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/globalDefinitions.hpp"
61 #include "utilities/ticks.hpp"
62
63 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
64
65 // turn it on so that the contents of the young list (scan-only /
66 // to-be-collected) are printed at "strategic" points before / during
67 // / after the collection --- this is useful for debugging
68 #define YOUNG_LIST_VERBOSE 0
69 // CURRENT STATUS
70 // This file is under construction. Search for "FIXME".
71
72 // INVARIANTS/NOTES
73 //
74 // All allocation activity covered by the G1CollectedHeap interface is
75 // serialized by acquiring the HeapLock. This happens in mem_allocate
76 // and allocate_new_tlab, which are the "entry" points to the
77 // allocation code from the rest of the JVM. (Note that this does not
78 // apply to TLAB allocation, which is not part of this interface: it
79 // is done by clients of this interface.)
80
81 // Notes on implementation of parallelism in different tasks.
82 //
83 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
84 // The number of GC workers is passed to heap_region_par_iterate_chunked().
85 // It does use run_task() which sets _n_workers in the task.
86 // G1ParTask executes g1_process_strong_roots() ->
87 // SharedHeap::process_strong_roots() which calls eventually to
88 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
89 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
90 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
91 //
92
93 // Local to this file.
94
95 class RefineCardTableEntryClosure: public CardTableEntryClosure {
96 bool _concurrent;
97 public:
98 RefineCardTableEntryClosure() : _concurrent(true) { }
99
100 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
101 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
102 // This path is executed by the concurrent refine or mutator threads,
103 // concurrently, and so we do not care if card_ptr contains references
104 // that point into the collection set.
105 assert(!oops_into_cset, "should be");
106
107 if (_concurrent && SuspendibleThreadSet::should_yield()) {
108 // Caller will actually yield.
109 return false;
110 }
111 // Otherwise, we finished successfully; return true.
112 return true;
113 }
114
115 void set_concurrent(bool b) { _concurrent = b; }
116 };
117
118
119 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
120 size_t _num_processed;
121 CardTableModRefBS* _ctbs;
122 int _histo[256];
123
124 public:
125 ClearLoggedCardTableEntryClosure() :
126 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
127 {
128 for (int i = 0; i < 256; i++) _histo[i] = 0;
129 }
130
131 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
132 unsigned char* ujb = (unsigned char*)card_ptr;
133 int ind = (int)(*ujb);
134 _histo[ind]++;
135
136 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
137 _num_processed++;
138
139 return true;
140 }
141
142 size_t num_processed() { return _num_processed; }
143
144 void print_histo() {
145 gclog_or_tty->print_cr("Card table value histogram:");
146 for (int i = 0; i < 256; i++) {
147 if (_histo[i] != 0) {
148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
149 }
150 }
151 }
152 };
153
154 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
155 private:
156 size_t _num_processed;
157
158 public:
159 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
160
161 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
162 *card_ptr = CardTableModRefBS::dirty_card_val();
163 _num_processed++;
164 return true;
165 }
166
167 size_t num_processed() const { return _num_processed; }
168 };
169
170 YoungList::YoungList(G1CollectedHeap* g1h) :
171 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
172 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
173 guarantee(check_list_empty(false), "just making sure...");
174 }
175
176 void YoungList::push_region(HeapRegion *hr) {
177 assert(!hr->is_young(), "should not already be young");
178 assert(hr->get_next_young_region() == NULL, "cause it should!");
179
180 hr->set_next_young_region(_head);
181 _head = hr;
182
183 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
184 ++_length;
185 }
186
187 void YoungList::add_survivor_region(HeapRegion* hr) {
188 assert(hr->is_survivor(), "should be flagged as survivor region");
189 assert(hr->get_next_young_region() == NULL, "cause it should!");
190
191 hr->set_next_young_region(_survivor_head);
192 if (_survivor_head == NULL) {
193 _survivor_tail = hr;
194 }
195 _survivor_head = hr;
196 ++_survivor_length;
197 }
198
199 void YoungList::empty_list(HeapRegion* list) {
200 while (list != NULL) {
201 HeapRegion* next = list->get_next_young_region();
202 list->set_next_young_region(NULL);
203 list->uninstall_surv_rate_group();
204 list->set_not_young();
205 list = next;
206 }
207 }
208
209 void YoungList::empty_list() {
210 assert(check_list_well_formed(), "young list should be well formed");
211
212 empty_list(_head);
213 _head = NULL;
214 _length = 0;
215
216 empty_list(_survivor_head);
217 _survivor_head = NULL;
218 _survivor_tail = NULL;
219 _survivor_length = 0;
220
221 _last_sampled_rs_lengths = 0;
222
223 assert(check_list_empty(false), "just making sure...");
224 }
225
226 bool YoungList::check_list_well_formed() {
227 bool ret = true;
228
229 uint length = 0;
230 HeapRegion* curr = _head;
231 HeapRegion* last = NULL;
232 while (curr != NULL) {
233 if (!curr->is_young()) {
234 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
235 "incorrectly tagged (y: %d, surv: %d)",
236 curr->bottom(), curr->end(),
237 curr->is_young(), curr->is_survivor());
238 ret = false;
239 }
240 ++length;
241 last = curr;
242 curr = curr->get_next_young_region();
243 }
244 ret = ret && (length == _length);
245
246 if (!ret) {
247 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
248 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
249 length, _length);
250 }
251
252 return ret;
253 }
254
255 bool YoungList::check_list_empty(bool check_sample) {
256 bool ret = true;
257
258 if (_length != 0) {
259 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
260 _length);
261 ret = false;
262 }
263 if (check_sample && _last_sampled_rs_lengths != 0) {
264 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
265 ret = false;
266 }
267 if (_head != NULL) {
268 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
269 ret = false;
270 }
271 if (!ret) {
272 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
273 }
274
275 return ret;
276 }
277
278 void
279 YoungList::rs_length_sampling_init() {
280 _sampled_rs_lengths = 0;
281 _curr = _head;
282 }
283
284 bool
285 YoungList::rs_length_sampling_more() {
286 return _curr != NULL;
287 }
288
289 void
290 YoungList::rs_length_sampling_next() {
291 assert( _curr != NULL, "invariant" );
292 size_t rs_length = _curr->rem_set()->occupied();
293
294 _sampled_rs_lengths += rs_length;
295
296 // The current region may not yet have been added to the
297 // incremental collection set (it gets added when it is
298 // retired as the current allocation region).
299 if (_curr->in_collection_set()) {
300 // Update the collection set policy information for this region
301 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
302 }
303
304 _curr = _curr->get_next_young_region();
305 if (_curr == NULL) {
306 _last_sampled_rs_lengths = _sampled_rs_lengths;
307 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
308 }
309 }
310
311 void
312 YoungList::reset_auxilary_lists() {
313 guarantee( is_empty(), "young list should be empty" );
314 assert(check_list_well_formed(), "young list should be well formed");
315
316 // Add survivor regions to SurvRateGroup.
317 _g1h->g1_policy()->note_start_adding_survivor_regions();
318 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
319
320 int young_index_in_cset = 0;
321 for (HeapRegion* curr = _survivor_head;
322 curr != NULL;
323 curr = curr->get_next_young_region()) {
324 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
325
326 // The region is a non-empty survivor so let's add it to
327 // the incremental collection set for the next evacuation
328 // pause.
329 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
330 young_index_in_cset += 1;
331 }
332 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
333 _g1h->g1_policy()->note_stop_adding_survivor_regions();
334
335 _head = _survivor_head;
336 _length = _survivor_length;
337 if (_survivor_head != NULL) {
338 assert(_survivor_tail != NULL, "cause it shouldn't be");
339 assert(_survivor_length > 0, "invariant");
340 _survivor_tail->set_next_young_region(NULL);
341 }
342
343 // Don't clear the survivor list handles until the start of
344 // the next evacuation pause - we need it in order to re-tag
345 // the survivor regions from this evacuation pause as 'young'
346 // at the start of the next.
347
348 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
349
350 assert(check_list_well_formed(), "young list should be well formed");
351 }
352
353 void YoungList::print() {
354 HeapRegion* lists[] = {_head, _survivor_head};
355 const char* names[] = {"YOUNG", "SURVIVOR"};
356
357 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
358 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
359 HeapRegion *curr = lists[list];
360 if (curr == NULL)
361 gclog_or_tty->print_cr(" empty");
362 while (curr != NULL) {
363 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
364 HR_FORMAT_PARAMS(curr),
365 curr->prev_top_at_mark_start(),
366 curr->next_top_at_mark_start(),
367 curr->age_in_surv_rate_group_cond());
368 curr = curr->get_next_young_region();
369 }
370 }
371
372 gclog_or_tty->print_cr("");
373 }
374
375 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
376 {
377 // Claim the right to put the region on the dirty cards region list
378 // by installing a self pointer.
379 HeapRegion* next = hr->get_next_dirty_cards_region();
380 if (next == NULL) {
381 HeapRegion* res = (HeapRegion*)
382 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
383 NULL);
384 if (res == NULL) {
385 HeapRegion* head;
386 do {
387 // Put the region to the dirty cards region list.
388 head = _dirty_cards_region_list;
389 next = (HeapRegion*)
390 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
391 if (next == head) {
392 assert(hr->get_next_dirty_cards_region() == hr,
393 "hr->get_next_dirty_cards_region() != hr");
394 if (next == NULL) {
395 // The last region in the list points to itself.
396 hr->set_next_dirty_cards_region(hr);
397 } else {
398 hr->set_next_dirty_cards_region(next);
399 }
400 }
401 } while (next != head);
402 }
403 }
404 }
405
406 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
407 {
408 HeapRegion* head;
409 HeapRegion* hr;
410 do {
411 head = _dirty_cards_region_list;
412 if (head == NULL) {
413 return NULL;
414 }
415 HeapRegion* new_head = head->get_next_dirty_cards_region();
416 if (head == new_head) {
417 // The last region.
418 new_head = NULL;
419 }
420 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
421 head);
422 } while (hr != head);
423 assert(hr != NULL, "invariant");
424 hr->set_next_dirty_cards_region(NULL);
425 return hr;
426 }
427
428 void G1CollectedHeap::stop_conc_gc_threads() {
429 _cg1r->stop();
430 _cmThread->stop();
431 if (G1StringDedup::is_enabled()) {
432 G1StringDedup::stop();
433 }
434 }
435
436 #ifdef ASSERT
437 // A region is added to the collection set as it is retired
438 // so an address p can point to a region which will be in the
439 // collection set but has not yet been retired. This method
440 // therefore is only accurate during a GC pause after all
441 // regions have been retired. It is used for debugging
442 // to check if an nmethod has references to objects that can
443 // be move during a partial collection. Though it can be
444 // inaccurate, it is sufficient for G1 because the conservative
445 // implementation of is_scavengable() for G1 will indicate that
446 // all nmethods must be scanned during a partial collection.
447 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
448 if (p == NULL) {
449 return false;
450 }
451 return heap_region_containing(p)->in_collection_set();
452 }
453 #endif
454
455 // Returns true if the reference points to an object that
456 // can move in an incremental collection.
457 bool G1CollectedHeap::is_scavengable(const void* p) {
458 HeapRegion* hr = heap_region_containing(p);
459 return !hr->isHumongous();
460 }
461
462 void G1CollectedHeap::check_ct_logs_at_safepoint() {
463 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
464 CardTableModRefBS* ct_bs = g1_barrier_set();
465
466 // Count the dirty cards at the start.
467 CountNonCleanMemRegionClosure count1(this);
468 ct_bs->mod_card_iterate(&count1);
469 int orig_count = count1.n();
470
471 // First clear the logged cards.
472 ClearLoggedCardTableEntryClosure clear;
473 dcqs.apply_closure_to_all_completed_buffers(&clear);
474 dcqs.iterate_closure_all_threads(&clear, false);
475 clear.print_histo();
476
477 // Now ensure that there's no dirty cards.
478 CountNonCleanMemRegionClosure count2(this);
479 ct_bs->mod_card_iterate(&count2);
480 if (count2.n() != 0) {
481 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
482 count2.n(), orig_count);
483 }
484 guarantee(count2.n() == 0, "Card table should be clean.");
485
486 RedirtyLoggedCardTableEntryClosure redirty;
487 dcqs.apply_closure_to_all_completed_buffers(&redirty);
488 dcqs.iterate_closure_all_threads(&redirty, false);
489 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
490 clear.num_processed(), orig_count);
491 guarantee(redirty.num_processed() == clear.num_processed(),
492 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
493 redirty.num_processed(), clear.num_processed()));
494
495 CountNonCleanMemRegionClosure count3(this);
496 ct_bs->mod_card_iterate(&count3);
497 if (count3.n() != orig_count) {
498 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
499 orig_count, count3.n());
500 guarantee(count3.n() >= orig_count, "Should have restored them all.");
501 }
502 }
503
504 // Private class members.
505
506 G1CollectedHeap* G1CollectedHeap::_g1h;
507
508 // Private methods.
509
510 HeapRegion*
511 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
512 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
513 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
514 if (!_secondary_free_list.is_empty()) {
515 if (G1ConcRegionFreeingVerbose) {
516 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
517 "secondary_free_list has %u entries",
518 _secondary_free_list.length());
519 }
520 // It looks as if there are free regions available on the
521 // secondary_free_list. Let's move them to the free_list and try
522 // again to allocate from it.
523 append_secondary_free_list();
524
525 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
526 "empty we should have moved at least one entry to the free_list");
527 HeapRegion* res = _free_list.remove_region(is_old);
528 if (G1ConcRegionFreeingVerbose) {
529 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
530 "allocated "HR_FORMAT" from secondary_free_list",
531 HR_FORMAT_PARAMS(res));
532 }
533 return res;
534 }
535
536 // Wait here until we get notified either when (a) there are no
537 // more free regions coming or (b) some regions have been moved on
538 // the secondary_free_list.
539 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
540 }
541
542 if (G1ConcRegionFreeingVerbose) {
543 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
544 "could not allocate from secondary_free_list");
545 }
546 return NULL;
547 }
548
549 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
550 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
551 "the only time we use this to allocate a humongous region is "
552 "when we are allocating a single humongous region");
553
554 HeapRegion* res;
555 if (G1StressConcRegionFreeing) {
556 if (!_secondary_free_list.is_empty()) {
557 if (G1ConcRegionFreeingVerbose) {
558 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
559 "forced to look at the secondary_free_list");
560 }
561 res = new_region_try_secondary_free_list(is_old);
562 if (res != NULL) {
563 return res;
564 }
565 }
566 }
567
568 res = _free_list.remove_region(is_old);
569
570 if (res == NULL) {
571 if (G1ConcRegionFreeingVerbose) {
572 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
573 "res == NULL, trying the secondary_free_list");
574 }
575 res = new_region_try_secondary_free_list(is_old);
576 }
577 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
578 // Currently, only attempts to allocate GC alloc regions set
579 // do_expand to true. So, we should only reach here during a
580 // safepoint. If this assumption changes we might have to
581 // reconsider the use of _expand_heap_after_alloc_failure.
582 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
583
584 ergo_verbose1(ErgoHeapSizing,
585 "attempt heap expansion",
586 ergo_format_reason("region allocation request failed")
587 ergo_format_byte("allocation request"),
588 word_size * HeapWordSize);
589 if (expand(word_size * HeapWordSize)) {
590 // Given that expand() succeeded in expanding the heap, and we
591 // always expand the heap by an amount aligned to the heap
592 // region size, the free list should in theory not be empty.
593 // In either case remove_region() will check for NULL.
594 res = _free_list.remove_region(is_old);
595 } else {
596 _expand_heap_after_alloc_failure = false;
597 }
598 }
599 return res;
600 }
601
602 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
603 size_t word_size) {
604 assert(isHumongous(word_size), "word_size should be humongous");
605 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
606
607 uint first = G1_NULL_HRS_INDEX;
608 if (num_regions == 1) {
609 // Only one region to allocate, no need to go through the slower
610 // path. The caller will attempt the expansion if this fails, so
611 // let's not try to expand here too.
612 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
613 if (hr != NULL) {
614 first = hr->hrs_index();
615 } else {
616 first = G1_NULL_HRS_INDEX;
617 }
618 } else {
619 // We can't allocate humongous regions while cleanupComplete() is
620 // running, since some of the regions we find to be empty might not
621 // yet be added to the free list and it is not straightforward to
622 // know which list they are on so that we can remove them. Note
623 // that we only need to do this if we need to allocate more than
624 // one region to satisfy the current humongous allocation
625 // request. If we are only allocating one region we use the common
626 // region allocation code (see above).
627 wait_while_free_regions_coming();
628 append_secondary_free_list_if_not_empty_with_lock();
629
630 if (free_regions() >= num_regions) {
631 first = _hrs.find_contiguous(num_regions);
632 if (first != G1_NULL_HRS_INDEX) {
633 for (uint i = first; i < first + num_regions; ++i) {
634 HeapRegion* hr = region_at(i);
635 assert(hr->is_empty(), "sanity");
636 assert(is_on_master_free_list(hr), "sanity");
637 hr->set_pending_removal(true);
638 }
639 _free_list.remove_all_pending(num_regions);
640 }
641 }
642 }
643 return first;
644 }
645
646 HeapWord*
647 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
648 uint num_regions,
649 size_t word_size) {
650 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
651 assert(isHumongous(word_size), "word_size should be humongous");
652 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
653
654 // Index of last region in the series + 1.
655 uint last = first + num_regions;
656
657 // We need to initialize the region(s) we just discovered. This is
658 // a bit tricky given that it can happen concurrently with
659 // refinement threads refining cards on these regions and
660 // potentially wanting to refine the BOT as they are scanning
661 // those cards (this can happen shortly after a cleanup; see CR
662 // 6991377). So we have to set up the region(s) carefully and in
663 // a specific order.
664
665 // The word size sum of all the regions we will allocate.
666 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
667 assert(word_size <= word_size_sum, "sanity");
668
669 // This will be the "starts humongous" region.
670 HeapRegion* first_hr = region_at(first);
671 // The header of the new object will be placed at the bottom of
672 // the first region.
673 HeapWord* new_obj = first_hr->bottom();
674 // This will be the new end of the first region in the series that
675 // should also match the end of the last region in the series.
676 HeapWord* new_end = new_obj + word_size_sum;
677 // This will be the new top of the first region that will reflect
678 // this allocation.
679 HeapWord* new_top = new_obj + word_size;
680
681 // First, we need to zero the header of the space that we will be
682 // allocating. When we update top further down, some refinement
683 // threads might try to scan the region. By zeroing the header we
684 // ensure that any thread that will try to scan the region will
685 // come across the zero klass word and bail out.
686 //
687 // NOTE: It would not have been correct to have used
688 // CollectedHeap::fill_with_object() and make the space look like
689 // an int array. The thread that is doing the allocation will
690 // later update the object header to a potentially different array
691 // type and, for a very short period of time, the klass and length
692 // fields will be inconsistent. This could cause a refinement
693 // thread to calculate the object size incorrectly.
694 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
695
696 // We will set up the first region as "starts humongous". This
697 // will also update the BOT covering all the regions to reflect
698 // that there is a single object that starts at the bottom of the
699 // first region.
700 first_hr->set_startsHumongous(new_top, new_end);
701
702 // Then, if there are any, we will set up the "continues
703 // humongous" regions.
704 HeapRegion* hr = NULL;
705 for (uint i = first + 1; i < last; ++i) {
706 hr = region_at(i);
707 hr->set_continuesHumongous(first_hr);
708 }
709 // If we have "continues humongous" regions (hr != NULL), then the
710 // end of the last one should match new_end.
711 assert(hr == NULL || hr->end() == new_end, "sanity");
712
713 // Up to this point no concurrent thread would have been able to
714 // do any scanning on any region in this series. All the top
715 // fields still point to bottom, so the intersection between
716 // [bottom,top] and [card_start,card_end] will be empty. Before we
717 // update the top fields, we'll do a storestore to make sure that
718 // no thread sees the update to top before the zeroing of the
719 // object header and the BOT initialization.
720 OrderAccess::storestore();
721
722 // Now that the BOT and the object header have been initialized,
723 // we can update top of the "starts humongous" region.
724 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
725 "new_top should be in this region");
726 first_hr->set_top(new_top);
727 if (_hr_printer.is_active()) {
728 HeapWord* bottom = first_hr->bottom();
729 HeapWord* end = first_hr->orig_end();
730 if ((first + 1) == last) {
731 // the series has a single humongous region
732 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
733 } else {
734 // the series has more than one humongous regions
735 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
736 }
737 }
738
739 // Now, we will update the top fields of the "continues humongous"
740 // regions. The reason we need to do this is that, otherwise,
741 // these regions would look empty and this will confuse parts of
742 // G1. For example, the code that looks for a consecutive number
743 // of empty regions will consider them empty and try to
744 // re-allocate them. We can extend is_empty() to also include
745 // !continuesHumongous(), but it is easier to just update the top
746 // fields here. The way we set top for all regions (i.e., top ==
747 // end for all regions but the last one, top == new_top for the
748 // last one) is actually used when we will free up the humongous
749 // region in free_humongous_region().
750 hr = NULL;
751 for (uint i = first + 1; i < last; ++i) {
752 hr = region_at(i);
753 if ((i + 1) == last) {
754 // last continues humongous region
755 assert(hr->bottom() < new_top && new_top <= hr->end(),
756 "new_top should fall on this region");
757 hr->set_top(new_top);
758 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
759 } else {
760 // not last one
761 assert(new_top > hr->end(), "new_top should be above this region");
762 hr->set_top(hr->end());
763 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
764 }
765 }
766 // If we have continues humongous regions (hr != NULL), then the
767 // end of the last one should match new_end and its top should
768 // match new_top.
769 assert(hr == NULL ||
770 (hr->end() == new_end && hr->top() == new_top), "sanity");
771 check_bitmaps("Humongous Region Allocation", first_hr);
772
773 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
774 _summary_bytes_used += first_hr->used();
775 _humongous_set.add(first_hr);
776
777 return new_obj;
778 }
779
780 // If could fit into free regions w/o expansion, try.
781 // Otherwise, if can expand, do so.
782 // Otherwise, if using ex regions might help, try with ex given back.
783 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
784 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
785
786 verify_region_sets_optional();
787
788 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
789 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
790 uint x_num = expansion_regions();
791 uint fs = _hrs.free_suffix();
792 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
793 if (first == G1_NULL_HRS_INDEX) {
794 // The only thing we can do now is attempt expansion.
795 if (fs + x_num >= num_regions) {
796 // If the number of regions we're trying to allocate for this
797 // object is at most the number of regions in the free suffix,
798 // then the call to humongous_obj_allocate_find_first() above
799 // should have succeeded and we wouldn't be here.
800 //
801 // We should only be trying to expand when the free suffix is
802 // not sufficient for the object _and_ we have some expansion
803 // room available.
804 assert(num_regions > fs, "earlier allocation should have succeeded");
805
806 ergo_verbose1(ErgoHeapSizing,
807 "attempt heap expansion",
808 ergo_format_reason("humongous allocation request failed")
809 ergo_format_byte("allocation request"),
810 word_size * HeapWordSize);
811 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
812 // Even though the heap was expanded, it might not have
813 // reached the desired size. So, we cannot assume that the
814 // allocation will succeed.
815 first = humongous_obj_allocate_find_first(num_regions, word_size);
816 }
817 }
818 }
819
820 HeapWord* result = NULL;
821 if (first != G1_NULL_HRS_INDEX) {
822 result =
823 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
824 assert(result != NULL, "it should always return a valid result");
825
826 // A successful humongous object allocation changes the used space
827 // information of the old generation so we need to recalculate the
828 // sizes and update the jstat counters here.
