1_rem_set()->cleanupHRRS();
1357
1358 // We should call this after we retire any currently active alloc
1359 // regions so that all the ALLOC / RETIRE events are generated
1360 // before the start GC event.
1361 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1362
1363 // We may have added regions to the current incremental collection
1364 // set between the last GC or pause and now. We need to clear the
1365 // incremental collection set and then start rebuilding it afresh
1366 // after this full GC.
1367 abandon_collection_set(g1_policy()->inc_cset_head());
1368 g1_policy()->clear_incremental_cset();
1369 g1_policy()->stop_incremental_cset_building();
1370
1371 tear_down_region_sets(false /* free_list_only */);
1372 g1_policy()->set_gcs_are_young(true);
1373
1374 // See the comments in g1CollectedHeap.hpp and
1375 // G1CollectedHeap::ref_processing_init() about
1376 // how reference processing currently works in G1.
1377
1378 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1379 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1380
1381 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1382 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1383
1384 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1385 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1386
1387 // Do collection work
1388 {
1389 HandleMark hm; // Discard invalid handles created during gc
1390 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1391 }
1392
1393 assert(free_regions() == 0, "we should not have added any free regions");
1394 rebuild_region_sets(false /* free_list_only */);
1395
1396 // Enqueue any discovered reference objects that have
1397 // not been removed from the discovered lists.
1398 ref_processor_stw()->enqueue_discovered_references();
1399
1400 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1401
1402 MemoryService::track_memory_usage();
1403
1404 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1405 ref_processor_stw()->verify_no_references_recorded();
1406
1407 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1408 ClassLoaderDataGraph::purge();
1409 MetaspaceAux::verify_metrics();
1410
1411 // Note: since we've just done a full GC, concurrent
1412 // marking is no longer active. Therefore we need not
1413 // re-enable reference discovery for the CM ref processor.
1414 // That will be done at the start of the next marking cycle.
1415 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1416 ref_processor_cm()->verify_no_references_recorded();
1417
1418 reset_gc_time_stamp();
1419 // Since everything potentially moved, we will clear all remembered
1420 // sets, and clear all cards. Later we will rebuild remembered
1421 // sets. We will also reset the GC time stamps of the regions.
1422 clear_rsets_post_compaction();
1423 check_gc_time_stamps();
1424
1425 // Resize the heap if necessary.
1426 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1427
1428 if (_hr_printer.is_active()) {
1429 // We should do this after we potentially resize the heap so
1430 // that all the COMMIT / UNCOMMIT events are generated before
1431 // the end GC event.
1432
1433 print_hrs_post_compaction();
1434 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1435 }
1436
1437 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1438 if (hot_card_cache->use_cache()) {
1439 hot_card_cache->reset_card_counts();
1440 hot_card_cache->reset_hot_cache();
1441 }
1442
1443 // Rebuild remembered sets of all regions.
1444 if (G1CollectedHeap::use_parallel_gc_threads()) {
1445 uint n_workers =
1446 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1447 workers()->active_workers(),
1448 Threads::number_of_non_daemon_threads());
1449 assert(UseDynamicNumberOfGCThreads ||
1450 n_workers == workers()->total_workers(),
1451 "If not dynamic should be using all the workers");
1452 workers()->set_active_workers(n_workers);
1453 // Set parallel threads in the heap (_n_par_threads) only
1454 // before a parallel phase and always reset it to 0 after
1455 // the phase so that the number of parallel threads does
1456 // no get carried forward to a serial phase where there
1457 // may be code that is "possibly_parallel".
1458 set_par_threads(n_workers);
1459
1460 ParRebuildRSTask rebuild_rs_task(this);
1461 assert(check_heap_region_claim_values(
1462 HeapRegion::InitialClaimValue), "sanity check");
1463 assert(UseDynamicNumberOfGCThreads ||
1464 workers()->active_workers() == workers()->total_workers(),
1465 "Unless dynamic should use total workers");
1466 // Use the most recent number of active workers
1467 assert(workers()->active_workers() > 0,
1468 "Active workers not properly set");
1469 set_par_threads(workers()->active_workers());
1470 workers()->run_task(&rebuild_rs_task);
1471 set_par_threads(0);
1472 assert(check_heap_region_claim_values(
1473 HeapRegion::RebuildRSClaimValue), "sanity check");
1474 reset_heap_region_claim_values();
1475 } else {
1476 RebuildRSOutOfRegionClosure rebuild_rs(this);
1477 heap_region_iterate(&rebuild_rs);
1478 }
1479
1480 // Rebuild the strong code root lists for each region
1481 rebuild_strong_code_roots();
1482
1483 if (true) { // FIXME
1484 MetaspaceGC::compute_new_size();
1485 }
1486
1487 #ifdef TRACESPINNING
1488 ParallelTaskTerminator::print_termination_counts();
1489 #endif
1490
1491 // Discard all rset updates
1492 JavaThread::dirty_card_queue_set().abandon_logs();
1493 assert(!G1DeferredRSUpdate
1494 || (G1DeferredRSUpdate &&
1495 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1496
1497 _young_list->reset_sampled_info();
1498 // At this point there should be no regions in the
1499 // entire heap tagged as young.
1500 assert(check_young_list_empty(true /* check_heap */),
1501 "young list should be empty at this point");
1502
1503 // Update the number of full collections that have been completed.
1504 increment_old_marking_cycles_completed(false /* concurrent */);
1505
1506 _hrs.verify_optional();
1507 verify_region_sets_optional();
1508
1509 verify_after_gc();
1510
1511 // Start a new incremental collection set for the next pause
1512 assert(g1_policy()->collection_set() == NULL, "must be");
1513 g1_policy()->start_incremental_cset_building();
1514
1515 clear_cset_fast_test();
1516
1517 init_mutator_alloc_region();
1518
1519 double end = os::elapsedTime();
1520 g1_policy()->record_full_collection_end();
1521
1522 if (G1Log::fine()) {
1523 g1_policy()->print_heap_transition();
1524 }
1525
1526 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1527 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1528 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1529 // before any GC notifications are raised.
1530 g1mm()->update_sizes();
1531
1532 gc_epilogue(true);
1533 }
1534
1535 if (G1Log::finer()) {
1536 g1_policy()->print_detailed_heap_transition(true /* full */);
1537 }
1538
1539 print_heap_after_gc();
1540 trace_heap_after_gc(gc_tracer);
1541
1542 post_full_gc_dump(gc_timer);
1543
1544 gc_timer->register_gc_end();
1545 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1546 }
1547
1548 return true;
1549 }
1550
1551 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1552 // do_collection() will return whether it succeeded in performing
1553 // the GC. Currently, there is no facility on the
1554 // do_full_collection() API to notify the caller than the collection
1555 // did not succeed (e.g., because it was locked out by the GC
1556 // locker). So, right now, we'll ignore the return value.
1557 bool dummy = do_collection(true, /* explicit_gc */
1558 clear_all_soft_refs,
1559 0 /* word_size */);
1560 }
1561
1562 // This code is mostly copied from TenuredGeneration.
1563 void
1564 G1CollectedHeap::
1565 resize_if_necessary_after_full_collection(size_t word_size) {
1566 // Include the current allocation, if any, and bytes that will be
1567 // pre-allocated to support collections, as "used".
1568 const size_t used_after_gc = used();
1569 const size_t capacity_after_gc = capacity();
1570 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1571
1572 // This is enforced in arguments.cpp.
1573 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1574 "otherwise the code below doesn't make sense");
1575
1576 // We don't have floating point command-line arguments
1577 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1578 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1579 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1580 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1581
1582 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1583 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1584
1585 // We have to be careful here as these two calculations can overflow
1586 // 32-bit size_t's.
1587 double used_after_gc_d = (double) used_after_gc;
1588 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1589 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1590
1591 // Let's make sure that they are both under the max heap size, which
1592 // by default will make them fit into a size_t.
1593 double desired_capacity_upper_bound = (double) max_heap_size;
1594 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1595 desired_capacity_upper_bound);
1596 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1597 desired_capacity_upper_bound);
1598
1599 // We can now safely turn them into size_t's.
1600 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1601 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1602
1603 // This assert only makes sense here, before we adjust them
1604 // with respect to the min and max heap size.
1605 assert(minimum_desired_capacity <= maximum_desired_capacity,
1606 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1607 "maximum_desired_capacity = "SIZE_FORMAT,
1608 minimum_desired_capacity, maximum_desired_capacity));
1609
1610 // Should not be greater than the heap max size. No need to adjust
1611 // it with respect to the heap min size as it's a lower bound (i.e.,
1612 // we'll try to make the capacity larger than it, not smaller).
1613 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1614 // Should not be less than the heap min size. No need to adjust it
1615 // with respect to the heap max size as it's an upper bound (i.e.,
1616 // we'll try to make the capacity smaller than it, not greater).
1617 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1618
1619 if (capacity_after_gc < minimum_desired_capacity) {
1620 // Don't expand unless it's significant
1621 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1622 ergo_verbose4(ErgoHeapSizing,
1623 "attempt heap expansion",
1624 ergo_format_reason("capacity lower than "
1625 "min desired capacity after Full GC")
1626 ergo_format_byte("capacity")
1627 ergo_format_byte("occupancy")
1628 ergo_format_byte_perc("min desired capacity"),
1629 capacity_after_gc, used_after_gc,
1630 minimum_desired_capacity, (double) MinHeapFreeRatio);
1631 expand(expand_bytes);
1632
1633 // No expansion, now see if we want to shrink
1634 } else if (capacity_after_gc > maximum_desired_capacity) {
1635 // Capacity too large, compute shrinking size
1636 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1637 ergo_verbose4(ErgoHeapSizing,
1638 "attempt heap shrinking",
1639 ergo_format_reason("capacity higher than "
1640 "max desired capacity after Full GC")
1641 ergo_format_byte("capacity")
1642 ergo_format_byte("occupancy")
1643 ergo_format_byte_perc("max desired capacity"),
1644 capacity_after_gc, used_after_gc,
1645 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1646 shrink(shrink_bytes);
1647 }
1648 }
1649
1650
1651 HeapWord*
1652 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1653 bool* succeeded) {
1654 assert_at_safepoint(true /* should_be_vm_thread */);
1655
1656 *succeeded = true;
1657 // Let's attempt the allocation first.
1658 HeapWord* result =
1659 attempt_allocation_at_safepoint(word_size,
1660 false /* expect_null_mutator_alloc_region */);
1661 if (result != NULL) {
1662 assert(*succeeded, "sanity");
1663 return result;
1664 }
1665
1666 // In a G1 heap, we're supposed to keep allocation from failing by
1667 // incremental pauses. Therefore, at least for now, we'll favor
1668 // expansion over collection. (This might change in the future if we can
1669 // do something smarter than full collection to satisfy a failed alloc.)
1670 result = expand_and_allocate(word_size);
1671 if (result != NULL) {
1672 assert(*succeeded, "sanity");
1673 return result;
1674 }
1675
1676 // Expansion didn't work, we'll try to do a Full GC.
1677 bool gc_succeeded = do_collection(false, /* explicit_gc */
1678 false, /* clear_all_soft_refs */
1679 word_size);
1680 if (!gc_succeeded) {
1681 *succeeded = false;
1682 return NULL;
1683 }
1684
1685 // Retry the allocation
1686 result = attempt_allocation_at_safepoint(word_size,
1687 true /* expect_null_mutator_alloc_region */);
1688 if (result != NULL) {
1689 assert(*succeeded, "sanity");
1690 return result;
1691 }
1692
1693 // Then, try a Full GC that will collect all soft references.
1694 gc_succeeded = do_collection(false, /* explicit_gc */
1695 true, /* clear_all_soft_refs */
1696 word_size);
1697 if (!gc_succeeded) {
1698 *succeeded = false;
1699 return NULL;
1700 }
1701
1702 // Retry the allocation once more
1703 result = attempt_allocation_at_safepoint(word_size,
1704 true /* expect_null_mutator_alloc_region */);
1705 if (result != NULL) {
1706 assert(*succeeded, "sanity");
1707 return result;
1708 }
1709
1710 assert(!collector_policy()->should_clear_all_soft_refs(),
1711 "Flag should have been handled and cleared prior to this point");
1712
1713 // What else? We might try synchronous finalization later. If the total
1714 // space available is large enough for the allocation, then a more
1715 // complete compaction phase than we've tried so far might be
1716 // appropriate.
1717 assert(*succeeded, "sanity");
1718 return NULL;
1719 }
1720
1721 // Attempting to expand the heap sufficiently
1722 // to support an allocation of the given "word_size". If
1723 // successful, perform the allocation and return the address of the
1724 // allocated block, or else "NULL".
1725
1726 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1727 assert_at_safepoint(true /* should_be_vm_thread */);
1728
1729 verify_region_sets_optional();
1730
1731 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1732 ergo_verbose1(ErgoHeapSizing,
1733 "attempt heap expansion",
1734 ergo_format_reason("allocation request failed")
1735 ergo_format_byte("allocation request"),
1736 word_size * HeapWordSize);
1737 if (expand(expand_bytes)) {
1738 _hrs.verify_optional();
1739 verify_region_sets_optional();
1740 return attempt_allocation_at_safepoint(word_size,
1741 false /* expect_null_mutator_alloc_region */);
1742 }
1743 return NULL;
1744 }
1745
1746 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1747 HeapWord* new_end) {
1748 assert(old_end != new_end, "don't call this otherwise");
1749 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1750
1751 // Update the committed mem region.
1752 _g1_committed.set_end(new_end);
1753 // Tell the card table about the update.
1754 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1755 // Tell the BOT about the update.
1756 _bot_shared->resize(_g1_committed.word_size());
1757 // Tell the hot card cache about the update
1758 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1759 }
1760
1761 bool G1CollectedHeap::expand(size_t expand_bytes) {
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 if (_g1_storage.uncommitted_size() == 0) {
1772 ergo_verbose0(ErgoHeapSizing,
1773 "did not expand the heap",
1774 ergo_format_reason("heap already fully expanded"));
1775 return false;
1776 }
1777
1778 // First commit the memory.
1779 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1780 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1781 if (successful) {
1782 // Then propagate this update to the necessary data structures.
1783 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1784 update_committed_space(old_end, new_end);
1785
1786 FreeRegionList expansion_list("Local Expansion List");
1787 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1788 assert(mr.start() == old_end, "post-condition");
1789 // mr might be a smaller region than what was requested if
1790 // expand_by() was unable to allocate the HeapRegion instances
1791 assert(mr.end() <= new_end, "post-condition");
1792
1793 size_t actual_expand_bytes = mr.byte_size();
1794 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1795 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1796 "post-condition");
1797 if (actual_expand_bytes < aligned_expand_bytes) {
1798 // We could not expand _hrs to the desired size. In this case we
1799 // need to shrink the committed space accordingly.
1800 assert(mr.end() < new_end, "invariant");
1801
1802 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1803 // First uncommit the memory.
1804 _g1_storage.shrink_by(diff_bytes);
1805 // Then propagate this update to the necessary data structures.
1806 update_committed_space(new_end, mr.end());
1807 }
1808 _free_list.add_as_tail(&expansion_list);
1809
1810 if (_hr_printer.is_active()) {
1811 HeapWord* curr = mr.start();
1812 while (curr < mr.end()) {
1813 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1814 _hr_printer.commit(curr, curr_end);
1815 curr = curr_end;
1816 }
1817 assert(curr == mr.end(), "post-condition");
1818 }
1819 g1_policy()->record_new_heap_size(n_regions());
1820 } else {
1821 ergo_verbose0(ErgoHeapSizing,
1822 "did not expand the heap",
1823 ergo_format_reason("heap expansion operation failed"));
1824 // The expansion of the virtual storage space was unsuccessful.
1825 // Let's see if it was because we ran out of swap.
1826 if (G1ExitOnExpansionFailure &&
1827 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1828 // We had head room...
1829 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1830 }
1831 }
1832 return successful;
1833 }
1834
1835 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1836 size_t aligned_shrink_bytes =
1837 ReservedSpace::page_align_size_down(shrink_bytes);
1838 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1839 HeapRegion::GrainBytes);
1840 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1841
1842 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1843 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1844 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1845
1846 ergo_verbose3(ErgoHeapSizing,
1847 "shrink the heap",
1848 ergo_format_byte("requested shrinking amount")
1849 ergo_format_byte("aligned shrinking amount")
1850 ergo_format_byte("attempted shrinking amount"),
1851 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1852 if (num_regions_removed > 0) {
1853 _g1_storage.shrink_by(shrunk_bytes);
1854 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1855
1856 if (_hr_printer.is_active()) {
1857 HeapWord* curr = old_end;
1858 while (curr > new_end) {
1859 HeapWord* curr_end = curr;
1860 curr -= HeapRegion::GrainWords;
1861 _hr_printer.uncommit(curr, curr_end);
1862 }
1863 }
1864
1865 _expansion_regions += num_regions_removed;
1866 update_committed_space(old_end, new_end);
1867 HeapRegionRemSet::shrink_heap(n_regions());
1868 g1_policy()->record_new_heap_size(n_regions());
1869 } else {
1870 ergo_verbose0(ErgoHeapSizing,
1871 "did not shrink the heap",
1872 ergo_format_reason("heap shrinking operation failed"));
1873 }
1874 }
1875
1876 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1877 verify_region_sets_optional();
1878
1879 // We should only reach here at the end of a Full GC which means we
1880 // should not not be holding to any GC alloc regions. The method
1881 // below will make sure of that and do any remaining clean up.
1882 abandon_gc_alloc_regions();
1883
1884 // Instead of tearing down / rebuilding the free lists here, we
1885 // could instead use the remove_all_pending() method on free_list to
1886 // remove only the ones that we need to remove.
1887 tear_down_region_sets(true /* free_list_only */);
1888 shrink_helper(shrink_bytes);
1889 rebuild_region_sets(true /* free_list_only */);
1890
1891 _hrs.verify_optional();
1892 verify_region_sets_optional();
1893 }
1894
1895 // Public methods.
1896
1897 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1898 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1899 #endif // _MSC_VER
1900
1901
1902 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1903 SharedHeap(policy_),
1904 _g1_policy(policy_),
1905 _dirty_card_queue_set(false),
1906 _into_cset_dirty_card_queue_set(false),
1907 _is_alive_closure_cm(this),
1908 _is_alive_closure_stw(this),
1909 _ref_processor_cm(NULL),
1910 _ref_processor_stw(NULL),
1911 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1912 _bot_shared(NULL),
1913 _evac_failure_scan_stack(NULL),
1914 _mark_in_progress(false),
1915 _cg1r(NULL), _summary_bytes_used(0),
1916 _g1mm(NULL),
1917 _refine_cte_cl(NULL),
1918 _full_collection(false),
1919 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1920 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1921 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1922 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1923 _free_regions_coming(false),
1924 _young_list(new YoungList(this)),
1925 _gc_time_stamp(0),
1926 _retained_old_gc_alloc_region(NULL),
1927 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1928 _old_plab_stats(OldPLABSize, PLABWeight),
1929 _expand_heap_after_alloc_failure(true),
1930 _surviving_young_words(NULL),
1931 _old_marking_cycles_started(0),
1932 _old_marking_cycles_completed(0),
1933 _concurrent_cycle_started(false),
1934 _in_cset_fast_test(),
1935 _dirty_cards_region_list(NULL),
1936 _worker_cset_start_region(NULL),
1937 _worker_cset_start_region_time_stamp(NULL),
1938 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1939 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1940 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1941 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1942
1943 _g1h = this;
1944 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1945 vm_exit_during_initialization("Failed necessary allocation.");
1946 }
1947
1948 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1949
1950 int n_queues = MAX2((int)ParallelGCThreads, 1);
1951 _task_queues = new RefToScanQueueSet(n_queues);
1952
1953 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1954 assert(n_rem_sets > 0, "Invariant.");
1955
1956 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1957 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1958 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1959
1960 for (int i = 0; i < n_queues; i++) {
1961 RefToScanQueue* q = new RefToScanQueue();
1962 q->initialize();
1963 _task_queues->register_queue(i, q);
1964 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
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 size_t heap_alignment = collector_policy()->heap_alignment();
1998
1999 // Ensure that the sizes are properly aligned.
2000 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2001 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2002 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2003
2004 _cg1r = new ConcurrentG1Refine(this);
2005
2006 // Reserve the maximum.
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 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2020 heap_alignment);
2021
2022 // It is important to do this in a way such that concurrent readers can't
2023 // temporarily think something is in the heap. (I've actually seen this
2024 // happen in asserts: DLD.)
2025 _reserved.set_word_size(0);
2026 _reserved.set_start((HeapWord*)heap_rs.base());
2027 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2028
2029 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2030
2031 // Create the gen rem set (and barrier set) for the entire reserved region.
2032 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2033 set_barrier_set(rem_set()->bs());
2034 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2035 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2036 return JNI_ENOMEM;
2037 }
2038
2039 // Also create a G1 rem set.
2040 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2041
2042 // Carve out the G1 part of the heap.
2043
2044 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2045 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2046 g1_rs.size()/HeapWordSize);
2047
2048 _g1_storage.initialize(g1_rs, 0);
2049 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2050 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2051 (HeapWord*) _g1_reserved.end());
2052 assert(_hrs.max_length() == _expansion_regions,
2053 err_msg("max length: %u expansion regions: %u",
2054 _hrs.max_length(), _expansion_regions));
2055
2056 // Do later initialization work for concurrent refinement.
