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 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/stringTable.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "gc_implementation/g1/bufferingOopClosure.hpp"
35 #include "gc_implementation/g1/concurrentG1Refine.hpp"
36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
40 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
41 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
42 #include "gc_implementation/g1/g1EvacFailure.hpp"
43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
44 #include "gc_implementation/g1/g1Log.hpp"
45 #include "gc_implementation/g1/g1MarkSweep.hpp"
46 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
47 #include "gc_implementation/g1/g1RemSet.inline.hpp"
48 #include "gc_implementation/g1/g1StringDedup.hpp"
49 #include "gc_implementation/g1/g1YCTypes.hpp"
50 #include "gc_implementation/g1/heapRegion.inline.hpp"
51 #include "gc_implementation/g1/heapRegionRemSet.hpp"
52 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
53 #include "gc_implementation/g1/vm_operations_g1.hpp"
54 #include "gc_implementation/shared/gcHeapSummary.hpp"
55 #include "gc_implementation/shared/gcTimer.hpp"
56 #include "gc_implementation/shared/gcTrace.hpp"
57 #include "gc_implementation/shared/gcTraceTime.hpp"
58 #include "gc_implementation/shared/isGCActiveMark.hpp"
59 #include "memory/gcLocker.inline.hpp"
60 #include "memory/generationSpec.hpp"
61 #include "memory/iterator.hpp"
62 #include "memory/referenceProcessor.hpp"
63 #include "oops/oop.inline.hpp"
64 #include "oops/oop.pcgc.inline.hpp"
65 #include "runtime/prefetch.inline.hpp"
66 #include "runtime/orderAccess.inline.hpp"
67 #include "runtime/vmThread.hpp"
68 #include "utilities/globalDefinitions.hpp"
69 #include "utilities/ticks.hpp"
70
71 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
72
73 // turn it on so that the contents of the young list (scan-only /
74 // to-be-collected) are printed at "strategic" points before / during
75 // / after the collection --- this is useful for debugging
76 #define YOUNG_LIST_VERBOSE 0
77 // CURRENT STATUS
78 // This file is under construction. Search for "FIXME".
79
80 // INVARIANTS/NOTES
81 //
82 // All allocation activity covered by the G1CollectedHeap interface is
83 // serialized by acquiring the HeapLock. This happens in mem_allocate
84 // and allocate_new_tlab, which are the "entry" points to the
85 // allocation code from the rest of the JVM. (Note that this does not
86 // apply to TLAB allocation, which is not part of this interface: it
87 // is done by clients of this interface.)
88
89 // Notes on implementation of parallelism in different tasks.
90 //
91 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
92 // The number of GC workers is passed to heap_region_par_iterate_chunked().
93 // It does use run_task() which sets _n_workers in the task.
94 // G1ParTask executes g1_process_strong_roots() ->
95 // SharedHeap::process_strong_roots() which calls eventually to
96 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
97 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
98 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
99 //
100
101 // Local to this file.
102
103 class RefineCardTableEntryClosure: public CardTableEntryClosure {
104 bool _concurrent;
105 public:
106 RefineCardTableEntryClosure() : _concurrent(true) { }
107
108 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
109 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
110 // This path is executed by the concurrent refine or mutator threads,
111 // concurrently, and so we do not care if card_ptr contains references
112 // that point into the collection set.
113 assert(!oops_into_cset, "should be");
114
115 if (_concurrent && SuspendibleThreadSet::should_yield()) {
116 // Caller will actually yield.
117 return false;
118 }
119 // Otherwise, we finished successfully; return true.
120 return true;
121 }
122
123 void set_concurrent(bool b) { _concurrent = b; }
124 };
125
126
127 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
128 size_t _num_processed;
129 CardTableModRefBS* _ctbs;
130 int _histo[256];
131
132 public:
133 ClearLoggedCardTableEntryClosure() :
134 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
135 {
136 for (int i = 0; i < 256; i++) _histo[i] = 0;
137 }
138
139 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
140 unsigned char* ujb = (unsigned char*)card_ptr;
141 int ind = (int)(*ujb);
142 _histo[ind]++;
143
144 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
145 _num_processed++;
146
147 return true;
148 }
149
150 size_t num_processed() { return _num_processed; }
151
152 void print_histo() {
153 gclog_or_tty->print_cr("Card table value histogram:");
154 for (int i = 0; i < 256; i++) {
155 if (_histo[i] != 0) {
156 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
157 }
158 }
159 }
160 };
161
162 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
163 private:
164 size_t _num_processed;
165
166 public:
167 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
168
169 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
170 *card_ptr = CardTableModRefBS::dirty_card_val();
171 _num_processed++;
172 return true;
173 }
174
175 size_t num_processed() const { return _num_processed; }
176 };
177
178 YoungList::YoungList(G1CollectedHeap* g1h) :
179 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
180 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
181 guarantee(check_list_empty(false), "just making sure...");
182 }
183
184 void YoungList::push_region(HeapRegion *hr) {
185 assert(!hr->is_young(), "should not already be young");
186 assert(hr->get_next_young_region() == NULL, "cause it should!");
187
188 hr->set_next_young_region(_head);
189 _head = hr;
190
191 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
192 ++_length;
193 }
194
195 void YoungList::add_survivor_region(HeapRegion* hr) {
196 assert(hr->is_survivor(), "should be flagged as survivor region");
197 assert(hr->get_next_young_region() == NULL, "cause it should!");
198
199 hr->set_next_young_region(_survivor_head);
200 if (_survivor_head == NULL) {
201 _survivor_tail = hr;
202 }
203 _survivor_head = hr;
204 ++_survivor_length;
205 }
206
207 void YoungList::empty_list(HeapRegion* list) {
208 while (list != NULL) {
209 HeapRegion* next = list->get_next_young_region();
210 list->set_next_young_region(NULL);
211 list->uninstall_surv_rate_group();
212 list->set_not_young();
213 list = next;
214 }
215 }
216
217 void YoungList::empty_list() {
218 assert(check_list_well_formed(), "young list should be well formed");
219
220 empty_list(_head);
221 _head = NULL;
222 _length = 0;
223
224 empty_list(_survivor_head);
225 _survivor_head = NULL;
226 _survivor_tail = NULL;
227 _survivor_length = 0;
228
229 _last_sampled_rs_lengths = 0;
230
231 assert(check_list_empty(false), "just making sure...");
232 }
233
234 bool YoungList::check_list_well_formed() {
235 bool ret = true;
236
237 uint length = 0;
238 HeapRegion* curr = _head;
239 HeapRegion* last = NULL;
240 while (curr != NULL) {
241 if (!curr->is_young()) {
242 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
243 "incorrectly tagged (y: %d, surv: %d)",
244 curr->bottom(), curr->end(),
245 curr->is_young(), curr->is_survivor());
246 ret = false;
247 }
248 ++length;
249 last = curr;
250 curr = curr->get_next_young_region();
251 }
252 ret = ret && (length == _length);
253
254 if (!ret) {
255 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
256 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
257 length, _length);
258 }
259
260 return ret;
261 }
262
263 bool YoungList::check_list_empty(bool check_sample) {
264 bool ret = true;
265
266 if (_length != 0) {
267 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
268 _length);
269 ret = false;
270 }
271 if (check_sample && _last_sampled_rs_lengths != 0) {
272 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
273 ret = false;
274 }
275 if (_head != NULL) {
276 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
277 ret = false;
278 }
279 if (!ret) {
280 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
281 }
282
283 return ret;
284 }
285
286 void
287 YoungList::rs_length_sampling_init() {
288 _sampled_rs_lengths = 0;
289 _curr = _head;
290 }
291
292 bool
293 YoungList::rs_length_sampling_more() {
294 return _curr != NULL;
295 }
296
297 void
298 YoungList::rs_length_sampling_next() {
299 assert( _curr != NULL, "invariant" );
300 size_t rs_length = _curr->rem_set()->occupied();
301
302 _sampled_rs_lengths += rs_length;
303
304 // The current region may not yet have been added to the
305 // incremental collection set (it gets added when it is
306 // retired as the current allocation region).
307 if (_curr->in_collection_set()) {
308 // Update the collection set policy information for this region
309 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
310 }
311
312 _curr = _curr->get_next_young_region();
313 if (_curr == NULL) {
314 _last_sampled_rs_lengths = _sampled_rs_lengths;
315 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
316 }
317 }
318
319 void
320 YoungList::reset_auxilary_lists() {
321 guarantee( is_empty(), "young list should be empty" );
322 assert(check_list_well_formed(), "young list should be well formed");
323
324 // Add survivor regions to SurvRateGroup.
325 _g1h->g1_policy()->note_start_adding_survivor_regions();
326 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
327
328 int young_index_in_cset = 0;
329 for (HeapRegion* curr = _survivor_head;
330 curr != NULL;
331 curr = curr->get_next_young_region()) {
332 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
333
334 // The region is a non-empty survivor so let's add it to
335 // the incremental collection set for the next evacuation
336 // pause.
337 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
338 young_index_in_cset += 1;
339 }
340 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
341 _g1h->g1_policy()->note_stop_adding_survivor_regions();
342
343 _head = _survivor_head;
344 _length = _survivor_length;
345 if (_survivor_head != NULL) {
346 assert(_survivor_tail != NULL, "cause it shouldn't be");
347 assert(_survivor_length > 0, "invariant");
348 _survivor_tail->set_next_young_region(NULL);
349 }
350
351 // Don't clear the survivor list handles until the start of
352 // the next evacuation pause - we need it in order to re-tag
353 // the survivor regions from this evacuation pause as 'young'
354 // at the start of the next.
355
356 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
357
358 assert(check_list_well_formed(), "young list should be well formed");
359 }
360
361 void YoungList::print() {
362 HeapRegion* lists[] = {_head, _survivor_head};
363 const char* names[] = {"YOUNG", "SURVIVOR"};
364
365 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
366 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
367 HeapRegion *curr = lists[list];
368 if (curr == NULL)
369 gclog_or_tty->print_cr(" empty");
370 while (curr != NULL) {
371 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
372 HR_FORMAT_PARAMS(curr),
373 curr->prev_top_at_mark_start(),
374 curr->next_top_at_mark_start(),
375 curr->age_in_surv_rate_group_cond());
376 curr = curr->get_next_young_region();
377 }
378 }
379
380 gclog_or_tty->cr();
381 }
382
383 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
384 {
385 // Claim the right to put the region on the dirty cards region list
386 // by installing a self pointer.
387 HeapRegion* next = hr->get_next_dirty_cards_region();
388 if (next == NULL) {
389 HeapRegion* res = (HeapRegion*)
390 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
391 NULL);
392 if (res == NULL) {
393 HeapRegion* head;
394 do {
395 // Put the region to the dirty cards region list.
396 head = _dirty_cards_region_list;
397 next = (HeapRegion*)
398 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
399 if (next == head) {
400 assert(hr->get_next_dirty_cards_region() == hr,
401 "hr->get_next_dirty_cards_region() != hr");
402 if (next == NULL) {
403 // The last region in the list points to itself.
404 hr->set_next_dirty_cards_region(hr);
405 } else {
406 hr->set_next_dirty_cards_region(next);
407 }
408 }
409 } while (next != head);
410 }
411 }
412 }
413
414 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
415 {
416 HeapRegion* head;
417 HeapRegion* hr;
418 do {
419 head = _dirty_cards_region_list;
420 if (head == NULL) {
421 return NULL;
422 }
423 HeapRegion* new_head = head->get_next_dirty_cards_region();
424 if (head == new_head) {
425 // The last region.
426 new_head = NULL;
427 }
428 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
429 head);
430 } while (hr != head);
431 assert(hr != NULL, "invariant");
432 hr->set_next_dirty_cards_region(NULL);
433 return hr;
434 }
435
436 void G1CollectedHeap::stop_conc_gc_threads() {
437 _cg1r->stop();
438 _cmThread->stop();
439 if (G1StringDedup::is_enabled()) {
440 G1StringDedup::stop();
441 }
442 }
443
444 #ifdef ASSERT
445 // A region is added to the collection set as it is retired
446 // so an address p can point to a region which will be in the
447 // collection set but has not yet been retired. This method
448 // therefore is only accurate during a GC pause after all
449 // regions have been retired. It is used for debugging
450 // to check if an nmethod has references to objects that can
451 // be move during a partial collection. Though it can be
452 // inaccurate, it is sufficient for G1 because the conservative
453 // implementation of is_scavengable() for G1 will indicate that
454 // all nmethods must be scanned during a partial collection.
455 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
456 if (p == NULL) {
457 return false;
458 }
459 return heap_region_containing(p)->in_collection_set();
460 }
461 #endif
462
463 // Returns true if the reference points to an object that
464 // can move in an incremental collection.
465 bool G1CollectedHeap::is_scavengable(const void* p) {
466 HeapRegion* hr = heap_region_containing(p);
467 return !hr->isHumongous();
468 }
469
470 void G1CollectedHeap::check_ct_logs_at_safepoint() {
471 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
472 CardTableModRefBS* ct_bs = g1_barrier_set();
473
474 // Count the dirty cards at the start.
475 CountNonCleanMemRegionClosure count1(this);
476 ct_bs->mod_card_iterate(&count1);
477 int orig_count = count1.n();
478
479 // First clear the logged cards.
480 ClearLoggedCardTableEntryClosure clear;
481 dcqs.apply_closure_to_all_completed_buffers(&clear);
482 dcqs.iterate_closure_all_threads(&clear, false);
483 clear.print_histo();
484
485 // Now ensure that there's no dirty cards.
486 CountNonCleanMemRegionClosure count2(this);
487 ct_bs->mod_card_iterate(&count2);
488 if (count2.n() != 0) {
489 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
490 count2.n(), orig_count);
491 }
492 guarantee(count2.n() == 0, "Card table should be clean.");
493
494 RedirtyLoggedCardTableEntryClosure redirty;
495 dcqs.apply_closure_to_all_completed_buffers(&redirty);
496 dcqs.iterate_closure_all_threads(&redirty, false);
497 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
498 clear.num_processed(), orig_count);
499 guarantee(redirty.num_processed() == clear.num_processed(),
500 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
501 redirty.num_processed(), clear.num_processed()));
502
503 CountNonCleanMemRegionClosure count3(this);
504 ct_bs->mod_card_iterate(&count3);
505 if (count3.n() != orig_count) {
506 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
507 orig_count, count3.n());
508 guarantee(count3.n() >= orig_count, "Should have restored them all.");
509 }
510 }
511
512 // Private class members.
513
514 G1CollectedHeap* G1CollectedHeap::_g1h;
515
516 // Private methods.
517
518 HeapRegion*
519 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
520 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
521 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
522 if (!_secondary_free_list.is_empty()) {
523 if (G1ConcRegionFreeingVerbose) {
524 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
525 "secondary_free_list has %u entries",
526 _secondary_free_list.length());
527 }
528 // It looks as if there are free regions available on the
529 // secondary_free_list. Let's move them to the free_list and try
530 // again to allocate from it.
531 append_secondary_free_list();
532
533 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
534 "empty we should have moved at least one entry to the free_list");
535 HeapRegion* res = _free_list.remove_region(is_old);
536 if (G1ConcRegionFreeingVerbose) {
537 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
538 "allocated "HR_FORMAT" from secondary_free_list",
539 HR_FORMAT_PARAMS(res));
540 }
541 return res;
542 }
543
544 // Wait here until we get notified either when (a) there are no
545 // more free regions coming or (b) some regions have been moved on
546 // the secondary_free_list.
547 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
548 }
549
550 if (G1ConcRegionFreeingVerbose) {
551 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
552 "could not allocate from secondary_free_list");
553 }
554 return NULL;
555 }
556
557 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
558 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
559 "the only time we use this to allocate a humongous region is "
560 "when we are allocating a single humongous region");
561
562 HeapRegion* res;
563 if (G1StressConcRegionFreeing) {
564 if (!_secondary_free_list.is_empty()) {
565 if (G1ConcRegionFreeingVerbose) {
566 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
567 "forced to look at the secondary_free_list");
568 }
569 res = new_region_try_secondary_free_list(is_old);
570 if (res != NULL) {
571 return res;
572 }
573 }
574 }
575
576 res = _free_list.remove_region(is_old);
577
578 if (res == NULL) {
579 if (G1ConcRegionFreeingVerbose) {
580 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
581 "res == NULL, trying the secondary_free_list");
582 }
583 res = new_region_try_secondary_free_list(is_old);
584 }
585 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
586 // Currently, only attempts to allocate GC alloc regions set
587 // do_expand to true. So, we should only reach here during a
588 // safepoint. If this assumption changes we might have to
589 // reconsider the use of _expand_heap_after_alloc_failure.
590 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
591
592 ergo_verbose1(ErgoHeapSizing,
593 "attempt heap expansion",
594 ergo_format_reason("region allocation request failed")
595 ergo_format_byte("allocation request"),
596 word_size * HeapWordSize);
597 if (expand(word_size * HeapWordSize)) {
598 // Given that expand() succeeded in expanding the heap, and we
599 // always expand the heap by an amount aligned to the heap
600 // region size, the free list should in theory not be empty.
601 // In either case remove_region() will check for NULL.
602 res = _free_list.remove_region(is_old);
603 } else {
604 _expand_heap_after_alloc_failure = false;
605 }
606 }
607 return res;
608 }
609
610 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
611 size_t word_size) {
612 assert(isHumongous(word_size), "word_size should be humongous");
613 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
614
615 uint first = G1_NULL_HRS_INDEX;
616 if (num_regions == 1) {
617 // Only one region to allocate, no need to go through the slower
618 // path. The caller will attempt the expansion if this fails, so
619 // let's not try to expand here too.
620 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
621 if (hr != NULL) {
622 first = hr->hrs_index();
623 } else {
624 first = G1_NULL_HRS_INDEX;
625 }
626 } else {
627 // We can't allocate humongous regions while cleanupComplete() is
628 // running, since some of the regions we find to be empty might not
629 // yet be added to the free list and it is not straightforward to
630 // know which list they are on so that we can remove them. Note
631 // that we only need to do this if we need to allocate more than
632 // one region to satisfy the current humongous allocation
633 // request. If we are only allocating one region we use the common
634 // region allocation code (see above).
635 wait_while_free_regions_coming();
636 append_secondary_free_list_if_not_empty_with_lock();
637
638 if (free_regions() >= num_regions) {
639 first = _hrs.find_contiguous(num_regions);
640 if (first != G1_NULL_HRS_INDEX) {
641 for (uint i = first; i < first + num_regions; ++i) {
642 HeapRegion* hr = region_at(i);
643 assert(hr->is_empty(), "sanity");
644 assert(is_on_master_free_list(hr), "sanity");
645 hr->set_pending_removal(true);
646 }
647 _free_list.remove_all_pending(num_regions);
648 }
649 }
650 }
651 return first;
652 }
653
654 HeapWord*
655 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
656 uint num_regions,
657 size_t word_size) {
658 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
659 assert(isHumongous(word_size), "word_size should be humongous");
660 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
661
662 // Index of last region in the series + 1.
663 uint last = first + num_regions;
664
665 // We need to initialize the region(s) we just discovered. This is
666 // a bit tricky given that it can happen concurrently with
667 // refinement threads refining cards on these regions and
668 // potentially wanting to refine the BOT as they are scanning
669 // those cards (this can happen shortly after a cleanup; see CR
670 // 6991377). So we have to set up the region(s) carefully and in
671 // a specific order.
672
673 // The word size sum of all the regions we will allocate.
674 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
675 assert(word_size <= word_size_sum, "sanity");
676
677 // This will be the "starts humongous" region.
678 HeapRegion* first_hr = region_at(first);
679 // The header of the new object will be placed at the bottom of
680 // the first region.
681 HeapWord* new_obj = first_hr->bottom();
682 // This will be the new end of the first region in the series that
683 // should also match the end of the last region in the series.
684 HeapWord* new_end = new_obj + word_size_sum;
685 // This will be the new top of the first region that will reflect
686 // this allocation.
687 HeapWord* new_top = new_obj + word_size;
688
689 // First, we need to zero the header of the space that we will be
690 // allocating. When we update top further down, some refinement
691 // threads might try to scan the region. By zeroing the header we
692 // ensure that any thread that will try to scan the region will
693 // come across the zero klass word and bail out.
694 //
695 // NOTE: It would not have been correct to have used
696 // CollectedHeap::fill_with_object() and make the space look like
697 // an int array. The thread that is doing the allocation will
698 // later update the object header to a potentially different array
699 // type and, for a very short period of time, the klass and length
700 // fields will be inconsistent. This could cause a refinement
701 // thread to calculate the object size incorrectly.
702 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
703
704 // We will set up the first region as "starts humongous". This
705 // will also update the BOT covering all the regions to reflect
706 // that there is a single object that starts at the bottom of the
707 // first region.
708 first_hr->set_startsHumongous(new_top, new_end);
709
710 // Then, if there are any, we will set up the "continues
711 // humongous" regions.
712 HeapRegion* hr = NULL;
713 for (uint i = first + 1; i < last; ++i) {
714 hr = region_at(i);
715 hr->set_continuesHumongous(first_hr);
716 }
717 // If we have "continues humongous" regions (hr != NULL), then the
718 // end of the last one should match new_end.
719 assert(hr == NULL || hr->end() == new_end, "sanity");
720
721 // Up to this point no concurrent thread would have been able to
722 // do any scanning on any region in this series. All the top
723 // fields still point to bottom, so the intersection between
724 // [bottom,top] and [card_start,card_end] will be empty. Before we
725 // update the top fields, we'll do a storestore to make sure that
726 // no thread sees the update to top before the zeroing of the
727 // object header and the BOT initialization.
728 OrderAccess::storestore();
729
730 // Now that the BOT and the object header have been initialized,
731 // we can update top of the "starts humongous" region.
732 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
733 "new_top should be in this region");
734 first_hr->set_top(new_top);
735 if (_hr_printer.is_active()) {
736 HeapWord* bottom = first_hr->bottom();
737 HeapWord* end = first_hr->orig_end();
738 if ((first + 1) == last) {
739 // the series has a single humongous region
740 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
741 } else {
742 // the series has more than one humongous regions
743 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
744 }
745 }
746
747 // Now, we will update the top fields of the "continues humongous"
748 // regions. The reason we need to do this is that, otherwise,
749 // these regions would look empty and this will confuse parts of
750 // G1. For example, the code that looks for a consecutive number
751 // of empty regions will consider them empty and try to
752 // re-allocate them. We can extend is_empty() to also include
753 // !continuesHumongous(), but it is easier to just update the top
754 // fields here. The way we set top for all regions (i.e., top ==
755 // end for all regions but the last one, top == new_top for the
756 // last one) is actually used when we will free up the humongous
757 // region in free_humongous_region().
758 hr = NULL;
759 for (uint i = first + 1; i < last; ++i) {
760 hr = region_at(i);
761 if ((i + 1) == last) {
762 // last continues humongous region
763 assert(hr->bottom() < new_top && new_top <= hr->end(),
764 "new_top should fall on this region");
765 hr->set_top(new_top);
766 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
767 } else {
768 // not last one
769 assert(new_top > hr->end(), "new_top should be above this region");
770 hr->set_top(hr->end());
771 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
772 }
773 }
774 // If we have continues humongous regions (hr != NULL), then the
775 // end of the last one should match new_end and its top should
776 // match new_top.
777 assert(hr == NULL ||
778 (hr->end() == new_end && hr->top() == new_top), "sanity");
779 check_bitmaps("Humongous Region Allocation", first_hr);
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 check_bitmaps("Full GC Start");
1339 pre_full_gc_dump(gc_timer);
1340
1341 COMPILER2_PRESENT(DerivedPointerTable::clear());
1342
1343 // Disable discovery and empty the discovered lists
1344 // for the CM ref processor.
1345 ref_processor_cm()->disable_discovery();
1346 ref_processor_cm()->abandon_partial_discovery();
1347 ref_processor_cm()->verify_no_references_recorded();
1348
1349 // Abandon current iterations of concurrent marking and concurrent
1350 // refinement, if any are in progress. We have to do this before
1351 // wait_until_scan_finished() below.
1352 concurrent_mark()->abort();
1353
1354 // Make sure we'll choose a new allocation region afterwards.
1355 release_mutator_alloc_region();
1356 abandon_gc_alloc_regions();
1357 g1_rem_set()->cleanupHRRS();
1358
1359 // We should call this after we retire any currently active alloc
1360 // regions so that all the ALLOC / RETIRE events are generated
1361 // before the start GC event.
1362 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1363
1364 // We may have added regions to the current incremental collection
1365 // set between the last GC or pause and now. We need to clear the
1366 // incremental collection set and then start rebuilding it afresh
1367 // after this full GC.
1368 abandon_collection_set(g1_policy()->inc_cset_head());
1369 g1_policy()->clear_incremental_cset();
1370 g1_policy()->stop_incremental_cset_building();
1371
1372 tear_down_region_sets(false /* free_list_only */);
1373 g1_policy()->set_gcs_are_young(true);
1374
1375 // See the comments in g1CollectedHeap.hpp and
1376 // G1CollectedHeap::ref_processing_init() about
1377 // how reference processing currently works in G1.
