1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1StringDedup.hpp"
43 #include "gc_implementation/g1/g1YCTypes.hpp"
44 #include "gc_implementation/g1/heapRegion.inline.hpp"
45 #include "gc_implementation/g1/heapRegionRemSet.hpp"
46 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
47 #include "gc_implementation/g1/vm_operations_g1.hpp"
48 #include "gc_implementation/shared/gcHeapSummary.hpp"
49 #include "gc_implementation/shared/gcTimer.hpp"
50 #include "gc_implementation/shared/gcTrace.hpp"
51 #include "gc_implementation/shared/gcTraceTime.hpp"
52 #include "gc_implementation/shared/isGCActiveMark.hpp"
53 #include "memory/gcLocker.inline.hpp"
54 #include "memory/generationSpec.hpp"
55 #include "memory/iterator.hpp"
56 #include "memory/referenceProcessor.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/oop.pcgc.inline.hpp"
59 #include "runtime/vmThread.hpp"
60 #include "utilities/ticks.hpp"
61
62 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
63
64 // turn it on so that the contents of the young list (scan-only /
65 // to-be-collected) are printed at "strategic" points before / during
66 // / after the collection --- this is useful for debugging
67 #define YOUNG_LIST_VERBOSE 0
68 // CURRENT STATUS
69 // This file is under construction. Search for "FIXME".
70
71 // INVARIANTS/NOTES
72 //
73 // All allocation activity covered by the G1CollectedHeap interface is
74 // serialized by acquiring the HeapLock. This happens in mem_allocate
75 // and allocate_new_tlab, which are the "entry" points to the
76 // allocation code from the rest of the JVM. (Note that this does not
77 // apply to TLAB allocation, which is not part of this interface: it
78 // is done by clients of this interface.)
79
80 // Notes on implementation of parallelism in different tasks.
81 //
82 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
83 // The number of GC workers is passed to heap_region_par_iterate_chunked().
84 // It does use run_task() which sets _n_workers in the task.
85 // G1ParTask executes g1_process_strong_roots() ->
86 // SharedHeap::process_strong_roots() which calls eventually to
87 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
88 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
89 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
90 //
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
119 size_t _num_processed;
120 CardTableModRefBS* _ctbs;
121 int _histo[256];
122
123 public:
124 ClearLoggedCardTableEntryClosure() :
125 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
126 {
127 for (int i = 0; i < 256; i++) _histo[i] = 0;
128 }
129
130 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
131 unsigned char* ujb = (unsigned char*)card_ptr;
132 int ind = (int)(*ujb);
133 _histo[ind]++;
134
135 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
136 _num_processed++;
137
138 return true;
139 }
140
141 size_t num_processed() { return _num_processed; }
142
143 void print_histo() {
144 gclog_or_tty->print_cr("Card table value histogram:");
145 for (int i = 0; i < 256; i++) {
146 if (_histo[i] != 0) {
147 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
148 }
149 }
150 }
151 };
152
153 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
154 private:
155 size_t _num_processed;
156
157 public:
158 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
159
160 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
161 *card_ptr = CardTableModRefBS::dirty_card_val();
162 _num_processed++;
163 return true;
164 }
165
166 size_t num_processed() const { return _num_processed; }
167 };
168
169 YoungList::YoungList(G1CollectedHeap* g1h) :
170 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
171 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
172 guarantee(check_list_empty(false), "just making sure...");
173 }
174
175 void YoungList::push_region(HeapRegion *hr) {
176 assert(!hr->is_young(), "should not already be young");
177 assert(hr->get_next_young_region() == NULL, "cause it should!");
178
179 hr->set_next_young_region(_head);
180 _head = hr;
181
182 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
183 ++_length;
184 }
185
186 void YoungList::add_survivor_region(HeapRegion* hr) {
187 assert(hr->is_survivor(), "should be flagged as survivor region");
188 assert(hr->get_next_young_region() == NULL, "cause it should!");
189
190 hr->set_next_young_region(_survivor_head);
191 if (_survivor_head == NULL) {
192 _survivor_tail = hr;
193 }
194 _survivor_head = hr;
195 ++_survivor_length;
196 }
197
198 void YoungList::empty_list(HeapRegion* list) {
199 while (list != NULL) {
200 HeapRegion* next = list->get_next_young_region();
201 list->set_next_young_region(NULL);
202 list->uninstall_surv_rate_group();
203 list->set_not_young();
204 list = next;
205 }
206 }
207
208 void YoungList::empty_list() {
209 assert(check_list_well_formed(), "young list should be well formed");
210
211 empty_list(_head);
212 _head = NULL;
213 _length = 0;
214
215 empty_list(_survivor_head);
216 _survivor_head = NULL;
217 _survivor_tail = NULL;
218 _survivor_length = 0;
219
220 _last_sampled_rs_lengths = 0;
221
222 assert(check_list_empty(false), "just making sure...");
223 }
224
225 bool YoungList::check_list_well_formed() {
226 bool ret = true;
227
228 uint length = 0;
229 HeapRegion* curr = _head;
230 HeapRegion* last = NULL;
231 while (curr != NULL) {
232 if (!curr->is_young()) {
233 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
234 "incorrectly tagged (y: %d, surv: %d)",
235 curr->bottom(), curr->end(),
236 curr->is_young(), curr->is_survivor());
237 ret = false;
238 }
239 ++length;
240 last = curr;
241 curr = curr->get_next_young_region();
242 }
243 ret = ret && (length == _length);
244
245 if (!ret) {
246 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
247 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
248 length, _length);
249 }
250
251 return ret;
252 }
253
254 bool YoungList::check_list_empty(bool check_sample) {
255 bool ret = true;
256
257 if (_length != 0) {
258 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
259 _length);
260 ret = false;
261 }
262 if (check_sample && _last_sampled_rs_lengths != 0) {
263 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
264 ret = false;
265 }
266 if (_head != NULL) {
267 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
268 ret = false;
269 }
270 if (!ret) {
271 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
272 }
273
274 return ret;
275 }
276
277 void
278 YoungList::rs_length_sampling_init() {
279 _sampled_rs_lengths = 0;
280 _curr = _head;
281 }
282
283 bool
284 YoungList::rs_length_sampling_more() {
285 return _curr != NULL;
286 }
287
288 void
289 YoungList::rs_length_sampling_next() {
290 assert( _curr != NULL, "invariant" );
291 size_t rs_length = _curr->rem_set()->occupied();
292
293 _sampled_rs_lengths += rs_length;
294
295 // The current region may not yet have been added to the
296 // incremental collection set (it gets added when it is
297 // retired as the current allocation region).
298 if (_curr->in_collection_set()) {
299 // Update the collection set policy information for this region
300 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
301 }
302
303 _curr = _curr->get_next_young_region();
304 if (_curr == NULL) {
305 _last_sampled_rs_lengths = _sampled_rs_lengths;
306 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
307 }
308 }
309
310 void
311 YoungList::reset_auxilary_lists() {
312 guarantee( is_empty(), "young list should be empty" );
313 assert(check_list_well_formed(), "young list should be well formed");
314
315 // Add survivor regions to SurvRateGroup.
316 _g1h->g1_policy()->note_start_adding_survivor_regions();
317 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
318
319 int young_index_in_cset = 0;
320 for (HeapRegion* curr = _survivor_head;
321 curr != NULL;
322 curr = curr->get_next_young_region()) {
323 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
324
325 // The region is a non-empty survivor so let's add it to
326 // the incremental collection set for the next evacuation
327 // pause.
328 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
329 young_index_in_cset += 1;
330 }
331 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
332 _g1h->g1_policy()->note_stop_adding_survivor_regions();
333
334 _head = _survivor_head;
335 _length = _survivor_length;
336 if (_survivor_head != NULL) {
337 assert(_survivor_tail != NULL, "cause it shouldn't be");
338 assert(_survivor_length > 0, "invariant");
339 _survivor_tail->set_next_young_region(NULL);
340 }
341
342 // Don't clear the survivor list handles until the start of
343 // the next evacuation pause - we need it in order to re-tag
344 // the survivor regions from this evacuation pause as 'young'
345 // at the start of the next.
346
347 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
348
349 assert(check_list_well_formed(), "young list should be well formed");
350 }
351
352 void YoungList::print() {
353 HeapRegion* lists[] = {_head, _survivor_head};
354 const char* names[] = {"YOUNG", "SURVIVOR"};
355
356 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
357 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
358 HeapRegion *curr = lists[list];
359 if (curr == NULL)
360 gclog_or_tty->print_cr(" empty");
361 while (curr != NULL) {
362 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
363 HR_FORMAT_PARAMS(curr),
364 curr->prev_top_at_mark_start(),
365 curr->next_top_at_mark_start(),
366 curr->age_in_surv_rate_group_cond());
367 curr = curr->get_next_young_region();
368 }
369 }
370
371 gclog_or_tty->print_cr("");
372 }
373
374 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
375 {
376 // Claim the right to put the region on the dirty cards region list
377 // by installing a self pointer.
378 HeapRegion* next = hr->get_next_dirty_cards_region();
379 if (next == NULL) {
380 HeapRegion* res = (HeapRegion*)
381 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
382 NULL);
383 if (res == NULL) {
384 HeapRegion* head;
385 do {
386 // Put the region to the dirty cards region list.
387 head = _dirty_cards_region_list;
388 next = (HeapRegion*)
389 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
390 if (next == head) {
391 assert(hr->get_next_dirty_cards_region() == hr,
392 "hr->get_next_dirty_cards_region() != hr");
393 if (next == NULL) {
394 // The last region in the list points to itself.
395 hr->set_next_dirty_cards_region(hr);
396 } else {
397 hr->set_next_dirty_cards_region(next);
398 }
399 }
400 } while (next != head);
401 }
402 }
403 }
404
405 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
406 {
407 HeapRegion* head;
408 HeapRegion* hr;
409 do {
410 head = _dirty_cards_region_list;
411 if (head == NULL) {
412 return NULL;
413 }
414 HeapRegion* new_head = head->get_next_dirty_cards_region();
415 if (head == new_head) {
416 // The last region.
417 new_head = NULL;
418 }
419 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
420 head);
421 } while (hr != head);
422 assert(hr != NULL, "invariant");
423 hr->set_next_dirty_cards_region(NULL);
424 return hr;
425 }
426
427 void G1CollectedHeap::stop_conc_gc_threads() {
428 _cg1r->stop();
429 _cmThread->stop();
430 if (G1StringDedup::is_enabled()) {
431 G1StringDedup::stop();
432 }
433 }
434
435 #ifdef ASSERT
436 // A region is added to the collection set as it is retired
437 // so an address p can point to a region which will be in the
438 // collection set but has not yet been retired. This method
439 // therefore is only accurate during a GC pause after all
440 // regions have been retired. It is used for debugging
441 // to check if an nmethod has references to objects that can
442 // be move during a partial collection. Though it can be
443 // inaccurate, it is sufficient for G1 because the conservative
444 // implementation of is_scavengable() for G1 will indicate that
445 // all nmethods must be scanned during a partial collection.
446 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
447 HeapRegion* hr = heap_region_containing(p);
448 return hr != NULL && hr->in_collection_set();
449 }
450 #endif
451
452 // Returns true if the reference points to an object that
453 // can move in an incremental collection.
454 bool G1CollectedHeap::is_scavengable(const void* p) {
455 G1CollectedHeap* g1h = G1CollectedHeap::heap();
456 G1CollectorPolicy* g1p = g1h->g1_policy();
457 HeapRegion* hr = heap_region_containing(p);
458 if (hr == NULL) {
459 // null
460 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
461 return false;
462 } else {
463 return !hr->isHumongous();
464 }
465 }
466
467 void G1CollectedHeap::check_ct_logs_at_safepoint() {
468 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
469 CardTableModRefBS* ct_bs = g1_barrier_set();
470
471 // Count the dirty cards at the start.
472 CountNonCleanMemRegionClosure count1(this);
473 ct_bs->mod_card_iterate(&count1);
474 int orig_count = count1.n();
475
476 // First clear the logged cards.
477 ClearLoggedCardTableEntryClosure clear;
478 dcqs.apply_closure_to_all_completed_buffers(&clear);
479 dcqs.iterate_closure_all_threads(&clear, false);
480 clear.print_histo();
481
482 // Now ensure that there's no dirty cards.
483 CountNonCleanMemRegionClosure count2(this);
484 ct_bs->mod_card_iterate(&count2);
485 if (count2.n() != 0) {
486 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
487 count2.n(), orig_count);
488 }
489 guarantee(count2.n() == 0, "Card table should be clean.");
490
491 RedirtyLoggedCardTableEntryClosure redirty;
492 dcqs.apply_closure_to_all_completed_buffers(&redirty);
493 dcqs.iterate_closure_all_threads(&redirty, false);
494 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
495 clear.num_processed(), orig_count);
496 guarantee(redirty.num_processed() == clear.num_processed(),
497 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
498 redirty.num_processed(), clear.num_processed()));
499
500 CountNonCleanMemRegionClosure count3(this);
501 ct_bs->mod_card_iterate(&count3);
502 if (count3.n() != orig_count) {
503 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
504 orig_count, count3.n());
505 guarantee(count3.n() >= orig_count, "Should have restored them all.");
506 }
507 }
508
509 // Private class members.
510
511 G1CollectedHeap* G1CollectedHeap::_g1h;
512
513 // Private methods.
514
515 HeapRegion*
516 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
517 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
518 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
519 if (!_secondary_free_list.is_empty()) {
520 if (G1ConcRegionFreeingVerbose) {
521 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
522 "secondary_free_list has %u entries",
523 _secondary_free_list.length());
524 }
525 // It looks as if there are free regions available on the
526 // secondary_free_list. Let's move them to the free_list and try
527 // again to allocate from it.
528 append_secondary_free_list();
529
530 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
531 "empty we should have moved at least one entry to the free_list");
532 HeapRegion* res = _free_list.remove_region(is_old);
533 if (G1ConcRegionFreeingVerbose) {
534 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
535 "allocated "HR_FORMAT" from secondary_free_list",
536 HR_FORMAT_PARAMS(res));
537 }
538 return res;
539 }
540
541 // Wait here until we get notified either when (a) there are no
542 // more free regions coming or (b) some regions have been moved on
543 // the secondary_free_list.
544 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
545 }
546
547 if (G1ConcRegionFreeingVerbose) {
548 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
549 "could not allocate from secondary_free_list");
550 }
551 return NULL;
552 }
553
554 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
555 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
556 "the only time we use this to allocate a humongous region is "
557 "when we are allocating a single humongous region");
558
559 HeapRegion* res;
560 if (G1StressConcRegionFreeing) {
561 if (!_secondary_free_list.is_empty()) {
562 if (G1ConcRegionFreeingVerbose) {
563 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
564 "forced to look at the secondary_free_list");
565 }
566 res = new_region_try_secondary_free_list(is_old);
567 if (res != NULL) {
568 return res;
569 }
570 }
571 }
572
573 res = _free_list.remove_region(is_old);
574
575 if (res == NULL) {
576 if (G1ConcRegionFreeingVerbose) {
577 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
578 "res == NULL, trying the secondary_free_list");
579 }
580 res = new_region_try_secondary_free_list(is_old);
581 }
582 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
583 // Currently, only attempts to allocate GC alloc regions set
584 // do_expand to true. So, we should only reach here during a
585 // safepoint. If this assumption changes we might have to
586 // reconsider the use of _expand_heap_after_alloc_failure.
587 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
588
589 ergo_verbose1(ErgoHeapSizing,
590 "attempt heap expansion",
591 ergo_format_reason("region allocation request failed")
592 ergo_format_byte("allocation request"),
593 word_size * HeapWordSize);
594 if (expand(word_size * HeapWordSize)) {
595 // Given that expand() succeeded in expanding the heap, and we
596 // always expand the heap by an amount aligned to the heap
597 // region size, the free list should in theory not be empty.
598 // In either case remove_region() will check for NULL.
599 res = _free_list.remove_region(is_old);
600 } else {
601 _expand_heap_after_alloc_failure = false;
602 }
603 }
604 return res;
605 }
606
607 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
608 size_t word_size) {
609 assert(isHumongous(word_size), "word_size should be humongous");
610 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
611
612 uint first = G1_NULL_HRS_INDEX;
613 if (num_regions == 1) {
614 // Only one region to allocate, no need to go through the slower
615 // path. The caller will attempt the expansion if this fails, so
616 // let's not try to expand here too.
617 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
618 if (hr != NULL) {
619 first = hr->hrs_index();
620 } else {
621 first = G1_NULL_HRS_INDEX;
622 }
623 } else {
624 // We can't allocate humongous regions while cleanupComplete() is
625 // running, since some of the regions we find to be empty might not
626 // yet be added to the free list and it is not straightforward to
627 // know which list they are on so that we can remove them. Note
628 // that we only need to do this if we need to allocate more than
629 // one region to satisfy the current humongous allocation
630 // request. If we are only allocating one region we use the common
631 // region allocation code (see above).
632 wait_while_free_regions_coming();
633 append_secondary_free_list_if_not_empty_with_lock();
634
635 if (free_regions() >= num_regions) {
636 first = _hrs.find_contiguous(num_regions);
637 if (first != G1_NULL_HRS_INDEX) {
638 for (uint i = first; i < first + num_regions; ++i) {
639 HeapRegion* hr = region_at(i);
640 assert(hr->is_empty(), "sanity");
641 assert(is_on_master_free_list(hr), "sanity");
642 hr->set_pending_removal(true);
643 }
644 _free_list.remove_all_pending(num_regions);
645 }
646 }
647 }
648 return first;
649 }
650
651 HeapWord*
652 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
653 uint num_regions,
654 size_t word_size) {
655 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
656 assert(isHumongous(word_size), "word_size should be humongous");
657 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
658
659 // Index of last region in the series + 1.
660 uint last = first + num_regions;
661
662 // We need to initialize the region(s) we just discovered. This is
663 // a bit tricky given that it can happen concurrently with
664 // refinement threads refining cards on these regions and
665 // potentially wanting to refine the BOT as they are scanning
666 // those cards (this can happen shortly after a cleanup; see CR
667 // 6991377). So we have to set up the region(s) carefully and in
668 // a specific order.
669
670 // The word size sum of all the regions we will allocate.
671 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
672 assert(word_size <= word_size_sum, "sanity");
673
674 // This will be the "starts humongous" region.
675 HeapRegion* first_hr = region_at(first);
676 // The header of the new object will be placed at the bottom of
677 // the first region.
678 HeapWord* new_obj = first_hr->bottom();
679 // This will be the new end of the first region in the series that
680 // should also match the end of the last region in the series.
681 HeapWord* new_end = new_obj + word_size_sum;
682 // This will be the new top of the first region that will reflect
683 // this allocation.
684 HeapWord* new_top = new_obj + word_size;
685
686 // First, we need to zero the header of the space that we will be
687 // allocating. When we update top further down, some refinement
688 // threads might try to scan the region. By zeroing the header we
689 // ensure that any thread that will try to scan the region will
690 // come across the zero klass word and bail out.
691 //
692 // NOTE: It would not have been correct to have used
693 // CollectedHeap::fill_with_object() and make the space look like
694 // an int array. The thread that is doing the allocation will
695 // later update the object header to a potentially different array
696 // type and, for a very short period of time, the klass and length
697 // fields will be inconsistent. This could cause a refinement
698 // thread to calculate the object size incorrectly.
699 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
700
701 // We will set up the first region as "starts humongous". This
702 // will also update the BOT covering all the regions to reflect
703 // that there is a single object that starts at the bottom of the
704 // first region.
705 first_hr->set_startsHumongous(new_top, new_end);
706
707 // Then, if there are any, we will set up the "continues
708 // humongous" regions.
709 HeapRegion* hr = NULL;
710 for (uint i = first + 1; i < last; ++i) {
711 hr = region_at(i);
712 hr->set_continuesHumongous(first_hr);
713 }
714 // If we have "continues humongous" regions (hr != NULL), then the
715 // end of the last one should match new_end.
716 assert(hr == NULL || hr->end() == new_end, "sanity");
717
718 // Up to this point no concurrent thread would have been able to
719 // do any scanning on any region in this series. All the top
720 // fields still point to bottom, so the intersection between
721 // [bottom,top] and [card_start,card_end] will be empty. Before we
722 // update the top fields, we'll do a storestore to make sure that
723 // no thread sees the update to top before the zeroing of the
724 // object header and the BOT initialization.
725 OrderAccess::storestore();
726
727 // Now that the BOT and the object header have been initialized,
728 // we can update top of the "starts humongous" region.
729 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
730 "new_top should be in this region");
731 first_hr->set_top(new_top);
732 if (_hr_printer.is_active()) {
733 HeapWord* bottom = first_hr->bottom();
734 HeapWord* end = first_hr->orig_end();
735 if ((first + 1) == last) {
736 // the series has a single humongous region
737 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
738 } else {
739 // the series has more than one humongous regions
740 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
741 }
742 }
743
744 // Now, we will update the top fields of the "continues humongous"
745 // regions. The reason we need to do this is that, otherwise,
746 // these regions would look empty and this will confuse parts of
747 // G1. For example, the code that looks for a consecutive number
748 // of empty regions will consider them empty and try to
749 // re-allocate them. We can extend is_empty() to also include
750 // !continuesHumongous(), but it is easier to just update the top
751 // fields here. The way we set top for all regions (i.e., top ==
752 // end for all regions but the last one, top == new_top for the
753 // last one) is actually used when we will free up the humongous
754 // region in free_humongous_region().
755 hr = NULL;
756 for (uint i = first + 1; i < last; ++i) {
757 hr = region_at(i);
758 if ((i + 1) == last) {
759 // last continues humongous region
760 assert(hr->bottom() < new_top && new_top <= hr->end(),
761 "new_top should fall on this region");
762 hr->set_top(new_top);
763 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
764 } else {
765 // not last one
766 assert(new_top > hr->end(), "new_top should be above this region");
767 hr->set_top(hr->end());
768 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
769 }
770 }
771 // If we have continues humongous regions (hr != NULL), then the
772 // end of the last one should match new_end and its top should
773 // match new_top.
774 assert(hr == NULL ||
775 (hr->end() == new_end && hr->top() == new_top), "sanity");
776
777 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
778 _summary_bytes_used += first_hr->used();
779 _humongous_set.add(first_hr);
780
781 return new_obj;
782 }
783
784 // If could fit into free regions w/o expansion, try.
785 // Otherwise, if can expand, do so.
786 // Otherwise, if using ex regions might help, try with ex given back.
787 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
788 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
789
790 verify_region_sets_optional();
791
792 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
793 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
794 uint x_num = expansion_regions();
795 uint fs = _hrs.free_suffix();
796 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
797 if (first == G1_NULL_HRS_INDEX) {
798 // The only thing we can do now is attempt expansion.
799 if (fs + x_num >= num_regions) {
800 // If the number of regions we're trying to allocate for this
801 // object is at most the number of regions in the free suffix,
802 // then the call to humongous_obj_allocate_find_first() above
803 // should have succeeded and we wouldn't be here.
804 //
805 // We should only be trying to expand when the free suffix is
806 // not sufficient for the object _and_ we have some expansion
807 // room available.
808 assert(num_regions > fs, "earlier allocation should have succeeded");
809
810 ergo_verbose1(ErgoHeapSizing,
811 "attempt heap expansion",
812 ergo_format_reason("humongous allocation request failed")
813 ergo_format_byte("allocation request"),
814 word_size * HeapWordSize);
815 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
816 // Even though the heap was expanded, it might not have
817 // reached the desired size. So, we cannot assume that the
818 // allocation will succeed.
819 first = humongous_obj_allocate_find_first(num_regions, word_size);
820 }
821 }
822 }
823
824 HeapWord* result = NULL;
825 if (first != G1_NULL_HRS_INDEX) {
826 result =
827 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
828 assert(result != NULL, "it should always return a valid result");
829
830 // A successful humongous object allocation changes the used space
831 // information of the old generation so we need to recalculate the
832 // sizes and update the jstat counters here.
833 g1mm()->update_sizes();
834 }
835
836 verify_region_sets_optional();
837
838 return result;
839 }
840
841 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
842 assert_heap_not_locked_and_not_at_safepoint();
843 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
844
845 unsigned int dummy_gc_count_before;
846 int dummy_gclocker_retry_count = 0;
847 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
848 }
849
850 HeapWord*
851 G1CollectedHeap::mem_allocate(size_t word_size,
852 bool* gc_overhead_limit_was_exceeded) {
853 assert_heap_not_locked_and_not_at_safepoint();
854
855 // Loop until the allocation is satisfied, or unsatisfied after GC.
856 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
857 unsigned int gc_count_before;
858
859 HeapWord* result = NULL;
860 if (!isHumongous(word_size)) {
861 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
862 } else {
863 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
864 }
865 if (result != NULL) {
866 return result;
867 }
868
869 // Create the garbage collection operation...
870 VM_G1CollectForAllocation op(gc_count_before, word_size);
871 // ...and get the VM thread to execute it.
872 VMThread::execute(&op);
873
874 if (op.prologue_succeeded() && op.pause_succeeded()) {
875 // If the operation was successful we'll return the result even
876 // if it is NULL. If the allocation attempt failed immediately
877 // after a Full GC, it's unlikely we'll be able to allocate now.
878 HeapWord* result = op.result();
879 if (result != NULL && !isHumongous(word_size)) {
880 // Allocations that take place on VM operations do not do any
881 // card dirtying and we have to do it here. We only have to do
882 // this for non-humongous allocations, though.
883 dirty_young_block(result, word_size);
884 }
885 return result;
886 } else {
887 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
888 return NULL;
889 }
890 assert(op.result() == NULL,
891 "the result should be NULL if the VM op did not succeed");
892 }
893
894 // Give a warning if we seem to be looping forever.
895 if ((QueuedAllocationWarningCount > 0) &&
896 (try_count % QueuedAllocationWarningCount == 0)) {
897 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
898 }
899 }
900
901 ShouldNotReachHere();
902 return NULL;
903 }
904
905 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
906 unsigned int *gc_count_before_ret,
907 int* gclocker_retry_count_ret) {
908 // Make sure you read the note in attempt_allocation_humongous().
909
910 assert_heap_not_locked_and_not_at_safepoint();
911 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
912 "be called for humongous allocation requests");
913
914 // We should only get here after the first-level allocation attempt
915 // (attempt_allocation()) failed to allocate.