829 g1mm()->update_sizes();
830 }
831
832 verify_region_sets_optional();
833
834 return result;
835 }
836
837 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
838 assert_heap_not_locked_and_not_at_safepoint();
839 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
840
841 unsigned int dummy_gc_count_before;
842 int dummy_gclocker_retry_count = 0;
843 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
844 }
845
846 HeapWord*
847 G1CollectedHeap::mem_allocate(size_t word_size,
848 bool* gc_overhead_limit_was_exceeded) {
849 assert_heap_not_locked_and_not_at_safepoint();
850
851 // Loop until the allocation is satisfied, or unsatisfied after GC.
852 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
853 unsigned int gc_count_before;
854
855 HeapWord* result = NULL;
856 if (!isHumongous(word_size)) {
857 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
858 } else {
859 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
860 }
861 if (result != NULL) {
862 return result;
863 }
864
865 // Create the garbage collection operation...
866 VM_G1CollectForAllocation op(gc_count_before, word_size);
867 // ...and get the VM thread to execute it.
868 VMThread::execute(&op);
869
870 if (op.prologue_succeeded() && op.pause_succeeded()) {
871 // If the operation was successful we'll return the result even
872 // if it is NULL. If the allocation attempt failed immediately
873 // after a Full GC, it's unlikely we'll be able to allocate now.
874 HeapWord* result = op.result();
875 if (result != NULL && !isHumongous(word_size)) {
876 // Allocations that take place on VM operations do not do any
877 // card dirtying and we have to do it here. We only have to do
878 // this for non-humongous allocations, though.
879 dirty_young_block(result, word_size);
880 }
881 return result;
882 } else {
883 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
884 return NULL;
885 }
886 assert(op.result() == NULL,
887 "the result should be NULL if the VM op did not succeed");
888 }
889
890 // Give a warning if we seem to be looping forever.
891 if ((QueuedAllocationWarningCount > 0) &&
892 (try_count % QueuedAllocationWarningCount == 0)) {
893 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
894 }
895 }
896
897 ShouldNotReachHere();
898 return NULL;
899 }
900
901 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
902 unsigned int *gc_count_before_ret,
903 int* gclocker_retry_count_ret) {
904 // Make sure you read the note in attempt_allocation_humongous().
905
906 assert_heap_not_locked_and_not_at_safepoint();
907 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
908 "be called for humongous allocation requests");
909
910 // We should only get here after the first-level allocation attempt
911 // (attempt_allocation()) failed to allocate.
912
913 // We will loop until a) we manage to successfully perform the
914 // allocation or b) we successfully schedule a collection which
915 // fails to perform the allocation. b) is the only case when we'll
916 // return NULL.
917 HeapWord* result = NULL;
918 for (int try_count = 1; /* we'll return */; try_count += 1) {
919 bool should_try_gc;
920 unsigned int gc_count_before;
921
922 {
923 MutexLockerEx x(Heap_lock);
924
925 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
926 false /* bot_updates */);
927 if (result != NULL) {
928 return result;
929 }
930
931 // If we reach here, attempt_allocation_locked() above failed to
932 // allocate a new region. So the mutator alloc region should be NULL.
933 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
934
935 if (GC_locker::is_active_and_needs_gc()) {
936 if (g1_policy()->can_expand_young_list()) {
937 // No need for an ergo verbose message here,
938 // can_expand_young_list() does this when it returns true.
939 result = _mutator_alloc_region.attempt_allocation_force(word_size,
940 false /* bot_updates */);
941 if (result != NULL) {
942 return result;
943 }
944 }
945 should_try_gc = false;
946 } else {
947 // The GCLocker may not be active but the GCLocker initiated
948 // GC may not yet have been performed (GCLocker::needs_gc()
949 // returns true). In this case we do not try this GC and
950 // wait until the GCLocker initiated GC is performed, and
951 // then retry the allocation.
952 if (GC_locker::needs_gc()) {
953 should_try_gc = false;
954 } else {
955 // Read the GC count while still holding the Heap_lock.
956 gc_count_before = total_collections();
957 should_try_gc = true;
958 }
959 }
960 }
961
962 if (should_try_gc) {
963 bool succeeded;
964 result = do_collection_pause(word_size, gc_count_before, &succeeded,
965 GCCause::_g1_inc_collection_pause);
966 if (result != NULL) {
967 assert(succeeded, "only way to get back a non-NULL result");
968 return result;
969 }
970
971 if (succeeded) {
972 // If we get here we successfully scheduled a collection which
973 // failed to allocate. No point in trying to allocate
974 // further. We'll just return NULL.
975 MutexLockerEx x(Heap_lock);
976 *gc_count_before_ret = total_collections();
977 return NULL;
978 }
979 } else {
980 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
981 MutexLockerEx x(Heap_lock);
982 *gc_count_before_ret = total_collections();
983 return NULL;
984 }
985 // The GCLocker is either active or the GCLocker initiated
986 // GC has not yet been performed. Stall until it is and
987 // then retry the allocation.
988 GC_locker::stall_until_clear();
989 (*gclocker_retry_count_ret) += 1;
990 }
991
992 // We can reach here if we were unsuccessful in scheduling a
993 // collection (because another thread beat us to it) or if we were
994 // stalled due to the GC locker. In either can we should retry the
995 // allocation attempt in case another thread successfully
996 // performed a collection and reclaimed enough space. We do the
997 // first attempt (without holding the Heap_lock) here and the
998 // follow-on attempt will be at the start of the next loop
999 // iteration (after taking the Heap_lock).
1000 result = _mutator_alloc_region.attempt_allocation(word_size,
1001 false /* bot_updates */);
1002 if (result != NULL) {
1003 return result;
1004 }
1005
1006 // Give a warning if we seem to be looping forever.
1007 if ((QueuedAllocationWarningCount > 0) &&
1008 (try_count % QueuedAllocationWarningCount == 0)) {
1009 warning("G1CollectedHeap::attempt_allocation_slow() "
1010 "retries %d times", try_count);
1011 }
1012 }
1013
1014 ShouldNotReachHere();
1015 return NULL;
1016 }
1017
1018 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1019 unsigned int * gc_count_before_ret,
1020 int* gclocker_retry_count_ret) {
1021 // The structure of this method has a lot of similarities to
1022 // attempt_allocation_slow(). The reason these two were not merged
1023 // into a single one is that such a method would require several "if
1024 // allocation is not humongous do this, otherwise do that"
1025 // conditional paths which would obscure its flow. In fact, an early
1026 // version of this code did use a unified method which was harder to
1027 // follow and, as a result, it had subtle bugs that were hard to
1028 // track down. So keeping these two methods separate allows each to
1029 // be more readable. It will be good to keep these two in sync as
1030 // much as possible.
1031
1032 assert_heap_not_locked_and_not_at_safepoint();
1033 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1034 "should only be called for humongous allocations");
1035
1036 // Humongous objects can exhaust the heap quickly, so we should check if we
1037 // need to start a marking cycle at each humongous object allocation. We do
1038 // the check before we do the actual allocation. The reason for doing it
1039 // before the allocation is that we avoid having to keep track of the newly
1040 // allocated memory while we do a GC.
1041 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1042 word_size)) {
1043 collect(GCCause::_g1_humongous_allocation);
1044 }
1045
1046 // We will loop until a) we manage to successfully perform the
1047 // allocation or b) we successfully schedule a collection which
1048 // fails to perform the allocation. b) is the only case when we'll
1049 // return NULL.
1050 HeapWord* result = NULL;
1051 for (int try_count = 1; /* we'll return */; try_count += 1) {
1052 bool should_try_gc;
1053 unsigned int gc_count_before;
1054
1055 {
1056 MutexLockerEx x(Heap_lock);
1057
1058 // Given that humongous objects are not allocated in young
1059 // regions, we'll first try to do the allocation without doing a
1060 // collection hoping that there's enough space in the heap.
1061 result = humongous_obj_allocate(word_size);
1062 if (result != NULL) {
1063 return result;
1064 }
1065
1066 if (GC_locker::is_active_and_needs_gc()) {
1067 should_try_gc = false;
1068 } else {
1069 // The GCLocker may not be active but the GCLocker initiated
1070 // GC may not yet have been performed (GCLocker::needs_gc()
1071 // returns true). In this case we do not try this GC and
1072 // wait until the GCLocker initiated GC is performed, and
1073 // then retry the allocation.
1074 if (GC_locker::needs_gc()) {
1075 should_try_gc = false;
1076 } else {
1077 // Read the GC count while still holding the Heap_lock.
1078 gc_count_before = total_collections();
1079 should_try_gc = true;
1080 }
1081 }
1082 }
1083
1084 if (should_try_gc) {
1085 // If we failed to allocate the humongous object, we should try to
1086 // do a collection pause (if we're allowed) in case it reclaims
1087 // enough space for the allocation to succeed after the pause.
1088
1089 bool succeeded;
1090 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1091 GCCause::_g1_humongous_allocation);
1092 if (result != NULL) {
1093 assert(succeeded, "only way to get back a non-NULL result");
1094 return result;
1095 }
1096
1097 if (succeeded) {
1098 // If we get here we successfully scheduled a collection which
1099 // failed to allocate. No point in trying to allocate
1100 // further. We'll just return NULL.
1101 MutexLockerEx x(Heap_lock);
1102 *gc_count_before_ret = total_collections();
1103 return NULL;
1104 }
1105 } else {
1106 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1107 MutexLockerEx x(Heap_lock);
1108 *gc_count_before_ret = total_collections();
1109 return NULL;
1110 }
1111 // The GCLocker is either active or the GCLocker initiated
1112 // GC has not yet been performed. Stall until it is and
1113 // then retry the allocation.
1114 GC_locker::stall_until_clear();
1115 (*gclocker_retry_count_ret) += 1;
1116 }
1117
1118 // We can reach here if we were unsuccessful in scheduling a
1119 // collection (because another thread beat us to it) or if we were
1120 // stalled due to the GC locker. In either can we should retry the
1121 // allocation attempt in case another thread successfully
1122 // performed a collection and reclaimed enough space. Give a
1123 // warning if we seem to be looping forever.
1124
1125 if ((QueuedAllocationWarningCount > 0) &&
1126 (try_count % QueuedAllocationWarningCount == 0)) {
1127 warning("G1CollectedHeap::attempt_allocation_humongous() "
1128 "retries %d times", try_count);
1129 }
1130 }
1131
1132 ShouldNotReachHere();
1133 return NULL;
1134 }
1135
1136 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1137 bool expect_null_mutator_alloc_region) {
1138 assert_at_safepoint(true /* should_be_vm_thread */);
1139 assert(_mutator_alloc_region.get() == NULL ||
1140 !expect_null_mutator_alloc_region,
1141 "the current alloc region was unexpectedly found to be non-NULL");
1142
1143 if (!isHumongous(word_size)) {
1144 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1145 false /* bot_updates */);
1146 } else {
1147 HeapWord* result = humongous_obj_allocate(word_size);
1148 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1149 g1_policy()->set_initiate_conc_mark_if_possible();
1150 }
1151 return result;
1152 }
1153
1154 ShouldNotReachHere();
1155 }
1156
1157 class PostMCRemSetClearClosure: public HeapRegionClosure {
1158 G1CollectedHeap* _g1h;
1159 ModRefBarrierSet* _mr_bs;
1160 public:
1161 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1162 _g1h(g1h), _mr_bs(mr_bs) {}
1163
1164 bool doHeapRegion(HeapRegion* r) {
1165 HeapRegionRemSet* hrrs = r->rem_set();
1166
1167 if (r->continuesHumongous()) {
1168 // We'll assert that the strong code root list and RSet is empty
1169 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1170 assert(hrrs->occupied() == 0, "RSet should be empty");
1171 return false;
1172 }
1173
1174 _g1h->reset_gc_time_stamps(r);
1175 hrrs->clear();
1176 // You might think here that we could clear just the cards
1177 // corresponding to the used region. But no: if we leave a dirty card
1178 // in a region we might allocate into, then it would prevent that card
1179 // from being enqueued, and cause it to be missed.
1180 // Re: the performance cost: we shouldn't be doing full GC anyway!
1181 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1182
1183 return false;
1184 }
1185 };
1186
1187 void G1CollectedHeap::clear_rsets_post_compaction() {
1188 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1189 heap_region_iterate(&rs_clear);
1190 }
1191
1192 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1193 G1CollectedHeap* _g1h;
1194 UpdateRSOopClosure _cl;
1195 int _worker_i;
1196 public:
1197 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1198 _cl(g1->g1_rem_set(), worker_i),
1199 _worker_i(worker_i),
1200 _g1h(g1)
1201 { }
1202
1203 bool doHeapRegion(HeapRegion* r) {
1204 if (!r->continuesHumongous()) {
1205 _cl.set_from(r);
1206 r->oop_iterate(&_cl);
1207 }
1208 return false;
1209 }
1210 };
1211
1212 class ParRebuildRSTask: public AbstractGangTask {
1213 G1CollectedHeap* _g1;
1214 public:
1215 ParRebuildRSTask(G1CollectedHeap* g1)
1216 : AbstractGangTask("ParRebuildRSTask"),
1217 _g1(g1)
1218 { }
1219
1220 void work(uint worker_id) {
1221 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1222 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1223 _g1->workers()->active_workers(),
1224 HeapRegion::RebuildRSClaimValue);
1225 }
1226 };
1227
1228 class PostCompactionPrinterClosure: public HeapRegionClosure {
1229 private:
1230 G1HRPrinter* _hr_printer;
1231 public:
1232 bool doHeapRegion(HeapRegion* hr) {
1233 assert(!hr->is_young(), "not expecting to find young regions");
1234 // We only generate output for non-empty regions.
1235 if (!hr->is_empty()) {
1236 if (!hr->isHumongous()) {
1237 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1238 } else if (hr->startsHumongous()) {
1239 if (hr->region_num() == 1) {
1240 // single humongous region
1241 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1242 } else {
1243 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1244 }
1245 } else {
1246 assert(hr->continuesHumongous(), "only way to get here");
1247 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1248 }
1249 }
1250 return false;
1251 }
1252
1253 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1254 : _hr_printer(hr_printer) { }
1255 };
1256
1257 void G1CollectedHeap::print_hrs_post_compaction() {
1258 PostCompactionPrinterClosure cl(hr_printer());
1259 heap_region_iterate(&cl);
1260 }
1261
1262 bool G1CollectedHeap::do_collection(bool explicit_gc,
1263 bool clear_all_soft_refs,
1264 size_t word_size) {
1265 assert_at_safepoint(true /* should_be_vm_thread */);
1266
1267 if (GC_locker::check_active_before_gc()) {
1268 return false;
1269 }
1270
1271 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1272 gc_timer->register_gc_start();
1273
1274 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1275 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1276
1277 SvcGCMarker sgcm(SvcGCMarker::FULL);
1278 ResourceMark rm;
1279
1280 print_heap_before_gc();
1281 trace_heap_before_gc(gc_tracer);
1282
1283 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1284
1285 verify_region_sets_optional();
1286
1287 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1288 collector_policy()->should_clear_all_soft_refs();
1289
1290 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1291
1292 {
1293 IsGCActiveMark x;
1294
1295 // Timing
1296 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1297 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1298 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1299
1300 {
1301 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1302 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1303 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1304
1305 double start = os::elapsedTime();
1306 g1_policy()->record_full_collection_start();
1307
1308 // Note: When we have a more flexible GC logging framework that
1309 // allows us to add optional attributes to a GC log record we
1310 // could consider timing and reporting how long we wait in the
1311 // following two methods.
1312 wait_while_free_regions_coming();
1313 // If we start the compaction before the CM threads finish
1314 // scanning the root regions we might trip them over as we'll
1315 // be moving objects / updating references. So let's wait until
1316 // they are done. By telling them to abort, they should complete
1317 // early.
1318 _cm->root_regions()->abort();
1319 _cm->root_regions()->wait_until_scan_finished();
1320 append_secondary_free_list_if_not_empty_with_lock();
1321
1322 gc_prologue(true);
1323 increment_total_collections(true /* full gc */);
1324 increment_old_marking_cycles_started();
1325
1326 assert(used() == recalculate_used(), "Should be equal");
1327
1328 verify_before_gc();
1329
1330 check_bitmaps("Full GC Start");
1331 pre_full_gc_dump(gc_timer);
1332
1333 COMPILER2_PRESENT(DerivedPointerTable::clear());
1334
1335 // Disable discovery and empty the discovered lists
1336 // for the CM ref processor.
1337 ref_processor_cm()->disable_discovery();
1338 ref_processor_cm()->abandon_partial_discovery();
1339 ref_processor_cm()->verify_no_references_recorded();
1340
1341 // Abandon current iterations of concurrent marking and concurrent
1342 // refinement, if any are in progress. We have to do this before
1343 // wait_until_scan_finished() below.
1344 concurrent_mark()->abort();
1345
1346 // Make sure we'll choose a new allocation region afterwards.
1347 release_mutator_alloc_region();
1348 abandon_gc_alloc_regions();
1349 g1_rem_set()->cleanupHRRS();
1350
1351 // We should call this after we retire any currently active alloc
1352 // regions so that all the ALLOC / RETIRE events are generated
1353 // before the start GC event.
1354 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1355
1356 // We may have added regions to the current incremental collection
1357 // set between the last GC or pause and now. We need to clear the
1358 // incremental collection set and then start rebuilding it afresh
1359 // after this full GC.
1360 abandon_collection_set(g1_policy()->inc_cset_head());
1361 g1_policy()->clear_incremental_cset();
1362 g1_policy()->stop_incremental_cset_building();
1363
1364 tear_down_region_sets(false /* free_list_only */);
1365 g1_policy()->set_gcs_are_young(true);
1366
1367 // See the comments in g1CollectedHeap.hpp and
1368 // G1CollectedHeap::ref_processing_init() about
1369 // how reference processing currently works in G1.
1370
1371 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1372 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1373
1374 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1375 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1376
1377 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1378 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1379
1380 // Do collection work
1381 {
1382 HandleMark hm; // Discard invalid handles created during gc
1383 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1384 }
1385
1386 assert(free_regions() == 0, "we should not have added any free regions");
1387 rebuild_region_sets(false /* free_list_only */);
1388
1389 // Enqueue any discovered reference objects that have
1390 // not been removed from the discovered lists.
1391 ref_processor_stw()->enqueue_discovered_references();
1392
1393 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1394
1395 MemoryService::track_memory_usage();
1396
1397 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1398 ref_processor_stw()->verify_no_references_recorded();
1399
1400 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1401 ClassLoaderDataGraph::purge();
1402 MetaspaceAux::verify_metrics();
1403
1404 // Note: since we've just done a full GC, concurrent
1405 // marking is no longer active. Therefore we need not
1406 // re-enable reference discovery for the CM ref processor.
1407 // That will be done at the start of the next marking cycle.
1408 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1409 ref_processor_cm()->verify_no_references_recorded();
1410
1411 reset_gc_time_stamp();
1412 // Since everything potentially moved, we will clear all remembered
1413 // sets, and clear all cards. Later we will rebuild remembered
1414 // sets. We will also reset the GC time stamps of the regions.
1415 clear_rsets_post_compaction();
1416 check_gc_time_stamps();
1417
1418 // Resize the heap if necessary.
1419 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1420
1421 if (_hr_printer.is_active()) {
1422 // We should do this after we potentially resize the heap so
1423 // that all the COMMIT / UNCOMMIT events are generated before
1424 // the end GC event.
1425
1426 print_hrs_post_compaction();
1427 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1428 }
1429
1430 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1431 if (hot_card_cache->use_cache()) {
1432 hot_card_cache->reset_card_counts();
1433 hot_card_cache->reset_hot_cache();
1434 }
1435
1436 // Rebuild remembered sets of all regions.
1437 if (G1CollectedHeap::use_parallel_gc_threads()) {
1438 uint n_workers =
1439 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1440 workers()->active_workers(),
1441 Threads::number_of_non_daemon_threads());
1442 assert(UseDynamicNumberOfGCThreads ||
1443 n_workers == workers()->total_workers(),
1444 "If not dynamic should be using all the workers");
1445 workers()->set_active_workers(n_workers);
1446 // Set parallel threads in the heap (_n_par_threads) only
1447 // before a parallel phase and always reset it to 0 after
1448 // the phase so that the number of parallel threads does
1449 // no get carried forward to a serial phase where there
1450 // may be code that is "possibly_parallel".
1451 set_par_threads(n_workers);
1452
1453 ParRebuildRSTask rebuild_rs_task(this);
1454 assert(check_heap_region_claim_values(
1455 HeapRegion::InitialClaimValue), "sanity check");
1456 assert(UseDynamicNumberOfGCThreads ||
1457 workers()->active_workers() == workers()->total_workers(),
1458 "Unless dynamic should use total workers");
1459 // Use the most recent number of active workers
1460 assert(workers()->active_workers() > 0,
1461 "Active workers not properly set");
1462 set_par_threads(workers()->active_workers());
1463 workers()->run_task(&rebuild_rs_task);
1464 set_par_threads(0);
1465 assert(check_heap_region_claim_values(
1466 HeapRegion::RebuildRSClaimValue), "sanity check");
1467 reset_heap_region_claim_values();
1468 } else {
1469 RebuildRSOutOfRegionClosure rebuild_rs(this);
1470 heap_region_iterate(&rebuild_rs);
1471 }
1472
1473 // Rebuild the strong code root lists for each region
1474 rebuild_strong_code_roots();
1475
1476 if (true) { // FIXME
1477 MetaspaceGC::compute_new_size();
1478 }
1479
1480 #ifdef TRACESPINNING
1481 ParallelTaskTerminator::print_termination_counts();
1482 #endif
1483
1484 // Discard all rset updates
1485 JavaThread::dirty_card_queue_set().abandon_logs();
1486 assert(!G1DeferredRSUpdate
1487 || (G1DeferredRSUpdate &&
1488 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1489
1490 _young_list->reset_sampled_info();
1491 // At this point there should be no regions in the
1492 // entire heap tagged as young.
1493 assert(check_young_list_empty(true /* check_heap */),
1494 "young list should be empty at this point");
1495
1496 // Update the number of full collections that have been completed.
1497 increment_old_marking_cycles_completed(false /* concurrent */);
1498
1499 _hrs.verify_optional();
1500 verify_region_sets_optional();
1501
1502 verify_after_gc();
1503
1504 // Clear the previous marking bitmap, if needed for bitmap verification.
1505 // Note we cannot do this when we clear the next marking bitmap in
1506 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1507 // objects marked during a full GC against the previous bitmap.
1508 // But we need to clear it before calling check_bitmaps below since
1509 // the full GC has compacted objects and updated TAMS but not updated
1510 // the prev bitmap.
1511 if (G1VerifyBitmaps) {
1512 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1513 }
1514 check_bitmaps("Full GC End");
1515
1516 // Start a new incremental collection set for the next pause
1517 assert(g1_policy()->collection_set() == NULL, "must be");
1518 g1_policy()->start_incremental_cset_building();
1519
1520 clear_cset_fast_test();
1521
1522 init_mutator_alloc_region();
1523
1524 double end = os::elapsedTime();
1525 g1_policy()->record_full_collection_end();
1526
1527 if (G1Log::fine()) {
1528 g1_policy()->print_heap_transition();
1529 }
1530
1531 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1532 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1533 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1534 // before any GC notifications are raised.
1535 g1mm()->update_sizes();
1536
1537 gc_epilogue(true);
1538 }
1539
1540 if (G1Log::finer()) {
1541 g1_policy()->print_detailed_heap_transition(true /* full */);
1542 }
1543
1544 print_heap_after_gc();
1545 trace_heap_after_gc(gc_tracer);
1546
1547 post_full_gc_dump(gc_timer);
1548
1549 gc_timer->register_gc_end();
1550 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1551 }
1552
1553 return true;
1554 }
1555
1556 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1557 // do_collection() will return whether it succeeded in performing
1558 // the GC. Currently, there is no facility on the
1559 // do_full_collection() API to notify the caller than the collection
1560 // did not succeed (e.g., because it was locked out by the GC
1561 // locker). So, right now, we'll ignore the return value.