2057 _cg1r->init();
2058
2059 // 6843694 - ensure that the maximum region index can fit
2060 // in the remembered set structures.
2061 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2062 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2063
2064 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2065 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2066 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2067 "too many cards per region");
2068
2069 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2070
2071 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2072 heap_word_size(init_byte_size));
2073
2074 _g1h = this;
2075
2076 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2077
2078 // Create the ConcurrentMark data structure and thread.
2079 // (Must do this late, so that "max_regions" is defined.)
2080 _cm = new ConcurrentMark(this, heap_rs);
2081 if (_cm == NULL || !_cm->completed_initialization()) {
2082 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2083 return JNI_ENOMEM;
2084 }
2085 _cmThread = _cm->cmThread();
2086
2087 // Initialize the from_card cache structure of HeapRegionRemSet.
2088 HeapRegionRemSet::init_heap(max_regions());
2089
2090 // Now expand into the initial heap size.
2091 if (!expand(init_byte_size)) {
2092 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2093 return JNI_ENOMEM;
2094 }
2095
2096 // Perform any initialization actions delegated to the policy.
2097 g1_policy()->init();
2098
2099 _refine_cte_cl =
2100 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2101 g1_rem_set(),
2102 concurrent_g1_refine());
2103 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2104
2105 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2106 SATB_Q_FL_lock,
2107 G1SATBProcessCompletedThreshold,
2108 Shared_SATB_Q_lock);
2109
2110 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2111 DirtyCardQ_FL_lock,
2112 concurrent_g1_refine()->yellow_zone(),
2113 concurrent_g1_refine()->red_zone(),
2114 Shared_DirtyCardQ_lock);
2115
2116 if (G1DeferredRSUpdate) {
2117 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2118 DirtyCardQ_FL_lock,
2119 -1, // never trigger processing
2120 -1, // no limit on length
2121 Shared_DirtyCardQ_lock,
2122 &JavaThread::dirty_card_queue_set());
2123 }
2124
2125 // Initialize the card queue set used to hold cards containing
2126 // references into the collection set.
2127 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2128 DirtyCardQ_FL_lock,
2129 -1, // never trigger processing
2130 -1, // no limit on length
2131 Shared_DirtyCardQ_lock,
2132 &JavaThread::dirty_card_queue_set());
2133
2134 // In case we're keeping closure specialization stats, initialize those
2135 // counts and that mechanism.
2136 SpecializationStats::clear();
2137
2138 // Here we allocate the dummy full region that is required by the
2139 // G1AllocRegion class. If we don't pass an address in the reserved
2140 // space here, lots of asserts fire.
2141
2142 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2143 _g1_reserved.start());
2144 // We'll re-use the same region whether the alloc region will
2145 // require BOT updates or not and, if it doesn't, then a non-young
2146 // region will complain that it cannot support allocations without
2147 // BOT updates. So we'll tag the dummy region as young to avoid that.
2148 dummy_region->set_young();
2149 // Make sure it's full.
2150 dummy_region->set_top(dummy_region->end());
2151 G1AllocRegion::setup(this, dummy_region);
2152
2153 init_mutator_alloc_region();
2154
2155 // Do create of the monitoring and management support so that
2156 // values in the heap have been properly initialized.
2157 _g1mm = new G1MonitoringSupport(this);
2158
2159 G1StringDedup::initialize();
2160
2161 return JNI_OK;
2162 }
2163
2164 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2165 return HeapRegion::max_region_size();
2166 }
2167
2168 void G1CollectedHeap::ref_processing_init() {
2169 // Reference processing in G1 currently works as follows:
2170 //
2171 // * There are two reference processor instances. One is
2172 // used to record and process discovered references
2173 // during concurrent marking; the other is used to
2174 // record and process references during STW pauses
2175 // (both full and incremental).
2176 // * Both ref processors need to 'span' the entire heap as
2177 // the regions in the collection set may be dotted around.
2178 //
2179 // * For the concurrent marking ref processor:
2180 // * Reference discovery is enabled at initial marking.
2181 // * Reference discovery is disabled and the discovered
2182 // references processed etc during remarking.
2183 // * Reference discovery is MT (see below).
2184 // * Reference discovery requires a barrier (see below).
2185 // * Reference processing may or may not be MT
2186 // (depending on the value of ParallelRefProcEnabled
2187 // and ParallelGCThreads).
2188 // * A full GC disables reference discovery by the CM
2189 // ref processor and abandons any entries on it's
2190 // discovered lists.
2191 //
2192 // * For the STW processor:
2193 // * Non MT discovery is enabled at the start of a full GC.
2194 // * Processing and enqueueing during a full GC is non-MT.
2195 // * During a full GC, references are processed after marking.
2196 //
2197 // * Discovery (may or may not be MT) is enabled at the start
2198 // of an incremental evacuation pause.
2199 // * References are processed near the end of a STW evacuation pause.
2200 // * For both types of GC:
2201 // * Discovery is atomic - i.e. not concurrent.
2202 // * Reference discovery will not need a barrier.
2203
2204 SharedHeap::ref_processing_init();
2205 MemRegion mr = reserved_region();
2206
2207 // Concurrent Mark ref processor
2208 _ref_processor_cm =
2209 new ReferenceProcessor(mr, // span
2210 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2211 // mt processing
2212 (int) ParallelGCThreads,
2213 // degree of mt processing
2214 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2215 // mt discovery
2216 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2217 // degree of mt discovery
2218 false,
2219 // Reference discovery is not atomic
2220 &_is_alive_closure_cm,
2221 // is alive closure
2222 // (for efficiency/performance)
2223 true);
2224 // Setting next fields of discovered
2225 // lists requires a barrier.
2226
2227 // STW ref processor
2228 _ref_processor_stw =
2229 new ReferenceProcessor(mr, // span
2230 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2231 // mt processing
2232 MAX2((int)ParallelGCThreads, 1),
2233 // degree of mt processing
2234 (ParallelGCThreads > 1),
2235 // mt discovery
2236 MAX2((int)ParallelGCThreads, 1),
2237 // degree of mt discovery
2238 true,
2239 // Reference discovery is atomic
2240 &_is_alive_closure_stw,
2241 // is alive closure
2242 // (for efficiency/performance)
2243 false);
2244 // Setting next fields of discovered
2245 // lists does not require a barrier.
2246 }
2247
2248 size_t G1CollectedHeap::capacity() const {
2249 return _g1_committed.byte_size();
2250 }
2251
2252 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2253 assert(!hr->continuesHumongous(), "pre-condition");
2254 hr->reset_gc_time_stamp();
2255 if (hr->startsHumongous()) {
2256 uint first_index = hr->hrs_index() + 1;
2257 uint last_index = hr->last_hc_index();
2258 for (uint i = first_index; i < last_index; i += 1) {
2259 HeapRegion* chr = region_at(i);
2260 assert(chr->continuesHumongous(), "sanity");
2261 chr->reset_gc_time_stamp();
2262 }
2263 }
2264 }
2265
2266 #ifndef PRODUCT
2267 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2268 private:
2269 unsigned _gc_time_stamp;
2270 bool _failures;
2271
2272 public:
2273 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2274 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2275
2276 virtual bool doHeapRegion(HeapRegion* hr) {
2277 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2278 if (_gc_time_stamp != region_gc_time_stamp) {
2279 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2280 "expected %d", HR_FORMAT_PARAMS(hr),
2281 region_gc_time_stamp, _gc_time_stamp);
2282 _failures = true;
2283 }
2284 return false;
2285 }
2286
2287 bool failures() { return _failures; }
2288 };
2289
2290 void G1CollectedHeap::check_gc_time_stamps() {
2291 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2292 heap_region_iterate(&cl);
2293 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2294 }
2295 #endif // PRODUCT
2296
2297 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2298 DirtyCardQueue* into_cset_dcq,
2299 bool concurrent,
2300 uint worker_i) {
2301 // Clean cards in the hot card cache
2302 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2303 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2304
2305 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2306 int n_completed_buffers = 0;
2307 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2308 n_completed_buffers++;
2309 }
2310 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2311 dcqs.clear_n_completed_buffers();
2312 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2313 }
2314
2315
2316 // Computes the sum of the storage used by the various regions.
2317
2318 size_t G1CollectedHeap::used() const {
2319 assert(Heap_lock->owner() != NULL,
2320 "Should be owned on this thread's behalf.");
2321 size_t result = _summary_bytes_used;
2322 // Read only once in case it is set to NULL concurrently
2323 HeapRegion* hr = _mutator_alloc_region.get();
2324 if (hr != NULL)
2325 result += hr->used();
2326 return result;
2327 }
2328
2329 size_t G1CollectedHeap::used_unlocked() const {
2330 size_t result = _summary_bytes_used;
2331 return result;
2332 }
2333
2334 class SumUsedClosure: public HeapRegionClosure {
2335 size_t _used;
2336 public:
2337 SumUsedClosure() : _used(0) {}
2338 bool doHeapRegion(HeapRegion* r) {
2339 if (!r->continuesHumongous()) {
2340 _used += r->used();
2341 }
2342 return false;
2343 }
2344 size_t result() { return _used; }
2345 };
2346
2347 size_t G1CollectedHeap::recalculate_used() const {
2348 double recalculate_used_start = os::elapsedTime();
2349
2350 SumUsedClosure blk;
2351 heap_region_iterate(&blk);
2352
2353 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2354 return blk.result();
2355 }
2356
2357 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2358 switch (cause) {
2359 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2360 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2361 case GCCause::_g1_humongous_allocation: return true;
2362 default: return false;
2363 }
2364 }
2365
2366 #ifndef PRODUCT
2367 void G1CollectedHeap::allocate_dummy_regions() {
2368 // Let's fill up most of the region
2369 size_t word_size = HeapRegion::GrainWords - 1024;
2370 // And as a result the region we'll allocate will be humongous.
2371 guarantee(isHumongous(word_size), "sanity");
2372
2373 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2374 // Let's use the existing mechanism for the allocation
2375 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2376 if (dummy_obj != NULL) {
2377 MemRegion mr(dummy_obj, word_size);
2378 CollectedHeap::fill_with_object(mr);
2379 } else {
2380 // If we can't allocate once, we probably cannot allocate
2381 // again. Let's get out of the loop.
2382 break;
2383 }
2384 }
2385 }
2386 #endif // !PRODUCT
2387
2388 void G1CollectedHeap::increment_old_marking_cycles_started() {
2389 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2390 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2391 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2392 _old_marking_cycles_started, _old_marking_cycles_completed));
2393
2394 _old_marking_cycles_started++;
2395 }
2396
2397 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2398 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2399
2400 // We assume that if concurrent == true, then the caller is a
2401 // concurrent thread that was joined the Suspendible Thread
2402 // Set. If there's ever a cheap way to check this, we should add an
2403 // assert here.
2404
2405 // Given that this method is called at the end of a Full GC or of a
2406 // concurrent cycle, and those can be nested (i.e., a Full GC can
2407 // interrupt a concurrent cycle), the number of full collections
2408 // completed should be either one (in the case where there was no
2409 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2410 // behind the number of full collections started.
2411
2412 // This is the case for the inner caller, i.e. a Full GC.
2413 assert(concurrent ||
2414 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2415 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2416 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2417 "is inconsistent with _old_marking_cycles_completed = %u",
2418 _old_marking_cycles_started, _old_marking_cycles_completed));
2419
2420 // This is the case for the outer caller, i.e. the concurrent cycle.
2421 assert(!concurrent ||
2422 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2423 err_msg("for outer caller (concurrent cycle): "
2424 "_old_marking_cycles_started = %u "
2425 "is inconsistent with _old_marking_cycles_completed = %u",
2426 _old_marking_cycles_started, _old_marking_cycles_completed));
2427
2428 _old_marking_cycles_completed += 1;
2429
2430 // We need to clear the "in_progress" flag in the CM thread before
2431 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2432 // is set) so that if a waiter requests another System.gc() it doesn't
2433 // incorrectly see that a marking cycle is still in progress.
2434 if (concurrent) {
2435 _cmThread->clear_in_progress();
2436 }
2437
2438 // This notify_all() will ensure that a thread that called
2439 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2440 // and it's waiting for a full GC to finish will be woken up. It is
2441 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2442 FullGCCount_lock->notify_all();
2443 }
2444
2445 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2446 _concurrent_cycle_started = true;
2447 _gc_timer_cm->register_gc_start(start_time);
2448
2449 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2450 trace_heap_before_gc(_gc_tracer_cm);
2451 }
2452
2453 void G1CollectedHeap::register_concurrent_cycle_end() {
2454 if (_concurrent_cycle_started) {
2455 if (_cm->has_aborted()) {
2456 _gc_tracer_cm->report_concurrent_mode_failure();
2457 }
2458
2459 _gc_timer_cm->register_gc_end();
2460 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2461
2462 _concurrent_cycle_started = false;
2463 }
2464 }
2465
2466 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2467 if (_concurrent_cycle_started) {
2468 trace_heap_after_gc(_gc_tracer_cm);
2469 }
2470 }
2471
2472 G1YCType G1CollectedHeap::yc_type() {
2473 bool is_young = g1_policy()->gcs_are_young();
2474 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2475 bool is_during_mark = mark_in_progress();
2476
2477 if (is_initial_mark) {
2478 return InitialMark;
2479 } else if (is_during_mark) {
2480 return DuringMark;
2481 } else if (is_young) {
2482 return Normal;
2483 } else {
2484 return Mixed;
2485 }
2486 }
2487
2488 void G1CollectedHeap::collect(GCCause::Cause cause) {
2489 assert_heap_not_locked();
2490
2491 unsigned int gc_count_before;
2492 unsigned int old_marking_count_before;
2493 bool retry_gc;
2494
2495 do {
2496 retry_gc = false;
2497
2498 {
2499 MutexLocker ml(Heap_lock);
2500
2501 // Read the GC count while holding the Heap_lock
2502 gc_count_before = total_collections();
2503 old_marking_count_before = _old_marking_cycles_started;
2504 }
2505
2506 if (should_do_concurrent_full_gc(cause)) {
2507 // Schedule an initial-mark evacuation pause that will start a
2508 // concurrent cycle. We're setting word_size to 0 which means that
2509 // we are not requesting a post-GC allocation.
2510 VM_G1IncCollectionPause op(gc_count_before,
2511 0, /* word_size */
2512 true, /* should_initiate_conc_mark */
2513 g1_policy()->max_pause_time_ms(),
2514 cause);
2515
2516 VMThread::execute(&op);
2517 if (!op.pause_succeeded()) {
2518 if (old_marking_count_before == _old_marking_cycles_started) {
2519 retry_gc = op.should_retry_gc();
2520 } else {
2521 // A Full GC happened while we were trying to schedule the
2522 // initial-mark GC. No point in starting a new cycle given
2523 // that the whole heap was collected anyway.
2524 }
2525
2526 if (retry_gc) {
2527 if (GC_locker::is_active_and_needs_gc()) {
2528 GC_locker::stall_until_clear();
2529 }
2530 }
2531 }
2532 } else {
2533 if (cause == GCCause::_gc_locker
2534 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2535
2536 // Schedule a standard evacuation pause. We're setting word_size
2537 // to 0 which means that we are not requesting a post-GC allocation.
2538 VM_G1IncCollectionPause op(gc_count_before,
2539 0, /* word_size */
2540 false, /* should_initiate_conc_mark */
2541 g1_policy()->max_pause_time_ms(),
2542 cause);
2543 VMThread::execute(&op);
2544 } else {
2545 // Schedule a Full GC.
2546 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2547 VMThread::execute(&op);
2548 }
2549 }
2550 } while (retry_gc);
2551 }
2552
2553 bool G1CollectedHeap::is_in(const void* p) const {
2554 if (_g1_committed.contains(p)) {
2555 // Given that we know that p is in the committed space,
2556 // heap_region_containing_raw() should successfully
2557 // return the containing region.
2558 HeapRegion* hr = heap_region_containing_raw(p);
2559 return hr->is_in(p);
2560 } else {
2561 return false;
2562 }
2563 }
2564
2565 // Iteration functions.
2566
2567 // Iterates an OopClosure over all ref-containing fields of objects
2568 // within a HeapRegion.
2569
2570 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2571 MemRegion _mr;
2572 ExtendedOopClosure* _cl;
2573 public:
2574 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2575 : _mr(mr), _cl(cl) {}
2576 bool doHeapRegion(HeapRegion* r) {
2577 if (!r->continuesHumongous()) {
2578 r->oop_iterate(_cl);
2579 }
2580 return false;
2581 }
2582 };
2583
2584 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2585 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2586 heap_region_iterate(&blk);
2587 }
2588
2589 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2590 IterateOopClosureRegionClosure blk(mr, cl);
2591 heap_region_iterate(&blk);
2592 }
2593
2594 // Iterates an ObjectClosure over all objects within a HeapRegion.
2595
2596 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2597 ObjectClosure* _cl;
2598 public:
2599 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2600 bool doHeapRegion(HeapRegion* r) {
2601 if (! r->continuesHumongous()) {
2602 r->object_iterate(_cl);
2603 }
2604 return false;
2605 }
2606 };
2607
2608 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2609 IterateObjectClosureRegionClosure blk(cl);
2610 heap_region_iterate(&blk);
2611 }
2612
2613 // Calls a SpaceClosure on a HeapRegion.
2614
2615 class SpaceClosureRegionClosure: public HeapRegionClosure {
2616 SpaceClosure* _cl;
2617 public:
2618 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2619 bool doHeapRegion(HeapRegion* r) {
2620 _cl->do_space(r);
2621 return false;
2622 }
2623 };
2624
2625 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2626 SpaceClosureRegionClosure blk(cl);
2627 heap_region_iterate(&blk);
2628 }
2629
2630 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2631 _hrs.iterate(cl);
2632 }
2633
2634 void
2635 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2636 uint worker_id,
2637 uint no_of_par_workers,
2638 jint claim_value) {
2639 const uint regions = n_regions();
2640 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2641 no_of_par_workers :
2642 1);
2643 assert(UseDynamicNumberOfGCThreads ||
2644 no_of_par_workers == workers()->total_workers(),
2645 "Non dynamic should use fixed number of workers");
2646 // try to spread out the starting points of the workers
2647 const HeapRegion* start_hr =
2648 start_region_for_worker(worker_id, no_of_par_workers);
2649 const uint start_index = start_hr->hrs_index();
2650
2651 // each worker will actually look at all regions
2652 for (uint count = 0; count < regions; ++count) {
2653 const uint index = (start_index + count) % regions;
2654 assert(0 <= index && index < regions, "sanity");
2655 HeapRegion* r = region_at(index);
2656 // we'll ignore "continues humongous" regions (we'll process them
2657 // when we come across their corresponding "start humongous"
2658 // region) and regions already claimed
2659 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2660 continue;
2661 }
2662 // OK, try to claim it
2663 if (r->claimHeapRegion(claim_value)) {
2664 // success!
2665 assert(!r->continuesHumongous(), "sanity");
2666 if (r->startsHumongous()) {
2667 // If the region is "starts humongous" we'll iterate over its
2668 // "continues humongous" first; in fact we'll do them
2669 // first. The order is important. In on case, calling the
2670 // closure on the "starts humongous" region might de-allocate
2671 // and clear all its "continues humongous" regions and, as a
2672 // result, we might end up processing them twice. So, we'll do
2673 // them first (notice: most closures will ignore them anyway) and
2674 // then we'll do the "starts humongous" region.
2675 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2676 HeapRegion* chr = region_at(ch_index);
2677
2678 // if the region has already been claimed or it's not
2679 // "continues humongous" we're done
2680 if (chr->claim_value() == claim_value ||
2681 !chr->continuesHumongous()) {
2682 break;
2683 }
2684
2685 // No one should have claimed it directly. We can given
2686 // that we claimed its "starts humongous" region.
2687 assert(chr->claim_value() != claim_value, "sanity");
2688 assert(chr->humongous_start_region() == r, "sanity");
2689
2690 if (chr->claimHeapRegion(claim_value)) {
2691 // we should always be able to claim it; no one else should
2692 // be trying to claim this region
2693
2694 bool res2 = cl->doHeapRegion(chr);
2695 assert(!res2, "Should not abort");
2696
2697 // Right now, this holds (i.e., no closure that actually
2698 // does something with "continues humongous" regions
2699 // clears them). We might have to weaken it in the future,
2700 // but let's leave these two asserts here for extra safety.
2701 assert(chr->continuesHumongous(), "should still be the case");
2702 assert(chr->humongous_start_region() == r, "sanity");
2703 } else {
2704 guarantee(false, "we should not reach here");
2705 }
2706 }
2707 }
2708
2709 assert(!r->continuesHumongous(), "sanity");
2710 bool res = cl->doHeapRegion(r);
2711 assert(!res, "Should not abort");
2712 }
2713 }
2714 }
2715
2716 class ResetClaimValuesClosure: public HeapRegionClosure {
2717 public:
2718 bool doHeapRegion(HeapRegion* r) {
2719 r->set_claim_value(HeapRegion::InitialClaimValue);
2720 return false;
2721 }
2722 };
2723
2724 void G1CollectedHeap::reset_heap_region_claim_values() {
2725 ResetClaimValuesClosure blk;
2726 heap_region_iterate(&blk);
2727 }
2728
2729 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2730 ResetClaimValuesClosure blk;
2731 collection_set_iterate(&blk);
2732 }
2733
2734 #ifdef ASSERT
2735 // This checks whether all regions in the heap have the correct claim
2736 // value. I also piggy-backed on this a check to ensure that the
2737 // humongous_start_region() information on "continues humongous"
2738 // regions is correct.