916
917 // We will loop until a) we manage to successfully perform the
918 // allocation or b) we successfully schedule a collection which
919 // fails to perform the allocation. b) is the only case when we'll
920 // return NULL.
921 HeapWord* result = NULL;
922 for (int try_count = 1; /* we'll return */; try_count += 1) {
923 bool should_try_gc;
924 unsigned int gc_count_before;
925
926 {
927 MutexLockerEx x(Heap_lock);
928
929 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
930 false /* bot_updates */);
931 if (result != NULL) {
932 return result;
933 }
934
935 // If we reach here, attempt_allocation_locked() above failed to
936 // allocate a new region. So the mutator alloc region should be NULL.
937 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
938
939 if (GC_locker::is_active_and_needs_gc()) {
940 if (g1_policy()->can_expand_young_list()) {
941 // No need for an ergo verbose message here,
942 // can_expand_young_list() does this when it returns true.
943 result = _mutator_alloc_region.attempt_allocation_force(word_size,
944 false /* bot_updates */);
945 if (result != NULL) {
946 return result;
947 }
948 }
949 should_try_gc = false;
950 } else {
951 // The GCLocker may not be active but the GCLocker initiated
952 // GC may not yet have been performed (GCLocker::needs_gc()
953 // returns true). In this case we do not try this GC and
954 // wait until the GCLocker initiated GC is performed, and
955 // then retry the allocation.
956 if (GC_locker::needs_gc()) {
957 should_try_gc = false;
958 } else {
959 // Read the GC count while still holding the Heap_lock.
960 gc_count_before = total_collections();
961 should_try_gc = true;
962 }
963 }
964 }
965
966 if (should_try_gc) {
967 bool succeeded;
968 result = do_collection_pause(word_size, gc_count_before, &succeeded,
969 GCCause::_g1_inc_collection_pause);
970 if (result != NULL) {
971 assert(succeeded, "only way to get back a non-NULL result");
972 return result;
973 }
974
975 if (succeeded) {
976 // If we get here we successfully scheduled a collection which
977 // failed to allocate. No point in trying to allocate
978 // further. We'll just return NULL.
979 MutexLockerEx x(Heap_lock);
980 *gc_count_before_ret = total_collections();
981 return NULL;
982 }
983 } else {
984 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
985 MutexLockerEx x(Heap_lock);
986 *gc_count_before_ret = total_collections();
987 return NULL;
988 }
989 // The GCLocker is either active or the GCLocker initiated
990 // GC has not yet been performed. Stall until it is and
991 // then retry the allocation.
992 GC_locker::stall_until_clear();
993 (*gclocker_retry_count_ret) += 1;
994 }
995
996 // We can reach here if we were unsuccessful in scheduling a
997 // collection (because another thread beat us to it) or if we were
998 // stalled due to the GC locker. In either can we should retry the
999 // allocation attempt in case another thread successfully
1000 // performed a collection and reclaimed enough space. We do the
1001 // first attempt (without holding the Heap_lock) here and the
1002 // follow-on attempt will be at the start of the next loop
1003 // iteration (after taking the Heap_lock).
1004 result = _mutator_alloc_region.attempt_allocation(word_size,
1005 false /* bot_updates */);
1006 if (result != NULL) {
1007 return result;
1008 }
1009
1010 // Give a warning if we seem to be looping forever.
1011 if ((QueuedAllocationWarningCount > 0) &&
1012 (try_count % QueuedAllocationWarningCount == 0)) {
1013 warning("G1CollectedHeap::attempt_allocation_slow() "
1014 "retries %d times", try_count);
1015 }
1016 }
1017
1018 ShouldNotReachHere();
1019 return NULL;
1020 }
1021
1022 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1023 unsigned int * gc_count_before_ret,
1024 int* gclocker_retry_count_ret) {
1025 // The structure of this method has a lot of similarities to
1026 // attempt_allocation_slow(). The reason these two were not merged
1027 // into a single one is that such a method would require several "if
1028 // allocation is not humongous do this, otherwise do that"
1029 // conditional paths which would obscure its flow. In fact, an early
1030 // version of this code did use a unified method which was harder to
1031 // follow and, as a result, it had subtle bugs that were hard to
1032 // track down. So keeping these two methods separate allows each to
1033 // be more readable. It will be good to keep these two in sync as
1034 // much as possible.
1035
1036 assert_heap_not_locked_and_not_at_safepoint();
1037 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1038 "should only be called for humongous allocations");
1039
1040 // Humongous objects can exhaust the heap quickly, so we should check if we
1041 // need to start a marking cycle at each humongous object allocation. We do
1042 // the check before we do the actual allocation. The reason for doing it
1043 // before the allocation is that we avoid having to keep track of the newly
1044 // allocated memory while we do a GC.
1045 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1046 word_size)) {
1047 collect(GCCause::_g1_humongous_allocation);
1048 }
1049
1050 // We will loop until a) we manage to successfully perform the
1051 // allocation or b) we successfully schedule a collection which
1052 // fails to perform the allocation. b) is the only case when we'll
1053 // return NULL.
1054 HeapWord* result = NULL;
1055 for (int try_count = 1; /* we'll return */; try_count += 1) {
1056 bool should_try_gc;
1057 unsigned int gc_count_before;
1058
1059 {
1060 MutexLockerEx x(Heap_lock);
1061
1062 // Given that humongous objects are not allocated in young
1063 // regions, we'll first try to do the allocation without doing a
1064 // collection hoping that there's enough space in the heap.
1065 result = humongous_obj_allocate(word_size);
1066 if (result != NULL) {
1067 return result;
1068 }
1069
1070 if (GC_locker::is_active_and_needs_gc()) {
1071 should_try_gc = false;
1072 } else {
1073 // The GCLocker may not be active but the GCLocker initiated
1074 // GC may not yet have been performed (GCLocker::needs_gc()
1075 // returns true). In this case we do not try this GC and
1076 // wait until the GCLocker initiated GC is performed, and
1077 // then retry the allocation.
1078 if (GC_locker::needs_gc()) {
1079 should_try_gc = false;
1080 } else {
1081 // Read the GC count while still holding the Heap_lock.
1082 gc_count_before = total_collections();
1083 should_try_gc = true;
1084 }
1085 }
1086 }
1087
1088 if (should_try_gc) {
1089 // If we failed to allocate the humongous object, we should try to
1090 // do a collection pause (if we're allowed) in case it reclaims
1091 // enough space for the allocation to succeed after the pause.
1092
1093 bool succeeded;
1094 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1095 GCCause::_g1_humongous_allocation);
1096 if (result != NULL) {
1097 assert(succeeded, "only way to get back a non-NULL result");
1098 return result;
1099 }
1100
1101 if (succeeded) {
1102 // If we get here we successfully scheduled a collection which
1103 // failed to allocate. No point in trying to allocate
1104 // further. We'll just return NULL.
1105 MutexLockerEx x(Heap_lock);
1106 *gc_count_before_ret = total_collections();
1107 return NULL;
1108 }
1109 } else {
1110 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1111 MutexLockerEx x(Heap_lock);
1112 *gc_count_before_ret = total_collections();
1113 return NULL;
1114 }
1115 // The GCLocker is either active or the GCLocker initiated
1116 // GC has not yet been performed. Stall until it is and
1117 // then retry the allocation.
1118 GC_locker::stall_until_clear();
1119 (*gclocker_retry_count_ret) += 1;
1120 }
1121
1122 // We can reach here if we were unsuccessful in scheduling a
1123 // collection (because another thread beat us to it) or if we were
1124 // stalled due to the GC locker. In either can we should retry the
1125 // allocation attempt in case another thread successfully
1126 // performed a collection and reclaimed enough space. Give a
1127 // warning if we seem to be looping forever.
1128
1129 if ((QueuedAllocationWarningCount > 0) &&
1130 (try_count % QueuedAllocationWarningCount == 0)) {
1131 warning("G1CollectedHeap::attempt_allocation_humongous() "
1132 "retries %d times", try_count);
1133 }
1134 }
1135
1136 ShouldNotReachHere();
1137 return NULL;
1138 }
1139
1140 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1141 bool expect_null_mutator_alloc_region) {
1142 assert_at_safepoint(true /* should_be_vm_thread */);
1143 assert(_mutator_alloc_region.get() == NULL ||
1144 !expect_null_mutator_alloc_region,
1145 "the current alloc region was unexpectedly found to be non-NULL");
1146
1147 if (!isHumongous(word_size)) {
1148 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1149 false /* bot_updates */);
1150 } else {
1151 HeapWord* result = humongous_obj_allocate(word_size);
1152 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1153 g1_policy()->set_initiate_conc_mark_if_possible();
1154 }
1155 return result;
1156 }
1157
1158 ShouldNotReachHere();
1159 }
1160
1161 class PostMCRemSetClearClosure: public HeapRegionClosure {
1162 G1CollectedHeap* _g1h;
1163 ModRefBarrierSet* _mr_bs;
1164 public:
1165 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1166 _g1h(g1h), _mr_bs(mr_bs) {}
1167
1168 bool doHeapRegion(HeapRegion* r) {
1169 HeapRegionRemSet* hrrs = r->rem_set();
1170
1171 if (r->continuesHumongous()) {
1172 // We'll assert that the strong code root list and RSet is empty
1173 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1174 assert(hrrs->occupied() == 0, "RSet should be empty");
1175 return false;
1176 }
1177
1178 _g1h->reset_gc_time_stamps(r);
1179 hrrs->clear();
1180 // You might think here that we could clear just the cards
1181 // corresponding to the used region. But no: if we leave a dirty card
1182 // in a region we might allocate into, then it would prevent that card
1183 // from being enqueued, and cause it to be missed.
1184 // Re: the performance cost: we shouldn't be doing full GC anyway!
1185 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1186
1187 return false;
1188 }
1189 };
1190
1191 void G1CollectedHeap::clear_rsets_post_compaction() {
1192 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1193 heap_region_iterate(&rs_clear);
1194 }
1195
1196 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1197 G1CollectedHeap* _g1h;
1198 UpdateRSOopClosure _cl;
1199 int _worker_i;
1200 public:
1201 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1202 _cl(g1->g1_rem_set(), worker_i),
1203 _worker_i(worker_i),
1204 _g1h(g1)
1205 { }
1206
1207 bool doHeapRegion(HeapRegion* r) {
1208 if (!r->continuesHumongous()) {
1209 _cl.set_from(r);
1210 r->oop_iterate(&_cl);
1211 }
1212 return false;
1213 }
1214 };
1215
1216 class ParRebuildRSTask: public AbstractGangTask {
1217 G1CollectedHeap* _g1;
1218 public:
1219 ParRebuildRSTask(G1CollectedHeap* g1)
1220 : AbstractGangTask("ParRebuildRSTask"),
1221 _g1(g1)
1222 { }
1223
1224 void work(uint worker_id) {
1225 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1226 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1227 _g1->workers()->active_workers(),
1228 HeapRegion::RebuildRSClaimValue);
1229 }
1230 };
1231
1232 class PostCompactionPrinterClosure: public HeapRegionClosure {
1233 private:
1234 G1HRPrinter* _hr_printer;
1235 public:
1236 bool doHeapRegion(HeapRegion* hr) {
1237 assert(!hr->is_young(), "not expecting to find young regions");
1238 // We only generate output for non-empty regions.
1239 if (!hr->is_empty()) {
1240 if (!hr->isHumongous()) {
1241 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1242 } else if (hr->startsHumongous()) {
1243 if (hr->region_num() == 1) {
1244 // single humongous region
1245 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1246 } else {
1247 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1248 }
1249 } else {
1250 assert(hr->continuesHumongous(), "only way to get here");
1251 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1252 }
1253 }
1254 return false;
1255 }
1256
1257 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1258 : _hr_printer(hr_printer) { }
1259 };
1260
1261 void G1CollectedHeap::print_hrs_post_compaction() {
1262 PostCompactionPrinterClosure cl(hr_printer());
1263 heap_region_iterate(&cl);
1264 }
1265
1266 bool G1CollectedHeap::do_collection(bool explicit_gc,
1267 bool clear_all_soft_refs,
1268 size_t word_size) {
1269 assert_at_safepoint(true /* should_be_vm_thread */);
1270
1271 if (GC_locker::check_active_before_gc()) {
1272 return false;
1273 }
1274
1275 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1276 gc_timer->register_gc_start();
1277
1278 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1279 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1280
1281 SvcGCMarker sgcm(SvcGCMarker::FULL);
1282 ResourceMark rm;
1283
1284 print_heap_before_gc();
1285 trace_heap_before_gc(gc_tracer);
1286
1287 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1288
1289 verify_region_sets_optional();
1290
1291 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1292 collector_policy()->should_clear_all_soft_refs();
1293
1294 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1295
1296 {
1297 IsGCActiveMark x;
1298
1299 // Timing
1300 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1301 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1302 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1303
1304 {
1305 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1306 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1307 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1308
1309 double start = os::elapsedTime();
1310 g1_policy()->record_full_collection_start();
1311
1312 // Note: When we have a more flexible GC logging framework that
1313 // allows us to add optional attributes to a GC log record we
1314 // could consider timing and reporting how long we wait in the
1315 // following two methods.
1316 wait_while_free_regions_coming();
1317 // If we start the compaction before the CM threads finish
1318 // scanning the root regions we might trip them over as we'll
1319 // be moving objects / updating references. So let's wait until
1320 // they are done. By telling them to abort, they should complete
1321 // early.
1322 _cm->root_regions()->abort();
1323 _cm->root_regions()->wait_until_scan_finished();
1324 append_secondary_free_list_if_not_empty_with_lock();
1325
1326 gc_prologue(true);
1327 increment_total_collections(true /* full gc */);
1328 increment_old_marking_cycles_started();
1329
1330 assert(used() == recalculate_used(), "Should be equal");
1331
1332 verify_before_gc();
1333
1334 pre_full_gc_dump(gc_timer);
1335
1336 COMPILER2_PRESENT(DerivedPointerTable::clear());
1337
1338 // Disable discovery and empty the discovered lists
1339 // for the CM ref processor.
1340 ref_processor_cm()->disable_discovery();
1341 ref_processor_cm()->abandon_partial_discovery();
1342 ref_processor_cm()->verify_no_references_recorded();
1343
1344 // Abandon current iterations of concurrent marking and concurrent
1345 // refinement, if any are in progress. We have to do this before
1346 // wait_until_scan_finished() below.
1347 concurrent_mark()->abort();
1348
1349 // Make sure we'll choose a new allocation region afterwards.
1350 release_mutator_alloc_region();
1351 abandon_gc_alloc_regions();
1352 g1_rem_set()->cleanupHRRS();
1353
1354 // We should call this after we retire any currently active alloc
1355 // regions so that all the ALLOC / RETIRE events are generated
1356 // before the start GC event.
1357 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1358
1359 // We may have added regions to the current incremental collection
1360 // set between the last GC or pause and now. We need to clear the
1361 // incremental collection set and then start rebuilding it afresh
1362 // after this full GC.
1363 abandon_collection_set(g1_policy()->inc_cset_head());
1364 g1_policy()->clear_incremental_cset();
1365 g1_policy()->stop_incremental_cset_building();
1366
1367 tear_down_region_sets(false /* free_list_only */);
1368 g1_policy()->set_gcs_are_young(true);
1369
1370 // See the comments in g1CollectedHeap.hpp and
1371 // G1CollectedHeap::ref_processing_init() about
1372 // how reference processing currently works in G1.
1373
1374 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1375 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1376
1377 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1378 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1379
1380 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1381 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1382
1383 // Do collection work
1384 {
1385 HandleMark hm; // Discard invalid handles created during gc
1386 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1387 }
1388
1389 assert(free_regions() == 0, "we should not have added any free regions");
1390 rebuild_region_sets(false /* free_list_only */);
1391
1392 // Enqueue any discovered reference objects that have
1393 // not been removed from the discovered lists.
1394 ref_processor_stw()->enqueue_discovered_references();
1395
1396 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1397
1398 MemoryService::track_memory_usage();
1399
1400 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1401 ref_processor_stw()->verify_no_references_recorded();
1402
1403 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1404 ClassLoaderDataGraph::purge();
1405 MetaspaceAux::verify_metrics();
1406
1407 // Note: since we've just done a full GC, concurrent
1408 // marking is no longer active. Therefore we need not
1409 // re-enable reference discovery for the CM ref processor.
1410 // That will be done at the start of the next marking cycle.
1411 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1412 ref_processor_cm()->verify_no_references_recorded();
1413
1414 reset_gc_time_stamp();
1415 // Since everything potentially moved, we will clear all remembered
1416 // sets, and clear all cards. Later we will rebuild remembered
1417 // sets. We will also reset the GC time stamps of the regions.
1418 clear_rsets_post_compaction();
1419 check_gc_time_stamps();
1420
1421 // Resize the heap if necessary.
1422 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1423
1424 if (_hr_printer.is_active()) {
1425 // We should do this after we potentially resize the heap so
1426 // that all the COMMIT / UNCOMMIT events are generated before
1427 // the end GC event.
1428
1429 print_hrs_post_compaction();
1430 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1431 }
1432
1433 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1434 if (hot_card_cache->use_cache()) {
1435 hot_card_cache->reset_card_counts();
1436 hot_card_cache->reset_hot_cache();
1437 }
1438
1439 // Rebuild remembered sets of all regions.
1440 if (G1CollectedHeap::use_parallel_gc_threads()) {
1441 uint n_workers =
1442 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1443 workers()->active_workers(),
1444 Threads::number_of_non_daemon_threads());
1445 assert(UseDynamicNumberOfGCThreads ||
1446 n_workers == workers()->total_workers(),
1447 "If not dynamic should be using all the workers");
1448 workers()->set_active_workers(n_workers);
1449 // Set parallel threads in the heap (_n_par_threads) only
1450 // before a parallel phase and always reset it to 0 after
1451 // the phase so that the number of parallel threads does
1452 // no get carried forward to a serial phase where there
1453 // may be code that is "possibly_parallel".
1454 set_par_threads(n_workers);
1455
1456 ParRebuildRSTask rebuild_rs_task(this);
1457 assert(check_heap_region_claim_values(
1458 HeapRegion::InitialClaimValue), "sanity check");
1459 assert(UseDynamicNumberOfGCThreads ||
1460 workers()->active_workers() == workers()->total_workers(),
1461 "Unless dynamic should use total workers");
1462 // Use the most recent number of active workers
1463 assert(workers()->active_workers() > 0,
1464 "Active workers not properly set");
1465 set_par_threads(workers()->active_workers());
1466 workers()->run_task(&rebuild_rs_task);
1467 set_par_threads(0);
1468 assert(check_heap_region_claim_values(
1469 HeapRegion::RebuildRSClaimValue), "sanity check");
1470 reset_heap_region_claim_values();
1471 } else {
1472 RebuildRSOutOfRegionClosure rebuild_rs(this);
1473 heap_region_iterate(&rebuild_rs);
1474 }
1475
1476 // Rebuild the strong code root lists for each region
1477 rebuild_strong_code_roots();
1478
1479 if (true) { // FIXME
1480 MetaspaceGC::compute_new_size();
1481 }
1482
1483 #ifdef TRACESPINNING
1484 ParallelTaskTerminator::print_termination_counts();
1485 #endif
1486
1487 // Discard all rset updates
1488 JavaThread::dirty_card_queue_set().abandon_logs();
1489 assert(!G1DeferredRSUpdate
1490 || (G1DeferredRSUpdate &&
1491 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1492
1493 _young_list->reset_sampled_info();
1494 // At this point there should be no regions in the
1495 // entire heap tagged as young.
1496 assert(check_young_list_empty(true /* check_heap */),
1497 "young list should be empty at this point");
1498
1499 // Update the number of full collections that have been completed.
1500 increment_old_marking_cycles_completed(false /* concurrent */);
1501
1502 _hrs.verify_optional();
1503 verify_region_sets_optional();
1504
1505 verify_after_gc();
1506
1507 // Start a new incremental collection set for the next pause
1508 assert(g1_policy()->collection_set() == NULL, "must be");
1509 g1_policy()->start_incremental_cset_building();
1510
1511 clear_cset_fast_test();
1512
1513 init_mutator_alloc_region();
1514
1515 double end = os::elapsedTime();
1516 g1_policy()->record_full_collection_end();
1517
1518 if (G1Log::fine()) {
1519 g1_policy()->print_heap_transition();
1520 }
1521
1522 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1523 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1524 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1525 // before any GC notifications are raised.
1526 g1mm()->update_sizes();
1527
1528 gc_epilogue(true);
1529 }
1530
1531 if (G1Log::finer()) {
1532 g1_policy()->print_detailed_heap_transition(true /* full */);
1533 }
1534
1535 print_heap_after_gc();
1536 trace_heap_after_gc(gc_tracer);
1537
1538 post_full_gc_dump(gc_timer);
1539
1540 gc_timer->register_gc_end();
1541 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1542 }
1543
1544 return true;
1545 }
1546
1547 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1548 // do_collection() will return whether it succeeded in performing
1549 // the GC. Currently, there is no facility on the
1550 // do_full_collection() API to notify the caller than the collection
1551 // did not succeed (e.g., because it was locked out by the GC
1552 // locker). So, right now, we'll ignore the return value.
1553 bool dummy = do_collection(true, /* explicit_gc */
1554 clear_all_soft_refs,
1555 0 /* word_size */);
1556 }
1557
1558 // This code is mostly copied from TenuredGeneration.
1559 void
1560 G1CollectedHeap::
1561 resize_if_necessary_after_full_collection(size_t word_size) {
1562 // Include the current allocation, if any, and bytes that will be
1563 // pre-allocated to support collections, as "used".
1564 const size_t used_after_gc = used();
1565 const size_t capacity_after_gc = capacity();
1566 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1567
1568 // This is enforced in arguments.cpp.
1569 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1570 "otherwise the code below doesn't make sense");
1571
1572 // We don't have floating point command-line arguments
1573 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1574 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1575 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1576 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1577
1578 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1579 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1580
1581 // We have to be careful here as these two calculations can overflow
1582 // 32-bit size_t's.
1583 double used_after_gc_d = (double) used_after_gc;
1584 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1585 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1586
1587 // Let's make sure that they are both under the max heap size, which
1588 // by default will make them fit into a size_t.
1589 double desired_capacity_upper_bound = (double) max_heap_size;
1590 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1591 desired_capacity_upper_bound);
1592 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1593 desired_capacity_upper_bound);
1594
1595 // We can now safely turn them into size_t's.
1596 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1597 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1598
1599 // This assert only makes sense here, before we adjust them
1600 // with respect to the min and max heap size.
1601 assert(minimum_desired_capacity <= maximum_desired_capacity,
1602 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1603 "maximum_desired_capacity = "SIZE_FORMAT,
1604 minimum_desired_capacity, maximum_desired_capacity));
1605
1606 // Should not be greater than the heap max size. No need to adjust
1607 // it with respect to the heap min size as it's a lower bound (i.e.,
1608 // we'll try to make the capacity larger than it, not smaller).
1609 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1610 // Should not be less than the heap min size. No need to adjust it
1611 // with respect to the heap max size as it's an upper bound (i.e.,
1612 // we'll try to make the capacity smaller than it, not greater).
1613 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1614
1615 if (capacity_after_gc < minimum_desired_capacity) {
1616 // Don't expand unless it's significant
1617 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1618 ergo_verbose4(ErgoHeapSizing,
1619 "attempt heap expansion",
1620 ergo_format_reason("capacity lower than "
1621 "min desired capacity after Full GC")
1622 ergo_format_byte("capacity")
1623 ergo_format_byte("occupancy")
1624 ergo_format_byte_perc("min desired capacity"),
1625 capacity_after_gc, used_after_gc,
1626 minimum_desired_capacity, (double) MinHeapFreeRatio);
1627 expand(expand_bytes);
1628
1629 // No expansion, now see if we want to shrink
1630 } else if (capacity_after_gc > maximum_desired_capacity) {
1631 // Capacity too large, compute shrinking size
1632 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1633 ergo_verbose4(ErgoHeapSizing,
1634 "attempt heap shrinking",
1635 ergo_format_reason("capacity higher than "
1636 "max desired capacity after Full GC")
1637 ergo_format_byte("capacity")
1638 ergo_format_byte("occupancy")
1639 ergo_format_byte_perc("max desired capacity"),
1640 capacity_after_gc, used_after_gc,
1641 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1642 shrink(shrink_bytes);
1643 }
1644 }
1645
1646
1647 HeapWord*
1648 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1649 bool* succeeded) {
1650 assert_at_safepoint(true /* should_be_vm_thread */);
1651
1652 *succeeded = true;
1653 // Let's attempt the allocation first.
1654 HeapWord* result =
1655 attempt_allocation_at_safepoint(word_size,
1656 false /* expect_null_mutator_alloc_region */);
1657 if (result != NULL) {
1658 assert(*succeeded, "sanity");
1659 return result;
1660 }
1661
1662 // In a G1 heap, we're supposed to keep allocation from failing by
1663 // incremental pauses. Therefore, at least for now, we'll favor
1664 // expansion over collection. (This might change in the future if we can
1665 // do something smarter than full collection to satisfy a failed alloc.)
1666 result = expand_and_allocate(word_size);
1667 if (result != NULL) {
1668 assert(*succeeded, "sanity");
1669 return result;
1670 }
1671
1672 // Expansion didn't work, we'll try to do a Full GC.
1673 bool gc_succeeded = do_collection(false, /* explicit_gc */
1674 false, /* clear_all_soft_refs */
1675 word_size);
1676 if (!gc_succeeded) {
1677 *succeeded = false;
1678 return NULL;
1679 }
1680
1681 // Retry the allocation
1682 result = attempt_allocation_at_safepoint(word_size,
1683 true /* expect_null_mutator_alloc_region */);
1684 if (result != NULL) {
1685 assert(*succeeded, "sanity");
1686 return result;
1687 }
1688
1689 // Then, try a Full GC that will collect all soft references.