1562 bool dummy = do_collection(true, /* explicit_gc */
1563 clear_all_soft_refs,
1564 0 /* word_size */);
1565 }
1566
1567 // This code is mostly copied from TenuredGeneration.
1568 void
1569 G1CollectedHeap::
1570 resize_if_necessary_after_full_collection(size_t word_size) {
1571 // Include the current allocation, if any, and bytes that will be
1572 // pre-allocated to support collections, as "used".
1573 const size_t used_after_gc = used();
1574 const size_t capacity_after_gc = capacity();
1575 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1576
1577 // This is enforced in arguments.cpp.
1578 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1579 "otherwise the code below doesn't make sense");
1580
1581 // We don't have floating point command-line arguments
1582 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1583 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1584 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1585 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1586
1587 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1588 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1589
1590 // We have to be careful here as these two calculations can overflow
1591 // 32-bit size_t's.
1592 double used_after_gc_d = (double) used_after_gc;
1593 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1594 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1595
1596 // Let's make sure that they are both under the max heap size, which
1597 // by default will make them fit into a size_t.
1598 double desired_capacity_upper_bound = (double) max_heap_size;
1599 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1600 desired_capacity_upper_bound);
1601 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1602 desired_capacity_upper_bound);
1603
1604 // We can now safely turn them into size_t's.
1605 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1606 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1607
1608 // This assert only makes sense here, before we adjust them
1609 // with respect to the min and max heap size.
1610 assert(minimum_desired_capacity <= maximum_desired_capacity,
1611 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1612 "maximum_desired_capacity = "SIZE_FORMAT,
1613 minimum_desired_capacity, maximum_desired_capacity));
1614
1615 // Should not be greater than the heap max size. No need to adjust
1616 // it with respect to the heap min size as it's a lower bound (i.e.,
1617 // we'll try to make the capacity larger than it, not smaller).
1618 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1619 // Should not be less than the heap min size. No need to adjust it
1620 // with respect to the heap max size as it's an upper bound (i.e.,
1621 // we'll try to make the capacity smaller than it, not greater).
1622 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1623
1624 if (capacity_after_gc < minimum_desired_capacity) {
1625 // Don't expand unless it's significant
1626 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1627 ergo_verbose4(ErgoHeapSizing,
1628 "attempt heap expansion",
1629 ergo_format_reason("capacity lower than "
1630 "min desired capacity after Full GC")
1631 ergo_format_byte("capacity")
1632 ergo_format_byte("occupancy")
1633 ergo_format_byte_perc("min desired capacity"),
1634 capacity_after_gc, used_after_gc,
1635 minimum_desired_capacity, (double) MinHeapFreeRatio);
1636 expand(expand_bytes);
1637
1638 // No expansion, now see if we want to shrink
1639 } else if (capacity_after_gc > maximum_desired_capacity) {
1640 // Capacity too large, compute shrinking size
1641 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1642 ergo_verbose4(ErgoHeapSizing,
1643 "attempt heap shrinking",
1644 ergo_format_reason("capacity higher than "
1645 "max desired capacity after Full GC")
1646 ergo_format_byte("capacity")
1647 ergo_format_byte("occupancy")
1648 ergo_format_byte_perc("max desired capacity"),
1649 capacity_after_gc, used_after_gc,
1650 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1651 shrink(shrink_bytes);
1652 }
1653 }
1654
1655
1656 HeapWord*
1657 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1658 bool* succeeded) {
1659 assert_at_safepoint(true /* should_be_vm_thread */);
1660
1661 *succeeded = true;
1662 // Let's attempt the allocation first.
1663 HeapWord* result =
1664 attempt_allocation_at_safepoint(word_size,
1665 false /* expect_null_mutator_alloc_region */);
1666 if (result != NULL) {
1667 assert(*succeeded, "sanity");
1668 return result;
1669 }
1670
1671 // In a G1 heap, we're supposed to keep allocation from failing by
1672 // incremental pauses. Therefore, at least for now, we'll favor
1673 // expansion over collection. (This might change in the future if we can
1674 // do something smarter than full collection to satisfy a failed alloc.)
1675 result = expand_and_allocate(word_size);
1676 if (result != NULL) {
1677 assert(*succeeded, "sanity");
1678 return result;
1679 }
1680
1681 // Expansion didn't work, we'll try to do a Full GC.
1682 bool gc_succeeded = do_collection(false, /* explicit_gc */
1683 false, /* clear_all_soft_refs */
1684 word_size);
1685 if (!gc_succeeded) {
1686 *succeeded = false;
1687 return NULL;
1688 }
1689
1690 // Retry the allocation
1691 result = attempt_allocation_at_safepoint(word_size,
1692 true /* expect_null_mutator_alloc_region */);
1693 if (result != NULL) {
1694 assert(*succeeded, "sanity");
1695 return result;
1696 }
1697
1698 // Then, try a Full GC that will collect all soft references.
1699 gc_succeeded = do_collection(false, /* explicit_gc */
1700 true, /* clear_all_soft_refs */
1701 word_size);
1702 if (!gc_succeeded) {
1703 *succeeded = false;
1704 return NULL;
1705 }
1706
1707 // Retry the allocation once more
1708 result = attempt_allocation_at_safepoint(word_size,
1709 true /* expect_null_mutator_alloc_region */);
1710 if (result != NULL) {
1711 assert(*succeeded, "sanity");
1712 return result;
1713 }
1714
1715 assert(!collector_policy()->should_clear_all_soft_refs(),
1716 "Flag should have been handled and cleared prior to this point");
1717
1718 // What else? We might try synchronous finalization later. If the total
1719 // space available is large enough for the allocation, then a more
1720 // complete compaction phase than we've tried so far might be
1721 // appropriate.
1722 assert(*succeeded, "sanity");
1723 return NULL;
1724 }
1725
1726 // Attempting to expand the heap sufficiently
1727 // to support an allocation of the given "word_size". If
1728 // successful, perform the allocation and return the address of the
1729 // allocated block, or else "NULL".
1730
1731 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1732 assert_at_safepoint(true /* should_be_vm_thread */);
1733
1734 verify_region_sets_optional();
1735
1736 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1737 ergo_verbose1(ErgoHeapSizing,
1738 "attempt heap expansion",
1739 ergo_format_reason("allocation request failed")
1740 ergo_format_byte("allocation request"),
1741 word_size * HeapWordSize);
1742 if (expand(expand_bytes)) {
1743 _hrs.verify_optional();
1744 verify_region_sets_optional();
1745 return attempt_allocation_at_safepoint(word_size,
1746 false /* expect_null_mutator_alloc_region */);
1747 }
1748 return NULL;
1749 }
1750
1751 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1752 HeapWord* new_end) {
1753 assert(old_end != new_end, "don't call this otherwise");
1754 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1755
1756 // Update the committed mem region.
1757 _g1_committed.set_end(new_end);
1758 // Tell the card table about the update.
1759 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1760 // Tell the BOT about the update.
1761 _bot_shared->resize(_g1_committed.word_size());
1762 // Tell the hot card cache about the update
1763 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1764 }
1765
1766 bool G1CollectedHeap::expand(size_t expand_bytes) {
1767 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1768 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1769 HeapRegion::GrainBytes);
1770 ergo_verbose2(ErgoHeapSizing,
1771 "expand the heap",
1772 ergo_format_byte("requested expansion amount")
1773 ergo_format_byte("attempted expansion amount"),
1774 expand_bytes, aligned_expand_bytes);
1775
1776 if (_g1_storage.uncommitted_size() == 0) {
1777 ergo_verbose0(ErgoHeapSizing,
1778 "did not expand the heap",
1779 ergo_format_reason("heap already fully expanded"));
1780 return false;
1781 }
1782
1783 // First commit the memory.
1784 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1785 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1786 if (successful) {
1787 // Then propagate this update to the necessary data structures.
1788 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1789 update_committed_space(old_end, new_end);
1790
1791 FreeRegionList expansion_list("Local Expansion List");
1792 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1793 assert(mr.start() == old_end, "post-condition");
1794 // mr might be a smaller region than what was requested if
1795 // expand_by() was unable to allocate the HeapRegion instances
1796 assert(mr.end() <= new_end, "post-condition");
1797
1798 size_t actual_expand_bytes = mr.byte_size();
1799 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1800 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1801 "post-condition");
1802 if (actual_expand_bytes < aligned_expand_bytes) {
1803 // We could not expand _hrs to the desired size. In this case we
1804 // need to shrink the committed space accordingly.
1805 assert(mr.end() < new_end, "invariant");
1806
1807 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1808 // First uncommit the memory.
1809 _g1_storage.shrink_by(diff_bytes);
1810 // Then propagate this update to the necessary data structures.
1811 update_committed_space(new_end, mr.end());
1812 }
1813 _free_list.add_as_tail(&expansion_list);
1814
1815 if (_hr_printer.is_active()) {
1816 HeapWord* curr = mr.start();
1817 while (curr < mr.end()) {
1818 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1819 _hr_printer.commit(curr, curr_end);
1820 curr = curr_end;
1821 }
1822 assert(curr == mr.end(), "post-condition");
1823 }
1824 g1_policy()->record_new_heap_size(n_regions());
1825 } else {
1826 ergo_verbose0(ErgoHeapSizing,
1827 "did not expand the heap",
1828 ergo_format_reason("heap expansion operation failed"));
1829 // The expansion of the virtual storage space was unsuccessful.
1830 // Let's see if it was because we ran out of swap.
1831 if (G1ExitOnExpansionFailure &&
1832 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1833 // We had head room...
1834 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1835 }
1836 }
1837 return successful;
1838 }
1839
1840 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1841 size_t aligned_shrink_bytes =
1842 ReservedSpace::page_align_size_down(shrink_bytes);
1843 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1844 HeapRegion::GrainBytes);
1845 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1846
1847 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1848 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1849 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1850
1851 ergo_verbose3(ErgoHeapSizing,
1852 "shrink the heap",
1853 ergo_format_byte("requested shrinking amount")
1854 ergo_format_byte("aligned shrinking amount")
1855 ergo_format_byte("attempted shrinking amount"),
1856 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1857 if (num_regions_removed > 0) {
1858 _g1_storage.shrink_by(shrunk_bytes);
1859 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1860
1861 if (_hr_printer.is_active()) {
1862 HeapWord* curr = old_end;
1863 while (curr > new_end) {
1864 HeapWord* curr_end = curr;
1865 curr -= HeapRegion::GrainWords;
1866 _hr_printer.uncommit(curr, curr_end);
1867 }
1868 }
1869
1870 _expansion_regions += num_regions_removed;
1871 update_committed_space(old_end, new_end);
1872 HeapRegionRemSet::shrink_heap(n_regions());
1873 g1_policy()->record_new_heap_size(n_regions());
1874 } else {
1875 ergo_verbose0(ErgoHeapSizing,
1876 "did not shrink the heap",
1877 ergo_format_reason("heap shrinking operation failed"));
1878 }
1879 }
1880
1881 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1882 verify_region_sets_optional();
1883
1884 // We should only reach here at the end of a Full GC which means we
1885 // should not not be holding to any GC alloc regions. The method
1886 // below will make sure of that and do any remaining clean up.
1887 abandon_gc_alloc_regions();
1888
1889 // Instead of tearing down / rebuilding the free lists here, we
1890 // could instead use the remove_all_pending() method on free_list to
1891 // remove only the ones that we need to remove.
1892 tear_down_region_sets(true /* free_list_only */);
1893 shrink_helper(shrink_bytes);
1894 rebuild_region_sets(true /* free_list_only */);
1895
1896 _hrs.verify_optional();
1897 verify_region_sets_optional();
1898 }
1899
1900 // Public methods.
1901
1902 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1903 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1904 #endif // _MSC_VER
1905
1906
1907 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1908 SharedHeap(policy_),
1909 _g1_policy(policy_),
1910 _dirty_card_queue_set(false),
1911 _into_cset_dirty_card_queue_set(false),
1912 _is_alive_closure_cm(this),
1913 _is_alive_closure_stw(this),
1914 _ref_processor_cm(NULL),
1915 _ref_processor_stw(NULL),
1916 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1917 _bot_shared(NULL),
1918 _evac_failure_scan_stack(NULL),
1919 _mark_in_progress(false),
1920 _cg1r(NULL), _summary_bytes_used(0),
1921 _g1mm(NULL),
1922 _refine_cte_cl(NULL),
1923 _full_collection(false),
1924 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1925 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1926 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1927 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1928 _free_regions_coming(false),
1929 _young_list(new YoungList(this)),
1930 _gc_time_stamp(0),
1931 _retained_old_gc_alloc_region(NULL),
1932 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1933 _old_plab_stats(OldPLABSize, PLABWeight),
1934 _expand_heap_after_alloc_failure(true),
1935 _surviving_young_words(NULL),
1936 _old_marking_cycles_started(0),
1937 _old_marking_cycles_completed(0),
1938 _concurrent_cycle_started(false),
1939 _in_cset_fast_test(),
1940 _dirty_cards_region_list(NULL),
1941 _worker_cset_start_region(NULL),
1942 _worker_cset_start_region_time_stamp(NULL),
1943 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1944 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1945 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1946 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1947
1948 _g1h = this;
1949 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1950 vm_exit_during_initialization("Failed necessary allocation.");
1951 }
1952
1953 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1954
1955 int n_queues = MAX2((int)ParallelGCThreads, 1);
1956 _task_queues = new RefToScanQueueSet(n_queues);
1957
1958 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1959 assert(n_rem_sets > 0, "Invariant.");
1960
1961 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1962 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1963 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1964
1965 for (int i = 0; i < n_queues; i++) {
1966 RefToScanQueue* q = new RefToScanQueue();
1967 q->initialize();
1968 _task_queues->register_queue(i, q);
1969 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1970 }
1971 clear_cset_start_regions();
1972
1973 // Initialize the G1EvacuationFailureALot counters and flags.
1974 NOT_PRODUCT(reset_evacuation_should_fail();)
1975
1976 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1977 }
1978
1979 jint G1CollectedHeap::initialize() {
1980 CollectedHeap::pre_initialize();
1981 os::enable_vtime();
1982
1983 G1Log::init();
1984
1985 // Necessary to satisfy locking discipline assertions.
1986
1987 MutexLocker x(Heap_lock);
1988
1989 // We have to initialize the printer before committing the heap, as
1990 // it will be used then.
1991 _hr_printer.set_active(G1PrintHeapRegions);
1992
1993 // While there are no constraints in the GC code that HeapWordSize
1994 // be any particular value, there are multiple other areas in the
1995 // system which believe this to be true (e.g. oop->object_size in some
1996 // cases incorrectly returns the size in wordSize units rather than
1997 // HeapWordSize).
1998 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1999
2000 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2001 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2002 size_t heap_alignment = collector_policy()->heap_alignment();
2003
2004 // Ensure that the sizes are properly aligned.
2005 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2006 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2007 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2008
2009 _refine_cte_cl = new RefineCardTableEntryClosure();
2010
2011 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2012
2013 // Reserve the maximum.
2014
2015 // When compressed oops are enabled, the preferred heap base
2016 // is calculated by subtracting the requested size from the
2017 // 32Gb boundary and using the result as the base address for
2018 // heap reservation. If the requested size is not aligned to
2019 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2020 // into the ReservedHeapSpace constructor) then the actual
2021 // base of the reserved heap may end up differing from the
2022 // address that was requested (i.e. the preferred heap base).
2023 // If this happens then we could end up using a non-optimal
2024 // compressed oops mode.
2025
2026 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2027 heap_alignment);
2028
2029 // It is important to do this in a way such that concurrent readers can't
2030 // temporarily think something is in the heap. (I've actually seen this
2031 // happen in asserts: DLD.)
2032 _reserved.set_word_size(0);
2033 _reserved.set_start((HeapWord*)heap_rs.base());
2034 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2035
2036 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2037
2038 // Create the gen rem set (and barrier set) for the entire reserved region.
2039 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2040 set_barrier_set(rem_set()->bs());
2041 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2042 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2043 return JNI_ENOMEM;
2044 }
2045
2046 // Also create a G1 rem set.
2047 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2048
2049 // Carve out the G1 part of the heap.
2050
2051 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2052 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2053 g1_rs.size()/HeapWordSize);
2054
2055 _g1_storage.initialize(g1_rs, 0);
2056 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2057 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2058 (HeapWord*) _g1_reserved.end());
2059 assert(_hrs.max_length() == _expansion_regions,
2060 err_msg("max length: %u expansion regions: %u",
2061 _hrs.max_length(), _expansion_regions));
2062
2063 // Do later initialization work for concurrent refinement.
2064 _cg1r->init();
2065
2066 // 6843694 - ensure that the maximum region index can fit
2067 // in the remembered set structures.
2068 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2069 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2070
2071 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2072 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2073 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2074 "too many cards per region");
2075
2076 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2077
2078 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2079 heap_word_size(init_byte_size));
2080
2081 _g1h = this;
2082
2083 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2084
2085 // Create the ConcurrentMark data structure and thread.
2086 // (Must do this late, so that "max_regions" is defined.)
2087 _cm = new ConcurrentMark(this, heap_rs);
2088 if (_cm == NULL || !_cm->completed_initialization()) {
2089 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2090 return JNI_ENOMEM;
2091 }
2092 _cmThread = _cm->cmThread();
2093
2094 // Initialize the from_card cache structure of HeapRegionRemSet.
2095 HeapRegionRemSet::init_heap(max_regions());
2096
2097 // Now expand into the initial heap size.
2098 if (!expand(init_byte_size)) {
2099 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2100 return JNI_ENOMEM;
2101 }
2102
2103 // Perform any initialization actions delegated to the policy.
2104 g1_policy()->init();
2105
2106 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2107 SATB_Q_FL_lock,
2108 G1SATBProcessCompletedThreshold,
2109 Shared_SATB_Q_lock);
2110
2111 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2112 DirtyCardQ_CBL_mon,
2113 DirtyCardQ_FL_lock,
2114 concurrent_g1_refine()->yellow_zone(),
2115 concurrent_g1_refine()->red_zone(),
2116 Shared_DirtyCardQ_lock);
2117
2118 if (G1DeferredRSUpdate) {
2119 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2120 DirtyCardQ_CBL_mon,
2121 DirtyCardQ_FL_lock,
2122 -1, // never trigger processing
2123 -1, // no limit on length
2124 Shared_DirtyCardQ_lock,
2125 &JavaThread::dirty_card_queue_set());
2126 }
2127
2128 // Initialize the card queue set used to hold cards containing
2129 // references into the collection set.
2130 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2131 DirtyCardQ_CBL_mon,
2132 DirtyCardQ_FL_lock,
2133 -1, // never trigger processing
2134 -1, // no limit on length
2135 Shared_DirtyCardQ_lock,
2136 &JavaThread::dirty_card_queue_set());
2137
2138 // In case we're keeping closure specialization stats, initialize those
2139 // counts and that mechanism.
2140 SpecializationStats::clear();
2141
2142 // Here we allocate the dummy full region that is required by the
2143 // G1AllocRegion class. If we don't pass an address in the reserved
2144 // space here, lots of asserts fire.
2145
2146 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2147 _g1_reserved.start());
2148 // We'll re-use the same region whether the alloc region will
2149 // require BOT updates or not and, if it doesn't, then a non-young
2150 // region will complain that it cannot support allocations without
2151 // BOT updates. So we'll tag the dummy region as young to avoid that.
2152 dummy_region->set_young();
2153 // Make sure it's full.
2154 dummy_region->set_top(dummy_region->end());
2155 G1AllocRegion::setup(this, dummy_region);
2156
2157 init_mutator_alloc_region();
2158
2159 // Do create of the monitoring and management support so that
2160 // values in the heap have been properly initialized.
2161 _g1mm = new G1MonitoringSupport(this);
2162
2163 G1StringDedup::initialize();
2164
2165 return JNI_OK;
2166 }
2167
2168 void G1CollectedHeap::stop() {
2169 #if 0
2170 // Stopping concurrent worker threads is currently disabled until
2171 // some bugs in concurrent mark has been resolve. Without fixing
2172 // those bugs first we risk haning during VM exit when trying to
2173 // stop these threads.
2174
2175 // Abort any ongoing concurrent root region scanning and stop all
2176 // concurrent threads. We do this to make sure these threads do
2177 // not continue to execute and access resources (e.g. gclog_or_tty)
2178 // that are destroyed during shutdown.
2179 _cm->root_regions()->abort();
2180 _cm->root_regions()->wait_until_scan_finished();
2181 stop_conc_gc_threads();
2182 #endif
2183 }
2184
2185 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2186 return HeapRegion::max_region_size();
2187 }
2188
2189 void G1CollectedHeap::ref_processing_init() {
2190 // Reference processing in G1 currently works as follows:
2191 //
2192 // * There are two reference processor instances. One is
2193 // used to record and process discovered references
2194 // during concurrent marking; the other is used to
2195 // record and process references during STW pauses
2196 // (both full and incremental).
2197 // * Both ref processors need to 'span' the entire heap as
2198 // the regions in the collection set may be dotted around.
2199 //
2200 // * For the concurrent marking ref processor:
2201 // * Reference discovery is enabled at initial marking.
2202 // * Reference discovery is disabled and the discovered
2203 // references processed etc during remarking.
2204 // * Reference discovery is MT (see below).
2205 // * Reference discovery requires a barrier (see below).
2206 // * Reference processing may or may not be MT
2207 // (depending on the value of ParallelRefProcEnabled
2208 // and ParallelGCThreads).
2209 // * A full GC disables reference discovery by the CM
2210 // ref processor and abandons any entries on it's
2211 // discovered lists.
2212 //
2213 // * For the STW processor:
2214 // * Non MT discovery is enabled at the start of a full GC.
2215 // * Processing and enqueueing during a full GC is non-MT.
2216 // * During a full GC, references are processed after marking.
2217 //
2218 // * Discovery (may or may not be MT) is enabled at the start
2219 // of an incremental evacuation pause.
2220 // * References are processed near the end of a STW evacuation pause.
2221 // * For both types of GC:
2222 // * Discovery is atomic - i.e. not concurrent.
2223 // * Reference discovery will not need a barrier.
2224
2225 SharedHeap::ref_processing_init();
2226 MemRegion mr = reserved_region();
2227
2228 // Concurrent Mark ref processor
2229 _ref_processor_cm =
2230 new ReferenceProcessor(mr, // span
2231 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2232 // mt processing
2233 (int) ParallelGCThreads,
2234 // degree of mt processing
2235 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2236 // mt discovery
2237 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2238 // degree of mt discovery
2239 false,
2240 // Reference discovery is not atomic
2241 &_is_alive_closure_cm,
2242 // is alive closure
2243 // (for efficiency/performance)
2244 true);
2245 // Setting next fields of discovered
2246 // lists requires a barrier.
2247
2248 // STW ref processor
2249 _ref_processor_stw =
2250 new ReferenceProcessor(mr, // span
2251 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2252 // mt processing
2253 MAX2((int)ParallelGCThreads, 1),
2254 // degree of mt processing
2255 (ParallelGCThreads > 1),
2256 // mt discovery
2257 MAX2((int)ParallelGCThreads, 1),
2258 // degree of mt discovery
2259 true,
2260 // Reference discovery is atomic
2261 &_is_alive_closure_stw,
2262 // is alive closure
2263 // (for efficiency/performance)
2264 false);
2265 // Setting next fields of discovered
2266 // lists does not require a barrier.