2739
2740 class CheckClaimValuesClosure : public HeapRegionClosure {
2741 private:
2742 jint _claim_value;
2743 uint _failures;
2744 HeapRegion* _sh_region;
2745
2746 public:
2747 CheckClaimValuesClosure(jint claim_value) :
2748 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2749 bool doHeapRegion(HeapRegion* r) {
2750 if (r->claim_value() != _claim_value) {
2751 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2752 "claim value = %d, should be %d",
2753 HR_FORMAT_PARAMS(r),
2754 r->claim_value(), _claim_value);
2755 ++_failures;
2756 }
2757 if (!r->isHumongous()) {
2758 _sh_region = NULL;
2759 } else if (r->startsHumongous()) {
2760 _sh_region = r;
2761 } else if (r->continuesHumongous()) {
2762 if (r->humongous_start_region() != _sh_region) {
2763 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2764 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2765 HR_FORMAT_PARAMS(r),
2766 r->humongous_start_region(),
2767 _sh_region);
2768 ++_failures;
2769 }
2770 }
2771 return false;
2772 }
2773 uint failures() { return _failures; }
2774 };
2775
2776 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2777 CheckClaimValuesClosure cl(claim_value);
2778 heap_region_iterate(&cl);
2779 return cl.failures() == 0;
2780 }
2781
2782 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2783 private:
2784 jint _claim_value;
2785 uint _failures;
2786
2787 public:
2788 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2789 _claim_value(claim_value), _failures(0) { }
2790
2791 uint failures() { return _failures; }
2792
2793 bool doHeapRegion(HeapRegion* hr) {
2794 assert(hr->in_collection_set(), "how?");
2795 assert(!hr->isHumongous(), "H-region in CSet");
2796 if (hr->claim_value() != _claim_value) {
2797 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2798 "claim value = %d, should be %d",
2799 HR_FORMAT_PARAMS(hr),
2800 hr->claim_value(), _claim_value);
2801 _failures += 1;
2802 }
2803 return false;
2804 }
2805 };
2806
2807 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2808 CheckClaimValuesInCSetHRClosure cl(claim_value);
2809 collection_set_iterate(&cl);
2810 return cl.failures() == 0;
2811 }
2812 #endif // ASSERT
2813
2814 // Clear the cached CSet starting regions and (more importantly)
2815 // the time stamps. Called when we reset the GC time stamp.
2816 void G1CollectedHeap::clear_cset_start_regions() {
2817 assert(_worker_cset_start_region != NULL, "sanity");
2818 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2819
2820 int n_queues = MAX2((int)ParallelGCThreads, 1);
2821 for (int i = 0; i < n_queues; i++) {
2822 _worker_cset_start_region[i] = NULL;
2823 _worker_cset_start_region_time_stamp[i] = 0;
2824 }
2825 }
2826
2827 // Given the id of a worker, obtain or calculate a suitable
2828 // starting region for iterating over the current collection set.
2829 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2830 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2831
2832 HeapRegion* result = NULL;
2833 unsigned gc_time_stamp = get_gc_time_stamp();
2834
2835 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2836 // Cached starting region for current worker was set
2837 // during the current pause - so it's valid.
2838 // Note: the cached starting heap region may be NULL
2839 // (when the collection set is empty).
2840 result = _worker_cset_start_region[worker_i];
2841 assert(result == NULL || result->in_collection_set(), "sanity");
2842 return result;
2843 }
2844
2845 // The cached entry was not valid so let's calculate
2846 // a suitable starting heap region for this worker.
2847
2848 // We want the parallel threads to start their collection
2849 // set iteration at different collection set regions to
2850 // avoid contention.
2851 // If we have:
2852 // n collection set regions
2853 // p threads
2854 // Then thread t will start at region floor ((t * n) / p)
2855
2856 result = g1_policy()->collection_set();
2857 if (G1CollectedHeap::use_parallel_gc_threads()) {
2858 uint cs_size = g1_policy()->cset_region_length();
2859 uint active_workers = workers()->active_workers();
2860 assert(UseDynamicNumberOfGCThreads ||
2861 active_workers == workers()->total_workers(),
2862 "Unless dynamic should use total workers");
2863
2864 uint end_ind = (cs_size * worker_i) / active_workers;
2865 uint start_ind = 0;
2866
2867 if (worker_i > 0 &&
2868 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2869 // Previous workers starting region is valid
2870 // so let's iterate from there
2871 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2872 result = _worker_cset_start_region[worker_i - 1];
2873 }
2874
2875 for (uint i = start_ind; i < end_ind; i++) {
2876 result = result->next_in_collection_set();
2877 }
2878 }
2879
2880 // Note: the calculated starting heap region may be NULL
2881 // (when the collection set is empty).
2882 assert(result == NULL || result->in_collection_set(), "sanity");
2883 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2884 "should be updated only once per pause");
2885 _worker_cset_start_region[worker_i] = result;
2886 OrderAccess::storestore();
2887 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2888 return result;
2889 }
2890
2891 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2892 uint no_of_par_workers) {
2893 uint worker_num =
2894 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2895 assert(UseDynamicNumberOfGCThreads ||
2896 no_of_par_workers == workers()->total_workers(),
2897 "Non dynamic should use fixed number of workers");
2898 const uint start_index = n_regions() * worker_i / worker_num;
2899 return region_at(start_index);
2900 }
2901
2902 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2903 HeapRegion* r = g1_policy()->collection_set();
2904 while (r != NULL) {
2905 HeapRegion* next = r->next_in_collection_set();
2906 if (cl->doHeapRegion(r)) {
2907 cl->incomplete();
2908 return;
2909 }
2910 r = next;
2911 }
2912 }
2913
2914 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2915 HeapRegionClosure *cl) {
2916 if (r == NULL) {
2917 // The CSet is empty so there's nothing to do.
2918 return;
2919 }
2920
2921 assert(r->in_collection_set(),
2922 "Start region must be a member of the collection set.");
2923 HeapRegion* cur = r;
2924 while (cur != NULL) {
2925 HeapRegion* next = cur->next_in_collection_set();
2926 if (cl->doHeapRegion(cur) && false) {
2927 cl->incomplete();
2928 return;
2929 }
2930 cur = next;
2931 }
2932 cur = g1_policy()->collection_set();
2933 while (cur != r) {
2934 HeapRegion* next = cur->next_in_collection_set();
2935 if (cl->doHeapRegion(cur) && false) {
2936 cl->incomplete();
2937 return;
2938 }
2939 cur = next;
2940 }
2941 }
2942
2943 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2944 return n_regions() > 0 ? region_at(0) : NULL;
2945 }
2946
2947
2948 Space* G1CollectedHeap::space_containing(const void* addr) const {
2949 Space* res = heap_region_containing(addr);
2950 return res;
2951 }
2952
2953 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2954 Space* sp = space_containing(addr);
2955 if (sp != NULL) {
2956 return sp->block_start(addr);
2957 }
2958 return NULL;
2959 }
2960
2961 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2962 Space* sp = space_containing(addr);
2963 assert(sp != NULL, "block_size of address outside of heap");
2964 return sp->block_size(addr);
2965 }
2966
2967 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2968 Space* sp = space_containing(addr);
2969 return sp->block_is_obj(addr);
2970 }
2971
2972 bool G1CollectedHeap::supports_tlab_allocation() const {
2973 return true;
2974 }
2975
2976 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2977 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2978 }
2979
2980 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2981 return young_list()->eden_used_bytes();
2982 }
2983
2984 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2985 // must be smaller than the humongous object limit.
2986 size_t G1CollectedHeap::max_tlab_size() const {
2987 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2988 }
2989
2990 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2991 // Return the remaining space in the cur alloc region, but not less than
2992 // the min TLAB size.
2993
2994 // Also, this value can be at most the humongous object threshold,
2995 // since we can't allow tlabs to grow big enough to accommodate
2996 // humongous objects.
2997
2998 HeapRegion* hr = _mutator_alloc_region.get();
2999 size_t max_tlab = max_tlab_size() * wordSize;
3000 if (hr == NULL) {
3001 return max_tlab;
3002 } else {
3003 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3004 }
3005 }
3006
3007 size_t G1CollectedHeap::max_capacity() const {
3008 return _g1_reserved.byte_size();
3009 }
3010
3011 jlong G1CollectedHeap::millis_since_last_gc() {
3012 // assert(false, "NYI");
3013 return 0;
3014 }
3015
3016 void G1CollectedHeap::prepare_for_verify() {
3017 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3018 ensure_parsability(false);
3019 }
3020 g1_rem_set()->prepare_for_verify();
3021 }
3022
3023 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3024 VerifyOption vo) {
3025 switch (vo) {
3026 case VerifyOption_G1UsePrevMarking:
3027 return hr->obj_allocated_since_prev_marking(obj);
3028 case VerifyOption_G1UseNextMarking:
3029 return hr->obj_allocated_since_next_marking(obj);
3030 case VerifyOption_G1UseMarkWord:
3031 return false;
3032 default:
3033 ShouldNotReachHere();
3034 }
3035 return false; // keep some compilers happy
3036 }
3037
3038 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3039 switch (vo) {
3040 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3041 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3042 case VerifyOption_G1UseMarkWord: return NULL;
3043 default: ShouldNotReachHere();
3044 }
3045 return NULL; // keep some compilers happy
3046 }
3047
3048 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3049 switch (vo) {
3050 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3051 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3052 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3053 default: ShouldNotReachHere();
3054 }
3055 return false; // keep some compilers happy
3056 }
3057
3058 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3059 switch (vo) {
3060 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3061 case VerifyOption_G1UseNextMarking: return "NTAMS";
3062 case VerifyOption_G1UseMarkWord: return "NONE";
3063 default: ShouldNotReachHere();
3064 }
3065 return NULL; // keep some compilers happy
3066 }
3067
3068 class VerifyRootsClosure: public OopClosure {
3069 private:
3070 G1CollectedHeap* _g1h;
3071 VerifyOption _vo;
3072 bool _failures;
3073 public:
3074 // _vo == UsePrevMarking -> use "prev" marking information,
3075 // _vo == UseNextMarking -> use "next" marking information,
3076 // _vo == UseMarkWord -> use mark word from object header.
3077 VerifyRootsClosure(VerifyOption vo) :
3078 _g1h(G1CollectedHeap::heap()),
3079 _vo(vo),
3080 _failures(false) { }
3081
3082 bool failures() { return _failures; }
3083
3084 template <class T> void do_oop_nv(T* p) {
3085 T heap_oop = oopDesc::load_heap_oop(p);
3086 if (!oopDesc::is_null(heap_oop)) {
3087 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3088 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3089 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3090 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3091 if (_vo == VerifyOption_G1UseMarkWord) {
3092 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3093 }
3094 obj->print_on(gclog_or_tty);
3095 _failures = true;
3096 }
3097 }
3098 }
3099
3100 void do_oop(oop* p) { do_oop_nv(p); }
3101 void do_oop(narrowOop* p) { do_oop_nv(p); }
3102 };
3103
3104 class G1VerifyCodeRootOopClosure: public OopClosure {
3105 G1CollectedHeap* _g1h;
3106 OopClosure* _root_cl;
3107 nmethod* _nm;
3108 VerifyOption _vo;
3109 bool _failures;
3110
3111 template <class T> void do_oop_work(T* p) {
3112 // First verify that this root is live
3113 _root_cl->do_oop(p);
3114
3115 if (!G1VerifyHeapRegionCodeRoots) {
3116 // We're not verifying the code roots attached to heap region.
3117 return;
3118 }
3119
3120 // Don't check the code roots during marking verification in a full GC
3121 if (_vo == VerifyOption_G1UseMarkWord) {
3122 return;
3123 }
3124
3125 // Now verify that the current nmethod (which contains p) is
3126 // in the code root list of the heap region containing the
3127 // object referenced by p.
3128
3129 T heap_oop = oopDesc::load_heap_oop(p);
3130 if (!oopDesc::is_null(heap_oop)) {
3131 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3132
3133 // Now fetch the region containing the object
3134 HeapRegion* hr = _g1h->heap_region_containing(obj);
3135 HeapRegionRemSet* hrrs = hr->rem_set();
3136 // Verify that the strong code root list for this region
3137 // contains the nmethod
3138 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3139 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3140 "from nmethod "PTR_FORMAT" not in strong "
3141 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3142 p, _nm, hr->bottom(), hr->end());
3143 _failures = true;
3144 }
3145 }
3146 }
3147
3148 public:
3149 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3150 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3151
3152 void do_oop(oop* p) { do_oop_work(p); }
3153 void do_oop(narrowOop* p) { do_oop_work(p); }
3154
3155 void set_nmethod(nmethod* nm) { _nm = nm; }
3156 bool failures() { return _failures; }
3157 };
3158
3159 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3160 G1VerifyCodeRootOopClosure* _oop_cl;
3161
3162 public:
3163 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3164 _oop_cl(oop_cl) {}
3165
3166 void do_code_blob(CodeBlob* cb) {
3167 nmethod* nm = cb->as_nmethod_or_null();
3168 if (nm != NULL) {
3169 _oop_cl->set_nmethod(nm);
3170 nm->oops_do(_oop_cl);
3171 }
3172 }
3173 };
3174
3175 class YoungRefCounterClosure : public OopClosure {
3176 G1CollectedHeap* _g1h;
3177 int _count;
3178 public:
3179 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3180 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3181 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3182
3183 int count() { return _count; }
3184 void reset_count() { _count = 0; };
3185 };
3186
3187 class VerifyKlassClosure: public KlassClosure {
3188 YoungRefCounterClosure _young_ref_counter_closure;
3189 OopClosure *_oop_closure;
3190 public:
3191 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3192 void do_klass(Klass* k) {
3193 k->oops_do(_oop_closure);
3194
3195 _young_ref_counter_closure.reset_count();
3196 k->oops_do(&_young_ref_counter_closure);
3197 if (_young_ref_counter_closure.count() > 0) {
3198 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3199 }
3200 }
3201 };
3202
3203 class VerifyLivenessOopClosure: public OopClosure {
3204 G1CollectedHeap* _g1h;
3205 VerifyOption _vo;
3206 public:
3207 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3208 _g1h(g1h), _vo(vo)
3209 { }
3210 void do_oop(narrowOop *p) { do_oop_work(p); }
3211 void do_oop( oop *p) { do_oop_work(p); }
3212
3213 template <class T> void do_oop_work(T *p) {
3214 oop obj = oopDesc::load_decode_heap_oop(p);
3215 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3216 "Dead object referenced by a not dead object");
3217 }
3218 };
3219
3220 class VerifyObjsInRegionClosure: public ObjectClosure {
3221 private:
3222 G1CollectedHeap* _g1h;
3223 size_t _live_bytes;
3224 HeapRegion *_hr;
3225 VerifyOption _vo;
3226 public:
3227 // _vo == UsePrevMarking -> use "prev" marking information,
3228 // _vo == UseNextMarking -> use "next" marking information,
3229 // _vo == UseMarkWord -> use mark word from object header.
3230 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3231 : _live_bytes(0), _hr(hr), _vo(vo) {
3232 _g1h = G1CollectedHeap::heap();
3233 }
3234 void do_object(oop o) {
3235 VerifyLivenessOopClosure isLive(_g1h, _vo);
3236 assert(o != NULL, "Huh?");
3237 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3238 // If the object is alive according to the mark word,
3239 // then verify that the marking information agrees.
3240 // Note we can't verify the contra-positive of the
3241 // above: if the object is dead (according to the mark
3242 // word), it may not be marked, or may have been marked
3243 // but has since became dead, or may have been allocated
3244 // since the last marking.
3245 if (_vo == VerifyOption_G1UseMarkWord) {
3246 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3247 }
3248
3249 o->oop_iterate_no_header(&isLive);
3250 if (!_hr->obj_allocated_since_prev_marking(o)) {
3251 size_t obj_size = o->size(); // Make sure we don't overflow
3252 _live_bytes += (obj_size * HeapWordSize);
3253 }
3254 }
3255 }
3256 size_t live_bytes() { return _live_bytes; }
3257 };
3258
3259 class PrintObjsInRegionClosure : public ObjectClosure {
3260 HeapRegion *_hr;
3261 G1CollectedHeap *_g1;
3262 public:
3263 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3264 _g1 = G1CollectedHeap::heap();
3265 };
3266
3267 void do_object(oop o) {
3268 if (o != NULL) {
3269 HeapWord *start = (HeapWord *) o;
3270 size_t word_sz = o->size();
3271 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3272 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3273 (void*) o, word_sz,
3274 _g1->isMarkedPrev(o),
3275 _g1->isMarkedNext(o),
3276 _hr->obj_allocated_since_prev_marking(o));
3277 HeapWord *end = start + word_sz;
3278 HeapWord *cur;
3279 int *val;
3280 for (cur = start; cur < end; cur++) {
3281 val = (int *) cur;
3282 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3283 }
3284 }
3285 }
3286 };
3287
3288 class VerifyRegionClosure: public HeapRegionClosure {
3289 private:
3290 bool _par;
3291 VerifyOption _vo;
3292 bool _failures;
3293 public:
3294 // _vo == UsePrevMarking -> use "prev" marking information,
3295 // _vo == UseNextMarking -> use "next" marking information,
3296 // _vo == UseMarkWord -> use mark word from object header.
3297 VerifyRegionClosure(bool par, VerifyOption vo)
3298 : _par(par),
3299 _vo(vo),
3300 _failures(false) {}
3301
3302 bool failures() {
3303 return _failures;
3304 }
3305
3306 bool doHeapRegion(HeapRegion* r) {
3307 if (!r->continuesHumongous()) {
3308 bool failures = false;
3309 r->verify(_vo, &failures);
3310 if (failures) {
3311 _failures = true;
3312 } else {
3313 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3314 r->object_iterate(¬_dead_yet_cl);
3315 if (_vo != VerifyOption_G1UseNextMarking) {
3316 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3317 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3318 "max_live_bytes "SIZE_FORMAT" "
3319 "< calculated "SIZE_FORMAT,
3320 r->bottom(), r->end(),
3321 r->max_live_bytes(),
3322 not_dead_yet_cl.live_bytes());
3323 _failures = true;
3324 }
3325 } else {
3326 // When vo == UseNextMarking we cannot currently do a sanity
3327 // check on the live bytes as the calculation has not been
3328 // finalized yet.
3329 }
3330 }
3331 }
3332 return false; // stop the region iteration if we hit a failure
3333 }
3334 };
3335
3336 // This is the task used for parallel verification of the heap regions
3337
3338 class G1ParVerifyTask: public AbstractGangTask {
3339 private:
3340 G1CollectedHeap* _g1h;
3341 VerifyOption _vo;
3342 bool _failures;
3343
3344 public:
3345 // _vo == UsePrevMarking -> use "prev" marking information,
3346 // _vo == UseNextMarking -> use "next" marking information,
3347 // _vo == UseMarkWord -> use mark word from object header.
3348 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3349 AbstractGangTask("Parallel verify task"),
3350 _g1h(g1h),
3351 _vo(vo),
3352 _failures(false) { }
3353
3354 bool failures() {
3355 return _failures;
3356 }
3357
3358 void work(uint worker_id) {
3359 HandleMark hm;
3360 VerifyRegionClosure blk(true, _vo);
3361 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3362 _g1h->workers()->active_workers(),
3363 HeapRegion::ParVerifyClaimValue);
3364 if (blk.failures()) {
3365 _failures = true;
3366 }
3367 }
3368 };
3369
3370 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3371 if (SafepointSynchronize::is_at_safepoint()) {
3372 assert(Thread::current()->is_VM_thread(),
3373 "Expected to be executed serially by the VM thread at this point");
3374
3375 if (!silent) { gclog_or_tty->print("Roots "); }
3376 VerifyRootsClosure rootsCl(vo);
3377 VerifyKlassClosure klassCl(this, &rootsCl);
3378
3379 // We apply the relevant closures to all the oops in the
3380 // system dictionary, class loader data graph and the string table.
3381 // Don't verify the code cache here, since it's verified below.
3382 const int so = SO_AllClasses | SO_Strings;
3383
3384 // Need cleared claim bits for the strong roots processing
3385 ClassLoaderDataGraph::clear_claimed_marks();
3386
3387 process_strong_roots(true, // activate StrongRootsScope
3388 ScanningOption(so), // roots scanning options
3389 &rootsCl,
3390 &klassCl
3391 );
3392
3393 // Verify the nmethods in the code cache.
3394 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3395 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3396 CodeCache::blobs_do(&blobsCl);
3397
3398 bool failures = rootsCl.failures() || codeRootsCl.failures();
3399
3400 if (vo != VerifyOption_G1UseMarkWord) {
3401 // If we're verifying during a full GC then the region sets
3402 // will have been torn down at the start of the GC. Therefore
3403 // verifying the region sets will fail. So we only verify
3404 // the region sets when not in a full GC.
3405 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3406 verify_region_sets();
3407 }
3408
3409 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3410 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3411 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3412 "sanity check");
3413
3414 G1ParVerifyTask task(this, vo);
3415 assert(UseDynamicNumberOfGCThreads ||
3416 workers()->active_workers() == workers()->total_workers(),
3417 "If not dynamic should be using all the workers");
3418 int n_workers = workers()->active_workers();
3419 set_par_threads(n_workers);
3420 workers()->run_task(&task);
3421 set_par_threads(0);
3422 if (task.failures()) {
3423 failures = true;
3424 }
3425
3426 // Checks that the expected amount of parallel work was done.