1378
1379 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1380 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1381
1382 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1383 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1384
1385 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1386 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1387
1388 // Do collection work
1389 {
1390 HandleMark hm; // Discard invalid handles created during gc
1391 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1392 }
1393
1394 assert(free_regions() == 0, "we should not have added any free regions");
1395 rebuild_region_sets(false /* free_list_only */);
1396
1397 // Enqueue any discovered reference objects that have
1398 // not been removed from the discovered lists.
1399 ref_processor_stw()->enqueue_discovered_references();
1400
1401 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1402
1403 MemoryService::track_memory_usage();
1404
1405 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1406 ref_processor_stw()->verify_no_references_recorded();
1407
1408 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1409 ClassLoaderDataGraph::purge();
1410 MetaspaceAux::verify_metrics();
1411
1412 // Note: since we've just done a full GC, concurrent
1413 // marking is no longer active. Therefore we need not
1414 // re-enable reference discovery for the CM ref processor.
1415 // That will be done at the start of the next marking cycle.
1416 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1417 ref_processor_cm()->verify_no_references_recorded();
1418
1419 reset_gc_time_stamp();
1420 // Since everything potentially moved, we will clear all remembered
1421 // sets, and clear all cards. Later we will rebuild remembered
1422 // sets. We will also reset the GC time stamps of the regions.
1423 clear_rsets_post_compaction();
1424 check_gc_time_stamps();
1425
1426 // Resize the heap if necessary.
1427 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1428
1429 if (_hr_printer.is_active()) {
1430 // We should do this after we potentially resize the heap so
1431 // that all the COMMIT / UNCOMMIT events are generated before
1432 // the end GC event.
1433
1434 print_hrs_post_compaction();
1435 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1436 }
1437
1438 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1439 if (hot_card_cache->use_cache()) {
1440 hot_card_cache->reset_card_counts();
1441 hot_card_cache->reset_hot_cache();
1442 }
1443
1444 // Rebuild remembered sets of all regions.
1445 if (G1CollectedHeap::use_parallel_gc_threads()) {
1446 uint n_workers =
1447 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1448 workers()->active_workers(),
1449 Threads::number_of_non_daemon_threads());
1450 assert(UseDynamicNumberOfGCThreads ||
1451 n_workers == workers()->total_workers(),
1452 "If not dynamic should be using all the workers");
1453 workers()->set_active_workers(n_workers);
1454 // Set parallel threads in the heap (_n_par_threads) only
1455 // before a parallel phase and always reset it to 0 after
1456 // the phase so that the number of parallel threads does
1457 // no get carried forward to a serial phase where there
1458 // may be code that is "possibly_parallel".
1459 set_par_threads(n_workers);
1460
1461 ParRebuildRSTask rebuild_rs_task(this);
1462 assert(check_heap_region_claim_values(
1463 HeapRegion::InitialClaimValue), "sanity check");
1464 assert(UseDynamicNumberOfGCThreads ||
1465 workers()->active_workers() == workers()->total_workers(),
1466 "Unless dynamic should use total workers");
1467 // Use the most recent number of active workers
1468 assert(workers()->active_workers() > 0,
1469 "Active workers not properly set");
1470 set_par_threads(workers()->active_workers());
1471 workers()->run_task(&rebuild_rs_task);
1472 set_par_threads(0);
1473 assert(check_heap_region_claim_values(
1474 HeapRegion::RebuildRSClaimValue), "sanity check");
1475 reset_heap_region_claim_values();
1476 } else {
1477 RebuildRSOutOfRegionClosure rebuild_rs(this);
1478 heap_region_iterate(&rebuild_rs);
1479 }
1480
1481 // Rebuild the strong code root lists for each region
1482 rebuild_strong_code_roots();
1483
1484 if (true) { // FIXME
1485 MetaspaceGC::compute_new_size();
1486 }
1487
1488 #ifdef TRACESPINNING
1489 ParallelTaskTerminator::print_termination_counts();
1490 #endif
1491
1492 // Discard all rset updates
1493 JavaThread::dirty_card_queue_set().abandon_logs();
1494 assert(!G1DeferredRSUpdate
1495 || (G1DeferredRSUpdate &&
1496 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1497
1498 _young_list->reset_sampled_info();
1499 // At this point there should be no regions in the
1500 // entire heap tagged as young.
1501 assert(check_young_list_empty(true /* check_heap */),
1502 "young list should be empty at this point");
1503
1504 // Update the number of full collections that have been completed.
1505 increment_old_marking_cycles_completed(false /* concurrent */);
1506
1507 _hrs.verify_optional();
1508 verify_region_sets_optional();
1509
1510 verify_after_gc();
1511
1512 // Clear the previous marking bitmap, if needed for bitmap verification.
1513 // Note we cannot do this when we clear the next marking bitmap in
1514 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1515 // objects marked during a full GC against the previous bitmap.
1516 // But we need to clear it before calling check_bitmaps below since
1517 // the full GC has compacted objects and updated TAMS but not updated
1518 // the prev bitmap.
1519 if (G1VerifyBitmaps) {
1520 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1521 }
1522 check_bitmaps("Full GC End");
1523
1524 // Start a new incremental collection set for the next pause
1525 assert(g1_policy()->collection_set() == NULL, "must be");
1526 g1_policy()->start_incremental_cset_building();
1527
1528 clear_cset_fast_test();
1529
1530 init_mutator_alloc_region();
1531
1532 double end = os::elapsedTime();
1533 g1_policy()->record_full_collection_end();
1534
1535 if (G1Log::fine()) {
1536 g1_policy()->print_heap_transition();
1537 }
1538
1539 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1540 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1541 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1542 // before any GC notifications are raised.
1543 g1mm()->update_sizes();
1544
1545 gc_epilogue(true);
1546 }
1547
1548 if (G1Log::finer()) {
1549 g1_policy()->print_detailed_heap_transition(true /* full */);
1550 }
1551
1552 print_heap_after_gc();
1553 trace_heap_after_gc(gc_tracer);
1554
1555 post_full_gc_dump(gc_timer);
1556
1557 gc_timer->register_gc_end();
1558 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1559 }
1560
1561 return true;
1562 }
1563
1564 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1565 // do_collection() will return whether it succeeded in performing
1566 // the GC. Currently, there is no facility on the
1567 // do_full_collection() API to notify the caller than the collection
1568 // did not succeed (e.g., because it was locked out by the GC
1569 // locker). So, right now, we'll ignore the return value.
1570 bool dummy = do_collection(true, /* explicit_gc */
1571 clear_all_soft_refs,
1572 0 /* word_size */);
1573 }
1574
1575 // This code is mostly copied from TenuredGeneration.
1576 void
1577 G1CollectedHeap::
1578 resize_if_necessary_after_full_collection(size_t word_size) {
1579 // Include the current allocation, if any, and bytes that will be
1580 // pre-allocated to support collections, as "used".
1581 const size_t used_after_gc = used();
1582 const size_t capacity_after_gc = capacity();
1583 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1584
1585 // This is enforced in arguments.cpp.
1586 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1587 "otherwise the code below doesn't make sense");
1588
1589 // We don't have floating point command-line arguments
1590 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1591 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1592 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1593 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1594
1595 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1596 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1597
1598 // We have to be careful here as these two calculations can overflow
1599 // 32-bit size_t's.
1600 double used_after_gc_d = (double) used_after_gc;
1601 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1602 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1603
1604 // Let's make sure that they are both under the max heap size, which
1605 // by default will make them fit into a size_t.
1606 double desired_capacity_upper_bound = (double) max_heap_size;
1607 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1608 desired_capacity_upper_bound);
1609 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1610 desired_capacity_upper_bound);
1611
1612 // We can now safely turn them into size_t's.
1613 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1614 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1615
1616 // This assert only makes sense here, before we adjust them
1617 // with respect to the min and max heap size.
1618 assert(minimum_desired_capacity <= maximum_desired_capacity,
1619 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1620 "maximum_desired_capacity = "SIZE_FORMAT,
1621 minimum_desired_capacity, maximum_desired_capacity));
1622
1623 // Should not be greater than the heap max size. No need to adjust
1624 // it with respect to the heap min size as it's a lower bound (i.e.,
1625 // we'll try to make the capacity larger than it, not smaller).
1626 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1627 // Should not be less than the heap min size. No need to adjust it
1628 // with respect to the heap max size as it's an upper bound (i.e.,
1629 // we'll try to make the capacity smaller than it, not greater).
1630 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1631
1632 if (capacity_after_gc < minimum_desired_capacity) {
1633 // Don't expand unless it's significant
1634 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1635 ergo_verbose4(ErgoHeapSizing,
1636 "attempt heap expansion",
1637 ergo_format_reason("capacity lower than "
1638 "min desired capacity after Full GC")
1639 ergo_format_byte("capacity")
1640 ergo_format_byte("occupancy")
1641 ergo_format_byte_perc("min desired capacity"),
1642 capacity_after_gc, used_after_gc,
1643 minimum_desired_capacity, (double) MinHeapFreeRatio);
1644 expand(expand_bytes);
1645
1646 // No expansion, now see if we want to shrink
1647 } else if (capacity_after_gc > maximum_desired_capacity) {
1648 // Capacity too large, compute shrinking size
1649 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1650 ergo_verbose4(ErgoHeapSizing,
1651 "attempt heap shrinking",
1652 ergo_format_reason("capacity higher than "
1653 "max desired capacity after Full GC")
1654 ergo_format_byte("capacity")
1655 ergo_format_byte("occupancy")
1656 ergo_format_byte_perc("max desired capacity"),
1657 capacity_after_gc, used_after_gc,
1658 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1659 shrink(shrink_bytes);
1660 }
1661 }
1662
1663
1664 HeapWord*
1665 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1666 bool* succeeded) {
1667 assert_at_safepoint(true /* should_be_vm_thread */);
1668
1669 *succeeded = true;
1670 // Let's attempt the allocation first.
1671 HeapWord* result =
1672 attempt_allocation_at_safepoint(word_size,
1673 false /* expect_null_mutator_alloc_region */);
1674 if (result != NULL) {
1675 assert(*succeeded, "sanity");
1676 return result;
1677 }
1678
1679 // In a G1 heap, we're supposed to keep allocation from failing by
1680 // incremental pauses. Therefore, at least for now, we'll favor
1681 // expansion over collection. (This might change in the future if we can
1682 // do something smarter than full collection to satisfy a failed alloc.)
1683 result = expand_and_allocate(word_size);
1684 if (result != NULL) {
1685 assert(*succeeded, "sanity");
1686 return result;
1687 }
1688
1689 // Expansion didn't work, we'll try to do a Full GC.
1690 bool gc_succeeded = do_collection(false, /* explicit_gc */
1691 false, /* clear_all_soft_refs */
1692 word_size);
1693 if (!gc_succeeded) {
1694 *succeeded = false;
1695 return NULL;
1696 }
1697
1698 // Retry the allocation
1699 result = attempt_allocation_at_safepoint(word_size,
1700 true /* expect_null_mutator_alloc_region */);
1701 if (result != NULL) {
1702 assert(*succeeded, "sanity");
1703 return result;
1704 }
1705
1706 // Then, try a Full GC that will collect all soft references.
1707 gc_succeeded = do_collection(false, /* explicit_gc */
1708 true, /* clear_all_soft_refs */
1709 word_size);
1710 if (!gc_succeeded) {
1711 *succeeded = false;
1712 return NULL;
1713 }
1714
1715 // Retry the allocation once more
1716 result = attempt_allocation_at_safepoint(word_size,
1717 true /* expect_null_mutator_alloc_region */);
1718 if (result != NULL) {
1719 assert(*succeeded, "sanity");
1720 return result;
1721 }
1722
1723 assert(!collector_policy()->should_clear_all_soft_refs(),
1724 "Flag should have been handled and cleared prior to this point");
1725
1726 // What else? We might try synchronous finalization later. If the total
1727 // space available is large enough for the allocation, then a more
1728 // complete compaction phase than we've tried so far might be
1729 // appropriate.
1730 assert(*succeeded, "sanity");
1731 return NULL;
1732 }
1733
1734 // Attempting to expand the heap sufficiently
1735 // to support an allocation of the given "word_size". If
1736 // successful, perform the allocation and return the address of the
1737 // allocated block, or else "NULL".
1738
1739 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1740 assert_at_safepoint(true /* should_be_vm_thread */);
1741
1742 verify_region_sets_optional();
1743
1744 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1745 ergo_verbose1(ErgoHeapSizing,
1746 "attempt heap expansion",
1747 ergo_format_reason("allocation request failed")
1748 ergo_format_byte("allocation request"),
1749 word_size * HeapWordSize);
1750 if (expand(expand_bytes)) {
1751 _hrs.verify_optional();
1752 verify_region_sets_optional();
1753 return attempt_allocation_at_safepoint(word_size,
1754 false /* expect_null_mutator_alloc_region */);
1755 }
1756 return NULL;
1757 }
1758
1759 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1760 HeapWord* new_end) {
1761 assert(old_end != new_end, "don't call this otherwise");
1762 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1763
1764 // Update the committed mem region.
1765 _g1_committed.set_end(new_end);
1766 // Tell the card table about the update.
1767 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1768 // Tell the BOT about the update.
1769 _bot_shared->resize(_g1_committed.word_size());
1770 // Tell the hot card cache about the update
1771 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1772 }
1773
1774 bool G1CollectedHeap::expand(size_t expand_bytes) {
1775 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1776 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1777 HeapRegion::GrainBytes);
1778 ergo_verbose2(ErgoHeapSizing,
1779 "expand the heap",
1780 ergo_format_byte("requested expansion amount")
1781 ergo_format_byte("attempted expansion amount"),
1782 expand_bytes, aligned_expand_bytes);
1783
1784 if (_g1_storage.uncommitted_size() == 0) {
1785 ergo_verbose0(ErgoHeapSizing,
1786 "did not expand the heap",
1787 ergo_format_reason("heap already fully expanded"));
1788 return false;
1789 }
1790
1791 // First commit the memory.
1792 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1793 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1794 if (successful) {
1795 // Then propagate this update to the necessary data structures.
1796 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1797 update_committed_space(old_end, new_end);
1798
1799 FreeRegionList expansion_list("Local Expansion List");
1800 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1801 assert(mr.start() == old_end, "post-condition");
1802 // mr might be a smaller region than what was requested if
1803 // expand_by() was unable to allocate the HeapRegion instances
1804 assert(mr.end() <= new_end, "post-condition");
1805
1806 size_t actual_expand_bytes = mr.byte_size();
1807 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1808 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1809 "post-condition");
1810 if (actual_expand_bytes < aligned_expand_bytes) {
1811 // We could not expand _hrs to the desired size. In this case we
1812 // need to shrink the committed space accordingly.
1813 assert(mr.end() < new_end, "invariant");
1814
1815 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1816 // First uncommit the memory.
1817 _g1_storage.shrink_by(diff_bytes);
1818 // Then propagate this update to the necessary data structures.
1819 update_committed_space(new_end, mr.end());
1820 }
1821 _free_list.add_as_tail(&expansion_list);
1822
1823 if (_hr_printer.is_active()) {
1824 HeapWord* curr = mr.start();
1825 while (curr < mr.end()) {
1826 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1827 _hr_printer.commit(curr, curr_end);
1828 curr = curr_end;
1829 }
1830 assert(curr == mr.end(), "post-condition");
1831 }
1832 g1_policy()->record_new_heap_size(n_regions());
1833 } else {
1834 ergo_verbose0(ErgoHeapSizing,
1835 "did not expand the heap",
1836 ergo_format_reason("heap expansion operation failed"));
1837 // The expansion of the virtual storage space was unsuccessful.
1838 // Let's see if it was because we ran out of swap.
1839 if (G1ExitOnExpansionFailure &&
1840 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1841 // We had head room...
1842 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1843 }
1844 }
1845 return successful;
1846 }
1847
1848 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1849 size_t aligned_shrink_bytes =
1850 ReservedSpace::page_align_size_down(shrink_bytes);
1851 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1852 HeapRegion::GrainBytes);
1853 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1854
1855 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1856 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1857 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1858
1859 ergo_verbose3(ErgoHeapSizing,
1860 "shrink the heap",
1861 ergo_format_byte("requested shrinking amount")
1862 ergo_format_byte("aligned shrinking amount")
1863 ergo_format_byte("attempted shrinking amount"),
1864 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1865 if (num_regions_removed > 0) {
1866 _g1_storage.shrink_by(shrunk_bytes);
1867 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1868
1869 if (_hr_printer.is_active()) {
1870 HeapWord* curr = old_end;
1871 while (curr > new_end) {
1872 HeapWord* curr_end = curr;
1873 curr -= HeapRegion::GrainWords;
1874 _hr_printer.uncommit(curr, curr_end);
1875 }
1876 }
1877
1878 _expansion_regions += num_regions_removed;
1879 update_committed_space(old_end, new_end);
1880 HeapRegionRemSet::shrink_heap(n_regions());
1881 g1_policy()->record_new_heap_size(n_regions());
1882 } else {
1883 ergo_verbose0(ErgoHeapSizing,
1884 "did not shrink the heap",
1885 ergo_format_reason("heap shrinking operation failed"));
1886 }
1887 }
1888
1889 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1890 verify_region_sets_optional();
1891
1892 // We should only reach here at the end of a Full GC which means we
1893 // should not not be holding to any GC alloc regions. The method
1894 // below will make sure of that and do any remaining clean up.
1895 abandon_gc_alloc_regions();
1896
1897 // Instead of tearing down / rebuilding the free lists here, we
1898 // could instead use the remove_all_pending() method on free_list to
1899 // remove only the ones that we need to remove.
1900 tear_down_region_sets(true /* free_list_only */);
1901 shrink_helper(shrink_bytes);
1902 rebuild_region_sets(true /* free_list_only */);
1903
1904 _hrs.verify_optional();
1905 verify_region_sets_optional();
1906 }
1907
1908 // Public methods.
1909
1910 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1911 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1912 #endif // _MSC_VER
1913
1914
1915 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1916 SharedHeap(policy_),
1917 _g1_policy(policy_),
1918 _dirty_card_queue_set(false),
1919 _into_cset_dirty_card_queue_set(false),
1920 _is_alive_closure_cm(this),
1921 _is_alive_closure_stw(this),
1922 _ref_processor_cm(NULL),
1923 _ref_processor_stw(NULL),
1924 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1925 _bot_shared(NULL),
1926 _evac_failure_scan_stack(NULL),
1927 _mark_in_progress(false),
1928 _cg1r(NULL), _summary_bytes_used(0),
1929 _g1mm(NULL),
1930 _refine_cte_cl(NULL),
1931 _full_collection(false),
1932 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1933 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1934 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1935 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1936 _free_regions_coming(false),
1937 _young_list(new YoungList(this)),
1938 _gc_time_stamp(0),
1939 _retained_old_gc_alloc_region(NULL),
1940 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1941 _old_plab_stats(OldPLABSize, PLABWeight),
1942 _expand_heap_after_alloc_failure(true),
1943 _surviving_young_words(NULL),
1944 _old_marking_cycles_started(0),
1945 _old_marking_cycles_completed(0),
1946 _concurrent_cycle_started(false),
1947 _in_cset_fast_test(),
1948 _dirty_cards_region_list(NULL),
1949 _worker_cset_start_region(NULL),
1950 _worker_cset_start_region_time_stamp(NULL),
1951 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1952 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1953 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1954 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1955
1956 _g1h = this;
1957 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1958 vm_exit_during_initialization("Failed necessary allocation.");
1959 }
1960
1961 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1962
1963 int n_queues = MAX2((int)ParallelGCThreads, 1);
1964 _task_queues = new RefToScanQueueSet(n_queues);
1965
1966 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1967 assert(n_rem_sets > 0, "Invariant.");
1968
1969 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1970 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1971 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1972
1973 for (int i = 0; i < n_queues; i++) {
1974 RefToScanQueue* q = new RefToScanQueue();
1975 q->initialize();
1976 _task_queues->register_queue(i, q);
1977 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1978 }
1979 clear_cset_start_regions();
1980
1981 // Initialize the G1EvacuationFailureALot counters and flags.
1982 NOT_PRODUCT(reset_evacuation_should_fail();)
1983
1984 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1985 }
1986
1987 jint G1CollectedHeap::initialize() {
1988 CollectedHeap::pre_initialize();
1989 os::enable_vtime();
1990
1991 G1Log::init();
1992
1993 // Necessary to satisfy locking discipline assertions.
1994
1995 MutexLocker x(Heap_lock);
1996
1997 // We have to initialize the printer before committing the heap, as
1998 // it will be used then.
1999 _hr_printer.set_active(G1PrintHeapRegions);
2000
2001 // While there are no constraints in the GC code that HeapWordSize
2002 // be any particular value, there are multiple other areas in the
2003 // system which believe this to be true (e.g. oop->object_size in some
2004 // cases incorrectly returns the size in wordSize units rather than
2005 // HeapWordSize).
2006 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2007
2008 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2009 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2010 size_t heap_alignment = collector_policy()->heap_alignment();
2011
2012 // Ensure that the sizes are properly aligned.
2013 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2014 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2015 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2016
2017 _refine_cte_cl = new RefineCardTableEntryClosure();
2018
2019 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2020
2021 // Reserve the maximum.
2022
2023 // When compressed oops are enabled, the preferred heap base
2024 // is calculated by subtracting the requested size from the
2025 // 32Gb boundary and using the result as the base address for
2026 // heap reservation. If the requested size is not aligned to
2027 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2028 // into the ReservedHeapSpace constructor) then the actual
2029 // base of the reserved heap may end up differing from the
2030 // address that was requested (i.e. the preferred heap base).
2031 // If this happens then we could end up using a non-optimal
2032 // compressed oops mode.
2033
2034 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2035 heap_alignment);
2036
2037 // It is important to do this in a way such that concurrent readers can't
2038 // temporarily think something is in the heap. (I've actually seen this
2039 // happen in asserts: DLD.)
2040 _reserved.set_word_size(0);
2041 _reserved.set_start((HeapWord*)heap_rs.base());
2042 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2043
2044 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2045
2046 // Create the gen rem set (and barrier set) for the entire reserved region.
2047 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2048 set_barrier_set(rem_set()->bs());
2049 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2050 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2051 return JNI_ENOMEM;
2052 }
2053
2054 // Also create a G1 rem set.
2055 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2056
2057 // Carve out the G1 part of the heap.
2058
2059 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2060 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2061 g1_rs.size()/HeapWordSize);
2062
2063 _g1_storage.initialize(g1_rs, 0);
2064 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2065 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2066 (HeapWord*) _g1_reserved.end());
2067 assert(_hrs.max_length() == _expansion_regions,
2068 err_msg("max length: %u expansion regions: %u",
2069 _hrs.max_length(), _expansion_regions));
2070
2071 // Do later initialization work for concurrent refinement.
2072 _cg1r->init();
2073
2074 // 6843694 - ensure that the maximum region index can fit
2075 // in the remembered set structures.
2076 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2077 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2078
2079 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2080 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2081 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2082 "too many cards per region");
2083
2084 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2085
2086 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2087 heap_word_size(init_byte_size));
2088
2089 _g1h = this;
2090
2091 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2092
2093 // Create the ConcurrentMark data structure and thread.
2094 // (Must do this late, so that "max_regions" is defined.)
2095 _cm = new ConcurrentMark(this, heap_rs);
2096 if (_cm == NULL || !_cm->completed_initialization()) {
2097 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2098 return JNI_ENOMEM;
2099 }
2100 _cmThread = _cm->cmThread();
2101
2102 // Initialize the from_card cache structure of HeapRegionRemSet.
2103 HeapRegionRemSet::init_heap(max_regions());
2104
2105 // Now expand into the initial heap size.
2106 if (!expand(init_byte_size)) {
2107 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2108 return JNI_ENOMEM;
2109 }
2110
2111 // Perform any initialization actions delegated to the policy.
2112 g1_policy()->init();
2113
2114 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2115 SATB_Q_FL_lock,
2116 G1SATBProcessCompletedThreshold,
2117 Shared_SATB_Q_lock);
2118
2119 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2120 DirtyCardQ_CBL_mon,
2121 DirtyCardQ_FL_lock,
2122 concurrent_g1_refine()->yellow_zone(),
2123 concurrent_g1_refine()->red_zone(),
2124 Shared_DirtyCardQ_lock);
2125
2126 if (G1DeferredRSUpdate) {
2127 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2128 DirtyCardQ_CBL_mon,
2129 DirtyCardQ_FL_lock,
2130 -1, // never trigger processing
2131 -1, // no limit on length
2132 Shared_DirtyCardQ_lock,
2133 &JavaThread::dirty_card_queue_set());
2134 }
2135
2136 // Initialize the card queue set used to hold cards containing
2137 // references into the collection set.