2267 }
2268
2269 size_t G1CollectedHeap::capacity() const {
2270 return _g1_committed.byte_size();
2271 }
2272
2273 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2274 assert(!hr->continuesHumongous(), "pre-condition");
2275 hr->reset_gc_time_stamp();
2276 if (hr->startsHumongous()) {
2277 uint first_index = hr->hrs_index() + 1;
2278 uint last_index = hr->last_hc_index();
2279 for (uint i = first_index; i < last_index; i += 1) {
2280 HeapRegion* chr = region_at(i);
2281 assert(chr->continuesHumongous(), "sanity");
2282 chr->reset_gc_time_stamp();
2283 }
2284 }
2285 }
2286
2287 #ifndef PRODUCT
2288 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2289 private:
2290 unsigned _gc_time_stamp;
2291 bool _failures;
2292
2293 public:
2294 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2295 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2296
2297 virtual bool doHeapRegion(HeapRegion* hr) {
2298 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2299 if (_gc_time_stamp != region_gc_time_stamp) {
2300 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2301 "expected %d", HR_FORMAT_PARAMS(hr),
2302 region_gc_time_stamp, _gc_time_stamp);
2303 _failures = true;
2304 }
2305 return false;
2306 }
2307
2308 bool failures() { return _failures; }
2309 };
2310
2311 void G1CollectedHeap::check_gc_time_stamps() {
2312 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2313 heap_region_iterate(&cl);
2314 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2315 }
2316 #endif // PRODUCT
2317
2318 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2319 DirtyCardQueue* into_cset_dcq,
2320 bool concurrent,
2321 uint worker_i) {
2322 // Clean cards in the hot card cache
2323 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2324 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2325
2326 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2327 int n_completed_buffers = 0;
2328 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2329 n_completed_buffers++;
2330 }
2331 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2332 dcqs.clear_n_completed_buffers();
2333 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2334 }
2335
2336
2337 // Computes the sum of the storage used by the various regions.
2338
2339 size_t G1CollectedHeap::used() const {
2340 assert(Heap_lock->owner() != NULL,
2341 "Should be owned on this thread's behalf.");
2342 size_t result = _summary_bytes_used;
2343 // Read only once in case it is set to NULL concurrently
2344 HeapRegion* hr = _mutator_alloc_region.get();
2345 if (hr != NULL)
2346 result += hr->used();
2347 return result;
2348 }
2349
2350 size_t G1CollectedHeap::used_unlocked() const {
2351 size_t result = _summary_bytes_used;
2352 return result;
2353 }
2354
2355 class SumUsedClosure: public HeapRegionClosure {
2356 size_t _used;
2357 public:
2358 SumUsedClosure() : _used(0) {}
2359 bool doHeapRegion(HeapRegion* r) {
2360 if (!r->continuesHumongous()) {
2361 _used += r->used();
2362 }
2363 return false;
2364 }
2365 size_t result() { return _used; }
2366 };
2367
2368 size_t G1CollectedHeap::recalculate_used() const {
2369 double recalculate_used_start = os::elapsedTime();
2370
2371 SumUsedClosure blk;
2372 heap_region_iterate(&blk);
2373
2374 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2375 return blk.result();
2376 }
2377
2378 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2379 switch (cause) {
2380 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2381 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2382 case GCCause::_g1_humongous_allocation: return true;
2383 default: return false;
2384 }
2385 }
2386
2387 #ifndef PRODUCT
2388 void G1CollectedHeap::allocate_dummy_regions() {
2389 // Let's fill up most of the region
2390 size_t word_size = HeapRegion::GrainWords - 1024;
2391 // And as a result the region we'll allocate will be humongous.
2392 guarantee(isHumongous(word_size), "sanity");
2393
2394 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2395 // Let's use the existing mechanism for the allocation
2396 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2397 if (dummy_obj != NULL) {
2398 MemRegion mr(dummy_obj, word_size);
2399 CollectedHeap::fill_with_object(mr);
2400 } else {
2401 // If we can't allocate once, we probably cannot allocate
2402 // again. Let's get out of the loop.
2403 break;
2404 }
2405 }
2406 }
2407 #endif // !PRODUCT
2408
2409 void G1CollectedHeap::increment_old_marking_cycles_started() {
2410 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2411 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2412 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2413 _old_marking_cycles_started, _old_marking_cycles_completed));
2414
2415 _old_marking_cycles_started++;
2416 }
2417
2418 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2419 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2420
2421 // We assume that if concurrent == true, then the caller is a
2422 // concurrent thread that was joined the Suspendible Thread
2423 // Set. If there's ever a cheap way to check this, we should add an
2424 // assert here.
2425
2426 // Given that this method is called at the end of a Full GC or of a
2427 // concurrent cycle, and those can be nested (i.e., a Full GC can
2428 // interrupt a concurrent cycle), the number of full collections
2429 // completed should be either one (in the case where there was no
2430 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2431 // behind the number of full collections started.
2432
2433 // This is the case for the inner caller, i.e. a Full GC.
2434 assert(concurrent ||
2435 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2436 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2437 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2438 "is inconsistent with _old_marking_cycles_completed = %u",
2439 _old_marking_cycles_started, _old_marking_cycles_completed));
2440
2441 // This is the case for the outer caller, i.e. the concurrent cycle.
2442 assert(!concurrent ||
2443 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2444 err_msg("for outer caller (concurrent cycle): "
2445 "_old_marking_cycles_started = %u "
2446 "is inconsistent with _old_marking_cycles_completed = %u",
2447 _old_marking_cycles_started, _old_marking_cycles_completed));
2448
2449 _old_marking_cycles_completed += 1;
2450
2451 // We need to clear the "in_progress" flag in the CM thread before
2452 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2453 // is set) so that if a waiter requests another System.gc() it doesn't
2454 // incorrectly see that a marking cycle is still in progress.
2455 if (concurrent) {
2456 _cmThread->clear_in_progress();
2457 }
2458
2459 // This notify_all() will ensure that a thread that called
2460 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2461 // and it's waiting for a full GC to finish will be woken up. It is
2462 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2463 FullGCCount_lock->notify_all();
2464 }
2465
2466 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2467 _concurrent_cycle_started = true;
2468 _gc_timer_cm->register_gc_start(start_time);
2469
2470 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2471 trace_heap_before_gc(_gc_tracer_cm);
2472 }
2473
2474 void G1CollectedHeap::register_concurrent_cycle_end() {
2475 if (_concurrent_cycle_started) {
2476 if (_cm->has_aborted()) {
2477 _gc_tracer_cm->report_concurrent_mode_failure();
2478 }
2479
2480 _gc_timer_cm->register_gc_end();
2481 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2482
2483 _concurrent_cycle_started = false;
2484 }
2485 }
2486
2487 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2488 if (_concurrent_cycle_started) {
2489 trace_heap_after_gc(_gc_tracer_cm);
2490 }
2491 }
2492
2493 G1YCType G1CollectedHeap::yc_type() {
2494 bool is_young = g1_policy()->gcs_are_young();
2495 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2496 bool is_during_mark = mark_in_progress();
2497
2498 if (is_initial_mark) {
2499 return InitialMark;
2500 } else if (is_during_mark) {
2501 return DuringMark;
2502 } else if (is_young) {
2503 return Normal;
2504 } else {
2505 return Mixed;
2506 }
2507 }
2508
2509 void G1CollectedHeap::collect(GCCause::Cause cause) {
2510 assert_heap_not_locked();
2511
2512 unsigned int gc_count_before;
2513 unsigned int old_marking_count_before;
2514 bool retry_gc;
2515
2516 do {
2517 retry_gc = false;
2518
2519 {
2520 MutexLocker ml(Heap_lock);
2521
2522 // Read the GC count while holding the Heap_lock
2523 gc_count_before = total_collections();
2524 old_marking_count_before = _old_marking_cycles_started;
2525 }
2526
2527 if (should_do_concurrent_full_gc(cause)) {
2528 // Schedule an initial-mark evacuation pause that will start a
2529 // concurrent cycle. We're setting word_size to 0 which means that
2530 // we are not requesting a post-GC allocation.
2531 VM_G1IncCollectionPause op(gc_count_before,
2532 0, /* word_size */
2533 true, /* should_initiate_conc_mark */
2534 g1_policy()->max_pause_time_ms(),
2535 cause);
2536
2537 VMThread::execute(&op);
2538 if (!op.pause_succeeded()) {
2539 if (old_marking_count_before == _old_marking_cycles_started) {
2540 retry_gc = op.should_retry_gc();
2541 } else {
2542 // A Full GC happened while we were trying to schedule the
2543 // initial-mark GC. No point in starting a new cycle given
2544 // that the whole heap was collected anyway.
2545 }
2546
2547 if (retry_gc) {
2548 if (GC_locker::is_active_and_needs_gc()) {
2549 GC_locker::stall_until_clear();
2550 }
2551 }
2552 }
2553 } else {
2554 if (cause == GCCause::_gc_locker
2555 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2556
2557 // Schedule a standard evacuation pause. We're setting word_size
2558 // to 0 which means that we are not requesting a post-GC allocation.
2559 VM_G1IncCollectionPause op(gc_count_before,
2560 0, /* word_size */
2561 false, /* should_initiate_conc_mark */
2562 g1_policy()->max_pause_time_ms(),
2563 cause);
2564 VMThread::execute(&op);
2565 } else {
2566 // Schedule a Full GC.
2567 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2568 VMThread::execute(&op);
2569 }
2570 }
2571 } while (retry_gc);
2572 }
2573
2574 bool G1CollectedHeap::is_in(const void* p) const {
2575 if (_g1_committed.contains(p)) {
2576 // Given that we know that p is in the committed space,
2577 // heap_region_containing_raw() should successfully
2578 // return the containing region.
2579 HeapRegion* hr = heap_region_containing_raw(p);
2580 return hr->is_in(p);
2581 } else {
2582 return false;
2583 }
2584 }
2585
2586 // Iteration functions.
2587
2588 // Iterates an OopClosure over all ref-containing fields of objects
2589 // within a HeapRegion.
2590
2591 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2592 MemRegion _mr;
2593 ExtendedOopClosure* _cl;
2594 public:
2595 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2596 : _mr(mr), _cl(cl) {}
2597 bool doHeapRegion(HeapRegion* r) {
2598 if (!r->continuesHumongous()) {
2599 r->oop_iterate(_cl);
2600 }
2601 return false;
2602 }
2603 };
2604
2605 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2606 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2607 heap_region_iterate(&blk);
2608 }
2609
2610 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2611 IterateOopClosureRegionClosure blk(mr, cl);
2612 heap_region_iterate(&blk);
2613 }
2614
2615 // Iterates an ObjectClosure over all objects within a HeapRegion.
2616
2617 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2618 ObjectClosure* _cl;
2619 public:
2620 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2621 bool doHeapRegion(HeapRegion* r) {
2622 if (! r->continuesHumongous()) {
2623 r->object_iterate(_cl);
2624 }
2625 return false;
2626 }
2627 };
2628
2629 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2630 IterateObjectClosureRegionClosure blk(cl);
2631 heap_region_iterate(&blk);
2632 }
2633
2634 // Calls a SpaceClosure on a HeapRegion.
2635
2636 class SpaceClosureRegionClosure: public HeapRegionClosure {
2637 SpaceClosure* _cl;
2638 public:
2639 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2640 bool doHeapRegion(HeapRegion* r) {
2641 _cl->do_space(r);
2642 return false;
2643 }
2644 };
2645
2646 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2647 SpaceClosureRegionClosure blk(cl);
2648 heap_region_iterate(&blk);
2649 }
2650
2651 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2652 _hrs.iterate(cl);
2653 }
2654
2655 void
2656 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2657 uint worker_id,
2658 uint no_of_par_workers,
2659 jint claim_value) {
2660 const uint regions = n_regions();
2661 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2662 no_of_par_workers :
2663 1);
2664 assert(UseDynamicNumberOfGCThreads ||
2665 no_of_par_workers == workers()->total_workers(),
2666 "Non dynamic should use fixed number of workers");
2667 // try to spread out the starting points of the workers
2668 const HeapRegion* start_hr =
2669 start_region_for_worker(worker_id, no_of_par_workers);
2670 const uint start_index = start_hr->hrs_index();
2671
2672 // each worker will actually look at all regions
2673 for (uint count = 0; count < regions; ++count) {
2674 const uint index = (start_index + count) % regions;
2675 assert(0 <= index && index < regions, "sanity");
2676 HeapRegion* r = region_at(index);
2677 // we'll ignore "continues humongous" regions (we'll process them
2678 // when we come across their corresponding "start humongous"
2679 // region) and regions already claimed
2680 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2681 continue;
2682 }
2683 // OK, try to claim it
2684 if (r->claimHeapRegion(claim_value)) {
2685 // success!
2686 assert(!r->continuesHumongous(), "sanity");
2687 if (r->startsHumongous()) {
2688 // If the region is "starts humongous" we'll iterate over its
2689 // "continues humongous" first; in fact we'll do them
2690 // first. The order is important. In on case, calling the
2691 // closure on the "starts humongous" region might de-allocate
2692 // and clear all its "continues humongous" regions and, as a
2693 // result, we might end up processing them twice. So, we'll do
2694 // them first (notice: most closures will ignore them anyway) and
2695 // then we'll do the "starts humongous" region.
2696 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2697 HeapRegion* chr = region_at(ch_index);
2698
2699 // if the region has already been claimed or it's not
2700 // "continues humongous" we're done
2701 if (chr->claim_value() == claim_value ||
2702 !chr->continuesHumongous()) {
2703 break;
2704 }
2705
2706 // No one should have claimed it directly. We can given
2707 // that we claimed its "starts humongous" region.
2708 assert(chr->claim_value() != claim_value, "sanity");
2709 assert(chr->humongous_start_region() == r, "sanity");
2710
2711 if (chr->claimHeapRegion(claim_value)) {
2712 // we should always be able to claim it; no one else should
2713 // be trying to claim this region
2714
2715 bool res2 = cl->doHeapRegion(chr);
2716 assert(!res2, "Should not abort");
2717
2718 // Right now, this holds (i.e., no closure that actually
2719 // does something with "continues humongous" regions
2720 // clears them). We might have to weaken it in the future,
2721 // but let's leave these two asserts here for extra safety.
2722 assert(chr->continuesHumongous(), "should still be the case");
2723 assert(chr->humongous_start_region() == r, "sanity");
2724 } else {
2725 guarantee(false, "we should not reach here");
2726 }
2727 }
2728 }
2729
2730 assert(!r->continuesHumongous(), "sanity");
2731 bool res = cl->doHeapRegion(r);
2732 assert(!res, "Should not abort");
2733 }
2734 }
2735 }
2736
2737 class ResetClaimValuesClosure: public HeapRegionClosure {
2738 public:
2739 bool doHeapRegion(HeapRegion* r) {
2740 r->set_claim_value(HeapRegion::InitialClaimValue);
2741 return false;
2742 }
2743 };
2744
2745 void G1CollectedHeap::reset_heap_region_claim_values() {
2746 ResetClaimValuesClosure blk;
2747 heap_region_iterate(&blk);
2748 }
2749
2750 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2751 ResetClaimValuesClosure blk;
2752 collection_set_iterate(&blk);
2753 }
2754
2755 #ifdef ASSERT
2756 // This checks whether all regions in the heap have the correct claim
2757 // value. I also piggy-backed on this a check to ensure that the
2758 // humongous_start_region() information on "continues humongous"
2759 // regions is correct.
2760
2761 class CheckClaimValuesClosure : public HeapRegionClosure {
2762 private:
2763 jint _claim_value;
2764 uint _failures;
2765 HeapRegion* _sh_region;
2766
2767 public:
2768 CheckClaimValuesClosure(jint claim_value) :
2769 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2770 bool doHeapRegion(HeapRegion* r) {
2771 if (r->claim_value() != _claim_value) {
2772 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2773 "claim value = %d, should be %d",
2774 HR_FORMAT_PARAMS(r),
2775 r->claim_value(), _claim_value);
2776 ++_failures;
2777 }
2778 if (!r->isHumongous()) {
2779 _sh_region = NULL;
2780 } else if (r->startsHumongous()) {
2781 _sh_region = r;
2782 } else if (r->continuesHumongous()) {
2783 if (r->humongous_start_region() != _sh_region) {
2784 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2785 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2786 HR_FORMAT_PARAMS(r),
2787 r->humongous_start_region(),
2788 _sh_region);
2789 ++_failures;
2790 }
2791 }
2792 return false;
2793 }
2794 uint failures() { return _failures; }
2795 };
2796
2797 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2798 CheckClaimValuesClosure cl(claim_value);
2799 heap_region_iterate(&cl);
2800 return cl.failures() == 0;
2801 }
2802
2803 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2804 private:
2805 jint _claim_value;
2806 uint _failures;
2807
2808 public:
2809 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2810 _claim_value(claim_value), _failures(0) { }
2811
2812 uint failures() { return _failures; }
2813
2814 bool doHeapRegion(HeapRegion* hr) {
2815 assert(hr->in_collection_set(), "how?");
2816 assert(!hr->isHumongous(), "H-region in CSet");
2817 if (hr->claim_value() != _claim_value) {
2818 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2819 "claim value = %d, should be %d",
2820 HR_FORMAT_PARAMS(hr),
2821 hr->claim_value(), _claim_value);
2822 _failures += 1;
2823 }
2824 return false;
2825 }
2826 };
2827
2828 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2829 CheckClaimValuesInCSetHRClosure cl(claim_value);
2830 collection_set_iterate(&cl);
2831 return cl.failures() == 0;
2832 }
2833 #endif // ASSERT
2834
2835 // Clear the cached CSet starting regions and (more importantly)
2836 // the time stamps. Called when we reset the GC time stamp.
2837 void G1CollectedHeap::clear_cset_start_regions() {
2838 assert(_worker_cset_start_region != NULL, "sanity");
2839 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2840
2841 int n_queues = MAX2((int)ParallelGCThreads, 1);
2842 for (int i = 0; i < n_queues; i++) {
2843 _worker_cset_start_region[i] = NULL;
2844 _worker_cset_start_region_time_stamp[i] = 0;
2845 }
2846 }
2847
2848 // Given the id of a worker, obtain or calculate a suitable
2849 // starting region for iterating over the current collection set.
2850 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2851 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2852
2853 HeapRegion* result = NULL;
2854 unsigned gc_time_stamp = get_gc_time_stamp();
2855
2856 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2857 // Cached starting region for current worker was set
2858 // during the current pause - so it's valid.
2859 // Note: the cached starting heap region may be NULL
2860 // (when the collection set is empty).
2861 result = _worker_cset_start_region[worker_i];
2862 assert(result == NULL || result->in_collection_set(), "sanity");
2863 return result;
2864 }
2865
2866 // The cached entry was not valid so let's calculate
2867 // a suitable starting heap region for this worker.
2868
2869 // We want the parallel threads to start their collection
2870 // set iteration at different collection set regions to
2871 // avoid contention.
2872 // If we have:
2873 // n collection set regions
2874 // p threads
2875 // Then thread t will start at region floor ((t * n) / p)
2876
2877 result = g1_policy()->collection_set();
2878 if (G1CollectedHeap::use_parallel_gc_threads()) {
2879 uint cs_size = g1_policy()->cset_region_length();
2880 uint active_workers = workers()->active_workers();
2881 assert(UseDynamicNumberOfGCThreads ||
2882 active_workers == workers()->total_workers(),
2883 "Unless dynamic should use total workers");
2884
2885 uint end_ind = (cs_size * worker_i) / active_workers;
2886 uint start_ind = 0;
2887
2888 if (worker_i > 0 &&
2889 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2890 // Previous workers starting region is valid
2891 // so let's iterate from there
2892 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2893 result = _worker_cset_start_region[worker_i - 1];
2894 }
2895
2896 for (uint i = start_ind; i < end_ind; i++) {
2897 result = result->next_in_collection_set();
2898 }
2899 }
2900
2901 // Note: the calculated starting heap region may be NULL
2902 // (when the collection set is empty).
2903 assert(result == NULL || result->in_collection_set(), "sanity");
2904 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2905 "should be updated only once per pause");
2906 _worker_cset_start_region[worker_i] = result;
2907 OrderAccess::storestore();
2908 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2909 return result;
2910 }
2911
2912 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2913 uint no_of_par_workers) {
2914 uint worker_num =
2915 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2916 assert(UseDynamicNumberOfGCThreads ||
2917 no_of_par_workers == workers()->total_workers(),
2918 "Non dynamic should use fixed number of workers");
2919 const uint start_index = n_regions() * worker_i / worker_num;
2920 return region_at(start_index);
2921 }
2922
2923 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2924 HeapRegion* r = g1_policy()->collection_set();
2925 while (r != NULL) {
2926 HeapRegion* next = r->next_in_collection_set();
2927 if (cl->doHeapRegion(r)) {
2928 cl->incomplete();
2929 return;
2930 }
2931 r = next;
2932 }
2933 }
2934
2935 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2936 HeapRegionClosure *cl) {
2937 if (r == NULL) {
2938 // The CSet is empty so there's nothing to do.
2939 return;
2940 }
2941
2942 assert(r->in_collection_set(),
2943 "Start region must be a member of the collection set.");
2944 HeapRegion* cur = r;
2945 while (cur != NULL) {
2946 HeapRegion* next = cur->next_in_collection_set();
2947 if (cl->doHeapRegion(cur) && false) {
2948 cl->incomplete();
2949 return;
2950 }
2951 cur = next;
2952 }
2953 cur = g1_policy()->collection_set();
2954 while (cur != r) {
2955 HeapRegion* next = cur->next_in_collection_set();
2956 if (cl->doHeapRegion(cur) && false) {
2957 cl->incomplete();
2958 return;
2959 }
2960 cur = next;
2961 }
2962 }
2963
2964 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2965 return n_regions() > 0 ? region_at(0) : NULL;
2966 }
2967
2968
2969 Space* G1CollectedHeap::space_containing(const void* addr) const {
2970 return heap_region_containing(addr);
2971 }
2972
2973 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2974 Space* sp = space_containing(addr);
2975 return sp->block_start(addr);
2976 }
2977
2978 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2979 Space* sp = space_containing(addr);
2980 return sp->block_size(addr);
2981 }
2982
2983 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2984 Space* sp = space_containing(addr);
2985 return sp->block_is_obj(addr);
2986 }
2987
2988 bool G1CollectedHeap::supports_tlab_allocation() const {
2989 return true;
2990 }
2991
2992 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2993 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2994 }
2995
2996 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2997 return young_list()->eden_used_bytes();
2998 }
2999
3000 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3001 // must be smaller than the humongous object limit.
3002 size_t G1CollectedHeap::max_tlab_size() const {
3003 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3004 }
3005
3006 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3007 // Return the remaining space in the cur alloc region, but not less than
3008 // the min TLAB size.
3009
3010 // Also, this value can be at most the humongous object threshold,
3011 // since we can't allow tlabs to grow big enough to accommodate
3012 // humongous objects.