3427 // The implication is that n_workers is > 0.
3428 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3429 "sanity check");
3430
3431 reset_heap_region_claim_values();
3432
3433 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3434 "sanity check");
3435 } else {
3436 VerifyRegionClosure blk(false, vo);
3437 heap_region_iterate(&blk);
3438 if (blk.failures()) {
3439 failures = true;
3440 }
3441 }
3442 if (!silent) gclog_or_tty->print("RemSet ");
3443 rem_set()->verify();
3444
3445 if (G1StringDedup::is_enabled()) {
3446 if (!silent) gclog_or_tty->print("StrDedup ");
3447 G1StringDedup::verify();
3448 }
3449
3450 if (failures) {
3451 gclog_or_tty->print_cr("Heap:");
3452 // It helps to have the per-region information in the output to
3453 // help us track down what went wrong. This is why we call
3454 // print_extended_on() instead of print_on().
3455 print_extended_on(gclog_or_tty);
3456 gclog_or_tty->print_cr("");
3457 #ifndef PRODUCT
3458 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3459 concurrent_mark()->print_reachable("at-verification-failure",
3460 vo, false /* all */);
3461 }
3462 #endif
3463 gclog_or_tty->flush();
3464 }
3465 guarantee(!failures, "there should not have been any failures");
3466 } else {
3467 if (!silent) {
3468 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3469 if (G1StringDedup::is_enabled()) {
3470 gclog_or_tty->print(", StrDedup");
3471 }
3472 gclog_or_tty->print(") ");
3473 }
3474 }
3475 }
3476
3477 void G1CollectedHeap::verify(bool silent) {
3478 verify(silent, VerifyOption_G1UsePrevMarking);
3479 }
3480
3481 double G1CollectedHeap::verify(bool guard, const char* msg) {
3482 double verify_time_ms = 0.0;
3483
3484 if (guard && total_collections() >= VerifyGCStartAt) {
3485 double verify_start = os::elapsedTime();
3486 HandleMark hm; // Discard invalid handles created during verification
3487 prepare_for_verify();
3488 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3489 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3490 }
3491
3492 return verify_time_ms;
3493 }
3494
3495 void G1CollectedHeap::verify_before_gc() {
3496 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3497 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3498 }
3499
3500 void G1CollectedHeap::verify_after_gc() {
3501 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3502 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3503 }
3504
3505 class PrintRegionClosure: public HeapRegionClosure {
3506 outputStream* _st;
3507 public:
3508 PrintRegionClosure(outputStream* st) : _st(st) {}
3509 bool doHeapRegion(HeapRegion* r) {
3510 r->print_on(_st);
3511 return false;
3512 }
3513 };
3514
3515 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3516 const HeapRegion* hr,
3517 const VerifyOption vo) const {
3518 switch (vo) {
3519 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3520 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3521 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3522 default: ShouldNotReachHere();
3523 }
3524 return false; // keep some compilers happy
3525 }
3526
3527 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3528 const VerifyOption vo) const {
3529 switch (vo) {
3530 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3531 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3532 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3533 default: ShouldNotReachHere();
3534 }
3535 return false; // keep some compilers happy
3536 }
3537
3538 void G1CollectedHeap::print_on(outputStream* st) const {
3539 st->print(" %-20s", "garbage-first heap");
3540 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3541 capacity()/K, used_unlocked()/K);
3542 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3543 _g1_storage.low_boundary(),
3544 _g1_storage.high(),
3545 _g1_storage.high_boundary());
3546 st->cr();
3547 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3548 uint young_regions = _young_list->length();
3549 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3550 (size_t) young_regions * HeapRegion::GrainBytes / K);
3551 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3552 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3553 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3554 st->cr();
3555 MetaspaceAux::print_on(st);
3556 }
3557
3558 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3559 print_on(st);
3560
3561 // Print the per-region information.
3562 st->cr();
3563 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3564 "HS=humongous(starts), HC=humongous(continues), "
3565 "CS=collection set, F=free, TS=gc time stamp, "
3566 "PTAMS=previous top-at-mark-start, "
3567 "NTAMS=next top-at-mark-start)");
3568 PrintRegionClosure blk(st);
3569 heap_region_iterate(&blk);
3570 }
3571
3572 void G1CollectedHeap::print_on_error(outputStream* st) const {
3573 this->CollectedHeap::print_on_error(st);
3574
3575 if (_cm != NULL) {
3576 st->cr();
3577 _cm->print_on_error(st);
3578 }
3579 }
3580
3581 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3582 if (G1CollectedHeap::use_parallel_gc_threads()) {
3583 workers()->print_worker_threads_on(st);
3584 }
3585 _cmThread->print_on(st);
3586 st->cr();
3587 _cm->print_worker_threads_on(st);
3588 _cg1r->print_worker_threads_on(st);
3589 if (G1StringDedup::is_enabled()) {
3590 G1StringDedup::print_worker_threads_on(st);
3591 }
3592 }
3593
3594 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3595 if (G1CollectedHeap::use_parallel_gc_threads()) {
3596 workers()->threads_do(tc);
3597 }
3598 tc->do_thread(_cmThread);
3599 _cg1r->threads_do(tc);
3600 if (G1StringDedup::is_enabled()) {
3601 G1StringDedup::threads_do(tc);
3602 }
3603 }
3604
3605 void G1CollectedHeap::print_tracing_info() const {
3606 // We'll overload this to mean "trace GC pause statistics."
3607 if (TraceGen0Time || TraceGen1Time) {
3608 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3609 // to that.
3610 g1_policy()->print_tracing_info();
3611 }
3612 if (G1SummarizeRSetStats) {
3613 g1_rem_set()->print_summary_info();
3614 }
3615 if (G1SummarizeConcMark) {
3616 concurrent_mark()->print_summary_info();
3617 }
3618 g1_policy()->print_yg_surv_rate_info();
3619 SpecializationStats::print();
3620 }
3621
3622 #ifndef PRODUCT
3623 // Helpful for debugging RSet issues.
3624
3625 class PrintRSetsClosure : public HeapRegionClosure {
3626 private:
3627 const char* _msg;
3628 size_t _occupied_sum;
3629
3630 public:
3631 bool doHeapRegion(HeapRegion* r) {
3632 HeapRegionRemSet* hrrs = r->rem_set();
3633 size_t occupied = hrrs->occupied();
3634 _occupied_sum += occupied;
3635
3636 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3637 HR_FORMAT_PARAMS(r));
3638 if (occupied == 0) {
3639 gclog_or_tty->print_cr(" RSet is empty");
3640 } else {
3641 hrrs->print();
3642 }
3643 gclog_or_tty->print_cr("----------");
3644 return false;
3645 }
3646
3647 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3648 gclog_or_tty->cr();
3649 gclog_or_tty->print_cr("========================================");
3650 gclog_or_tty->print_cr(msg);
3651 gclog_or_tty->cr();
3652 }
3653
3654 ~PrintRSetsClosure() {
3655 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3656 gclog_or_tty->print_cr("========================================");
3657 gclog_or_tty->cr();
3658 }
3659 };
3660
3661 void G1CollectedHeap::print_cset_rsets() {
3662 PrintRSetsClosure cl("Printing CSet RSets");
3663 collection_set_iterate(&cl);
3664 }
3665
3666 void G1CollectedHeap::print_all_rsets() {
3667 PrintRSetsClosure cl("Printing All RSets");;
3668 heap_region_iterate(&cl);
3669 }
3670 #endif // PRODUCT
3671
3672 G1CollectedHeap* G1CollectedHeap::heap() {
3673 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3674 "not a garbage-first heap");
3675 return _g1h;
3676 }
3677
3678 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3679 // always_do_update_barrier = false;
3680 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3681 // Fill TLAB's and such
3682 accumulate_statistics_all_tlabs();
3683 ensure_parsability(true);
3684
3685 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3686 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3687 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3688 }
3689 }
3690
3691 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3692
3693 if (G1SummarizeRSetStats &&
3694 (G1SummarizeRSetStatsPeriod > 0) &&
3695 // we are at the end of the GC. Total collections has already been increased.
3696 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3697 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3698 }
3699
3700 // FIXME: what is this about?
3701 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3702 // is set.
3703 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3704 "derived pointer present"));
3705 // always_do_update_barrier = true;
3706
3707 resize_all_tlabs();
3708
3709 // We have just completed a GC. Update the soft reference
3710 // policy with the new heap occupancy
3711 Universe::update_heap_info_at_gc();
3712 }
3713
3714 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3715 unsigned int gc_count_before,
3716 bool* succeeded,
3717 GCCause::Cause gc_cause) {
3718 assert_heap_not_locked_and_not_at_safepoint();
3719 g1_policy()->record_stop_world_start();
3720 VM_G1IncCollectionPause op(gc_count_before,
3721 word_size,
3722 false, /* should_initiate_conc_mark */
3723 g1_policy()->max_pause_time_ms(),
3724 gc_cause);
3725 VMThread::execute(&op);
3726
3727 HeapWord* result = op.result();
3728 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3729 assert(result == NULL || ret_succeeded,
3730 "the result should be NULL if the VM did not succeed");
3731 *succeeded = ret_succeeded;
3732
3733 assert_heap_not_locked();
3734 return result;
3735 }
3736
3737 void
3738 G1CollectedHeap::doConcurrentMark() {
3739 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3740 if (!_cmThread->in_progress()) {
3741 _cmThread->set_started();
3742 CGC_lock->notify();
3743 }
3744 }
3745
3746 size_t G1CollectedHeap::pending_card_num() {
3747 size_t extra_cards = 0;
3748 JavaThread *curr = Threads::first();
3749 while (curr != NULL) {
3750 DirtyCardQueue& dcq = curr->dirty_card_queue();
3751 extra_cards += dcq.size();
3752 curr = curr->next();
3753 }
3754 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3755 size_t buffer_size = dcqs.buffer_size();
3756 size_t buffer_num = dcqs.completed_buffers_num();
3757
3758 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3759 // in bytes - not the number of 'entries'. We need to convert
3760 // into a number of cards.
3761 return (buffer_size * buffer_num + extra_cards) / oopSize;
3762 }
3763
3764 size_t G1CollectedHeap::cards_scanned() {
3765 return g1_rem_set()->cardsScanned();
3766 }
3767
3768 void
3769 G1CollectedHeap::setup_surviving_young_words() {
3770 assert(_surviving_young_words == NULL, "pre-condition");
3771 uint array_length = g1_policy()->young_cset_region_length();
3772 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3773 if (_surviving_young_words == NULL) {
3774 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3775 "Not enough space for young surv words summary.");
3776 }
3777 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3778 #ifdef ASSERT
3779 for (uint i = 0; i < array_length; ++i) {
3780 assert( _surviving_young_words[i] == 0, "memset above" );
3781 }
3782 #endif // !ASSERT
3783 }
3784
3785 void
3786 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3787 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3788 uint array_length = g1_policy()->young_cset_region_length();
3789 for (uint i = 0; i < array_length; ++i) {
3790 _surviving_young_words[i] += surv_young_words[i];
3791 }
3792 }
3793
3794 void
3795 G1CollectedHeap::cleanup_surviving_young_words() {
3796 guarantee( _surviving_young_words != NULL, "pre-condition" );
3797 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3798 _surviving_young_words = NULL;
3799 }
3800
3801 #ifdef ASSERT
3802 class VerifyCSetClosure: public HeapRegionClosure {
3803 public:
3804 bool doHeapRegion(HeapRegion* hr) {
3805 // Here we check that the CSet region's RSet is ready for parallel
3806 // iteration. The fields that we'll verify are only manipulated
3807 // when the region is part of a CSet and is collected. Afterwards,
3808 // we reset these fields when we clear the region's RSet (when the
3809 // region is freed) so they are ready when the region is
3810 // re-allocated. The only exception to this is if there's an
3811 // evacuation failure and instead of freeing the region we leave
3812 // it in the heap. In that case, we reset these fields during
3813 // evacuation failure handling.
3814 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3815
3816 // Here's a good place to add any other checks we'd like to
3817 // perform on CSet regions.
3818 return false;
3819 }
3820 };
3821 #endif // ASSERT
3822
3823 #if TASKQUEUE_STATS
3824 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3825 st->print_raw_cr("GC Task Stats");
3826 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3827 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3828 }
3829
3830 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3831 print_taskqueue_stats_hdr(st);
3832
3833 TaskQueueStats totals;
3834 const int n = workers() != NULL ? workers()->total_workers() : 1;
3835 for (int i = 0; i < n; ++i) {
3836 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3837 totals += task_queue(i)->stats;
3838 }
3839 st->print_raw("tot "); totals.print(st); st->cr();
3840
3841 DEBUG_ONLY(totals.verify());
3842 }
3843
3844 void G1CollectedHeap::reset_taskqueue_stats() {
3845 const int n = workers() != NULL ? workers()->total_workers() : 1;
3846 for (int i = 0; i < n; ++i) {
3847 task_queue(i)->stats.reset();
3848 }
3849 }
3850 #endif // TASKQUEUE_STATS
3851
3852 void G1CollectedHeap::log_gc_header() {
3853 if (!G1Log::fine()) {
3854 return;
3855 }
3856
3857 gclog_or_tty->date_stamp(PrintGCDateStamps);
3858 gclog_or_tty->stamp(PrintGCTimeStamps);
3859
3860 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3861 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3862 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3863
3864 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3865 }
3866
3867 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3868 if (!G1Log::fine()) {
3869 return;
3870 }
3871
3872 if (G1Log::finer()) {
3873 if (evacuation_failed()) {
3874 gclog_or_tty->print(" (to-space exhausted)");
3875 }
3876 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3877 g1_policy()->phase_times()->note_gc_end();
3878 g1_policy()->phase_times()->print(pause_time_sec);
3879 g1_policy()->print_detailed_heap_transition();
3880 } else {
3881 if (evacuation_failed()) {
3882 gclog_or_tty->print("--");
3883 }
3884 g1_policy()->print_heap_transition();
3885 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3886 }
3887 gclog_or_tty->flush();
3888 }
3889
3890 bool
3891 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3892 assert_at_safepoint(true /* should_be_vm_thread */);
3893 guarantee(!is_gc_active(), "collection is not reentrant");
3894
3895 if (GC_locker::check_active_before_gc()) {
3896 return false;
3897 }
3898
3899 _gc_timer_stw->register_gc_start();
3900
3901 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3902
3903 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3904 ResourceMark rm;
3905
3906 print_heap_before_gc();
3907 trace_heap_before_gc(_gc_tracer_stw);
3908
3909 verify_region_sets_optional();
3910 verify_dirty_young_regions();
3911
3912 // This call will decide whether this pause is an initial-mark
3913 // pause. If it is, during_initial_mark_pause() will return true
3914 // for the duration of this pause.
3915 g1_policy()->decide_on_conc_mark_initiation();
3916
3917 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3918 assert(!g1_policy()->during_initial_mark_pause() ||
3919 g1_policy()->gcs_are_young(), "sanity");
3920
3921 // We also do not allow mixed GCs during marking.
3922 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3923
3924 // Record whether this pause is an initial mark. When the current
3925 // thread has completed its logging output and it's safe to signal
3926 // the CM thread, the flag's value in the policy has been reset.
3927 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3928
3929 // Inner scope for scope based logging, timers, and stats collection
3930 {
3931 EvacuationInfo evacuation_info;
3932
3933 if (g1_policy()->during_initial_mark_pause()) {
3934 // We are about to start a marking cycle, so we increment the
3935 // full collection counter.
3936 increment_old_marking_cycles_started();
3937 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3938 }
3939
3940 _gc_tracer_stw->report_yc_type(yc_type());
3941
3942 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3943
3944 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3945 workers()->active_workers() : 1);
3946 double pause_start_sec = os::elapsedTime();
3947 g1_policy()->phase_times()->note_gc_start(active_workers);
3948 log_gc_header();
3949
3950 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3951 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3952
3953 // If the secondary_free_list is not empty, append it to the
3954 // free_list. No need to wait for the cleanup operation to finish;
3955 // the region allocation code will check the secondary_free_list
3956 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3957 // set, skip this step so that the region allocation code has to
3958 // get entries from the secondary_free_list.
3959 if (!G1StressConcRegionFreeing) {
3960 append_secondary_free_list_if_not_empty_with_lock();
3961 }
3962
3963 assert(check_young_list_well_formed(), "young list should be well formed");
3964 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3965 "sanity check");
3966
3967 // Don't dynamically change the number of GC threads this early. A value of
3968 // 0 is used to indicate serial work. When parallel work is done,
3969 // it will be set.
3970
3971 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3972 IsGCActiveMark x;
3973
3974 gc_prologue(false);
3975 increment_total_collections(false /* full gc */);
3976 increment_gc_time_stamp();
3977
3978 verify_before_gc();
3979
3980 COMPILER2_PRESENT(DerivedPointerTable::clear());
3981
3982 // Please see comment in g1CollectedHeap.hpp and
3983 // G1CollectedHeap::ref_processing_init() to see how
3984 // reference processing currently works in G1.
3985
3986 // Enable discovery in the STW reference processor
3987 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3988 true /*verify_no_refs*/);
3989
3990 {
3991 // We want to temporarily turn off discovery by the
3992 // CM ref processor, if necessary, and turn it back on
3993 // on again later if we do. Using a scoped
3994 // NoRefDiscovery object will do this.
3995 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3996
3997 // Forget the current alloc region (we might even choose it to be part
3998 // of the collection set!).
3999 release_mutator_alloc_region();
4000
4001 // We should call this after we retire the mutator alloc
4002 // region(s) so that all the ALLOC / RETIRE events are generated
4003 // before the start GC event.
4004 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4005
4006 // This timing is only used by the ergonomics to handle our pause target.
4007 // It is unclear why this should not include the full pause. We will
4008 // investigate this in CR 7178365.
4009 //
4010 // Preserving the old comment here if that helps the investigation:
4011 //
4012 // The elapsed time induced by the start time below deliberately elides
4013 // the possible verification above.
4014 double sample_start_time_sec = os::elapsedTime();
4015
4016 #if YOUNG_LIST_VERBOSE
4017 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4018 _young_list->print();
4019 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4020 #endif // YOUNG_LIST_VERBOSE
4021
4022 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4023
4024 double scan_wait_start = os::elapsedTime();
4025 // We have to wait until the CM threads finish scanning the
4026 // root regions as it's the only way to ensure that all the
4027 // objects on them have been correctly scanned before we start
4028 // moving them during the GC.
4029 bool waited = _cm->root_regions()->wait_until_scan_finished();
4030 double wait_time_ms = 0.0;
4031 if (waited) {
4032 double scan_wait_end = os::elapsedTime();
4033 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4034 }
4035 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4036
4037 #if YOUNG_LIST_VERBOSE
4038 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4039 _young_list->print();
4040 #endif // YOUNG_LIST_VERBOSE
4041
4042 if (g1_policy()->during_initial_mark_pause()) {
4043 concurrent_mark()->checkpointRootsInitialPre();
4044 }
4045
4046 #if YOUNG_LIST_VERBOSE
4047 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4048 _young_list->print();
4049 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4050 #endif // YOUNG_LIST_VERBOSE
4051
4052 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4053
4054 _cm->note_start_of_gc();
4055 // We should not verify the per-thread SATB buffers given that
4056 // we have not filtered them yet (we'll do so during the
4057 // GC). We also call this after finalize_cset() to
4058 // ensure that the CSet has been finalized.
4059 _cm->verify_no_cset_oops(true /* verify_stacks */,
4060 true /* verify_enqueued_buffers */,
4061 false /* verify_thread_buffers */,
4062 true /* verify_fingers */);
4063
4064 if (_hr_printer.is_active()) {
4065 HeapRegion* hr = g1_policy()->collection_set();
4066 while (hr != NULL) {
4067 G1HRPrinter::RegionType type;
4068 if (!hr->is_young()) {
4069 type = G1HRPrinter::Old;
4070 } else if (hr->is_survivor()) {
4071 type = G1HRPrinter::Survivor;
4072 } else {
4073 type = G1HRPrinter::Eden;
4074 }
4075 _hr_printer.cset(hr);
4076 hr = hr->next_in_collection_set();
4077 }
4078 }
4079
4080 #ifdef ASSERT
4081 VerifyCSetClosure cl;
4082 collection_set_iterate(&cl);
4083 #endif // ASSERT
4084
4085 setup_surviving_young_words();
4086
4087 // Initialize the GC alloc regions.
4088 init_gc_alloc_regions(evacuation_info);
4089
4090 // Actually do the work...
4091 evacuate_collection_set(evacuation_info);
4092
4093 // We do this to mainly verify the per-thread SATB buffers
4094 // (which have been filtered by now) since we didn't verify
4095 // them earlier. No point in re-checking the stacks / enqueued
4096 // buffers given that the CSet has not changed since last time
4097 // we checked.
4098 _cm->verify_no_cset_oops(false /* verify_stacks */,
4099 false /* verify_enqueued_buffers */,
4100 true /* verify_thread_buffers */,
4101 true /* verify_fingers */);
4102
4103 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4104 g1_policy()->clear_collection_set();
4105
4106 cleanup_surviving_young_words();
4107
4108 // Start a new incremental collection set for the next pause.