1690 gc_succeeded = do_collection(false, /* explicit_gc */
1691 true, /* clear_all_soft_refs */
1692 word_size);
1693 if (!gc_succeeded) {
1694 *succeeded = false;
1695 return NULL;
1696 }
1697
1698 // Retry the allocation once more
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 assert(!collector_policy()->should_clear_all_soft_refs(),
1707 "Flag should have been handled and cleared prior to this point");
1708
1709 // What else? We might try synchronous finalization later. If the total
1710 // space available is large enough for the allocation, then a more
1711 // complete compaction phase than we've tried so far might be
1712 // appropriate.
1713 assert(*succeeded, "sanity");
1714 return NULL;
1715 }
1716
1717 // Attempting to expand the heap sufficiently
1718 // to support an allocation of the given "word_size". If
1719 // successful, perform the allocation and return the address of the
1720 // allocated block, or else "NULL".
1721
1722 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1723 assert_at_safepoint(true /* should_be_vm_thread */);
1724
1725 verify_region_sets_optional();
1726
1727 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1728 ergo_verbose1(ErgoHeapSizing,
1729 "attempt heap expansion",
1730 ergo_format_reason("allocation request failed")
1731 ergo_format_byte("allocation request"),
1732 word_size * HeapWordSize);
1733 if (expand(expand_bytes)) {
1734 _hrs.verify_optional();
1735 verify_region_sets_optional();
1736 return attempt_allocation_at_safepoint(word_size,
1737 false /* expect_null_mutator_alloc_region */);
1738 }
1739 return NULL;
1740 }
1741
1742 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1743 HeapWord* new_end) {
1744 assert(old_end != new_end, "don't call this otherwise");
1745 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1746
1747 // Update the committed mem region.
1748 _g1_committed.set_end(new_end);
1749 // Tell the card table about the update.
1750 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1751 // Tell the BOT about the update.
1752 _bot_shared->resize(_g1_committed.word_size());
1753 // Tell the hot card cache about the update
1754 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1755 }
1756
1757 bool G1CollectedHeap::expand(size_t expand_bytes) {
1758 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1759 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1760 HeapRegion::GrainBytes);
1761 ergo_verbose2(ErgoHeapSizing,
1762 "expand the heap",
1763 ergo_format_byte("requested expansion amount")
1764 ergo_format_byte("attempted expansion amount"),
1765 expand_bytes, aligned_expand_bytes);
1766
1767 if (_g1_storage.uncommitted_size() == 0) {
1768 ergo_verbose0(ErgoHeapSizing,
1769 "did not expand the heap",
1770 ergo_format_reason("heap already fully expanded"));
1771 return false;
1772 }
1773
1774 // First commit the memory.
1775 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1776 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1777 if (successful) {
1778 // Then propagate this update to the necessary data structures.
1779 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1780 update_committed_space(old_end, new_end);
1781
1782 FreeRegionList expansion_list("Local Expansion List");
1783 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1784 assert(mr.start() == old_end, "post-condition");
1785 // mr might be a smaller region than what was requested if
1786 // expand_by() was unable to allocate the HeapRegion instances
1787 assert(mr.end() <= new_end, "post-condition");
1788
1789 size_t actual_expand_bytes = mr.byte_size();
1790 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1791 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1792 "post-condition");
1793 if (actual_expand_bytes < aligned_expand_bytes) {
1794 // We could not expand _hrs to the desired size. In this case we
1795 // need to shrink the committed space accordingly.
1796 assert(mr.end() < new_end, "invariant");
1797
1798 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1799 // First uncommit the memory.
1800 _g1_storage.shrink_by(diff_bytes);
1801 // Then propagate this update to the necessary data structures.
1802 update_committed_space(new_end, mr.end());
1803 }
1804 _free_list.add_as_tail(&expansion_list);
1805
1806 if (_hr_printer.is_active()) {
1807 HeapWord* curr = mr.start();
1808 while (curr < mr.end()) {
1809 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1810 _hr_printer.commit(curr, curr_end);
1811 curr = curr_end;
1812 }
1813 assert(curr == mr.end(), "post-condition");
1814 }
1815 g1_policy()->record_new_heap_size(n_regions());
1816 } else {
1817 ergo_verbose0(ErgoHeapSizing,
1818 "did not expand the heap",
1819 ergo_format_reason("heap expansion operation failed"));
1820 // The expansion of the virtual storage space was unsuccessful.
1821 // Let's see if it was because we ran out of swap.
1822 if (G1ExitOnExpansionFailure &&
1823 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1824 // We had head room...
1825 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1826 }
1827 }
1828 return successful;
1829 }
1830
1831 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1832 size_t aligned_shrink_bytes =
1833 ReservedSpace::page_align_size_down(shrink_bytes);
1834 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1835 HeapRegion::GrainBytes);
1836 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1837
1838 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1839 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1840 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1841
1842 ergo_verbose3(ErgoHeapSizing,
1843 "shrink the heap",
1844 ergo_format_byte("requested shrinking amount")
1845 ergo_format_byte("aligned shrinking amount")
1846 ergo_format_byte("attempted shrinking amount"),
1847 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1848 if (num_regions_removed > 0) {
1849 _g1_storage.shrink_by(shrunk_bytes);
1850 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1851
1852 if (_hr_printer.is_active()) {
1853 HeapWord* curr = old_end;
1854 while (curr > new_end) {
1855 HeapWord* curr_end = curr;
1856 curr -= HeapRegion::GrainWords;
1857 _hr_printer.uncommit(curr, curr_end);
1858 }
1859 }
1860
1861 _expansion_regions += num_regions_removed;
1862 update_committed_space(old_end, new_end);
1863 HeapRegionRemSet::shrink_heap(n_regions());
1864 g1_policy()->record_new_heap_size(n_regions());
1865 } else {
1866 ergo_verbose0(ErgoHeapSizing,
1867 "did not shrink the heap",
1868 ergo_format_reason("heap shrinking operation failed"));
1869 }
1870 }
1871
1872 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1873 verify_region_sets_optional();
1874
1875 // We should only reach here at the end of a Full GC which means we
1876 // should not not be holding to any GC alloc regions. The method
1877 // below will make sure of that and do any remaining clean up.
1878 abandon_gc_alloc_regions();
1879
1880 // Instead of tearing down / rebuilding the free lists here, we
1881 // could instead use the remove_all_pending() method on free_list to
1882 // remove only the ones that we need to remove.
1883 tear_down_region_sets(true /* free_list_only */);
1884 shrink_helper(shrink_bytes);
1885 rebuild_region_sets(true /* free_list_only */);
1886
1887 _hrs.verify_optional();
1888 verify_region_sets_optional();
1889 }
1890
1891 // Public methods.
1892
1893 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1894 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1895 #endif // _MSC_VER
1896
1897
1898 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1899 SharedHeap(policy_),
1900 _g1_policy(policy_),
1901 _dirty_card_queue_set(false),
1902 _into_cset_dirty_card_queue_set(false),
1903 _is_alive_closure_cm(this),
1904 _is_alive_closure_stw(this),
1905 _ref_processor_cm(NULL),
1906 _ref_processor_stw(NULL),
1907 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1908 _bot_shared(NULL),
1909 _evac_failure_scan_stack(NULL),
1910 _mark_in_progress(false),
1911 _cg1r(NULL), _summary_bytes_used(0),
1912 _g1mm(NULL),
1913 _refine_cte_cl(NULL),
1914 _full_collection(false),
1915 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1916 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1917 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1918 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1919 _free_regions_coming(false),
1920 _young_list(new YoungList(this)),
1921 _gc_time_stamp(0),
1922 _retained_old_gc_alloc_region(NULL),
1923 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1924 _old_plab_stats(OldPLABSize, PLABWeight),
1925 _expand_heap_after_alloc_failure(true),
1926 _surviving_young_words(NULL),
1927 _old_marking_cycles_started(0),
1928 _old_marking_cycles_completed(0),
1929 _concurrent_cycle_started(false),
1930 _in_cset_fast_test(),
1931 _dirty_cards_region_list(NULL),
1932 _worker_cset_start_region(NULL),
1933 _worker_cset_start_region_time_stamp(NULL),
1934 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1935 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1936 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1937 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1938
1939 _g1h = this;
1940 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1941 vm_exit_during_initialization("Failed necessary allocation.");
1942 }
1943
1944 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1945
1946 int n_queues = MAX2((int)ParallelGCThreads, 1);
1947 _task_queues = new RefToScanQueueSet(n_queues);
1948
1949 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1950 assert(n_rem_sets > 0, "Invariant.");
1951
1952 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1953 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1954 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1955
1956 for (int i = 0; i < n_queues; i++) {
1957 RefToScanQueue* q = new RefToScanQueue();
1958 q->initialize();
1959 _task_queues->register_queue(i, q);
1960 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1961 }
1962 clear_cset_start_regions();
1963
1964 // Initialize the G1EvacuationFailureALot counters and flags.
1965 NOT_PRODUCT(reset_evacuation_should_fail();)
1966
1967 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1968 }
1969
1970 jint G1CollectedHeap::initialize() {
1971 CollectedHeap::pre_initialize();
1972 os::enable_vtime();
1973
1974 G1Log::init();
1975
1976 // Necessary to satisfy locking discipline assertions.
1977
1978 MutexLocker x(Heap_lock);
1979
1980 // We have to initialize the printer before committing the heap, as
1981 // it will be used then.
1982 _hr_printer.set_active(G1PrintHeapRegions);
1983
1984 // While there are no constraints in the GC code that HeapWordSize
1985 // be any particular value, there are multiple other areas in the
1986 // system which believe this to be true (e.g. oop->object_size in some
1987 // cases incorrectly returns the size in wordSize units rather than
1988 // HeapWordSize).
1989 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1990
1991 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1992 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1993 size_t heap_alignment = collector_policy()->heap_alignment();
1994
1995 // Ensure that the sizes are properly aligned.
1996 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1997 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1998 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1999
2000 _refine_cte_cl = new RefineCardTableEntryClosure();
2001
2002 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2003
2004 // Reserve the maximum.
2005
2006 // When compressed oops are enabled, the preferred heap base
2007 // is calculated by subtracting the requested size from the
2008 // 32Gb boundary and using the result as the base address for
2009 // heap reservation. If the requested size is not aligned to
2010 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2011 // into the ReservedHeapSpace constructor) then the actual
2012 // base of the reserved heap may end up differing from the
2013 // address that was requested (i.e. the preferred heap base).
2014 // If this happens then we could end up using a non-optimal
2015 // compressed oops mode.
2016
2017 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2018 heap_alignment);
2019
2020 // It is important to do this in a way such that concurrent readers can't
2021 // temporarily think something is in the heap. (I've actually seen this
2022 // happen in asserts: DLD.)
2023 _reserved.set_word_size(0);
2024 _reserved.set_start((HeapWord*)heap_rs.base());
2025 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2026
2027 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2028
2029 // Create the gen rem set (and barrier set) for the entire reserved region.
2030 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2031 set_barrier_set(rem_set()->bs());
2032 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2033 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2034 return JNI_ENOMEM;
2035 }
2036
2037 // Also create a G1 rem set.
2038 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2039
2040 // Carve out the G1 part of the heap.
2041
2042 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2043 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2044 g1_rs.size()/HeapWordSize);
2045
2046 _g1_storage.initialize(g1_rs, 0);
2047 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2048 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2049 (HeapWord*) _g1_reserved.end());
2050 assert(_hrs.max_length() == _expansion_regions,
2051 err_msg("max length: %u expansion regions: %u",
2052 _hrs.max_length(), _expansion_regions));
2053
2054 // Do later initialization work for concurrent refinement.
2055 _cg1r->init();
2056
2057 // 6843694 - ensure that the maximum region index can fit
2058 // in the remembered set structures.
2059 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2060 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2061
2062 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2063 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2064 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2065 "too many cards per region");
2066
2067 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2068
2069 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2070 heap_word_size(init_byte_size));
2071
2072 _g1h = this;
2073
2074 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2075
2076 // Create the ConcurrentMark data structure and thread.
2077 // (Must do this late, so that "max_regions" is defined.)
2078 _cm = new ConcurrentMark(this, heap_rs);
2079 if (_cm == NULL || !_cm->completed_initialization()) {
2080 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2081 return JNI_ENOMEM;
2082 }
2083 _cmThread = _cm->cmThread();
2084
2085 // Initialize the from_card cache structure of HeapRegionRemSet.
2086 HeapRegionRemSet::init_heap(max_regions());
2087
2088 // Now expand into the initial heap size.
2089 if (!expand(init_byte_size)) {
2090 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2091 return JNI_ENOMEM;
2092 }
2093
2094 // Perform any initialization actions delegated to the policy.
2095 g1_policy()->init();
2096
2097 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2098 SATB_Q_FL_lock,
2099 G1SATBProcessCompletedThreshold,
2100 Shared_SATB_Q_lock);
2101
2102 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2103 DirtyCardQ_CBL_mon,
2104 DirtyCardQ_FL_lock,
2105 concurrent_g1_refine()->yellow_zone(),
2106 concurrent_g1_refine()->red_zone(),
2107 Shared_DirtyCardQ_lock);
2108
2109 if (G1DeferredRSUpdate) {
2110 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2111 DirtyCardQ_CBL_mon,
2112 DirtyCardQ_FL_lock,
2113 -1, // never trigger processing
2114 -1, // no limit on length
2115 Shared_DirtyCardQ_lock,
2116 &JavaThread::dirty_card_queue_set());
2117 }
2118
2119 // Initialize the card queue set used to hold cards containing
2120 // references into the collection set.
2121 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2122 DirtyCardQ_CBL_mon,
2123 DirtyCardQ_FL_lock,
2124 -1, // never trigger processing
2125 -1, // no limit on length
2126 Shared_DirtyCardQ_lock,
2127 &JavaThread::dirty_card_queue_set());
2128
2129 // In case we're keeping closure specialization stats, initialize those
2130 // counts and that mechanism.
2131 SpecializationStats::clear();
2132
2133 // Here we allocate the dummy full region that is required by the
2134 // G1AllocRegion class. If we don't pass an address in the reserved
2135 // space here, lots of asserts fire.
2136
2137 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2138 _g1_reserved.start());
2139 // We'll re-use the same region whether the alloc region will
2140 // require BOT updates or not and, if it doesn't, then a non-young
2141 // region will complain that it cannot support allocations without
2142 // BOT updates. So we'll tag the dummy region as young to avoid that.
2143 dummy_region->set_young();
2144 // Make sure it's full.
2145 dummy_region->set_top(dummy_region->end());
2146 G1AllocRegion::setup(this, dummy_region);
2147
2148 init_mutator_alloc_region();
2149
2150 // Do create of the monitoring and management support so that
2151 // values in the heap have been properly initialized.
2152 _g1mm = new G1MonitoringSupport(this);
2153
2154 G1StringDedup::initialize();
2155
2156 return JNI_OK;
2157 }
2158
2159 void G1CollectedHeap::stop() {
2160 // Abort any ongoing concurrent root region scanning and stop all
2161 // concurrent threads. We do this to make sure these threads do
2162 // not continue to execute and access resources (e.g. gclog_or_tty)
2163 // that are destroyed during shutdown.
2164 _cm->root_regions()->abort();
2165 _cm->root_regions()->wait_until_scan_finished();
2166 stop_conc_gc_threads();
2167 }
2168
2169 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2170 return HeapRegion::max_region_size();
2171 }
2172
2173 void G1CollectedHeap::ref_processing_init() {
2174 // Reference processing in G1 currently works as follows:
2175 //
2176 // * There are two reference processor instances. One is
2177 // used to record and process discovered references
2178 // during concurrent marking; the other is used to
2179 // record and process references during STW pauses
2180 // (both full and incremental).
2181 // * Both ref processors need to 'span' the entire heap as
2182 // the regions in the collection set may be dotted around.
2183 //
2184 // * For the concurrent marking ref processor:
2185 // * Reference discovery is enabled at initial marking.
2186 // * Reference discovery is disabled and the discovered
2187 // references processed etc during remarking.
2188 // * Reference discovery is MT (see below).
2189 // * Reference discovery requires a barrier (see below).
2190 // * Reference processing may or may not be MT
2191 // (depending on the value of ParallelRefProcEnabled
2192 // and ParallelGCThreads).
2193 // * A full GC disables reference discovery by the CM
2194 // ref processor and abandons any entries on it's
2195 // discovered lists.
2196 //
2197 // * For the STW processor:
2198 // * Non MT discovery is enabled at the start of a full GC.
2199 // * Processing and enqueueing during a full GC is non-MT.
2200 // * During a full GC, references are processed after marking.
2201 //
2202 // * Discovery (may or may not be MT) is enabled at the start
2203 // of an incremental evacuation pause.
2204 // * References are processed near the end of a STW evacuation pause.
2205 // * For both types of GC:
2206 // * Discovery is atomic - i.e. not concurrent.
2207 // * Reference discovery will not need a barrier.
2208
2209 SharedHeap::ref_processing_init();
2210 MemRegion mr = reserved_region();
2211
2212 // Concurrent Mark ref processor
2213 _ref_processor_cm =
2214 new ReferenceProcessor(mr, // span
2215 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2216 // mt processing
2217 (int) ParallelGCThreads,
2218 // degree of mt processing
2219 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2220 // mt discovery
2221 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2222 // degree of mt discovery
2223 false,
2224 // Reference discovery is not atomic
2225 &_is_alive_closure_cm,
2226 // is alive closure
2227 // (for efficiency/performance)
2228 true);
2229 // Setting next fields of discovered
2230 // lists requires a barrier.
2231
2232 // STW ref processor
2233 _ref_processor_stw =
2234 new ReferenceProcessor(mr, // span
2235 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2236 // mt processing
2237 MAX2((int)ParallelGCThreads, 1),
2238 // degree of mt processing
2239 (ParallelGCThreads > 1),
2240 // mt discovery
2241 MAX2((int)ParallelGCThreads, 1),
2242 // degree of mt discovery
2243 true,
2244 // Reference discovery is atomic
2245 &_is_alive_closure_stw,
2246 // is alive closure
2247 // (for efficiency/performance)
2248 false);
2249 // Setting next fields of discovered
2250 // lists does not require a barrier.
2251 }
2252
2253 size_t G1CollectedHeap::capacity() const {
2254 return _g1_committed.byte_size();
2255 }
2256
2257 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2258 assert(!hr->continuesHumongous(), "pre-condition");
2259 hr->reset_gc_time_stamp();
2260 if (hr->startsHumongous()) {
2261 uint first_index = hr->hrs_index() + 1;
2262 uint last_index = hr->last_hc_index();
2263 for (uint i = first_index; i < last_index; i += 1) {
2264 HeapRegion* chr = region_at(i);
2265 assert(chr->continuesHumongous(), "sanity");
2266 chr->reset_gc_time_stamp();
2267 }
2268 }
2269 }
2270
2271 #ifndef PRODUCT
2272 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2273 private:
2274 unsigned _gc_time_stamp;
2275 bool _failures;
2276
2277 public:
2278 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2279 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2280
2281 virtual bool doHeapRegion(HeapRegion* hr) {
2282 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2283 if (_gc_time_stamp != region_gc_time_stamp) {
2284 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2285 "expected %d", HR_FORMAT_PARAMS(hr),
2286 region_gc_time_stamp, _gc_time_stamp);
2287 _failures = true;
2288 }
2289 return false;
2290 }
2291
2292 bool failures() { return _failures; }
2293 };
2294
2295 void G1CollectedHeap::check_gc_time_stamps() {
2296 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2297 heap_region_iterate(&cl);
2298 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2299 }
2300 #endif // PRODUCT
2301
2302 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2303 DirtyCardQueue* into_cset_dcq,
2304 bool concurrent,
2305 uint worker_i) {
2306 // Clean cards in the hot card cache
2307 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2308 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2309
2310 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2311 int n_completed_buffers = 0;
2312 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2313 n_completed_buffers++;
2314 }
2315 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2316 dcqs.clear_n_completed_buffers();
2317 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2318 }
2319
2320
2321 // Computes the sum of the storage used by the various regions.
2322
2323 size_t G1CollectedHeap::used() const {
2324 assert(Heap_lock->owner() != NULL,
2325 "Should be owned on this thread's behalf.");
2326 size_t result = _summary_bytes_used;
2327 // Read only once in case it is set to NULL concurrently
2328 HeapRegion* hr = _mutator_alloc_region.get();
2329 if (hr != NULL)
2330 result += hr->used();
2331 return result;
2332 }
2333
2334 size_t G1CollectedHeap::used_unlocked() const {
2335 size_t result = _summary_bytes_used;
2336 return result;
2337 }
2338
2339 class SumUsedClosure: public HeapRegionClosure {
2340 size_t _used;
2341 public:
2342 SumUsedClosure() : _used(0) {}
2343 bool doHeapRegion(HeapRegion* r) {
2344 if (!r->continuesHumongous()) {
2345 _used += r->used();
2346 }
2347 return false;
2348 }
2349 size_t result() { return _used; }
2350 };
2351
2352 size_t G1CollectedHeap::recalculate_used() const {
2353 double recalculate_used_start = os::elapsedTime();
2354
2355 SumUsedClosure blk;
2356 heap_region_iterate(&blk);
2357
2358 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2359 return blk.result();
2360 }
2361
2362 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2363 switch (cause) {
2364 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2365 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2366 case GCCause::_g1_humongous_allocation: return true;
2367 default: return false;
2368 }
2369 }
2370
2371 #ifndef PRODUCT
2372 void G1CollectedHeap::allocate_dummy_regions() {
2373 // Let's fill up most of the region
2374 size_t word_size = HeapRegion::GrainWords - 1024;
2375 // And as a result the region we'll allocate will be humongous.
2376 guarantee(isHumongous(word_size), "sanity");
2377
2378 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2379 // Let's use the existing mechanism for the allocation
2380 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2381 if (dummy_obj != NULL) {
2382 MemRegion mr(dummy_obj, word_size);
2383 CollectedHeap::fill_with_object(mr);
2384 } else {
2385 // If we can't allocate once, we probably cannot allocate
2386 // again. Let's get out of the loop.
2387 break;
2388 }
2389 }
2390 }
2391 #endif // !PRODUCT
2392
2393 void G1CollectedHeap::increment_old_marking_cycles_started() {
2394 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2395 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2396 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2397 _old_marking_cycles_started, _old_marking_cycles_completed));
2398
2399 _old_marking_cycles_started++;
2400 }
2401
2402 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2403 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2404
2405 // We assume that if concurrent == true, then the caller is a
2406 // concurrent thread that was joined the Suspendible Thread
2407 // Set. If there's ever a cheap way to check this, we should add an
2408 // assert here.
2409
2410 // Given that this method is called at the end of a Full GC or of a
2411 // concurrent cycle, and those can be nested (i.e., a Full GC can
2412 // interrupt a concurrent cycle), the number of full collections
2413 // completed should be either one (in the case where there was no
2414 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2415 // behind the number of full collections started.
2416
2417 // This is the case for the inner caller, i.e. a Full GC.
2418 assert(concurrent ||
2419 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2420 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2421 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2422 "is inconsistent with _old_marking_cycles_completed = %u",
2423 _old_marking_cycles_started, _old_marking_cycles_completed));
2424
2425 // This is the case for the outer caller, i.e. the concurrent cycle.
2426 assert(!concurrent ||
2427 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2428 err_msg("for outer caller (concurrent cycle): "
2429 "_old_marking_cycles_started = %u "
2430 "is inconsistent with _old_marking_cycles_completed = %u",
2431 _old_marking_cycles_started, _old_marking_cycles_completed));
2432
2433 _old_marking_cycles_completed += 1;
2434
2435 // We need to clear the "in_progress" flag in the CM thread before
2436 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2437 // is set) so that if a waiter requests another System.gc() it doesn't
2438 // incorrectly see that a marking cycle is still in progress.
2439 if (concurrent) {
2440 _cmThread->clear_in_progress();
2441 }
2442
2443 // This notify_all() will ensure that a thread that called
2444 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2445 // and it's waiting for a full GC to finish will be woken up. It is
2446 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2447 FullGCCount_lock->notify_all();
2448 }
2449
2450 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2451 _concurrent_cycle_started = true;
2452 _gc_timer_cm->register_gc_start(start_time);
2453
2454 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2455 trace_heap_before_gc(_gc_tracer_cm);
2456 }
2457
2458 void G1CollectedHeap::register_concurrent_cycle_end() {
2459 if (_concurrent_cycle_started) {
2460 if (_cm->has_aborted()) {
2461 _gc_tracer_cm->report_concurrent_mode_failure();
2462 }
2463
2464 _gc_timer_cm->register_gc_end();
2465 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2466
2467 _concurrent_cycle_started = false;
2468 }
2469 }
2470
2471 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2472 if (_concurrent_cycle_started) {
2473 trace_heap_after_gc(_gc_tracer_cm);
2474 }
2475 }
2476
2477 G1YCType G1CollectedHeap::yc_type() {
2478 bool is_young = g1_policy()->gcs_are_young();
2479 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2480 bool is_during_mark = mark_in_progress();
2481
2482 if (is_initial_mark) {
2483 return InitialMark;
2484 } else if (is_during_mark) {
2485 return DuringMark;
2486 } else if (is_young) {
2487 return Normal;
2488 } else {
2489 return Mixed;
2490 }
2491 }
2492
2493 void G1CollectedHeap::collect(GCCause::Cause cause) {
2494 assert_heap_not_locked();
2495
2496 unsigned int gc_count_before;
2497 unsigned int old_marking_count_before;
2498 bool retry_gc;
2499
2500 do {
2501 retry_gc = false;
2502
2503 {
2504 MutexLocker ml(Heap_lock);
2505
2506 // Read the GC count while holding the Heap_lock
2507 gc_count_before = total_collections();
2508 old_marking_count_before = _old_marking_cycles_started;
2509 }
2510
2511 if (should_do_concurrent_full_gc(cause)) {
2512 // Schedule an initial-mark evacuation pause that will start a
2513 // concurrent cycle. We're setting word_size to 0 which means that
2514 // we are not requesting a post-GC allocation.
2515 VM_G1IncCollectionPause op(gc_count_before,
2516 0, /* word_size */
2517 true, /* should_initiate_conc_mark */
2518 g1_policy()->max_pause_time_ms(),
2519 cause);
2520
2521 VMThread::execute(&op);
2522 if (!op.pause_succeeded()) {
2523 if (old_marking_count_before == _old_marking_cycles_started) {
2524 retry_gc = op.should_retry_gc();
2525 } else {
2526 // A Full GC happened while we were trying to schedule the
2527 // initial-mark GC. No point in starting a new cycle given
2528 // that the whole heap was collected anyway.