2138 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2139 DirtyCardQ_CBL_mon,
2140 DirtyCardQ_FL_lock,
2141 -1, // never trigger processing
2142 -1, // no limit on length
2143 Shared_DirtyCardQ_lock,
2144 &JavaThread::dirty_card_queue_set());
2145
2146 // In case we're keeping closure specialization stats, initialize those
2147 // counts and that mechanism.
2148 SpecializationStats::clear();
2149
2150 // Here we allocate the dummy full region that is required by the
2151 // G1AllocRegion class. If we don't pass an address in the reserved
2152 // space here, lots of asserts fire.
2153
2154 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2155 _g1_reserved.start());
2156 // We'll re-use the same region whether the alloc region will
2157 // require BOT updates or not and, if it doesn't, then a non-young
2158 // region will complain that it cannot support allocations without
2159 // BOT updates. So we'll tag the dummy region as young to avoid that.
2160 dummy_region->set_young();
2161 // Make sure it's full.
2162 dummy_region->set_top(dummy_region->end());
2163 G1AllocRegion::setup(this, dummy_region);
2164
2165 init_mutator_alloc_region();
2166
2167 // Do create of the monitoring and management support so that
2168 // values in the heap have been properly initialized.
2169 _g1mm = new G1MonitoringSupport(this);
2170
2171 G1StringDedup::initialize();
2172
2173 return JNI_OK;
2174 }
2175
2176 void G1CollectedHeap::stop() {
2177 #if 0
2178 // Stopping concurrent worker threads is currently disabled until
2179 // some bugs in concurrent mark has been resolve. Without fixing
2180 // those bugs first we risk haning during VM exit when trying to
2181 // stop these threads.
2182
2183 // Abort any ongoing concurrent root region scanning and stop all
2184 // concurrent threads. We do this to make sure these threads do
2185 // not continue to execute and access resources (e.g. gclog_or_tty)
2186 // that are destroyed during shutdown.
2187 _cm->root_regions()->abort();
2188 _cm->root_regions()->wait_until_scan_finished();
2189 stop_conc_gc_threads();
2190 #endif
2191 }
2192
2193 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2194 return HeapRegion::max_region_size();
2195 }
2196
2197 void G1CollectedHeap::ref_processing_init() {
2198 // Reference processing in G1 currently works as follows:
2199 //
2200 // * There are two reference processor instances. One is
2201 // used to record and process discovered references
2202 // during concurrent marking; the other is used to
2203 // record and process references during STW pauses
2204 // (both full and incremental).
2205 // * Both ref processors need to 'span' the entire heap as
2206 // the regions in the collection set may be dotted around.
2207 //
2208 // * For the concurrent marking ref processor:
2209 // * Reference discovery is enabled at initial marking.
2210 // * Reference discovery is disabled and the discovered
2211 // references processed etc during remarking.
2212 // * Reference discovery is MT (see below).
2213 // * Reference discovery requires a barrier (see below).
2214 // * Reference processing may or may not be MT
2215 // (depending on the value of ParallelRefProcEnabled
2216 // and ParallelGCThreads).
2217 // * A full GC disables reference discovery by the CM
2218 // ref processor and abandons any entries on it's
2219 // discovered lists.
2220 //
2221 // * For the STW processor:
2222 // * Non MT discovery is enabled at the start of a full GC.
2223 // * Processing and enqueueing during a full GC is non-MT.
2224 // * During a full GC, references are processed after marking.
2225 //
2226 // * Discovery (may or may not be MT) is enabled at the start
2227 // of an incremental evacuation pause.
2228 // * References are processed near the end of a STW evacuation pause.
2229 // * For both types of GC:
2230 // * Discovery is atomic - i.e. not concurrent.
2231 // * Reference discovery will not need a barrier.
2232
2233 SharedHeap::ref_processing_init();
2234 MemRegion mr = reserved_region();
2235
2236 // Concurrent Mark ref processor
2237 _ref_processor_cm =
2238 new ReferenceProcessor(mr, // span
2239 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2240 // mt processing
2241 (int) ParallelGCThreads,
2242 // degree of mt processing
2243 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2244 // mt discovery
2245 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2246 // degree of mt discovery
2247 false,
2248 // Reference discovery is not atomic
2249 &_is_alive_closure_cm,
2250 // is alive closure
2251 // (for efficiency/performance)
2252 true);
2253 // Setting next fields of discovered
2254 // lists requires a barrier.
2255
2256 // STW ref processor
2257 _ref_processor_stw =
2258 new ReferenceProcessor(mr, // span
2259 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2260 // mt processing
2261 MAX2((int)ParallelGCThreads, 1),
2262 // degree of mt processing
2263 (ParallelGCThreads > 1),
2264 // mt discovery
2265 MAX2((int)ParallelGCThreads, 1),
2266 // degree of mt discovery
2267 true,
2268 // Reference discovery is atomic
2269 &_is_alive_closure_stw,
2270 // is alive closure
2271 // (for efficiency/performance)
2272 false);
2273 // Setting next fields of discovered
2274 // lists does not require a barrier.
2275 }
2276
2277 size_t G1CollectedHeap::capacity() const {
2278 return _g1_committed.byte_size();
2279 }
2280
2281 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2282 assert(!hr->continuesHumongous(), "pre-condition");
2283 hr->reset_gc_time_stamp();
2284 if (hr->startsHumongous()) {
2285 uint first_index = hr->hrs_index() + 1;
2286 uint last_index = hr->last_hc_index();
2287 for (uint i = first_index; i < last_index; i += 1) {
2288 HeapRegion* chr = region_at(i);
2289 assert(chr->continuesHumongous(), "sanity");
2290 chr->reset_gc_time_stamp();
2291 }
2292 }
2293 }
2294
2295 #ifndef PRODUCT
2296 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2297 private:
2298 unsigned _gc_time_stamp;
2299 bool _failures;
2300
2301 public:
2302 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2303 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2304
2305 virtual bool doHeapRegion(HeapRegion* hr) {
2306 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2307 if (_gc_time_stamp != region_gc_time_stamp) {
2308 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2309 "expected %d", HR_FORMAT_PARAMS(hr),
2310 region_gc_time_stamp, _gc_time_stamp);
2311 _failures = true;
2312 }
2313 return false;
2314 }
2315
2316 bool failures() { return _failures; }
2317 };
2318
2319 void G1CollectedHeap::check_gc_time_stamps() {
2320 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2321 heap_region_iterate(&cl);
2322 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2323 }
2324 #endif // PRODUCT
2325
2326 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2327 DirtyCardQueue* into_cset_dcq,
2328 bool concurrent,
2329 uint worker_i) {
2330 // Clean cards in the hot card cache
2331 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2332 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2333
2334 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2335 int n_completed_buffers = 0;
2336 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2337 n_completed_buffers++;
2338 }
2339 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2340 dcqs.clear_n_completed_buffers();
2341 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2342 }
2343
2344
2345 // Computes the sum of the storage used by the various regions.
2346
2347 size_t G1CollectedHeap::used() const {
2348 assert(Heap_lock->owner() != NULL,
2349 "Should be owned on this thread's behalf.");
2350 size_t result = _summary_bytes_used;
2351 // Read only once in case it is set to NULL concurrently
2352 HeapRegion* hr = _mutator_alloc_region.get();
2353 if (hr != NULL)
2354 result += hr->used();
2355 return result;
2356 }
2357
2358 size_t G1CollectedHeap::used_unlocked() const {
2359 size_t result = _summary_bytes_used;
2360 return result;
2361 }
2362
2363 class SumUsedClosure: public HeapRegionClosure {
2364 size_t _used;
2365 public:
2366 SumUsedClosure() : _used(0) {}
2367 bool doHeapRegion(HeapRegion* r) {
2368 if (!r->continuesHumongous()) {
2369 _used += r->used();
2370 }
2371 return false;
2372 }
2373 size_t result() { return _used; }
2374 };
2375
2376 size_t G1CollectedHeap::recalculate_used() const {
2377 double recalculate_used_start = os::elapsedTime();
2378
2379 SumUsedClosure blk;
2380 heap_region_iterate(&blk);
2381
2382 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2383 return blk.result();
2384 }
2385
2386 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2387 switch (cause) {
2388 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2389 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2390 case GCCause::_g1_humongous_allocation: return true;
2391 default: return false;
2392 }
2393 }
2394
2395 #ifndef PRODUCT
2396 void G1CollectedHeap::allocate_dummy_regions() {
2397 // Let's fill up most of the region
2398 size_t word_size = HeapRegion::GrainWords - 1024;
2399 // And as a result the region we'll allocate will be humongous.
2400 guarantee(isHumongous(word_size), "sanity");
2401
2402 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2403 // Let's use the existing mechanism for the allocation
2404 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2405 if (dummy_obj != NULL) {
2406 MemRegion mr(dummy_obj, word_size);
2407 CollectedHeap::fill_with_object(mr);
2408 } else {
2409 // If we can't allocate once, we probably cannot allocate
2410 // again. Let's get out of the loop.
2411 break;
2412 }
2413 }
2414 }
2415 #endif // !PRODUCT
2416
2417 void G1CollectedHeap::increment_old_marking_cycles_started() {
2418 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2419 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2420 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2421 _old_marking_cycles_started, _old_marking_cycles_completed));
2422
2423 _old_marking_cycles_started++;
2424 }
2425
2426 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2427 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2428
2429 // We assume that if concurrent == true, then the caller is a
2430 // concurrent thread that was joined the Suspendible Thread
2431 // Set. If there's ever a cheap way to check this, we should add an
2432 // assert here.
2433
2434 // Given that this method is called at the end of a Full GC or of a
2435 // concurrent cycle, and those can be nested (i.e., a Full GC can
2436 // interrupt a concurrent cycle), the number of full collections
2437 // completed should be either one (in the case where there was no
2438 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2439 // behind the number of full collections started.
2440
2441 // This is the case for the inner caller, i.e. a Full GC.
2442 assert(concurrent ||
2443 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2444 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2445 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2446 "is inconsistent with _old_marking_cycles_completed = %u",
2447 _old_marking_cycles_started, _old_marking_cycles_completed));
2448
2449 // This is the case for the outer caller, i.e. the concurrent cycle.
2450 assert(!concurrent ||
2451 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2452 err_msg("for outer caller (concurrent cycle): "
2453 "_old_marking_cycles_started = %u "
2454 "is inconsistent with _old_marking_cycles_completed = %u",
2455 _old_marking_cycles_started, _old_marking_cycles_completed));
2456
2457 _old_marking_cycles_completed += 1;
2458
2459 // We need to clear the "in_progress" flag in the CM thread before
2460 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2461 // is set) so that if a waiter requests another System.gc() it doesn't
2462 // incorrectly see that a marking cycle is still in progress.
2463 if (concurrent) {
2464 _cmThread->clear_in_progress();
2465 }
2466
2467 // This notify_all() will ensure that a thread that called
2468 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2469 // and it's waiting for a full GC to finish will be woken up. It is
2470 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2471 FullGCCount_lock->notify_all();
2472 }
2473
2474 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2475 _concurrent_cycle_started = true;
2476 _gc_timer_cm->register_gc_start(start_time);
2477
2478 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2479 trace_heap_before_gc(_gc_tracer_cm);
2480 }
2481
2482 void G1CollectedHeap::register_concurrent_cycle_end() {
2483 if (_concurrent_cycle_started) {
2484 if (_cm->has_aborted()) {
2485 _gc_tracer_cm->report_concurrent_mode_failure();
2486 }
2487
2488 _gc_timer_cm->register_gc_end();
2489 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2490
2491 _concurrent_cycle_started = false;
2492 }
2493 }
2494
2495 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2496 if (_concurrent_cycle_started) {
2497 trace_heap_after_gc(_gc_tracer_cm);
2498 }
2499 }
2500
2501 G1YCType G1CollectedHeap::yc_type() {
2502 bool is_young = g1_policy()->gcs_are_young();
2503 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2504 bool is_during_mark = mark_in_progress();
2505
2506 if (is_initial_mark) {
2507 return InitialMark;
2508 } else if (is_during_mark) {
2509 return DuringMark;
2510 } else if (is_young) {
2511 return Normal;
2512 } else {
2513 return Mixed;
2514 }
2515 }
2516
2517 void G1CollectedHeap::collect(GCCause::Cause cause) {
2518 assert_heap_not_locked();
2519
2520 unsigned int gc_count_before;
2521 unsigned int old_marking_count_before;
2522 bool retry_gc;
2523
2524 do {
2525 retry_gc = false;
2526
2527 {
2528 MutexLocker ml(Heap_lock);
2529
2530 // Read the GC count while holding the Heap_lock
2531 gc_count_before = total_collections();
2532 old_marking_count_before = _old_marking_cycles_started;
2533 }
2534
2535 if (should_do_concurrent_full_gc(cause)) {
2536 // Schedule an initial-mark evacuation pause that will start a
2537 // concurrent cycle. We're setting word_size to 0 which means that
2538 // we are not requesting a post-GC allocation.
2539 VM_G1IncCollectionPause op(gc_count_before,
2540 0, /* word_size */
2541 true, /* should_initiate_conc_mark */
2542 g1_policy()->max_pause_time_ms(),
2543 cause);
2544
2545 VMThread::execute(&op);
2546 if (!op.pause_succeeded()) {
2547 if (old_marking_count_before == _old_marking_cycles_started) {
2548 retry_gc = op.should_retry_gc();
2549 } else {
2550 // A Full GC happened while we were trying to schedule the
2551 // initial-mark GC. No point in starting a new cycle given
2552 // that the whole heap was collected anyway.
2553 }
2554
2555 if (retry_gc) {
2556 if (GC_locker::is_active_and_needs_gc()) {
2557 GC_locker::stall_until_clear();
2558 }
2559 }
2560 }
2561 } else {
2562 if (cause == GCCause::_gc_locker
2563 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2564
2565 // Schedule a standard evacuation pause. We're setting word_size
2566 // to 0 which means that we are not requesting a post-GC allocation.
2567 VM_G1IncCollectionPause op(gc_count_before,
2568 0, /* word_size */
2569 false, /* should_initiate_conc_mark */
2570 g1_policy()->max_pause_time_ms(),
2571 cause);
2572 VMThread::execute(&op);
2573 } else {
2574 // Schedule a Full GC.
2575 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2576 VMThread::execute(&op);
2577 }
2578 }
2579 } while (retry_gc);
2580 }
2581
2582 bool G1CollectedHeap::is_in(const void* p) const {
2583 if (_g1_committed.contains(p)) {
2584 // Given that we know that p is in the committed space,
2585 // heap_region_containing_raw() should successfully
2586 // return the containing region.
2587 HeapRegion* hr = heap_region_containing_raw(p);
2588 return hr->is_in(p);
2589 } else {
2590 return false;
2591 }
2592 }
2593
2594 // Iteration functions.
2595
2596 // Iterates an OopClosure over all ref-containing fields of objects
2597 // within a HeapRegion.
2598
2599 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2600 MemRegion _mr;
2601 ExtendedOopClosure* _cl;
2602 public:
2603 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2604 : _mr(mr), _cl(cl) {}
2605 bool doHeapRegion(HeapRegion* r) {
2606 if (!r->continuesHumongous()) {
2607 r->oop_iterate(_cl);
2608 }
2609 return false;
2610 }
2611 };
2612
2613 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2614 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2615 heap_region_iterate(&blk);
2616 }
2617
2618 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2619 IterateOopClosureRegionClosure blk(mr, cl);
2620 heap_region_iterate(&blk);
2621 }
2622
2623 // Iterates an ObjectClosure over all objects within a HeapRegion.
2624
2625 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2626 ObjectClosure* _cl;
2627 public:
2628 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2629 bool doHeapRegion(HeapRegion* r) {
2630 if (! r->continuesHumongous()) {
2631 r->object_iterate(_cl);
2632 }
2633 return false;
2634 }
2635 };
2636
2637 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2638 IterateObjectClosureRegionClosure blk(cl);
2639 heap_region_iterate(&blk);
2640 }
2641
2642 // Calls a SpaceClosure on a HeapRegion.
2643
2644 class SpaceClosureRegionClosure: public HeapRegionClosure {
2645 SpaceClosure* _cl;
2646 public:
2647 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2648 bool doHeapRegion(HeapRegion* r) {
2649 _cl->do_space(r);
2650 return false;
2651 }
2652 };
2653
2654 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2655 SpaceClosureRegionClosure blk(cl);
2656 heap_region_iterate(&blk);
2657 }
2658
2659 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2660 _hrs.iterate(cl);
2661 }
2662
2663 void
2664 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2665 uint worker_id,
2666 uint no_of_par_workers,
2667 jint claim_value) {
2668 const uint regions = n_regions();
2669 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2670 no_of_par_workers :
2671 1);
2672 assert(UseDynamicNumberOfGCThreads ||
2673 no_of_par_workers == workers()->total_workers(),
2674 "Non dynamic should use fixed number of workers");
2675 // try to spread out the starting points of the workers
2676 const HeapRegion* start_hr =
2677 start_region_for_worker(worker_id, no_of_par_workers);
2678 const uint start_index = start_hr->hrs_index();
2679
2680 // each worker will actually look at all regions
2681 for (uint count = 0; count < regions; ++count) {
2682 const uint index = (start_index + count) % regions;
2683 assert(0 <= index && index < regions, "sanity");
2684 HeapRegion* r = region_at(index);
2685 // we'll ignore "continues humongous" regions (we'll process them
2686 // when we come across their corresponding "start humongous"
2687 // region) and regions already claimed
2688 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2689 continue;
2690 }
2691 // OK, try to claim it
2692 if (r->claimHeapRegion(claim_value)) {
2693 // success!
2694 assert(!r->continuesHumongous(), "sanity");
2695 if (r->startsHumongous()) {
2696 // If the region is "starts humongous" we'll iterate over its
2697 // "continues humongous" first; in fact we'll do them
2698 // first. The order is important. In on case, calling the
2699 // closure on the "starts humongous" region might de-allocate
2700 // and clear all its "continues humongous" regions and, as a
2701 // result, we might end up processing them twice. So, we'll do
2702 // them first (notice: most closures will ignore them anyway) and
2703 // then we'll do the "starts humongous" region.
2704 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2705 HeapRegion* chr = region_at(ch_index);
2706
2707 // if the region has already been claimed or it's not
2708 // "continues humongous" we're done
2709 if (chr->claim_value() == claim_value ||
2710 !chr->continuesHumongous()) {
2711 break;
2712 }
2713
2714 // No one should have claimed it directly. We can given
2715 // that we claimed its "starts humongous" region.
2716 assert(chr->claim_value() != claim_value, "sanity");
2717 assert(chr->humongous_start_region() == r, "sanity");
2718
2719 if (chr->claimHeapRegion(claim_value)) {
2720 // we should always be able to claim it; no one else should
2721 // be trying to claim this region
2722
2723 bool res2 = cl->doHeapRegion(chr);
2724 assert(!res2, "Should not abort");
2725
2726 // Right now, this holds (i.e., no closure that actually
2727 // does something with "continues humongous" regions
2728 // clears them). We might have to weaken it in the future,
2729 // but let's leave these two asserts here for extra safety.
2730 assert(chr->continuesHumongous(), "should still be the case");
2731 assert(chr->humongous_start_region() == r, "sanity");
2732 } else {
2733 guarantee(false, "we should not reach here");
2734 }
2735 }
2736 }
2737
2738 assert(!r->continuesHumongous(), "sanity");
2739 bool res = cl->doHeapRegion(r);
2740 assert(!res, "Should not abort");
2741 }
2742 }
2743 }
2744
2745 class ResetClaimValuesClosure: public HeapRegionClosure {
2746 public:
2747 bool doHeapRegion(HeapRegion* r) {
2748 r->set_claim_value(HeapRegion::InitialClaimValue);
2749 return false;
2750 }
2751 };
2752
2753 void G1CollectedHeap::reset_heap_region_claim_values() {
2754 ResetClaimValuesClosure blk;
2755 heap_region_iterate(&blk);
2756 }
2757
2758 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2759 ResetClaimValuesClosure blk;
2760 collection_set_iterate(&blk);
2761 }
2762
2763 #ifdef ASSERT
2764 // This checks whether all regions in the heap have the correct claim
2765 // value. I also piggy-backed on this a check to ensure that the
2766 // humongous_start_region() information on "continues humongous"
2767 // regions is correct.
2768
2769 class CheckClaimValuesClosure : public HeapRegionClosure {
2770 private:
2771 jint _claim_value;
2772 uint _failures;
2773 HeapRegion* _sh_region;
2774
2775 public:
2776 CheckClaimValuesClosure(jint claim_value) :
2777 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2778 bool doHeapRegion(HeapRegion* r) {
2779 if (r->claim_value() != _claim_value) {
2780 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2781 "claim value = %d, should be %d",
2782 HR_FORMAT_PARAMS(r),
2783 r->claim_value(), _claim_value);
2784 ++_failures;
2785 }
2786 if (!r->isHumongous()) {
2787 _sh_region = NULL;
2788 } else if (r->startsHumongous()) {
2789 _sh_region = r;
2790 } else if (r->continuesHumongous()) {
2791 if (r->humongous_start_region() != _sh_region) {
2792 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2793 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2794 HR_FORMAT_PARAMS(r),
2795 r->humongous_start_region(),
2796 _sh_region);
2797 ++_failures;
2798 }
2799 }
2800 return false;
2801 }
2802 uint failures() { return _failures; }
2803 };
2804
2805 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2806 CheckClaimValuesClosure cl(claim_value);
2807 heap_region_iterate(&cl);
2808 return cl.failures() == 0;
2809 }
2810
2811 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2812 private:
2813 jint _claim_value;
2814 uint _failures;
2815
2816 public:
2817 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2818 _claim_value(claim_value), _failures(0) { }
2819
2820 uint failures() { return _failures; }
2821
2822 bool doHeapRegion(HeapRegion* hr) {
2823 assert(hr->in_collection_set(), "how?");
2824 assert(!hr->isHumongous(), "H-region in CSet");
2825 if (hr->claim_value() != _claim_value) {
2826 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2827 "claim value = %d, should be %d",
2828 HR_FORMAT_PARAMS(hr),
2829 hr->claim_value(), _claim_value);
2830 _failures += 1;
2831 }
2832 return false;
2833 }
2834 };
2835
2836 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2837 CheckClaimValuesInCSetHRClosure cl(claim_value);
2838 collection_set_iterate(&cl);
2839 return cl.failures() == 0;
2840 }
2841 #endif // ASSERT
2842
2843 // Clear the cached CSet starting regions and (more importantly)
2844 // the time stamps. Called when we reset the GC time stamp.
2845 void G1CollectedHeap::clear_cset_start_regions() {
2846 assert(_worker_cset_start_region != NULL, "sanity");
2847 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2848
2849 int n_queues = MAX2((int)ParallelGCThreads, 1);
2850 for (int i = 0; i < n_queues; i++) {
2851 _worker_cset_start_region[i] = NULL;
2852 _worker_cset_start_region_time_stamp[i] = 0;
2853 }
2854 }
2855
2856 // Given the id of a worker, obtain or calculate a suitable
2857 // starting region for iterating over the current collection set.
2858 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2859 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2860
2861 HeapRegion* result = NULL;
2862 unsigned gc_time_stamp = get_gc_time_stamp();
2863
2864 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2865 // Cached starting region for current worker was set
2866 // during the current pause - so it's valid.
2867 // Note: the cached starting heap region may be NULL
2868 // (when the collection set is empty).
2869 result = _worker_cset_start_region[worker_i];
2870 assert(result == NULL || result->in_collection_set(), "sanity");
2871 return result;
2872 }
2873
2874 // The cached entry was not valid so let's calculate
2875 // a suitable starting heap region for this worker.
2876
2877 // We want the parallel threads to start their collection
2878 // set iteration at different collection set regions to
2879 // avoid contention.
2880 // If we have:
2881 // n collection set regions
2882 // p threads
2883 // Then thread t will start at region floor ((t * n) / p)
2884
2885 result = g1_policy()->collection_set();
2886 if (G1CollectedHeap::use_parallel_gc_threads()) {
2887 uint cs_size = g1_policy()->cset_region_length();
2888 uint active_workers = workers()->active_workers();
2889 assert(UseDynamicNumberOfGCThreads ||
2890 active_workers == workers()->total_workers(),
2891 "Unless dynamic should use total workers");
2892
2893 uint end_ind = (cs_size * worker_i) / active_workers;
2894 uint start_ind = 0;
2895
2896 if (worker_i > 0 &&
2897 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2898 // Previous workers starting region is valid
2899 // so let's iterate from there
2900 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2901 result = _worker_cset_start_region[worker_i - 1];
2902 }
2903
2904 for (uint i = start_ind; i < end_ind; i++) {
2905 result = result->next_in_collection_set();
2906 }
2907 }
2908
2909 // Note: the calculated starting heap region may be NULL
2910 // (when the collection set is empty).