3013
3014 HeapRegion* hr = _mutator_alloc_region.get();
3015 size_t max_tlab = max_tlab_size() * wordSize;
3016 if (hr == NULL) {
3017 return max_tlab;
3018 } else {
3019 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3020 }
3021 }
3022
3023 size_t G1CollectedHeap::max_capacity() const {
3024 return _g1_reserved.byte_size();
3025 }
3026
3027 jlong G1CollectedHeap::millis_since_last_gc() {
3028 // assert(false, "NYI");
3029 return 0;
3030 }
3031
3032 void G1CollectedHeap::prepare_for_verify() {
3033 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3034 ensure_parsability(false);
3035 }
3036 g1_rem_set()->prepare_for_verify();
3037 }
3038
3039 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3040 VerifyOption vo) {
3041 switch (vo) {
3042 case VerifyOption_G1UsePrevMarking:
3043 return hr->obj_allocated_since_prev_marking(obj);
3044 case VerifyOption_G1UseNextMarking:
3045 return hr->obj_allocated_since_next_marking(obj);
3046 case VerifyOption_G1UseMarkWord:
3047 return false;
3048 default:
3049 ShouldNotReachHere();
3050 }
3051 return false; // keep some compilers happy
3052 }
3053
3054 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3055 switch (vo) {
3056 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3057 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3058 case VerifyOption_G1UseMarkWord: return NULL;
3059 default: ShouldNotReachHere();
3060 }
3061 return NULL; // keep some compilers happy
3062 }
3063
3064 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3065 switch (vo) {
3066 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3067 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3068 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3069 default: ShouldNotReachHere();
3070 }
3071 return false; // keep some compilers happy
3072 }
3073
3074 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3075 switch (vo) {
3076 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3077 case VerifyOption_G1UseNextMarking: return "NTAMS";
3078 case VerifyOption_G1UseMarkWord: return "NONE";
3079 default: ShouldNotReachHere();
3080 }
3081 return NULL; // keep some compilers happy
3082 }
3083
3084 class VerifyRootsClosure: public OopClosure {
3085 private:
3086 G1CollectedHeap* _g1h;
3087 VerifyOption _vo;
3088 bool _failures;
3089 public:
3090 // _vo == UsePrevMarking -> use "prev" marking information,
3091 // _vo == UseNextMarking -> use "next" marking information,
3092 // _vo == UseMarkWord -> use mark word from object header.
3093 VerifyRootsClosure(VerifyOption vo) :
3094 _g1h(G1CollectedHeap::heap()),
3095 _vo(vo),
3096 _failures(false) { }
3097
3098 bool failures() { return _failures; }
3099
3100 template <class T> void do_oop_nv(T* p) {
3101 T heap_oop = oopDesc::load_heap_oop(p);
3102 if (!oopDesc::is_null(heap_oop)) {
3103 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3104 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3105 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3106 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3107 if (_vo == VerifyOption_G1UseMarkWord) {
3108 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3109 }
3110 obj->print_on(gclog_or_tty);
3111 _failures = true;
3112 }
3113 }
3114 }
3115
3116 void do_oop(oop* p) { do_oop_nv(p); }
3117 void do_oop(narrowOop* p) { do_oop_nv(p); }
3118 };
3119
3120 class G1VerifyCodeRootOopClosure: public OopClosure {
3121 G1CollectedHeap* _g1h;
3122 OopClosure* _root_cl;
3123 nmethod* _nm;
3124 VerifyOption _vo;
3125 bool _failures;
3126
3127 template <class T> void do_oop_work(T* p) {
3128 // First verify that this root is live
3129 _root_cl->do_oop(p);
3130
3131 if (!G1VerifyHeapRegionCodeRoots) {
3132 // We're not verifying the code roots attached to heap region.
3133 return;
3134 }
3135
3136 // Don't check the code roots during marking verification in a full GC
3137 if (_vo == VerifyOption_G1UseMarkWord) {
3138 return;
3139 }
3140
3141 // Now verify that the current nmethod (which contains p) is
3142 // in the code root list of the heap region containing the
3143 // object referenced by p.
3144
3145 T heap_oop = oopDesc::load_heap_oop(p);
3146 if (!oopDesc::is_null(heap_oop)) {
3147 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3148
3149 // Now fetch the region containing the object
3150 HeapRegion* hr = _g1h->heap_region_containing(obj);
3151 HeapRegionRemSet* hrrs = hr->rem_set();
3152 // Verify that the strong code root list for this region
3153 // contains the nmethod
3154 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3155 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3156 "from nmethod "PTR_FORMAT" not in strong "
3157 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3158 p, _nm, hr->bottom(), hr->end());
3159 _failures = true;
3160 }
3161 }
3162 }
3163
3164 public:
3165 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3166 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3167
3168 void do_oop(oop* p) { do_oop_work(p); }
3169 void do_oop(narrowOop* p) { do_oop_work(p); }
3170
3171 void set_nmethod(nmethod* nm) { _nm = nm; }
3172 bool failures() { return _failures; }
3173 };
3174
3175 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3176 G1VerifyCodeRootOopClosure* _oop_cl;
3177
3178 public:
3179 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3180 _oop_cl(oop_cl) {}
3181
3182 void do_code_blob(CodeBlob* cb) {
3183 nmethod* nm = cb->as_nmethod_or_null();
3184 if (nm != NULL) {
3185 _oop_cl->set_nmethod(nm);
3186 nm->oops_do(_oop_cl);
3187 }
3188 }
3189 };
3190
3191 class YoungRefCounterClosure : public OopClosure {
3192 G1CollectedHeap* _g1h;
3193 int _count;
3194 public:
3195 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3196 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3197 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3198
3199 int count() { return _count; }
3200 void reset_count() { _count = 0; };
3201 };
3202
3203 class VerifyKlassClosure: public KlassClosure {
3204 YoungRefCounterClosure _young_ref_counter_closure;
3205 OopClosure *_oop_closure;
3206 public:
3207 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3208 void do_klass(Klass* k) {
3209 k->oops_do(_oop_closure);
3210
3211 _young_ref_counter_closure.reset_count();
3212 k->oops_do(&_young_ref_counter_closure);
3213 if (_young_ref_counter_closure.count() > 0) {
3214 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3215 }
3216 }
3217 };
3218
3219 class VerifyLivenessOopClosure: public OopClosure {
3220 G1CollectedHeap* _g1h;
3221 VerifyOption _vo;
3222 public:
3223 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3224 _g1h(g1h), _vo(vo)
3225 { }
3226 void do_oop(narrowOop *p) { do_oop_work(p); }
3227 void do_oop( oop *p) { do_oop_work(p); }
3228
3229 template <class T> void do_oop_work(T *p) {
3230 oop obj = oopDesc::load_decode_heap_oop(p);
3231 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3232 "Dead object referenced by a not dead object");
3233 }
3234 };
3235
3236 class VerifyObjsInRegionClosure: public ObjectClosure {
3237 private:
3238 G1CollectedHeap* _g1h;
3239 size_t _live_bytes;
3240 HeapRegion *_hr;
3241 VerifyOption _vo;
3242 public:
3243 // _vo == UsePrevMarking -> use "prev" marking information,
3244 // _vo == UseNextMarking -> use "next" marking information,
3245 // _vo == UseMarkWord -> use mark word from object header.
3246 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3247 : _live_bytes(0), _hr(hr), _vo(vo) {
3248 _g1h = G1CollectedHeap::heap();
3249 }
3250 void do_object(oop o) {
3251 VerifyLivenessOopClosure isLive(_g1h, _vo);
3252 assert(o != NULL, "Huh?");
3253 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3254 // If the object is alive according to the mark word,
3255 // then verify that the marking information agrees.
3256 // Note we can't verify the contra-positive of the
3257 // above: if the object is dead (according to the mark
3258 // word), it may not be marked, or may have been marked
3259 // but has since became dead, or may have been allocated
3260 // since the last marking.
3261 if (_vo == VerifyOption_G1UseMarkWord) {
3262 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3263 }
3264
3265 o->oop_iterate_no_header(&isLive);
3266 if (!_hr->obj_allocated_since_prev_marking(o)) {
3267 size_t obj_size = o->size(); // Make sure we don't overflow
3268 _live_bytes += (obj_size * HeapWordSize);
3269 }
3270 }
3271 }
3272 size_t live_bytes() { return _live_bytes; }
3273 };
3274
3275 class PrintObjsInRegionClosure : public ObjectClosure {
3276 HeapRegion *_hr;
3277 G1CollectedHeap *_g1;
3278 public:
3279 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3280 _g1 = G1CollectedHeap::heap();
3281 };
3282
3283 void do_object(oop o) {
3284 if (o != NULL) {
3285 HeapWord *start = (HeapWord *) o;
3286 size_t word_sz = o->size();
3287 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3288 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3289 (void*) o, word_sz,
3290 _g1->isMarkedPrev(o),
3291 _g1->isMarkedNext(o),
3292 _hr->obj_allocated_since_prev_marking(o));
3293 HeapWord *end = start + word_sz;
3294 HeapWord *cur;
3295 int *val;
3296 for (cur = start; cur < end; cur++) {
3297 val = (int *) cur;
3298 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3299 }
3300 }
3301 }
3302 };
3303
3304 class VerifyRegionClosure: public HeapRegionClosure {
3305 private:
3306 bool _par;
3307 VerifyOption _vo;
3308 bool _failures;
3309 public:
3310 // _vo == UsePrevMarking -> use "prev" marking information,
3311 // _vo == UseNextMarking -> use "next" marking information,
3312 // _vo == UseMarkWord -> use mark word from object header.
3313 VerifyRegionClosure(bool par, VerifyOption vo)
3314 : _par(par),
3315 _vo(vo),
3316 _failures(false) {}
3317
3318 bool failures() {
3319 return _failures;
3320 }
3321
3322 bool doHeapRegion(HeapRegion* r) {
3323 if (!r->continuesHumongous()) {
3324 bool failures = false;
3325 r->verify(_vo, &failures);
3326 if (failures) {
3327 _failures = true;
3328 } else {
3329 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3330 r->object_iterate(¬_dead_yet_cl);
3331 if (_vo != VerifyOption_G1UseNextMarking) {
3332 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3333 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3334 "max_live_bytes "SIZE_FORMAT" "
3335 "< calculated "SIZE_FORMAT,
3336 r->bottom(), r->end(),
3337 r->max_live_bytes(),
3338 not_dead_yet_cl.live_bytes());
3339 _failures = true;
3340 }
3341 } else {
3342 // When vo == UseNextMarking we cannot currently do a sanity
3343 // check on the live bytes as the calculation has not been
3344 // finalized yet.
3345 }
3346 }
3347 }
3348 return false; // stop the region iteration if we hit a failure
3349 }
3350 };
3351
3352 // This is the task used for parallel verification of the heap regions
3353
3354 class G1ParVerifyTask: public AbstractGangTask {
3355 private:
3356 G1CollectedHeap* _g1h;
3357 VerifyOption _vo;
3358 bool _failures;
3359
3360 public:
3361 // _vo == UsePrevMarking -> use "prev" marking information,
3362 // _vo == UseNextMarking -> use "next" marking information,
3363 // _vo == UseMarkWord -> use mark word from object header.
3364 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3365 AbstractGangTask("Parallel verify task"),
3366 _g1h(g1h),
3367 _vo(vo),
3368 _failures(false) { }
3369
3370 bool failures() {
3371 return _failures;
3372 }
3373
3374 void work(uint worker_id) {
3375 HandleMark hm;
3376 VerifyRegionClosure blk(true, _vo);
3377 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3378 _g1h->workers()->active_workers(),
3379 HeapRegion::ParVerifyClaimValue);
3380 if (blk.failures()) {
3381 _failures = true;
3382 }
3383 }
3384 };
3385
3386 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3387 if (SafepointSynchronize::is_at_safepoint()) {
3388 assert(Thread::current()->is_VM_thread(),
3389 "Expected to be executed serially by the VM thread at this point");
3390
3391 if (!silent) { gclog_or_tty->print("Roots "); }
3392 VerifyRootsClosure rootsCl(vo);
3393 VerifyKlassClosure klassCl(this, &rootsCl);
3394
3395 // We apply the relevant closures to all the oops in the
3396 // system dictionary, class loader data graph and the string table.
3397 // Don't verify the code cache here, since it's verified below.
3398 const int so = SO_AllClasses | SO_Strings;
3399
3400 // Need cleared claim bits for the strong roots processing
3401 ClassLoaderDataGraph::clear_claimed_marks();
3402
3403 process_strong_roots(true, // activate StrongRootsScope
3404 ScanningOption(so), // roots scanning options
3405 &rootsCl,
3406 &klassCl
3407 );
3408
3409 // Verify the nmethods in the code cache.
3410 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3411 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3412 CodeCache::blobs_do(&blobsCl);
3413
3414 bool failures = rootsCl.failures() || codeRootsCl.failures();
3415
3416 if (vo != VerifyOption_G1UseMarkWord) {
3417 // If we're verifying during a full GC then the region sets
3418 // will have been torn down at the start of the GC. Therefore
3419 // verifying the region sets will fail. So we only verify
3420 // the region sets when not in a full GC.
3421 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3422 verify_region_sets();
3423 }
3424
3425 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3426 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3427 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3428 "sanity check");
3429
3430 G1ParVerifyTask task(this, vo);
3431 assert(UseDynamicNumberOfGCThreads ||
3432 workers()->active_workers() == workers()->total_workers(),
3433 "If not dynamic should be using all the workers");
3434 int n_workers = workers()->active_workers();
3435 set_par_threads(n_workers);
3436 workers()->run_task(&task);
3437 set_par_threads(0);
3438 if (task.failures()) {
3439 failures = true;
3440 }
3441
3442 // Checks that the expected amount of parallel work was done.
3443 // The implication is that n_workers is > 0.
3444 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3445 "sanity check");
3446
3447 reset_heap_region_claim_values();
3448
3449 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3450 "sanity check");
3451 } else {
3452 VerifyRegionClosure blk(false, vo);
3453 heap_region_iterate(&blk);
3454 if (blk.failures()) {
3455 failures = true;
3456 }
3457 }
3458 if (!silent) gclog_or_tty->print("RemSet ");
3459 rem_set()->verify();
3460
3461 if (G1StringDedup::is_enabled()) {
3462 if (!silent) gclog_or_tty->print("StrDedup ");
3463 G1StringDedup::verify();
3464 }
3465
3466 if (failures) {
3467 gclog_or_tty->print_cr("Heap:");
3468 // It helps to have the per-region information in the output to
3469 // help us track down what went wrong. This is why we call
3470 // print_extended_on() instead of print_on().
3471 print_extended_on(gclog_or_tty);
3472 gclog_or_tty->print_cr("");
3473 #ifndef PRODUCT
3474 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3475 concurrent_mark()->print_reachable("at-verification-failure",
3476 vo, false /* all */);
3477 }
3478 #endif
3479 gclog_or_tty->flush();
3480 }
3481 guarantee(!failures, "there should not have been any failures");
3482 } else {
3483 if (!silent) {
3484 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3485 if (G1StringDedup::is_enabled()) {
3486 gclog_or_tty->print(", StrDedup");
3487 }
3488 gclog_or_tty->print(") ");
3489 }
3490 }
3491 }
3492
3493 void G1CollectedHeap::verify(bool silent) {
3494 verify(silent, VerifyOption_G1UsePrevMarking);
3495 }
3496
3497 double G1CollectedHeap::verify(bool guard, const char* msg) {
3498 double verify_time_ms = 0.0;
3499
3500 if (guard && total_collections() >= VerifyGCStartAt) {
3501 double verify_start = os::elapsedTime();
3502 HandleMark hm; // Discard invalid handles created during verification
3503 prepare_for_verify();
3504 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3505 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3506 }
3507
3508 return verify_time_ms;
3509 }
3510
3511 void G1CollectedHeap::verify_before_gc() {
3512 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3513 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3514 }
3515
3516 void G1CollectedHeap::verify_after_gc() {
3517 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3518 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3519 }
3520
3521 class PrintRegionClosure: public HeapRegionClosure {
3522 outputStream* _st;
3523 public:
3524 PrintRegionClosure(outputStream* st) : _st(st) {}
3525 bool doHeapRegion(HeapRegion* r) {
3526 r->print_on(_st);
3527 return false;
3528 }
3529 };
3530
3531 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3532 const HeapRegion* hr,
3533 const VerifyOption vo) const {
3534 switch (vo) {
3535 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3536 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3537 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3538 default: ShouldNotReachHere();
3539 }
3540 return false; // keep some compilers happy
3541 }
3542
3543 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3544 const VerifyOption vo) const {
3545 switch (vo) {
3546 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3547 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3548 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3549 default: ShouldNotReachHere();
3550 }
3551 return false; // keep some compilers happy
3552 }
3553
3554 void G1CollectedHeap::print_on(outputStream* st) const {
3555 st->print(" %-20s", "garbage-first heap");
3556 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3557 capacity()/K, used_unlocked()/K);
3558 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3559 _g1_storage.low_boundary(),
3560 _g1_storage.high(),
3561 _g1_storage.high_boundary());
3562 st->cr();
3563 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3564 uint young_regions = _young_list->length();
3565 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3566 (size_t) young_regions * HeapRegion::GrainBytes / K);
3567 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3568 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3569 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3570 st->cr();
3571 MetaspaceAux::print_on(st);
3572 }
3573
3574 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3575 print_on(st);
3576
3577 // Print the per-region information.
3578 st->cr();
3579 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3580 "HS=humongous(starts), HC=humongous(continues), "
3581 "CS=collection set, F=free, TS=gc time stamp, "
3582 "PTAMS=previous top-at-mark-start, "
3583 "NTAMS=next top-at-mark-start)");
3584 PrintRegionClosure blk(st);
3585 heap_region_iterate(&blk);
3586 }
3587
3588 void G1CollectedHeap::print_on_error(outputStream* st) const {
3589 this->CollectedHeap::print_on_error(st);
3590
3591 if (_cm != NULL) {
3592 st->cr();
3593 _cm->print_on_error(st);
3594 }
3595 }
3596
3597 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3598 if (G1CollectedHeap::use_parallel_gc_threads()) {
3599 workers()->print_worker_threads_on(st);
3600 }
3601 _cmThread->print_on(st);
3602 st->cr();
3603 _cm->print_worker_threads_on(st);
3604 _cg1r->print_worker_threads_on(st);
3605 if (G1StringDedup::is_enabled()) {
3606 G1StringDedup::print_worker_threads_on(st);
3607 }
3608 }
3609
3610 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3611 if (G1CollectedHeap::use_parallel_gc_threads()) {
3612 workers()->threads_do(tc);
3613 }
3614 tc->do_thread(_cmThread);
3615 _cg1r->threads_do(tc);
3616 if (G1StringDedup::is_enabled()) {
3617 G1StringDedup::threads_do(tc);
3618 }
3619 }
3620
3621 void G1CollectedHeap::print_tracing_info() const {
3622 // We'll overload this to mean "trace GC pause statistics."
3623 if (TraceYoungGenTime || TraceOldGenTime) {
3624 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3625 // to that.
3626 g1_policy()->print_tracing_info();
3627 }
3628 if (G1SummarizeRSetStats) {
3629 g1_rem_set()->print_summary_info();
3630 }
3631 if (G1SummarizeConcMark) {
3632 concurrent_mark()->print_summary_info();
3633 }
3634 g1_policy()->print_yg_surv_rate_info();
3635 SpecializationStats::print();
3636 }
3637
3638 #ifndef PRODUCT
3639 // Helpful for debugging RSet issues.
3640
3641 class PrintRSetsClosure : public HeapRegionClosure {
3642 private:
3643 const char* _msg;
3644 size_t _occupied_sum;
3645
3646 public:
3647 bool doHeapRegion(HeapRegion* r) {
3648 HeapRegionRemSet* hrrs = r->rem_set();
3649 size_t occupied = hrrs->occupied();
3650 _occupied_sum += occupied;
3651
3652 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3653 HR_FORMAT_PARAMS(r));
3654 if (occupied == 0) {
3655 gclog_or_tty->print_cr(" RSet is empty");
3656 } else {
3657 hrrs->print();
3658 }
3659 gclog_or_tty->print_cr("----------");
3660 return false;
3661 }
3662
3663 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3664 gclog_or_tty->cr();
3665 gclog_or_tty->print_cr("========================================");
3666 gclog_or_tty->print_cr(msg);
3667 gclog_or_tty->cr();
3668 }
3669
3670 ~PrintRSetsClosure() {
3671 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3672 gclog_or_tty->print_cr("========================================");
3673 gclog_or_tty->cr();
3674 }
3675 };
3676
3677 void G1CollectedHeap::print_cset_rsets() {
3678 PrintRSetsClosure cl("Printing CSet RSets");
3679 collection_set_iterate(&cl);
3680 }
3681
3682 void G1CollectedHeap::print_all_rsets() {
3683 PrintRSetsClosure cl("Printing All RSets");;
3684 heap_region_iterate(&cl);
3685 }
3686 #endif // PRODUCT
3687
3688 G1CollectedHeap* G1CollectedHeap::heap() {
3689 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3690 "not a garbage-first heap");
3691 return _g1h;
3692 }
3693
3694 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3695 // always_do_update_barrier = false;
3696 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3697 // Fill TLAB's and such
3698 accumulate_statistics_all_tlabs();
3699 ensure_parsability(true);
3700
3701 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3702 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3703 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3704 }
3705 }
3706
3707 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3708
3709 if (G1SummarizeRSetStats &&
3710 (G1SummarizeRSetStatsPeriod > 0) &&
3711 // we are at the end of the GC. Total collections has already been increased.
3712 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3713 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3714 }
3715
3716 // FIXME: what is this about?
3717 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3718 // is set.
3719 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3720 "derived pointer present"));
3721 // always_do_update_barrier = true;
3722
3723 resize_all_tlabs();
3724
3725 // We have just completed a GC. Update the soft reference
3726 // policy with the new heap occupancy
3727 Universe::update_heap_info_at_gc();
3728 }
3729
3730 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3731 unsigned int gc_count_before,
3732 bool* succeeded,
3733 GCCause::Cause gc_cause) {
3734 assert_heap_not_locked_and_not_at_safepoint();
3735 g1_policy()->record_stop_world_start();
3736 VM_G1IncCollectionPause op(gc_count_before,
3737 word_size,
3738 false, /* should_initiate_conc_mark */
3739 g1_policy()->max_pause_time_ms(),
3740 gc_cause);
3741 VMThread::execute(&op);
3742
3743 HeapWord* result = op.result();
3744 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3745 assert(result == NULL || ret_succeeded,
3746 "the result should be NULL if the VM did not succeed");
3747 *succeeded = ret_succeeded;
3748
3749 assert_heap_not_locked();
3750 return result;
3751 }
3752
3753 void
3754 G1CollectedHeap::doConcurrentMark() {
3755 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3756 if (!_cmThread->in_progress()) {
3757 _cmThread->set_started();
3758 CGC_lock->notify();
3759 }
3760 }
3761
3762 size_t G1CollectedHeap::pending_card_num() {
3763 size_t extra_cards = 0;
3764 JavaThread *curr = Threads::first();
3765 while (curr != NULL) {
3766 DirtyCardQueue& dcq = curr->dirty_card_queue();
3767 extra_cards += dcq.size();
3768 curr = curr->next();
3769 }
3770 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3771 size_t buffer_size = dcqs.buffer_size();
3772 size_t buffer_num = dcqs.completed_buffers_num();
3773
3774 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3775 // in bytes - not the number of 'entries'. We need to convert
3776 // into a number of cards.
3777 return (buffer_size * buffer_num + extra_cards) / oopSize;
3778 }
3779
3780 size_t G1CollectedHeap::cards_scanned() {
3781 return g1_rem_set()->cardsScanned();
3782 }
3783
3784 void
3785 G1CollectedHeap::setup_surviving_young_words() {
3786 assert(_surviving_young_words == NULL, "pre-condition");
3787 uint array_length = g1_policy()->young_cset_region_length();
3788 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3789 if (_surviving_young_words == NULL) {
3790 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3791 "Not enough space for young surv words summary.");
3792 }
3793 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3794 #ifdef ASSERT
3795 for (uint i = 0; i < array_length; ++i) {
3796 assert( _surviving_young_words[i] == 0, "memset above" );
3797 }
3798 #endif // !ASSERT
3799 }
3800
3801 void
3802 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3803 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3804 uint array_length = g1_policy()->young_cset_region_length();
3805 for (uint i = 0; i < array_length; ++i) {
3806 _surviving_young_words[i] += surv_young_words[i];
3807 }
3808 }
3809
3810 void
3811 G1CollectedHeap::cleanup_surviving_young_words() {
3812 guarantee( _surviving_young_words != NULL, "pre-condition" );
3813 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3814 _surviving_young_words = NULL;
3815 }
3816
3817 #ifdef ASSERT
3818 class VerifyCSetClosure: public HeapRegionClosure {
3819 public:
3820 bool doHeapRegion(HeapRegion* hr) {
3821 // Here we check that the CSet region's RSet is ready for parallel
3822 // iteration. The fields that we'll verify are only manipulated
3823 // when the region is part of a CSet and is collected. Afterwards,
3824 // we reset these fields when we clear the region's RSet (when the
3825 // region is freed) so they are ready when the region is
3826 // re-allocated. The only exception to this is if there's an
3827 // evacuation failure and instead of freeing the region we leave
3828 // it in the heap. In that case, we reset these fields during
3829 // evacuation failure handling.