2529 }
2530
2531 if (retry_gc) {
2532 if (GC_locker::is_active_and_needs_gc()) {
2533 GC_locker::stall_until_clear();
2534 }
2535 }
2536 }
2537 } else {
2538 if (cause == GCCause::_gc_locker
2539 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2540
2541 // Schedule a standard evacuation pause. We're setting word_size
2542 // to 0 which means that we are not requesting a post-GC allocation.
2543 VM_G1IncCollectionPause op(gc_count_before,
2544 0, /* word_size */
2545 false, /* should_initiate_conc_mark */
2546 g1_policy()->max_pause_time_ms(),
2547 cause);
2548 VMThread::execute(&op);
2549 } else {
2550 // Schedule a Full GC.
2551 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2552 VMThread::execute(&op);
2553 }
2554 }
2555 } while (retry_gc);
2556 }
2557
2558 bool G1CollectedHeap::is_in(const void* p) const {
2559 if (_g1_committed.contains(p)) {
2560 // Given that we know that p is in the committed space,
2561 // heap_region_containing_raw() should successfully
2562 // return the containing region.
2563 HeapRegion* hr = heap_region_containing_raw(p);
2564 return hr->is_in(p);
2565 } else {
2566 return false;
2567 }
2568 }
2569
2570 // Iteration functions.
2571
2572 // Iterates an OopClosure over all ref-containing fields of objects
2573 // within a HeapRegion.
2574
2575 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2576 MemRegion _mr;
2577 ExtendedOopClosure* _cl;
2578 public:
2579 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2580 : _mr(mr), _cl(cl) {}
2581 bool doHeapRegion(HeapRegion* r) {
2582 if (!r->continuesHumongous()) {
2583 r->oop_iterate(_cl);
2584 }
2585 return false;
2586 }
2587 };
2588
2589 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2590 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2591 heap_region_iterate(&blk);
2592 }
2593
2594 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2595 IterateOopClosureRegionClosure blk(mr, cl);
2596 heap_region_iterate(&blk);
2597 }
2598
2599 // Iterates an ObjectClosure over all objects within a HeapRegion.
2600
2601 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2602 ObjectClosure* _cl;
2603 public:
2604 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2605 bool doHeapRegion(HeapRegion* r) {
2606 if (! r->continuesHumongous()) {
2607 r->object_iterate(_cl);
2608 }
2609 return false;
2610 }
2611 };
2612
2613 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2614 IterateObjectClosureRegionClosure blk(cl);
2615 heap_region_iterate(&blk);
2616 }
2617
2618 // Calls a SpaceClosure on a HeapRegion.
2619
2620 class SpaceClosureRegionClosure: public HeapRegionClosure {
2621 SpaceClosure* _cl;
2622 public:
2623 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2624 bool doHeapRegion(HeapRegion* r) {
2625 _cl->do_space(r);
2626 return false;
2627 }
2628 };
2629
2630 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2631 SpaceClosureRegionClosure blk(cl);
2632 heap_region_iterate(&blk);
2633 }
2634
2635 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2636 _hrs.iterate(cl);
2637 }
2638
2639 void
2640 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2641 uint worker_id,
2642 uint no_of_par_workers,
2643 jint claim_value) {
2644 const uint regions = n_regions();
2645 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2646 no_of_par_workers :
2647 1);
2648 assert(UseDynamicNumberOfGCThreads ||
2649 no_of_par_workers == workers()->total_workers(),
2650 "Non dynamic should use fixed number of workers");
2651 // try to spread out the starting points of the workers
2652 const HeapRegion* start_hr =
2653 start_region_for_worker(worker_id, no_of_par_workers);
2654 const uint start_index = start_hr->hrs_index();
2655
2656 // each worker will actually look at all regions
2657 for (uint count = 0; count < regions; ++count) {
2658 const uint index = (start_index + count) % regions;
2659 assert(0 <= index && index < regions, "sanity");
2660 HeapRegion* r = region_at(index);
2661 // we'll ignore "continues humongous" regions (we'll process them
2662 // when we come across their corresponding "start humongous"
2663 // region) and regions already claimed
2664 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2665 continue;
2666 }
2667 // OK, try to claim it
2668 if (r->claimHeapRegion(claim_value)) {
2669 // success!
2670 assert(!r->continuesHumongous(), "sanity");
2671 if (r->startsHumongous()) {
2672 // If the region is "starts humongous" we'll iterate over its
2673 // "continues humongous" first; in fact we'll do them
2674 // first. The order is important. In on case, calling the
2675 // closure on the "starts humongous" region might de-allocate
2676 // and clear all its "continues humongous" regions and, as a
2677 // result, we might end up processing them twice. So, we'll do
2678 // them first (notice: most closures will ignore them anyway) and
2679 // then we'll do the "starts humongous" region.
2680 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2681 HeapRegion* chr = region_at(ch_index);
2682
2683 // if the region has already been claimed or it's not
2684 // "continues humongous" we're done
2685 if (chr->claim_value() == claim_value ||
2686 !chr->continuesHumongous()) {
2687 break;
2688 }
2689
2690 // No one should have claimed it directly. We can given
2691 // that we claimed its "starts humongous" region.
2692 assert(chr->claim_value() != claim_value, "sanity");
2693 assert(chr->humongous_start_region() == r, "sanity");
2694
2695 if (chr->claimHeapRegion(claim_value)) {
2696 // we should always be able to claim it; no one else should
2697 // be trying to claim this region
2698
2699 bool res2 = cl->doHeapRegion(chr);
2700 assert(!res2, "Should not abort");
2701
2702 // Right now, this holds (i.e., no closure that actually
2703 // does something with "continues humongous" regions
2704 // clears them). We might have to weaken it in the future,
2705 // but let's leave these two asserts here for extra safety.
2706 assert(chr->continuesHumongous(), "should still be the case");
2707 assert(chr->humongous_start_region() == r, "sanity");
2708 } else {
2709 guarantee(false, "we should not reach here");
2710 }
2711 }
2712 }
2713
2714 assert(!r->continuesHumongous(), "sanity");
2715 bool res = cl->doHeapRegion(r);
2716 assert(!res, "Should not abort");
2717 }
2718 }
2719 }
2720
2721 class ResetClaimValuesClosure: public HeapRegionClosure {
2722 public:
2723 bool doHeapRegion(HeapRegion* r) {
2724 r->set_claim_value(HeapRegion::InitialClaimValue);
2725 return false;
2726 }
2727 };
2728
2729 void G1CollectedHeap::reset_heap_region_claim_values() {
2730 ResetClaimValuesClosure blk;
2731 heap_region_iterate(&blk);
2732 }
2733
2734 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2735 ResetClaimValuesClosure blk;
2736 collection_set_iterate(&blk);
2737 }
2738
2739 #ifdef ASSERT
2740 // This checks whether all regions in the heap have the correct claim
2741 // value. I also piggy-backed on this a check to ensure that the
2742 // humongous_start_region() information on "continues humongous"
2743 // regions is correct.
2744
2745 class CheckClaimValuesClosure : public HeapRegionClosure {
2746 private:
2747 jint _claim_value;
2748 uint _failures;
2749 HeapRegion* _sh_region;
2750
2751 public:
2752 CheckClaimValuesClosure(jint claim_value) :
2753 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2754 bool doHeapRegion(HeapRegion* r) {
2755 if (r->claim_value() != _claim_value) {
2756 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2757 "claim value = %d, should be %d",
2758 HR_FORMAT_PARAMS(r),
2759 r->claim_value(), _claim_value);
2760 ++_failures;
2761 }
2762 if (!r->isHumongous()) {
2763 _sh_region = NULL;
2764 } else if (r->startsHumongous()) {
2765 _sh_region = r;
2766 } else if (r->continuesHumongous()) {
2767 if (r->humongous_start_region() != _sh_region) {
2768 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2769 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2770 HR_FORMAT_PARAMS(r),
2771 r->humongous_start_region(),
2772 _sh_region);
2773 ++_failures;
2774 }
2775 }
2776 return false;
2777 }
2778 uint failures() { return _failures; }
2779 };
2780
2781 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2782 CheckClaimValuesClosure cl(claim_value);
2783 heap_region_iterate(&cl);
2784 return cl.failures() == 0;
2785 }
2786
2787 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2788 private:
2789 jint _claim_value;
2790 uint _failures;
2791
2792 public:
2793 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2794 _claim_value(claim_value), _failures(0) { }
2795
2796 uint failures() { return _failures; }
2797
2798 bool doHeapRegion(HeapRegion* hr) {
2799 assert(hr->in_collection_set(), "how?");
2800 assert(!hr->isHumongous(), "H-region in CSet");
2801 if (hr->claim_value() != _claim_value) {
2802 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2803 "claim value = %d, should be %d",
2804 HR_FORMAT_PARAMS(hr),
2805 hr->claim_value(), _claim_value);
2806 _failures += 1;
2807 }
2808 return false;
2809 }
2810 };
2811
2812 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2813 CheckClaimValuesInCSetHRClosure cl(claim_value);
2814 collection_set_iterate(&cl);
2815 return cl.failures() == 0;
2816 }
2817 #endif // ASSERT
2818
2819 // Clear the cached CSet starting regions and (more importantly)
2820 // the time stamps. Called when we reset the GC time stamp.
2821 void G1CollectedHeap::clear_cset_start_regions() {
2822 assert(_worker_cset_start_region != NULL, "sanity");
2823 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2824
2825 int n_queues = MAX2((int)ParallelGCThreads, 1);
2826 for (int i = 0; i < n_queues; i++) {
2827 _worker_cset_start_region[i] = NULL;
2828 _worker_cset_start_region_time_stamp[i] = 0;
2829 }
2830 }
2831
2832 // Given the id of a worker, obtain or calculate a suitable
2833 // starting region for iterating over the current collection set.
2834 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2835 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2836
2837 HeapRegion* result = NULL;
2838 unsigned gc_time_stamp = get_gc_time_stamp();
2839
2840 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2841 // Cached starting region for current worker was set
2842 // during the current pause - so it's valid.
2843 // Note: the cached starting heap region may be NULL
2844 // (when the collection set is empty).
2845 result = _worker_cset_start_region[worker_i];
2846 assert(result == NULL || result->in_collection_set(), "sanity");
2847 return result;
2848 }
2849
2850 // The cached entry was not valid so let's calculate
2851 // a suitable starting heap region for this worker.
2852
2853 // We want the parallel threads to start their collection
2854 // set iteration at different collection set regions to
2855 // avoid contention.
2856 // If we have:
2857 // n collection set regions
2858 // p threads
2859 // Then thread t will start at region floor ((t * n) / p)
2860
2861 result = g1_policy()->collection_set();
2862 if (G1CollectedHeap::use_parallel_gc_threads()) {
2863 uint cs_size = g1_policy()->cset_region_length();
2864 uint active_workers = workers()->active_workers();
2865 assert(UseDynamicNumberOfGCThreads ||
2866 active_workers == workers()->total_workers(),
2867 "Unless dynamic should use total workers");
2868
2869 uint end_ind = (cs_size * worker_i) / active_workers;
2870 uint start_ind = 0;
2871
2872 if (worker_i > 0 &&
2873 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2874 // Previous workers starting region is valid
2875 // so let's iterate from there
2876 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2877 result = _worker_cset_start_region[worker_i - 1];
2878 }
2879
2880 for (uint i = start_ind; i < end_ind; i++) {
2881 result = result->next_in_collection_set();
2882 }
2883 }
2884
2885 // Note: the calculated starting heap region may be NULL
2886 // (when the collection set is empty).
2887 assert(result == NULL || result->in_collection_set(), "sanity");
2888 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2889 "should be updated only once per pause");
2890 _worker_cset_start_region[worker_i] = result;
2891 OrderAccess::storestore();
2892 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2893 return result;
2894 }
2895
2896 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2897 uint no_of_par_workers) {
2898 uint worker_num =
2899 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2900 assert(UseDynamicNumberOfGCThreads ||
2901 no_of_par_workers == workers()->total_workers(),
2902 "Non dynamic should use fixed number of workers");
2903 const uint start_index = n_regions() * worker_i / worker_num;
2904 return region_at(start_index);
2905 }
2906
2907 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2908 HeapRegion* r = g1_policy()->collection_set();
2909 while (r != NULL) {
2910 HeapRegion* next = r->next_in_collection_set();
2911 if (cl->doHeapRegion(r)) {
2912 cl->incomplete();
2913 return;
2914 }
2915 r = next;
2916 }
2917 }
2918
2919 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2920 HeapRegionClosure *cl) {
2921 if (r == NULL) {
2922 // The CSet is empty so there's nothing to do.
2923 return;
2924 }
2925
2926 assert(r->in_collection_set(),
2927 "Start region must be a member of the collection set.");
2928 HeapRegion* cur = r;
2929 while (cur != NULL) {
2930 HeapRegion* next = cur->next_in_collection_set();
2931 if (cl->doHeapRegion(cur) && false) {
2932 cl->incomplete();
2933 return;
2934 }
2935 cur = next;
2936 }
2937 cur = g1_policy()->collection_set();
2938 while (cur != r) {
2939 HeapRegion* next = cur->next_in_collection_set();
2940 if (cl->doHeapRegion(cur) && false) {
2941 cl->incomplete();
2942 return;
2943 }
2944 cur = next;
2945 }
2946 }
2947
2948 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2949 return n_regions() > 0 ? region_at(0) : NULL;
2950 }
2951
2952
2953 Space* G1CollectedHeap::space_containing(const void* addr) const {
2954 Space* res = heap_region_containing(addr);
2955 return res;
2956 }
2957
2958 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2959 Space* sp = space_containing(addr);
2960 if (sp != NULL) {
2961 return sp->block_start(addr);
2962 }
2963 return NULL;
2964 }
2965
2966 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2967 Space* sp = space_containing(addr);
2968 assert(sp != NULL, "block_size of address outside of heap");
2969 return sp->block_size(addr);
2970 }
2971
2972 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2973 Space* sp = space_containing(addr);
2974 return sp->block_is_obj(addr);
2975 }
2976
2977 bool G1CollectedHeap::supports_tlab_allocation() const {
2978 return true;
2979 }
2980
2981 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2982 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2983 }
2984
2985 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2986 return young_list()->eden_used_bytes();
2987 }
2988
2989 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2990 // must be smaller than the humongous object limit.
2991 size_t G1CollectedHeap::max_tlab_size() const {
2992 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2993 }
2994
2995 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2996 // Return the remaining space in the cur alloc region, but not less than
2997 // the min TLAB size.
2998
2999 // Also, this value can be at most the humongous object threshold,
3000 // since we can't allow tlabs to grow big enough to accommodate
3001 // humongous objects.
3002
3003 HeapRegion* hr = _mutator_alloc_region.get();
3004 size_t max_tlab = max_tlab_size() * wordSize;
3005 if (hr == NULL) {
3006 return max_tlab;
3007 } else {
3008 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3009 }
3010 }
3011
3012 size_t G1CollectedHeap::max_capacity() const {
3013 return _g1_reserved.byte_size();
3014 }
3015
3016 jlong G1CollectedHeap::millis_since_last_gc() {
3017 // assert(false, "NYI");
3018 return 0;
3019 }
3020
3021 void G1CollectedHeap::prepare_for_verify() {
3022 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3023 ensure_parsability(false);
3024 }
3025 g1_rem_set()->prepare_for_verify();
3026 }
3027
3028 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3029 VerifyOption vo) {
3030 switch (vo) {
3031 case VerifyOption_G1UsePrevMarking:
3032 return hr->obj_allocated_since_prev_marking(obj);
3033 case VerifyOption_G1UseNextMarking:
3034 return hr->obj_allocated_since_next_marking(obj);
3035 case VerifyOption_G1UseMarkWord:
3036 return false;
3037 default:
3038 ShouldNotReachHere();
3039 }
3040 return false; // keep some compilers happy
3041 }
3042
3043 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3044 switch (vo) {
3045 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3046 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3047 case VerifyOption_G1UseMarkWord: return NULL;
3048 default: ShouldNotReachHere();
3049 }
3050 return NULL; // keep some compilers happy
3051 }
3052
3053 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3054 switch (vo) {
3055 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3056 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3057 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3058 default: ShouldNotReachHere();
3059 }
3060 return false; // keep some compilers happy
3061 }
3062
3063 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3064 switch (vo) {
3065 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3066 case VerifyOption_G1UseNextMarking: return "NTAMS";
3067 case VerifyOption_G1UseMarkWord: return "NONE";
3068 default: ShouldNotReachHere();
3069 }
3070 return NULL; // keep some compilers happy
3071 }
3072
3073 class VerifyRootsClosure: public OopClosure {
3074 private:
3075 G1CollectedHeap* _g1h;
3076 VerifyOption _vo;
3077 bool _failures;
3078 public:
3079 // _vo == UsePrevMarking -> use "prev" marking information,
3080 // _vo == UseNextMarking -> use "next" marking information,
3081 // _vo == UseMarkWord -> use mark word from object header.
3082 VerifyRootsClosure(VerifyOption vo) :
3083 _g1h(G1CollectedHeap::heap()),
3084 _vo(vo),
3085 _failures(false) { }
3086
3087 bool failures() { return _failures; }
3088
3089 template <class T> void do_oop_nv(T* p) {
3090 T heap_oop = oopDesc::load_heap_oop(p);
3091 if (!oopDesc::is_null(heap_oop)) {
3092 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3093 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3094 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3095 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3096 if (_vo == VerifyOption_G1UseMarkWord) {
3097 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3098 }
3099 obj->print_on(gclog_or_tty);
3100 _failures = true;
3101 }
3102 }
3103 }
3104
3105 void do_oop(oop* p) { do_oop_nv(p); }
3106 void do_oop(narrowOop* p) { do_oop_nv(p); }
3107 };
3108
3109 class G1VerifyCodeRootOopClosure: public OopClosure {
3110 G1CollectedHeap* _g1h;
3111 OopClosure* _root_cl;
3112 nmethod* _nm;
3113 VerifyOption _vo;
3114 bool _failures;
3115
3116 template <class T> void do_oop_work(T* p) {
3117 // First verify that this root is live
3118 _root_cl->do_oop(p);
3119
3120 if (!G1VerifyHeapRegionCodeRoots) {
3121 // We're not verifying the code roots attached to heap region.
3122 return;
3123 }
3124
3125 // Don't check the code roots during marking verification in a full GC
3126 if (_vo == VerifyOption_G1UseMarkWord) {
3127 return;
3128 }
3129
3130 // Now verify that the current nmethod (which contains p) is
3131 // in the code root list of the heap region containing the
3132 // object referenced by p.
3133
3134 T heap_oop = oopDesc::load_heap_oop(p);
3135 if (!oopDesc::is_null(heap_oop)) {
3136 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3137
3138 // Now fetch the region containing the object
3139 HeapRegion* hr = _g1h->heap_region_containing(obj);
3140 HeapRegionRemSet* hrrs = hr->rem_set();
3141 // Verify that the strong code root list for this region
3142 // contains the nmethod
3143 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3144 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3145 "from nmethod "PTR_FORMAT" not in strong "
3146 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3147 p, _nm, hr->bottom(), hr->end());
3148 _failures = true;
3149 }
3150 }
3151 }
3152
3153 public:
3154 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3155 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3156
3157 void do_oop(oop* p) { do_oop_work(p); }
3158 void do_oop(narrowOop* p) { do_oop_work(p); }
3159
3160 void set_nmethod(nmethod* nm) { _nm = nm; }
3161 bool failures() { return _failures; }
3162 };
3163
3164 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3165 G1VerifyCodeRootOopClosure* _oop_cl;
3166
3167 public:
3168 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3169 _oop_cl(oop_cl) {}
3170
3171 void do_code_blob(CodeBlob* cb) {
3172 nmethod* nm = cb->as_nmethod_or_null();
3173 if (nm != NULL) {
3174 _oop_cl->set_nmethod(nm);
3175 nm->oops_do(_oop_cl);
3176 }
3177 }
3178 };
3179
3180 class YoungRefCounterClosure : public OopClosure {
3181 G1CollectedHeap* _g1h;
3182 int _count;
3183 public:
3184 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3185 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3186 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3187
3188 int count() { return _count; }
3189 void reset_count() { _count = 0; };
3190 };
3191
3192 class VerifyKlassClosure: public KlassClosure {
3193 YoungRefCounterClosure _young_ref_counter_closure;
3194 OopClosure *_oop_closure;
3195 public:
3196 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3197 void do_klass(Klass* k) {
3198 k->oops_do(_oop_closure);
3199
3200 _young_ref_counter_closure.reset_count();
3201 k->oops_do(&_young_ref_counter_closure);
3202 if (_young_ref_counter_closure.count() > 0) {
3203 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3204 }
3205 }
3206 };
3207
3208 class VerifyLivenessOopClosure: public OopClosure {
3209 G1CollectedHeap* _g1h;
3210 VerifyOption _vo;
3211 public:
3212 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3213 _g1h(g1h), _vo(vo)
3214 { }
3215 void do_oop(narrowOop *p) { do_oop_work(p); }
3216 void do_oop( oop *p) { do_oop_work(p); }
3217
3218 template <class T> void do_oop_work(T *p) {
3219 oop obj = oopDesc::load_decode_heap_oop(p);
3220 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3221 "Dead object referenced by a not dead object");
3222 }
3223 };
3224
3225 class VerifyObjsInRegionClosure: public ObjectClosure {
3226 private:
3227 G1CollectedHeap* _g1h;
3228 size_t _live_bytes;
3229 HeapRegion *_hr;
3230 VerifyOption _vo;
3231 public:
3232 // _vo == UsePrevMarking -> use "prev" marking information,
3233 // _vo == UseNextMarking -> use "next" marking information,
3234 // _vo == UseMarkWord -> use mark word from object header.
3235 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3236 : _live_bytes(0), _hr(hr), _vo(vo) {
3237 _g1h = G1CollectedHeap::heap();
3238 }
3239 void do_object(oop o) {
3240 VerifyLivenessOopClosure isLive(_g1h, _vo);
3241 assert(o != NULL, "Huh?");
3242 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3243 // If the object is alive according to the mark word,
3244 // then verify that the marking information agrees.
3245 // Note we can't verify the contra-positive of the
3246 // above: if the object is dead (according to the mark
3247 // word), it may not be marked, or may have been marked
3248 // but has since became dead, or may have been allocated
3249 // since the last marking.
3250 if (_vo == VerifyOption_G1UseMarkWord) {
3251 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3252 }
3253
3254 o->oop_iterate_no_header(&isLive);
3255 if (!_hr->obj_allocated_since_prev_marking(o)) {
3256 size_t obj_size = o->size(); // Make sure we don't overflow
3257 _live_bytes += (obj_size * HeapWordSize);
3258 }
3259 }
3260 }
3261 size_t live_bytes() { return _live_bytes; }
3262 };
3263
3264 class PrintObjsInRegionClosure : public ObjectClosure {
3265 HeapRegion *_hr;
3266 G1CollectedHeap *_g1;
3267 public:
3268 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3269 _g1 = G1CollectedHeap::heap();
3270 };
3271
3272 void do_object(oop o) {
3273 if (o != NULL) {
3274 HeapWord *start = (HeapWord *) o;
3275 size_t word_sz = o->size();
3276 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3277 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3278 (void*) o, word_sz,
3279 _g1->isMarkedPrev(o),
3280 _g1->isMarkedNext(o),
3281 _hr->obj_allocated_since_prev_marking(o));
3282 HeapWord *end = start + word_sz;
3283 HeapWord *cur;
3284 int *val;
3285 for (cur = start; cur < end; cur++) {
3286 val = (int *) cur;
3287 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3288 }
3289 }
3290 }
3291 };
3292
3293 class VerifyRegionClosure: public HeapRegionClosure {
3294 private:
3295 bool _par;
3296 VerifyOption _vo;
3297 bool _failures;
3298 public:
3299 // _vo == UsePrevMarking -> use "prev" marking information,
3300 // _vo == UseNextMarking -> use "next" marking information,
3301 // _vo == UseMarkWord -> use mark word from object header.
3302 VerifyRegionClosure(bool par, VerifyOption vo)
3303 : _par(par),
3304 _vo(vo),
3305 _failures(false) {}
3306
3307 bool failures() {
3308 return _failures;
3309 }
3310
3311 bool doHeapRegion(HeapRegion* r) {
3312 if (!r->continuesHumongous()) {
3313 bool failures = false;
3314 r->verify(_vo, &failures);
3315 if (failures) {
3316 _failures = true;
3317 } else {
3318 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3319 r->object_iterate(¬_dead_yet_cl);
3320 if (_vo != VerifyOption_G1UseNextMarking) {
3321 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3322 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3323 "max_live_bytes "SIZE_FORMAT" "
3324 "< calculated "SIZE_FORMAT,
3325 r->bottom(), r->end(),
3326 r->max_live_bytes(),
3327 not_dead_yet_cl.live_bytes());
3328 _failures = true;
3329 }
3330 } else {
3331 // When vo == UseNextMarking we cannot currently do a sanity
3332 // check on the live bytes as the calculation has not been
3333 // finalized yet.
3334 }
3335 }
3336 }
3337 return false; // stop the region iteration if we hit a failure
3338 }
3339 };
3340
3341 // This is the task used for parallel verification of the heap regions
3342
3343 class G1ParVerifyTask: public AbstractGangTask {
3344 private:
3345 G1CollectedHeap* _g1h;
3346 VerifyOption _vo;
3347 bool _failures;
3348
3349 public:
3350 // _vo == UsePrevMarking -> use "prev" marking information,
3351 // _vo == UseNextMarking -> use "next" marking information,
3352 // _vo == UseMarkWord -> use mark word from object header.