2911 assert(result == NULL || result->in_collection_set(), "sanity");
2912 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2913 "should be updated only once per pause");
2914 _worker_cset_start_region[worker_i] = result;
2915 OrderAccess::storestore();
2916 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2917 return result;
2918 }
2919
2920 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2921 uint no_of_par_workers) {
2922 uint worker_num =
2923 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2924 assert(UseDynamicNumberOfGCThreads ||
2925 no_of_par_workers == workers()->total_workers(),
2926 "Non dynamic should use fixed number of workers");
2927 const uint start_index = n_regions() * worker_i / worker_num;
2928 return region_at(start_index);
2929 }
2930
2931 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2932 HeapRegion* r = g1_policy()->collection_set();
2933 while (r != NULL) {
2934 HeapRegion* next = r->next_in_collection_set();
2935 if (cl->doHeapRegion(r)) {
2936 cl->incomplete();
2937 return;
2938 }
2939 r = next;
2940 }
2941 }
2942
2943 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2944 HeapRegionClosure *cl) {
2945 if (r == NULL) {
2946 // The CSet is empty so there's nothing to do.
2947 return;
2948 }
2949
2950 assert(r->in_collection_set(),
2951 "Start region must be a member of the collection set.");
2952 HeapRegion* cur = r;
2953 while (cur != NULL) {
2954 HeapRegion* next = cur->next_in_collection_set();
2955 if (cl->doHeapRegion(cur) && false) {
2956 cl->incomplete();
2957 return;
2958 }
2959 cur = next;
2960 }
2961 cur = g1_policy()->collection_set();
2962 while (cur != r) {
2963 HeapRegion* next = cur->next_in_collection_set();
2964 if (cl->doHeapRegion(cur) && false) {
2965 cl->incomplete();
2966 return;
2967 }
2968 cur = next;
2969 }
2970 }
2971
2972 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2973 return n_regions() > 0 ? region_at(0) : NULL;
2974 }
2975
2976
2977 Space* G1CollectedHeap::space_containing(const void* addr) const {
2978 return heap_region_containing(addr);
2979 }
2980
2981 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2982 Space* sp = space_containing(addr);
2983 return sp->block_start(addr);
2984 }
2985
2986 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2987 Space* sp = space_containing(addr);
2988 return sp->block_size(addr);
2989 }
2990
2991 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2992 Space* sp = space_containing(addr);
2993 return sp->block_is_obj(addr);
2994 }
2995
2996 bool G1CollectedHeap::supports_tlab_allocation() const {
2997 return true;
2998 }
2999
3000 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3001 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
3002 }
3003
3004 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3005 return young_list()->eden_used_bytes();
3006 }
3007
3008 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3009 // must be smaller than the humongous object limit.
3010 size_t G1CollectedHeap::max_tlab_size() const {
3011 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3012 }
3013
3014 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3015 // Return the remaining space in the cur alloc region, but not less than
3016 // the min TLAB size.
3017
3018 // Also, this value can be at most the humongous object threshold,
3019 // since we can't allow tlabs to grow big enough to accommodate
3020 // humongous objects.
3021
3022 HeapRegion* hr = _mutator_alloc_region.get();
3023 size_t max_tlab = max_tlab_size() * wordSize;
3024 if (hr == NULL) {
3025 return max_tlab;
3026 } else {
3027 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3028 }
3029 }
3030
3031 size_t G1CollectedHeap::max_capacity() const {
3032 return _g1_reserved.byte_size();
3033 }
3034
3035 jlong G1CollectedHeap::millis_since_last_gc() {
3036 // assert(false, "NYI");
3037 return 0;
3038 }
3039
3040 void G1CollectedHeap::prepare_for_verify() {
3041 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3042 ensure_parsability(false);
3043 }
3044 g1_rem_set()->prepare_for_verify();
3045 }
3046
3047 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3048 VerifyOption vo) {
3049 switch (vo) {
3050 case VerifyOption_G1UsePrevMarking:
3051 return hr->obj_allocated_since_prev_marking(obj);
3052 case VerifyOption_G1UseNextMarking:
3053 return hr->obj_allocated_since_next_marking(obj);
3054 case VerifyOption_G1UseMarkWord:
3055 return false;
3056 default:
3057 ShouldNotReachHere();
3058 }
3059 return false; // keep some compilers happy
3060 }
3061
3062 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3063 switch (vo) {
3064 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3065 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3066 case VerifyOption_G1UseMarkWord: return NULL;
3067 default: ShouldNotReachHere();
3068 }
3069 return NULL; // keep some compilers happy
3070 }
3071
3072 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3073 switch (vo) {
3074 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3075 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3076 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3077 default: ShouldNotReachHere();
3078 }
3079 return false; // keep some compilers happy
3080 }
3081
3082 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3083 switch (vo) {
3084 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3085 case VerifyOption_G1UseNextMarking: return "NTAMS";
3086 case VerifyOption_G1UseMarkWord: return "NONE";
3087 default: ShouldNotReachHere();
3088 }
3089 return NULL; // keep some compilers happy
3090 }
3091
3092 class VerifyRootsClosure: public OopClosure {
3093 private:
3094 G1CollectedHeap* _g1h;
3095 VerifyOption _vo;
3096 bool _failures;
3097 public:
3098 // _vo == UsePrevMarking -> use "prev" marking information,
3099 // _vo == UseNextMarking -> use "next" marking information,
3100 // _vo == UseMarkWord -> use mark word from object header.
3101 VerifyRootsClosure(VerifyOption vo) :
3102 _g1h(G1CollectedHeap::heap()),
3103 _vo(vo),
3104 _failures(false) { }
3105
3106 bool failures() { return _failures; }
3107
3108 template <class T> void do_oop_nv(T* p) {
3109 T heap_oop = oopDesc::load_heap_oop(p);
3110 if (!oopDesc::is_null(heap_oop)) {
3111 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3112 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3113 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3114 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3115 if (_vo == VerifyOption_G1UseMarkWord) {
3116 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3117 }
3118 obj->print_on(gclog_or_tty);
3119 _failures = true;
3120 }
3121 }
3122 }
3123
3124 void do_oop(oop* p) { do_oop_nv(p); }
3125 void do_oop(narrowOop* p) { do_oop_nv(p); }
3126 };
3127
3128 class G1VerifyCodeRootOopClosure: public OopClosure {
3129 G1CollectedHeap* _g1h;
3130 OopClosure* _root_cl;
3131 nmethod* _nm;
3132 VerifyOption _vo;
3133 bool _failures;
3134
3135 template <class T> void do_oop_work(T* p) {
3136 // First verify that this root is live
3137 _root_cl->do_oop(p);
3138
3139 if (!G1VerifyHeapRegionCodeRoots) {
3140 // We're not verifying the code roots attached to heap region.
3141 return;
3142 }
3143
3144 // Don't check the code roots during marking verification in a full GC
3145 if (_vo == VerifyOption_G1UseMarkWord) {
3146 return;
3147 }
3148
3149 // Now verify that the current nmethod (which contains p) is
3150 // in the code root list of the heap region containing the
3151 // object referenced by p.
3152
3153 T heap_oop = oopDesc::load_heap_oop(p);
3154 if (!oopDesc::is_null(heap_oop)) {
3155 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3156
3157 // Now fetch the region containing the object
3158 HeapRegion* hr = _g1h->heap_region_containing(obj);
3159 HeapRegionRemSet* hrrs = hr->rem_set();
3160 // Verify that the strong code root list for this region
3161 // contains the nmethod
3162 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3163 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3164 "from nmethod "PTR_FORMAT" not in strong "
3165 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3166 p, _nm, hr->bottom(), hr->end());
3167 _failures = true;
3168 }
3169 }
3170 }
3171
3172 public:
3173 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3174 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3175
3176 void do_oop(oop* p) { do_oop_work(p); }
3177 void do_oop(narrowOop* p) { do_oop_work(p); }
3178
3179 void set_nmethod(nmethod* nm) { _nm = nm; }
3180 bool failures() { return _failures; }
3181 };
3182
3183 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3184 G1VerifyCodeRootOopClosure* _oop_cl;
3185
3186 public:
3187 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3188 _oop_cl(oop_cl) {}
3189
3190 void do_code_blob(CodeBlob* cb) {
3191 nmethod* nm = cb->as_nmethod_or_null();
3192 if (nm != NULL) {
3193 _oop_cl->set_nmethod(nm);
3194 nm->oops_do(_oop_cl);
3195 }
3196 }
3197 };
3198
3199 class YoungRefCounterClosure : public OopClosure {
3200 G1CollectedHeap* _g1h;
3201 int _count;
3202 public:
3203 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3204 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3205 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3206
3207 int count() { return _count; }
3208 void reset_count() { _count = 0; };
3209 };
3210
3211 class VerifyKlassClosure: public KlassClosure {
3212 YoungRefCounterClosure _young_ref_counter_closure;
3213 OopClosure *_oop_closure;
3214 public:
3215 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3216 void do_klass(Klass* k) {
3217 k->oops_do(_oop_closure);
3218
3219 _young_ref_counter_closure.reset_count();
3220 k->oops_do(&_young_ref_counter_closure);
3221 if (_young_ref_counter_closure.count() > 0) {
3222 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3223 }
3224 }
3225 };
3226
3227 class VerifyLivenessOopClosure: public OopClosure {
3228 G1CollectedHeap* _g1h;
3229 VerifyOption _vo;
3230 public:
3231 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3232 _g1h(g1h), _vo(vo)
3233 { }
3234 void do_oop(narrowOop *p) { do_oop_work(p); }
3235 void do_oop( oop *p) { do_oop_work(p); }
3236
3237 template <class T> void do_oop_work(T *p) {
3238 oop obj = oopDesc::load_decode_heap_oop(p);
3239 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3240 "Dead object referenced by a not dead object");
3241 }
3242 };
3243
3244 class VerifyObjsInRegionClosure: public ObjectClosure {
3245 private:
3246 G1CollectedHeap* _g1h;
3247 size_t _live_bytes;
3248 HeapRegion *_hr;
3249 VerifyOption _vo;
3250 public:
3251 // _vo == UsePrevMarking -> use "prev" marking information,
3252 // _vo == UseNextMarking -> use "next" marking information,
3253 // _vo == UseMarkWord -> use mark word from object header.
3254 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3255 : _live_bytes(0), _hr(hr), _vo(vo) {
3256 _g1h = G1CollectedHeap::heap();
3257 }
3258 void do_object(oop o) {
3259 VerifyLivenessOopClosure isLive(_g1h, _vo);
3260 assert(o != NULL, "Huh?");
3261 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3262 // If the object is alive according to the mark word,
3263 // then verify that the marking information agrees.
3264 // Note we can't verify the contra-positive of the
3265 // above: if the object is dead (according to the mark
3266 // word), it may not be marked, or may have been marked
3267 // but has since became dead, or may have been allocated
3268 // since the last marking.
3269 if (_vo == VerifyOption_G1UseMarkWord) {
3270 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3271 }
3272
3273 o->oop_iterate_no_header(&isLive);
3274 if (!_hr->obj_allocated_since_prev_marking(o)) {
3275 size_t obj_size = o->size(); // Make sure we don't overflow
3276 _live_bytes += (obj_size * HeapWordSize);
3277 }
3278 }
3279 }
3280 size_t live_bytes() { return _live_bytes; }
3281 };
3282
3283 class PrintObjsInRegionClosure : public ObjectClosure {
3284 HeapRegion *_hr;
3285 G1CollectedHeap *_g1;
3286 public:
3287 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3288 _g1 = G1CollectedHeap::heap();
3289 };
3290
3291 void do_object(oop o) {
3292 if (o != NULL) {
3293 HeapWord *start = (HeapWord *) o;
3294 size_t word_sz = o->size();
3295 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3296 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3297 (void*) o, word_sz,
3298 _g1->isMarkedPrev(o),
3299 _g1->isMarkedNext(o),
3300 _hr->obj_allocated_since_prev_marking(o));
3301 HeapWord *end = start + word_sz;
3302 HeapWord *cur;
3303 int *val;
3304 for (cur = start; cur < end; cur++) {
3305 val = (int *) cur;
3306 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3307 }
3308 }
3309 }
3310 };
3311
3312 class VerifyRegionClosure: public HeapRegionClosure {
3313 private:
3314 bool _par;
3315 VerifyOption _vo;
3316 bool _failures;
3317 public:
3318 // _vo == UsePrevMarking -> use "prev" marking information,
3319 // _vo == UseNextMarking -> use "next" marking information,
3320 // _vo == UseMarkWord -> use mark word from object header.
3321 VerifyRegionClosure(bool par, VerifyOption vo)
3322 : _par(par),
3323 _vo(vo),
3324 _failures(false) {}
3325
3326 bool failures() {
3327 return _failures;
3328 }
3329
3330 bool doHeapRegion(HeapRegion* r) {
3331 if (!r->continuesHumongous()) {
3332 bool failures = false;
3333 r->verify(_vo, &failures);
3334 if (failures) {
3335 _failures = true;
3336 } else {
3337 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3338 r->object_iterate(¬_dead_yet_cl);
3339 if (_vo != VerifyOption_G1UseNextMarking) {
3340 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3341 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3342 "max_live_bytes "SIZE_FORMAT" "
3343 "< calculated "SIZE_FORMAT,
3344 r->bottom(), r->end(),
3345 r->max_live_bytes(),
3346 not_dead_yet_cl.live_bytes());
3347 _failures = true;
3348 }
3349 } else {
3350 // When vo == UseNextMarking we cannot currently do a sanity
3351 // check on the live bytes as the calculation has not been
3352 // finalized yet.
3353 }
3354 }
3355 }
3356 return false; // stop the region iteration if we hit a failure
3357 }
3358 };
3359
3360 // This is the task used for parallel verification of the heap regions
3361
3362 class G1ParVerifyTask: public AbstractGangTask {
3363 private:
3364 G1CollectedHeap* _g1h;
3365 VerifyOption _vo;
3366 bool _failures;
3367
3368 public:
3369 // _vo == UsePrevMarking -> use "prev" marking information,
3370 // _vo == UseNextMarking -> use "next" marking information,
3371 // _vo == UseMarkWord -> use mark word from object header.
3372 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3373 AbstractGangTask("Parallel verify task"),
3374 _g1h(g1h),
3375 _vo(vo),
3376 _failures(false) { }
3377
3378 bool failures() {
3379 return _failures;
3380 }
3381
3382 void work(uint worker_id) {
3383 HandleMark hm;
3384 VerifyRegionClosure blk(true, _vo);
3385 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3386 _g1h->workers()->active_workers(),
3387 HeapRegion::ParVerifyClaimValue);
3388 if (blk.failures()) {
3389 _failures = true;
3390 }
3391 }
3392 };
3393
3394 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3395 if (SafepointSynchronize::is_at_safepoint()) {
3396 assert(Thread::current()->is_VM_thread(),
3397 "Expected to be executed serially by the VM thread at this point");
3398
3399 if (!silent) { gclog_or_tty->print("Roots "); }
3400 VerifyRootsClosure rootsCl(vo);
3401 VerifyKlassClosure klassCl(this, &rootsCl);
3402
3403 // We apply the relevant closures to all the oops in the
3404 // system dictionary, class loader data graph and the string table.
3405 // Don't verify the code cache here, since it's verified below.
3406 const int so = SO_AllClasses | SO_Strings;
3407
3408 // Need cleared claim bits for the strong roots processing
3409 ClassLoaderDataGraph::clear_claimed_marks();
3410
3411 process_strong_roots(true, // activate StrongRootsScope
3412 ScanningOption(so), // roots scanning options
3413 &rootsCl,
3414 &klassCl
3415 );
3416
3417 // Verify the nmethods in the code cache.
3418 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3419 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3420 CodeCache::blobs_do(&blobsCl);
3421
3422 bool failures = rootsCl.failures() || codeRootsCl.failures();
3423
3424 if (vo != VerifyOption_G1UseMarkWord) {
3425 // If we're verifying during a full GC then the region sets
3426 // will have been torn down at the start of the GC. Therefore
3427 // verifying the region sets will fail. So we only verify
3428 // the region sets when not in a full GC.
3429 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3430 verify_region_sets();
3431 }
3432
3433 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3434 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3435 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3436 "sanity check");
3437
3438 G1ParVerifyTask task(this, vo);
3439 assert(UseDynamicNumberOfGCThreads ||
3440 workers()->active_workers() == workers()->total_workers(),
3441 "If not dynamic should be using all the workers");
3442 int n_workers = workers()->active_workers();
3443 set_par_threads(n_workers);
3444 workers()->run_task(&task);
3445 set_par_threads(0);
3446 if (task.failures()) {
3447 failures = true;
3448 }
3449
3450 // Checks that the expected amount of parallel work was done.
3451 // The implication is that n_workers is > 0.
3452 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3453 "sanity check");
3454
3455 reset_heap_region_claim_values();
3456
3457 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3458 "sanity check");
3459 } else {
3460 VerifyRegionClosure blk(false, vo);
3461 heap_region_iterate(&blk);
3462 if (blk.failures()) {
3463 failures = true;
3464 }
3465 }
3466 if (!silent) gclog_or_tty->print("RemSet ");
3467 rem_set()->verify();
3468
3469 if (G1StringDedup::is_enabled()) {
3470 if (!silent) gclog_or_tty->print("StrDedup ");
3471 G1StringDedup::verify();
3472 }
3473
3474 if (failures) {
3475 gclog_or_tty->print_cr("Heap:");
3476 // It helps to have the per-region information in the output to
3477 // help us track down what went wrong. This is why we call
3478 // print_extended_on() instead of print_on().
3479 print_extended_on(gclog_or_tty);
3480 gclog_or_tty->cr();
3481 #ifndef PRODUCT
3482 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3483 concurrent_mark()->print_reachable("at-verification-failure",
3484 vo, false /* all */);
3485 }
3486 #endif
3487 gclog_or_tty->flush();
3488 }
3489 guarantee(!failures, "there should not have been any failures");
3490 } else {
3491 if (!silent) {
3492 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3493 if (G1StringDedup::is_enabled()) {
3494 gclog_or_tty->print(", StrDedup");
3495 }
3496 gclog_or_tty->print(") ");
3497 }
3498 }
3499 }
3500
3501 void G1CollectedHeap::verify(bool silent) {
3502 verify(silent, VerifyOption_G1UsePrevMarking);
3503 }
3504
3505 double G1CollectedHeap::verify(bool guard, const char* msg) {
3506 double verify_time_ms = 0.0;
3507
3508 if (guard && total_collections() >= VerifyGCStartAt) {
3509 double verify_start = os::elapsedTime();
3510 HandleMark hm; // Discard invalid handles created during verification
3511 prepare_for_verify();
3512 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3513 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3514 }
3515
3516 return verify_time_ms;
3517 }
3518
3519 void G1CollectedHeap::verify_before_gc() {
3520 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3521 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3522 }
3523
3524 void G1CollectedHeap::verify_after_gc() {
3525 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3526 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3527 }
3528
3529 class PrintRegionClosure: public HeapRegionClosure {
3530 outputStream* _st;
3531 public:
3532 PrintRegionClosure(outputStream* st) : _st(st) {}
3533 bool doHeapRegion(HeapRegion* r) {
3534 r->print_on(_st);
3535 return false;
3536 }
3537 };
3538
3539 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3540 const HeapRegion* hr,
3541 const VerifyOption vo) const {
3542 switch (vo) {
3543 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3544 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3545 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3546 default: ShouldNotReachHere();
3547 }
3548 return false; // keep some compilers happy
3549 }
3550
3551 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3552 const VerifyOption vo) const {
3553 switch (vo) {
3554 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3555 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3556 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3557 default: ShouldNotReachHere();
3558 }
3559 return false; // keep some compilers happy
3560 }
3561
3562 void G1CollectedHeap::print_on(outputStream* st) const {
3563 st->print(" %-20s", "garbage-first heap");
3564 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3565 capacity()/K, used_unlocked()/K);
3566 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3567 _g1_storage.low_boundary(),
3568 _g1_storage.high(),
3569 _g1_storage.high_boundary());
3570 st->cr();
3571 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3572 uint young_regions = _young_list->length();
3573 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3574 (size_t) young_regions * HeapRegion::GrainBytes / K);
3575 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3576 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3577 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3578 st->cr();
3579 MetaspaceAux::print_on(st);
3580 }
3581
3582 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3583 print_on(st);
3584
3585 // Print the per-region information.
3586 st->cr();
3587 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3588 "HS=humongous(starts), HC=humongous(continues), "
3589 "CS=collection set, F=free, TS=gc time stamp, "
3590 "PTAMS=previous top-at-mark-start, "
3591 "NTAMS=next top-at-mark-start)");
3592 PrintRegionClosure blk(st);
3593 heap_region_iterate(&blk);
3594 }
3595
3596 void G1CollectedHeap::print_on_error(outputStream* st) const {
3597 this->CollectedHeap::print_on_error(st);
3598
3599 if (_cm != NULL) {
3600 st->cr();
3601 _cm->print_on_error(st);
3602 }
3603 }
3604
3605 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3606 if (G1CollectedHeap::use_parallel_gc_threads()) {
3607 workers()->print_worker_threads_on(st);
3608 }
3609 _cmThread->print_on(st);
3610 st->cr();
3611 _cm->print_worker_threads_on(st);
3612 _cg1r->print_worker_threads_on(st);
3613 if (G1StringDedup::is_enabled()) {
3614 G1StringDedup::print_worker_threads_on(st);
3615 }
3616 }
3617
3618 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3619 if (G1CollectedHeap::use_parallel_gc_threads()) {
3620 workers()->threads_do(tc);
3621 }
3622 tc->do_thread(_cmThread);
3623 _cg1r->threads_do(tc);
3624 if (G1StringDedup::is_enabled()) {
3625 G1StringDedup::threads_do(tc);
3626 }
3627 }
3628
3629 void G1CollectedHeap::print_tracing_info() const {
3630 // We'll overload this to mean "trace GC pause statistics."
3631 if (TraceGen0Time || TraceGen1Time) {
3632 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3633 // to that.
3634 g1_policy()->print_tracing_info();
3635 }
3636 if (G1SummarizeRSetStats) {
3637 g1_rem_set()->print_summary_info();
3638 }
3639 if (G1SummarizeConcMark) {
3640 concurrent_mark()->print_summary_info();
3641 }
3642 g1_policy()->print_yg_surv_rate_info();
3643 SpecializationStats::print();
3644 }
3645
3646 #ifndef PRODUCT
3647 // Helpful for debugging RSet issues.
3648
3649 class PrintRSetsClosure : public HeapRegionClosure {
3650 private:
3651 const char* _msg;
3652 size_t _occupied_sum;
3653
3654 public:
3655 bool doHeapRegion(HeapRegion* r) {
3656 HeapRegionRemSet* hrrs = r->rem_set();
3657 size_t occupied = hrrs->occupied();
3658 _occupied_sum += occupied;
3659
3660 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3661 HR_FORMAT_PARAMS(r));
3662 if (occupied == 0) {
3663 gclog_or_tty->print_cr(" RSet is empty");
3664 } else {
3665 hrrs->print();
3666 }
3667 gclog_or_tty->print_cr("----------");
3668 return false;
3669 }
3670
3671 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3672 gclog_or_tty->cr();
3673 gclog_or_tty->print_cr("========================================");
3674 gclog_or_tty->print_cr("%s", msg);
3675 gclog_or_tty->cr();
3676 }
3677
3678 ~PrintRSetsClosure() {
3679 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3680 gclog_or_tty->print_cr("========================================");
3681 gclog_or_tty->cr();
3682 }
3683 };
3684
3685 void G1CollectedHeap::print_cset_rsets() {
3686 PrintRSetsClosure cl("Printing CSet RSets");
3687 collection_set_iterate(&cl);
3688 }
3689
3690 void G1CollectedHeap::print_all_rsets() {
3691 PrintRSetsClosure cl("Printing All RSets");;
3692 heap_region_iterate(&cl);
3693 }
3694 #endif // PRODUCT
3695
3696 G1CollectedHeap* G1CollectedHeap::heap() {
3697 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3698 "not a garbage-first heap");
3699 return _g1h;
3700 }
3701
3702 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3703 // always_do_update_barrier = false;
3704 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3705 // Fill TLAB's and such
3706 accumulate_statistics_all_tlabs();
3707 ensure_parsability(true);
3708
3709 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3710 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3711 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3712 }
3713 }
3714
3715 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3716
3717 if (G1SummarizeRSetStats &&
3718 (G1SummarizeRSetStatsPeriod > 0) &&
3719 // we are at the end of the GC. Total collections has already been increased.
3720 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3721 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3722 }
3723
3724 // FIXME: what is this about?
3725 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3726 // is set.