3830 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3831
3832 // Here's a good place to add any other checks we'd like to
3833 // perform on CSet regions.
3834 return false;
3835 }
3836 };
3837 #endif // ASSERT
3838
3839 #if TASKQUEUE_STATS
3840 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3841 st->print_raw_cr("GC Task Stats");
3842 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3843 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3844 }
3845
3846 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3847 print_taskqueue_stats_hdr(st);
3848
3849 TaskQueueStats totals;
3850 const int n = workers() != NULL ? workers()->total_workers() : 1;
3851 for (int i = 0; i < n; ++i) {
3852 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3853 totals += task_queue(i)->stats;
3854 }
3855 st->print_raw("tot "); totals.print(st); st->cr();
3856
3857 DEBUG_ONLY(totals.verify());
3858 }
3859
3860 void G1CollectedHeap::reset_taskqueue_stats() {
3861 const int n = workers() != NULL ? workers()->total_workers() : 1;
3862 for (int i = 0; i < n; ++i) {
3863 task_queue(i)->stats.reset();
3864 }
3865 }
3866 #endif // TASKQUEUE_STATS
3867
3868 void G1CollectedHeap::log_gc_header() {
3869 if (!G1Log::fine()) {
3870 return;
3871 }
3872
3873 gclog_or_tty->date_stamp(PrintGCDateStamps);
3874 gclog_or_tty->stamp(PrintGCTimeStamps);
3875
3876 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3877 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3878 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3879
3880 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3881 }
3882
3883 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3884 if (!G1Log::fine()) {
3885 return;
3886 }
3887
3888 if (G1Log::finer()) {
3889 if (evacuation_failed()) {
3890 gclog_or_tty->print(" (to-space exhausted)");
3891 }
3892 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3893 g1_policy()->phase_times()->note_gc_end();
3894 g1_policy()->phase_times()->print(pause_time_sec);
3895 g1_policy()->print_detailed_heap_transition();
3896 } else {
3897 if (evacuation_failed()) {
3898 gclog_or_tty->print("--");
3899 }
3900 g1_policy()->print_heap_transition();
3901 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3902 }
3903 gclog_or_tty->flush();
3904 }
3905
3906 bool
3907 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3908 assert_at_safepoint(true /* should_be_vm_thread */);
3909 guarantee(!is_gc_active(), "collection is not reentrant");
3910
3911 if (GC_locker::check_active_before_gc()) {
3912 return false;
3913 }
3914
3915 _gc_timer_stw->register_gc_start();
3916
3917 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3918
3919 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3920 ResourceMark rm;
3921
3922 print_heap_before_gc();
3923 trace_heap_before_gc(_gc_tracer_stw);
3924
3925 verify_region_sets_optional();
3926 verify_dirty_young_regions();
3927
3928 // This call will decide whether this pause is an initial-mark
3929 // pause. If it is, during_initial_mark_pause() will return true
3930 // for the duration of this pause.
3931 g1_policy()->decide_on_conc_mark_initiation();
3932
3933 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3934 assert(!g1_policy()->during_initial_mark_pause() ||
3935 g1_policy()->gcs_are_young(), "sanity");
3936
3937 // We also do not allow mixed GCs during marking.
3938 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3939
3940 // Record whether this pause is an initial mark. When the current
3941 // thread has completed its logging output and it's safe to signal
3942 // the CM thread, the flag's value in the policy has been reset.
3943 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3944
3945 // Inner scope for scope based logging, timers, and stats collection
3946 {
3947 EvacuationInfo evacuation_info;
3948
3949 if (g1_policy()->during_initial_mark_pause()) {
3950 // We are about to start a marking cycle, so we increment the
3951 // full collection counter.
3952 increment_old_marking_cycles_started();
3953 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3954 }
3955
3956 _gc_tracer_stw->report_yc_type(yc_type());
3957
3958 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3959
3960 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3961 workers()->active_workers() : 1);
3962 double pause_start_sec = os::elapsedTime();
3963 g1_policy()->phase_times()->note_gc_start(active_workers);
3964 log_gc_header();
3965
3966 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3967 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3968
3969 // If the secondary_free_list is not empty, append it to the
3970 // free_list. No need to wait for the cleanup operation to finish;
3971 // the region allocation code will check the secondary_free_list
3972 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3973 // set, skip this step so that the region allocation code has to
3974 // get entries from the secondary_free_list.
3975 if (!G1StressConcRegionFreeing) {
3976 append_secondary_free_list_if_not_empty_with_lock();
3977 }
3978
3979 assert(check_young_list_well_formed(), "young list should be well formed");
3980 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3981 "sanity check");
3982
3983 // Don't dynamically change the number of GC threads this early. A value of
3984 // 0 is used to indicate serial work. When parallel work is done,
3985 // it will be set.
3986
3987 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3988 IsGCActiveMark x;
3989
3990 gc_prologue(false);
3991 increment_total_collections(false /* full gc */);
3992 increment_gc_time_stamp();
3993
3994 verify_before_gc();
3995 check_bitmaps("GC Start");
3996
3997 COMPILER2_PRESENT(DerivedPointerTable::clear());
3998
3999 // Please see comment in g1CollectedHeap.hpp and
4000 // G1CollectedHeap::ref_processing_init() to see how
4001 // reference processing currently works in G1.
4002
4003 // Enable discovery in the STW reference processor
4004 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4005 true /*verify_no_refs*/);
4006
4007 {
4008 // We want to temporarily turn off discovery by the
4009 // CM ref processor, if necessary, and turn it back on
4010 // on again later if we do. Using a scoped
4011 // NoRefDiscovery object will do this.
4012 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4013
4014 // Forget the current alloc region (we might even choose it to be part
4015 // of the collection set!).
4016 release_mutator_alloc_region();
4017
4018 // We should call this after we retire the mutator alloc
4019 // region(s) so that all the ALLOC / RETIRE events are generated
4020 // before the start GC event.
4021 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4022
4023 // This timing is only used by the ergonomics to handle our pause target.
4024 // It is unclear why this should not include the full pause. We will
4025 // investigate this in CR 7178365.
4026 //
4027 // Preserving the old comment here if that helps the investigation:
4028 //
4029 // The elapsed time induced by the start time below deliberately elides
4030 // the possible verification above.
4031 double sample_start_time_sec = os::elapsedTime();
4032
4033 #if YOUNG_LIST_VERBOSE
4034 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4035 _young_list->print();
4036 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4037 #endif // YOUNG_LIST_VERBOSE
4038
4039 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4040
4041 double scan_wait_start = os::elapsedTime();
4042 // We have to wait until the CM threads finish scanning the
4043 // root regions as it's the only way to ensure that all the
4044 // objects on them have been correctly scanned before we start
4045 // moving them during the GC.
4046 bool waited = _cm->root_regions()->wait_until_scan_finished();
4047 double wait_time_ms = 0.0;
4048 if (waited) {
4049 double scan_wait_end = os::elapsedTime();
4050 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4051 }
4052 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4053
4054 #if YOUNG_LIST_VERBOSE
4055 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4056 _young_list->print();
4057 #endif // YOUNG_LIST_VERBOSE
4058
4059 if (g1_policy()->during_initial_mark_pause()) {
4060 concurrent_mark()->checkpointRootsInitialPre();
4061 }
4062
4063 #if YOUNG_LIST_VERBOSE
4064 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4065 _young_list->print();
4066 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4067 #endif // YOUNG_LIST_VERBOSE
4068
4069 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4070
4071 _cm->note_start_of_gc();
4072 // We should not verify the per-thread SATB buffers given that
4073 // we have not filtered them yet (we'll do so during the
4074 // GC). We also call this after finalize_cset() to
4075 // ensure that the CSet has been finalized.
4076 _cm->verify_no_cset_oops(true /* verify_stacks */,
4077 true /* verify_enqueued_buffers */,
4078 false /* verify_thread_buffers */,
4079 true /* verify_fingers */);
4080
4081 if (_hr_printer.is_active()) {
4082 HeapRegion* hr = g1_policy()->collection_set();
4083 while (hr != NULL) {
4084 G1HRPrinter::RegionType type;
4085 if (!hr->is_young()) {
4086 type = G1HRPrinter::Old;
4087 } else if (hr->is_survivor()) {
4088 type = G1HRPrinter::Survivor;
4089 } else {
4090 type = G1HRPrinter::Eden;
4091 }
4092 _hr_printer.cset(hr);
4093 hr = hr->next_in_collection_set();
4094 }
4095 }
4096
4097 #ifdef ASSERT
4098 VerifyCSetClosure cl;
4099 collection_set_iterate(&cl);
4100 #endif // ASSERT
4101
4102 setup_surviving_young_words();
4103
4104 // Initialize the GC alloc regions.
4105 init_gc_alloc_regions(evacuation_info);
4106
4107 // Actually do the work...
4108 evacuate_collection_set(evacuation_info);
4109
4110 // We do this to mainly verify the per-thread SATB buffers
4111 // (which have been filtered by now) since we didn't verify
4112 // them earlier. No point in re-checking the stacks / enqueued
4113 // buffers given that the CSet has not changed since last time
4114 // we checked.
4115 _cm->verify_no_cset_oops(false /* verify_stacks */,
4116 false /* verify_enqueued_buffers */,
4117 true /* verify_thread_buffers */,
4118 true /* verify_fingers */);
4119
4120 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4121 g1_policy()->clear_collection_set();
4122
4123 cleanup_surviving_young_words();
4124
4125 // Start a new incremental collection set for the next pause.
4126 g1_policy()->start_incremental_cset_building();
4127
4128 clear_cset_fast_test();
4129
4130 _young_list->reset_sampled_info();
4131
4132 // Don't check the whole heap at this point as the
4133 // GC alloc regions from this pause have been tagged
4134 // as survivors and moved on to the survivor list.
4135 // Survivor regions will fail the !is_young() check.
4136 assert(check_young_list_empty(false /* check_heap */),
4137 "young list should be empty");
4138
4139 #if YOUNG_LIST_VERBOSE
4140 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4141 _young_list->print();
4142 #endif // YOUNG_LIST_VERBOSE
4143
4144 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4145 _young_list->first_survivor_region(),
4146 _young_list->last_survivor_region());
4147
4148 _young_list->reset_auxilary_lists();
4149
4150 if (evacuation_failed()) {
4151 _summary_bytes_used = recalculate_used();
4152 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4153 for (uint i = 0; i < n_queues; i++) {
4154 if (_evacuation_failed_info_array[i].has_failed()) {
4155 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4156 }
4157 }
4158 } else {
4159 // The "used" of the the collection set have already been subtracted
4160 // when they were freed. Add in the bytes evacuated.
4161 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4162 }
4163
4164 if (g1_policy()->during_initial_mark_pause()) {
4165 // We have to do this before we notify the CM threads that
4166 // they can start working to make sure that all the
4167 // appropriate initialization is done on the CM object.
4168 concurrent_mark()->checkpointRootsInitialPost();
4169 set_marking_started();
4170 // Note that we don't actually trigger the CM thread at
4171 // this point. We do that later when we're sure that
4172 // the current thread has completed its logging output.
4173 }
4174
4175 allocate_dummy_regions();
4176
4177 #if YOUNG_LIST_VERBOSE
4178 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4179 _young_list->print();
4180 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4181 #endif // YOUNG_LIST_VERBOSE
4182
4183 init_mutator_alloc_region();
4184
4185 {
4186 size_t expand_bytes = g1_policy()->expansion_amount();
4187 if (expand_bytes > 0) {
4188 size_t bytes_before = capacity();
4189 // No need for an ergo verbose message here,
4190 // expansion_amount() does this when it returns a value > 0.
4191 if (!expand(expand_bytes)) {
4192 // We failed to expand the heap so let's verify that
4193 // committed/uncommitted amount match the backing store
4194 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4195 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4196 }
4197 }
4198 }
4199
4200 // We redo the verification but now wrt to the new CSet which
4201 // has just got initialized after the previous CSet was freed.
4202 _cm->verify_no_cset_oops(true /* verify_stacks */,
4203 true /* verify_enqueued_buffers */,
4204 true /* verify_thread_buffers */,
4205 true /* verify_fingers */);
4206 _cm->note_end_of_gc();
4207
4208 // This timing is only used by the ergonomics to handle our pause target.
4209 // It is unclear why this should not include the full pause. We will
4210 // investigate this in CR 7178365.
4211 double sample_end_time_sec = os::elapsedTime();
4212 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4213 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4214
4215 MemoryService::track_memory_usage();
4216
4217 // In prepare_for_verify() below we'll need to scan the deferred
4218 // update buffers to bring the RSets up-to-date if
4219 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4220 // the update buffers we'll probably need to scan cards on the
4221 // regions we just allocated to (i.e., the GC alloc
4222 // regions). However, during the last GC we called
4223 // set_saved_mark() on all the GC alloc regions, so card
4224 // scanning might skip the [saved_mark_word()...top()] area of
4225 // those regions (i.e., the area we allocated objects into
4226 // during the last GC). But it shouldn't. Given that
4227 // saved_mark_word() is conditional on whether the GC time stamp
4228 // on the region is current or not, by incrementing the GC time
4229 // stamp here we invalidate all the GC time stamps on all the
4230 // regions and saved_mark_word() will simply return top() for
4231 // all the regions. This is a nicer way of ensuring this rather
4232 // than iterating over the regions and fixing them. In fact, the
4233 // GC time stamp increment here also ensures that
4234 // saved_mark_word() will return top() between pauses, i.e.,
4235 // during concurrent refinement. So we don't need the
4236 // is_gc_active() check to decided which top to use when
4237 // scanning cards (see CR 7039627).
4238 increment_gc_time_stamp();
4239
4240 verify_after_gc();
4241 check_bitmaps("GC End");
4242
4243 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4244 ref_processor_stw()->verify_no_references_recorded();
4245
4246 // CM reference discovery will be re-enabled if necessary.
4247 }
4248
4249 // We should do this after we potentially expand the heap so
4250 // that all the COMMIT events are generated before the end GC
4251 // event, and after we retire the GC alloc regions so that all
4252 // RETIRE events are generated before the end GC event.
4253 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4254
4255 if (mark_in_progress()) {
4256 concurrent_mark()->update_g1_committed();
4257 }
4258
4259 #ifdef TRACESPINNING
4260 ParallelTaskTerminator::print_termination_counts();
4261 #endif
4262
4263 gc_epilogue(false);
4264 }
4265
4266 // Print the remainder of the GC log output.
4267 log_gc_footer(os::elapsedTime() - pause_start_sec);
4268
4269 // It is not yet to safe to tell the concurrent mark to
4270 // start as we have some optional output below. We don't want the
4271 // output from the concurrent mark thread interfering with this
4272 // logging output either.
4273
4274 _hrs.verify_optional();
4275 verify_region_sets_optional();
4276
4277 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4278 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4279
4280 print_heap_after_gc();
4281 trace_heap_after_gc(_gc_tracer_stw);
4282
4283 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4284 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4285 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4286 // before any GC notifications are raised.
4287 g1mm()->update_sizes();
4288
4289 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4290 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4291 _gc_timer_stw->register_gc_end();
4292 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4293 }
4294 // It should now be safe to tell the concurrent mark thread to start
4295 // without its logging output interfering with the logging output
4296 // that came from the pause.
4297
4298 if (should_start_conc_mark) {
4299 // CAUTION: after the doConcurrentMark() call below,
4300 // the concurrent marking thread(s) could be running
4301 // concurrently with us. Make sure that anything after
4302 // this point does not assume that we are the only GC thread
4303 // running. Note: of course, the actual marking work will
4304 // not start until the safepoint itself is released in
4305 // SuspendibleThreadSet::desynchronize().
4306 doConcurrentMark();
4307 }
4308
4309 return true;
4310 }
4311
4312 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4313 {
4314 size_t gclab_word_size;
4315 switch (purpose) {
4316 case GCAllocForSurvived:
4317 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4318 break;
4319 case GCAllocForTenured:
4320 gclab_word_size = _old_plab_stats.desired_plab_sz();
4321 break;
4322 default:
4323 assert(false, "unknown GCAllocPurpose");
4324 gclab_word_size = _old_plab_stats.desired_plab_sz();
4325 break;
4326 }
4327
4328 // Prevent humongous PLAB sizes for two reasons:
4329 // * PLABs are allocated using a similar paths as oops, but should
4330 // never be in a humongous region
4331 // * Allowing humongous PLABs needlessly churns the region free lists
4332 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4333 }
4334
4335 void G1CollectedHeap::init_mutator_alloc_region() {
4336 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4337 _mutator_alloc_region.init();
4338 }
4339
4340 void G1CollectedHeap::release_mutator_alloc_region() {
4341 _mutator_alloc_region.release();
4342 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4343 }
4344
4345 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4346 assert_at_safepoint(true /* should_be_vm_thread */);
4347
4348 _survivor_gc_alloc_region.init();
4349 _old_gc_alloc_region.init();
4350 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4351 _retained_old_gc_alloc_region = NULL;
4352
4353 // We will discard the current GC alloc region if:
4354 // a) it's in the collection set (it can happen!),
4355 // b) it's already full (no point in using it),
4356 // c) it's empty (this means that it was emptied during
4357 // a cleanup and it should be on the free list now), or
4358 // d) it's humongous (this means that it was emptied
4359 // during a cleanup and was added to the free list, but
4360 // has been subsequently used to allocate a humongous
4361 // object that may be less than the region size).
4362 if (retained_region != NULL &&
4363 !retained_region->in_collection_set() &&
4364 !(retained_region->top() == retained_region->end()) &&
4365 !retained_region->is_empty() &&
4366 !retained_region->isHumongous()) {
4367 retained_region->set_saved_mark();
4368 // The retained region was added to the old region set when it was
4369 // retired. We have to remove it now, since we don't allow regions
4370 // we allocate to in the region sets. We'll re-add it later, when
4371 // it's retired again.
4372 _old_set.remove(retained_region);
4373 bool during_im = g1_policy()->during_initial_mark_pause();
4374 retained_region->note_start_of_copying(during_im);
4375 _old_gc_alloc_region.set(retained_region);
4376 _hr_printer.reuse(retained_region);
4377 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4378 }
4379 }
4380
4381 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4382 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4383 _old_gc_alloc_region.count());
4384 _survivor_gc_alloc_region.release();
4385 // If we have an old GC alloc region to release, we'll save it in
4386 // _retained_old_gc_alloc_region. If we don't
4387 // _retained_old_gc_alloc_region will become NULL. This is what we
4388 // want either way so no reason to check explicitly for either
4389 // condition.
4390 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4391
4392 if (ResizePLAB) {
4393 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4394 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4395 }
4396 }
4397
4398 void G1CollectedHeap::abandon_gc_alloc_regions() {
4399 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4400 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4401 _retained_old_gc_alloc_region = NULL;
4402 }
4403
4404 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4405 _drain_in_progress = false;
4406 set_evac_failure_closure(cl);
4407 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4408 }
4409
4410 void G1CollectedHeap::finalize_for_evac_failure() {
4411 assert(_evac_failure_scan_stack != NULL &&
4412 _evac_failure_scan_stack->length() == 0,
4413 "Postcondition");
4414 assert(!_drain_in_progress, "Postcondition");
4415 delete _evac_failure_scan_stack;
4416 _evac_failure_scan_stack = NULL;
4417 }
4418
4419 void G1CollectedHeap::remove_self_forwarding_pointers() {
4420 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4421
4422 double remove_self_forwards_start = os::elapsedTime();
4423
4424 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4425
4426 if (G1CollectedHeap::use_parallel_gc_threads()) {
4427 set_par_threads();
4428 workers()->run_task(&rsfp_task);
4429 set_par_threads(0);
4430 } else {
4431 rsfp_task.work(0);
4432 }
4433
4434 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4435
4436 // Reset the claim values in the regions in the collection set.
4437 reset_cset_heap_region_claim_values();
4438
4439 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4440
4441 // Now restore saved marks, if any.
4442 assert(_objs_with_preserved_marks.size() ==
4443 _preserved_marks_of_objs.size(), "Both or none.");
4444 while (!_objs_with_preserved_marks.is_empty()) {
4445 oop obj = _objs_with_preserved_marks.pop();
4446 markOop m = _preserved_marks_of_objs.pop();
4447 obj->set_mark(m);
4448 }
4449 _objs_with_preserved_marks.clear(true);
4450 _preserved_marks_of_objs.clear(true);
4451
4452 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4453 }
4454
4455 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4456 _evac_failure_scan_stack->push(obj);
4457 }
4458
4459 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4460 assert(_evac_failure_scan_stack != NULL, "precondition");
4461
4462 while (_evac_failure_scan_stack->length() > 0) {
4463 oop obj = _evac_failure_scan_stack->pop();
4464 _evac_failure_closure->set_region(heap_region_containing(obj));
4465 obj->oop_iterate_backwards(_evac_failure_closure);
4466 }
4467 }
4468
4469 oop
4470 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4471 oop old) {
4472 assert(obj_in_cs(old),
4473 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4474 (HeapWord*) old));
4475 markOop m = old->mark();
4476 oop forward_ptr = old->forward_to_atomic(old);
4477 if (forward_ptr == NULL) {
4478 // Forward-to-self succeeded.
4479 assert(_par_scan_state != NULL, "par scan state");
4480 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4481 uint queue_num = _par_scan_state->queue_num();
4482
4483 _evacuation_failed = true;
4484 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4485 if (_evac_failure_closure != cl) {
4486 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4487 assert(!_drain_in_progress,
4488 "Should only be true while someone holds the lock.");
4489 // Set the global evac-failure closure to the current thread's.
4490 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4491 set_evac_failure_closure(cl);
4492 // Now do the common part.
4493 handle_evacuation_failure_common(old, m);
4494 // Reset to NULL.
4495 set_evac_failure_closure(NULL);
4496 } else {
4497 // The lock is already held, and this is recursive.
4498 assert(_drain_in_progress, "This should only be the recursive case.");
4499 handle_evacuation_failure_common(old, m);
4500 }
4501 return old;
4502 } else {
4503 // Forward-to-self failed. Either someone else managed to allocate
4504 // space for this object (old != forward_ptr) or they beat us in
4505 // self-forwarding it (old == forward_ptr).
4506 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4507 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4508 "should not be in the CSet",
4509 (HeapWord*) old, (HeapWord*) forward_ptr));
4510 return forward_ptr;
4511 }
4512 }
4513
4514 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4515 preserve_mark_if_necessary(old, m);
4516
4517 HeapRegion* r = heap_region_containing(old);
4518 if (!r->evacuation_failed()) {
4519 r->set_evacuation_failed(true);
4520 _hr_printer.evac_failure(r);
4521 }
4522
4523 push_on_evac_failure_scan_stack(old);
4524
4525 if (!_drain_in_progress) {
4526 // prevent recursion in copy_to_survivor_space()
4527 _drain_in_progress = true;
4528 drain_evac_failure_scan_stack();
4529 _drain_in_progress = false;
4530 }
4531 }
4532
4533 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4534 assert(evacuation_failed(), "Oversaving!");
4535 // We want to call the "for_promotion_failure" version only in the
4536 // case of a promotion failure.