3353 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3354 AbstractGangTask("Parallel verify task"),
3355 _g1h(g1h),
3356 _vo(vo),
3357 _failures(false) { }
3358
3359 bool failures() {
3360 return _failures;
3361 }
3362
3363 void work(uint worker_id) {
3364 HandleMark hm;
3365 VerifyRegionClosure blk(true, _vo);
3366 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3367 _g1h->workers()->active_workers(),
3368 HeapRegion::ParVerifyClaimValue);
3369 if (blk.failures()) {
3370 _failures = true;
3371 }
3372 }
3373 };
3374
3375 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3376 if (SafepointSynchronize::is_at_safepoint()) {
3377 assert(Thread::current()->is_VM_thread(),
3378 "Expected to be executed serially by the VM thread at this point");
3379
3380 if (!silent) { gclog_or_tty->print("Roots "); }
3381 VerifyRootsClosure rootsCl(vo);
3382 VerifyKlassClosure klassCl(this, &rootsCl);
3383
3384 // We apply the relevant closures to all the oops in the
3385 // system dictionary, class loader data graph and the string table.
3386 // Don't verify the code cache here, since it's verified below.
3387 const int so = SO_AllClasses | SO_Strings;
3388
3389 // Need cleared claim bits for the strong roots processing
3390 ClassLoaderDataGraph::clear_claimed_marks();
3391
3392 process_strong_roots(true, // activate StrongRootsScope
3393 ScanningOption(so), // roots scanning options
3394 &rootsCl,
3395 &klassCl
3396 );
3397
3398 // Verify the nmethods in the code cache.
3399 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3400 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3401 CodeCache::blobs_do(&blobsCl);
3402
3403 bool failures = rootsCl.failures() || codeRootsCl.failures();
3404
3405 if (vo != VerifyOption_G1UseMarkWord) {
3406 // If we're verifying during a full GC then the region sets
3407 // will have been torn down at the start of the GC. Therefore
3408 // verifying the region sets will fail. So we only verify
3409 // the region sets when not in a full GC.
3410 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3411 verify_region_sets();
3412 }
3413
3414 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3415 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3416 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3417 "sanity check");
3418
3419 G1ParVerifyTask task(this, vo);
3420 assert(UseDynamicNumberOfGCThreads ||
3421 workers()->active_workers() == workers()->total_workers(),
3422 "If not dynamic should be using all the workers");
3423 int n_workers = workers()->active_workers();
3424 set_par_threads(n_workers);
3425 workers()->run_task(&task);
3426 set_par_threads(0);
3427 if (task.failures()) {
3428 failures = true;
3429 }
3430
3431 // Checks that the expected amount of parallel work was done.
3432 // The implication is that n_workers is > 0.
3433 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3434 "sanity check");
3435
3436 reset_heap_region_claim_values();
3437
3438 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3439 "sanity check");
3440 } else {
3441 VerifyRegionClosure blk(false, vo);
3442 heap_region_iterate(&blk);
3443 if (blk.failures()) {
3444 failures = true;
3445 }
3446 }
3447 if (!silent) gclog_or_tty->print("RemSet ");
3448 rem_set()->verify();
3449
3450 if (G1StringDedup::is_enabled()) {
3451 if (!silent) gclog_or_tty->print("StrDedup ");
3452 G1StringDedup::verify();
3453 }
3454
3455 if (failures) {
3456 gclog_or_tty->print_cr("Heap:");
3457 // It helps to have the per-region information in the output to
3458 // help us track down what went wrong. This is why we call
3459 // print_extended_on() instead of print_on().
3460 print_extended_on(gclog_or_tty);
3461 gclog_or_tty->print_cr("");
3462 #ifndef PRODUCT
3463 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3464 concurrent_mark()->print_reachable("at-verification-failure",
3465 vo, false /* all */);
3466 }
3467 #endif
3468 gclog_or_tty->flush();
3469 }
3470 guarantee(!failures, "there should not have been any failures");
3471 } else {
3472 if (!silent) {
3473 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3474 if (G1StringDedup::is_enabled()) {
3475 gclog_or_tty->print(", StrDedup");
3476 }
3477 gclog_or_tty->print(") ");
3478 }
3479 }
3480 }
3481
3482 void G1CollectedHeap::verify(bool silent) {
3483 verify(silent, VerifyOption_G1UsePrevMarking);
3484 }
3485
3486 double G1CollectedHeap::verify(bool guard, const char* msg) {
3487 double verify_time_ms = 0.0;
3488
3489 if (guard && total_collections() >= VerifyGCStartAt) {
3490 double verify_start = os::elapsedTime();
3491 HandleMark hm; // Discard invalid handles created during verification
3492 prepare_for_verify();
3493 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3494 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3495 }
3496
3497 return verify_time_ms;
3498 }
3499
3500 void G1CollectedHeap::verify_before_gc() {
3501 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3502 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3503 }
3504
3505 void G1CollectedHeap::verify_after_gc() {
3506 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3507 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3508 }
3509
3510 class PrintRegionClosure: public HeapRegionClosure {
3511 outputStream* _st;
3512 public:
3513 PrintRegionClosure(outputStream* st) : _st(st) {}
3514 bool doHeapRegion(HeapRegion* r) {
3515 r->print_on(_st);
3516 return false;
3517 }
3518 };
3519
3520 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3521 const HeapRegion* hr,
3522 const VerifyOption vo) const {
3523 switch (vo) {
3524 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3525 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3526 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3527 default: ShouldNotReachHere();
3528 }
3529 return false; // keep some compilers happy
3530 }
3531
3532 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3533 const VerifyOption vo) const {
3534 switch (vo) {
3535 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3536 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3537 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3538 default: ShouldNotReachHere();
3539 }
3540 return false; // keep some compilers happy
3541 }
3542
3543 void G1CollectedHeap::print_on(outputStream* st) const {
3544 st->print(" %-20s", "garbage-first heap");
3545 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3546 capacity()/K, used_unlocked()/K);
3547 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3548 _g1_storage.low_boundary(),
3549 _g1_storage.high(),
3550 _g1_storage.high_boundary());
3551 st->cr();
3552 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3553 uint young_regions = _young_list->length();
3554 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3555 (size_t) young_regions * HeapRegion::GrainBytes / K);
3556 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3557 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3558 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3559 st->cr();
3560 MetaspaceAux::print_on(st);
3561 }
3562
3563 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3564 print_on(st);
3565
3566 // Print the per-region information.
3567 st->cr();
3568 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3569 "HS=humongous(starts), HC=humongous(continues), "
3570 "CS=collection set, F=free, TS=gc time stamp, "
3571 "PTAMS=previous top-at-mark-start, "
3572 "NTAMS=next top-at-mark-start)");
3573 PrintRegionClosure blk(st);
3574 heap_region_iterate(&blk);
3575 }
3576
3577 void G1CollectedHeap::print_on_error(outputStream* st) const {
3578 this->CollectedHeap::print_on_error(st);
3579
3580 if (_cm != NULL) {
3581 st->cr();
3582 _cm->print_on_error(st);
3583 }
3584 }
3585
3586 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3587 if (G1CollectedHeap::use_parallel_gc_threads()) {
3588 workers()->print_worker_threads_on(st);
3589 }
3590 _cmThread->print_on(st);
3591 st->cr();
3592 _cm->print_worker_threads_on(st);
3593 _cg1r->print_worker_threads_on(st);
3594 if (G1StringDedup::is_enabled()) {
3595 G1StringDedup::print_worker_threads_on(st);
3596 }
3597 }
3598
3599 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3600 if (G1CollectedHeap::use_parallel_gc_threads()) {
3601 workers()->threads_do(tc);
3602 }
3603 tc->do_thread(_cmThread);
3604 _cg1r->threads_do(tc);
3605 if (G1StringDedup::is_enabled()) {
3606 G1StringDedup::threads_do(tc);
3607 }
3608 }
3609
3610 void G1CollectedHeap::print_tracing_info() const {
3611 // We'll overload this to mean "trace GC pause statistics."
3612 if (TraceGen0Time || TraceGen1Time) {
3613 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3614 // to that.
3615 g1_policy()->print_tracing_info();
3616 }
3617 if (G1SummarizeRSetStats) {
3618 g1_rem_set()->print_summary_info();
3619 }
3620 if (G1SummarizeConcMark) {
3621 concurrent_mark()->print_summary_info();
3622 }
3623 g1_policy()->print_yg_surv_rate_info();
3624 SpecializationStats::print();
3625 }
3626
3627 #ifndef PRODUCT
3628 // Helpful for debugging RSet issues.
3629
3630 class PrintRSetsClosure : public HeapRegionClosure {
3631 private:
3632 const char* _msg;
3633 size_t _occupied_sum;
3634
3635 public:
3636 bool doHeapRegion(HeapRegion* r) {
3637 HeapRegionRemSet* hrrs = r->rem_set();
3638 size_t occupied = hrrs->occupied();
3639 _occupied_sum += occupied;
3640
3641 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3642 HR_FORMAT_PARAMS(r));
3643 if (occupied == 0) {
3644 gclog_or_tty->print_cr(" RSet is empty");
3645 } else {
3646 hrrs->print();
3647 }
3648 gclog_or_tty->print_cr("----------");
3649 return false;
3650 }
3651
3652 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3653 gclog_or_tty->cr();
3654 gclog_or_tty->print_cr("========================================");
3655 gclog_or_tty->print_cr(msg);
3656 gclog_or_tty->cr();
3657 }
3658
3659 ~PrintRSetsClosure() {
3660 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3661 gclog_or_tty->print_cr("========================================");
3662 gclog_or_tty->cr();
3663 }
3664 };
3665
3666 void G1CollectedHeap::print_cset_rsets() {
3667 PrintRSetsClosure cl("Printing CSet RSets");
3668 collection_set_iterate(&cl);
3669 }
3670
3671 void G1CollectedHeap::print_all_rsets() {
3672 PrintRSetsClosure cl("Printing All RSets");;
3673 heap_region_iterate(&cl);
3674 }
3675 #endif // PRODUCT
3676
3677 G1CollectedHeap* G1CollectedHeap::heap() {
3678 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3679 "not a garbage-first heap");
3680 return _g1h;
3681 }
3682
3683 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3684 // always_do_update_barrier = false;
3685 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3686 // Fill TLAB's and such
3687 accumulate_statistics_all_tlabs();
3688 ensure_parsability(true);
3689
3690 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3691 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3692 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3693 }
3694 }
3695
3696 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3697
3698 if (G1SummarizeRSetStats &&
3699 (G1SummarizeRSetStatsPeriod > 0) &&
3700 // we are at the end of the GC. Total collections has already been increased.
3701 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3702 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3703 }
3704
3705 // FIXME: what is this about?
3706 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3707 // is set.
3708 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3709 "derived pointer present"));
3710 // always_do_update_barrier = true;
3711
3712 resize_all_tlabs();
3713
3714 // We have just completed a GC. Update the soft reference
3715 // policy with the new heap occupancy
3716 Universe::update_heap_info_at_gc();
3717 }
3718
3719 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3720 unsigned int gc_count_before,
3721 bool* succeeded,
3722 GCCause::Cause gc_cause) {
3723 assert_heap_not_locked_and_not_at_safepoint();
3724 g1_policy()->record_stop_world_start();
3725 VM_G1IncCollectionPause op(gc_count_before,
3726 word_size,
3727 false, /* should_initiate_conc_mark */
3728 g1_policy()->max_pause_time_ms(),
3729 gc_cause);
3730 VMThread::execute(&op);
3731
3732 HeapWord* result = op.result();
3733 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3734 assert(result == NULL || ret_succeeded,
3735 "the result should be NULL if the VM did not succeed");
3736 *succeeded = ret_succeeded;
3737
3738 assert_heap_not_locked();
3739 return result;
3740 }
3741
3742 void
3743 G1CollectedHeap::doConcurrentMark() {
3744 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3745 if (!_cmThread->in_progress()) {
3746 _cmThread->set_started();
3747 CGC_lock->notify();
3748 }
3749 }
3750
3751 size_t G1CollectedHeap::pending_card_num() {
3752 size_t extra_cards = 0;
3753 JavaThread *curr = Threads::first();
3754 while (curr != NULL) {
3755 DirtyCardQueue& dcq = curr->dirty_card_queue();
3756 extra_cards += dcq.size();
3757 curr = curr->next();
3758 }
3759 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3760 size_t buffer_size = dcqs.buffer_size();
3761 size_t buffer_num = dcqs.completed_buffers_num();
3762
3763 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3764 // in bytes - not the number of 'entries'. We need to convert
3765 // into a number of cards.
3766 return (buffer_size * buffer_num + extra_cards) / oopSize;
3767 }
3768
3769 size_t G1CollectedHeap::cards_scanned() {
3770 return g1_rem_set()->cardsScanned();
3771 }
3772
3773 void
3774 G1CollectedHeap::setup_surviving_young_words() {
3775 assert(_surviving_young_words == NULL, "pre-condition");
3776 uint array_length = g1_policy()->young_cset_region_length();
3777 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3778 if (_surviving_young_words == NULL) {
3779 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3780 "Not enough space for young surv words summary.");
3781 }
3782 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3783 #ifdef ASSERT
3784 for (uint i = 0; i < array_length; ++i) {
3785 assert( _surviving_young_words[i] == 0, "memset above" );
3786 }
3787 #endif // !ASSERT
3788 }
3789
3790 void
3791 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3792 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3793 uint array_length = g1_policy()->young_cset_region_length();
3794 for (uint i = 0; i < array_length; ++i) {
3795 _surviving_young_words[i] += surv_young_words[i];
3796 }
3797 }
3798
3799 void
3800 G1CollectedHeap::cleanup_surviving_young_words() {
3801 guarantee( _surviving_young_words != NULL, "pre-condition" );
3802 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3803 _surviving_young_words = NULL;
3804 }
3805
3806 #ifdef ASSERT
3807 class VerifyCSetClosure: public HeapRegionClosure {
3808 public:
3809 bool doHeapRegion(HeapRegion* hr) {
3810 // Here we check that the CSet region's RSet is ready for parallel
3811 // iteration. The fields that we'll verify are only manipulated
3812 // when the region is part of a CSet and is collected. Afterwards,
3813 // we reset these fields when we clear the region's RSet (when the
3814 // region is freed) so they are ready when the region is
3815 // re-allocated. The only exception to this is if there's an
3816 // evacuation failure and instead of freeing the region we leave
3817 // it in the heap. In that case, we reset these fields during
3818 // evacuation failure handling.
3819 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3820
3821 // Here's a good place to add any other checks we'd like to
3822 // perform on CSet regions.
3823 return false;
3824 }
3825 };
3826 #endif // ASSERT
3827
3828 #if TASKQUEUE_STATS
3829 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3830 st->print_raw_cr("GC Task Stats");
3831 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3832 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3833 }
3834
3835 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3836 print_taskqueue_stats_hdr(st);
3837
3838 TaskQueueStats totals;
3839 const int n = workers() != NULL ? workers()->total_workers() : 1;
3840 for (int i = 0; i < n; ++i) {
3841 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3842 totals += task_queue(i)->stats;
3843 }
3844 st->print_raw("tot "); totals.print(st); st->cr();
3845
3846 DEBUG_ONLY(totals.verify());
3847 }
3848
3849 void G1CollectedHeap::reset_taskqueue_stats() {
3850 const int n = workers() != NULL ? workers()->total_workers() : 1;
3851 for (int i = 0; i < n; ++i) {
3852 task_queue(i)->stats.reset();
3853 }
3854 }
3855 #endif // TASKQUEUE_STATS
3856
3857 void G1CollectedHeap::log_gc_header() {
3858 if (!G1Log::fine()) {
3859 return;
3860 }
3861
3862 gclog_or_tty->date_stamp(PrintGCDateStamps);
3863 gclog_or_tty->stamp(PrintGCTimeStamps);
3864
3865 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3866 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3867 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3868
3869 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3870 }
3871
3872 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3873 if (!G1Log::fine()) {
3874 return;
3875 }
3876
3877 if (G1Log::finer()) {
3878 if (evacuation_failed()) {
3879 gclog_or_tty->print(" (to-space exhausted)");
3880 }
3881 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3882 g1_policy()->phase_times()->note_gc_end();
3883 g1_policy()->phase_times()->print(pause_time_sec);
3884 g1_policy()->print_detailed_heap_transition();
3885 } else {
3886 if (evacuation_failed()) {
3887 gclog_or_tty->print("--");
3888 }
3889 g1_policy()->print_heap_transition();
3890 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3891 }
3892 gclog_or_tty->flush();
3893 }
3894
3895 bool
3896 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3897 assert_at_safepoint(true /* should_be_vm_thread */);
3898 guarantee(!is_gc_active(), "collection is not reentrant");
3899
3900 if (GC_locker::check_active_before_gc()) {
3901 return false;
3902 }
3903
3904 _gc_timer_stw->register_gc_start();
3905
3906 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3907
3908 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3909 ResourceMark rm;
3910
3911 print_heap_before_gc();
3912 trace_heap_before_gc(_gc_tracer_stw);
3913
3914 verify_region_sets_optional();
3915 verify_dirty_young_regions();
3916
3917 // This call will decide whether this pause is an initial-mark
3918 // pause. If it is, during_initial_mark_pause() will return true
3919 // for the duration of this pause.
3920 g1_policy()->decide_on_conc_mark_initiation();
3921
3922 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3923 assert(!g1_policy()->during_initial_mark_pause() ||
3924 g1_policy()->gcs_are_young(), "sanity");
3925
3926 // We also do not allow mixed GCs during marking.
3927 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3928
3929 // Record whether this pause is an initial mark. When the current
3930 // thread has completed its logging output and it's safe to signal
3931 // the CM thread, the flag's value in the policy has been reset.
3932 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3933
3934 // Inner scope for scope based logging, timers, and stats collection
3935 {
3936 EvacuationInfo evacuation_info;
3937
3938 if (g1_policy()->during_initial_mark_pause()) {
3939 // We are about to start a marking cycle, so we increment the
3940 // full collection counter.
3941 increment_old_marking_cycles_started();
3942 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3943 }
3944
3945 _gc_tracer_stw->report_yc_type(yc_type());
3946
3947 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3948
3949 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3950 workers()->active_workers() : 1);
3951 double pause_start_sec = os::elapsedTime();
3952 g1_policy()->phase_times()->note_gc_start(active_workers);
3953 log_gc_header();
3954
3955 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3956 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3957
3958 // If the secondary_free_list is not empty, append it to the
3959 // free_list. No need to wait for the cleanup operation to finish;
3960 // the region allocation code will check the secondary_free_list
3961 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3962 // set, skip this step so that the region allocation code has to
3963 // get entries from the secondary_free_list.
3964 if (!G1StressConcRegionFreeing) {
3965 append_secondary_free_list_if_not_empty_with_lock();
3966 }
3967
3968 assert(check_young_list_well_formed(), "young list should be well formed");
3969 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3970 "sanity check");
3971
3972 // Don't dynamically change the number of GC threads this early. A value of
3973 // 0 is used to indicate serial work. When parallel work is done,
3974 // it will be set.
3975
3976 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3977 IsGCActiveMark x;
3978
3979 gc_prologue(false);
3980 increment_total_collections(false /* full gc */);
3981 increment_gc_time_stamp();
3982
3983 verify_before_gc();
3984
3985 COMPILER2_PRESENT(DerivedPointerTable::clear());
3986
3987 // Please see comment in g1CollectedHeap.hpp and
3988 // G1CollectedHeap::ref_processing_init() to see how
3989 // reference processing currently works in G1.
3990
3991 // Enable discovery in the STW reference processor
3992 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3993 true /*verify_no_refs*/);
3994
3995 {
3996 // We want to temporarily turn off discovery by the
3997 // CM ref processor, if necessary, and turn it back on
3998 // on again later if we do. Using a scoped
3999 // NoRefDiscovery object will do this.
4000 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4001
4002 // Forget the current alloc region (we might even choose it to be part
4003 // of the collection set!).
4004 release_mutator_alloc_region();
4005
4006 // We should call this after we retire the mutator alloc
4007 // region(s) so that all the ALLOC / RETIRE events are generated
4008 // before the start GC event.
4009 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4010
4011 // This timing is only used by the ergonomics to handle our pause target.
4012 // It is unclear why this should not include the full pause. We will
4013 // investigate this in CR 7178365.
4014 //
4015 // Preserving the old comment here if that helps the investigation:
4016 //
4017 // The elapsed time induced by the start time below deliberately elides
4018 // the possible verification above.
4019 double sample_start_time_sec = os::elapsedTime();
4020
4021 #if YOUNG_LIST_VERBOSE
4022 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4023 _young_list->print();
4024 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4025 #endif // YOUNG_LIST_VERBOSE
4026
4027 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4028
4029 double scan_wait_start = os::elapsedTime();
4030 // We have to wait until the CM threads finish scanning the
4031 // root regions as it's the only way to ensure that all the
4032 // objects on them have been correctly scanned before we start
4033 // moving them during the GC.
4034 bool waited = _cm->root_regions()->wait_until_scan_finished();
4035 double wait_time_ms = 0.0;
4036 if (waited) {
4037 double scan_wait_end = os::elapsedTime();
4038 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4039 }
4040 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4041
4042 #if YOUNG_LIST_VERBOSE
4043 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4044 _young_list->print();
4045 #endif // YOUNG_LIST_VERBOSE
4046
4047 if (g1_policy()->during_initial_mark_pause()) {
4048 concurrent_mark()->checkpointRootsInitialPre();
4049 }
4050
4051 #if YOUNG_LIST_VERBOSE
4052 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4053 _young_list->print();
4054 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4055 #endif // YOUNG_LIST_VERBOSE
4056
4057 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4058
4059 _cm->note_start_of_gc();
4060 // We should not verify the per-thread SATB buffers given that
4061 // we have not filtered them yet (we'll do so during the
4062 // GC). We also call this after finalize_cset() to
4063 // ensure that the CSet has been finalized.
4064 _cm->verify_no_cset_oops(true /* verify_stacks */,
4065 true /* verify_enqueued_buffers */,
4066 false /* verify_thread_buffers */,
4067 true /* verify_fingers */);
4068
4069 if (_hr_printer.is_active()) {
4070 HeapRegion* hr = g1_policy()->collection_set();
4071 while (hr != NULL) {
4072 G1HRPrinter::RegionType type;
4073 if (!hr->is_young()) {
4074 type = G1HRPrinter::Old;
4075 } else if (hr->is_survivor()) {
4076 type = G1HRPrinter::Survivor;
4077 } else {
4078 type = G1HRPrinter::Eden;
4079 }
4080 _hr_printer.cset(hr);
4081 hr = hr->next_in_collection_set();
4082 }
4083 }
4084
4085 #ifdef ASSERT
4086 VerifyCSetClosure cl;
4087 collection_set_iterate(&cl);
4088 #endif // ASSERT
4089
4090 setup_surviving_young_words();
4091
4092 // Initialize the GC alloc regions.
4093 init_gc_alloc_regions(evacuation_info);
4094
4095 // Actually do the work...
4096 evacuate_collection_set(evacuation_info);
4097
4098 // We do this to mainly verify the per-thread SATB buffers
4099 // (which have been filtered by now) since we didn't verify
4100 // them earlier. No point in re-checking the stacks / enqueued
4101 // buffers given that the CSet has not changed since last time
4102 // we checked.
4103 _cm->verify_no_cset_oops(false /* verify_stacks */,
4104 false /* verify_enqueued_buffers */,
4105 true /* verify_thread_buffers */,
4106 true /* verify_fingers */);
4107
4108 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4109 g1_policy()->clear_collection_set();
4110
4111 cleanup_surviving_young_words();
4112
4113 // Start a new incremental collection set for the next pause.
4114 g1_policy()->start_incremental_cset_building();
4115
4116 clear_cset_fast_test();
4117
4118 _young_list->reset_sampled_info();
4119
4120 // Don't check the whole heap at this point as the
4121 // GC alloc regions from this pause have been tagged
4122 // as survivors and moved on to the survivor list.
4123 // Survivor regions will fail the !is_young() check.
4124 assert(check_young_list_empty(false /* check_heap */),
4125 "young list should be empty");
4126
4127 #if YOUNG_LIST_VERBOSE
4128 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4129 _young_list->print();
4130 #endif // YOUNG_LIST_VERBOSE
4131
4132 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4133 _young_list->first_survivor_region(),
4134 _young_list->last_survivor_region());
4135
4136 _young_list->reset_auxilary_lists();
4137
4138 if (evacuation_failed()) {
4139 _summary_bytes_used = recalculate_used();
4140 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4141 for (uint i = 0; i < n_queues; i++) {
4142 if (_evacuation_failed_info_array[i].has_failed()) {
4143 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4144 }
4145 }
4146 } else {
4147 // The "used" of the the collection set have already been subtracted
4148 // when they were freed. Add in the bytes evacuated.
4149 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4150 }
4151
4152 if (g1_policy()->during_initial_mark_pause()) {
4153 // We have to do this before we notify the CM threads that
4154 // they can start working to make sure that all the
4155 // appropriate initialization is done on the CM object.
4156 concurrent_mark()->checkpointRootsInitialPost();
4157 set_marking_started();
4158 // Note that we don't actually trigger the CM thread at
4159 // this point. We do that later when we're sure that
4160 // the current thread has completed its logging output.
4161 }
4162
4163 allocate_dummy_regions();
4164
4165 #if YOUNG_LIST_VERBOSE
4166 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4167 _young_list->print();
4168 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4169 #endif // YOUNG_LIST_VERBOSE
4170
4171 init_mutator_alloc_region();
4172
4173 {
4174 size_t expand_bytes = g1_policy()->expansion_amount();
4175 if (expand_bytes > 0) {
4176 size_t bytes_before = capacity();
4177 // No need for an ergo verbose message here,
4178 // expansion_amount() does this when it returns a value > 0.
4179 if (!expand(expand_bytes)) {
4180 // We failed to expand the heap so let's verify that
4181 // committed/uncommitted amount match the backing store
4182 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4183 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4184 }
4185 }
4186 }
4187
4188 // We redo the verification but now wrt to the new CSet which
4189 // has just got initialized after the previous CSet was freed.
4190 _cm->verify_no_cset_oops(true /* verify_stacks */,
4191 true /* verify_enqueued_buffers */,
4192 true /* verify_thread_buffers */,
4193 true /* verify_fingers */);
4194 _cm->note_end_of_gc();
4195
4196 // This timing is only used by the ergonomics to handle our pause target.
4197 // It is unclear why this should not include the full pause. We will
4198 // investigate this in CR 7178365.