3727 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3728 "derived pointer present"));
3729 // always_do_update_barrier = true;
3730
3731 resize_all_tlabs();
3732
3733 // We have just completed a GC. Update the soft reference
3734 // policy with the new heap occupancy
3735 Universe::update_heap_info_at_gc();
3736 }
3737
3738 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3739 unsigned int gc_count_before,
3740 bool* succeeded,
3741 GCCause::Cause gc_cause) {
3742 assert_heap_not_locked_and_not_at_safepoint();
3743 g1_policy()->record_stop_world_start();
3744 VM_G1IncCollectionPause op(gc_count_before,
3745 word_size,
3746 false, /* should_initiate_conc_mark */
3747 g1_policy()->max_pause_time_ms(),
3748 gc_cause);
3749 VMThread::execute(&op);
3750
3751 HeapWord* result = op.result();
3752 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3753 assert(result == NULL || ret_succeeded,
3754 "the result should be NULL if the VM did not succeed");
3755 *succeeded = ret_succeeded;
3756
3757 assert_heap_not_locked();
3758 return result;
3759 }
3760
3761 void
3762 G1CollectedHeap::doConcurrentMark() {
3763 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3764 if (!_cmThread->in_progress()) {
3765 _cmThread->set_started();
3766 CGC_lock->notify();
3767 }
3768 }
3769
3770 size_t G1CollectedHeap::pending_card_num() {
3771 size_t extra_cards = 0;
3772 JavaThread *curr = Threads::first();
3773 while (curr != NULL) {
3774 DirtyCardQueue& dcq = curr->dirty_card_queue();
3775 extra_cards += dcq.size();
3776 curr = curr->next();
3777 }
3778 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3779 size_t buffer_size = dcqs.buffer_size();
3780 size_t buffer_num = dcqs.completed_buffers_num();
3781
3782 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3783 // in bytes - not the number of 'entries'. We need to convert
3784 // into a number of cards.
3785 return (buffer_size * buffer_num + extra_cards) / oopSize;
3786 }
3787
3788 size_t G1CollectedHeap::cards_scanned() {
3789 return g1_rem_set()->cardsScanned();
3790 }
3791
3792 void
3793 G1CollectedHeap::setup_surviving_young_words() {
3794 assert(_surviving_young_words == NULL, "pre-condition");
3795 uint array_length = g1_policy()->young_cset_region_length();
3796 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3797 if (_surviving_young_words == NULL) {
3798 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3799 "Not enough space for young surv words summary.");
3800 }
3801 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3802 #ifdef ASSERT
3803 for (uint i = 0; i < array_length; ++i) {
3804 assert( _surviving_young_words[i] == 0, "memset above" );
3805 }
3806 #endif // !ASSERT
3807 }
3808
3809 void
3810 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3811 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3812 uint array_length = g1_policy()->young_cset_region_length();
3813 for (uint i = 0; i < array_length; ++i) {
3814 _surviving_young_words[i] += surv_young_words[i];
3815 }
3816 }
3817
3818 void
3819 G1CollectedHeap::cleanup_surviving_young_words() {
3820 guarantee( _surviving_young_words != NULL, "pre-condition" );
3821 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3822 _surviving_young_words = NULL;
3823 }
3824
3825 #ifdef ASSERT
3826 class VerifyCSetClosure: public HeapRegionClosure {
3827 public:
3828 bool doHeapRegion(HeapRegion* hr) {
3829 // Here we check that the CSet region's RSet is ready for parallel
3830 // iteration. The fields that we'll verify are only manipulated
3831 // when the region is part of a CSet and is collected. Afterwards,
3832 // we reset these fields when we clear the region's RSet (when the
3833 // region is freed) so they are ready when the region is
3834 // re-allocated. The only exception to this is if there's an
3835 // evacuation failure and instead of freeing the region we leave
3836 // it in the heap. In that case, we reset these fields during
3837 // evacuation failure handling.
3838 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3839
3840 // Here's a good place to add any other checks we'd like to
3841 // perform on CSet regions.
3842 return false;
3843 }
3844 };
3845 #endif // ASSERT
3846
3847 #if TASKQUEUE_STATS
3848 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3849 st->print_raw_cr("GC Task Stats");
3850 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3851 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3852 }
3853
3854 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3855 print_taskqueue_stats_hdr(st);
3856
3857 TaskQueueStats totals;
3858 const int n = workers() != NULL ? workers()->total_workers() : 1;
3859 for (int i = 0; i < n; ++i) {
3860 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3861 totals += task_queue(i)->stats;
3862 }
3863 st->print_raw("tot "); totals.print(st); st->cr();
3864
3865 DEBUG_ONLY(totals.verify());
3866 }
3867
3868 void G1CollectedHeap::reset_taskqueue_stats() {
3869 const int n = workers() != NULL ? workers()->total_workers() : 1;
3870 for (int i = 0; i < n; ++i) {
3871 task_queue(i)->stats.reset();
3872 }
3873 }
3874 #endif // TASKQUEUE_STATS
3875
3876 void G1CollectedHeap::log_gc_header() {
3877 if (!G1Log::fine()) {
3878 return;
3879 }
3880
3881 gclog_or_tty->date_stamp(PrintGCDateStamps);
3882 gclog_or_tty->stamp(PrintGCTimeStamps);
3883
3884 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3885 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3886 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3887
3888 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3889 }
3890
3891 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3892 if (!G1Log::fine()) {
3893 return;
3894 }
3895
3896 if (G1Log::finer()) {
3897 if (evacuation_failed()) {
3898 gclog_or_tty->print(" (to-space exhausted)");
3899 }
3900 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3901 g1_policy()->phase_times()->note_gc_end();
3902 g1_policy()->phase_times()->print(pause_time_sec);
3903 g1_policy()->print_detailed_heap_transition();
3904 } else {
3905 if (evacuation_failed()) {
3906 gclog_or_tty->print("--");
3907 }
3908 g1_policy()->print_heap_transition();
3909 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3910 }
3911 gclog_or_tty->flush();
3912 }
3913
3914 bool
3915 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3916 assert_at_safepoint(true /* should_be_vm_thread */);
3917 guarantee(!is_gc_active(), "collection is not reentrant");
3918
3919 if (GC_locker::check_active_before_gc()) {
3920 return false;
3921 }
3922
3923 _gc_timer_stw->register_gc_start();
3924
3925 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3926
3927 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3928 ResourceMark rm;
3929
3930 print_heap_before_gc();
3931 trace_heap_before_gc(_gc_tracer_stw);
3932
3933 verify_region_sets_optional();
3934 verify_dirty_young_regions();
3935
3936 // This call will decide whether this pause is an initial-mark
3937 // pause. If it is, during_initial_mark_pause() will return true
3938 // for the duration of this pause.
3939 g1_policy()->decide_on_conc_mark_initiation();
3940
3941 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3942 assert(!g1_policy()->during_initial_mark_pause() ||
3943 g1_policy()->gcs_are_young(), "sanity");
3944
3945 // We also do not allow mixed GCs during marking.
3946 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3947
3948 // Record whether this pause is an initial mark. When the current
3949 // thread has completed its logging output and it's safe to signal
3950 // the CM thread, the flag's value in the policy has been reset.
3951 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3952
3953 // Inner scope for scope based logging, timers, and stats collection
3954 {
3955 EvacuationInfo evacuation_info;
3956
3957 if (g1_policy()->during_initial_mark_pause()) {
3958 // We are about to start a marking cycle, so we increment the
3959 // full collection counter.
3960 increment_old_marking_cycles_started();
3961 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3962 }
3963
3964 _gc_tracer_stw->report_yc_type(yc_type());
3965
3966 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3967
3968 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3969 workers()->active_workers() : 1);
3970 double pause_start_sec = os::elapsedTime();
3971 g1_policy()->phase_times()->note_gc_start(active_workers);
3972 log_gc_header();
3973
3974 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3975 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3976
3977 // If the secondary_free_list is not empty, append it to the
3978 // free_list. No need to wait for the cleanup operation to finish;
3979 // the region allocation code will check the secondary_free_list
3980 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3981 // set, skip this step so that the region allocation code has to
3982 // get entries from the secondary_free_list.
3983 if (!G1StressConcRegionFreeing) {
3984 append_secondary_free_list_if_not_empty_with_lock();
3985 }
3986
3987 assert(check_young_list_well_formed(), "young list should be well formed");
3988 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3989 "sanity check");
3990
3991 // Don't dynamically change the number of GC threads this early. A value of
3992 // 0 is used to indicate serial work. When parallel work is done,
3993 // it will be set.
3994
3995 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3996 IsGCActiveMark x;
3997
3998 gc_prologue(false);
3999 increment_total_collections(false /* full gc */);
4000 increment_gc_time_stamp();
4001
4002 verify_before_gc();
4003 check_bitmaps("GC Start");
4004
4005 COMPILER2_PRESENT(DerivedPointerTable::clear());
4006
4007 // Please see comment in g1CollectedHeap.hpp and
4008 // G1CollectedHeap::ref_processing_init() to see how
4009 // reference processing currently works in G1.
4010
4011 // Enable discovery in the STW reference processor
4012 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4013 true /*verify_no_refs*/);
4014
4015 {
4016 // We want to temporarily turn off discovery by the
4017 // CM ref processor, if necessary, and turn it back on
4018 // on again later if we do. Using a scoped
4019 // NoRefDiscovery object will do this.
4020 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4021
4022 // Forget the current alloc region (we might even choose it to be part
4023 // of the collection set!).
4024 release_mutator_alloc_region();
4025
4026 // We should call this after we retire the mutator alloc
4027 // region(s) so that all the ALLOC / RETIRE events are generated
4028 // before the start GC event.
4029 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4030
4031 // This timing is only used by the ergonomics to handle our pause target.
4032 // It is unclear why this should not include the full pause. We will
4033 // investigate this in CR 7178365.
4034 //
4035 // Preserving the old comment here if that helps the investigation:
4036 //
4037 // The elapsed time induced by the start time below deliberately elides
4038 // the possible verification above.
4039 double sample_start_time_sec = os::elapsedTime();
4040
4041 #if YOUNG_LIST_VERBOSE
4042 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4043 _young_list->print();
4044 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4045 #endif // YOUNG_LIST_VERBOSE
4046
4047 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4048
4049 double scan_wait_start = os::elapsedTime();
4050 // We have to wait until the CM threads finish scanning the
4051 // root regions as it's the only way to ensure that all the
4052 // objects on them have been correctly scanned before we start
4053 // moving them during the GC.
4054 bool waited = _cm->root_regions()->wait_until_scan_finished();
4055 double wait_time_ms = 0.0;
4056 if (waited) {
4057 double scan_wait_end = os::elapsedTime();
4058 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4059 }
4060 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4061
4062 #if YOUNG_LIST_VERBOSE
4063 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4064 _young_list->print();
4065 #endif // YOUNG_LIST_VERBOSE
4066
4067 if (g1_policy()->during_initial_mark_pause()) {
4068 concurrent_mark()->checkpointRootsInitialPre();
4069 }
4070
4071 #if YOUNG_LIST_VERBOSE
4072 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4073 _young_list->print();
4074 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4075 #endif // YOUNG_LIST_VERBOSE
4076
4077 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4078
4079 _cm->note_start_of_gc();
4080 // We should not verify the per-thread SATB buffers given that
4081 // we have not filtered them yet (we'll do so during the
4082 // GC). We also call this after finalize_cset() to
4083 // ensure that the CSet has been finalized.
4084 _cm->verify_no_cset_oops(true /* verify_stacks */,
4085 true /* verify_enqueued_buffers */,
4086 false /* verify_thread_buffers */,
4087 true /* verify_fingers */);
4088
4089 if (_hr_printer.is_active()) {
4090 HeapRegion* hr = g1_policy()->collection_set();
4091 while (hr != NULL) {
4092 G1HRPrinter::RegionType type;
4093 if (!hr->is_young()) {
4094 type = G1HRPrinter::Old;
4095 } else if (hr->is_survivor()) {
4096 type = G1HRPrinter::Survivor;
4097 } else {
4098 type = G1HRPrinter::Eden;
4099 }
4100 _hr_printer.cset(hr);
4101 hr = hr->next_in_collection_set();
4102 }
4103 }
4104
4105 #ifdef ASSERT
4106 VerifyCSetClosure cl;
4107 collection_set_iterate(&cl);
4108 #endif // ASSERT
4109
4110 setup_surviving_young_words();
4111
4112 // Initialize the GC alloc regions.
4113 init_gc_alloc_regions(evacuation_info);
4114
4115 // Actually do the work...
4116 evacuate_collection_set(evacuation_info);
4117
4118 // We do this to mainly verify the per-thread SATB buffers
4119 // (which have been filtered by now) since we didn't verify
4120 // them earlier. No point in re-checking the stacks / enqueued
4121 // buffers given that the CSet has not changed since last time
4122 // we checked.
4123 _cm->verify_no_cset_oops(false /* verify_stacks */,
4124 false /* verify_enqueued_buffers */,
4125 true /* verify_thread_buffers */,
4126 true /* verify_fingers */);
4127
4128 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4129 g1_policy()->clear_collection_set();
4130
4131 cleanup_surviving_young_words();
4132
4133 // Start a new incremental collection set for the next pause.
4134 g1_policy()->start_incremental_cset_building();
4135
4136 clear_cset_fast_test();
4137
4138 _young_list->reset_sampled_info();
4139
4140 // Don't check the whole heap at this point as the
4141 // GC alloc regions from this pause have been tagged
4142 // as survivors and moved on to the survivor list.
4143 // Survivor regions will fail the !is_young() check.
4144 assert(check_young_list_empty(false /* check_heap */),
4145 "young list should be empty");
4146
4147 #if YOUNG_LIST_VERBOSE
4148 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4149 _young_list->print();
4150 #endif // YOUNG_LIST_VERBOSE
4151
4152 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4153 _young_list->first_survivor_region(),
4154 _young_list->last_survivor_region());
4155
4156 _young_list->reset_auxilary_lists();
4157
4158 if (evacuation_failed()) {
4159 _summary_bytes_used = recalculate_used();
4160 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4161 for (uint i = 0; i < n_queues; i++) {
4162 if (_evacuation_failed_info_array[i].has_failed()) {
4163 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4164 }
4165 }
4166 } else {
4167 // The "used" of the the collection set have already been subtracted
4168 // when they were freed. Add in the bytes evacuated.
4169 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4170 }
4171
4172 if (g1_policy()->during_initial_mark_pause()) {
4173 // We have to do this before we notify the CM threads that
4174 // they can start working to make sure that all the
4175 // appropriate initialization is done on the CM object.
4176 concurrent_mark()->checkpointRootsInitialPost();
4177 set_marking_started();
4178 // Note that we don't actually trigger the CM thread at
4179 // this point. We do that later when we're sure that
4180 // the current thread has completed its logging output.
4181 }
4182
4183 allocate_dummy_regions();
4184
4185 #if YOUNG_LIST_VERBOSE
4186 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4187 _young_list->print();
4188 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4189 #endif // YOUNG_LIST_VERBOSE
4190
4191 init_mutator_alloc_region();
4192
4193 {
4194 size_t expand_bytes = g1_policy()->expansion_amount();
4195 if (expand_bytes > 0) {
4196 size_t bytes_before = capacity();
4197 // No need for an ergo verbose message here,
4198 // expansion_amount() does this when it returns a value > 0.
4199 if (!expand(expand_bytes)) {
4200 // We failed to expand the heap so let's verify that
4201 // committed/uncommitted amount match the backing store
4202 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4203 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4204 }
4205 }
4206 }
4207
4208 // We redo the verification but now wrt to the new CSet which
4209 // has just got initialized after the previous CSet was freed.
4210 _cm->verify_no_cset_oops(true /* verify_stacks */,
4211 true /* verify_enqueued_buffers */,
4212 true /* verify_thread_buffers */,
4213 true /* verify_fingers */);
4214 _cm->note_end_of_gc();
4215
4216 // This timing is only used by the ergonomics to handle our pause target.
4217 // It is unclear why this should not include the full pause. We will
4218 // investigate this in CR 7178365.
4219 double sample_end_time_sec = os::elapsedTime();
4220 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4221 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4222
4223 MemoryService::track_memory_usage();
4224
4225 // In prepare_for_verify() below we'll need to scan the deferred
4226 // update buffers to bring the RSets up-to-date if
4227 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4228 // the update buffers we'll probably need to scan cards on the
4229 // regions we just allocated to (i.e., the GC alloc
4230 // regions). However, during the last GC we called
4231 // set_saved_mark() on all the GC alloc regions, so card
4232 // scanning might skip the [saved_mark_word()...top()] area of
4233 // those regions (i.e., the area we allocated objects into
4234 // during the last GC). But it shouldn't. Given that
4235 // saved_mark_word() is conditional on whether the GC time stamp
4236 // on the region is current or not, by incrementing the GC time
4237 // stamp here we invalidate all the GC time stamps on all the
4238 // regions and saved_mark_word() will simply return top() for
4239 // all the regions. This is a nicer way of ensuring this rather
4240 // than iterating over the regions and fixing them. In fact, the
4241 // GC time stamp increment here also ensures that
4242 // saved_mark_word() will return top() between pauses, i.e.,
4243 // during concurrent refinement. So we don't need the
4244 // is_gc_active() check to decided which top to use when
4245 // scanning cards (see CR 7039627).
4246 increment_gc_time_stamp();
4247
4248 verify_after_gc();
4249 check_bitmaps("GC End");
4250
4251 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4252 ref_processor_stw()->verify_no_references_recorded();
4253
4254 // CM reference discovery will be re-enabled if necessary.
4255 }
4256
4257 // We should do this after we potentially expand the heap so
4258 // that all the COMMIT events are generated before the end GC
4259 // event, and after we retire the GC alloc regions so that all
4260 // RETIRE events are generated before the end GC event.
4261 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4262
4263 if (mark_in_progress()) {
4264 concurrent_mark()->update_g1_committed();
4265 }
4266
4267 #ifdef TRACESPINNING
4268 ParallelTaskTerminator::print_termination_counts();
4269 #endif
4270
4271 gc_epilogue(false);
4272 }
4273
4274 // Print the remainder of the GC log output.
4275 log_gc_footer(os::elapsedTime() - pause_start_sec);
4276
4277 // It is not yet to safe to tell the concurrent mark to
4278 // start as we have some optional output below. We don't want the
4279 // output from the concurrent mark thread interfering with this
4280 // logging output either.
4281
4282 _hrs.verify_optional();
4283 verify_region_sets_optional();
4284
4285 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4286 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4287
4288 print_heap_after_gc();
4289 trace_heap_after_gc(_gc_tracer_stw);
4290
4291 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4292 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4293 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4294 // before any GC notifications are raised.
4295 g1mm()->update_sizes();
4296
4297 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4298 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4299 _gc_timer_stw->register_gc_end();
4300 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4301 }
4302 // It should now be safe to tell the concurrent mark thread to start
4303 // without its logging output interfering with the logging output
4304 // that came from the pause.
4305
4306 if (should_start_conc_mark) {
4307 // CAUTION: after the doConcurrentMark() call below,
4308 // the concurrent marking thread(s) could be running
4309 // concurrently with us. Make sure that anything after
4310 // this point does not assume that we are the only GC thread
4311 // running. Note: of course, the actual marking work will
4312 // not start until the safepoint itself is released in
4313 // SuspendibleThreadSet::desynchronize().
4314 doConcurrentMark();
4315 }
4316
4317 return true;
4318 }
4319
4320 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4321 {
4322 size_t gclab_word_size;
4323 switch (purpose) {
4324 case GCAllocForSurvived:
4325 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4326 break;
4327 case GCAllocForTenured:
4328 gclab_word_size = _old_plab_stats.desired_plab_sz();
4329 break;
4330 default:
4331 assert(false, "unknown GCAllocPurpose");
4332 gclab_word_size = _old_plab_stats.desired_plab_sz();
4333 break;
4334 }
4335
4336 // Prevent humongous PLAB sizes for two reasons:
4337 // * PLABs are allocated using a similar paths as oops, but should
4338 // never be in a humongous region
4339 // * Allowing humongous PLABs needlessly churns the region free lists
4340 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4341 }
4342
4343 void G1CollectedHeap::init_mutator_alloc_region() {
4344 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4345 _mutator_alloc_region.init();
4346 }
4347
4348 void G1CollectedHeap::release_mutator_alloc_region() {
4349 _mutator_alloc_region.release();
4350 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4351 }
4352
4353 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4354 assert_at_safepoint(true /* should_be_vm_thread */);
4355
4356 _survivor_gc_alloc_region.init();
4357 _old_gc_alloc_region.init();
4358 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4359 _retained_old_gc_alloc_region = NULL;
4360
4361 // We will discard the current GC alloc region if:
4362 // a) it's in the collection set (it can happen!),
4363 // b) it's already full (no point in using it),
4364 // c) it's empty (this means that it was emptied during
4365 // a cleanup and it should be on the free list now), or
4366 // d) it's humongous (this means that it was emptied
4367 // during a cleanup and was added to the free list, but
4368 // has been subsequently used to allocate a humongous
4369 // object that may be less than the region size).
4370 if (retained_region != NULL &&
4371 !retained_region->in_collection_set() &&
4372 !(retained_region->top() == retained_region->end()) &&
4373 !retained_region->is_empty() &&
4374 !retained_region->isHumongous()) {
4375 retained_region->set_saved_mark();
4376 // The retained region was added to the old region set when it was
4377 // retired. We have to remove it now, since we don't allow regions
4378 // we allocate to in the region sets. We'll re-add it later, when
4379 // it's retired again.
4380 _old_set.remove(retained_region);
4381 bool during_im = g1_policy()->during_initial_mark_pause();
4382 retained_region->note_start_of_copying(during_im);
4383 _old_gc_alloc_region.set(retained_region);
4384 _hr_printer.reuse(retained_region);
4385 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4386 }
4387 }
4388
4389 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4390 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4391 _old_gc_alloc_region.count());
4392 _survivor_gc_alloc_region.release();
4393 // If we have an old GC alloc region to release, we'll save it in
4394 // _retained_old_gc_alloc_region. If we don't
4395 // _retained_old_gc_alloc_region will become NULL. This is what we
4396 // want either way so no reason to check explicitly for either
4397 // condition.
4398 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4399
4400 if (ResizePLAB) {
4401 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4402 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4403 }
4404 }
4405
4406 void G1CollectedHeap::abandon_gc_alloc_regions() {
4407 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4408 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4409 _retained_old_gc_alloc_region = NULL;
4410 }
4411
4412 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4413 _drain_in_progress = false;
4414 set_evac_failure_closure(cl);
4415 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4416 }
4417
4418 void G1CollectedHeap::finalize_for_evac_failure() {
4419 assert(_evac_failure_scan_stack != NULL &&
4420 _evac_failure_scan_stack->length() == 0,
4421 "Postcondition");
4422 assert(!_drain_in_progress, "Postcondition");
4423 delete _evac_failure_scan_stack;
4424 _evac_failure_scan_stack = NULL;
4425 }
4426
4427 void G1CollectedHeap::remove_self_forwarding_pointers() {
4428 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4429
4430 double remove_self_forwards_start = os::elapsedTime();
4431
4432 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4433
4434 if (G1CollectedHeap::use_parallel_gc_threads()) {
4435 set_par_threads();
4436 workers()->run_task(&rsfp_task);
4437 set_par_threads(0);
4438 } else {
4439 rsfp_task.work(0);
4440 }
4441
4442 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4443
4444 // Reset the claim values in the regions in the collection set.
4445 reset_cset_heap_region_claim_values();
4446
4447 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4448
4449 // Now restore saved marks, if any.
4450 assert(_objs_with_preserved_marks.size() ==
4451 _preserved_marks_of_objs.size(), "Both or none.");
4452 while (!_objs_with_preserved_marks.is_empty()) {
4453 oop obj = _objs_with_preserved_marks.pop();
4454 markOop m = _preserved_marks_of_objs.pop();
4455 obj->set_mark(m);
4456 }
4457 _objs_with_preserved_marks.clear(true);
4458 _preserved_marks_of_objs.clear(true);
4459
4460 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4461 }
4462
4463 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4464 _evac_failure_scan_stack->push(obj);
4465 }
4466
4467 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4468 assert(_evac_failure_scan_stack != NULL, "precondition");
4469
4470 while (_evac_failure_scan_stack->length() > 0) {
4471 oop obj = _evac_failure_scan_stack->pop();
4472 _evac_failure_closure->set_region(heap_region_containing(obj));
4473 obj->oop_iterate_backwards(_evac_failure_closure);
4474 }
4475 }
4476
4477 oop
4478 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4479 oop old) {
4480 assert(obj_in_cs(old),
4481 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4482 (HeapWord*) old));
4483 markOop m = old->mark();
4484 oop forward_ptr = old->forward_to_atomic(old);
4485 if (forward_ptr == NULL) {
4486 // Forward-to-self succeeded.
4487 assert(_par_scan_state != NULL, "par scan state");
4488 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4489 uint queue_num = _par_scan_state->queue_num();
4490
4491 _evacuation_failed = true;
4492 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4493 if (_evac_failure_closure != cl) {
4494 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4495 assert(!_drain_in_progress,
4496 "Should only be true while someone holds the lock.");
4497 // Set the global evac-failure closure to the current thread's.
4498 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4499 set_evac_failure_closure(cl);
4500 // Now do the common part.
4501 handle_evacuation_failure_common(old, m);
4502 // Reset to NULL.
4503 set_evac_failure_closure(NULL);
4504 } else {
4505 // The lock is already held, and this is recursive.