4109 g1_policy()->start_incremental_cset_building();
4110
4111 clear_cset_fast_test();
4112
4113 _young_list->reset_sampled_info();
4114
4115 // Don't check the whole heap at this point as the
4116 // GC alloc regions from this pause have been tagged
4117 // as survivors and moved on to the survivor list.
4118 // Survivor regions will fail the !is_young() check.
4119 assert(check_young_list_empty(false /* check_heap */),
4120 "young list should be empty");
4121
4122 #if YOUNG_LIST_VERBOSE
4123 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4124 _young_list->print();
4125 #endif // YOUNG_LIST_VERBOSE
4126
4127 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4128 _young_list->first_survivor_region(),
4129 _young_list->last_survivor_region());
4130
4131 _young_list->reset_auxilary_lists();
4132
4133 if (evacuation_failed()) {
4134 _summary_bytes_used = recalculate_used();
4135 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4136 for (uint i = 0; i < n_queues; i++) {
4137 if (_evacuation_failed_info_array[i].has_failed()) {
4138 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4139 }
4140 }
4141 } else {
4142 // The "used" of the the collection set have already been subtracted
4143 // when they were freed. Add in the bytes evacuated.
4144 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4145 }
4146
4147 if (g1_policy()->during_initial_mark_pause()) {
4148 // We have to do this before we notify the CM threads that
4149 // they can start working to make sure that all the
4150 // appropriate initialization is done on the CM object.
4151 concurrent_mark()->checkpointRootsInitialPost();
4152 set_marking_started();
4153 // Note that we don't actually trigger the CM thread at
4154 // this point. We do that later when we're sure that
4155 // the current thread has completed its logging output.
4156 }
4157
4158 allocate_dummy_regions();
4159
4160 #if YOUNG_LIST_VERBOSE
4161 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4162 _young_list->print();
4163 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4164 #endif // YOUNG_LIST_VERBOSE
4165
4166 init_mutator_alloc_region();
4167
4168 {
4169 size_t expand_bytes = g1_policy()->expansion_amount();
4170 if (expand_bytes > 0) {
4171 size_t bytes_before = capacity();
4172 // No need for an ergo verbose message here,
4173 // expansion_amount() does this when it returns a value > 0.
4174 if (!expand(expand_bytes)) {
4175 // We failed to expand the heap so let's verify that
4176 // committed/uncommitted amount match the backing store
4177 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4178 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4179 }
4180 }
4181 }
4182
4183 // We redo the verification but now wrt to the new CSet which
4184 // has just got initialized after the previous CSet was freed.
4185 _cm->verify_no_cset_oops(true /* verify_stacks */,
4186 true /* verify_enqueued_buffers */,
4187 true /* verify_thread_buffers */,
4188 true /* verify_fingers */);
4189 _cm->note_end_of_gc();
4190
4191 // This timing is only used by the ergonomics to handle our pause target.
4192 // It is unclear why this should not include the full pause. We will
4193 // investigate this in CR 7178365.
4194 double sample_end_time_sec = os::elapsedTime();
4195 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4196 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4197
4198 MemoryService::track_memory_usage();
4199
4200 // In prepare_for_verify() below we'll need to scan the deferred
4201 // update buffers to bring the RSets up-to-date if
4202 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4203 // the update buffers we'll probably need to scan cards on the
4204 // regions we just allocated to (i.e., the GC alloc
4205 // regions). However, during the last GC we called
4206 // set_saved_mark() on all the GC alloc regions, so card
4207 // scanning might skip the [saved_mark_word()...top()] area of
4208 // those regions (i.e., the area we allocated objects into
4209 // during the last GC). But it shouldn't. Given that
4210 // saved_mark_word() is conditional on whether the GC time stamp
4211 // on the region is current or not, by incrementing the GC time
4212 // stamp here we invalidate all the GC time stamps on all the
4213 // regions and saved_mark_word() will simply return top() for
4214 // all the regions. This is a nicer way of ensuring this rather
4215 // than iterating over the regions and fixing them. In fact, the
4216 // GC time stamp increment here also ensures that
4217 // saved_mark_word() will return top() between pauses, i.e.,
4218 // during concurrent refinement. So we don't need the
4219 // is_gc_active() check to decided which top to use when
4220 // scanning cards (see CR 7039627).
4221 increment_gc_time_stamp();
4222
4223 verify_after_gc();
4224
4225 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4226 ref_processor_stw()->verify_no_references_recorded();
4227
4228 // CM reference discovery will be re-enabled if necessary.
4229 }
4230
4231 // We should do this after we potentially expand the heap so
4232 // that all the COMMIT events are generated before the end GC
4233 // event, and after we retire the GC alloc regions so that all
4234 // RETIRE events are generated before the end GC event.
4235 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4236
4237 if (mark_in_progress()) {
4238 concurrent_mark()->update_g1_committed();
4239 }
4240
4241 #ifdef TRACESPINNING
4242 ParallelTaskTerminator::print_termination_counts();
4243 #endif
4244
4245 gc_epilogue(false);
4246 }
4247
4248 // Print the remainder of the GC log output.
4249 log_gc_footer(os::elapsedTime() - pause_start_sec);
4250
4251 // It is not yet to safe to tell the concurrent mark to
4252 // start as we have some optional output below. We don't want the
4253 // output from the concurrent mark thread interfering with this
4254 // logging output either.
4255
4256 _hrs.verify_optional();
4257 verify_region_sets_optional();
4258
4259 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4260 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4261
4262 print_heap_after_gc();
4263 trace_heap_after_gc(_gc_tracer_stw);
4264
4265 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4266 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4267 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4268 // before any GC notifications are raised.
4269 g1mm()->update_sizes();
4270
4271 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4272 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4273 _gc_timer_stw->register_gc_end();
4274 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4275 }
4276 // It should now be safe to tell the concurrent mark thread to start
4277 // without its logging output interfering with the logging output
4278 // that came from the pause.
4279
4280 if (should_start_conc_mark) {
4281 // CAUTION: after the doConcurrentMark() call below,
4282 // the concurrent marking thread(s) could be running
4283 // concurrently with us. Make sure that anything after
4284 // this point does not assume that we are the only GC thread
4285 // running. Note: of course, the actual marking work will
4286 // not start until the safepoint itself is released in
4287 // ConcurrentGCThread::safepoint_desynchronize().
4288 doConcurrentMark();
4289 }
4290
4291 return true;
4292 }
4293
4294 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4295 {
4296 size_t gclab_word_size;
4297 switch (purpose) {
4298 case GCAllocForSurvived:
4299 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4300 break;
4301 case GCAllocForTenured:
4302 gclab_word_size = _old_plab_stats.desired_plab_sz();
4303 break;
4304 default:
4305 assert(false, "unknown GCAllocPurpose");
4306 gclab_word_size = _old_plab_stats.desired_plab_sz();
4307 break;
4308 }
4309
4310 // Prevent humongous PLAB sizes for two reasons:
4311 // * PLABs are allocated using a similar paths as oops, but should
4312 // never be in a humongous region
4313 // * Allowing humongous PLABs needlessly churns the region free lists
4314 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4315 }
4316
4317 void G1CollectedHeap::init_mutator_alloc_region() {
4318 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4319 _mutator_alloc_region.init();
4320 }
4321
4322 void G1CollectedHeap::release_mutator_alloc_region() {
4323 _mutator_alloc_region.release();
4324 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4325 }
4326
4327 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4328 assert_at_safepoint(true /* should_be_vm_thread */);
4329
4330 _survivor_gc_alloc_region.init();
4331 _old_gc_alloc_region.init();
4332 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4333 _retained_old_gc_alloc_region = NULL;
4334
4335 // We will discard the current GC alloc region if:
4336 // a) it's in the collection set (it can happen!),
4337 // b) it's already full (no point in using it),
4338 // c) it's empty (this means that it was emptied during
4339 // a cleanup and it should be on the free list now), or
4340 // d) it's humongous (this means that it was emptied
4341 // during a cleanup and was added to the free list, but
4342 // has been subsequently used to allocate a humongous
4343 // object that may be less than the region size).
4344 if (retained_region != NULL &&
4345 !retained_region->in_collection_set() &&
4346 !(retained_region->top() == retained_region->end()) &&
4347 !retained_region->is_empty() &&
4348 !retained_region->isHumongous()) {
4349 retained_region->set_saved_mark();
4350 // The retained region was added to the old region set when it was
4351 // retired. We have to remove it now, since we don't allow regions
4352 // we allocate to in the region sets. We'll re-add it later, when
4353 // it's retired again.
4354 _old_set.remove(retained_region);
4355 bool during_im = g1_policy()->during_initial_mark_pause();
4356 retained_region->note_start_of_copying(during_im);
4357 _old_gc_alloc_region.set(retained_region);
4358 _hr_printer.reuse(retained_region);
4359 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4360 }
4361 }
4362
4363 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4364 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4365 _old_gc_alloc_region.count());
4366 _survivor_gc_alloc_region.release();
4367 // If we have an old GC alloc region to release, we'll save it in
4368 // _retained_old_gc_alloc_region. If we don't
4369 // _retained_old_gc_alloc_region will become NULL. This is what we
4370 // want either way so no reason to check explicitly for either
4371 // condition.
4372 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4373
4374 if (ResizePLAB) {
4375 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4376 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4377 }
4378 }
4379
4380 void G1CollectedHeap::abandon_gc_alloc_regions() {
4381 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4382 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4383 _retained_old_gc_alloc_region = NULL;
4384 }
4385
4386 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4387 _drain_in_progress = false;
4388 set_evac_failure_closure(cl);
4389 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4390 }
4391
4392 void G1CollectedHeap::finalize_for_evac_failure() {
4393 assert(_evac_failure_scan_stack != NULL &&
4394 _evac_failure_scan_stack->length() == 0,
4395 "Postcondition");
4396 assert(!_drain_in_progress, "Postcondition");
4397 delete _evac_failure_scan_stack;
4398 _evac_failure_scan_stack = NULL;
4399 }
4400
4401 void G1CollectedHeap::remove_self_forwarding_pointers() {
4402 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4403
4404 double remove_self_forwards_start = os::elapsedTime();
4405
4406 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4407
4408 if (G1CollectedHeap::use_parallel_gc_threads()) {
4409 set_par_threads();
4410 workers()->run_task(&rsfp_task);
4411 set_par_threads(0);
4412 } else {
4413 rsfp_task.work(0);
4414 }
4415
4416 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4417
4418 // Reset the claim values in the regions in the collection set.
4419 reset_cset_heap_region_claim_values();
4420
4421 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4422
4423 // Now restore saved marks, if any.
4424 assert(_objs_with_preserved_marks.size() ==
4425 _preserved_marks_of_objs.size(), "Both or none.");
4426 while (!_objs_with_preserved_marks.is_empty()) {
4427 oop obj = _objs_with_preserved_marks.pop();
4428 markOop m = _preserved_marks_of_objs.pop();
4429 obj->set_mark(m);
4430 }
4431 _objs_with_preserved_marks.clear(true);
4432 _preserved_marks_of_objs.clear(true);
4433
4434 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4435 }
4436
4437 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4438 _evac_failure_scan_stack->push(obj);
4439 }
4440
4441 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4442 assert(_evac_failure_scan_stack != NULL, "precondition");
4443
4444 while (_evac_failure_scan_stack->length() > 0) {
4445 oop obj = _evac_failure_scan_stack->pop();
4446 _evac_failure_closure->set_region(heap_region_containing(obj));
4447 obj->oop_iterate_backwards(_evac_failure_closure);
4448 }
4449 }
4450
4451 oop
4452 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4453 oop old) {
4454 assert(obj_in_cs(old),
4455 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4456 (HeapWord*) old));
4457 markOop m = old->mark();
4458 oop forward_ptr = old->forward_to_atomic(old);
4459 if (forward_ptr == NULL) {
4460 // Forward-to-self succeeded.
4461 assert(_par_scan_state != NULL, "par scan state");
4462 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4463 uint queue_num = _par_scan_state->queue_num();
4464
4465 _evacuation_failed = true;
4466 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4467 if (_evac_failure_closure != cl) {
4468 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4469 assert(!_drain_in_progress,
4470 "Should only be true while someone holds the lock.");
4471 // Set the global evac-failure closure to the current thread's.
4472 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4473 set_evac_failure_closure(cl);
4474 // Now do the common part.
4475 handle_evacuation_failure_common(old, m);
4476 // Reset to NULL.
4477 set_evac_failure_closure(NULL);
4478 } else {
4479 // The lock is already held, and this is recursive.
4480 assert(_drain_in_progress, "This should only be the recursive case.");
4481 handle_evacuation_failure_common(old, m);
4482 }
4483 return old;
4484 } else {
4485 // Forward-to-self failed. Either someone else managed to allocate
4486 // space for this object (old != forward_ptr) or they beat us in
4487 // self-forwarding it (old == forward_ptr).
4488 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4489 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4490 "should not be in the CSet",
4491 (HeapWord*) old, (HeapWord*) forward_ptr));
4492 return forward_ptr;
4493 }
4494 }
4495
4496 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4497 preserve_mark_if_necessary(old, m);
4498
4499 HeapRegion* r = heap_region_containing(old);
4500 if (!r->evacuation_failed()) {
4501 r->set_evacuation_failed(true);
4502 _hr_printer.evac_failure(r);
4503 }
4504
4505 push_on_evac_failure_scan_stack(old);
4506
4507 if (!_drain_in_progress) {
4508 // prevent recursion in copy_to_survivor_space()
4509 _drain_in_progress = true;
4510 drain_evac_failure_scan_stack();
4511 _drain_in_progress = false;
4512 }
4513 }
4514
4515 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4516 assert(evacuation_failed(), "Oversaving!");
4517 // We want to call the "for_promotion_failure" version only in the
4518 // case of a promotion failure.
4519 if (m->must_be_preserved_for_promotion_failure(obj)) {
4520 _objs_with_preserved_marks.push(obj);
4521 _preserved_marks_of_objs.push(m);
4522 }
4523 }
4524
4525 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4526 size_t word_size) {
4527 if (purpose == GCAllocForSurvived) {
4528 HeapWord* result = survivor_attempt_allocation(word_size);
4529 if (result != NULL) {
4530 return result;
4531 } else {
4532 // Let's try to allocate in the old gen in case we can fit the
4533 // object there.
4534 return old_attempt_allocation(word_size);
4535 }
4536 } else {
4537 assert(purpose == GCAllocForTenured, "sanity");
4538 HeapWord* result = old_attempt_allocation(word_size);
4539 if (result != NULL) {
4540 return result;
4541 } else {
4542 // Let's try to allocate in the survivors in case we can fit the
4543 // object there.
4544 return survivor_attempt_allocation(word_size);
4545 }
4546 }
4547
4548 ShouldNotReachHere();
4549 // Trying to keep some compilers happy.
4550 return NULL;
4551 }
4552
4553 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4554 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4555
4556 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4557 : _g1h(g1h),
4558 _refs(g1h->task_queue(queue_num)),
4559 _dcq(&g1h->dirty_card_queue_set()),
4560 _ct_bs(g1h->g1_barrier_set()),
4561 _g1_rem(g1h->g1_rem_set()),
4562 _hash_seed(17), _queue_num(queue_num),
4563 _term_attempts(0),
4564 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4565 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4566 _age_table(false), _scanner(g1h, this, rp),
4567 _strong_roots_time(0), _term_time(0),
4568 _alloc_buffer_waste(0), _undo_waste(0) {
4569 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4570 // we "sacrifice" entry 0 to keep track of surviving bytes for
4571 // non-young regions (where the age is -1)
4572 // We also add a few elements at the beginning and at the end in
4573 // an attempt to eliminate cache contention
4574 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4575 uint array_length = PADDING_ELEM_NUM +
4576 real_length +
4577 PADDING_ELEM_NUM;
4578 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4579 if (_surviving_young_words_base == NULL)
4580 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4581 "Not enough space for young surv histo.");
4582 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4583 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4584
4585 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4586 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4587
4588 _start = os::elapsedTime();
4589 }
4590
4591 void
4592 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4593 {
4594 st->print_raw_cr("GC Termination Stats");
4595 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4596 " ------waste (KiB)------");
4597 st->print_raw_cr("thr ms ms % ms % attempts"
4598 " total alloc undo");
4599 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4600 " ------- ------- -------");
4601 }
4602
4603 void
4604 G1ParScanThreadState::print_termination_stats(int i,
4605 outputStream* const st) const
4606 {
4607 const double elapsed_ms = elapsed_time() * 1000.0;
4608 const double s_roots_ms = strong_roots_time() * 1000.0;
4609 const double term_ms = term_time() * 1000.0;
4610 st->print_cr("%3d %9.2f %9.2f %6.2f "
4611 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4612 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4613 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4614 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4615 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4616 alloc_buffer_waste() * HeapWordSize / K,
4617 undo_waste() * HeapWordSize / K);
4618 }
4619
4620 #ifdef ASSERT
4621 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4622 assert(ref != NULL, "invariant");
4623 assert(UseCompressedOops, "sanity");
4624 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4625 oop p = oopDesc::load_decode_heap_oop(ref);
4626 assert(_g1h->is_in_g1_reserved(p),
4627 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4628 return true;
4629 }
4630
4631 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4632 assert(ref != NULL, "invariant");
4633 if (has_partial_array_mask(ref)) {
4634 // Must be in the collection set--it's already been copied.
4635 oop p = clear_partial_array_mask(ref);
4636 assert(_g1h->obj_in_cs(p),
4637 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4638 } else {
4639 oop p = oopDesc::load_decode_heap_oop(ref);
4640 assert(_g1h->is_in_g1_reserved(p),
4641 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4642 }
4643 return true;
4644 }
4645
4646 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4647 if (ref.is_narrow()) {
4648 return verify_ref((narrowOop*) ref);
4649 } else {
4650 return verify_ref((oop*) ref);
4651 }
4652 }
4653 #endif // ASSERT
4654
4655 void G1ParScanThreadState::trim_queue() {
4656 assert(_evac_failure_cl != NULL, "not set");
4657
4658 StarTask ref;
4659 do {
4660 // Drain the overflow stack first, so other threads can steal.
4661 while (refs()->pop_overflow(ref)) {
4662 deal_with_reference(ref);
4663 }
4664
4665 while (refs()->pop_local(ref)) {
4666 deal_with_reference(ref);
4667 }
4668 } while (!refs()->is_empty());
4669 }
4670
4671 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4672 G1ParScanThreadState* par_scan_state) :
4673 _g1(g1), _par_scan_state(par_scan_state),
4674 _worker_id(par_scan_state->queue_num()) { }
4675
4676 void G1ParCopyHelper::mark_object(oop obj) {
4677 #ifdef ASSERT
4678 HeapRegion* hr = _g1->heap_region_containing(obj);
4679 assert(hr != NULL, "sanity");
4680 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4681 #endif // ASSERT
4682
4683 // We know that the object is not moving so it's safe to read its size.
4684 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4685 }
4686
4687 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4688 #ifdef ASSERT
4689 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4690 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4691 assert(from_obj != to_obj, "should not be self-forwarded");
4692
4693 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4694 assert(from_hr != NULL, "sanity");
4695 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4696
4697 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4698 assert(to_hr != NULL, "sanity");
4699 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4700 #endif // ASSERT
4701
4702 // The object might be in the process of being copied by another
4703 // worker so we cannot trust that its to-space image is
4704 // well-formed. So we have to read its size from its from-space
4705 // image which we know should not be changing.
4706 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4707 }
4708
4709 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4710 size_t word_sz = old->size();
4711 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4712 // +1 to make the -1 indexes valid...
4713 int young_index = from_region->young_index_in_cset()+1;
4714 assert( (from_region->is_young() && young_index > 0) ||
4715 (!from_region->is_young() && young_index == 0), "invariant" );
4716 G1CollectorPolicy* g1p = _g1h->g1_policy();
4717 markOop m = old->mark();
4718 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4719 : m->age();
4720 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4721 word_sz);
4722 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4723 #ifndef PRODUCT
4724 // Should this evacuation fail?
4725 if (_g1h->evacuation_should_fail()) {
4726 if (obj_ptr != NULL) {
4727 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4728 obj_ptr = NULL;
4729 }
4730 }
4731 #endif // !PRODUCT
4732
4733 if (obj_ptr == NULL) {
4734 // This will either forward-to-self, or detect that someone else has
4735 // installed a forwarding pointer.
4736 return _g1h->handle_evacuation_failure_par(this, old);
4737 }
4738
4739 oop obj = oop(obj_ptr);
4740
4741 // We're going to allocate linearly, so might as well prefetch ahead.
4742 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4743
4744 oop forward_ptr = old->forward_to_atomic(obj);
4745 if (forward_ptr == NULL) {
4746 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4747
4748 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4749 // we actually allocated from and update alloc_purpose accordingly
4750 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4751 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4752
4753 if (g1p->track_object_age(alloc_purpose)) {
4754 // We could simply do obj->incr_age(). However, this causes a
4755 // performance issue. obj->incr_age() will first check whether
4756 // the object has a displaced mark by checking its mark word;
4757 // getting the mark word from the new location of the object
4758 // stalls. So, given that we already have the mark word and we
4759 // are about to install it anyway, it's better to increase the
4760 // age on the mark word, when the object does not have a
4761 // displaced mark word. We're not expecting many objects to have
4762 // a displaced marked word, so that case is not optimized
4763 // further (it could be...) and we simply call obj->incr_age().