4199 double sample_end_time_sec = os::elapsedTime();
4200 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4201 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4202
4203 MemoryService::track_memory_usage();
4204
4205 // In prepare_for_verify() below we'll need to scan the deferred
4206 // update buffers to bring the RSets up-to-date if
4207 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4208 // the update buffers we'll probably need to scan cards on the
4209 // regions we just allocated to (i.e., the GC alloc
4210 // regions). However, during the last GC we called
4211 // set_saved_mark() on all the GC alloc regions, so card
4212 // scanning might skip the [saved_mark_word()...top()] area of
4213 // those regions (i.e., the area we allocated objects into
4214 // during the last GC). But it shouldn't. Given that
4215 // saved_mark_word() is conditional on whether the GC time stamp
4216 // on the region is current or not, by incrementing the GC time
4217 // stamp here we invalidate all the GC time stamps on all the
4218 // regions and saved_mark_word() will simply return top() for
4219 // all the regions. This is a nicer way of ensuring this rather
4220 // than iterating over the regions and fixing them. In fact, the
4221 // GC time stamp increment here also ensures that
4222 // saved_mark_word() will return top() between pauses, i.e.,
4223 // during concurrent refinement. So we don't need the
4224 // is_gc_active() check to decided which top to use when
4225 // scanning cards (see CR 7039627).
4226 increment_gc_time_stamp();
4227
4228 verify_after_gc();
4229
4230 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4231 ref_processor_stw()->verify_no_references_recorded();
4232
4233 // CM reference discovery will be re-enabled if necessary.
4234 }
4235
4236 // We should do this after we potentially expand the heap so
4237 // that all the COMMIT events are generated before the end GC
4238 // event, and after we retire the GC alloc regions so that all
4239 // RETIRE events are generated before the end GC event.
4240 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4241
4242 if (mark_in_progress()) {
4243 concurrent_mark()->update_g1_committed();
4244 }
4245
4246 #ifdef TRACESPINNING
4247 ParallelTaskTerminator::print_termination_counts();
4248 #endif
4249
4250 gc_epilogue(false);
4251 }
4252
4253 // Print the remainder of the GC log output.
4254 log_gc_footer(os::elapsedTime() - pause_start_sec);
4255
4256 // It is not yet to safe to tell the concurrent mark to
4257 // start as we have some optional output below. We don't want the
4258 // output from the concurrent mark thread interfering with this
4259 // logging output either.
4260
4261 _hrs.verify_optional();
4262 verify_region_sets_optional();
4263
4264 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4265 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4266
4267 print_heap_after_gc();
4268 trace_heap_after_gc(_gc_tracer_stw);
4269
4270 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4271 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4272 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4273 // before any GC notifications are raised.
4274 g1mm()->update_sizes();
4275
4276 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4277 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4278 _gc_timer_stw->register_gc_end();
4279 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4280 }
4281 // It should now be safe to tell the concurrent mark thread to start
4282 // without its logging output interfering with the logging output
4283 // that came from the pause.
4284
4285 if (should_start_conc_mark) {
4286 // CAUTION: after the doConcurrentMark() call below,
4287 // the concurrent marking thread(s) could be running
4288 // concurrently with us. Make sure that anything after
4289 // this point does not assume that we are the only GC thread
4290 // running. Note: of course, the actual marking work will
4291 // not start until the safepoint itself is released in
4292 // SuspendibleThreadSet::desynchronize().
4293 doConcurrentMark();
4294 }
4295
4296 return true;
4297 }
4298
4299 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4300 {
4301 size_t gclab_word_size;
4302 switch (purpose) {
4303 case GCAllocForSurvived:
4304 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4305 break;
4306 case GCAllocForTenured:
4307 gclab_word_size = _old_plab_stats.desired_plab_sz();
4308 break;
4309 default:
4310 assert(false, "unknown GCAllocPurpose");
4311 gclab_word_size = _old_plab_stats.desired_plab_sz();
4312 break;
4313 }
4314
4315 // Prevent humongous PLAB sizes for two reasons:
4316 // * PLABs are allocated using a similar paths as oops, but should
4317 // never be in a humongous region
4318 // * Allowing humongous PLABs needlessly churns the region free lists
4319 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4320 }
4321
4322 void G1CollectedHeap::init_mutator_alloc_region() {
4323 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4324 _mutator_alloc_region.init();
4325 }
4326
4327 void G1CollectedHeap::release_mutator_alloc_region() {
4328 _mutator_alloc_region.release();
4329 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4330 }
4331
4332 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4333 assert_at_safepoint(true /* should_be_vm_thread */);
4334
4335 _survivor_gc_alloc_region.init();
4336 _old_gc_alloc_region.init();
4337 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4338 _retained_old_gc_alloc_region = NULL;
4339
4340 // We will discard the current GC alloc region if:
4341 // a) it's in the collection set (it can happen!),
4342 // b) it's already full (no point in using it),
4343 // c) it's empty (this means that it was emptied during
4344 // a cleanup and it should be on the free list now), or
4345 // d) it's humongous (this means that it was emptied
4346 // during a cleanup and was added to the free list, but
4347 // has been subsequently used to allocate a humongous
4348 // object that may be less than the region size).
4349 if (retained_region != NULL &&
4350 !retained_region->in_collection_set() &&
4351 !(retained_region->top() == retained_region->end()) &&
4352 !retained_region->is_empty() &&
4353 !retained_region->isHumongous()) {
4354 retained_region->set_saved_mark();
4355 // The retained region was added to the old region set when it was
4356 // retired. We have to remove it now, since we don't allow regions
4357 // we allocate to in the region sets. We'll re-add it later, when
4358 // it's retired again.
4359 _old_set.remove(retained_region);
4360 bool during_im = g1_policy()->during_initial_mark_pause();
4361 retained_region->note_start_of_copying(during_im);
4362 _old_gc_alloc_region.set(retained_region);
4363 _hr_printer.reuse(retained_region);
4364 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4365 }
4366 }
4367
4368 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4369 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4370 _old_gc_alloc_region.count());
4371 _survivor_gc_alloc_region.release();
4372 // If we have an old GC alloc region to release, we'll save it in
4373 // _retained_old_gc_alloc_region. If we don't
4374 // _retained_old_gc_alloc_region will become NULL. This is what we
4375 // want either way so no reason to check explicitly for either
4376 // condition.
4377 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4378
4379 if (ResizePLAB) {
4380 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4381 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4382 }
4383 }
4384
4385 void G1CollectedHeap::abandon_gc_alloc_regions() {
4386 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4387 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4388 _retained_old_gc_alloc_region = NULL;
4389 }
4390
4391 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4392 _drain_in_progress = false;
4393 set_evac_failure_closure(cl);
4394 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4395 }
4396
4397 void G1CollectedHeap::finalize_for_evac_failure() {
4398 assert(_evac_failure_scan_stack != NULL &&
4399 _evac_failure_scan_stack->length() == 0,
4400 "Postcondition");
4401 assert(!_drain_in_progress, "Postcondition");
4402 delete _evac_failure_scan_stack;
4403 _evac_failure_scan_stack = NULL;
4404 }
4405
4406 void G1CollectedHeap::remove_self_forwarding_pointers() {
4407 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4408
4409 double remove_self_forwards_start = os::elapsedTime();
4410
4411 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4412
4413 if (G1CollectedHeap::use_parallel_gc_threads()) {
4414 set_par_threads();
4415 workers()->run_task(&rsfp_task);
4416 set_par_threads(0);
4417 } else {
4418 rsfp_task.work(0);
4419 }
4420
4421 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4422
4423 // Reset the claim values in the regions in the collection set.
4424 reset_cset_heap_region_claim_values();
4425
4426 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4427
4428 // Now restore saved marks, if any.
4429 assert(_objs_with_preserved_marks.size() ==
4430 _preserved_marks_of_objs.size(), "Both or none.");
4431 while (!_objs_with_preserved_marks.is_empty()) {
4432 oop obj = _objs_with_preserved_marks.pop();
4433 markOop m = _preserved_marks_of_objs.pop();
4434 obj->set_mark(m);
4435 }
4436 _objs_with_preserved_marks.clear(true);
4437 _preserved_marks_of_objs.clear(true);
4438
4439 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4440 }
4441
4442 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4443 _evac_failure_scan_stack->push(obj);
4444 }
4445
4446 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4447 assert(_evac_failure_scan_stack != NULL, "precondition");
4448
4449 while (_evac_failure_scan_stack->length() > 0) {
4450 oop obj = _evac_failure_scan_stack->pop();
4451 _evac_failure_closure->set_region(heap_region_containing(obj));
4452 obj->oop_iterate_backwards(_evac_failure_closure);
4453 }
4454 }
4455
4456 oop
4457 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4458 oop old) {
4459 assert(obj_in_cs(old),
4460 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4461 (HeapWord*) old));
4462 markOop m = old->mark();
4463 oop forward_ptr = old->forward_to_atomic(old);
4464 if (forward_ptr == NULL) {
4465 // Forward-to-self succeeded.
4466 assert(_par_scan_state != NULL, "par scan state");
4467 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4468 uint queue_num = _par_scan_state->queue_num();
4469
4470 _evacuation_failed = true;
4471 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4472 if (_evac_failure_closure != cl) {
4473 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4474 assert(!_drain_in_progress,
4475 "Should only be true while someone holds the lock.");
4476 // Set the global evac-failure closure to the current thread's.
4477 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4478 set_evac_failure_closure(cl);
4479 // Now do the common part.
4480 handle_evacuation_failure_common(old, m);
4481 // Reset to NULL.
4482 set_evac_failure_closure(NULL);
4483 } else {
4484 // The lock is already held, and this is recursive.
4485 assert(_drain_in_progress, "This should only be the recursive case.");
4486 handle_evacuation_failure_common(old, m);
4487 }
4488 return old;
4489 } else {
4490 // Forward-to-self failed. Either someone else managed to allocate
4491 // space for this object (old != forward_ptr) or they beat us in
4492 // self-forwarding it (old == forward_ptr).
4493 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4494 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4495 "should not be in the CSet",
4496 (HeapWord*) old, (HeapWord*) forward_ptr));
4497 return forward_ptr;
4498 }
4499 }
4500
4501 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4502 preserve_mark_if_necessary(old, m);
4503
4504 HeapRegion* r = heap_region_containing(old);
4505 if (!r->evacuation_failed()) {
4506 r->set_evacuation_failed(true);
4507 _hr_printer.evac_failure(r);
4508 }
4509
4510 push_on_evac_failure_scan_stack(old);
4511
4512 if (!_drain_in_progress) {
4513 // prevent recursion in copy_to_survivor_space()
4514 _drain_in_progress = true;
4515 drain_evac_failure_scan_stack();
4516 _drain_in_progress = false;
4517 }
4518 }
4519
4520 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4521 assert(evacuation_failed(), "Oversaving!");
4522 // We want to call the "for_promotion_failure" version only in the
4523 // case of a promotion failure.
4524 if (m->must_be_preserved_for_promotion_failure(obj)) {
4525 _objs_with_preserved_marks.push(obj);
4526 _preserved_marks_of_objs.push(m);
4527 }
4528 }
4529
4530 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4531 size_t word_size) {
4532 if (purpose == GCAllocForSurvived) {
4533 HeapWord* result = survivor_attempt_allocation(word_size);
4534 if (result != NULL) {
4535 return result;
4536 } else {
4537 // Let's try to allocate in the old gen in case we can fit the
4538 // object there.
4539 return old_attempt_allocation(word_size);
4540 }
4541 } else {
4542 assert(purpose == GCAllocForTenured, "sanity");
4543 HeapWord* result = old_attempt_allocation(word_size);
4544 if (result != NULL) {
4545 return result;
4546 } else {
4547 // Let's try to allocate in the survivors in case we can fit the
4548 // object there.
4549 return survivor_attempt_allocation(word_size);
4550 }
4551 }
4552
4553 ShouldNotReachHere();
4554 // Trying to keep some compilers happy.
4555 return NULL;
4556 }
4557
4558 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4559 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4560
4561 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4562 : _g1h(g1h),
4563 _refs(g1h->task_queue(queue_num)),
4564 _dcq(&g1h->dirty_card_queue_set()),
4565 _ct_bs(g1h->g1_barrier_set()),
4566 _g1_rem(g1h->g1_rem_set()),
4567 _hash_seed(17), _queue_num(queue_num),
4568 _term_attempts(0),
4569 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4570 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4571 _age_table(false), _scanner(g1h, this, rp),
4572 _strong_roots_time(0), _term_time(0),
4573 _alloc_buffer_waste(0), _undo_waste(0) {
4574 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4575 // we "sacrifice" entry 0 to keep track of surviving bytes for
4576 // non-young regions (where the age is -1)
4577 // We also add a few elements at the beginning and at the end in
4578 // an attempt to eliminate cache contention
4579 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4580 uint array_length = PADDING_ELEM_NUM +
4581 real_length +
4582 PADDING_ELEM_NUM;
4583 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4584 if (_surviving_young_words_base == NULL)
4585 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4586 "Not enough space for young surv histo.");
4587 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4588 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4589
4590 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4591 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4592
4593 _start = os::elapsedTime();
4594 }
4595
4596 void
4597 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4598 {
4599 st->print_raw_cr("GC Termination Stats");
4600 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4601 " ------waste (KiB)------");
4602 st->print_raw_cr("thr ms ms % ms % attempts"
4603 " total alloc undo");
4604 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4605 " ------- ------- -------");
4606 }
4607
4608 void
4609 G1ParScanThreadState::print_termination_stats(int i,
4610 outputStream* const st) const
4611 {
4612 const double elapsed_ms = elapsed_time() * 1000.0;
4613 const double s_roots_ms = strong_roots_time() * 1000.0;
4614 const double term_ms = term_time() * 1000.0;
4615 st->print_cr("%3d %9.2f %9.2f %6.2f "
4616 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4617 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4618 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4619 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4620 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4621 alloc_buffer_waste() * HeapWordSize / K,
4622 undo_waste() * HeapWordSize / K);
4623 }
4624
4625 #ifdef ASSERT
4626 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4627 assert(ref != NULL, "invariant");
4628 assert(UseCompressedOops, "sanity");
4629 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4630 oop p = oopDesc::load_decode_heap_oop(ref);
4631 assert(_g1h->is_in_g1_reserved(p),
4632 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4633 return true;
4634 }
4635
4636 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4637 assert(ref != NULL, "invariant");
4638 if (has_partial_array_mask(ref)) {
4639 // Must be in the collection set--it's already been copied.
4640 oop p = clear_partial_array_mask(ref);
4641 assert(_g1h->obj_in_cs(p),
4642 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4643 } else {
4644 oop p = oopDesc::load_decode_heap_oop(ref);
4645 assert(_g1h->is_in_g1_reserved(p),
4646 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4647 }
4648 return true;
4649 }
4650
4651 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4652 if (ref.is_narrow()) {
4653 return verify_ref((narrowOop*) ref);
4654 } else {
4655 return verify_ref((oop*) ref);
4656 }
4657 }
4658 #endif // ASSERT
4659
4660 void G1ParScanThreadState::trim_queue() {
4661 assert(_evac_failure_cl != NULL, "not set");
4662
4663 StarTask ref;
4664 do {
4665 // Drain the overflow stack first, so other threads can steal.
4666 while (refs()->pop_overflow(ref)) {
4667 deal_with_reference(ref);
4668 }
4669
4670 while (refs()->pop_local(ref)) {
4671 deal_with_reference(ref);
4672 }
4673 } while (!refs()->is_empty());
4674 }
4675
4676 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4677 G1ParScanThreadState* par_scan_state) :
4678 _g1(g1), _par_scan_state(par_scan_state),
4679 _worker_id(par_scan_state->queue_num()) { }
4680
4681 void G1ParCopyHelper::mark_object(oop obj) {
4682 #ifdef ASSERT
4683 HeapRegion* hr = _g1->heap_region_containing(obj);
4684 assert(hr != NULL, "sanity");
4685 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4686 #endif // ASSERT
4687
4688 // We know that the object is not moving so it's safe to read its size.
4689 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4690 }
4691
4692 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4693 #ifdef ASSERT
4694 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4695 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4696 assert(from_obj != to_obj, "should not be self-forwarded");
4697
4698 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4699 assert(from_hr != NULL, "sanity");
4700 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4701
4702 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4703 assert(to_hr != NULL, "sanity");
4704 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4705 #endif // ASSERT
4706
4707 // The object might be in the process of being copied by another
4708 // worker so we cannot trust that its to-space image is
4709 // well-formed. So we have to read its size from its from-space
4710 // image which we know should not be changing.
4711 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4712 }
4713
4714 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4715 size_t word_sz = old->size();
4716 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4717 // +1 to make the -1 indexes valid...
4718 int young_index = from_region->young_index_in_cset()+1;
4719 assert( (from_region->is_young() && young_index > 0) ||
4720 (!from_region->is_young() && young_index == 0), "invariant" );
4721 G1CollectorPolicy* g1p = _g1h->g1_policy();
4722 markOop m = old->mark();
4723 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4724 : m->age();
4725 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4726 word_sz);
4727 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4728 #ifndef PRODUCT
4729 // Should this evacuation fail?
4730 if (_g1h->evacuation_should_fail()) {
4731 if (obj_ptr != NULL) {
4732 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4733 obj_ptr = NULL;
4734 }
4735 }
4736 #endif // !PRODUCT
4737
4738 if (obj_ptr == NULL) {
4739 // This will either forward-to-self, or detect that someone else has
4740 // installed a forwarding pointer.
4741 return _g1h->handle_evacuation_failure_par(this, old);
4742 }
4743
4744 oop obj = oop(obj_ptr);
4745
4746 // We're going to allocate linearly, so might as well prefetch ahead.
4747 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4748
4749 oop forward_ptr = old->forward_to_atomic(obj);
4750 if (forward_ptr == NULL) {
4751 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4752
4753 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4754 // we actually allocated from and update alloc_purpose accordingly
4755 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4756 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4757
4758 if (g1p->track_object_age(alloc_purpose)) {
4759 // We could simply do obj->incr_age(). However, this causes a
4760 // performance issue. obj->incr_age() will first check whether
4761 // the object has a displaced mark by checking its mark word;
4762 // getting the mark word from the new location of the object
4763 // stalls. So, given that we already have the mark word and we
4764 // are about to install it anyway, it's better to increase the
4765 // age on the mark word, when the object does not have a
4766 // displaced mark word. We're not expecting many objects to have
4767 // a displaced marked word, so that case is not optimized
4768 // further (it could be...) and we simply call obj->incr_age().
4769
4770 if (m->has_displaced_mark_helper()) {
4771 // in this case, we have to install the mark word first,
4772 // otherwise obj looks to be forwarded (the old mark word,
4773 // which contains the forward pointer, was copied)
4774 obj->set_mark(m);
4775 obj->incr_age();
4776 } else {
4777 m = m->incr_age();
4778 obj->set_mark(m);
4779 }
4780 age_table()->add(obj, word_sz);
4781 } else {
4782 obj->set_mark(m);
4783 }
4784
4785 if (G1StringDedup::is_enabled()) {
4786 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4787 to_region->is_young(),
4788 queue_num(),
4789 obj);
4790 }
4791
4792 size_t* surv_young_words = surviving_young_words();
4793 surv_young_words[young_index] += word_sz;
4794
4795 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4796 // We keep track of the next start index in the length field of
4797 // the to-space object. The actual length can be found in the
4798 // length field of the from-space object.
4799 arrayOop(obj)->set_length(0);
4800 oop* old_p = set_partial_array_mask(old);
4801 push_on_queue(old_p);
4802 } else {
4803 // No point in using the slower heap_region_containing() method,
4804 // given that we know obj is in the heap.
4805 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4806 obj->oop_iterate_backwards(&_scanner);
4807 }
4808 } else {
4809 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4810 obj = forward_ptr;
4811 }
4812 return obj;
4813 }
4814
4815 template <class T>
4816 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4817 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4818 _scanned_klass->record_modified_oops();
4819 }
4820 }
4821
4822 template <G1Barrier barrier, bool do_mark_object>
4823 template <class T>
4824 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4825 T heap_oop = oopDesc::load_heap_oop(p);
4826
4827 if (oopDesc::is_null(heap_oop)) {
4828 return;
4829 }
4830
4831 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4832
4833 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4834
4835 if (_g1->in_cset_fast_test(obj)) {
4836 oop forwardee;
4837 if (obj->is_forwarded()) {
4838 forwardee = obj->forwardee();
4839 } else {
4840 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4841 }
4842 assert(forwardee != NULL, "forwardee should not be NULL");
4843 oopDesc::encode_store_heap_oop(p, forwardee);
4844 if (do_mark_object && forwardee != obj) {
4845 // If the object is self-forwarded we don't need to explicitly
4846 // mark it, the evacuation failure protocol will do so.
4847 mark_forwarded_object(obj, forwardee);
4848 }
4849
4850 if (barrier == G1BarrierKlass) {
4851 do_klass_barrier(p, forwardee);
4852 }
4853 } else {
4854 // The object is not in collection set. If we're a root scanning
4855 // closure during an initial mark pause (i.e. do_mark_object will
4856 // be true) then attempt to mark the object.
4857 if (do_mark_object) {
4858 mark_object(obj);
4859 }
4860 }
4861
4862 if (barrier == G1BarrierEvac) {
4863 _par_scan_state->update_rs(_from, p, _worker_id);
4864 }
4865 }
4866
4867 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4868 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4869
4870 class G1ParEvacuateFollowersClosure : public VoidClosure {
4871 protected:
4872 G1CollectedHeap* _g1h;
4873 G1ParScanThreadState* _par_scan_state;
4874 RefToScanQueueSet* _queues;
4875 ParallelTaskTerminator* _terminator;
4876
4877 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4878 RefToScanQueueSet* queues() { return _queues; }
4879 ParallelTaskTerminator* terminator() { return _terminator; }
4880
4881 public:
4882 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4883 G1ParScanThreadState* par_scan_state,
4884 RefToScanQueueSet* queues,
4885 ParallelTaskTerminator* terminator)
4886 : _g1h(g1h), _par_scan_state(par_scan_state),
4887 _queues(queues), _terminator(terminator) {}
4888
4889 void do_void();
4890
4891 private:
4892 inline bool offer_termination();
4893 };
4894
4895 bool G1ParEvacuateFollowersClosure::offer_termination() {
4896 G1ParScanThreadState* const pss = par_scan_state();
4897 pss->start_term_time();
4898 const bool res = terminator()->offer_termination();
4899 pss->end_term_time();
4900 return res;
4901 }
4902
4903 void G1ParEvacuateFollowersClosure::do_void() {
4904 StarTask stolen_task;
4905 G1ParScanThreadState* const pss = par_scan_state();
4906 pss->trim_queue();
4907
4908 do {
4909 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4910 assert(pss->verify_task(stolen_task), "sanity");
4911 if (stolen_task.is_narrow()) {
4912 pss->deal_with_reference((narrowOop*) stolen_task);
4913 } else {
4914 pss->deal_with_reference((oop*) stolen_task);
4915 }
4916
4917 // We've just processed a reference and we might have made
4918 // available new entries on the queues. So we have to make sure
4919 // we drain the queues as necessary.
4920 pss->trim_queue();
4921 }
4922 } while (!offer_termination());
4923 }
4924
4925 class G1KlassScanClosure : public KlassClosure {
4926 G1ParCopyHelper* _closure;
4927 bool _process_only_dirty;
4928 int _count;
4929 public:
4930 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4931 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4932 void do_klass(Klass* klass) {
4933 // If the klass has not been dirtied we know that there's
4934 // no references into the young gen and we can skip it.
4935 if (!_process_only_dirty || klass->has_modified_oops()) {
4936 // Clean the klass since we're going to scavenge all the metadata.
4937 klass->clear_modified_oops();
4938
4939 // Tell the closure that this klass is the Klass to scavenge
4940 // and is the one to dirty if oops are left pointing into the young gen.
4941 _closure->set_scanned_klass(klass);
4942
4943 klass->oops_do(_closure);
4944
4945 _closure->set_scanned_klass(NULL);
4946 }
4947 _count++;
4948 }
4949 };
4950
4951 class G1ParTask : public AbstractGangTask {
4952 protected:
4953 G1CollectedHeap* _g1h;
4954 RefToScanQueueSet *_queues;
4955 ParallelTaskTerminator _terminator;
4956 uint _n_workers;
4957
4958 Mutex _stats_lock;
4959 Mutex* stats_lock() { return &_stats_lock; }
4960
4961 size_t getNCards() {
4962 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4963 / G1BlockOffsetSharedArray::N_bytes;
4964 }
4965
4966 public:
4967 G1ParTask(G1CollectedHeap* g1h,
4968 RefToScanQueueSet *task_queues)
4969 : AbstractGangTask("G1 collection"),
4970 _g1h(g1h),
4971 _queues(task_queues),
4972 _terminator(0, _queues),
4973 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4974 {}
4975
4976 RefToScanQueueSet* queues() { return _queues; }
4977
4978 RefToScanQueue *work_queue(int i) {
4979 return queues()->queue(i);
4980 }
4981
4982 ParallelTaskTerminator* terminator() { return &_terminator; }
4983
4984 virtual void set_for_termination(int active_workers) {
4985 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4986 // in the young space (_par_seq_tasks) in the G1 heap
4987 // for SequentialSubTasksDone.
4988 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4989 // both of which need setting by set_n_termination().
4990 _g1h->SharedHeap::set_n_termination(active_workers);
4991 _g1h->set_n_termination(active_workers);
4992 terminator()->reset_for_reuse(active_workers);
4993 _n_workers = active_workers;
4994 }
4995
4996 void work(uint worker_id) {
4997 if (worker_id >= _n_workers) return; // no work needed this round
4998
4999 double start_time_ms = os::elapsedTime() * 1000.0;
5000 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5001
5002 {
5003 ResourceMark rm;
5004 HandleMark hm;
5005
5006 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5007
5008 G1ParScanThreadState pss(_g1h, worker_id, rp);
5009 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5010
5011 pss.set_evac_failure_closure(&evac_failure_cl);
5012
5013 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5014 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5015
5016 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5017 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5018
5019 bool only_young = _g1h->g1_policy()->gcs_are_young();
5020 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5021 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5022
5023 OopClosure* scan_root_cl = &only_scan_root_cl;
5024 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5025
5026 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5027 // We also need to mark copied objects.