4506 assert(_drain_in_progress, "This should only be the recursive case.");
4507 handle_evacuation_failure_common(old, m);
4508 }
4509 return old;
4510 } else {
4511 // Forward-to-self failed. Either someone else managed to allocate
4512 // space for this object (old != forward_ptr) or they beat us in
4513 // self-forwarding it (old == forward_ptr).
4514 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4515 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4516 "should not be in the CSet",
4517 (HeapWord*) old, (HeapWord*) forward_ptr));
4518 return forward_ptr;
4519 }
4520 }
4521
4522 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4523 preserve_mark_if_necessary(old, m);
4524
4525 HeapRegion* r = heap_region_containing(old);
4526 if (!r->evacuation_failed()) {
4527 r->set_evacuation_failed(true);
4528 _hr_printer.evac_failure(r);
4529 }
4530
4531 push_on_evac_failure_scan_stack(old);
4532
4533 if (!_drain_in_progress) {
4534 // prevent recursion in copy_to_survivor_space()
4535 _drain_in_progress = true;
4536 drain_evac_failure_scan_stack();
4537 _drain_in_progress = false;
4538 }
4539 }
4540
4541 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4542 assert(evacuation_failed(), "Oversaving!");
4543 // We want to call the "for_promotion_failure" version only in the
4544 // case of a promotion failure.
4545 if (m->must_be_preserved_for_promotion_failure(obj)) {
4546 _objs_with_preserved_marks.push(obj);
4547 _preserved_marks_of_objs.push(m);
4548 }
4549 }
4550
4551 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4552 size_t word_size) {
4553 if (purpose == GCAllocForSurvived) {
4554 HeapWord* result = survivor_attempt_allocation(word_size);
4555 if (result != NULL) {
4556 return result;
4557 } else {
4558 // Let's try to allocate in the old gen in case we can fit the
4559 // object there.
4560 return old_attempt_allocation(word_size);
4561 }
4562 } else {
4563 assert(purpose == GCAllocForTenured, "sanity");
4564 HeapWord* result = old_attempt_allocation(word_size);
4565 if (result != NULL) {
4566 return result;
4567 } else {
4568 // Let's try to allocate in the survivors in case we can fit the
4569 // object there.
4570 return survivor_attempt_allocation(word_size);
4571 }
4572 }
4573
4574 ShouldNotReachHere();
4575 // Trying to keep some compilers happy.
4576 return NULL;
4577 }
4578
4579 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4580 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4581
4582 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4583 : _g1h(g1h),
4584 _refs(g1h->task_queue(queue_num)),
4585 _dcq(&g1h->dirty_card_queue_set()),
4586 _ct_bs(g1h->g1_barrier_set()),
4587 _g1_rem(g1h->g1_rem_set()),
4588 _hash_seed(17), _queue_num(queue_num),
4589 _term_attempts(0),
4590 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4591 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4592 _age_table(false), _scanner(g1h, this, rp),
4593 _strong_roots_time(0), _term_time(0),
4594 _alloc_buffer_waste(0), _undo_waste(0) {
4595 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4596 // we "sacrifice" entry 0 to keep track of surviving bytes for
4597 // non-young regions (where the age is -1)
4598 // We also add a few elements at the beginning and at the end in
4599 // an attempt to eliminate cache contention
4600 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4601 uint array_length = PADDING_ELEM_NUM +
4602 real_length +
4603 PADDING_ELEM_NUM;
4604 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4605 if (_surviving_young_words_base == NULL)
4606 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4607 "Not enough space for young surv histo.");
4608 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4609 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4610
4611 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4612 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4613
4614 _start = os::elapsedTime();
4615 }
4616
4617 void
4618 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4619 {
4620 st->print_raw_cr("GC Termination Stats");
4621 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4622 " ------waste (KiB)------");
4623 st->print_raw_cr("thr ms ms % ms % attempts"
4624 " total alloc undo");
4625 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4626 " ------- ------- -------");
4627 }
4628
4629 void
4630 G1ParScanThreadState::print_termination_stats(int i,
4631 outputStream* const st) const
4632 {
4633 const double elapsed_ms = elapsed_time() * 1000.0;
4634 const double s_roots_ms = strong_roots_time() * 1000.0;
4635 const double term_ms = term_time() * 1000.0;
4636 st->print_cr("%3d %9.2f %9.2f %6.2f "
4637 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4638 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4639 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4640 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4641 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4642 alloc_buffer_waste() * HeapWordSize / K,
4643 undo_waste() * HeapWordSize / K);
4644 }
4645
4646 #ifdef ASSERT
4647 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4648 assert(ref != NULL, "invariant");
4649 assert(UseCompressedOops, "sanity");
4650 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4651 oop p = oopDesc::load_decode_heap_oop(ref);
4652 assert(_g1h->is_in_g1_reserved(p),
4653 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4654 return true;
4655 }
4656
4657 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4658 assert(ref != NULL, "invariant");
4659 if (has_partial_array_mask(ref)) {
4660 // Must be in the collection set--it's already been copied.
4661 oop p = clear_partial_array_mask(ref);
4662 assert(_g1h->obj_in_cs(p),
4663 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4664 } else {
4665 oop p = oopDesc::load_decode_heap_oop(ref);
4666 assert(_g1h->is_in_g1_reserved(p),
4667 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4668 }
4669 return true;
4670 }
4671
4672 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4673 if (ref.is_narrow()) {
4674 return verify_ref((narrowOop*) ref);
4675 } else {
4676 return verify_ref((oop*) ref);
4677 }
4678 }
4679 #endif // ASSERT
4680
4681 void G1ParScanThreadState::trim_queue() {
4682 assert(_evac_failure_cl != NULL, "not set");
4683
4684 StarTask ref;
4685 do {
4686 // Drain the overflow stack first, so other threads can steal.
4687 while (refs()->pop_overflow(ref)) {
4688 deal_with_reference(ref);
4689 }
4690
4691 while (refs()->pop_local(ref)) {
4692 deal_with_reference(ref);
4693 }
4694 } while (!refs()->is_empty());
4695 }
4696
4697 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4698 G1ParScanThreadState* par_scan_state) :
4699 _g1(g1), _par_scan_state(par_scan_state),
4700 _worker_id(par_scan_state->queue_num()) { }
4701
4702 void G1ParCopyHelper::mark_object(oop obj) {
4703 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4704
4705 // We know that the object is not moving so it's safe to read its size.
4706 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4707 }
4708
4709 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4710 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4711 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4712 assert(from_obj != to_obj, "should not be self-forwarded");
4713
4714 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4715 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4716
4717 // The object might be in the process of being copied by another
4718 // worker so we cannot trust that its to-space image is
4719 // well-formed. So we have to read its size from its from-space
4720 // image which we know should not be changing.
4721 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4722 }
4723
4724 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4725 size_t word_sz = old->size();
4726 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4727 // +1 to make the -1 indexes valid...
4728 int young_index = from_region->young_index_in_cset()+1;
4729 assert( (from_region->is_young() && young_index > 0) ||
4730 (!from_region->is_young() && young_index == 0), "invariant" );
4731 G1CollectorPolicy* g1p = _g1h->g1_policy();
4732 markOop m = old->mark();
4733 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4734 : m->age();
4735 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4736 word_sz);
4737 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4738 #ifndef PRODUCT
4739 // Should this evacuation fail?
4740 if (_g1h->evacuation_should_fail()) {
4741 if (obj_ptr != NULL) {
4742 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4743 obj_ptr = NULL;
4744 }
4745 }
4746 #endif // !PRODUCT
4747
4748 if (obj_ptr == NULL) {
4749 // This will either forward-to-self, or detect that someone else has
4750 // installed a forwarding pointer.
4751 return _g1h->handle_evacuation_failure_par(this, old);
4752 }
4753
4754 oop obj = oop(obj_ptr);
4755
4756 // We're going to allocate linearly, so might as well prefetch ahead.
4757 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4758
4759 oop forward_ptr = old->forward_to_atomic(obj);
4760 if (forward_ptr == NULL) {
4761 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4762
4763 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4764 // we actually allocated from and update alloc_purpose accordingly
4765 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4766 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4767
4768 if (g1p->track_object_age(alloc_purpose)) {
4769 // We could simply do obj->incr_age(). However, this causes a
4770 // performance issue. obj->incr_age() will first check whether
4771 // the object has a displaced mark by checking its mark word;
4772 // getting the mark word from the new location of the object
4773 // stalls. So, given that we already have the mark word and we
4774 // are about to install it anyway, it's better to increase the
4775 // age on the mark word, when the object does not have a
4776 // displaced mark word. We're not expecting many objects to have
4777 // a displaced marked word, so that case is not optimized
4778 // further (it could be...) and we simply call obj->incr_age().
4779
4780 if (m->has_displaced_mark_helper()) {
4781 // in this case, we have to install the mark word first,
4782 // otherwise obj looks to be forwarded (the old mark word,
4783 // which contains the forward pointer, was copied)
4784 obj->set_mark(m);
4785 obj->incr_age();
4786 } else {
4787 m = m->incr_age();
4788 obj->set_mark(m);
4789 }
4790 age_table()->add(obj, word_sz);
4791 } else {
4792 obj->set_mark(m);
4793 }
4794
4795 if (G1StringDedup::is_enabled()) {
4796 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4797 to_region->is_young(),
4798 queue_num(),
4799 obj);
4800 }
4801
4802 size_t* surv_young_words = surviving_young_words();
4803 surv_young_words[young_index] += word_sz;
4804
4805 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4806 // We keep track of the next start index in the length field of
4807 // the to-space object. The actual length can be found in the
4808 // length field of the from-space object.
4809 arrayOop(obj)->set_length(0);
4810 oop* old_p = set_partial_array_mask(old);
4811 push_on_queue(old_p);
4812 } else {
4813 // No point in using the slower heap_region_containing() method,
4814 // given that we know obj is in the heap.
4815 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4816 obj->oop_iterate_backwards(&_scanner);
4817 }
4818 } else {
4819 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4820 obj = forward_ptr;
4821 }
4822 return obj;
4823 }
4824
4825 template <class T>
4826 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4827 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4828 _scanned_klass->record_modified_oops();
4829 }
4830 }
4831
4832 template <G1Barrier barrier, bool do_mark_object>
4833 template <class T>
4834 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4835 T heap_oop = oopDesc::load_heap_oop(p);
4836
4837 if (oopDesc::is_null(heap_oop)) {
4838 return;
4839 }
4840
4841 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4842
4843 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4844
4845 if (_g1->in_cset_fast_test(obj)) {
4846 oop forwardee;
4847 if (obj->is_forwarded()) {
4848 forwardee = obj->forwardee();
4849 } else {
4850 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4851 }
4852 assert(forwardee != NULL, "forwardee should not be NULL");
4853 oopDesc::encode_store_heap_oop(p, forwardee);
4854 if (do_mark_object && forwardee != obj) {
4855 // If the object is self-forwarded we don't need to explicitly
4856 // mark it, the evacuation failure protocol will do so.
4857 mark_forwarded_object(obj, forwardee);
4858 }
4859
4860 if (barrier == G1BarrierKlass) {
4861 do_klass_barrier(p, forwardee);
4862 }
4863 } else {
4864 // The object is not in collection set. If we're a root scanning
4865 // closure during an initial mark pause (i.e. do_mark_object will
4866 // be true) then attempt to mark the object.
4867 if (do_mark_object) {
4868 mark_object(obj);
4869 }
4870 }
4871
4872 if (barrier == G1BarrierEvac) {
4873 _par_scan_state->update_rs(_from, p, _worker_id);
4874 }
4875 }
4876
4877 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4878 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4879
4880 class G1ParEvacuateFollowersClosure : public VoidClosure {
4881 protected:
4882 G1CollectedHeap* _g1h;
4883 G1ParScanThreadState* _par_scan_state;
4884 RefToScanQueueSet* _queues;
4885 ParallelTaskTerminator* _terminator;
4886
4887 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4888 RefToScanQueueSet* queues() { return _queues; }
4889 ParallelTaskTerminator* terminator() { return _terminator; }
4890
4891 public:
4892 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4893 G1ParScanThreadState* par_scan_state,
4894 RefToScanQueueSet* queues,
4895 ParallelTaskTerminator* terminator)
4896 : _g1h(g1h), _par_scan_state(par_scan_state),
4897 _queues(queues), _terminator(terminator) {}
4898
4899 void do_void();
4900
4901 private:
4902 inline bool offer_termination();
4903 };
4904
4905 bool G1ParEvacuateFollowersClosure::offer_termination() {
4906 G1ParScanThreadState* const pss = par_scan_state();
4907 pss->start_term_time();
4908 const bool res = terminator()->offer_termination();
4909 pss->end_term_time();
4910 return res;
4911 }
4912
4913 void G1ParEvacuateFollowersClosure::do_void() {
4914 StarTask stolen_task;
4915 G1ParScanThreadState* const pss = par_scan_state();
4916 pss->trim_queue();
4917
4918 do {
4919 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4920 assert(pss->verify_task(stolen_task), "sanity");
4921 if (stolen_task.is_narrow()) {
4922 pss->deal_with_reference((narrowOop*) stolen_task);
4923 } else {
4924 pss->deal_with_reference((oop*) stolen_task);
4925 }
4926
4927 // We've just processed a reference and we might have made
4928 // available new entries on the queues. So we have to make sure
4929 // we drain the queues as necessary.
4930 pss->trim_queue();
4931 }
4932 } while (!offer_termination());
4933 }
4934
4935 class G1KlassScanClosure : public KlassClosure {
4936 G1ParCopyHelper* _closure;
4937 bool _process_only_dirty;
4938 int _count;
4939 public:
4940 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4941 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4942 void do_klass(Klass* klass) {
4943 // If the klass has not been dirtied we know that there's
4944 // no references into the young gen and we can skip it.
4945 if (!_process_only_dirty || klass->has_modified_oops()) {
4946 // Clean the klass since we're going to scavenge all the metadata.
4947 klass->clear_modified_oops();
4948
4949 // Tell the closure that this klass is the Klass to scavenge
4950 // and is the one to dirty if oops are left pointing into the young gen.
4951 _closure->set_scanned_klass(klass);
4952
4953 klass->oops_do(_closure);
4954
4955 _closure->set_scanned_klass(NULL);
4956 }
4957 _count++;
4958 }
4959 };
4960
4961 class G1ParTask : public AbstractGangTask {
4962 protected:
4963 G1CollectedHeap* _g1h;
4964 RefToScanQueueSet *_queues;
4965 ParallelTaskTerminator _terminator;
4966 uint _n_workers;
4967
4968 Mutex _stats_lock;
4969 Mutex* stats_lock() { return &_stats_lock; }
4970
4971 size_t getNCards() {
4972 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4973 / G1BlockOffsetSharedArray::N_bytes;
4974 }
4975
4976 public:
4977 G1ParTask(G1CollectedHeap* g1h,
4978 RefToScanQueueSet *task_queues)
4979 : AbstractGangTask("G1 collection"),
4980 _g1h(g1h),
4981 _queues(task_queues),
4982 _terminator(0, _queues),
4983 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4984 {}
4985
4986 RefToScanQueueSet* queues() { return _queues; }
4987
4988 RefToScanQueue *work_queue(int i) {
4989 return queues()->queue(i);
4990 }
4991
4992 ParallelTaskTerminator* terminator() { return &_terminator; }
4993
4994 virtual void set_for_termination(int active_workers) {
4995 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4996 // in the young space (_par_seq_tasks) in the G1 heap
4997 // for SequentialSubTasksDone.
4998 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4999 // both of which need setting by set_n_termination().
5000 _g1h->SharedHeap::set_n_termination(active_workers);
5001 _g1h->set_n_termination(active_workers);
5002 terminator()->reset_for_reuse(active_workers);
5003 _n_workers = active_workers;
5004 }
5005
5006 void work(uint worker_id) {
5007 if (worker_id >= _n_workers) return; // no work needed this round
5008
5009 double start_time_ms = os::elapsedTime() * 1000.0;
5010 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5011
5012 {
5013 ResourceMark rm;
5014 HandleMark hm;
5015
5016 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5017
5018 G1ParScanThreadState pss(_g1h, worker_id, rp);
5019 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5020
5021 pss.set_evac_failure_closure(&evac_failure_cl);
5022
5023 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5024 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5025
5026 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5027 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5028
5029 bool only_young = _g1h->g1_policy()->gcs_are_young();
5030 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5031 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5032
5033 OopClosure* scan_root_cl = &only_scan_root_cl;
5034 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5035
5036 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5037 // We also need to mark copied objects.
5038 scan_root_cl = &scan_mark_root_cl;
5039 scan_klasses_cl = &scan_mark_klasses_cl_s;
5040 }
5041
5042 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5043
5044 // Don't scan the scavengable methods in the code cache as part
5045 // of strong root scanning. The code roots that point into a
5046 // region in the collection set are scanned when we scan the
5047 // region's RSet.
5048 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5049
5050 pss.start_strong_roots();
5051 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5052 SharedHeap::ScanningOption(so),
5053 scan_root_cl,
5054 &push_heap_rs_cl,
5055 scan_klasses_cl,
5056 worker_id);
5057 pss.end_strong_roots();
5058
5059 {
5060 double start = os::elapsedTime();
5061 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5062 evac.do_void();
5063 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5064 double term_ms = pss.term_time()*1000.0;
5065 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5066 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5067 }
5068 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5069 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5070
5071 if (ParallelGCVerbose) {
5072 MutexLocker x(stats_lock());
5073 pss.print_termination_stats(worker_id);
5074 }
5075
5076 assert(pss.refs()->is_empty(), "should be empty");
5077
5078 // Close the inner scope so that the ResourceMark and HandleMark
5079 // destructors are executed here and are included as part of the
5080 // "GC Worker Time".
5081 }
5082
5083 double end_time_ms = os::elapsedTime() * 1000.0;
5084 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5085 }
5086 };
5087
5088 // *** Common G1 Evacuation Stuff
5089
5090 // This method is run in a GC worker.
5091
5092 void
5093 G1CollectedHeap::
5094 g1_process_strong_roots(bool is_scavenging,
5095 ScanningOption so,
5096 OopClosure* scan_non_heap_roots,
5097 OopsInHeapRegionClosure* scan_rs,
5098 G1KlassScanClosure* scan_klasses,
5099 uint worker_i) {
5100
5101 // First scan the strong roots
5102 double ext_roots_start = os::elapsedTime();
5103 double closure_app_time_sec = 0.0;
5104
5105 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5106
5107 process_strong_roots(false, // no scoping; this is parallel code
5108 so,
5109 &buf_scan_non_heap_roots,
5110 scan_klasses
5111 );
5112
5113 // Now the CM ref_processor roots.
5114 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5115 // We need to treat the discovered reference lists of the
5116 // concurrent mark ref processor as roots and keep entries
5117 // (which are added by the marking threads) on them live
5118 // until they can be processed at the end of marking.
5119 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5120 }
5121
5122 // Finish up any enqueued closure apps (attributed as object copy time).
5123 buf_scan_non_heap_roots.done();
5124
5125 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5126
5127 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5128
5129 double ext_root_time_ms =
5130 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5131
5132 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5133
5134 // During conc marking we have to filter the per-thread SATB buffers
5135 // to make sure we remove any oops into the CSet (which will show up
5136 // as implicitly live).
5137 double satb_filtering_ms = 0.0;
5138 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5139 if (mark_in_progress()) {
5140 double satb_filter_start = os::elapsedTime();
5141
5142 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5143
5144 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5145 }
5146 }
5147 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5148
5149 // If this is an initial mark pause, and we're not scanning
5150 // the entire code cache, we need to mark the oops in the
5151 // strong code root lists for the regions that are not in
5152 // the collection set.
5153 // Note all threads participate in this set of root tasks.
5154 double mark_strong_code_roots_ms = 0.0;
5155 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5156 double mark_strong_roots_start = os::elapsedTime();
5157 mark_strong_code_roots(worker_i);
5158 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5159 }
5160 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5161
5162 // Now scan the complement of the collection set.
5163 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5164 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5165
5166 _process_strong_tasks->all_tasks_completed();
5167 }
5168
5169 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5170 private:
5171 BoolObjectClosure* _is_alive;
5172 int _initial_string_table_size;
5173 int _initial_symbol_table_size;
5174
5175 bool _process_strings;
5176 int _strings_processed;
5177 int _strings_removed;
5178
5179 bool _process_symbols;
5180 int _symbols_processed;
5181 int _symbols_removed;
5182
5183 bool _do_in_parallel;
5184 public:
5185 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5186 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5187 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5188 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5189 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5190
5191 _initial_string_table_size = StringTable::the_table()->table_size();
5192 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5193 if (process_strings) {
5194 StringTable::clear_parallel_claimed_index();
5195 }
5196 if (process_symbols) {
5197 SymbolTable::clear_parallel_claimed_index();
5198 }
5199 }
5200
5201 ~G1StringSymbolTableUnlinkTask() {
5202 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5203 err_msg("claim value %d after unlink less than initial string table size %d",
5204 StringTable::parallel_claimed_index(), _initial_string_table_size));
5205 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5206 err_msg("claim value %d after unlink less than initial symbol table size %d",
5207 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5208 }
5209
5210 void work(uint worker_id) {
5211 if (_do_in_parallel) {
5212 int strings_processed = 0;
5213 int strings_removed = 0;
5214 int symbols_processed = 0;
5215 int symbols_removed = 0;
5216 if (_process_strings) {
5217 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5218 Atomic::add(strings_processed, &_strings_processed);
5219 Atomic::add(strings_removed, &_strings_removed);
5220 }
5221 if (_process_symbols) {
5222 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5223 Atomic::add(symbols_processed, &_symbols_processed);
5224 Atomic::add(symbols_removed, &_symbols_removed);
5225 }
5226 } else {
5227 if (_process_strings) {
5228 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5229 }
5230 if (_process_symbols) {
5231 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5232 }
5233 }
5234 }
5235
5236 size_t strings_processed() const { return (size_t)_strings_processed; }
5237 size_t strings_removed() const { return (size_t)_strings_removed; }
5238
5239 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5240 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5241 };
5242
5243 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5244 bool process_strings, bool process_symbols) {
5245 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5246 _g1h->workers()->active_workers() : 1);
5247
5248 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5249 if (G1CollectedHeap::use_parallel_gc_threads()) {
5250 set_par_threads(n_workers);
5251 workers()->run_task(&g1_unlink_task);
5252 set_par_threads(0);
5253 } else {
5254 g1_unlink_task.work(0);
5255 }
5256 if (G1TraceStringSymbolTableScrubbing) {
5257 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5258 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5259 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5260 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5261 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5262 }
5263
5264 if (G1StringDedup::is_enabled()) {
5265 G1StringDedup::unlink(is_alive);
5266 }
5267 }
5268
5269 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5270 private:
5271 DirtyCardQueueSet* _queue;
5272 public:
5273 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5274
5275 virtual void work(uint worker_id) {
5276 double start_time = os::elapsedTime();
5277
5278 RedirtyLoggedCardTableEntryClosure cl;
5279 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5280 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5281 } else {
5282 _queue->apply_closure_to_all_completed_buffers(&cl);
5283 }
5284
5285 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5286 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5287 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5288 }
5289 };
5290
5291 void G1CollectedHeap::redirty_logged_cards() {
5292 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5293 double redirty_logged_cards_start = os::elapsedTime();
5294
5295 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5296 _g1h->workers()->active_workers() : 1);
5297
5298 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5299 dirty_card_queue_set().reset_for_par_iteration();
5300 if (use_parallel_gc_threads()) {
5301 set_par_threads(n_workers);
5302 workers()->run_task(&redirty_task);
5303 set_par_threads(0);
5304 } else {
5305 redirty_task.work(0);
5306 }
5307
5308 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5309 dcq.merge_bufferlists(&dirty_card_queue_set());
5310 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5311
5312 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5313 }
5314
5315 // Weak Reference Processing support
5316
5317 // An always "is_alive" closure that is used to preserve referents.
5318 // If the object is non-null then it's alive. Used in the preservation
5319 // of referent objects that are pointed to by reference objects
5320 // discovered by the CM ref processor.
5321 class G1AlwaysAliveClosure: public BoolObjectClosure {
5322 G1CollectedHeap* _g1;
5323 public:
5324 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5325 bool do_object_b(oop p) {
5326 if (p != NULL) {
5327 return true;
5328 }
5329 return false;
5330 }
5331 };
5332
5333 bool G1STWIsAliveClosure::do_object_b(oop p) {
5334 // An object is reachable if it is outside the collection set,
5335 // or is inside and copied.
5336 return !_g1->obj_in_cs(p) || p->is_forwarded();
5337 }
5338
5339 // Non Copying Keep Alive closure
5340 class G1KeepAliveClosure: public OopClosure {
5341 G1CollectedHeap* _g1;
5342 public:
5343 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5344 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5345 void do_oop( oop* p) {
5346 oop obj = *p;
5347
5348 if (_g1->obj_in_cs(obj)) {
5349 assert( obj->is_forwarded(), "invariant" );
5350 *p = obj->forwardee();
5351 }
5352 }
5353 };
5354
5355 // Copying Keep Alive closure - can be called from both
5356 // serial and parallel code as long as different worker
5357 // threads utilize different G1ParScanThreadState instances
5358 // and different queues.