4764
4765 if (m->has_displaced_mark_helper()) {
4766 // in this case, we have to install the mark word first,
4767 // otherwise obj looks to be forwarded (the old mark word,
4768 // which contains the forward pointer, was copied)
4769 obj->set_mark(m);
4770 obj->incr_age();
4771 } else {
4772 m = m->incr_age();
4773 obj->set_mark(m);
4774 }
4775 age_table()->add(obj, word_sz);
4776 } else {
4777 obj->set_mark(m);
4778 }
4779
4780 if (G1StringDedup::is_enabled()) {
4781 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4782 to_region->is_young(),
4783 queue_num(),
4784 obj);
4785 }
4786
4787 size_t* surv_young_words = surviving_young_words();
4788 surv_young_words[young_index] += word_sz;
4789
4790 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4791 // We keep track of the next start index in the length field of
4792 // the to-space object. The actual length can be found in the
4793 // length field of the from-space object.
4794 arrayOop(obj)->set_length(0);
4795 oop* old_p = set_partial_array_mask(old);
4796 push_on_queue(old_p);
4797 } else {
4798 // No point in using the slower heap_region_containing() method,
4799 // given that we know obj is in the heap.
4800 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4801 obj->oop_iterate_backwards(&_scanner);
4802 }
4803 } else {
4804 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4805 obj = forward_ptr;
4806 }
4807 return obj;
4808 }
4809
4810 template <class T>
4811 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4812 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4813 _scanned_klass->record_modified_oops();
4814 }
4815 }
4816
4817 template <G1Barrier barrier, bool do_mark_object>
4818 template <class T>
4819 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4820 T heap_oop = oopDesc::load_heap_oop(p);
4821
4822 if (oopDesc::is_null(heap_oop)) {
4823 return;
4824 }
4825
4826 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4827
4828 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4829
4830 if (_g1->in_cset_fast_test(obj)) {
4831 oop forwardee;
4832 if (obj->is_forwarded()) {
4833 forwardee = obj->forwardee();
4834 } else {
4835 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4836 }
4837 assert(forwardee != NULL, "forwardee should not be NULL");
4838 oopDesc::encode_store_heap_oop(p, forwardee);
4839 if (do_mark_object && forwardee != obj) {
4840 // If the object is self-forwarded we don't need to explicitly
4841 // mark it, the evacuation failure protocol will do so.
4842 mark_forwarded_object(obj, forwardee);
4843 }
4844
4845 if (barrier == G1BarrierKlass) {
4846 do_klass_barrier(p, forwardee);
4847 }
4848 } else {
4849 // The object is not in collection set. If we're a root scanning
4850 // closure during an initial mark pause (i.e. do_mark_object will
4851 // be true) then attempt to mark the object.
4852 if (do_mark_object) {
4853 mark_object(obj);
4854 }
4855 }
4856
4857 if (barrier == G1BarrierEvac) {
4858 _par_scan_state->update_rs(_from, p, _worker_id);
4859 }
4860 }
4861
4862 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4863 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4864
4865 class G1ParEvacuateFollowersClosure : public VoidClosure {
4866 protected:
4867 G1CollectedHeap* _g1h;
4868 G1ParScanThreadState* _par_scan_state;
4869 RefToScanQueueSet* _queues;
4870 ParallelTaskTerminator* _terminator;
4871
4872 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4873 RefToScanQueueSet* queues() { return _queues; }
4874 ParallelTaskTerminator* terminator() { return _terminator; }
4875
4876 public:
4877 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4878 G1ParScanThreadState* par_scan_state,
4879 RefToScanQueueSet* queues,
4880 ParallelTaskTerminator* terminator)
4881 : _g1h(g1h), _par_scan_state(par_scan_state),
4882 _queues(queues), _terminator(terminator) {}
4883
4884 void do_void();
4885
4886 private:
4887 inline bool offer_termination();
4888 };
4889
4890 bool G1ParEvacuateFollowersClosure::offer_termination() {
4891 G1ParScanThreadState* const pss = par_scan_state();
4892 pss->start_term_time();
4893 const bool res = terminator()->offer_termination();
4894 pss->end_term_time();
4895 return res;
4896 }
4897
4898 void G1ParEvacuateFollowersClosure::do_void() {
4899 StarTask stolen_task;
4900 G1ParScanThreadState* const pss = par_scan_state();
4901 pss->trim_queue();
4902
4903 do {
4904 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4905 assert(pss->verify_task(stolen_task), "sanity");
4906 if (stolen_task.is_narrow()) {
4907 pss->deal_with_reference((narrowOop*) stolen_task);
4908 } else {
4909 pss->deal_with_reference((oop*) stolen_task);
4910 }
4911
4912 // We've just processed a reference and we might have made
4913 // available new entries on the queues. So we have to make sure
4914 // we drain the queues as necessary.
4915 pss->trim_queue();
4916 }
4917 } while (!offer_termination());
4918
4919 pss->retire_alloc_buffers();
4920 }
4921
4922 class G1KlassScanClosure : public KlassClosure {
4923 G1ParCopyHelper* _closure;
4924 bool _process_only_dirty;
4925 int _count;
4926 public:
4927 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4928 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4929 void do_klass(Klass* klass) {
4930 // If the klass has not been dirtied we know that there's
4931 // no references into the young gen and we can skip it.
4932 if (!_process_only_dirty || klass->has_modified_oops()) {
4933 // Clean the klass since we're going to scavenge all the metadata.
4934 klass->clear_modified_oops();
4935
4936 // Tell the closure that this klass is the Klass to scavenge
4937 // and is the one to dirty if oops are left pointing into the young gen.
4938 _closure->set_scanned_klass(klass);
4939
4940 klass->oops_do(_closure);
4941
4942 _closure->set_scanned_klass(NULL);
4943 }
4944 _count++;
4945 }
4946 };
4947
4948 class G1ParTask : public AbstractGangTask {
4949 protected:
4950 G1CollectedHeap* _g1h;
4951 RefToScanQueueSet *_queues;
4952 ParallelTaskTerminator _terminator;
4953 uint _n_workers;
4954
4955 Mutex _stats_lock;
4956 Mutex* stats_lock() { return &_stats_lock; }
4957
4958 size_t getNCards() {
4959 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4960 / G1BlockOffsetSharedArray::N_bytes;
4961 }
4962
4963 public:
4964 G1ParTask(G1CollectedHeap* g1h,
4965 RefToScanQueueSet *task_queues)
4966 : AbstractGangTask("G1 collection"),
4967 _g1h(g1h),
4968 _queues(task_queues),
4969 _terminator(0, _queues),
4970 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4971 {}
4972
4973 RefToScanQueueSet* queues() { return _queues; }
4974
4975 RefToScanQueue *work_queue(int i) {
4976 return queues()->queue(i);
4977 }
4978
4979 ParallelTaskTerminator* terminator() { return &_terminator; }
4980
4981 virtual void set_for_termination(int active_workers) {
4982 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4983 // in the young space (_par_seq_tasks) in the G1 heap
4984 // for SequentialSubTasksDone.
4985 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4986 // both of which need setting by set_n_termination().
4987 _g1h->SharedHeap::set_n_termination(active_workers);
4988 _g1h->set_n_termination(active_workers);
4989 terminator()->reset_for_reuse(active_workers);
4990 _n_workers = active_workers;
4991 }
4992
4993 void work(uint worker_id) {
4994 if (worker_id >= _n_workers) return; // no work needed this round
4995
4996 double start_time_ms = os::elapsedTime() * 1000.0;
4997 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4998
4999 {
5000 ResourceMark rm;
5001 HandleMark hm;
5002
5003 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5004
5005 G1ParScanThreadState pss(_g1h, worker_id, rp);
5006 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5007
5008 pss.set_evac_failure_closure(&evac_failure_cl);
5009
5010 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5011 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5012
5013 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5014 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5015
5016 bool only_young = _g1h->g1_policy()->gcs_are_young();
5017 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5018 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5019
5020 OopClosure* scan_root_cl = &only_scan_root_cl;
5021 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5022
5023 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5024 // We also need to mark copied objects.
5025 scan_root_cl = &scan_mark_root_cl;
5026 scan_klasses_cl = &scan_mark_klasses_cl_s;
5027 }
5028
5029 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5030
5031 // Don't scan the scavengable methods in the code cache as part
5032 // of strong root scanning. The code roots that point into a
5033 // region in the collection set are scanned when we scan the
5034 // region's RSet.
5035 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5036
5037 pss.start_strong_roots();
5038 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5039 SharedHeap::ScanningOption(so),
5040 scan_root_cl,
5041 &push_heap_rs_cl,
5042 scan_klasses_cl,
5043 worker_id);
5044 pss.end_strong_roots();
5045
5046 {
5047 double start = os::elapsedTime();
5048 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5049 evac.do_void();
5050 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5051 double term_ms = pss.term_time()*1000.0;
5052 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5053 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5054 }
5055 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5056 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5057
5058 if (ParallelGCVerbose) {
5059 MutexLocker x(stats_lock());
5060 pss.print_termination_stats(worker_id);
5061 }
5062
5063 assert(pss.refs()->is_empty(), "should be empty");
5064
5065 // Close the inner scope so that the ResourceMark and HandleMark
5066 // destructors are executed here and are included as part of the
5067 // "GC Worker Time".
5068 }
5069
5070 double end_time_ms = os::elapsedTime() * 1000.0;
5071 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5072 }
5073 };
5074
5075 // *** Common G1 Evacuation Stuff
5076
5077 // This method is run in a GC worker.
5078
5079 void
5080 G1CollectedHeap::
5081 g1_process_strong_roots(bool is_scavenging,
5082 ScanningOption so,
5083 OopClosure* scan_non_heap_roots,
5084 OopsInHeapRegionClosure* scan_rs,
5085 G1KlassScanClosure* scan_klasses,
5086 uint worker_i) {
5087
5088 // First scan the strong roots
5089 double ext_roots_start = os::elapsedTime();
5090 double closure_app_time_sec = 0.0;
5091
5092 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5093
5094 process_strong_roots(false, // no scoping; this is parallel code
5095 so,
5096 &buf_scan_non_heap_roots,
5097 scan_klasses
5098 );
5099
5100 // Now the CM ref_processor roots.
5101 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5102 // We need to treat the discovered reference lists of the
5103 // concurrent mark ref processor as roots and keep entries
5104 // (which are added by the marking threads) on them live
5105 // until they can be processed at the end of marking.
5106 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5107 }
5108
5109 // Finish up any enqueued closure apps (attributed as object copy time).
5110 buf_scan_non_heap_roots.done();
5111
5112 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5113
5114 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5115
5116 double ext_root_time_ms =
5117 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5118
5119 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5120
5121 // During conc marking we have to filter the per-thread SATB buffers
5122 // to make sure we remove any oops into the CSet (which will show up
5123 // as implicitly live).
5124 double satb_filtering_ms = 0.0;
5125 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5126 if (mark_in_progress()) {
5127 double satb_filter_start = os::elapsedTime();
5128
5129 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5130
5131 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5132 }
5133 }
5134 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5135
5136 // If this is an initial mark pause, and we're not scanning
5137 // the entire code cache, we need to mark the oops in the
5138 // strong code root lists for the regions that are not in
5139 // the collection set.
5140 // Note all threads participate in this set of root tasks.
5141 double mark_strong_code_roots_ms = 0.0;
5142 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5143 double mark_strong_roots_start = os::elapsedTime();
5144 mark_strong_code_roots(worker_i);
5145 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5146 }
5147 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5148
5149 // Now scan the complement of the collection set.
5150 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5151 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5152
5153 _process_strong_tasks->all_tasks_completed();
5154 }
5155
5156 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5157 private:
5158 BoolObjectClosure* _is_alive;
5159 int _initial_string_table_size;
5160 int _initial_symbol_table_size;
5161
5162 bool _process_strings;
5163 int _strings_processed;
5164 int _strings_removed;
5165
5166 bool _process_symbols;
5167 int _symbols_processed;
5168 int _symbols_removed;
5169
5170 bool _do_in_parallel;
5171 public:
5172 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5173 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5174 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5175 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5176 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5177
5178 _initial_string_table_size = StringTable::the_table()->table_size();
5179 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5180 if (process_strings) {
5181 StringTable::clear_parallel_claimed_index();
5182 }
5183 if (process_symbols) {
5184 SymbolTable::clear_parallel_claimed_index();
5185 }
5186 }
5187
5188 ~G1StringSymbolTableUnlinkTask() {
5189 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5190 err_msg("claim value %d after unlink less than initial string table size %d",
5191 StringTable::parallel_claimed_index(), _initial_string_table_size));
5192 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5193 err_msg("claim value %d after unlink less than initial symbol table size %d",
5194 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5195 }
5196
5197 void work(uint worker_id) {
5198 if (_do_in_parallel) {
5199 int strings_processed = 0;
5200 int strings_removed = 0;
5201 int symbols_processed = 0;
5202 int symbols_removed = 0;
5203 if (_process_strings) {
5204 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5205 Atomic::add(strings_processed, &_strings_processed);
5206 Atomic::add(strings_removed, &_strings_removed);
5207 }
5208 if (_process_symbols) {
5209 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5210 Atomic::add(symbols_processed, &_symbols_processed);
5211 Atomic::add(symbols_removed, &_symbols_removed);
5212 }
5213 } else {
5214 if (_process_strings) {
5215 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5216 }
5217 if (_process_symbols) {
5218 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5219 }
5220 }
5221 }
5222
5223 size_t strings_processed() const { return (size_t)_strings_processed; }
5224 size_t strings_removed() const { return (size_t)_strings_removed; }
5225
5226 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5227 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5228 };
5229
5230 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5231 bool process_strings, bool process_symbols) {
5232 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5233 _g1h->workers()->active_workers() : 1);
5234
5235 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5236 if (G1CollectedHeap::use_parallel_gc_threads()) {
5237 set_par_threads(n_workers);
5238 workers()->run_task(&g1_unlink_task);
5239 set_par_threads(0);
5240 } else {
5241 g1_unlink_task.work(0);
5242 }
5243 if (G1TraceStringSymbolTableScrubbing) {
5244 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5245 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5246 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5247 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5248 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5249 }
5250
5251 if (G1StringDedup::is_enabled()) {
5252 G1StringDedup::unlink(is_alive);
5253 }
5254 }
5255
5256 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
5257 public:
5258 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
5259 *card_ptr = CardTableModRefBS::dirty_card_val();
5260 return true;
5261 }
5262 };
5263
5264 void G1CollectedHeap::redirty_logged_cards() {
5265 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5266 double redirty_logged_cards_start = os::elapsedTime();
5267
5268 RedirtyLoggedCardTableEntryFastClosure redirty;
5269 dirty_card_queue_set().set_closure(&redirty);
5270 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5271
5272 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5273 dcq.merge_bufferlists(&dirty_card_queue_set());
5274 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5275
5276 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5277 }
5278
5279 // Weak Reference Processing support
5280
5281 // An always "is_alive" closure that is used to preserve referents.
5282 // If the object is non-null then it's alive. Used in the preservation
5283 // of referent objects that are pointed to by reference objects
5284 // discovered by the CM ref processor.
5285 class G1AlwaysAliveClosure: public BoolObjectClosure {
5286 G1CollectedHeap* _g1;
5287 public:
5288 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5289 bool do_object_b(oop p) {
5290 if (p != NULL) {
5291 return true;
5292 }
5293 return false;
5294 }
5295 };
5296
5297 bool G1STWIsAliveClosure::do_object_b(oop p) {
5298 // An object is reachable if it is outside the collection set,
5299 // or is inside and copied.
5300 return !_g1->obj_in_cs(p) || p->is_forwarded();
5301 }
5302
5303 // Non Copying Keep Alive closure
5304 class G1KeepAliveClosure: public OopClosure {
5305 G1CollectedHeap* _g1;
5306 public:
5307 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5308 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5309 void do_oop( oop* p) {
5310 oop obj = *p;
5311
5312 if (_g1->obj_in_cs(obj)) {
5313 assert( obj->is_forwarded(), "invariant" );
5314 *p = obj->forwardee();
5315 }
5316 }
5317 };
5318
5319 // Copying Keep Alive closure - can be called from both
5320 // serial and parallel code as long as different worker
5321 // threads utilize different G1ParScanThreadState instances
5322 // and different queues.
5323
5324 class G1CopyingKeepAliveClosure: public OopClosure {
5325 G1CollectedHeap* _g1h;
5326 OopClosure* _copy_non_heap_obj_cl;
5327 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5328 G1ParScanThreadState* _par_scan_state;
5329
5330 public:
5331 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5332 OopClosure* non_heap_obj_cl,
5333 OopsInHeapRegionClosure* metadata_obj_cl,
5334 G1ParScanThreadState* pss):
5335 _g1h(g1h),
5336 _copy_non_heap_obj_cl(non_heap_obj_cl),
5337 _copy_metadata_obj_cl(metadata_obj_cl),
5338 _par_scan_state(pss)
5339 {}
5340
5341 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5342 virtual void do_oop( oop* p) { do_oop_work(p); }
5343
5344 template <class T> void do_oop_work(T* p) {
5345 oop obj = oopDesc::load_decode_heap_oop(p);
5346
5347 if (_g1h->obj_in_cs(obj)) {
5348 // If the referent object has been forwarded (either copied
5349 // to a new location or to itself in the event of an
5350 // evacuation failure) then we need to update the reference
5351 // field and, if both reference and referent are in the G1
5352 // heap, update the RSet for the referent.
5353 //
5354 // If the referent has not been forwarded then we have to keep
5355 // it alive by policy. Therefore we have copy the referent.
5356 //
5357 // If the reference field is in the G1 heap then we can push
5358 // on the PSS queue. When the queue is drained (after each
5359 // phase of reference processing) the object and it's followers
5360 // will be copied, the reference field set to point to the
5361 // new location, and the RSet updated. Otherwise we need to
5362 // use the the non-heap or metadata closures directly to copy
5363 // the referent object and update the pointer, while avoiding
5364 // updating the RSet.
5365
5366 if (_g1h->is_in_g1_reserved(p)) {
5367 _par_scan_state->push_on_queue(p);
5368 } else {
5369 assert(!ClassLoaderDataGraph::contains((address)p),
5370 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5371 PTR_FORMAT, p));
5372 _copy_non_heap_obj_cl->do_oop(p);
5373 }
5374 }
5375 }
5376 };
5377
5378 // Serial drain queue closure. Called as the 'complete_gc'
5379 // closure for each discovered list in some of the
5380 // reference processing phases.
5381
5382 class G1STWDrainQueueClosure: public VoidClosure {
5383 protected:
5384 G1CollectedHeap* _g1h;
5385 G1ParScanThreadState* _par_scan_state;
5386
5387 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5388
5389 public:
5390 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5391 _g1h(g1h),
5392 _par_scan_state(pss)
5393 { }
5394
5395 void do_void() {
5396 G1ParScanThreadState* const pss = par_scan_state();
5397 pss->trim_queue();
5398 }
5399 };
5400
5401 // Parallel Reference Processing closures
5402
5403 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5404 // processing during G1 evacuation pauses.
5405
5406 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5407 private:
5408 G1CollectedHeap* _g1h;
5409 RefToScanQueueSet* _queues;
5410 FlexibleWorkGang* _workers;
5411 int _active_workers;
5412
5413 public:
5414 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5415 FlexibleWorkGang* workers,
5416 RefToScanQueueSet *task_queues,
5417 int n_workers) :
5418 _g1h(g1h),
5419 _queues(task_queues),
5420 _workers(workers),
5421 _active_workers(n_workers)
5422 {
5423 assert(n_workers > 0, "shouldn't call this otherwise");
5424 }
5425
5426 // Executes the given task using concurrent marking worker threads.
5427 virtual void execute(ProcessTask& task);
5428 virtual void execute(EnqueueTask& task);
5429 };
5430
5431 // Gang task for possibly parallel reference processing
5432
5433 class G1STWRefProcTaskProxy: public AbstractGangTask {
5434 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5435 ProcessTask& _proc_task;
5436 G1CollectedHeap* _g1h;
5437 RefToScanQueueSet *_task_queues;
5438 ParallelTaskTerminator* _terminator;
5439
5440 public:
5441 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5442 G1CollectedHeap* g1h,
5443 RefToScanQueueSet *task_queues,
5444 ParallelTaskTerminator* terminator) :
5445 AbstractGangTask("Process reference objects in parallel"),
5446 _proc_task(proc_task),
5447 _g1h(g1h),
5448 _task_queues(task_queues),
5449 _terminator(terminator)
5450 {}
5451
5452 virtual void work(uint worker_id) {
5453 // The reference processing task executed by a single worker.
5454 ResourceMark rm;
5455 HandleMark hm;
5456
5457 G1STWIsAliveClosure is_alive(_g1h);
5458
5459 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5460 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5461
5462 pss.set_evac_failure_closure(&evac_failure_cl);
5463
5464 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5465 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5466
5467 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5468 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5469
5470 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5471 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5472
5473 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5474 // We also need to mark copied objects.
5475 copy_non_heap_cl = ©_mark_non_heap_cl;
5476 copy_metadata_cl = ©_mark_metadata_cl;
5477 }
5478
5479 // Keep alive closure.
5480 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5481
5482 // Complete GC closure
5483 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5484
5485 // Call the reference processing task's work routine.
5486 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5487
5488 // Note we cannot assert that the refs array is empty here as not all
5489 // of the processing tasks (specifically phase2 - pp2_work) execute
5490 // the complete_gc closure (which ordinarily would drain the queue) so
5491 // the queue may not be empty.