5028 scan_root_cl = &scan_mark_root_cl;
5029 scan_klasses_cl = &scan_mark_klasses_cl_s;
5030 }
5031
5032 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5033
5034 // Don't scan the scavengable methods in the code cache as part
5035 // of strong root scanning. The code roots that point into a
5036 // region in the collection set are scanned when we scan the
5037 // region's RSet.
5038 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5039
5040 pss.start_strong_roots();
5041 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5042 SharedHeap::ScanningOption(so),
5043 scan_root_cl,
5044 &push_heap_rs_cl,
5045 scan_klasses_cl,
5046 worker_id);
5047 pss.end_strong_roots();
5048
5049 {
5050 double start = os::elapsedTime();
5051 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5052 evac.do_void();
5053 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5054 double term_ms = pss.term_time()*1000.0;
5055 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5056 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5057 }
5058 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5059 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5060
5061 if (ParallelGCVerbose) {
5062 MutexLocker x(stats_lock());
5063 pss.print_termination_stats(worker_id);
5064 }
5065
5066 assert(pss.refs()->is_empty(), "should be empty");
5067
5068 // Close the inner scope so that the ResourceMark and HandleMark
5069 // destructors are executed here and are included as part of the
5070 // "GC Worker Time".
5071 }
5072
5073 double end_time_ms = os::elapsedTime() * 1000.0;
5074 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5075 }
5076 };
5077
5078 // *** Common G1 Evacuation Stuff
5079
5080 // This method is run in a GC worker.
5081
5082 void
5083 G1CollectedHeap::
5084 g1_process_strong_roots(bool is_scavenging,
5085 ScanningOption so,
5086 OopClosure* scan_non_heap_roots,
5087 OopsInHeapRegionClosure* scan_rs,
5088 G1KlassScanClosure* scan_klasses,
5089 uint worker_i) {
5090
5091 // First scan the strong roots
5092 double ext_roots_start = os::elapsedTime();
5093 double closure_app_time_sec = 0.0;
5094
5095 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5096
5097 process_strong_roots(false, // no scoping; this is parallel code
5098 so,
5099 &buf_scan_non_heap_roots,
5100 scan_klasses
5101 );
5102
5103 // Now the CM ref_processor roots.
5104 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5105 // We need to treat the discovered reference lists of the
5106 // concurrent mark ref processor as roots and keep entries
5107 // (which are added by the marking threads) on them live
5108 // until they can be processed at the end of marking.
5109 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5110 }
5111
5112 // Finish up any enqueued closure apps (attributed as object copy time).
5113 buf_scan_non_heap_roots.done();
5114
5115 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5116
5117 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5118
5119 double ext_root_time_ms =
5120 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5121
5122 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5123
5124 // During conc marking we have to filter the per-thread SATB buffers
5125 // to make sure we remove any oops into the CSet (which will show up
5126 // as implicitly live).
5127 double satb_filtering_ms = 0.0;
5128 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5129 if (mark_in_progress()) {
5130 double satb_filter_start = os::elapsedTime();
5131
5132 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5133
5134 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5135 }
5136 }
5137 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5138
5139 // If this is an initial mark pause, and we're not scanning
5140 // the entire code cache, we need to mark the oops in the
5141 // strong code root lists for the regions that are not in
5142 // the collection set.
5143 // Note all threads participate in this set of root tasks.
5144 double mark_strong_code_roots_ms = 0.0;
5145 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5146 double mark_strong_roots_start = os::elapsedTime();
5147 mark_strong_code_roots(worker_i);
5148 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5149 }
5150 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5151
5152 // Now scan the complement of the collection set.
5153 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5154 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5155
5156 _process_strong_tasks->all_tasks_completed();
5157 }
5158
5159 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5160 private:
5161 BoolObjectClosure* _is_alive;
5162 int _initial_string_table_size;
5163 int _initial_symbol_table_size;
5164
5165 bool _process_strings;
5166 int _strings_processed;
5167 int _strings_removed;
5168
5169 bool _process_symbols;
5170 int _symbols_processed;
5171 int _symbols_removed;
5172
5173 bool _do_in_parallel;
5174 public:
5175 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5176 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5177 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5178 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5179 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5180
5181 _initial_string_table_size = StringTable::the_table()->table_size();
5182 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5183 if (process_strings) {
5184 StringTable::clear_parallel_claimed_index();
5185 }
5186 if (process_symbols) {
5187 SymbolTable::clear_parallel_claimed_index();
5188 }
5189 }
5190
5191 ~G1StringSymbolTableUnlinkTask() {
5192 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5193 err_msg("claim value %d after unlink less than initial string table size %d",
5194 StringTable::parallel_claimed_index(), _initial_string_table_size));
5195 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5196 err_msg("claim value %d after unlink less than initial symbol table size %d",
5197 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5198 }
5199
5200 void work(uint worker_id) {
5201 if (_do_in_parallel) {
5202 int strings_processed = 0;
5203 int strings_removed = 0;
5204 int symbols_processed = 0;
5205 int symbols_removed = 0;
5206 if (_process_strings) {
5207 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5208 Atomic::add(strings_processed, &_strings_processed);
5209 Atomic::add(strings_removed, &_strings_removed);
5210 }
5211 if (_process_symbols) {
5212 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5213 Atomic::add(symbols_processed, &_symbols_processed);
5214 Atomic::add(symbols_removed, &_symbols_removed);
5215 }
5216 } else {
5217 if (_process_strings) {
5218 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5219 }
5220 if (_process_symbols) {
5221 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5222 }
5223 }
5224 }
5225
5226 size_t strings_processed() const { return (size_t)_strings_processed; }
5227 size_t strings_removed() const { return (size_t)_strings_removed; }
5228
5229 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5230 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5231 };
5232
5233 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5234 bool process_strings, bool process_symbols) {
5235 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5236 _g1h->workers()->active_workers() : 1);
5237
5238 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5239 if (G1CollectedHeap::use_parallel_gc_threads()) {
5240 set_par_threads(n_workers);
5241 workers()->run_task(&g1_unlink_task);
5242 set_par_threads(0);
5243 } else {
5244 g1_unlink_task.work(0);
5245 }
5246 if (G1TraceStringSymbolTableScrubbing) {
5247 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5248 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5249 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5250 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5251 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5252 }
5253
5254 if (G1StringDedup::is_enabled()) {
5255 G1StringDedup::unlink(is_alive);
5256 }
5257 }
5258
5259 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5260 private:
5261 DirtyCardQueueSet* _queue;
5262 public:
5263 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5264
5265 virtual void work(uint worker_id) {
5266 double start_time = os::elapsedTime();
5267
5268 RedirtyLoggedCardTableEntryClosure cl;
5269 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5270 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5271 } else {
5272 _queue->apply_closure_to_all_completed_buffers(&cl);
5273 }
5274
5275 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5276 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5277 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5278 }
5279 };
5280
5281 void G1CollectedHeap::redirty_logged_cards() {
5282 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5283 double redirty_logged_cards_start = os::elapsedTime();
5284
5285 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5286 _g1h->workers()->active_workers() : 1);
5287
5288 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5289 dirty_card_queue_set().reset_for_par_iteration();
5290 if (use_parallel_gc_threads()) {
5291 set_par_threads(n_workers);
5292 workers()->run_task(&redirty_task);
5293 set_par_threads(0);
5294 } else {
5295 redirty_task.work(0);
5296 }
5297
5298 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5299 dcq.merge_bufferlists(&dirty_card_queue_set());
5300 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5301
5302 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5303 }
5304
5305 // Weak Reference Processing support
5306
5307 // An always "is_alive" closure that is used to preserve referents.
5308 // If the object is non-null then it's alive. Used in the preservation
5309 // of referent objects that are pointed to by reference objects
5310 // discovered by the CM ref processor.
5311 class G1AlwaysAliveClosure: public BoolObjectClosure {
5312 G1CollectedHeap* _g1;
5313 public:
5314 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5315 bool do_object_b(oop p) {
5316 if (p != NULL) {
5317 return true;
5318 }
5319 return false;
5320 }
5321 };
5322
5323 bool G1STWIsAliveClosure::do_object_b(oop p) {
5324 // An object is reachable if it is outside the collection set,
5325 // or is inside and copied.
5326 return !_g1->obj_in_cs(p) || p->is_forwarded();
5327 }
5328
5329 // Non Copying Keep Alive closure
5330 class G1KeepAliveClosure: public OopClosure {
5331 G1CollectedHeap* _g1;
5332 public:
5333 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5334 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5335 void do_oop( oop* p) {
5336 oop obj = *p;
5337
5338 if (_g1->obj_in_cs(obj)) {
5339 assert( obj->is_forwarded(), "invariant" );
5340 *p = obj->forwardee();
5341 }
5342 }
5343 };
5344
5345 // Copying Keep Alive closure - can be called from both
5346 // serial and parallel code as long as different worker
5347 // threads utilize different G1ParScanThreadState instances
5348 // and different queues.
5349
5350 class G1CopyingKeepAliveClosure: public OopClosure {
5351 G1CollectedHeap* _g1h;
5352 OopClosure* _copy_non_heap_obj_cl;
5353 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5354 G1ParScanThreadState* _par_scan_state;
5355
5356 public:
5357 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5358 OopClosure* non_heap_obj_cl,
5359 OopsInHeapRegionClosure* metadata_obj_cl,
5360 G1ParScanThreadState* pss):
5361 _g1h(g1h),
5362 _copy_non_heap_obj_cl(non_heap_obj_cl),
5363 _copy_metadata_obj_cl(metadata_obj_cl),
5364 _par_scan_state(pss)
5365 {}
5366
5367 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5368 virtual void do_oop( oop* p) { do_oop_work(p); }
5369
5370 template <class T> void do_oop_work(T* p) {
5371 oop obj = oopDesc::load_decode_heap_oop(p);
5372
5373 if (_g1h->obj_in_cs(obj)) {
5374 // If the referent object has been forwarded (either copied
5375 // to a new location or to itself in the event of an
5376 // evacuation failure) then we need to update the reference
5377 // field and, if both reference and referent are in the G1
5378 // heap, update the RSet for the referent.
5379 //
5380 // If the referent has not been forwarded then we have to keep
5381 // it alive by policy. Therefore we have copy the referent.
5382 //
5383 // If the reference field is in the G1 heap then we can push
5384 // on the PSS queue. When the queue is drained (after each
5385 // phase of reference processing) the object and it's followers
5386 // will be copied, the reference field set to point to the
5387 // new location, and the RSet updated. Otherwise we need to
5388 // use the the non-heap or metadata closures directly to copy
5389 // the referent object and update the pointer, while avoiding
5390 // updating the RSet.
5391
5392 if (_g1h->is_in_g1_reserved(p)) {
5393 _par_scan_state->push_on_queue(p);
5394 } else {
5395 assert(!ClassLoaderDataGraph::contains((address)p),
5396 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5397 PTR_FORMAT, p));
5398 _copy_non_heap_obj_cl->do_oop(p);
5399 }
5400 }
5401 }
5402 };
5403
5404 // Serial drain queue closure. Called as the 'complete_gc'
5405 // closure for each discovered list in some of the
5406 // reference processing phases.
5407
5408 class G1STWDrainQueueClosure: public VoidClosure {
5409 protected:
5410 G1CollectedHeap* _g1h;
5411 G1ParScanThreadState* _par_scan_state;
5412
5413 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5414
5415 public:
5416 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5417 _g1h(g1h),
5418 _par_scan_state(pss)
5419 { }
5420
5421 void do_void() {
5422 G1ParScanThreadState* const pss = par_scan_state();
5423 pss->trim_queue();
5424 }
5425 };
5426
5427 // Parallel Reference Processing closures
5428
5429 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5430 // processing during G1 evacuation pauses.
5431
5432 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5433 private:
5434 G1CollectedHeap* _g1h;
5435 RefToScanQueueSet* _queues;
5436 FlexibleWorkGang* _workers;
5437 int _active_workers;
5438
5439 public:
5440 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5441 FlexibleWorkGang* workers,
5442 RefToScanQueueSet *task_queues,
5443 int n_workers) :
5444 _g1h(g1h),
5445 _queues(task_queues),
5446 _workers(workers),
5447 _active_workers(n_workers)
5448 {
5449 assert(n_workers > 0, "shouldn't call this otherwise");
5450 }
5451
5452 // Executes the given task using concurrent marking worker threads.
5453 virtual void execute(ProcessTask& task);
5454 virtual void execute(EnqueueTask& task);
5455 };
5456
5457 // Gang task for possibly parallel reference processing
5458
5459 class G1STWRefProcTaskProxy: public AbstractGangTask {
5460 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5461 ProcessTask& _proc_task;
5462 G1CollectedHeap* _g1h;
5463 RefToScanQueueSet *_task_queues;
5464 ParallelTaskTerminator* _terminator;
5465
5466 public:
5467 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5468 G1CollectedHeap* g1h,
5469 RefToScanQueueSet *task_queues,
5470 ParallelTaskTerminator* terminator) :
5471 AbstractGangTask("Process reference objects in parallel"),
5472 _proc_task(proc_task),
5473 _g1h(g1h),
5474 _task_queues(task_queues),
5475 _terminator(terminator)
5476 {}
5477
5478 virtual void work(uint worker_id) {
5479 // The reference processing task executed by a single worker.
5480 ResourceMark rm;
5481 HandleMark hm;
5482
5483 G1STWIsAliveClosure is_alive(_g1h);
5484
5485 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5486 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5487
5488 pss.set_evac_failure_closure(&evac_failure_cl);
5489
5490 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5491 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5492
5493 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5494 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5495
5496 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5497 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5498
5499 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5500 // We also need to mark copied objects.
5501 copy_non_heap_cl = ©_mark_non_heap_cl;
5502 copy_metadata_cl = ©_mark_metadata_cl;
5503 }
5504
5505 // Keep alive closure.
5506 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5507
5508 // Complete GC closure
5509 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5510
5511 // Call the reference processing task's work routine.
5512 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5513
5514 // Note we cannot assert that the refs array is empty here as not all
5515 // of the processing tasks (specifically phase2 - pp2_work) execute
5516 // the complete_gc closure (which ordinarily would drain the queue) so
5517 // the queue may not be empty.
5518 }
5519 };
5520
5521 // Driver routine for parallel reference processing.
5522 // Creates an instance of the ref processing gang
5523 // task and has the worker threads execute it.
5524 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5525 assert(_workers != NULL, "Need parallel worker threads.");
5526
5527 ParallelTaskTerminator terminator(_active_workers, _queues);
5528 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5529
5530 _g1h->set_par_threads(_active_workers);
5531 _workers->run_task(&proc_task_proxy);
5532 _g1h->set_par_threads(0);
5533 }
5534
5535 // Gang task for parallel reference enqueueing.
5536
5537 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5538 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5539 EnqueueTask& _enq_task;
5540
5541 public:
5542 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5543 AbstractGangTask("Enqueue reference objects in parallel"),
5544 _enq_task(enq_task)
5545 { }
5546
5547 virtual void work(uint worker_id) {
5548 _enq_task.work(worker_id);
5549 }
5550 };
5551
5552 // Driver routine for parallel reference enqueueing.
5553 // Creates an instance of the ref enqueueing gang
5554 // task and has the worker threads execute it.
5555
5556 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5557 assert(_workers != NULL, "Need parallel worker threads.");
5558
5559 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5560
5561 _g1h->set_par_threads(_active_workers);
5562 _workers->run_task(&enq_task_proxy);
5563 _g1h->set_par_threads(0);
5564 }
5565
5566 // End of weak reference support closures
5567
5568 // Abstract task used to preserve (i.e. copy) any referent objects
5569 // that are in the collection set and are pointed to by reference
5570 // objects discovered by the CM ref processor.
5571
5572 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5573 protected:
5574 G1CollectedHeap* _g1h;
5575 RefToScanQueueSet *_queues;
5576 ParallelTaskTerminator _terminator;
5577 uint _n_workers;
5578
5579 public:
5580 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5581 AbstractGangTask("ParPreserveCMReferents"),
5582 _g1h(g1h),
5583 _queues(task_queues),
5584 _terminator(workers, _queues),
5585 _n_workers(workers)
5586 { }
5587
5588 void work(uint worker_id) {
5589 ResourceMark rm;
5590 HandleMark hm;
5591
5592 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5593 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5594
5595 pss.set_evac_failure_closure(&evac_failure_cl);
5596
5597 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5598
5599
5600 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5601 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5602
5603 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5604 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5605
5606 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5607 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_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 copy_metadata_cl = ©_mark_metadata_cl;
5613 }
5614
5615 // Is alive closure
5616 G1AlwaysAliveClosure always_alive(_g1h);
5617
5618 // Copying keep alive closure. Applied to referent objects that need
5619 // to be copied.
5620 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5621
5622 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5623
5624 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5625 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5626
5627 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5628 // So this must be true - but assert just in case someone decides to
5629 // change the worker ids.
5630 assert(0 <= worker_id && worker_id < limit, "sanity");
5631 assert(!rp->discovery_is_atomic(), "check this code");
5632
5633 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5634 for (uint idx = worker_id; idx < limit; idx += stride) {
5635 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5636
5637 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5638 while (iter.has_next()) {
5639 // Since discovery is not atomic for the CM ref processor, we
5640 // can see some null referent objects.
5641 iter.load_ptrs(DEBUG_ONLY(true));
5642 oop ref = iter.obj();
5643
5644 // This will filter nulls.
5645 if (iter.is_referent_alive()) {
5646 iter.make_referent_alive();
5647 }
5648 iter.move_to_next();
5649 }
5650 }
5651
5652 // Drain the queue - which may cause stealing
5653 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5654 drain_queue.do_void();
5655 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5656 assert(pss.refs()->is_empty(), "should be");
5657 }
5658 };
5659
5660 // Weak Reference processing during an evacuation pause (part 1).
5661 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5662 double ref_proc_start = os::elapsedTime();
5663
5664 ReferenceProcessor* rp = _ref_processor_stw;
5665 assert(rp->discovery_enabled(), "should have been enabled");
5666
5667 // Any reference objects, in the collection set, that were 'discovered'
5668 // by the CM ref processor should have already been copied (either by
5669 // applying the external root copy closure to the discovered lists, or
5670 // by following an RSet entry).
5671 //
5672 // But some of the referents, that are in the collection set, that these
5673 // reference objects point to may not have been copied: the STW ref
5674 // processor would have seen that the reference object had already
5675 // been 'discovered' and would have skipped discovering the reference,
5676 // but would not have treated the reference object as a regular oop.
5677 // As a result the copy closure would not have been applied to the
5678 // referent object.
5679 //
5680 // We need to explicitly copy these referent objects - the references
5681 // will be processed at the end of remarking.
5682 //
5683 // We also need to do this copying before we process the reference
5684 // objects discovered by the STW ref processor in case one of these
5685 // referents points to another object which is also referenced by an
5686 // object discovered by the STW ref processor.
5687
5688 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5689 no_of_gc_workers == workers()->active_workers(),
5690 "Need to reset active GC workers");
5691
5692 set_par_threads(no_of_gc_workers);
5693 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5694 no_of_gc_workers,
5695 _task_queues);
5696
5697 if (G1CollectedHeap::use_parallel_gc_threads()) {
5698 workers()->run_task(&keep_cm_referents);
5699 } else {
5700 keep_cm_referents.work(0);
5701 }
5702
5703 set_par_threads(0);
5704
5705 // Closure to test whether a referent is alive.
5706 G1STWIsAliveClosure is_alive(this);
5707
5708 // Even when parallel reference processing is enabled, the processing
5709 // of JNI refs is serial and performed serially by the current thread
5710 // rather than by a worker. The following PSS will be used for processing
5711 // JNI refs.
5712
5713 // Use only a single queue for this PSS.
5714 G1ParScanThreadState pss(this, 0, NULL);
5715
5716 // We do not embed a reference processor in the copying/scanning
5717 // closures while we're actually processing the discovered
5718 // reference objects.
5719 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5720
5721 pss.set_evac_failure_closure(&evac_failure_cl);
5722
5723 assert(pss.refs()->is_empty(), "pre-condition");
5724
5725 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5726 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5727
5728 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5729 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5730
5731 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5732 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5733
5734 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5735 // We also need to mark copied objects.
5736 copy_non_heap_cl = ©_mark_non_heap_cl;
5737 copy_metadata_cl = ©_mark_metadata_cl;
5738 }
5739
5740 // Keep alive closure.
5741 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5742
5743 // Serial Complete GC closure
5744 G1STWDrainQueueClosure drain_queue(this, &pss);
5745
5746 // Setup the soft refs policy...
5747 rp->setup_policy(false);
5748
5749 ReferenceProcessorStats stats;
5750 if (!rp->processing_is_mt()) {
5751 // Serial reference processing...
5752 stats = rp->process_discovered_references(&is_alive,
5753 &keep_alive,
5754 &drain_queue,
5755 NULL,
5756 _gc_timer_stw);
5757 } else {
5758 // Parallel reference processing
5759 assert(rp->num_q() == no_of_gc_workers, "sanity");
5760 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5761
5762 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5763 stats = rp->process_discovered_references(&is_alive,
5764 &keep_alive,
5765 &drain_queue,
5766 &par_task_executor,
5767 _gc_timer_stw);
5768 }
5769
5770 _gc_tracer_stw->report_gc_reference_stats(stats);
5771
5772 // We have completed copying any necessary live referent objects.
5773 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5774
5775 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5776 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5777 }
5778
5779 // Weak Reference processing during an evacuation pause (part 2).
5780 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5781 double ref_enq_start = os::elapsedTime();
5782
5783 ReferenceProcessor* rp = _ref_processor_stw;
5784 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5785
5786 // Now enqueue any remaining on the discovered lists on to
5787 // the pending list.
5788 if (!rp->processing_is_mt()) {
5789 // Serial reference processing...
5790 rp->enqueue_discovered_references();
5791 } else {
5792 // Parallel reference enqueueing
5793
5794 assert(no_of_gc_workers == workers()->active_workers(),
5795 "Need to reset active workers");
5796 assert(rp->num_q() == no_of_gc_workers, "sanity");
5797 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5798
5799 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5800 rp->enqueue_discovered_references(&par_task_executor);
5801 }
5802
5803 rp->verify_no_references_recorded();
5804 assert(!rp->discovery_enabled(), "should have been disabled");
5805
5806 // FIXME
5807 // CM's reference processing also cleans up the string and symbol tables.
5808 // Should we do that here also? We could, but it is a serial operation
5809 // and could significantly increase the pause time.
5810
5811 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5812 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5813 }
5814
5815 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5816 _expand_heap_after_alloc_failure = true;
5817 _evacuation_failed = false;
5818
5819 // Should G1EvacuationFailureALot be in effect for this GC?
5820 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5821
5822 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5823
5824 // Disable the hot card cache.
5825 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5826 hot_card_cache->reset_hot_cache_claimed_index();
5827 hot_card_cache->set_use_cache(false);
5828
5829 uint n_workers;
5830 if (G1CollectedHeap::use_parallel_gc_threads()) {
5831 n_workers =
5832 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5833 workers()->active_workers(),
5834 Threads::number_of_non_daemon_threads());
5835 assert(UseDynamicNumberOfGCThreads ||
5836 n_workers == workers()->total_workers(),
5837 "If not dynamic should be using all the workers");
5838 workers()->set_active_workers(n_workers);
5839 set_par_threads(n_workers);
5840 } else {
5841 assert(n_par_threads() == 0,
5842 "Should be the original non-parallel value");
5843 n_workers = 1;
5844 }
5845
5846 G1ParTask g1_par_task(this, _task_queues);
5847
5848 init_for_evac_failure(NULL);
5849
5850 rem_set()->prepare_for_younger_refs_iterate(true);
5851
5852 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5853 double start_par_time_sec = os::elapsedTime();
5854 double end_par_time_sec;
5855
5856 {
5857 StrongRootsScope srs(this);
5858
5859 if (G1CollectedHeap::use_parallel_gc_threads()) {
5860 // The individual threads will set their evac-failure closures.
5861 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5862 // These tasks use ShareHeap::_process_strong_tasks
5863 assert(UseDynamicNumberOfGCThreads ||
5864 workers()->active_workers() == workers()->total_workers(),
5865 "If not dynamic should be using all the workers");
5866 workers()->run_task(&g1_par_task);
5867 } else {
5868 g1_par_task.set_for_termination(n_workers);
5869 g1_par_task.work(0);
5870 }
5871 end_par_time_sec = os::elapsedTime();
5872
5873 // Closing the inner scope will execute the destructor
5874 // for the StrongRootsScope object. We record the current
5875 // elapsed time before closing the scope so that time
5876 // taken for the SRS destructor is NOT included in the
5877 // reported parallel time.
5878 }
5879
5880 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5881 g1_policy()->phase_times()->record_par_time(par_time_ms);
5882
5883 double code_root_fixup_time_ms =
5884 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5885 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5886
5887 set_par_threads(0);
5888
5889 // Process any discovered reference objects - we have
5890 // to do this _before_ we retire the GC alloc regions
5891 // as we may have to copy some 'reachable' referent
5892 // objects (and their reachable sub-graphs) that were
5893 // not copied during the pause.
5894 process_discovered_references(n_workers);
5895
5896 // Weak root processing.
5897 {
5898 G1STWIsAliveClosure is_alive(this);
5899 G1KeepAliveClosure keep_alive(this);
5900 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5901 if (G1StringDedup::is_enabled()) {
5902 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5903 }
5904 }
5905
5906 release_gc_alloc_regions(n_workers, evacuation_info);
5907 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5908
5909 // Reset and re-enable the hot card cache.
5910 // Note the counts for the cards in the regions in the
5911 // collection set are reset when the collection set is freed.
5912 hot_card_cache->reset_hot_cache();
5913 hot_card_cache->set_use_cache(true);
5914
5915 // Migrate the strong code roots attached to each region in
5916 // the collection set. Ideally we would like to do this
5917 // after we have finished the scanning/evacuation of the
5918 // strong code roots for a particular heap region.
5919 migrate_strong_code_roots();
5920
5921 purge_code_root_memory();
5922
5923 if (g1_policy()->during_initial_mark_pause()) {
5924 // Reset the claim values set during marking the strong code roots
5925 reset_heap_region_claim_values();
5926 }
5927
5928 finalize_for_evac_failure();
5929
5930 if (evacuation_failed()) {
5931 remove_self_forwarding_pointers();
5932
5933 // Reset the G1EvacuationFailureALot counters and flags
5934 // Note: the values are reset only when an actual
5935 // evacuation failure occurs.