4537 if (m->must_be_preserved_for_promotion_failure(obj)) {
4538 _objs_with_preserved_marks.push(obj);
4539 _preserved_marks_of_objs.push(m);
4540 }
4541 }
4542
4543 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4544 size_t word_size) {
4545 if (purpose == GCAllocForSurvived) {
4546 HeapWord* result = survivor_attempt_allocation(word_size);
4547 if (result != NULL) {
4548 return result;
4549 } else {
4550 // Let's try to allocate in the old gen in case we can fit the
4551 // object there.
4552 return old_attempt_allocation(word_size);
4553 }
4554 } else {
4555 assert(purpose == GCAllocForTenured, "sanity");
4556 HeapWord* result = old_attempt_allocation(word_size);
4557 if (result != NULL) {
4558 return result;
4559 } else {
4560 // Let's try to allocate in the survivors in case we can fit the
4561 // object there.
4562 return survivor_attempt_allocation(word_size);
4563 }
4564 }
4565
4566 ShouldNotReachHere();
4567 // Trying to keep some compilers happy.
4568 return NULL;
4569 }
4570
4571 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4572 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4573
4574 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4575 : _g1h(g1h),
4576 _refs(g1h->task_queue(queue_num)),
4577 _dcq(&g1h->dirty_card_queue_set()),
4578 _ct_bs(g1h->g1_barrier_set()),
4579 _g1_rem(g1h->g1_rem_set()),
4580 _hash_seed(17), _queue_num(queue_num),
4581 _term_attempts(0),
4582 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4583 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4584 _age_table(false), _scanner(g1h, this, rp),
4585 _strong_roots_time(0), _term_time(0),
4586 _alloc_buffer_waste(0), _undo_waste(0) {
4587 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4588 // we "sacrifice" entry 0 to keep track of surviving bytes for
4589 // non-young regions (where the age is -1)
4590 // We also add a few elements at the beginning and at the end in
4591 // an attempt to eliminate cache contention
4592 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4593 uint array_length = PADDING_ELEM_NUM +
4594 real_length +
4595 PADDING_ELEM_NUM;
4596 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4597 if (_surviving_young_words_base == NULL)
4598 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4599 "Not enough space for young surv histo.");
4600 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4601 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4602
4603 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4604 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4605
4606 _start = os::elapsedTime();
4607 }
4608
4609 void
4610 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4611 {
4612 st->print_raw_cr("GC Termination Stats");
4613 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4614 " ------waste (KiB)------");
4615 st->print_raw_cr("thr ms ms % ms % attempts"
4616 " total alloc undo");
4617 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4618 " ------- ------- -------");
4619 }
4620
4621 void
4622 G1ParScanThreadState::print_termination_stats(int i,
4623 outputStream* const st) const
4624 {
4625 const double elapsed_ms = elapsed_time() * 1000.0;
4626 const double s_roots_ms = strong_roots_time() * 1000.0;
4627 const double term_ms = term_time() * 1000.0;
4628 st->print_cr("%3d %9.2f %9.2f %6.2f "
4629 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4630 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4631 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4632 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4633 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4634 alloc_buffer_waste() * HeapWordSize / K,
4635 undo_waste() * HeapWordSize / K);
4636 }
4637
4638 #ifdef ASSERT
4639 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4640 assert(ref != NULL, "invariant");
4641 assert(UseCompressedOops, "sanity");
4642 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4643 oop p = oopDesc::load_decode_heap_oop(ref);
4644 assert(_g1h->is_in_g1_reserved(p),
4645 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4646 return true;
4647 }
4648
4649 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4650 assert(ref != NULL, "invariant");
4651 if (has_partial_array_mask(ref)) {
4652 // Must be in the collection set--it's already been copied.
4653 oop p = clear_partial_array_mask(ref);
4654 assert(_g1h->obj_in_cs(p),
4655 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4656 } else {
4657 oop p = oopDesc::load_decode_heap_oop(ref);
4658 assert(_g1h->is_in_g1_reserved(p),
4659 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4660 }
4661 return true;
4662 }
4663
4664 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4665 if (ref.is_narrow()) {
4666 return verify_ref((narrowOop*) ref);
4667 } else {
4668 return verify_ref((oop*) ref);
4669 }
4670 }
4671 #endif // ASSERT
4672
4673 void G1ParScanThreadState::trim_queue() {
4674 assert(_evac_failure_cl != NULL, "not set");
4675
4676 StarTask ref;
4677 do {
4678 // Drain the overflow stack first, so other threads can steal.
4679 while (refs()->pop_overflow(ref)) {
4680 deal_with_reference(ref);
4681 }
4682
4683 while (refs()->pop_local(ref)) {
4684 deal_with_reference(ref);
4685 }
4686 } while (!refs()->is_empty());
4687 }
4688
4689 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4690 G1ParScanThreadState* par_scan_state) :
4691 _g1(g1), _par_scan_state(par_scan_state),
4692 _worker_id(par_scan_state->queue_num()) { }
4693
4694 void G1ParCopyHelper::mark_object(oop obj) {
4695 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4696
4697 // We know that the object is not moving so it's safe to read its size.
4698 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4699 }
4700
4701 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4702 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4703 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4704 assert(from_obj != to_obj, "should not be self-forwarded");
4705
4706 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4707 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4708
4709 // The object might be in the process of being copied by another
4710 // worker so we cannot trust that its to-space image is
4711 // well-formed. So we have to read its size from its from-space
4712 // image which we know should not be changing.
4713 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4714 }
4715
4716 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4717 size_t word_sz = old->size();
4718 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4719 // +1 to make the -1 indexes valid...
4720 int young_index = from_region->young_index_in_cset()+1;
4721 assert( (from_region->is_young() && young_index > 0) ||
4722 (!from_region->is_young() && young_index == 0), "invariant" );
4723 G1CollectorPolicy* g1p = _g1h->g1_policy();
4724 markOop m = old->mark();
4725 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4726 : m->age();
4727 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4728 word_sz);
4729 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4730 #ifndef PRODUCT
4731 // Should this evacuation fail?
4732 if (_g1h->evacuation_should_fail()) {
4733 if (obj_ptr != NULL) {
4734 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4735 obj_ptr = NULL;
4736 }
4737 }
4738 #endif // !PRODUCT
4739
4740 if (obj_ptr == NULL) {
4741 // This will either forward-to-self, or detect that someone else has
4742 // installed a forwarding pointer.
4743 return _g1h->handle_evacuation_failure_par(this, old);
4744 }
4745
4746 oop obj = oop(obj_ptr);
4747
4748 // We're going to allocate linearly, so might as well prefetch ahead.
4749 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4750
4751 oop forward_ptr = old->forward_to_atomic(obj);
4752 if (forward_ptr == NULL) {
4753 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4754
4755 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4756 // we actually allocated from and update alloc_purpose accordingly
4757 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4758 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4759
4760 if (g1p->track_object_age(alloc_purpose)) {
4761 // We could simply do obj->incr_age(). However, this causes a
4762 // performance issue. obj->incr_age() will first check whether
4763 // the object has a displaced mark by checking its mark word;
4764 // getting the mark word from the new location of the object
4765 // stalls. So, given that we already have the mark word and we
4766 // are about to install it anyway, it's better to increase the
4767 // age on the mark word, when the object does not have a
4768 // displaced mark word. We're not expecting many objects to have
4769 // a displaced marked word, so that case is not optimized
4770 // further (it could be...) and we simply call obj->incr_age().
4771
4772 if (m->has_displaced_mark_helper()) {
4773 // in this case, we have to install the mark word first,
4774 // otherwise obj looks to be forwarded (the old mark word,
4775 // which contains the forward pointer, was copied)
4776 obj->set_mark(m);
4777 obj->incr_age();
4778 } else {
4779 m = m->incr_age();
4780 obj->set_mark(m);
4781 }
4782 age_table()->add(obj, word_sz);
4783 } else {
4784 obj->set_mark(m);
4785 }
4786
4787 if (G1StringDedup::is_enabled()) {
4788 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4789 to_region->is_young(),
4790 queue_num(),
4791 obj);
4792 }
4793
4794 size_t* surv_young_words = surviving_young_words();
4795 surv_young_words[young_index] += word_sz;
4796
4797 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4798 // We keep track of the next start index in the length field of
4799 // the to-space object. The actual length can be found in the
4800 // length field of the from-space object.
4801 arrayOop(obj)->set_length(0);
4802 oop* old_p = set_partial_array_mask(old);
4803 push_on_queue(old_p);
4804 } else {
4805 // No point in using the slower heap_region_containing() method,
4806 // given that we know obj is in the heap.
4807 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4808 obj->oop_iterate_backwards(&_scanner);
4809 }
4810 } else {
4811 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4812 obj = forward_ptr;
4813 }
4814 return obj;
4815 }
4816
4817 template <class T>
4818 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4819 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4820 _scanned_klass->record_modified_oops();
4821 }
4822 }
4823
4824 template <G1Barrier barrier, bool do_mark_object>
4825 template <class T>
4826 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4827 T heap_oop = oopDesc::load_heap_oop(p);
4828
4829 if (oopDesc::is_null(heap_oop)) {
4830 return;
4831 }
4832
4833 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4834
4835 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4836
4837 if (_g1->in_cset_fast_test(obj)) {
4838 oop forwardee;
4839 if (obj->is_forwarded()) {
4840 forwardee = obj->forwardee();
4841 } else {
4842 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4843 }
4844 assert(forwardee != NULL, "forwardee should not be NULL");
4845 oopDesc::encode_store_heap_oop(p, forwardee);
4846 if (do_mark_object && forwardee != obj) {
4847 // If the object is self-forwarded we don't need to explicitly
4848 // mark it, the evacuation failure protocol will do so.
4849 mark_forwarded_object(obj, forwardee);
4850 }
4851
4852 if (barrier == G1BarrierKlass) {
4853 do_klass_barrier(p, forwardee);
4854 }
4855 } else {
4856 // The object is not in collection set. If we're a root scanning
4857 // closure during an initial mark pause (i.e. do_mark_object will
4858 // be true) then attempt to mark the object.
4859 if (do_mark_object) {
4860 mark_object(obj);
4861 }
4862 }
4863
4864 if (barrier == G1BarrierEvac) {
4865 _par_scan_state->update_rs(_from, p, _worker_id);
4866 }
4867 }
4868
4869 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4870 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4871
4872 class G1ParEvacuateFollowersClosure : public VoidClosure {
4873 protected:
4874 G1CollectedHeap* _g1h;
4875 G1ParScanThreadState* _par_scan_state;
4876 RefToScanQueueSet* _queues;
4877 ParallelTaskTerminator* _terminator;
4878
4879 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4880 RefToScanQueueSet* queues() { return _queues; }
4881 ParallelTaskTerminator* terminator() { return _terminator; }
4882
4883 public:
4884 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4885 G1ParScanThreadState* par_scan_state,
4886 RefToScanQueueSet* queues,
4887 ParallelTaskTerminator* terminator)
4888 : _g1h(g1h), _par_scan_state(par_scan_state),
4889 _queues(queues), _terminator(terminator) {}
4890
4891 void do_void();
4892
4893 private:
4894 inline bool offer_termination();
4895 };
4896
4897 bool G1ParEvacuateFollowersClosure::offer_termination() {
4898 G1ParScanThreadState* const pss = par_scan_state();
4899 pss->start_term_time();
4900 const bool res = terminator()->offer_termination();
4901 pss->end_term_time();
4902 return res;
4903 }
4904
4905 void G1ParEvacuateFollowersClosure::do_void() {
4906 StarTask stolen_task;
4907 G1ParScanThreadState* const pss = par_scan_state();
4908 pss->trim_queue();
4909
4910 do {
4911 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4912 assert(pss->verify_task(stolen_task), "sanity");
4913 if (stolen_task.is_narrow()) {
4914 pss->deal_with_reference((narrowOop*) stolen_task);
4915 } else {
4916 pss->deal_with_reference((oop*) stolen_task);
4917 }
4918
4919 // We've just processed a reference and we might have made
4920 // available new entries on the queues. So we have to make sure
4921 // we drain the queues as necessary.
4922 pss->trim_queue();
4923 }
4924 } while (!offer_termination());
4925 }
4926
4927 class G1KlassScanClosure : public KlassClosure {
4928 G1ParCopyHelper* _closure;
4929 bool _process_only_dirty;
4930 int _count;
4931 public:
4932 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4933 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4934 void do_klass(Klass* klass) {
4935 // If the klass has not been dirtied we know that there's
4936 // no references into the young gen and we can skip it.
4937 if (!_process_only_dirty || klass->has_modified_oops()) {
4938 // Clean the klass since we're going to scavenge all the metadata.
4939 klass->clear_modified_oops();
4940
4941 // Tell the closure that this klass is the Klass to scavenge
4942 // and is the one to dirty if oops are left pointing into the young gen.
4943 _closure->set_scanned_klass(klass);
4944
4945 klass->oops_do(_closure);
4946
4947 _closure->set_scanned_klass(NULL);
4948 }
4949 _count++;
4950 }
4951 };
4952
4953 class G1ParTask : public AbstractGangTask {
4954 protected:
4955 G1CollectedHeap* _g1h;
4956 RefToScanQueueSet *_queues;
4957 ParallelTaskTerminator _terminator;
4958 uint _n_workers;
4959
4960 Mutex _stats_lock;
4961 Mutex* stats_lock() { return &_stats_lock; }
4962
4963 size_t getNCards() {
4964 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4965 / G1BlockOffsetSharedArray::N_bytes;
4966 }
4967
4968 public:
4969 G1ParTask(G1CollectedHeap* g1h,
4970 RefToScanQueueSet *task_queues)
4971 : AbstractGangTask("G1 collection"),
4972 _g1h(g1h),
4973 _queues(task_queues),
4974 _terminator(0, _queues),
4975 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4976 {}
4977
4978 RefToScanQueueSet* queues() { return _queues; }
4979
4980 RefToScanQueue *work_queue(int i) {
4981 return queues()->queue(i);
4982 }
4983
4984 ParallelTaskTerminator* terminator() { return &_terminator; }
4985
4986 virtual void set_for_termination(int active_workers) {
4987 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4988 // in the young space (_par_seq_tasks) in the G1 heap
4989 // for SequentialSubTasksDone.
4990 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4991 // both of which need setting by set_n_termination().
4992 _g1h->SharedHeap::set_n_termination(active_workers);
4993 _g1h->set_n_termination(active_workers);
4994 terminator()->reset_for_reuse(active_workers);
4995 _n_workers = active_workers;
4996 }
4997
4998 void work(uint worker_id) {
4999 if (worker_id >= _n_workers) return; // no work needed this round
5000
5001 double start_time_ms = os::elapsedTime() * 1000.0;
5002 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5003
5004 {
5005 ResourceMark rm;
5006 HandleMark hm;
5007
5008 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5009
5010 G1ParScanThreadState pss(_g1h, worker_id, rp);
5011 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5012
5013 pss.set_evac_failure_closure(&evac_failure_cl);
5014
5015 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5016 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5017
5018 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5019 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5020
5021 bool only_young = _g1h->g1_policy()->gcs_are_young();
5022 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5023 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5024
5025 OopClosure* scan_root_cl = &only_scan_root_cl;
5026 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5027
5028 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5029 // We also need to mark copied objects.
5030 scan_root_cl = &scan_mark_root_cl;
5031 scan_klasses_cl = &scan_mark_klasses_cl_s;
5032 }
5033
5034 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5035
5036 // Don't scan the scavengable methods in the code cache as part
5037 // of strong root scanning. The code roots that point into a
5038 // region in the collection set are scanned when we scan the
5039 // region's RSet.
5040 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5041
5042 pss.start_strong_roots();
5043 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5044 SharedHeap::ScanningOption(so),
5045 scan_root_cl,
5046 &push_heap_rs_cl,
5047 scan_klasses_cl,
5048 worker_id);
5049 pss.end_strong_roots();
5050
5051 {
5052 double start = os::elapsedTime();
5053 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5054 evac.do_void();
5055 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5056 double term_ms = pss.term_time()*1000.0;
5057 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5058 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5059 }
5060 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5061 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5062
5063 if (ParallelGCVerbose) {
5064 MutexLocker x(stats_lock());
5065 pss.print_termination_stats(worker_id);
5066 }
5067
5068 assert(pss.refs()->is_empty(), "should be empty");
5069
5070 // Close the inner scope so that the ResourceMark and HandleMark
5071 // destructors are executed here and are included as part of the
5072 // "GC Worker Time".
5073 }
5074
5075 double end_time_ms = os::elapsedTime() * 1000.0;
5076 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5077 }
5078 };
5079
5080 // *** Common G1 Evacuation Stuff
5081
5082 // This method is run in a GC worker.
5083
5084 void
5085 G1CollectedHeap::
5086 g1_process_strong_roots(bool is_scavenging,
5087 ScanningOption so,
5088 OopClosure* scan_non_heap_roots,
5089 OopsInHeapRegionClosure* scan_rs,
5090 G1KlassScanClosure* scan_klasses,
5091 uint worker_i) {
5092
5093 // First scan the strong roots
5094 double ext_roots_start = os::elapsedTime();
5095 double closure_app_time_sec = 0.0;
5096
5097 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5098
5099 process_strong_roots(false, // no scoping; this is parallel code
5100 so,
5101 &buf_scan_non_heap_roots,
5102 scan_klasses
5103 );
5104
5105 // Now the CM ref_processor roots.
5106 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5107 // We need to treat the discovered reference lists of the
5108 // concurrent mark ref processor as roots and keep entries
5109 // (which are added by the marking threads) on them live
5110 // until they can be processed at the end of marking.
5111 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5112 }
5113
5114 // Finish up any enqueued closure apps (attributed as object copy time).
5115 buf_scan_non_heap_roots.done();
5116
5117 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5118
5119 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5120
5121 double ext_root_time_ms =
5122 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5123
5124 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5125
5126 // During conc marking we have to filter the per-thread SATB buffers
5127 // to make sure we remove any oops into the CSet (which will show up
5128 // as implicitly live).
5129 double satb_filtering_ms = 0.0;
5130 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5131 if (mark_in_progress()) {
5132 double satb_filter_start = os::elapsedTime();
5133
5134 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5135
5136 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5137 }
5138 }
5139 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5140
5141 // If this is an initial mark pause, and we're not scanning
5142 // the entire code cache, we need to mark the oops in the
5143 // strong code root lists for the regions that are not in
5144 // the collection set.
5145 // Note all threads participate in this set of root tasks.
5146 double mark_strong_code_roots_ms = 0.0;
5147 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5148 double mark_strong_roots_start = os::elapsedTime();
5149 mark_strong_code_roots(worker_i);
5150 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5151 }
5152 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5153
5154 // Now scan the complement of the collection set.
5155 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5156 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5157
5158 _process_strong_tasks->all_tasks_completed();
5159 }
5160
5161 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5162 private:
5163 BoolObjectClosure* _is_alive;
5164 int _initial_string_table_size;
5165 int _initial_symbol_table_size;
5166
5167 bool _process_strings;
5168 int _strings_processed;
5169 int _strings_removed;
5170
5171 bool _process_symbols;
5172 int _symbols_processed;
5173 int _symbols_removed;
5174
5175 bool _do_in_parallel;
5176 public:
5177 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5178 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5179 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5180 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5181 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5182
5183 _initial_string_table_size = StringTable::the_table()->table_size();
5184 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5185 if (process_strings) {
5186 StringTable::clear_parallel_claimed_index();
5187 }
5188 if (process_symbols) {
5189 SymbolTable::clear_parallel_claimed_index();
5190 }
5191 }
5192
5193 ~G1StringSymbolTableUnlinkTask() {
5194 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5195 err_msg("claim value %d after unlink less than initial string table size %d",
5196 StringTable::parallel_claimed_index(), _initial_string_table_size));
5197 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5198 err_msg("claim value %d after unlink less than initial symbol table size %d",
5199 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5200 }
5201
5202 void work(uint worker_id) {
5203 if (_do_in_parallel) {
5204 int strings_processed = 0;
5205 int strings_removed = 0;
5206 int symbols_processed = 0;
5207 int symbols_removed = 0;
5208 if (_process_strings) {
5209 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5210 Atomic::add(strings_processed, &_strings_processed);
5211 Atomic::add(strings_removed, &_strings_removed);
5212 }
5213 if (_process_symbols) {
5214 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5215 Atomic::add(symbols_processed, &_symbols_processed);
5216 Atomic::add(symbols_removed, &_symbols_removed);
5217 }
5218 } else {
5219 if (_process_strings) {
5220 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5221 }
5222 if (_process_symbols) {
5223 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5224 }
5225 }
5226 }
5227
5228 size_t strings_processed() const { return (size_t)_strings_processed; }
5229 size_t strings_removed() const { return (size_t)_strings_removed; }
5230
5231 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5232 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5233 };
5234
5235 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5236 bool process_strings, bool process_symbols) {
5237 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5238 _g1h->workers()->active_workers() : 1);
5239
5240 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5241 if (G1CollectedHeap::use_parallel_gc_threads()) {
5242 set_par_threads(n_workers);
5243 workers()->run_task(&g1_unlink_task);
5244 set_par_threads(0);
5245 } else {
5246 g1_unlink_task.work(0);
5247 }
5248 if (G1TraceStringSymbolTableScrubbing) {
5249 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5250 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5251 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5252 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5253 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5254 }
5255
5256 if (G1StringDedup::is_enabled()) {
5257 G1StringDedup::unlink(is_alive);
5258 }
5259 }
5260
5261 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5262 private:
5263 DirtyCardQueueSet* _queue;
5264 public:
5265 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5266
5267 virtual void work(uint worker_id) {
5268 double start_time = os::elapsedTime();
5269
5270 RedirtyLoggedCardTableEntryClosure cl;
5271 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5272 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5273 } else {
5274 _queue->apply_closure_to_all_completed_buffers(&cl);
5275 }
5276
5277 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5278 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5279 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5280 }
5281 };
5282
5283 void G1CollectedHeap::redirty_logged_cards() {
5284 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5285 double redirty_logged_cards_start = os::elapsedTime();
5286
5287 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5288 _g1h->workers()->active_workers() : 1);
5289
5290 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5291 dirty_card_queue_set().reset_for_par_iteration();
5292 if (use_parallel_gc_threads()) {
5293 set_par_threads(n_workers);
5294 workers()->run_task(&redirty_task);
5295 set_par_threads(0);
5296 } else {
5297 redirty_task.work(0);
5298 }
5299
5300 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5301 dcq.merge_bufferlists(&dirty_card_queue_set());
5302 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5303
5304 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5305 }
5306
5307 // Weak Reference Processing support
5308
5309 // An always "is_alive" closure that is used to preserve referents.
5310 // If the object is non-null then it's alive. Used in the preservation
5311 // of referent objects that are pointed to by reference objects
5312 // discovered by the CM ref processor.
5313 class G1AlwaysAliveClosure: public BoolObjectClosure {
5314 G1CollectedHeap* _g1;
5315 public:
5316 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5317 bool do_object_b(oop p) {
5318 if (p != NULL) {
5319 return true;
5320 }
5321 return false;
5322 }
5323 };
5324
5325 bool G1STWIsAliveClosure::do_object_b(oop p) {
5326 // An object is reachable if it is outside the collection set,
5327 // or is inside and copied.
5328 return !_g1->obj_in_cs(p) || p->is_forwarded();
5329 }
5330
5331 // Non Copying Keep Alive closure
5332 class G1KeepAliveClosure: public OopClosure {
5333 G1CollectedHeap* _g1;
5334 public:
5335 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5336 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5337 void do_oop( oop* p) {
5338 oop obj = *p;
5339
5340 if (_g1->obj_in_cs(obj)) {
5341 assert( obj->is_forwarded(), "invariant" );
5342 *p = obj->forwardee();
5343 }
5344 }
5345 };
5346
5347 // Copying Keep Alive closure - can be called from both
5348 // serial and parallel code as long as different worker
5349 // threads utilize different G1ParScanThreadState instances
5350 // and different queues.