5492 }
5493 };
5494
5495 // Driver routine for parallel reference processing.
5496 // Creates an instance of the ref processing gang
5497 // task and has the worker threads execute it.
5498 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5499 assert(_workers != NULL, "Need parallel worker threads.");
5500
5501 ParallelTaskTerminator terminator(_active_workers, _queues);
5502 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5503
5504 _g1h->set_par_threads(_active_workers);
5505 _workers->run_task(&proc_task_proxy);
5506 _g1h->set_par_threads(0);
5507 }
5508
5509 // Gang task for parallel reference enqueueing.
5510
5511 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5512 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5513 EnqueueTask& _enq_task;
5514
5515 public:
5516 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5517 AbstractGangTask("Enqueue reference objects in parallel"),
5518 _enq_task(enq_task)
5519 { }
5520
5521 virtual void work(uint worker_id) {
5522 _enq_task.work(worker_id);
5523 }
5524 };
5525
5526 // Driver routine for parallel reference enqueueing.
5527 // Creates an instance of the ref enqueueing gang
5528 // task and has the worker threads execute it.
5529
5530 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5531 assert(_workers != NULL, "Need parallel worker threads.");
5532
5533 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5534
5535 _g1h->set_par_threads(_active_workers);
5536 _workers->run_task(&enq_task_proxy);
5537 _g1h->set_par_threads(0);
5538 }
5539
5540 // End of weak reference support closures
5541
5542 // Abstract task used to preserve (i.e. copy) any referent objects
5543 // that are in the collection set and are pointed to by reference
5544 // objects discovered by the CM ref processor.
5545
5546 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5547 protected:
5548 G1CollectedHeap* _g1h;
5549 RefToScanQueueSet *_queues;
5550 ParallelTaskTerminator _terminator;
5551 uint _n_workers;
5552
5553 public:
5554 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5555 AbstractGangTask("ParPreserveCMReferents"),
5556 _g1h(g1h),
5557 _queues(task_queues),
5558 _terminator(workers, _queues),
5559 _n_workers(workers)
5560 { }
5561
5562 void work(uint worker_id) {
5563 ResourceMark rm;
5564 HandleMark hm;
5565
5566 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5567 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5568
5569 pss.set_evac_failure_closure(&evac_failure_cl);
5570
5571 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5572
5573
5574 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5575 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5576
5577 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5578 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5579
5580 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5581 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5582
5583 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5584 // We also need to mark copied objects.
5585 copy_non_heap_cl = ©_mark_non_heap_cl;
5586 copy_metadata_cl = ©_mark_metadata_cl;
5587 }
5588
5589 // Is alive closure
5590 G1AlwaysAliveClosure always_alive(_g1h);
5591
5592 // Copying keep alive closure. Applied to referent objects that need
5593 // to be copied.
5594 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5595
5596 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5597
5598 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5599 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5600
5601 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5602 // So this must be true - but assert just in case someone decides to
5603 // change the worker ids.
5604 assert(0 <= worker_id && worker_id < limit, "sanity");
5605 assert(!rp->discovery_is_atomic(), "check this code");
5606
5607 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5608 for (uint idx = worker_id; idx < limit; idx += stride) {
5609 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5610
5611 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5612 while (iter.has_next()) {
5613 // Since discovery is not atomic for the CM ref processor, we
5614 // can see some null referent objects.
5615 iter.load_ptrs(DEBUG_ONLY(true));
5616 oop ref = iter.obj();
5617
5618 // This will filter nulls.
5619 if (iter.is_referent_alive()) {
5620 iter.make_referent_alive();
5621 }
5622 iter.move_to_next();
5623 }
5624 }
5625
5626 // Drain the queue - which may cause stealing
5627 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5628 drain_queue.do_void();
5629 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5630 assert(pss.refs()->is_empty(), "should be");
5631 }
5632 };
5633
5634 // Weak Reference processing during an evacuation pause (part 1).
5635 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5636 double ref_proc_start = os::elapsedTime();
5637
5638 ReferenceProcessor* rp = _ref_processor_stw;
5639 assert(rp->discovery_enabled(), "should have been enabled");
5640
5641 // Any reference objects, in the collection set, that were 'discovered'
5642 // by the CM ref processor should have already been copied (either by
5643 // applying the external root copy closure to the discovered lists, or
5644 // by following an RSet entry).
5645 //
5646 // But some of the referents, that are in the collection set, that these
5647 // reference objects point to may not have been copied: the STW ref
5648 // processor would have seen that the reference object had already
5649 // been 'discovered' and would have skipped discovering the reference,
5650 // but would not have treated the reference object as a regular oop.
5651 // As a result the copy closure would not have been applied to the
5652 // referent object.
5653 //
5654 // We need to explicitly copy these referent objects - the references
5655 // will be processed at the end of remarking.
5656 //
5657 // We also need to do this copying before we process the reference
5658 // objects discovered by the STW ref processor in case one of these
5659 // referents points to another object which is also referenced by an
5660 // object discovered by the STW ref processor.
5661
5662 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5663 no_of_gc_workers == workers()->active_workers(),
5664 "Need to reset active GC workers");
5665
5666 set_par_threads(no_of_gc_workers);
5667 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5668 no_of_gc_workers,
5669 _task_queues);
5670
5671 if (G1CollectedHeap::use_parallel_gc_threads()) {
5672 workers()->run_task(&keep_cm_referents);
5673 } else {
5674 keep_cm_referents.work(0);
5675 }
5676
5677 set_par_threads(0);
5678
5679 // Closure to test whether a referent is alive.
5680 G1STWIsAliveClosure is_alive(this);
5681
5682 // Even when parallel reference processing is enabled, the processing
5683 // of JNI refs is serial and performed serially by the current thread
5684 // rather than by a worker. The following PSS will be used for processing
5685 // JNI refs.
5686
5687 // Use only a single queue for this PSS.
5688 G1ParScanThreadState pss(this, 0, NULL);
5689
5690 // We do not embed a reference processor in the copying/scanning
5691 // closures while we're actually processing the discovered
5692 // reference objects.
5693 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5694
5695 pss.set_evac_failure_closure(&evac_failure_cl);
5696
5697 assert(pss.refs()->is_empty(), "pre-condition");
5698
5699 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5700 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5701
5702 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5703 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5704
5705 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5706 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5707
5708 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5709 // We also need to mark copied objects.
5710 copy_non_heap_cl = ©_mark_non_heap_cl;
5711 copy_metadata_cl = ©_mark_metadata_cl;
5712 }
5713
5714 // Keep alive closure.
5715 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5716
5717 // Serial Complete GC closure
5718 G1STWDrainQueueClosure drain_queue(this, &pss);
5719
5720 // Setup the soft refs policy...
5721 rp->setup_policy(false);
5722
5723 ReferenceProcessorStats stats;
5724 if (!rp->processing_is_mt()) {
5725 // Serial reference processing...
5726 stats = rp->process_discovered_references(&is_alive,
5727 &keep_alive,
5728 &drain_queue,
5729 NULL,
5730 _gc_timer_stw);
5731 } else {
5732 // Parallel reference processing
5733 assert(rp->num_q() == no_of_gc_workers, "sanity");
5734 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5735
5736 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5737 stats = rp->process_discovered_references(&is_alive,
5738 &keep_alive,
5739 &drain_queue,
5740 &par_task_executor,
5741 _gc_timer_stw);
5742 }
5743
5744 _gc_tracer_stw->report_gc_reference_stats(stats);
5745 // We have completed copying any necessary live referent objects
5746 // (that were not copied during the actual pause) so we can
5747 // retire any active alloc buffers
5748 pss.retire_alloc_buffers();
5749 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5750
5751 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5752 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5753 }
5754
5755 // Weak Reference processing during an evacuation pause (part 2).
5756 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5757 double ref_enq_start = os::elapsedTime();
5758
5759 ReferenceProcessor* rp = _ref_processor_stw;
5760 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5761
5762 // Now enqueue any remaining on the discovered lists on to
5763 // the pending list.
5764 if (!rp->processing_is_mt()) {
5765 // Serial reference processing...
5766 rp->enqueue_discovered_references();
5767 } else {
5768 // Parallel reference enqueueing
5769
5770 assert(no_of_gc_workers == workers()->active_workers(),
5771 "Need to reset active workers");
5772 assert(rp->num_q() == no_of_gc_workers, "sanity");
5773 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5774
5775 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5776 rp->enqueue_discovered_references(&par_task_executor);
5777 }
5778
5779 rp->verify_no_references_recorded();
5780 assert(!rp->discovery_enabled(), "should have been disabled");
5781
5782 // FIXME
5783 // CM's reference processing also cleans up the string and symbol tables.
5784 // Should we do that here also? We could, but it is a serial operation
5785 // and could significantly increase the pause time.
5786
5787 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5788 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5789 }
5790
5791 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5792 _expand_heap_after_alloc_failure = true;
5793 _evacuation_failed = false;
5794
5795 // Should G1EvacuationFailureALot be in effect for this GC?
5796 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5797
5798 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5799
5800 // Disable the hot card cache.
5801 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5802 hot_card_cache->reset_hot_cache_claimed_index();
5803 hot_card_cache->set_use_cache(false);
5804
5805 uint n_workers;
5806 if (G1CollectedHeap::use_parallel_gc_threads()) {
5807 n_workers =
5808 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5809 workers()->active_workers(),
5810 Threads::number_of_non_daemon_threads());
5811 assert(UseDynamicNumberOfGCThreads ||
5812 n_workers == workers()->total_workers(),
5813 "If not dynamic should be using all the workers");
5814 workers()->set_active_workers(n_workers);
5815 set_par_threads(n_workers);
5816 } else {
5817 assert(n_par_threads() == 0,
5818 "Should be the original non-parallel value");
5819 n_workers = 1;
5820 }
5821
5822 G1ParTask g1_par_task(this, _task_queues);
5823
5824 init_for_evac_failure(NULL);
5825
5826 rem_set()->prepare_for_younger_refs_iterate(true);
5827
5828 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5829 double start_par_time_sec = os::elapsedTime();
5830 double end_par_time_sec;
5831
5832 {
5833 StrongRootsScope srs(this);
5834
5835 if (G1CollectedHeap::use_parallel_gc_threads()) {
5836 // The individual threads will set their evac-failure closures.
5837 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5838 // These tasks use ShareHeap::_process_strong_tasks
5839 assert(UseDynamicNumberOfGCThreads ||
5840 workers()->active_workers() == workers()->total_workers(),
5841 "If not dynamic should be using all the workers");
5842 workers()->run_task(&g1_par_task);
5843 } else {
5844 g1_par_task.set_for_termination(n_workers);
5845 g1_par_task.work(0);
5846 }
5847 end_par_time_sec = os::elapsedTime();
5848
5849 // Closing the inner scope will execute the destructor
5850 // for the StrongRootsScope object. We record the current
5851 // elapsed time before closing the scope so that time
5852 // taken for the SRS destructor is NOT included in the
5853 // reported parallel time.
5854 }
5855
5856 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5857 g1_policy()->phase_times()->record_par_time(par_time_ms);
5858
5859 double code_root_fixup_time_ms =
5860 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5861 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5862
5863 set_par_threads(0);
5864
5865 // Process any discovered reference objects - we have
5866 // to do this _before_ we retire the GC alloc regions
5867 // as we may have to copy some 'reachable' referent
5868 // objects (and their reachable sub-graphs) that were
5869 // not copied during the pause.
5870 process_discovered_references(n_workers);
5871
5872 // Weak root processing.
5873 {
5874 G1STWIsAliveClosure is_alive(this);
5875 G1KeepAliveClosure keep_alive(this);
5876 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5877 if (G1StringDedup::is_enabled()) {
5878 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5879 }
5880 }
5881
5882 release_gc_alloc_regions(n_workers, evacuation_info);
5883 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5884
5885 // Reset and re-enable the hot card cache.
5886 // Note the counts for the cards in the regions in the
5887 // collection set are reset when the collection set is freed.
5888 hot_card_cache->reset_hot_cache();
5889 hot_card_cache->set_use_cache(true);
5890
5891 // Migrate the strong code roots attached to each region in
5892 // the collection set. Ideally we would like to do this
5893 // after we have finished the scanning/evacuation of the
5894 // strong code roots for a particular heap region.
5895 migrate_strong_code_roots();
5896
5897 purge_code_root_memory();
5898
5899 if (g1_policy()->during_initial_mark_pause()) {
5900 // Reset the claim values set during marking the strong code roots
5901 reset_heap_region_claim_values();
5902 }
5903
5904 finalize_for_evac_failure();
5905
5906 if (evacuation_failed()) {
5907 remove_self_forwarding_pointers();
5908
5909 // Reset the G1EvacuationFailureALot counters and flags
5910 // Note: the values are reset only when an actual
5911 // evacuation failure occurs.
5912 NOT_PRODUCT(reset_evacuation_should_fail();)
5913 }
5914
5915 // Enqueue any remaining references remaining on the STW
5916 // reference processor's discovered lists. We need to do
5917 // this after the card table is cleaned (and verified) as
5918 // the act of enqueueing entries on to the pending list
5919 // will log these updates (and dirty their associated
5920 // cards). We need these updates logged to update any
5921 // RSets.
5922 enqueue_discovered_references(n_workers);
5923
5924 if (G1DeferredRSUpdate) {
5925 redirty_logged_cards();
5926 }
5927 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5928 }
5929
5930 void G1CollectedHeap::free_region(HeapRegion* hr,
5931 FreeRegionList* free_list,
5932 bool par,
5933 bool locked) {
5934 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5935 assert(!hr->is_empty(), "the region should not be empty");
5936 assert(free_list != NULL, "pre-condition");
5937
5938 // Clear the card counts for this region.
5939 // Note: we only need to do this if the region is not young
5940 // (since we don't refine cards in young regions).
5941 if (!hr->is_young()) {
5942 _cg1r->hot_card_cache()->reset_card_counts(hr);
5943 }
5944 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5945 free_list->add_ordered(hr);
5946 }
5947
5948 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5949 FreeRegionList* free_list,
5950 bool par) {
5951 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5952 assert(free_list != NULL, "pre-condition");
5953
5954 size_t hr_capacity = hr->capacity();
5955 // We need to read this before we make the region non-humongous,
5956 // otherwise the information will be gone.
5957 uint last_index = hr->last_hc_index();
5958 hr->set_notHumongous();
5959 free_region(hr, free_list, par);
5960
5961 uint i = hr->hrs_index() + 1;
5962 while (i < last_index) {
5963 HeapRegion* curr_hr = region_at(i);
5964 assert(curr_hr->continuesHumongous(), "invariant");
5965 curr_hr->set_notHumongous();
5966 free_region(curr_hr, free_list, par);
5967 i += 1;
5968 }
5969 }
5970
5971 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5972 const HeapRegionSetCount& humongous_regions_removed) {
5973 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5974 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5975 _old_set.bulk_remove(old_regions_removed);
5976 _humongous_set.bulk_remove(humongous_regions_removed);
5977 }
5978
5979 }
5980
5981 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5982 assert(list != NULL, "list can't be null");
5983 if (!list->is_empty()) {
5984 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5985 _free_list.add_ordered(list);
5986 }
5987 }
5988
5989 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5990 assert(_summary_bytes_used >= bytes,
5991 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
5992 _summary_bytes_used, bytes));
5993 _summary_bytes_used -= bytes;
5994 }
5995
5996 class G1ParCleanupCTTask : public AbstractGangTask {
5997 G1SATBCardTableModRefBS* _ct_bs;
5998 G1CollectedHeap* _g1h;
5999 HeapRegion* volatile _su_head;
6000 public:
6001 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6002 G1CollectedHeap* g1h) :
6003 AbstractGangTask("G1 Par Cleanup CT Task"),
6004 _ct_bs(ct_bs), _g1h(g1h) { }
6005
6006 void work(uint worker_id) {
6007 HeapRegion* r;
6008 while (r = _g1h->pop_dirty_cards_region()) {
6009 clear_cards(r);
6010 }
6011 }
6012
6013 void clear_cards(HeapRegion* r) {
6014 // Cards of the survivors should have already been dirtied.
6015 if (!r->is_survivor()) {
6016 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6017 }
6018 }
6019 };
6020
6021 #ifndef PRODUCT
6022 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6023 G1CollectedHeap* _g1h;
6024 G1SATBCardTableModRefBS* _ct_bs;
6025 public:
6026 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6027 : _g1h(g1h), _ct_bs(ct_bs) { }
6028 virtual bool doHeapRegion(HeapRegion* r) {
6029 if (r->is_survivor()) {
6030 _g1h->verify_dirty_region(r);
6031 } else {
6032 _g1h->verify_not_dirty_region(r);
6033 }
6034 return false;
6035 }
6036 };
6037
6038 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6039 // All of the region should be clean.
6040 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6041 MemRegion mr(hr->bottom(), hr->end());
6042 ct_bs->verify_not_dirty_region(mr);
6043 }
6044
6045 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6046 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6047 // dirty allocated blocks as they allocate them. The thread that
6048 // retires each region and replaces it with a new one will do a
6049 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6050 // not dirty that area (one less thing to have to do while holding
6051 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6052 // is dirty.
6053 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6054 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6055 if (hr->is_young()) {
6056 ct_bs->verify_g1_young_region(mr);
6057 } else {
6058 ct_bs->verify_dirty_region(mr);
6059 }
6060 }
6061
6062 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6063 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6064 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6065 verify_dirty_region(hr);
6066 }
6067 }
6068
6069 void G1CollectedHeap::verify_dirty_young_regions() {
6070 verify_dirty_young_list(_young_list->first_region());
6071 }
6072 #endif
6073
6074 void G1CollectedHeap::cleanUpCardTable() {
6075 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6076 double start = os::elapsedTime();
6077
6078 {
6079 // Iterate over the dirty cards region list.
6080 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6081
6082 if (G1CollectedHeap::use_parallel_gc_threads()) {
6083 set_par_threads();
6084 workers()->run_task(&cleanup_task);
6085 set_par_threads(0);
6086 } else {
6087 while (_dirty_cards_region_list) {
6088 HeapRegion* r = _dirty_cards_region_list;
6089 cleanup_task.clear_cards(r);
6090 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6091 if (_dirty_cards_region_list == r) {
6092 // The last region.
6093 _dirty_cards_region_list = NULL;
6094 }
6095 r->set_next_dirty_cards_region(NULL);
6096 }
6097 }
6098 #ifndef PRODUCT
6099 if (G1VerifyCTCleanup || VerifyAfterGC) {
6100 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6101 heap_region_iterate(&cleanup_verifier);
6102 }
6103 #endif
6104 }
6105
6106 double elapsed = os::elapsedTime() - start;
6107 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6108 }
6109
6110 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6111 size_t pre_used = 0;
6112 FreeRegionList local_free_list("Local List for CSet Freeing");
6113
6114 double young_time_ms = 0.0;
6115 double non_young_time_ms = 0.0;
6116
6117 // Since the collection set is a superset of the the young list,
6118 // all we need to do to clear the young list is clear its
6119 // head and length, and unlink any young regions in the code below
6120 _young_list->clear();
6121
6122 G1CollectorPolicy* policy = g1_policy();
6123
6124 double start_sec = os::elapsedTime();
6125 bool non_young = true;
6126
6127 HeapRegion* cur = cs_head;
6128 int age_bound = -1;
6129 size_t rs_lengths = 0;
6130
6131 while (cur != NULL) {
6132 assert(!is_on_master_free_list(cur), "sanity");
6133 if (non_young) {
6134 if (cur->is_young()) {
6135 double end_sec = os::elapsedTime();
6136 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6137 non_young_time_ms += elapsed_ms;
6138
6139 start_sec = os::elapsedTime();
6140 non_young = false;
6141 }
6142 } else {
6143 if (!cur->is_young()) {
6144 double end_sec = os::elapsedTime();
6145 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6146 young_time_ms += elapsed_ms;
6147
6148 start_sec = os::elapsedTime();
6149 non_young = true;
6150 }
6151 }
6152
6153 rs_lengths += cur->rem_set()->occupied_locked();
6154
6155 HeapRegion* next = cur->next_in_collection_set();
6156 assert(cur->in_collection_set(), "bad CS");
6157 cur->set_next_in_collection_set(NULL);
6158 cur->set_in_collection_set(false);
6159
6160 if (cur->is_young()) {
6161 int index = cur->young_index_in_cset();
6162 assert(index != -1, "invariant");
6163 assert((uint) index < policy->young_cset_region_length(), "invariant");
6164 size_t words_survived = _surviving_young_words[index];
6165 cur->record_surv_words_in_group(words_survived);
6166
6167 // At this point the we have 'popped' cur from the collection set
6168 // (linked via next_in_collection_set()) but it is still in the
6169 // young list (linked via next_young_region()). Clear the
6170 // _next_young_region field.
6171 cur->set_next_young_region(NULL);
6172 } else {
6173 int index = cur->young_index_in_cset();
6174 assert(index == -1, "invariant");
6175 }
6176
6177 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6178 (!cur->is_young() && cur->young_index_in_cset() == -1),
6179 "invariant" );
6180
6181 if (!cur->evacuation_failed()) {
6182 MemRegion used_mr = cur->used_region();
6183
6184 // And the region is empty.
6185 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6186 pre_used += cur->used();
6187 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6188 } else {
6189 cur->uninstall_surv_rate_group();
6190 if (cur->is_young()) {
6191 cur->set_young_index_in_cset(-1);
6192 }
6193 cur->set_not_young();
6194 cur->set_evacuation_failed(false);
6195 // The region is now considered to be old.