5936 NOT_PRODUCT(reset_evacuation_should_fail();)
5937 }
5938
5939 // Enqueue any remaining references remaining on the STW
5940 // reference processor's discovered lists. We need to do
5941 // this after the card table is cleaned (and verified) as
5942 // the act of enqueueing entries on to the pending list
5943 // will log these updates (and dirty their associated
5944 // cards). We need these updates logged to update any
5945 // RSets.
5946 enqueue_discovered_references(n_workers);
5947
5948 if (G1DeferredRSUpdate) {
5949 redirty_logged_cards();
5950 }
5951 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5952 }
5953
5954 void G1CollectedHeap::free_region(HeapRegion* hr,
5955 FreeRegionList* free_list,
5956 bool par,
5957 bool locked) {
5958 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5959 assert(!hr->is_empty(), "the region should not be empty");
5960 assert(free_list != NULL, "pre-condition");
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 #endif
6097
6098 void G1CollectedHeap::cleanUpCardTable() {
6099 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6100 double start = os::elapsedTime();
6101
6102 {
6103 // Iterate over the dirty cards region list.
6104 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6105
6106 if (G1CollectedHeap::use_parallel_gc_threads()) {
6107 set_par_threads();
6108 workers()->run_task(&cleanup_task);
6109 set_par_threads(0);
6110 } else {
6111 while (_dirty_cards_region_list) {
6112 HeapRegion* r = _dirty_cards_region_list;
6113 cleanup_task.clear_cards(r);
6114 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6115 if (_dirty_cards_region_list == r) {
6116 // The last region.
6117 _dirty_cards_region_list = NULL;
6118 }
6119 r->set_next_dirty_cards_region(NULL);
6120 }
6121 }
6122 #ifndef PRODUCT
6123 if (G1VerifyCTCleanup || VerifyAfterGC) {
6124 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6125 heap_region_iterate(&cleanup_verifier);
6126 }
6127 #endif
6128 }
6129
6130 double elapsed = os::elapsedTime() - start;
6131 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6132 }
6133
6134 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6135 size_t pre_used = 0;
6136 FreeRegionList local_free_list("Local List for CSet Freeing");
6137
6138 double young_time_ms = 0.0;
6139 double non_young_time_ms = 0.0;
6140
6141 // Since the collection set is a superset of the the young list,
6142 // all we need to do to clear the young list is clear its
6143 // head and length, and unlink any young regions in the code below
6144 _young_list->clear();
6145
6146 G1CollectorPolicy* policy = g1_policy();
6147
6148 double start_sec = os::elapsedTime();
6149 bool non_young = true;
6150
6151 HeapRegion* cur = cs_head;
6152 int age_bound = -1;
6153 size_t rs_lengths = 0;
6154
6155 while (cur != NULL) {
6156 assert(!is_on_master_free_list(cur), "sanity");
6157 if (non_young) {
6158 if (cur->is_young()) {
6159 double end_sec = os::elapsedTime();
6160 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6161 non_young_time_ms += elapsed_ms;
6162
6163 start_sec = os::elapsedTime();
6164 non_young = false;
6165 }
6166 } else {
6167 if (!cur->is_young()) {
6168 double end_sec = os::elapsedTime();
6169 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6170 young_time_ms += elapsed_ms;
6171
6172 start_sec = os::elapsedTime();
6173 non_young = true;
6174 }
6175 }
6176
6177 rs_lengths += cur->rem_set()->occupied_locked();
6178
6179 HeapRegion* next = cur->next_in_collection_set();
6180 assert(cur->in_collection_set(), "bad CS");
6181 cur->set_next_in_collection_set(NULL);
6182 cur->set_in_collection_set(false);
6183
6184 if (cur->is_young()) {
6185 int index = cur->young_index_in_cset();
6186 assert(index != -1, "invariant");
6187 assert((uint) index < policy->young_cset_region_length(), "invariant");
6188 size_t words_survived = _surviving_young_words[index];
6189 cur->record_surv_words_in_group(words_survived);
6190
6191 // At this point the we have 'popped' cur from the collection set
6192 // (linked via next_in_collection_set()) but it is still in the
6193 // young list (linked via next_young_region()). Clear the
6194 // _next_young_region field.
6195 cur->set_next_young_region(NULL);
6196 } else {
6197 int index = cur->young_index_in_cset();
6198 assert(index == -1, "invariant");
6199 }
6200
6201 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6202 (!cur->is_young() && cur->young_index_in_cset() == -1),
6203 "invariant" );
6204
6205 if (!cur->evacuation_failed()) {
6206 MemRegion used_mr = cur->used_region();
6207
6208 // And the region is empty.
6209 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6210 pre_used += cur->used();
6211 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6212 } else {
6213 cur->uninstall_surv_rate_group();
6214 if (cur->is_young()) {
6215 cur->set_young_index_in_cset(-1);
6216 }
6217 cur->set_not_young();
6218 cur->set_evacuation_failed(false);
6219 // The region is now considered to be old.
6220 _old_set.add(cur);
6221 evacuation_info.increment_collectionset_used_after(cur->used());
6222 }
6223 cur = next;
6224 }
6225
6226 evacuation_info.set_regions_freed(local_free_list.length());
6227 policy->record_max_rs_lengths(rs_lengths);
6228 policy->cset_regions_freed();
6229
6230 double end_sec = os::elapsedTime();
6231 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6232
6233 if (non_young) {
6234 non_young_time_ms += elapsed_ms;
6235 } else {
6236 young_time_ms += elapsed_ms;
6237 }
6238
6239 prepend_to_freelist(&local_free_list);
6240 decrement_summary_bytes(pre_used);
6241 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6242 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6243 }
6244
6245 // This routine is similar to the above but does not record
6246 // any policy statistics or update free lists; we are abandoning
6247 // the current incremental collection set in preparation of a
6248 // full collection. After the full GC we will start to build up
6249 // the incremental collection set again.
6250 // This is only called when we're doing a full collection
6251 // and is immediately followed by the tearing down of the young list.
6252
6253 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6254 HeapRegion* cur = cs_head;
6255
6256 while (cur != NULL) {
6257 HeapRegion* next = cur->next_in_collection_set();
6258 assert(cur->in_collection_set(), "bad CS");
6259 cur->set_next_in_collection_set(NULL);
6260 cur->set_in_collection_set(false);
6261 cur->set_young_index_in_cset(-1);
6262 cur = next;
6263 }
6264 }
6265
6266 void G1CollectedHeap::set_free_regions_coming() {
6267 if (G1ConcRegionFreeingVerbose) {
6268 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6269 "setting free regions coming");
6270 }
6271
6272 assert(!free_regions_coming(), "pre-condition");
6273 _free_regions_coming = true;
6274 }
6275
6276 void G1CollectedHeap::reset_free_regions_coming() {
6277 assert(free_regions_coming(), "pre-condition");
6278
6279 {
6280 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6281 _free_regions_coming = false;
6282 SecondaryFreeList_lock->notify_all();
6283 }
6284
6285 if (G1ConcRegionFreeingVerbose) {
6286 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6287 "reset free regions coming");
6288 }
6289 }
6290
6291 void G1CollectedHeap::wait_while_free_regions_coming() {
6292 // Most of the time we won't have to wait, so let's do a quick test
6293 // first before we take the lock.
6294 if (!free_regions_coming()) {
6295 return;
6296 }
6297
6298 if (G1ConcRegionFreeingVerbose) {
6299 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6300 "waiting for free regions");
6301 }
6302
6303 {
6304 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6305 while (free_regions_coming()) {
6306 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6307 }
6308 }
6309
6310 if (G1ConcRegionFreeingVerbose) {
6311 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6312 "done waiting for free regions");
6313 }
6314 }
6315
6316 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6317 assert(heap_lock_held_for_gc(),
6318 "the heap lock should already be held by or for this thread");
6319 _young_list->push_region(hr);
6320 }
6321
6322 class NoYoungRegionsClosure: public HeapRegionClosure {
6323 private:
6324 bool _success;
6325 public:
6326 NoYoungRegionsClosure() : _success(true) { }
6327 bool doHeapRegion(HeapRegion* r) {
6328 if (r->is_young()) {
6329 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6330 r->bottom(), r->end());
6331 _success = false;
6332 }
6333 return false;
6334 }
6335 bool success() { return _success; }
6336 };
6337
6338 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6339 bool ret = _young_list->check_list_empty(check_sample);
6340
6341 if (check_heap) {
6342 NoYoungRegionsClosure closure;
6343 heap_region_iterate(&closure);
6344 ret = ret && closure.success();
6345 }
6346
6347 return ret;
6348 }
6349
6350 class TearDownRegionSetsClosure : public HeapRegionClosure {
6351 private:
6352 HeapRegionSet *_old_set;
6353
6354 public:
6355 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6356
6357 bool doHeapRegion(HeapRegion* r) {
6358 if (r->is_empty()) {
6359 // We ignore empty regions, we'll empty the free list afterwards
6360 } else if (r->is_young()) {
6361 // We ignore young regions, we'll empty the young list afterwards
6362 } else if (r->isHumongous()) {
6363 // We ignore humongous regions, we're not tearing down the
6364 // humongous region set
6365 } else {
6366 // The rest should be old
6367 _old_set->remove(r);
6368 }
6369 return false;
6370 }
6371
6372 ~TearDownRegionSetsClosure() {
6373 assert(_old_set->is_empty(), "post-condition");
6374 }
6375 };
6376
6377 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6378 assert_at_safepoint(true /* should_be_vm_thread */);
6379
6380 if (!free_list_only) {
6381 TearDownRegionSetsClosure cl(&_old_set);
6382 heap_region_iterate(&cl);
6383
6384 // Note that emptying the _young_list is postponed and instead done as
6385 // the first step when rebuilding the regions sets again. The reason for
6386 // this is that during a full GC string deduplication needs to know if
6387 // a collected region was young or old when the full GC was initiated.
6388 }
6389 _free_list.remove_all();
6390 }
6391
6392 class RebuildRegionSetsClosure : public HeapRegionClosure {
6393 private:
6394 bool _free_list_only;
6395 HeapRegionSet* _old_set;
6396 FreeRegionList* _free_list;
6397 size_t _total_used;
6398
6399 public:
6400 RebuildRegionSetsClosure(bool free_list_only,
6401 HeapRegionSet* old_set, FreeRegionList* free_list) :
6402 _free_list_only(free_list_only),
6403 _old_set(old_set), _free_list(free_list), _total_used(0) {
6404 assert(_free_list->is_empty(), "pre-condition");
6405 if (!free_list_only) {
6406 assert(_old_set->is_empty(), "pre-condition");
6407 }
6408 }
6409
6410 bool doHeapRegion(HeapRegion* r) {
6411 if (r->continuesHumongous()) {
6412 return false;
6413 }
6414
6415 if (r->is_empty()) {
6416 // Add free regions to the free list
6417 _free_list->add_as_tail(r);
6418 } else if (!_free_list_only) {
6419 assert(!r->is_young(), "we should not come across young regions");
6420
6421 if (r->isHumongous()) {
6422 // We ignore humongous regions, we left the humongous set unchanged
6423 } else {
6424 // The rest should be old, add them to the old set
6425 _old_set->add(r);
6426 }
6427 _total_used += r->used();
6428 }
6429
6430 return false;
6431 }
6432
6433 size_t total_used() {
6434 return _total_used;
6435 }
6436 };
6437
6438 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6439 assert_at_safepoint(true /* should_be_vm_thread */);
6440
6441 if (!free_list_only) {
6442 _young_list->empty_list();
6443 }
6444
6445 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6446 heap_region_iterate(&cl);
6447
6448 if (!free_list_only) {
6449 _summary_bytes_used = cl.total_used();
6450 }
6451 assert(_summary_bytes_used == recalculate_used(),
6452 err_msg("inconsistent _summary_bytes_used, "
6453 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6454 _summary_bytes_used, recalculate_used()));
6455 }
6456
6457 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6458 _refine_cte_cl->set_concurrent(concurrent);
6459 }
6460
6461 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6462 HeapRegion* hr = heap_region_containing(p);
6463 if (hr == NULL) {
6464 return false;
6465 } else {
6466 return hr->is_in(p);
6467 }
6468 }
6469
6470 // Methods for the mutator alloc region
6471
6472 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6473 bool force) {
6474 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6475 assert(!force || g1_policy()->can_expand_young_list(),
6476 "if force is true we should be able to expand the young list");
6477 bool young_list_full = g1_policy()->is_young_list_full();
6478 if (force || !young_list_full) {
6479 HeapRegion* new_alloc_region = new_region(word_size,
6480 false /* is_old */,
6481 false /* do_expand */);
6482 if (new_alloc_region != NULL) {
6483 set_region_short_lived_locked(new_alloc_region);
6484 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6485 return new_alloc_region;
6486 }
6487 }
6488 return NULL;
6489 }
6490
6491 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6492 size_t allocated_bytes) {
6493 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6494 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6495
6496 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6497 _summary_bytes_used += allocated_bytes;
6498 _hr_printer.retire(alloc_region);
6499 // We update the eden sizes here, when the region is retired,
6500 // instead of when it's allocated, since this is the point that its
6501 // used space has been recored in _summary_bytes_used.
6502 g1mm()->update_eden_size();
6503 }
6504
6505 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6506 bool force) {
6507 return _g1h->new_mutator_alloc_region(word_size, force);
6508 }
6509
6510 void G1CollectedHeap::set_par_threads() {
6511 // Don't change the number of workers. Use the value previously set
6512 // in the workgroup.
6513 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6514 uint n_workers = workers()->active_workers();
6515 assert(UseDynamicNumberOfGCThreads ||
6516 n_workers == workers()->total_workers(),
6517 "Otherwise should be using the total number of workers");
6518 if (n_workers == 0) {
6519 assert(false, "Should have been set in prior evacuation pause.");
6520 n_workers = ParallelGCThreads;
6521 workers()->set_active_workers(n_workers);
6522 }
6523 set_par_threads(n_workers);
6524 }
6525
6526 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6527 size_t allocated_bytes) {
6528 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6529 }
6530
6531 // Methods for the GC alloc regions
6532
6533 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6534 uint count,
6535 GCAllocPurpose ap) {
6536 assert(FreeList_lock->owned_by_self(), "pre-condition");
6537
6538 if (count < g1_policy()->max_regions(ap)) {
6539 bool survivor = (ap == GCAllocForSurvived);
6540 HeapRegion* new_alloc_region = new_region(word_size,
6541 !survivor,
6542 true /* do_expand */);
6543 if (new_alloc_region != NULL) {
6544 // We really only need to do this for old regions given that we
6545 // should never scan survivors. But it doesn't hurt to do it
6546 // for survivors too.
6547 new_alloc_region->set_saved_mark();
6548 if (survivor) {
6549 new_alloc_region->set_survivor();
6550 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6551 } else {
6552 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6553 }
6554 bool during_im = g1_policy()->during_initial_mark_pause();
6555 new_alloc_region->note_start_of_copying(during_im);
6556 return new_alloc_region;
6557 } else {
6558 g1_policy()->note_alloc_region_limit_reached(ap);
6559 }
6560 }
6561 return NULL;
6562 }
6563
6564 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6565 size_t allocated_bytes,
6566 GCAllocPurpose ap) {
6567 bool during_im = g1_policy()->during_initial_mark_pause();
6568 alloc_region->note_end_of_copying(during_im);
6569 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6570 if (ap == GCAllocForSurvived) {
6571 young_list()->add_survivor_region(alloc_region);
6572 } else {
6573 _old_set.add(alloc_region);
6574 }
6575 _hr_printer.retire(alloc_region);
6576 }
6577
6578 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6579 bool force) {
6580 assert(!force, "not supported for GC alloc regions");
6581 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6582 }
6583
6584 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6585 size_t allocated_bytes) {
6586 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6587 GCAllocForSurvived);
6588 }
6589
6590 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6591 bool force) {
6592 assert(!force, "not supported for GC alloc regions");
6593 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6594 }
6595
6596 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6597 size_t allocated_bytes) {
6598 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6599 GCAllocForTenured);
6600 }
6601 // Heap region set verification
6602
6603 class VerifyRegionListsClosure : public HeapRegionClosure {
6604 private:
6605 HeapRegionSet* _old_set;
6606 HeapRegionSet* _humongous_set;
6607 FreeRegionList* _free_list;
6608
6609 public:
6610 HeapRegionSetCount _old_count;
6611 HeapRegionSetCount _humongous_count;
6612 HeapRegionSetCount _free_count;
6613
6614 VerifyRegionListsClosure(HeapRegionSet* old_set,
6615 HeapRegionSet* humongous_set,
6616 FreeRegionList* free_list) :
6617 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6618 _old_count(), _humongous_count(), _free_count(){ }
6619
6620 bool doHeapRegion(HeapRegion* hr) {
6621 if (hr->continuesHumongous()) {
6622 return false;
6623 }
6624
6625 if (hr->is_young()) {
6626 // TODO
6627 } else if (hr->startsHumongous()) {
6628 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6629 _humongous_count.increment(1u, hr->capacity());
6630 } else if (hr->is_empty()) {
6631 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6632 _free_count.increment(1u, hr->capacity());
6633 } else {
6634 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6635 _old_count.increment(1u, hr->capacity());
6636 }
6637 return false;
6638 }
6639
6640 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6641 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6642 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6643 old_set->total_capacity_bytes(), _old_count.capacity()));
6644
6645 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6646 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6647 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6648
6649 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6650 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6651 free_list->total_capacity_bytes(), _free_count.capacity()));
6652 }
6653 };
6654
6655 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6656 HeapWord* bottom) {
6657 HeapWord* end = bottom + HeapRegion::GrainWords;
6658 MemRegion mr(bottom, end);
6659 assert(_g1_reserved.contains(mr), "invariant");
6660 // This might return NULL if the allocation fails
6661 return new HeapRegion(hrs_index, _bot_shared, mr);
6662 }
6663
6664 void G1CollectedHeap::verify_region_sets() {
6665 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6666
6667 // First, check the explicit lists.
6668 _free_list.verify_list();
6669 {
6670 // Given that a concurrent operation might be adding regions to
6671 // the secondary free list we have to take the lock before
6672 // verifying it.
6673 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6674 _secondary_free_list.verify_list();
6675 }
6676
6677 // If a concurrent region freeing operation is in progress it will
6678 // be difficult to correctly attributed any free regions we come
6679 // across to the correct free list given that they might belong to
6680 // one of several (free_list, secondary_free_list, any local lists,
6681 // etc.). So, if that's the case we will skip the rest of the
6682 // verification operation. Alternatively, waiting for the concurrent
6683 // operation to complete will have a non-trivial effect on the GC's
6684 // operation (no concurrent operation will last longer than the
6685 // interval between two calls to verification) and it might hide
6686 // any issues that we would like to catch during testing.
6687 if (free_regions_coming()) {
6688 return;
6689 }
6690
6691 // Make sure we append the secondary_free_list on the free_list so
6692 // that all free regions we will come across can be safely
6693 // attributed to the free_list.
6694 append_secondary_free_list_if_not_empty_with_lock();
6695
6696 // Finally, make sure that the region accounting in the lists is
6697 // consistent with what we see in the heap.
6698
6699 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6700 heap_region_iterate(&cl);
6701 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6702 }
6703
6704 // Optimized nmethod scanning
6705
6706 class RegisterNMethodOopClosure: public OopClosure {
6707 G1CollectedHeap* _g1h;
6708 nmethod* _nm;
6709
6710 template <class T> void do_oop_work(T* p) {
6711 T heap_oop = oopDesc::load_heap_oop(p);
6712 if (!oopDesc::is_null(heap_oop)) {
6713 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6714 HeapRegion* hr = _g1h->heap_region_containing(obj);
6715 assert(!hr->continuesHumongous(),
6716 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6717 " starting at "HR_FORMAT,
6718 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6719
6720 // HeapRegion::add_strong_code_root() avoids adding duplicate
6721 // entries but having duplicates is OK since we "mark" nmethods
6722 // as visited when we scan the strong code root lists during the GC.
6723 hr->add_strong_code_root(_nm);
6724 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6725 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6726 _nm, HR_FORMAT_PARAMS(hr)));
6727 }
6728 }
6729
6730 public:
6731 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6732 _g1h(g1h), _nm(nm) {}
6733
6734 void do_oop(oop* p) { do_oop_work(p); }
6735 void do_oop(narrowOop* p) { do_oop_work(p); }
6736 };
6737
6738 class UnregisterNMethodOopClosure: public OopClosure {
6739 G1CollectedHeap* _g1h;
6740 nmethod* _nm;
6741
6742 template <class T> void do_oop_work(T* p) {
6743 T heap_oop = oopDesc::load_heap_oop(p);
6744 if (!oopDesc::is_null(heap_oop)) {
6745 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6746 HeapRegion* hr = _g1h->heap_region_containing(obj);
6747 assert(!hr->continuesHumongous(),
6748 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6749 " starting at "HR_FORMAT,
6750 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6751
6752 hr->remove_strong_code_root(_nm);
6753 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6754 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6755 _nm, HR_FORMAT_PARAMS(hr)));
6756 }
6757 }
6758
6759 public:
6760 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6761 _g1h(g1h), _nm(nm) {}
6762
6763 void do_oop(oop* p) { do_oop_work(p); }
6764 void do_oop(narrowOop* p) { do_oop_work(p); }
6765 };
6766
6767 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6768 CollectedHeap::register_nmethod(nm);
6769
6770 guarantee(nm != NULL, "sanity");
6771 RegisterNMethodOopClosure reg_cl(this, nm);
6772 nm->oops_do(®_cl);
6773 }
6774
6775 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6776 CollectedHeap::unregister_nmethod(nm);
6777
6778 guarantee(nm != NULL, "sanity");
6779 UnregisterNMethodOopClosure reg_cl(this, nm);
6780 nm->oops_do(®_cl, true);
6781 }
6782
6783 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6784 public:
6785 bool doHeapRegion(HeapRegion *hr) {
6786 assert(!hr->isHumongous(),
6787 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6788 HR_FORMAT_PARAMS(hr)));
6789 hr->migrate_strong_code_roots();
6790 return false;
6791 }
6792 };
6793
6794 void G1CollectedHeap::migrate_strong_code_roots() {
6795 MigrateCodeRootsHeapRegionClosure cl;
6796 double migrate_start = os::elapsedTime();
6797 collection_set_iterate(&cl);
6798 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6799 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6800 }
6801
6802 void G1CollectedHeap::purge_code_root_memory() {
6803 double purge_start = os::elapsedTime();
6804 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6805 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6806 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6807 }
6808
6809 // Mark all the code roots that point into regions *not* in the
6810 // collection set.
6811 //
6812 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6813 // walking the the code roots lists of regions not in the collection
6814 // set. Suppose we have an nmethod (M) that points to objects in two
6815 // separate regions - one in the collection set (R1) and one not (R2).
6816 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6817 // nmethod M when walking the code roots for R1. When we come to scan
6818 // the code roots for R2, we would see that M is already marked and it
6819 // would be skipped and the objects in R2 that are referenced from M
6820 // would not be evacuated.
6821
6822 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6823
6824 class MarkStrongCodeRootOopClosure: public OopClosure {
6825 ConcurrentMark* _cm;
6826 HeapRegion* _hr;
6827 uint _worker_id;
6828
6829 template <class T> void do_oop_work(T* p) {
6830 T heap_oop = oopDesc::load_heap_oop(p);
6831 if (!oopDesc::is_null(heap_oop)) {
6832 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6833 // Only mark objects in the region (which is assumed
6834 // to be not in the collection set).
6835 if (_hr->is_in(obj)) {
6836 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6837 }
6838 }
6839 }
6840
6841 public:
6842 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6843 _cm(cm), _hr(hr), _worker_id(worker_id) {
6844 assert(!_hr->in_collection_set(), "sanity");
6845 }
6846
6847 void do_oop(narrowOop* p) { do_oop_work(p); }
6848 void do_oop(oop* p) { do_oop_work(p); }
6849 };
6850
6851 MarkStrongCodeRootOopClosure _oop_cl;
6852
6853 public:
6854 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6855 _oop_cl(cm, hr, worker_id) {}
6856
6857 void do_code_blob(CodeBlob* cb) {
6858 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6859 if (nm != NULL) {
6860 nm->oops_do(&_oop_cl);
6861 }
6862 }
6863 };
6864
6865 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6866 G1CollectedHeap* _g1h;
6867 uint _worker_id;
6868
6869 public:
6870 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6871 _g1h(g1h), _worker_id(worker_id) {}
6872
6873 bool doHeapRegion(HeapRegion *hr) {
6874 HeapRegionRemSet* hrrs = hr->rem_set();
6875 if (hr->continuesHumongous()) {
6876 // Code roots should never be attached to a continuation of a humongous region
6877 assert(hrrs->strong_code_roots_list_length() == 0,
6878 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6879 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6880 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6881 hrrs->strong_code_roots_list_length()));
6882 return false;
6883 }
6884
6885 if (hr->in_collection_set()) {
6886 // Don't mark code roots into regions in the collection set here.
6887 // They will be marked when we scan them.
6888 return false;
6889 }
6890
6891 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6892 hr->strong_code_roots_do(&cb_cl);
6893 return false;
6894 }
6895 };
6896
6897 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6898 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6899 if (G1CollectedHeap::use_parallel_gc_threads()) {
6900 heap_region_par_iterate_chunked(&cl,
6901 worker_id,
6902 workers()->active_workers(),
6903 HeapRegion::ParMarkRootClaimValue);
6904 } else {
6905 heap_region_iterate(&cl);
6906 }
6907 }
6908
6909 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6910 G1CollectedHeap* _g1h;
6911
6912 public:
6913 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6914 _g1h(g1h) {}
6915
6916 void do_code_blob(CodeBlob* cb) {
6917 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6918 if (nm == NULL) {
6919 return;
6920 }
6921
6922 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6923 _g1h->register_nmethod(nm);
6924 }
6925 }
6926 };
6927
6928 void G1CollectedHeap::rebuild_strong_code_roots() {
6929 RebuildStrongCodeRootClosure blob_cl(this);
6930 CodeCache::blobs_do(&blob_cl);
6931 }