5359
5360 class G1CopyingKeepAliveClosure: public OopClosure {
5361 G1CollectedHeap* _g1h;
5362 OopClosure* _copy_non_heap_obj_cl;
5363 G1ParScanThreadState* _par_scan_state;
5364
5365 public:
5366 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5367 OopClosure* non_heap_obj_cl,
5368 G1ParScanThreadState* pss):
5369 _g1h(g1h),
5370 _copy_non_heap_obj_cl(non_heap_obj_cl),
5371 _par_scan_state(pss)
5372 {}
5373
5374 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5375 virtual void do_oop( oop* p) { do_oop_work(p); }
5376
5377 template <class T> void do_oop_work(T* p) {
5378 oop obj = oopDesc::load_decode_heap_oop(p);
5379
5380 if (_g1h->obj_in_cs(obj)) {
5381 // If the referent object has been forwarded (either copied
5382 // to a new location or to itself in the event of an
5383 // evacuation failure) then we need to update the reference
5384 // field and, if both reference and referent are in the G1
5385 // heap, update the RSet for the referent.
5386 //
5387 // If the referent has not been forwarded then we have to keep
5388 // it alive by policy. Therefore we have copy the referent.
5389 //
5390 // If the reference field is in the G1 heap then we can push
5391 // on the PSS queue. When the queue is drained (after each
5392 // phase of reference processing) the object and it's followers
5393 // will be copied, the reference field set to point to the
5394 // new location, and the RSet updated. Otherwise we need to
5395 // use the the non-heap or metadata closures directly to copy
5396 // the referent object and update the pointer, while avoiding
5397 // updating the RSet.
5398
5399 if (_g1h->is_in_g1_reserved(p)) {
5400 _par_scan_state->push_on_queue(p);
5401 } else {
5402 assert(!Metaspace::contains((const void*)p),
5403 err_msg("Unexpectedly found a pointer from metadata: "
5404 PTR_FORMAT, p));
5405 _copy_non_heap_obj_cl->do_oop(p);
5406 }
5407 }
5408 }
5409 };
5410
5411 // Serial drain queue closure. Called as the 'complete_gc'
5412 // closure for each discovered list in some of the
5413 // reference processing phases.
5414
5415 class G1STWDrainQueueClosure: public VoidClosure {
5416 protected:
5417 G1CollectedHeap* _g1h;
5418 G1ParScanThreadState* _par_scan_state;
5419
5420 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5421
5422 public:
5423 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5424 _g1h(g1h),
5425 _par_scan_state(pss)
5426 { }
5427
5428 void do_void() {
5429 G1ParScanThreadState* const pss = par_scan_state();
5430 pss->trim_queue();
5431 }
5432 };
5433
5434 // Parallel Reference Processing closures
5435
5436 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5437 // processing during G1 evacuation pauses.
5438
5439 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5440 private:
5441 G1CollectedHeap* _g1h;
5442 RefToScanQueueSet* _queues;
5443 FlexibleWorkGang* _workers;
5444 int _active_workers;
5445
5446 public:
5447 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5448 FlexibleWorkGang* workers,
5449 RefToScanQueueSet *task_queues,
5450 int n_workers) :
5451 _g1h(g1h),
5452 _queues(task_queues),
5453 _workers(workers),
5454 _active_workers(n_workers)
5455 {
5456 assert(n_workers > 0, "shouldn't call this otherwise");
5457 }
5458
5459 // Executes the given task using concurrent marking worker threads.
5460 virtual void execute(ProcessTask& task);
5461 virtual void execute(EnqueueTask& task);
5462 };
5463
5464 // Gang task for possibly parallel reference processing
5465
5466 class G1STWRefProcTaskProxy: public AbstractGangTask {
5467 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5468 ProcessTask& _proc_task;
5469 G1CollectedHeap* _g1h;
5470 RefToScanQueueSet *_task_queues;
5471 ParallelTaskTerminator* _terminator;
5472
5473 public:
5474 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5475 G1CollectedHeap* g1h,
5476 RefToScanQueueSet *task_queues,
5477 ParallelTaskTerminator* terminator) :
5478 AbstractGangTask("Process reference objects in parallel"),
5479 _proc_task(proc_task),
5480 _g1h(g1h),
5481 _task_queues(task_queues),
5482 _terminator(terminator)
5483 {}
5484
5485 virtual void work(uint worker_id) {
5486 // The reference processing task executed by a single worker.
5487 ResourceMark rm;
5488 HandleMark hm;
5489
5490 G1STWIsAliveClosure is_alive(_g1h);
5491
5492 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5493 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5494
5495 pss.set_evac_failure_closure(&evac_failure_cl);
5496
5497 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5498
5499 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5500
5501 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5502
5503 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5504 // We also need to mark copied objects.
5505 copy_non_heap_cl = ©_mark_non_heap_cl;
5506 }
5507
5508 // Keep alive closure.
5509 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5510
5511 // Complete GC closure
5512 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5513
5514 // Call the reference processing task's work routine.
5515 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5516
5517 // Note we cannot assert that the refs array is empty here as not all
5518 // of the processing tasks (specifically phase2 - pp2_work) execute
5519 // the complete_gc closure (which ordinarily would drain the queue) so
5520 // the queue may not be empty.
5521 }
5522 };
5523
5524 // Driver routine for parallel reference processing.
5525 // Creates an instance of the ref processing gang
5526 // task and has the worker threads execute it.
5527 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5528 assert(_workers != NULL, "Need parallel worker threads.");
5529
5530 ParallelTaskTerminator terminator(_active_workers, _queues);
5531 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5532
5533 _g1h->set_par_threads(_active_workers);
5534 _workers->run_task(&proc_task_proxy);
5535 _g1h->set_par_threads(0);
5536 }
5537
5538 // Gang task for parallel reference enqueueing.
5539
5540 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5541 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5542 EnqueueTask& _enq_task;
5543
5544 public:
5545 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5546 AbstractGangTask("Enqueue reference objects in parallel"),
5547 _enq_task(enq_task)
5548 { }
5549
5550 virtual void work(uint worker_id) {
5551 _enq_task.work(worker_id);
5552 }
5553 };
5554
5555 // Driver routine for parallel reference enqueueing.
5556 // Creates an instance of the ref enqueueing gang
5557 // task and has the worker threads execute it.
5558
5559 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5560 assert(_workers != NULL, "Need parallel worker threads.");
5561
5562 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5563
5564 _g1h->set_par_threads(_active_workers);
5565 _workers->run_task(&enq_task_proxy);
5566 _g1h->set_par_threads(0);
5567 }
5568
5569 // End of weak reference support closures
5570
5571 // Abstract task used to preserve (i.e. copy) any referent objects
5572 // that are in the collection set and are pointed to by reference
5573 // objects discovered by the CM ref processor.
5574
5575 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5576 protected:
5577 G1CollectedHeap* _g1h;
5578 RefToScanQueueSet *_queues;
5579 ParallelTaskTerminator _terminator;
5580 uint _n_workers;
5581
5582 public:
5583 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5584 AbstractGangTask("ParPreserveCMReferents"),
5585 _g1h(g1h),
5586 _queues(task_queues),
5587 _terminator(workers, _queues),
5588 _n_workers(workers)
5589 { }
5590
5591 void work(uint worker_id) {
5592 ResourceMark rm;
5593 HandleMark hm;
5594
5595 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5596 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5597
5598 pss.set_evac_failure_closure(&evac_failure_cl);
5599
5600 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5601
5602
5603 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5604
5605 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5606
5607 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5608
5609 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5610 // We also need to mark copied objects.
5611 copy_non_heap_cl = ©_mark_non_heap_cl;
5612 }
5613
5614 // Is alive closure
5615 G1AlwaysAliveClosure always_alive(_g1h);
5616
5617 // Copying keep alive closure. Applied to referent objects that need
5618 // to be copied.
5619 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5620
5621 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5622
5623 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5624 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5625
5626 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5627 // So this must be true - but assert just in case someone decides to
5628 // change the worker ids.
5629 assert(0 <= worker_id && worker_id < limit, "sanity");
5630 assert(!rp->discovery_is_atomic(), "check this code");
5631
5632 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5633 for (uint idx = worker_id; idx < limit; idx += stride) {
5634 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5635
5636 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5637 while (iter.has_next()) {
5638 // Since discovery is not atomic for the CM ref processor, we
5639 // can see some null referent objects.
5640 iter.load_ptrs(DEBUG_ONLY(true));
5641 oop ref = iter.obj();
5642
5643 // This will filter nulls.
5644 if (iter.is_referent_alive()) {
5645 iter.make_referent_alive();
5646 }
5647 iter.move_to_next();
5648 }
5649 }
5650
5651 // Drain the queue - which may cause stealing
5652 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5653 drain_queue.do_void();
5654 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5655 assert(pss.refs()->is_empty(), "should be");
5656 }
5657 };
5658
5659 // Weak Reference processing during an evacuation pause (part 1).
5660 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5661 double ref_proc_start = os::elapsedTime();
5662
5663 ReferenceProcessor* rp = _ref_processor_stw;
5664 assert(rp->discovery_enabled(), "should have been enabled");
5665
5666 // Any reference objects, in the collection set, that were 'discovered'
5667 // by the CM ref processor should have already been copied (either by
5668 // applying the external root copy closure to the discovered lists, or
5669 // by following an RSet entry).
5670 //
5671 // But some of the referents, that are in the collection set, that these
5672 // reference objects point to may not have been copied: the STW ref
5673 // processor would have seen that the reference object had already
5674 // been 'discovered' and would have skipped discovering the reference,
5675 // but would not have treated the reference object as a regular oop.
5676 // As a result the copy closure would not have been applied to the
5677 // referent object.
5678 //
5679 // We need to explicitly copy these referent objects - the references
5680 // will be processed at the end of remarking.
5681 //
5682 // We also need to do this copying before we process the reference
5683 // objects discovered by the STW ref processor in case one of these
5684 // referents points to another object which is also referenced by an
5685 // object discovered by the STW ref processor.
5686
5687 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5688 no_of_gc_workers == workers()->active_workers(),
5689 "Need to reset active GC workers");
5690
5691 set_par_threads(no_of_gc_workers);
5692 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5693 no_of_gc_workers,
5694 _task_queues);
5695
5696 if (G1CollectedHeap::use_parallel_gc_threads()) {
5697 workers()->run_task(&keep_cm_referents);
5698 } else {
5699 keep_cm_referents.work(0);
5700 }
5701
5702 set_par_threads(0);
5703
5704 // Closure to test whether a referent is alive.
5705 G1STWIsAliveClosure is_alive(this);
5706
5707 // Even when parallel reference processing is enabled, the processing
5708 // of JNI refs is serial and performed serially by the current thread
5709 // rather than by a worker. The following PSS will be used for processing
5710 // JNI refs.
5711
5712 // Use only a single queue for this PSS.
5713 G1ParScanThreadState pss(this, 0, NULL);
5714
5715 // We do not embed a reference processor in the copying/scanning
5716 // closures while we're actually processing the discovered
5717 // reference objects.
5718 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5719
5720 pss.set_evac_failure_closure(&evac_failure_cl);
5721
5722 assert(pss.refs()->is_empty(), "pre-condition");
5723
5724 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5725
5726 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5727
5728 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5729
5730 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5731 // We also need to mark copied objects.
5732 copy_non_heap_cl = ©_mark_non_heap_cl;
5733 }
5734
5735 // Keep alive closure.
5736 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5737
5738 // Serial Complete GC closure
5739 G1STWDrainQueueClosure drain_queue(this, &pss);
5740
5741 // Setup the soft refs policy...
5742 rp->setup_policy(false);
5743
5744 ReferenceProcessorStats stats;
5745 if (!rp->processing_is_mt()) {
5746 // Serial reference processing...
5747 stats = rp->process_discovered_references(&is_alive,
5748 &keep_alive,
5749 &drain_queue,
5750 NULL,
5751 _gc_timer_stw);
5752 } else {
5753 // Parallel reference processing
5754 assert(rp->num_q() == no_of_gc_workers, "sanity");
5755 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5756
5757 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5758 stats = rp->process_discovered_references(&is_alive,
5759 &keep_alive,
5760 &drain_queue,
5761 &par_task_executor,
5762 _gc_timer_stw);
5763 }
5764
5765 _gc_tracer_stw->report_gc_reference_stats(stats);
5766
5767 // We have completed copying any necessary live referent objects.
5768 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5769
5770 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5771 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5772 }
5773
5774 // Weak Reference processing during an evacuation pause (part 2).
5775 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5776 double ref_enq_start = os::elapsedTime();
5777
5778 ReferenceProcessor* rp = _ref_processor_stw;
5779 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5780
5781 // Now enqueue any remaining on the discovered lists on to
5782 // the pending list.
5783 if (!rp->processing_is_mt()) {
5784 // Serial reference processing...
5785 rp->enqueue_discovered_references();
5786 } else {
5787 // Parallel reference enqueueing
5788
5789 assert(no_of_gc_workers == workers()->active_workers(),
5790 "Need to reset active workers");
5791 assert(rp->num_q() == no_of_gc_workers, "sanity");
5792 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5793
5794 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5795 rp->enqueue_discovered_references(&par_task_executor);
5796 }
5797
5798 rp->verify_no_references_recorded();
5799 assert(!rp->discovery_enabled(), "should have been disabled");
5800
5801 // FIXME
5802 // CM's reference processing also cleans up the string and symbol tables.
5803 // Should we do that here also? We could, but it is a serial operation
5804 // and could significantly increase the pause time.
5805
5806 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5807 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5808 }
5809
5810 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5811 _expand_heap_after_alloc_failure = true;
5812 _evacuation_failed = false;
5813
5814 // Should G1EvacuationFailureALot be in effect for this GC?
5815 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5816
5817 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5818
5819 // Disable the hot card cache.
5820 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5821 hot_card_cache->reset_hot_cache_claimed_index();
5822 hot_card_cache->set_use_cache(false);
5823
5824 uint n_workers;
5825 if (G1CollectedHeap::use_parallel_gc_threads()) {
5826 n_workers =
5827 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5828 workers()->active_workers(),
5829 Threads::number_of_non_daemon_threads());
5830 assert(UseDynamicNumberOfGCThreads ||
5831 n_workers == workers()->total_workers(),
5832 "If not dynamic should be using all the workers");
5833 workers()->set_active_workers(n_workers);
5834 set_par_threads(n_workers);
5835 } else {
5836 assert(n_par_threads() == 0,
5837 "Should be the original non-parallel value");
5838 n_workers = 1;
5839 }
5840
5841 G1ParTask g1_par_task(this, _task_queues);
5842
5843 init_for_evac_failure(NULL);
5844
5845 rem_set()->prepare_for_younger_refs_iterate(true);
5846
5847 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5848 double start_par_time_sec = os::elapsedTime();
5849 double end_par_time_sec;
5850
5851 {
5852 StrongRootsScope srs(this);
5853
5854 if (G1CollectedHeap::use_parallel_gc_threads()) {
5855 // The individual threads will set their evac-failure closures.
5856 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5857 // These tasks use ShareHeap::_process_strong_tasks
5858 assert(UseDynamicNumberOfGCThreads ||
5859 workers()->active_workers() == workers()->total_workers(),
5860 "If not dynamic should be using all the workers");
5861 workers()->run_task(&g1_par_task);
5862 } else {
5863 g1_par_task.set_for_termination(n_workers);
5864 g1_par_task.work(0);
5865 }
5866 end_par_time_sec = os::elapsedTime();
5867
5868 // Closing the inner scope will execute the destructor
5869 // for the StrongRootsScope object. We record the current
5870 // elapsed time before closing the scope so that time
5871 // taken for the SRS destructor is NOT included in the
5872 // reported parallel time.
5873 }
5874
5875 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5876 g1_policy()->phase_times()->record_par_time(par_time_ms);
5877
5878 double code_root_fixup_time_ms =
5879 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5880 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5881
5882 set_par_threads(0);
5883
5884 // Process any discovered reference objects - we have
5885 // to do this _before_ we retire the GC alloc regions
5886 // as we may have to copy some 'reachable' referent
5887 // objects (and their reachable sub-graphs) that were
5888 // not copied during the pause.
5889 process_discovered_references(n_workers);
5890
5891 // Weak root processing.
5892 {
5893 G1STWIsAliveClosure is_alive(this);
5894 G1KeepAliveClosure keep_alive(this);
5895 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5896 if (G1StringDedup::is_enabled()) {
5897 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5898 }
5899 }
5900
5901 release_gc_alloc_regions(n_workers, evacuation_info);
5902 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5903
5904 // Reset and re-enable the hot card cache.
5905 // Note the counts for the cards in the regions in the
5906 // collection set are reset when the collection set is freed.
5907 hot_card_cache->reset_hot_cache();
5908 hot_card_cache->set_use_cache(true);
5909
5910 // Migrate the strong code roots attached to each region in
5911 // the collection set. Ideally we would like to do this
5912 // after we have finished the scanning/evacuation of the
5913 // strong code roots for a particular heap region.
5914 migrate_strong_code_roots();
5915
5916 purge_code_root_memory();
5917
5918 if (g1_policy()->during_initial_mark_pause()) {
5919 // Reset the claim values set during marking the strong code roots
5920 reset_heap_region_claim_values();
5921 }
5922
5923 finalize_for_evac_failure();
5924
5925 if (evacuation_failed()) {
5926 remove_self_forwarding_pointers();
5927
5928 // Reset the G1EvacuationFailureALot counters and flags
5929 // Note: the values are reset only when an actual
5930 // evacuation failure occurs.
5931 NOT_PRODUCT(reset_evacuation_should_fail();)
5932 }
5933
5934 // Enqueue any remaining references remaining on the STW
5935 // reference processor's discovered lists. We need to do
5936 // this after the card table is cleaned (and verified) as
5937 // the act of enqueueing entries on to the pending list
5938 // will log these updates (and dirty their associated
5939 // cards). We need these updates logged to update any
5940 // RSets.
5941 enqueue_discovered_references(n_workers);
5942
5943 if (G1DeferredRSUpdate) {
5944 redirty_logged_cards();
5945 }
5946 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5947 }
5948
5949 void G1CollectedHeap::free_region(HeapRegion* hr,
5950 FreeRegionList* free_list,
5951 bool par,
5952 bool locked) {
5953 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5954 assert(!hr->is_empty(), "the region should not be empty");
5955 assert(free_list != NULL, "pre-condition");
5956
5957 if (G1VerifyBitmaps) {
5958 MemRegion mr(hr->bottom(), hr->end());
5959 concurrent_mark()->clearRangePrevBitmap(mr);
5960 }
5961
5962 // Clear the card counts for this region.
5963 // Note: we only need to do this if the region is not young
5964 // (since we don't refine cards in young regions).
5965 if (!hr->is_young()) {
5966 _cg1r->hot_card_cache()->reset_card_counts(hr);
5967 }
5968 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5969 free_list->add_ordered(hr);
5970 }
5971
5972 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5973 FreeRegionList* free_list,
5974 bool par) {
5975 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5976 assert(free_list != NULL, "pre-condition");
5977
5978 size_t hr_capacity = hr->capacity();
5979 // We need to read this before we make the region non-humongous,
5980 // otherwise the information will be gone.
5981 uint last_index = hr->last_hc_index();
5982 hr->set_notHumongous();
5983 free_region(hr, free_list, par);
5984
5985 uint i = hr->hrs_index() + 1;
5986 while (i < last_index) {
5987 HeapRegion* curr_hr = region_at(i);
5988 assert(curr_hr->continuesHumongous(), "invariant");
5989 curr_hr->set_notHumongous();
5990 free_region(curr_hr, free_list, par);
5991 i += 1;
5992 }
5993 }
5994
5995 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5996 const HeapRegionSetCount& humongous_regions_removed) {
5997 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5998 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5999 _old_set.bulk_remove(old_regions_removed);
6000 _humongous_set.bulk_remove(humongous_regions_removed);
6001 }
6002
6003 }
6004
6005 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6006 assert(list != NULL, "list can't be null");
6007 if (!list->is_empty()) {
6008 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6009 _free_list.add_ordered(list);
6010 }
6011 }
6012
6013 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6014 assert(_summary_bytes_used >= bytes,
6015 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6016 _summary_bytes_used, bytes));
6017 _summary_bytes_used -= bytes;
6018 }
6019
6020 class G1ParCleanupCTTask : public AbstractGangTask {
6021 G1SATBCardTableModRefBS* _ct_bs;
6022 G1CollectedHeap* _g1h;
6023 HeapRegion* volatile _su_head;
6024 public:
6025 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6026 G1CollectedHeap* g1h) :
6027 AbstractGangTask("G1 Par Cleanup CT Task"),
6028 _ct_bs(ct_bs), _g1h(g1h) { }
6029
6030 void work(uint worker_id) {
6031 HeapRegion* r;
6032 while (r = _g1h->pop_dirty_cards_region()) {
6033 clear_cards(r);
6034 }
6035 }
6036
6037 void clear_cards(HeapRegion* r) {
6038 // Cards of the survivors should have already been dirtied.
6039 if (!r->is_survivor()) {
6040 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6041 }
6042 }
6043 };
6044
6045 #ifndef PRODUCT
6046 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6047 G1CollectedHeap* _g1h;
6048 G1SATBCardTableModRefBS* _ct_bs;
6049 public:
6050 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6051 : _g1h(g1h), _ct_bs(ct_bs) { }
6052 virtual bool doHeapRegion(HeapRegion* r) {
6053 if (r->is_survivor()) {
6054 _g1h->verify_dirty_region(r);
6055 } else {
6056 _g1h->verify_not_dirty_region(r);
6057 }
6058 return false;
6059 }
6060 };
6061
6062 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6063 // All of the region should be clean.
6064 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6065 MemRegion mr(hr->bottom(), hr->end());
6066 ct_bs->verify_not_dirty_region(mr);
6067 }
6068
6069 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6070 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6071 // dirty allocated blocks as they allocate them. The thread that
6072 // retires each region and replaces it with a new one will do a
6073 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6074 // not dirty that area (one less thing to have to do while holding
6075 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6076 // is dirty.
6077 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6078 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6079 if (hr->is_young()) {
6080 ct_bs->verify_g1_young_region(mr);
6081 } else {
6082 ct_bs->verify_dirty_region(mr);
6083 }
6084 }
6085
6086 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6087 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6088 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6089 verify_dirty_region(hr);
6090 }
6091 }
6092
6093 void G1CollectedHeap::verify_dirty_young_regions() {
6094 verify_dirty_young_list(_young_list->first_region());
6095 }
6096
6097 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6098 HeapWord* tams, HeapWord* end) {
6099 guarantee(tams <= end,
6100 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6101 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6102 if (result < end) {
6103 gclog_or_tty->cr();
6104 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6105 bitmap_name, result);
6106 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6107 bitmap_name, tams, end);
6108 return false;
6109 }
6110 return true;
6111 }
6112
6113 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6114 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6115 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6116
6117 HeapWord* bottom = hr->bottom();
6118 HeapWord* ptams = hr->prev_top_at_mark_start();
6119 HeapWord* ntams = hr->next_top_at_mark_start();
6120 HeapWord* end = hr->end();
6121
6122 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6123
6124 bool res_n = true;
6125 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6126 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6127 // if we happen to be in that state.
6128 if (mark_in_progress() || !_cmThread->in_progress()) {
6129 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6130 }
6131 if (!res_p || !res_n) {
6132 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6133 HR_FORMAT_PARAMS(hr));
6134 gclog_or_tty->print_cr("#### Caller: %s", caller);
6135 return false;
6136 }
6137 return true;
6138 }
6139
6140 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6141 if (!G1VerifyBitmaps) return;
6142
6143 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6144 }
6145
6146 class G1VerifyBitmapClosure : public HeapRegionClosure {
6147 private:
6148 const char* _caller;
6149 G1CollectedHeap* _g1h;
6150 bool _failures;
6151
6152 public:
6153 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6154 _caller(caller), _g1h(g1h), _failures(false) { }
6155
6156 bool failures() { return _failures; }
6157
6158 virtual bool doHeapRegion(HeapRegion* hr) {
6159 if (hr->continuesHumongous()) return false;
6160
6161 bool result = _g1h->verify_bitmaps(_caller, hr);
6162 if (!result) {
6163 _failures = true;
6164 }
6165 return false;
6166 }
6167 };
6168
6169 void G1CollectedHeap::check_bitmaps(const char* caller) {
6170 if (!G1VerifyBitmaps) return;
6171
6172 G1VerifyBitmapClosure cl(caller, this);
6173 heap_region_iterate(&cl);
6174 guarantee(!cl.failures(), "bitmap verification");
6175 }
6176 #endif // PRODUCT
6177
6178 void G1CollectedHeap::cleanUpCardTable() {
6179 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6180 double start = os::elapsedTime();
6181
6182 {
6183 // Iterate over the dirty cards region list.