6196 _old_set.add(cur);
6197 evacuation_info.increment_collectionset_used_after(cur->used());
6198 }
6199 cur = next;
6200 }
6201
6202 evacuation_info.set_regions_freed(local_free_list.length());
6203 policy->record_max_rs_lengths(rs_lengths);
6204 policy->cset_regions_freed();
6205
6206 double end_sec = os::elapsedTime();
6207 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6208
6209 if (non_young) {
6210 non_young_time_ms += elapsed_ms;
6211 } else {
6212 young_time_ms += elapsed_ms;
6213 }
6214
6215 prepend_to_freelist(&local_free_list);
6216 decrement_summary_bytes(pre_used);
6217 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6218 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6219 }
6220
6221 // This routine is similar to the above but does not record
6222 // any policy statistics or update free lists; we are abandoning
6223 // the current incremental collection set in preparation of a
6224 // full collection. After the full GC we will start to build up
6225 // the incremental collection set again.
6226 // This is only called when we're doing a full collection
6227 // and is immediately followed by the tearing down of the young list.
6228
6229 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6230 HeapRegion* cur = cs_head;
6231
6232 while (cur != NULL) {
6233 HeapRegion* next = cur->next_in_collection_set();
6234 assert(cur->in_collection_set(), "bad CS");
6235 cur->set_next_in_collection_set(NULL);
6236 cur->set_in_collection_set(false);
6237 cur->set_young_index_in_cset(-1);
6238 cur = next;
6239 }
6240 }
6241
6242 void G1CollectedHeap::set_free_regions_coming() {
6243 if (G1ConcRegionFreeingVerbose) {
6244 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6245 "setting free regions coming");
6246 }
6247
6248 assert(!free_regions_coming(), "pre-condition");
6249 _free_regions_coming = true;
6250 }
6251
6252 void G1CollectedHeap::reset_free_regions_coming() {
6253 assert(free_regions_coming(), "pre-condition");
6254
6255 {
6256 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6257 _free_regions_coming = false;
6258 SecondaryFreeList_lock->notify_all();
6259 }
6260
6261 if (G1ConcRegionFreeingVerbose) {
6262 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6263 "reset free regions coming");
6264 }
6265 }
6266
6267 void G1CollectedHeap::wait_while_free_regions_coming() {
6268 // Most of the time we won't have to wait, so let's do a quick test
6269 // first before we take the lock.
6270 if (!free_regions_coming()) {
6271 return;
6272 }
6273
6274 if (G1ConcRegionFreeingVerbose) {
6275 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6276 "waiting for free regions");
6277 }
6278
6279 {
6280 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6281 while (free_regions_coming()) {
6282 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6283 }
6284 }
6285
6286 if (G1ConcRegionFreeingVerbose) {
6287 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6288 "done waiting for free regions");
6289 }
6290 }
6291
6292 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6293 assert(heap_lock_held_for_gc(),
6294 "the heap lock should already be held by or for this thread");
6295 _young_list->push_region(hr);
6296 }
6297
6298 class NoYoungRegionsClosure: public HeapRegionClosure {
6299 private:
6300 bool _success;
6301 public:
6302 NoYoungRegionsClosure() : _success(true) { }
6303 bool doHeapRegion(HeapRegion* r) {
6304 if (r->is_young()) {
6305 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6306 r->bottom(), r->end());
6307 _success = false;
6308 }
6309 return false;
6310 }
6311 bool success() { return _success; }
6312 };
6313
6314 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6315 bool ret = _young_list->check_list_empty(check_sample);
6316
6317 if (check_heap) {
6318 NoYoungRegionsClosure closure;
6319 heap_region_iterate(&closure);
6320 ret = ret && closure.success();
6321 }
6322
6323 return ret;
6324 }
6325
6326 class TearDownRegionSetsClosure : public HeapRegionClosure {
6327 private:
6328 HeapRegionSet *_old_set;
6329
6330 public:
6331 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6332
6333 bool doHeapRegion(HeapRegion* r) {
6334 if (r->is_empty()) {
6335 // We ignore empty regions, we'll empty the free list afterwards
6336 } else if (r->is_young()) {
6337 // We ignore young regions, we'll empty the young list afterwards
6338 } else if (r->isHumongous()) {
6339 // We ignore humongous regions, we're not tearing down the
6340 // humongous region set
6341 } else {
6342 // The rest should be old
6343 _old_set->remove(r);
6344 }
6345 return false;
6346 }
6347
6348 ~TearDownRegionSetsClosure() {
6349 assert(_old_set->is_empty(), "post-condition");
6350 }
6351 };
6352
6353 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6354 assert_at_safepoint(true /* should_be_vm_thread */);
6355
6356 if (!free_list_only) {
6357 TearDownRegionSetsClosure cl(&_old_set);
6358 heap_region_iterate(&cl);
6359
6360 // Note that emptying the _young_list is postponed and instead done as
6361 // the first step when rebuilding the regions sets again. The reason for
6362 // this is that during a full GC string deduplication needs to know if
6363 // a collected region was young or old when the full GC was initiated.
6364 }
6365 _free_list.remove_all();
6366 }
6367
6368 class RebuildRegionSetsClosure : public HeapRegionClosure {
6369 private:
6370 bool _free_list_only;
6371 HeapRegionSet* _old_set;
6372 FreeRegionList* _free_list;
6373 size_t _total_used;
6374
6375 public:
6376 RebuildRegionSetsClosure(bool free_list_only,
6377 HeapRegionSet* old_set, FreeRegionList* free_list) :
6378 _free_list_only(free_list_only),
6379 _old_set(old_set), _free_list(free_list), _total_used(0) {
6380 assert(_free_list->is_empty(), "pre-condition");
6381 if (!free_list_only) {
6382 assert(_old_set->is_empty(), "pre-condition");
6383 }
6384 }
6385
6386 bool doHeapRegion(HeapRegion* r) {
6387 if (r->continuesHumongous()) {
6388 return false;
6389 }
6390
6391 if (r->is_empty()) {
6392 // Add free regions to the free list
6393 _free_list->add_as_tail(r);
6394 } else if (!_free_list_only) {
6395 assert(!r->is_young(), "we should not come across young regions");
6396
6397 if (r->isHumongous()) {
6398 // We ignore humongous regions, we left the humongous set unchanged
6399 } else {
6400 // The rest should be old, add them to the old set
6401 _old_set->add(r);
6402 }
6403 _total_used += r->used();
6404 }
6405
6406 return false;
6407 }
6408
6409 size_t total_used() {
6410 return _total_used;
6411 }
6412 };
6413
6414 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6415 assert_at_safepoint(true /* should_be_vm_thread */);
6416
6417 if (!free_list_only) {
6418 _young_list->empty_list();
6419 }
6420
6421 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6422 heap_region_iterate(&cl);
6423
6424 if (!free_list_only) {
6425 _summary_bytes_used = cl.total_used();
6426 }
6427 assert(_summary_bytes_used == recalculate_used(),
6428 err_msg("inconsistent _summary_bytes_used, "
6429 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6430 _summary_bytes_used, recalculate_used()));
6431 }
6432
6433 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6434 _refine_cte_cl->set_concurrent(concurrent);
6435 }
6436
6437 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6438 HeapRegion* hr = heap_region_containing(p);
6439 if (hr == NULL) {
6440 return false;
6441 } else {
6442 return hr->is_in(p);
6443 }
6444 }
6445
6446 // Methods for the mutator alloc region
6447
6448 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6449 bool force) {
6450 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6451 assert(!force || g1_policy()->can_expand_young_list(),
6452 "if force is true we should be able to expand the young list");
6453 bool young_list_full = g1_policy()->is_young_list_full();
6454 if (force || !young_list_full) {
6455 HeapRegion* new_alloc_region = new_region(word_size,
6456 false /* is_old */,
6457 false /* do_expand */);
6458 if (new_alloc_region != NULL) {
6459 set_region_short_lived_locked(new_alloc_region);
6460 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6461 return new_alloc_region;
6462 }
6463 }
6464 return NULL;
6465 }
6466
6467 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6468 size_t allocated_bytes) {
6469 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6470 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6471
6472 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6473 _summary_bytes_used += allocated_bytes;
6474 _hr_printer.retire(alloc_region);
6475 // We update the eden sizes here, when the region is retired,
6476 // instead of when it's allocated, since this is the point that its
6477 // used space has been recored in _summary_bytes_used.
6478 g1mm()->update_eden_size();
6479 }
6480
6481 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6482 bool force) {
6483 return _g1h->new_mutator_alloc_region(word_size, force);
6484 }
6485
6486 void G1CollectedHeap::set_par_threads() {
6487 // Don't change the number of workers. Use the value previously set
6488 // in the workgroup.
6489 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6490 uint n_workers = workers()->active_workers();
6491 assert(UseDynamicNumberOfGCThreads ||
6492 n_workers == workers()->total_workers(),
6493 "Otherwise should be using the total number of workers");
6494 if (n_workers == 0) {
6495 assert(false, "Should have been set in prior evacuation pause.");
6496 n_workers = ParallelGCThreads;
6497 workers()->set_active_workers(n_workers);
6498 }
6499 set_par_threads(n_workers);
6500 }
6501
6502 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6503 size_t allocated_bytes) {
6504 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6505 }
6506
6507 // Methods for the GC alloc regions
6508
6509 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6510 uint count,
6511 GCAllocPurpose ap) {
6512 assert(FreeList_lock->owned_by_self(), "pre-condition");
6513
6514 if (count < g1_policy()->max_regions(ap)) {
6515 bool survivor = (ap == GCAllocForSurvived);
6516 HeapRegion* new_alloc_region = new_region(word_size,
6517 !survivor,
6518 true /* do_expand */);
6519 if (new_alloc_region != NULL) {
6520 // We really only need to do this for old regions given that we
6521 // should never scan survivors. But it doesn't hurt to do it
6522 // for survivors too.
6523 new_alloc_region->set_saved_mark();
6524 if (survivor) {
6525 new_alloc_region->set_survivor();
6526 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6527 } else {
6528 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6529 }
6530 bool during_im = g1_policy()->during_initial_mark_pause();
6531 new_alloc_region->note_start_of_copying(during_im);
6532 return new_alloc_region;
6533 } else {
6534 g1_policy()->note_alloc_region_limit_reached(ap);
6535 }
6536 }
6537 return NULL;
6538 }
6539
6540 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6541 size_t allocated_bytes,
6542 GCAllocPurpose ap) {
6543 bool during_im = g1_policy()->during_initial_mark_pause();
6544 alloc_region->note_end_of_copying(during_im);
6545 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6546 if (ap == GCAllocForSurvived) {
6547 young_list()->add_survivor_region(alloc_region);
6548 } else {
6549 _old_set.add(alloc_region);
6550 }
6551 _hr_printer.retire(alloc_region);
6552 }
6553
6554 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6555 bool force) {
6556 assert(!force, "not supported for GC alloc regions");
6557 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6558 }
6559
6560 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6561 size_t allocated_bytes) {
6562 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6563 GCAllocForSurvived);
6564 }
6565
6566 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6567 bool force) {
6568 assert(!force, "not supported for GC alloc regions");
6569 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6570 }
6571
6572 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6573 size_t allocated_bytes) {
6574 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6575 GCAllocForTenured);
6576 }
6577 // Heap region set verification
6578
6579 class VerifyRegionListsClosure : public HeapRegionClosure {
6580 private:
6581 HeapRegionSet* _old_set;
6582 HeapRegionSet* _humongous_set;
6583 FreeRegionList* _free_list;
6584
6585 public:
6586 HeapRegionSetCount _old_count;
6587 HeapRegionSetCount _humongous_count;
6588 HeapRegionSetCount _free_count;
6589
6590 VerifyRegionListsClosure(HeapRegionSet* old_set,
6591 HeapRegionSet* humongous_set,
6592 FreeRegionList* free_list) :
6593 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6594 _old_count(), _humongous_count(), _free_count(){ }
6595
6596 bool doHeapRegion(HeapRegion* hr) {
6597 if (hr->continuesHumongous()) {
6598 return false;
6599 }
6600
6601 if (hr->is_young()) {
6602 // TODO
6603 } else if (hr->startsHumongous()) {
6604 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6605 _humongous_count.increment(1u, hr->capacity());
6606 } else if (hr->is_empty()) {
6607 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6608 _free_count.increment(1u, hr->capacity());
6609 } else {
6610 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6611 _old_count.increment(1u, hr->capacity());
6612 }
6613 return false;
6614 }
6615
6616 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6617 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6618 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6619 old_set->total_capacity_bytes(), _old_count.capacity()));
6620
6621 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6622 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6623 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6624
6625 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6626 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6627 free_list->total_capacity_bytes(), _free_count.capacity()));
6628 }
6629 };
6630
6631 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6632 HeapWord* bottom) {
6633 HeapWord* end = bottom + HeapRegion::GrainWords;
6634 MemRegion mr(bottom, end);
6635 assert(_g1_reserved.contains(mr), "invariant");
6636 // This might return NULL if the allocation fails
6637 return new HeapRegion(hrs_index, _bot_shared, mr);
6638 }
6639
6640 void G1CollectedHeap::verify_region_sets() {
6641 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6642
6643 // First, check the explicit lists.
6644 _free_list.verify_list();
6645 {
6646 // Given that a concurrent operation might be adding regions to
6647 // the secondary free list we have to take the lock before
6648 // verifying it.
6649 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6650 _secondary_free_list.verify_list();
6651 }
6652
6653 // If a concurrent region freeing operation is in progress it will
6654 // be difficult to correctly attributed any free regions we come
6655 // across to the correct free list given that they might belong to
6656 // one of several (free_list, secondary_free_list, any local lists,
6657 // etc.). So, if that's the case we will skip the rest of the
6658 // verification operation. Alternatively, waiting for the concurrent
6659 // operation to complete will have a non-trivial effect on the GC's
6660 // operation (no concurrent operation will last longer than the
6661 // interval between two calls to verification) and it might hide
6662 // any issues that we would like to catch during testing.
6663 if (free_regions_coming()) {
6664 return;
6665 }
6666
6667 // Make sure we append the secondary_free_list on the free_list so
6668 // that all free regions we will come across can be safely
6669 // attributed to the free_list.
6670 append_secondary_free_list_if_not_empty_with_lock();
6671
6672 // Finally, make sure that the region accounting in the lists is
6673 // consistent with what we see in the heap.
6674
6675 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6676 heap_region_iterate(&cl);
6677 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6678 }
6679
6680 // Optimized nmethod scanning
6681
6682 class RegisterNMethodOopClosure: public OopClosure {
6683 G1CollectedHeap* _g1h;
6684 nmethod* _nm;
6685
6686 template <class T> void do_oop_work(T* p) {
6687 T heap_oop = oopDesc::load_heap_oop(p);
6688 if (!oopDesc::is_null(heap_oop)) {
6689 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6690 HeapRegion* hr = _g1h->heap_region_containing(obj);
6691 assert(!hr->continuesHumongous(),
6692 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6693 " starting at "HR_FORMAT,
6694 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6695
6696 // HeapRegion::add_strong_code_root() avoids adding duplicate
6697 // entries but having duplicates is OK since we "mark" nmethods
6698 // as visited when we scan the strong code root lists during the GC.
6699 hr->add_strong_code_root(_nm);
6700 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6701 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6702 _nm, HR_FORMAT_PARAMS(hr)));
6703 }
6704 }
6705
6706 public:
6707 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6708 _g1h(g1h), _nm(nm) {}
6709
6710 void do_oop(oop* p) { do_oop_work(p); }
6711 void do_oop(narrowOop* p) { do_oop_work(p); }
6712 };
6713
6714 class UnregisterNMethodOopClosure: public OopClosure {
6715 G1CollectedHeap* _g1h;
6716 nmethod* _nm;
6717
6718 template <class T> void do_oop_work(T* p) {
6719 T heap_oop = oopDesc::load_heap_oop(p);
6720 if (!oopDesc::is_null(heap_oop)) {
6721 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6722 HeapRegion* hr = _g1h->heap_region_containing(obj);
6723 assert(!hr->continuesHumongous(),
6724 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6725 " starting at "HR_FORMAT,
6726 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6727
6728 hr->remove_strong_code_root(_nm);
6729 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6730 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6731 _nm, HR_FORMAT_PARAMS(hr)));
6732 }
6733 }
6734
6735 public:
6736 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6737 _g1h(g1h), _nm(nm) {}
6738
6739 void do_oop(oop* p) { do_oop_work(p); }
6740 void do_oop(narrowOop* p) { do_oop_work(p); }
6741 };
6742
6743 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6744 CollectedHeap::register_nmethod(nm);
6745
6746 guarantee(nm != NULL, "sanity");
6747 RegisterNMethodOopClosure reg_cl(this, nm);
6748 nm->oops_do(®_cl);
6749 }
6750
6751 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6752 CollectedHeap::unregister_nmethod(nm);
6753
6754 guarantee(nm != NULL, "sanity");
6755 UnregisterNMethodOopClosure reg_cl(this, nm);
6756 nm->oops_do(®_cl, true);
6757 }
6758
6759 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6760 public:
6761 bool doHeapRegion(HeapRegion *hr) {
6762 assert(!hr->isHumongous(),
6763 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6764 HR_FORMAT_PARAMS(hr)));
6765 hr->migrate_strong_code_roots();
6766 return false;
6767 }
6768 };
6769
6770 void G1CollectedHeap::migrate_strong_code_roots() {
6771 MigrateCodeRootsHeapRegionClosure cl;
6772 double migrate_start = os::elapsedTime();
6773 collection_set_iterate(&cl);
6774 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6775 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6776 }
6777
6778 void G1CollectedHeap::purge_code_root_memory() {
6779 double purge_start = os::elapsedTime();
6780 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6781 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6782 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6783 }
6784
6785 // Mark all the code roots that point into regions *not* in the
6786 // collection set.
6787 //
6788 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6789 // walking the the code roots lists of regions not in the collection
6790 // set. Suppose we have an nmethod (M) that points to objects in two
6791 // separate regions - one in the collection set (R1) and one not (R2).
6792 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6793 // nmethod M when walking the code roots for R1. When we come to scan
6794 // the code roots for R2, we would see that M is already marked and it
6795 // would be skipped and the objects in R2 that are referenced from M
6796 // would not be evacuated.
6797
6798 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6799
6800 class MarkStrongCodeRootOopClosure: public OopClosure {
6801 ConcurrentMark* _cm;
6802 HeapRegion* _hr;
6803 uint _worker_id;
6804
6805 template <class T> void do_oop_work(T* p) {
6806 T heap_oop = oopDesc::load_heap_oop(p);
6807 if (!oopDesc::is_null(heap_oop)) {
6808 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6809 // Only mark objects in the region (which is assumed
6810 // to be not in the collection set).
6811 if (_hr->is_in(obj)) {
6812 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6813 }
6814 }
6815 }
6816
6817 public:
6818 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6819 _cm(cm), _hr(hr), _worker_id(worker_id) {
6820 assert(!_hr->in_collection_set(), "sanity");
6821 }
6822
6823 void do_oop(narrowOop* p) { do_oop_work(p); }
6824 void do_oop(oop* p) { do_oop_work(p); }
6825 };
6826
6827 MarkStrongCodeRootOopClosure _oop_cl;
6828
6829 public:
6830 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6831 _oop_cl(cm, hr, worker_id) {}
6832
6833 void do_code_blob(CodeBlob* cb) {
6834 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6835 if (nm != NULL) {
6836 nm->oops_do(&_oop_cl);
6837 }
6838 }
6839 };
6840
6841 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6842 G1CollectedHeap* _g1h;
6843 uint _worker_id;
6844
6845 public:
6846 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6847 _g1h(g1h), _worker_id(worker_id) {}
6848
6849 bool doHeapRegion(HeapRegion *hr) {
6850 HeapRegionRemSet* hrrs = hr->rem_set();
6851 if (hr->continuesHumongous()) {
6852 // Code roots should never be attached to a continuation of a humongous region
6853 assert(hrrs->strong_code_roots_list_length() == 0,
6854 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6855 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6856 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6857 hrrs->strong_code_roots_list_length()));
6858 return false;
6859 }
6860
6861 if (hr->in_collection_set()) {
6862 // Don't mark code roots into regions in the collection set here.
6863 // They will be marked when we scan them.
6864 return false;
6865 }
6866
6867 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6868 hr->strong_code_roots_do(&cb_cl);
6869 return false;
6870 }
6871 };
6872
6873 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6874 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6875 if (G1CollectedHeap::use_parallel_gc_threads()) {
6876 heap_region_par_iterate_chunked(&cl,
6877 worker_id,
6878 workers()->active_workers(),
6879 HeapRegion::ParMarkRootClaimValue);
6880 } else {
6881 heap_region_iterate(&cl);
6882 }
6883 }
6884
6885 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6886 G1CollectedHeap* _g1h;
6887
6888 public:
6889 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6890 _g1h(g1h) {}
6891
6892 void do_code_blob(CodeBlob* cb) {
6893 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6894 if (nm == NULL) {
6895 return;
6896 }
6897
6898 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6899 _g1h->register_nmethod(nm);
6900 }
6901 }
6902 };
6903
6904 void G1CollectedHeap::rebuild_strong_code_roots() {
6905 RebuildStrongCodeRootClosure blob_cl(this);
6906 CodeCache::blobs_do(&blob_cl);
6907 }