6184 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6185
6186 if (G1CollectedHeap::use_parallel_gc_threads()) {
6187 set_par_threads();
6188 workers()->run_task(&cleanup_task);
6189 set_par_threads(0);
6190 } else {
6191 while (_dirty_cards_region_list) {
6192 HeapRegion* r = _dirty_cards_region_list;
6193 cleanup_task.clear_cards(r);
6194 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6195 if (_dirty_cards_region_list == r) {
6196 // The last region.
6197 _dirty_cards_region_list = NULL;
6198 }
6199 r->set_next_dirty_cards_region(NULL);
6200 }
6201 }
6202 #ifndef PRODUCT
6203 if (G1VerifyCTCleanup || VerifyAfterGC) {
6204 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6205 heap_region_iterate(&cleanup_verifier);
6206 }
6207 #endif
6208 }
6209
6210 double elapsed = os::elapsedTime() - start;
6211 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6212 }
6213
6214 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6215 size_t pre_used = 0;
6216 FreeRegionList local_free_list("Local List for CSet Freeing");
6217
6218 double young_time_ms = 0.0;
6219 double non_young_time_ms = 0.0;
6220
6221 // Since the collection set is a superset of the the young list,
6222 // all we need to do to clear the young list is clear its
6223 // head and length, and unlink any young regions in the code below
6224 _young_list->clear();
6225
6226 G1CollectorPolicy* policy = g1_policy();
6227
6228 double start_sec = os::elapsedTime();
6229 bool non_young = true;
6230
6231 HeapRegion* cur = cs_head;
6232 int age_bound = -1;
6233 size_t rs_lengths = 0;
6234
6235 while (cur != NULL) {
6236 assert(!is_on_master_free_list(cur), "sanity");
6237 if (non_young) {
6238 if (cur->is_young()) {
6239 double end_sec = os::elapsedTime();
6240 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6241 non_young_time_ms += elapsed_ms;
6242
6243 start_sec = os::elapsedTime();
6244 non_young = false;
6245 }
6246 } else {
6247 if (!cur->is_young()) {
6248 double end_sec = os::elapsedTime();
6249 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6250 young_time_ms += elapsed_ms;
6251
6252 start_sec = os::elapsedTime();
6253 non_young = true;
6254 }
6255 }
6256
6257 rs_lengths += cur->rem_set()->occupied_locked();
6258
6259 HeapRegion* next = cur->next_in_collection_set();
6260 assert(cur->in_collection_set(), "bad CS");
6261 cur->set_next_in_collection_set(NULL);
6262 cur->set_in_collection_set(false);
6263
6264 if (cur->is_young()) {
6265 int index = cur->young_index_in_cset();
6266 assert(index != -1, "invariant");
6267 assert((uint) index < policy->young_cset_region_length(), "invariant");
6268 size_t words_survived = _surviving_young_words[index];
6269 cur->record_surv_words_in_group(words_survived);
6270
6271 // At this point the we have 'popped' cur from the collection set
6272 // (linked via next_in_collection_set()) but it is still in the
6273 // young list (linked via next_young_region()). Clear the
6274 // _next_young_region field.
6275 cur->set_next_young_region(NULL);
6276 } else {
6277 int index = cur->young_index_in_cset();
6278 assert(index == -1, "invariant");
6279 }
6280
6281 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6282 (!cur->is_young() && cur->young_index_in_cset() == -1),
6283 "invariant" );
6284
6285 if (!cur->evacuation_failed()) {
6286 MemRegion used_mr = cur->used_region();
6287
6288 // And the region is empty.
6289 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6290 pre_used += cur->used();
6291 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6292 } else {
6293 cur->uninstall_surv_rate_group();
6294 if (cur->is_young()) {
6295 cur->set_young_index_in_cset(-1);
6296 }
6297 cur->set_not_young();
6298 cur->set_evacuation_failed(false);
6299 // The region is now considered to be old.
6300 _old_set.add(cur);
6301 evacuation_info.increment_collectionset_used_after(cur->used());
6302 }
6303 cur = next;
6304 }
6305
6306 evacuation_info.set_regions_freed(local_free_list.length());
6307 policy->record_max_rs_lengths(rs_lengths);
6308 policy->cset_regions_freed();
6309
6310 double end_sec = os::elapsedTime();
6311 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6312
6313 if (non_young) {
6314 non_young_time_ms += elapsed_ms;
6315 } else {
6316 young_time_ms += elapsed_ms;
6317 }
6318
6319 prepend_to_freelist(&local_free_list);
6320 decrement_summary_bytes(pre_used);
6321 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6322 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6323 }
6324
6325 // This routine is similar to the above but does not record
6326 // any policy statistics or update free lists; we are abandoning
6327 // the current incremental collection set in preparation of a
6328 // full collection. After the full GC we will start to build up
6329 // the incremental collection set again.
6330 // This is only called when we're doing a full collection
6331 // and is immediately followed by the tearing down of the young list.
6332
6333 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6334 HeapRegion* cur = cs_head;
6335
6336 while (cur != NULL) {
6337 HeapRegion* next = cur->next_in_collection_set();
6338 assert(cur->in_collection_set(), "bad CS");
6339 cur->set_next_in_collection_set(NULL);
6340 cur->set_in_collection_set(false);
6341 cur->set_young_index_in_cset(-1);
6342 cur = next;
6343 }
6344 }
6345
6346 void G1CollectedHeap::set_free_regions_coming() {
6347 if (G1ConcRegionFreeingVerbose) {
6348 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6349 "setting free regions coming");
6350 }
6351
6352 assert(!free_regions_coming(), "pre-condition");
6353 _free_regions_coming = true;
6354 }
6355
6356 void G1CollectedHeap::reset_free_regions_coming() {
6357 assert(free_regions_coming(), "pre-condition");
6358
6359 {
6360 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6361 _free_regions_coming = false;
6362 SecondaryFreeList_lock->notify_all();
6363 }
6364
6365 if (G1ConcRegionFreeingVerbose) {
6366 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6367 "reset free regions coming");
6368 }
6369 }
6370
6371 void G1CollectedHeap::wait_while_free_regions_coming() {
6372 // Most of the time we won't have to wait, so let's do a quick test
6373 // first before we take the lock.
6374 if (!free_regions_coming()) {
6375 return;
6376 }
6377
6378 if (G1ConcRegionFreeingVerbose) {
6379 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6380 "waiting for free regions");
6381 }
6382
6383 {
6384 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6385 while (free_regions_coming()) {
6386 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6387 }
6388 }
6389
6390 if (G1ConcRegionFreeingVerbose) {
6391 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6392 "done waiting for free regions");
6393 }
6394 }
6395
6396 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6397 assert(heap_lock_held_for_gc(),
6398 "the heap lock should already be held by or for this thread");
6399 _young_list->push_region(hr);
6400 }
6401
6402 class NoYoungRegionsClosure: public HeapRegionClosure {
6403 private:
6404 bool _success;
6405 public:
6406 NoYoungRegionsClosure() : _success(true) { }
6407 bool doHeapRegion(HeapRegion* r) {
6408 if (r->is_young()) {
6409 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6410 r->bottom(), r->end());
6411 _success = false;
6412 }
6413 return false;
6414 }
6415 bool success() { return _success; }
6416 };
6417
6418 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6419 bool ret = _young_list->check_list_empty(check_sample);
6420
6421 if (check_heap) {
6422 NoYoungRegionsClosure closure;
6423 heap_region_iterate(&closure);
6424 ret = ret && closure.success();
6425 }
6426
6427 return ret;
6428 }
6429
6430 class TearDownRegionSetsClosure : public HeapRegionClosure {
6431 private:
6432 HeapRegionSet *_old_set;
6433
6434 public:
6435 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6436
6437 bool doHeapRegion(HeapRegion* r) {
6438 if (r->is_empty()) {
6439 // We ignore empty regions, we'll empty the free list afterwards
6440 } else if (r->is_young()) {
6441 // We ignore young regions, we'll empty the young list afterwards
6442 } else if (r->isHumongous()) {
6443 // We ignore humongous regions, we're not tearing down the
6444 // humongous region set
6445 } else {
6446 // The rest should be old
6447 _old_set->remove(r);
6448 }
6449 return false;
6450 }
6451
6452 ~TearDownRegionSetsClosure() {
6453 assert(_old_set->is_empty(), "post-condition");
6454 }
6455 };
6456
6457 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6458 assert_at_safepoint(true /* should_be_vm_thread */);
6459
6460 if (!free_list_only) {
6461 TearDownRegionSetsClosure cl(&_old_set);
6462 heap_region_iterate(&cl);
6463
6464 // Note that emptying the _young_list is postponed and instead done as
6465 // the first step when rebuilding the regions sets again. The reason for
6466 // this is that during a full GC string deduplication needs to know if
6467 // a collected region was young or old when the full GC was initiated.
6468 }
6469 _free_list.remove_all();
6470 }
6471
6472 class RebuildRegionSetsClosure : public HeapRegionClosure {
6473 private:
6474 bool _free_list_only;
6475 HeapRegionSet* _old_set;
6476 FreeRegionList* _free_list;
6477 size_t _total_used;
6478
6479 public:
6480 RebuildRegionSetsClosure(bool free_list_only,
6481 HeapRegionSet* old_set, FreeRegionList* free_list) :
6482 _free_list_only(free_list_only),
6483 _old_set(old_set), _free_list(free_list), _total_used(0) {
6484 assert(_free_list->is_empty(), "pre-condition");
6485 if (!free_list_only) {
6486 assert(_old_set->is_empty(), "pre-condition");
6487 }
6488 }
6489
6490 bool doHeapRegion(HeapRegion* r) {
6491 if (r->continuesHumongous()) {
6492 return false;
6493 }
6494
6495 if (r->is_empty()) {
6496 // Add free regions to the free list
6497 _free_list->add_as_tail(r);
6498 } else if (!_free_list_only) {
6499 assert(!r->is_young(), "we should not come across young regions");
6500
6501 if (r->isHumongous()) {
6502 // We ignore humongous regions, we left the humongous set unchanged
6503 } else {
6504 // The rest should be old, add them to the old set
6505 _old_set->add(r);
6506 }
6507 _total_used += r->used();
6508 }
6509
6510 return false;
6511 }
6512
6513 size_t total_used() {
6514 return _total_used;
6515 }
6516 };
6517
6518 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6519 assert_at_safepoint(true /* should_be_vm_thread */);
6520
6521 if (!free_list_only) {
6522 _young_list->empty_list();
6523 }
6524
6525 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6526 heap_region_iterate(&cl);
6527
6528 if (!free_list_only) {
6529 _summary_bytes_used = cl.total_used();
6530 }
6531 assert(_summary_bytes_used == recalculate_used(),
6532 err_msg("inconsistent _summary_bytes_used, "
6533 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6534 _summary_bytes_used, recalculate_used()));
6535 }
6536
6537 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6538 _refine_cte_cl->set_concurrent(concurrent);
6539 }
6540
6541 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6542 HeapRegion* hr = heap_region_containing(p);
6543 return hr->is_in(p);
6544 }
6545
6546 // Methods for the mutator alloc region
6547
6548 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6549 bool force) {
6550 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6551 assert(!force || g1_policy()->can_expand_young_list(),
6552 "if force is true we should be able to expand the young list");
6553 bool young_list_full = g1_policy()->is_young_list_full();
6554 if (force || !young_list_full) {
6555 HeapRegion* new_alloc_region = new_region(word_size,
6556 false /* is_old */,
6557 false /* do_expand */);
6558 if (new_alloc_region != NULL) {
6559 set_region_short_lived_locked(new_alloc_region);
6560 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6561 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6562 return new_alloc_region;
6563 }
6564 }
6565 return NULL;
6566 }
6567
6568 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6569 size_t allocated_bytes) {
6570 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6571 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6572
6573 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6574 _summary_bytes_used += allocated_bytes;
6575 _hr_printer.retire(alloc_region);
6576 // We update the eden sizes here, when the region is retired,
6577 // instead of when it's allocated, since this is the point that its
6578 // used space has been recored in _summary_bytes_used.
6579 g1mm()->update_eden_size();
6580 }
6581
6582 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6583 bool force) {
6584 return _g1h->new_mutator_alloc_region(word_size, force);
6585 }
6586
6587 void G1CollectedHeap::set_par_threads() {
6588 // Don't change the number of workers. Use the value previously set
6589 // in the workgroup.
6590 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6591 uint n_workers = workers()->active_workers();
6592 assert(UseDynamicNumberOfGCThreads ||
6593 n_workers == workers()->total_workers(),
6594 "Otherwise should be using the total number of workers");
6595 if (n_workers == 0) {
6596 assert(false, "Should have been set in prior evacuation pause.");
6597 n_workers = ParallelGCThreads;
6598 workers()->set_active_workers(n_workers);
6599 }
6600 set_par_threads(n_workers);
6601 }
6602
6603 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6604 size_t allocated_bytes) {
6605 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6606 }
6607
6608 // Methods for the GC alloc regions
6609
6610 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6611 uint count,
6612 GCAllocPurpose ap) {
6613 assert(FreeList_lock->owned_by_self(), "pre-condition");
6614
6615 if (count < g1_policy()->max_regions(ap)) {
6616 bool survivor = (ap == GCAllocForSurvived);
6617 HeapRegion* new_alloc_region = new_region(word_size,
6618 !survivor,
6619 true /* do_expand */);
6620 if (new_alloc_region != NULL) {
6621 // We really only need to do this for old regions given that we
6622 // should never scan survivors. But it doesn't hurt to do it
6623 // for survivors too.
6624 new_alloc_region->set_saved_mark();
6625 if (survivor) {
6626 new_alloc_region->set_survivor();
6627 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6628 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6629 } else {
6630 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6631 check_bitmaps("Old Region Allocation", new_alloc_region);
6632 }
6633 bool during_im = g1_policy()->during_initial_mark_pause();
6634 new_alloc_region->note_start_of_copying(during_im);
6635 return new_alloc_region;
6636 } else {
6637 g1_policy()->note_alloc_region_limit_reached(ap);
6638 }
6639 }
6640 return NULL;
6641 }
6642
6643 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6644 size_t allocated_bytes,
6645 GCAllocPurpose ap) {
6646 bool during_im = g1_policy()->during_initial_mark_pause();
6647 alloc_region->note_end_of_copying(during_im);
6648 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6649 if (ap == GCAllocForSurvived) {
6650 young_list()->add_survivor_region(alloc_region);
6651 } else {
6652 _old_set.add(alloc_region);
6653 }
6654 _hr_printer.retire(alloc_region);
6655 }
6656
6657 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6658 bool force) {
6659 assert(!force, "not supported for GC alloc regions");
6660 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6661 }
6662
6663 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6664 size_t allocated_bytes) {
6665 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6666 GCAllocForSurvived);
6667 }
6668
6669 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6670 bool force) {
6671 assert(!force, "not supported for GC alloc regions");
6672 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6673 }
6674
6675 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6676 size_t allocated_bytes) {
6677 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6678 GCAllocForTenured);
6679 }
6680 // Heap region set verification
6681
6682 class VerifyRegionListsClosure : public HeapRegionClosure {
6683 private:
6684 HeapRegionSet* _old_set;
6685 HeapRegionSet* _humongous_set;
6686 FreeRegionList* _free_list;
6687
6688 public:
6689 HeapRegionSetCount _old_count;
6690 HeapRegionSetCount _humongous_count;
6691 HeapRegionSetCount _free_count;
6692
6693 VerifyRegionListsClosure(HeapRegionSet* old_set,
6694 HeapRegionSet* humongous_set,
6695 FreeRegionList* free_list) :
6696 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6697 _old_count(), _humongous_count(), _free_count(){ }
6698
6699 bool doHeapRegion(HeapRegion* hr) {
6700 if (hr->continuesHumongous()) {
6701 return false;
6702 }
6703
6704 if (hr->is_young()) {
6705 // TODO
6706 } else if (hr->startsHumongous()) {
6707 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6708 _humongous_count.increment(1u, hr->capacity());
6709 } else if (hr->is_empty()) {
6710 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6711 _free_count.increment(1u, hr->capacity());
6712 } else {
6713 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6714 _old_count.increment(1u, hr->capacity());
6715 }
6716 return false;
6717 }
6718
6719 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6720 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6721 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6722 old_set->total_capacity_bytes(), _old_count.capacity()));
6723
6724 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6725 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6726 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6727
6728 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6729 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6730 free_list->total_capacity_bytes(), _free_count.capacity()));
6731 }
6732 };
6733
6734 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6735 HeapWord* bottom) {
6736 HeapWord* end = bottom + HeapRegion::GrainWords;
6737 MemRegion mr(bottom, end);
6738 assert(_g1_reserved.contains(mr), "invariant");
6739 // This might return NULL if the allocation fails
6740 return new HeapRegion(hrs_index, _bot_shared, mr);
6741 }
6742
6743 void G1CollectedHeap::verify_region_sets() {
6744 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6745
6746 // First, check the explicit lists.
6747 _free_list.verify_list();
6748 {
6749 // Given that a concurrent operation might be adding regions to
6750 // the secondary free list we have to take the lock before
6751 // verifying it.
6752 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6753 _secondary_free_list.verify_list();
6754 }
6755
6756 // If a concurrent region freeing operation is in progress it will
6757 // be difficult to correctly attributed any free regions we come
6758 // across to the correct free list given that they might belong to
6759 // one of several (free_list, secondary_free_list, any local lists,
6760 // etc.). So, if that's the case we will skip the rest of the
6761 // verification operation. Alternatively, waiting for the concurrent
6762 // operation to complete will have a non-trivial effect on the GC's
6763 // operation (no concurrent operation will last longer than the
6764 // interval between two calls to verification) and it might hide
6765 // any issues that we would like to catch during testing.
6766 if (free_regions_coming()) {
6767 return;
6768 }
6769
6770 // Make sure we append the secondary_free_list on the free_list so
6771 // that all free regions we will come across can be safely
6772 // attributed to the free_list.
6773 append_secondary_free_list_if_not_empty_with_lock();
6774
6775 // Finally, make sure that the region accounting in the lists is
6776 // consistent with what we see in the heap.
6777
6778 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6779 heap_region_iterate(&cl);
6780 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6781 }
6782
6783 // Optimized nmethod scanning
6784
6785 class RegisterNMethodOopClosure: public OopClosure {
6786 G1CollectedHeap* _g1h;
6787 nmethod* _nm;
6788
6789 template <class T> void do_oop_work(T* p) {
6790 T heap_oop = oopDesc::load_heap_oop(p);
6791 if (!oopDesc::is_null(heap_oop)) {
6792 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6793 HeapRegion* hr = _g1h->heap_region_containing(obj);
6794 assert(!hr->continuesHumongous(),
6795 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6796 " starting at "HR_FORMAT,
6797 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6798
6799 // HeapRegion::add_strong_code_root() avoids adding duplicate
6800 // entries but having duplicates is OK since we "mark" nmethods
6801 // as visited when we scan the strong code root lists during the GC.
6802 hr->add_strong_code_root(_nm);
6803 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6804 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6805 _nm, HR_FORMAT_PARAMS(hr)));
6806 }
6807 }
6808
6809 public:
6810 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6811 _g1h(g1h), _nm(nm) {}
6812
6813 void do_oop(oop* p) { do_oop_work(p); }
6814 void do_oop(narrowOop* p) { do_oop_work(p); }
6815 };
6816
6817 class UnregisterNMethodOopClosure: public OopClosure {
6818 G1CollectedHeap* _g1h;
6819 nmethod* _nm;
6820
6821 template <class T> void do_oop_work(T* p) {
6822 T heap_oop = oopDesc::load_heap_oop(p);
6823 if (!oopDesc::is_null(heap_oop)) {
6824 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6825 HeapRegion* hr = _g1h->heap_region_containing(obj);
6826 assert(!hr->continuesHumongous(),
6827 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6828 " starting at "HR_FORMAT,
6829 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6830
6831 hr->remove_strong_code_root(_nm);
6832 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6833 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6834 _nm, HR_FORMAT_PARAMS(hr)));
6835 }
6836 }
6837
6838 public:
6839 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6840 _g1h(g1h), _nm(nm) {}
6841
6842 void do_oop(oop* p) { do_oop_work(p); }
6843 void do_oop(narrowOop* p) { do_oop_work(p); }
6844 };
6845
6846 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6847 CollectedHeap::register_nmethod(nm);
6848
6849 guarantee(nm != NULL, "sanity");
6850 RegisterNMethodOopClosure reg_cl(this, nm);
6851 nm->oops_do(®_cl);
6852 }
6853
6854 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6855 CollectedHeap::unregister_nmethod(nm);
6856
6857 guarantee(nm != NULL, "sanity");
6858 UnregisterNMethodOopClosure reg_cl(this, nm);
6859 nm->oops_do(®_cl, true);
6860 }
6861
6862 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6863 public:
6864 bool doHeapRegion(HeapRegion *hr) {
6865 assert(!hr->isHumongous(),
6866 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6867 HR_FORMAT_PARAMS(hr)));
6868 hr->migrate_strong_code_roots();
6869 return false;
6870 }
6871 };
6872
6873 void G1CollectedHeap::migrate_strong_code_roots() {
6874 MigrateCodeRootsHeapRegionClosure cl;
6875 double migrate_start = os::elapsedTime();
6876 collection_set_iterate(&cl);
6877 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6878 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6879 }
6880
6881 void G1CollectedHeap::purge_code_root_memory() {
6882 double purge_start = os::elapsedTime();
6883 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6884 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6885 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6886 }
6887
6888 // Mark all the code roots that point into regions *not* in the
6889 // collection set.
6890 //
6891 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6892 // walking the the code roots lists of regions not in the collection
6893 // set. Suppose we have an nmethod (M) that points to objects in two
6894 // separate regions - one in the collection set (R1) and one not (R2).
6895 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6896 // nmethod M when walking the code roots for R1. When we come to scan
6897 // the code roots for R2, we would see that M is already marked and it
6898 // would be skipped and the objects in R2 that are referenced from M
6899 // would not be evacuated.
6900
6901 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6902
6903 class MarkStrongCodeRootOopClosure: public OopClosure {
6904 ConcurrentMark* _cm;
6905 HeapRegion* _hr;
6906 uint _worker_id;
6907
6908 template <class T> void do_oop_work(T* p) {
6909 T heap_oop = oopDesc::load_heap_oop(p);
6910 if (!oopDesc::is_null(heap_oop)) {
6911 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6912 // Only mark objects in the region (which is assumed
6913 // to be not in the collection set).
6914 if (_hr->is_in(obj)) {
6915 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6916 }
6917 }
6918 }
6919
6920 public:
6921 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6922 _cm(cm), _hr(hr), _worker_id(worker_id) {
6923 assert(!_hr->in_collection_set(), "sanity");
6924 }
6925
6926 void do_oop(narrowOop* p) { do_oop_work(p); }
6927 void do_oop(oop* p) { do_oop_work(p); }
6928 };
6929
6930 MarkStrongCodeRootOopClosure _oop_cl;
6931
6932 public:
6933 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6934 _oop_cl(cm, hr, worker_id) {}
6935
6936 void do_code_blob(CodeBlob* cb) {
6937 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6938 if (nm != NULL) {
6939 nm->oops_do(&_oop_cl);
6940 }
6941 }
6942 };
6943
6944 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6945 G1CollectedHeap* _g1h;
6946 uint _worker_id;
6947
6948 public:
6949 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6950 _g1h(g1h), _worker_id(worker_id) {}
6951
6952 bool doHeapRegion(HeapRegion *hr) {
6953 HeapRegionRemSet* hrrs = hr->rem_set();
6954 if (hr->continuesHumongous()) {
6955 // Code roots should never be attached to a continuation of a humongous region
6956 assert(hrrs->strong_code_roots_list_length() == 0,
6957 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6958 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6959 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6960 hrrs->strong_code_roots_list_length()));
6961 return false;
6962 }
6963
6964 if (hr->in_collection_set()) {
6965 // Don't mark code roots into regions in the collection set here.
6966 // They will be marked when we scan them.
6967 return false;
6968 }
6969
6970 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6971 hr->strong_code_roots_do(&cb_cl);
6972 return false;
6973 }
6974 };
6975
6976 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6977 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6978 if (G1CollectedHeap::use_parallel_gc_threads()) {
6979 heap_region_par_iterate_chunked(&cl,
6980 worker_id,
6981 workers()->active_workers(),
6982 HeapRegion::ParMarkRootClaimValue);
6983 } else {
6984 heap_region_iterate(&cl);
6985 }
6986 }
6987
6988 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6989 G1CollectedHeap* _g1h;
6990
6991 public:
6992 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6993 _g1h(g1h) {}
6994
6995 void do_code_blob(CodeBlob* cb) {
6996 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6997 if (nm == NULL) {
6998 return;
6999 }
7000
7001 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
7002 _g1h->register_nmethod(nm);
7003 }
7004 }
7005 };
7006
7007 void G1CollectedHeap::rebuild_strong_code_roots() {
7008 RebuildStrongCodeRootClosure blob_cl(this);
7009 CodeCache::blobs_do(&blob_cl);
7010 }