5351
5352 class G1CopyingKeepAliveClosure: public OopClosure {
5353 G1CollectedHeap* _g1h;
5354 OopClosure* _copy_non_heap_obj_cl;
5355 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5356 G1ParScanThreadState* _par_scan_state;
5357
5358 public:
5359 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5360 OopClosure* non_heap_obj_cl,
5361 OopsInHeapRegionClosure* metadata_obj_cl,
5362 G1ParScanThreadState* pss):
5363 _g1h(g1h),
5364 _copy_non_heap_obj_cl(non_heap_obj_cl),
5365 _copy_metadata_obj_cl(metadata_obj_cl),
5366 _par_scan_state(pss)
5367 {}
5368
5369 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5370 virtual void do_oop( oop* p) { do_oop_work(p); }
5371
5372 template <class T> void do_oop_work(T* p) {
5373 oop obj = oopDesc::load_decode_heap_oop(p);
5374
5375 if (_g1h->obj_in_cs(obj)) {
5376 // If the referent object has been forwarded (either copied
5377 // to a new location or to itself in the event of an
5378 // evacuation failure) then we need to update the reference
5379 // field and, if both reference and referent are in the G1
5380 // heap, update the RSet for the referent.
5381 //
5382 // If the referent has not been forwarded then we have to keep
5383 // it alive by policy. Therefore we have copy the referent.
5384 //
5385 // If the reference field is in the G1 heap then we can push
5386 // on the PSS queue. When the queue is drained (after each
5387 // phase of reference processing) the object and it's followers
5388 // will be copied, the reference field set to point to the
5389 // new location, and the RSet updated. Otherwise we need to
5390 // use the the non-heap or metadata closures directly to copy
5391 // the referent object and update the pointer, while avoiding
5392 // updating the RSet.
5393
5394 if (_g1h->is_in_g1_reserved(p)) {
5395 _par_scan_state->push_on_queue(p);
5396 } else {
5397 assert(!ClassLoaderDataGraph::contains((address)p),
5398 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5399 PTR_FORMAT, p));
5400 _copy_non_heap_obj_cl->do_oop(p);
5401 }
5402 }
5403 }
5404 };
5405
5406 // Serial drain queue closure. Called as the 'complete_gc'
5407 // closure for each discovered list in some of the
5408 // reference processing phases.
5409
5410 class G1STWDrainQueueClosure: public VoidClosure {
5411 protected:
5412 G1CollectedHeap* _g1h;
5413 G1ParScanThreadState* _par_scan_state;
5414
5415 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5416
5417 public:
5418 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5419 _g1h(g1h),
5420 _par_scan_state(pss)
5421 { }
5422
5423 void do_void() {
5424 G1ParScanThreadState* const pss = par_scan_state();
5425 pss->trim_queue();
5426 }
5427 };
5428
5429 // Parallel Reference Processing closures
5430
5431 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5432 // processing during G1 evacuation pauses.
5433
5434 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5435 private:
5436 G1CollectedHeap* _g1h;
5437 RefToScanQueueSet* _queues;
5438 FlexibleWorkGang* _workers;
5439 int _active_workers;
5440
5441 public:
5442 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5443 FlexibleWorkGang* workers,
5444 RefToScanQueueSet *task_queues,
5445 int n_workers) :
5446 _g1h(g1h),
5447 _queues(task_queues),
5448 _workers(workers),
5449 _active_workers(n_workers)
5450 {
5451 assert(n_workers > 0, "shouldn't call this otherwise");
5452 }
5453
5454 // Executes the given task using concurrent marking worker threads.
5455 virtual void execute(ProcessTask& task);
5456 virtual void execute(EnqueueTask& task);
5457 };
5458
5459 // Gang task for possibly parallel reference processing
5460
5461 class G1STWRefProcTaskProxy: public AbstractGangTask {
5462 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5463 ProcessTask& _proc_task;
5464 G1CollectedHeap* _g1h;
5465 RefToScanQueueSet *_task_queues;
5466 ParallelTaskTerminator* _terminator;
5467
5468 public:
5469 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5470 G1CollectedHeap* g1h,
5471 RefToScanQueueSet *task_queues,
5472 ParallelTaskTerminator* terminator) :
5473 AbstractGangTask("Process reference objects in parallel"),
5474 _proc_task(proc_task),
5475 _g1h(g1h),
5476 _task_queues(task_queues),
5477 _terminator(terminator)
5478 {}
5479
5480 virtual void work(uint worker_id) {
5481 // The reference processing task executed by a single worker.
5482 ResourceMark rm;
5483 HandleMark hm;
5484
5485 G1STWIsAliveClosure is_alive(_g1h);
5486
5487 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5488 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5489
5490 pss.set_evac_failure_closure(&evac_failure_cl);
5491
5492 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5493 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5494
5495 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5496 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5497
5498 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5499 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5500
5501 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5502 // We also need to mark copied objects.
5503 copy_non_heap_cl = ©_mark_non_heap_cl;
5504 copy_metadata_cl = ©_mark_metadata_cl;
5505 }
5506
5507 // Keep alive closure.
5508 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5509
5510 // Complete GC closure
5511 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5512
5513 // Call the reference processing task's work routine.
5514 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5515
5516 // Note we cannot assert that the refs array is empty here as not all
5517 // of the processing tasks (specifically phase2 - pp2_work) execute
5518 // the complete_gc closure (which ordinarily would drain the queue) so
5519 // the queue may not be empty.
5520 }
5521 };
5522
5523 // Driver routine for parallel reference processing.
5524 // Creates an instance of the ref processing gang
5525 // task and has the worker threads execute it.
5526 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5527 assert(_workers != NULL, "Need parallel worker threads.");
5528
5529 ParallelTaskTerminator terminator(_active_workers, _queues);
5530 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5531
5532 _g1h->set_par_threads(_active_workers);
5533 _workers->run_task(&proc_task_proxy);
5534 _g1h->set_par_threads(0);
5535 }
5536
5537 // Gang task for parallel reference enqueueing.
5538
5539 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5540 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5541 EnqueueTask& _enq_task;
5542
5543 public:
5544 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5545 AbstractGangTask("Enqueue reference objects in parallel"),
5546 _enq_task(enq_task)
5547 { }
5548
5549 virtual void work(uint worker_id) {
5550 _enq_task.work(worker_id);
5551 }
5552 };
5553
5554 // Driver routine for parallel reference enqueueing.
5555 // Creates an instance of the ref enqueueing gang
5556 // task and has the worker threads execute it.
5557
5558 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5559 assert(_workers != NULL, "Need parallel worker threads.");
5560
5561 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5562
5563 _g1h->set_par_threads(_active_workers);
5564 _workers->run_task(&enq_task_proxy);
5565 _g1h->set_par_threads(0);
5566 }
5567
5568 // End of weak reference support closures
5569
5570 // Abstract task used to preserve (i.e. copy) any referent objects
5571 // that are in the collection set and are pointed to by reference
5572 // objects discovered by the CM ref processor.
5573
5574 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5575 protected:
5576 G1CollectedHeap* _g1h;
5577 RefToScanQueueSet *_queues;
5578 ParallelTaskTerminator _terminator;
5579 uint _n_workers;
5580
5581 public:
5582 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5583 AbstractGangTask("ParPreserveCMReferents"),
5584 _g1h(g1h),
5585 _queues(task_queues),
5586 _terminator(workers, _queues),
5587 _n_workers(workers)
5588 { }
5589
5590 void work(uint worker_id) {
5591 ResourceMark rm;
5592 HandleMark hm;
5593
5594 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5595 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5596
5597 pss.set_evac_failure_closure(&evac_failure_cl);
5598
5599 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5600
5601
5602 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5603 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5604
5605 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5606 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5607
5608 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5609 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5610
5611 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5612 // We also need to mark copied objects.
5613 copy_non_heap_cl = ©_mark_non_heap_cl;
5614 copy_metadata_cl = ©_mark_metadata_cl;
5615 }
5616
5617 // Is alive closure
5618 G1AlwaysAliveClosure always_alive(_g1h);
5619
5620 // Copying keep alive closure. Applied to referent objects that need
5621 // to be copied.
5622 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5623
5624 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5625
5626 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5627 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5628
5629 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5630 // So this must be true - but assert just in case someone decides to
5631 // change the worker ids.
5632 assert(0 <= worker_id && worker_id < limit, "sanity");
5633 assert(!rp->discovery_is_atomic(), "check this code");
5634
5635 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5636 for (uint idx = worker_id; idx < limit; idx += stride) {
5637 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5638
5639 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5640 while (iter.has_next()) {
5641 // Since discovery is not atomic for the CM ref processor, we
5642 // can see some null referent objects.
5643 iter.load_ptrs(DEBUG_ONLY(true));
5644 oop ref = iter.obj();
5645
5646 // This will filter nulls.
5647 if (iter.is_referent_alive()) {
5648 iter.make_referent_alive();
5649 }
5650 iter.move_to_next();
5651 }
5652 }
5653
5654 // Drain the queue - which may cause stealing
5655 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5656 drain_queue.do_void();
5657 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5658 assert(pss.refs()->is_empty(), "should be");
5659 }
5660 };
5661
5662 // Weak Reference processing during an evacuation pause (part 1).
5663 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5664 double ref_proc_start = os::elapsedTime();
5665
5666 ReferenceProcessor* rp = _ref_processor_stw;
5667 assert(rp->discovery_enabled(), "should have been enabled");
5668
5669 // Any reference objects, in the collection set, that were 'discovered'
5670 // by the CM ref processor should have already been copied (either by
5671 // applying the external root copy closure to the discovered lists, or
5672 // by following an RSet entry).
5673 //
5674 // But some of the referents, that are in the collection set, that these
5675 // reference objects point to may not have been copied: the STW ref
5676 // processor would have seen that the reference object had already
5677 // been 'discovered' and would have skipped discovering the reference,
5678 // but would not have treated the reference object as a regular oop.
5679 // As a result the copy closure would not have been applied to the
5680 // referent object.
5681 //
5682 // We need to explicitly copy these referent objects - the references
5683 // will be processed at the end of remarking.
5684 //
5685 // We also need to do this copying before we process the reference
5686 // objects discovered by the STW ref processor in case one of these
5687 // referents points to another object which is also referenced by an
5688 // object discovered by the STW ref processor.
5689
5690 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5691 no_of_gc_workers == workers()->active_workers(),
5692 "Need to reset active GC workers");
5693
5694 set_par_threads(no_of_gc_workers);
5695 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5696 no_of_gc_workers,
5697 _task_queues);
5698
5699 if (G1CollectedHeap::use_parallel_gc_threads()) {
5700 workers()->run_task(&keep_cm_referents);
5701 } else {
5702 keep_cm_referents.work(0);
5703 }
5704
5705 set_par_threads(0);
5706
5707 // Closure to test whether a referent is alive.
5708 G1STWIsAliveClosure is_alive(this);
5709
5710 // Even when parallel reference processing is enabled, the processing
5711 // of JNI refs is serial and performed serially by the current thread
5712 // rather than by a worker. The following PSS will be used for processing
5713 // JNI refs.
5714
5715 // Use only a single queue for this PSS.
5716 G1ParScanThreadState pss(this, 0, NULL);
5717
5718 // We do not embed a reference processor in the copying/scanning
5719 // closures while we're actually processing the discovered
5720 // reference objects.
5721 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5722
5723 pss.set_evac_failure_closure(&evac_failure_cl);
5724
5725 assert(pss.refs()->is_empty(), "pre-condition");
5726
5727 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5728 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5729
5730 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5731 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5732
5733 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5734 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5735
5736 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5737 // We also need to mark copied objects.
5738 copy_non_heap_cl = ©_mark_non_heap_cl;
5739 copy_metadata_cl = ©_mark_metadata_cl;
5740 }
5741
5742 // Keep alive closure.
5743 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5744
5745 // Serial Complete GC closure
5746 G1STWDrainQueueClosure drain_queue(this, &pss);
5747
5748 // Setup the soft refs policy...
5749 rp->setup_policy(false);
5750
5751 ReferenceProcessorStats stats;
5752 if (!rp->processing_is_mt()) {
5753 // Serial reference processing...
5754 stats = rp->process_discovered_references(&is_alive,
5755 &keep_alive,
5756 &drain_queue,
5757 NULL,
5758 _gc_timer_stw);
5759 } else {
5760 // Parallel reference processing
5761 assert(rp->num_q() == no_of_gc_workers, "sanity");
5762 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5763
5764 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5765 stats = rp->process_discovered_references(&is_alive,
5766 &keep_alive,
5767 &drain_queue,
5768 &par_task_executor,
5769 _gc_timer_stw);
5770 }
5771
5772 _gc_tracer_stw->report_gc_reference_stats(stats);
5773
5774 // We have completed copying any necessary live referent objects.
5775 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5776
5777 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5778 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5779 }
5780
5781 // Weak Reference processing during an evacuation pause (part 2).
5782 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5783 double ref_enq_start = os::elapsedTime();
5784
5785 ReferenceProcessor* rp = _ref_processor_stw;
5786 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5787
5788 // Now enqueue any remaining on the discovered lists on to
5789 // the pending list.
5790 if (!rp->processing_is_mt()) {
5791 // Serial reference processing...
5792 rp->enqueue_discovered_references();
5793 } else {
5794 // Parallel reference enqueueing
5795
5796 assert(no_of_gc_workers == workers()->active_workers(),
5797 "Need to reset active workers");
5798 assert(rp->num_q() == no_of_gc_workers, "sanity");
5799 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5800
5801 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5802 rp->enqueue_discovered_references(&par_task_executor);
5803 }
5804
5805 rp->verify_no_references_recorded();
5806 assert(!rp->discovery_enabled(), "should have been disabled");
5807
5808 // FIXME
5809 // CM's reference processing also cleans up the string and symbol tables.
5810 // Should we do that here also? We could, but it is a serial operation
5811 // and could significantly increase the pause time.
5812
5813 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5814 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5815 }
5816
5817 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5818 _expand_heap_after_alloc_failure = true;
5819 _evacuation_failed = false;
5820
5821 // Should G1EvacuationFailureALot be in effect for this GC?
5822 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5823
5824 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5825
5826 // Disable the hot card cache.
5827 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5828 hot_card_cache->reset_hot_cache_claimed_index();
5829 hot_card_cache->set_use_cache(false);
5830
5831 uint n_workers;
5832 if (G1CollectedHeap::use_parallel_gc_threads()) {
5833 n_workers =
5834 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5835 workers()->active_workers(),
5836 Threads::number_of_non_daemon_threads());
5837 assert(UseDynamicNumberOfGCThreads ||
5838 n_workers == workers()->total_workers(),
5839 "If not dynamic should be using all the workers");
5840 workers()->set_active_workers(n_workers);
5841 set_par_threads(n_workers);
5842 } else {
5843 assert(n_par_threads() == 0,
5844 "Should be the original non-parallel value");
5845 n_workers = 1;
5846 }
5847
5848 G1ParTask g1_par_task(this, _task_queues);
5849
5850 init_for_evac_failure(NULL);
5851
5852 rem_set()->prepare_for_younger_refs_iterate(true);
5853
5854 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5855 double start_par_time_sec = os::elapsedTime();
5856 double end_par_time_sec;
5857
5858 {
5859 StrongRootsScope srs(this);
5860
5861 if (G1CollectedHeap::use_parallel_gc_threads()) {
5862 // The individual threads will set their evac-failure closures.
5863 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5864 // These tasks use ShareHeap::_process_strong_tasks
5865 assert(UseDynamicNumberOfGCThreads ||
5866 workers()->active_workers() == workers()->total_workers(),
5867 "If not dynamic should be using all the workers");
5868 workers()->run_task(&g1_par_task);
5869 } else {
5870 g1_par_task.set_for_termination(n_workers);
5871 g1_par_task.work(0);
5872 }
5873 end_par_time_sec = os::elapsedTime();
5874
5875 // Closing the inner scope will execute the destructor
5876 // for the StrongRootsScope object. We record the current
5877 // elapsed time before closing the scope so that time
5878 // taken for the SRS destructor is NOT included in the
5879 // reported parallel time.
5880 }
5881
5882 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5883 g1_policy()->phase_times()->record_par_time(par_time_ms);
5884
5885 double code_root_fixup_time_ms =
5886 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5887 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5888
5889 set_par_threads(0);
5890
5891 // Process any discovered reference objects - we have
5892 // to do this _before_ we retire the GC alloc regions
5893 // as we may have to copy some 'reachable' referent
5894 // objects (and their reachable sub-graphs) that were
5895 // not copied during the pause.
5896 process_discovered_references(n_workers);
5897
5898 // Weak root processing.
5899 {
5900 G1STWIsAliveClosure is_alive(this);
5901 G1KeepAliveClosure keep_alive(this);
5902 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5903 if (G1StringDedup::is_enabled()) {
5904 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5905 }
5906 }
5907
5908 release_gc_alloc_regions(n_workers, evacuation_info);
5909 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5910
5911 // Reset and re-enable the hot card cache.
5912 // Note the counts for the cards in the regions in the
5913 // collection set are reset when the collection set is freed.
5914 hot_card_cache->reset_hot_cache();
5915 hot_card_cache->set_use_cache(true);
5916
5917 // Migrate the strong code roots attached to each region in
5918 // the collection set. Ideally we would like to do this
5919 // after we have finished the scanning/evacuation of the
5920 // strong code roots for a particular heap region.
5921 migrate_strong_code_roots();
5922
5923 purge_code_root_memory();
5924
5925 if (g1_policy()->during_initial_mark_pause()) {
5926 // Reset the claim values set during marking the strong code roots
5927 reset_heap_region_claim_values();
5928 }
5929
5930 finalize_for_evac_failure();
5931
5932 if (evacuation_failed()) {
5933 remove_self_forwarding_pointers();
5934
5935 // Reset the G1EvacuationFailureALot counters and flags
5936 // Note: the values are reset only when an actual
5937 // evacuation failure occurs.
5938 NOT_PRODUCT(reset_evacuation_should_fail();)
5939 }
5940
5941 // Enqueue any remaining references remaining on the STW
5942 // reference processor's discovered lists. We need to do
5943 // this after the card table is cleaned (and verified) as
5944 // the act of enqueueing entries on to the pending list
5945 // will log these updates (and dirty their associated
5946 // cards). We need these updates logged to update any
5947 // RSets.
5948 enqueue_discovered_references(n_workers);
5949
5950 if (G1DeferredRSUpdate) {
5951 redirty_logged_cards();
5952 }
5953 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5954 }
5955
5956 void G1CollectedHeap::free_region(HeapRegion* hr,
5957 FreeRegionList* free_list,
5958 bool par,
5959 bool locked) {
5960 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5961 assert(!hr->is_empty(), "the region should not be empty");
5962 assert(free_list != NULL, "pre-condition");
5963
5964 if (G1VerifyBitmaps) {
5965 MemRegion mr(hr->bottom(), hr->end());
5966 concurrent_mark()->clearRangePrevBitmap(mr);
5967 }
5968
5969 // Clear the card counts for this region.
5970 // Note: we only need to do this if the region is not young
5971 // (since we don't refine cards in young regions).
5972 if (!hr->is_young()) {
5973 _cg1r->hot_card_cache()->reset_card_counts(hr);
5974 }
5975 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5976 free_list->add_ordered(hr);
5977 }
5978
5979 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5980 FreeRegionList* free_list,
5981 bool par) {
5982 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5983 assert(free_list != NULL, "pre-condition");
5984
5985 size_t hr_capacity = hr->capacity();
5986 // We need to read this before we make the region non-humongous,
5987 // otherwise the information will be gone.
5988 uint last_index = hr->last_hc_index();
5989 hr->set_notHumongous();
5990 free_region(hr, free_list, par);
5991
5992 uint i = hr->hrs_index() + 1;
5993 while (i < last_index) {
5994 HeapRegion* curr_hr = region_at(i);
5995 assert(curr_hr->continuesHumongous(), "invariant");
5996 curr_hr->set_notHumongous();
5997 free_region(curr_hr, free_list, par);
5998 i += 1;
5999 }
6000 }
6001
6002 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6003 const HeapRegionSetCount& humongous_regions_removed) {
6004 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6005 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6006 _old_set.bulk_remove(old_regions_removed);
6007 _humongous_set.bulk_remove(humongous_regions_removed);
6008 }
6009
6010 }
6011
6012 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6013 assert(list != NULL, "list can't be null");
6014 if (!list->is_empty()) {
6015 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6016 _free_list.add_ordered(list);
6017 }
6018 }
6019
6020 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6021 assert(_summary_bytes_used >= bytes,
6022 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6023 _summary_bytes_used, bytes));
6024 _summary_bytes_used -= bytes;
6025 }
6026
6027 class G1ParCleanupCTTask : public AbstractGangTask {
6028 G1SATBCardTableModRefBS* _ct_bs;
6029 G1CollectedHeap* _g1h;
6030 HeapRegion* volatile _su_head;
6031 public:
6032 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6033 G1CollectedHeap* g1h) :
6034 AbstractGangTask("G1 Par Cleanup CT Task"),
6035 _ct_bs(ct_bs), _g1h(g1h) { }
6036
6037 void work(uint worker_id) {
6038 HeapRegion* r;
6039 while (r = _g1h->pop_dirty_cards_region()) {
6040 clear_cards(r);
6041 }
6042 }
6043
6044 void clear_cards(HeapRegion* r) {
6045 // Cards of the survivors should have already been dirtied.
6046 if (!r->is_survivor()) {
6047 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6048 }
6049 }
6050 };
6051
6052 #ifndef PRODUCT
6053 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6054 G1CollectedHeap* _g1h;
6055 G1SATBCardTableModRefBS* _ct_bs;
6056 public:
6057 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6058 : _g1h(g1h), _ct_bs(ct_bs) { }
6059 virtual bool doHeapRegion(HeapRegion* r) {
6060 if (r->is_survivor()) {
6061 _g1h->verify_dirty_region(r);
6062 } else {
6063 _g1h->verify_not_dirty_region(r);
6064 }
6065 return false;
6066 }
6067 };
6068
6069 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6070 // All of the region should be clean.
6071 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6072 MemRegion mr(hr->bottom(), hr->end());
6073 ct_bs->verify_not_dirty_region(mr);
6074 }
6075
6076 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6077 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6078 // dirty allocated blocks as they allocate them. The thread that
6079 // retires each region and replaces it with a new one will do a
6080 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6081 // not dirty that area (one less thing to have to do while holding
6082 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6083 // is dirty.
6084 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6085 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6086 if (hr->is_young()) {
6087 ct_bs->verify_g1_young_region(mr);
6088 } else {
6089 ct_bs->verify_dirty_region(mr);
6090 }
6091 }
6092
6093 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6094 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6095 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6096 verify_dirty_region(hr);
6097 }
6098 }
6099
6100 void G1CollectedHeap::verify_dirty_young_regions() {
6101 verify_dirty_young_list(_young_list->first_region());
6102 }
6103
6104 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6105 HeapWord* tams, HeapWord* end) {
6106 guarantee(tams <= end,
6107 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6108 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6109 if (result < end) {
6110 gclog_or_tty->cr();
6111 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6112 bitmap_name, result);
6113 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6114 bitmap_name, tams, end);
6115 return false;
6116 }
6117 return true;
6118 }
6119
6120 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6121 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6122 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6123
6124 HeapWord* bottom = hr->bottom();
6125 HeapWord* ptams = hr->prev_top_at_mark_start();
6126 HeapWord* ntams = hr->next_top_at_mark_start();
6127 HeapWord* end = hr->end();
6128
6129 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6130
6131 bool res_n = true;
6132 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6133 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6134 // if we happen to be in that state.
6135 if (mark_in_progress() || !_cmThread->in_progress()) {
6136 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6137 }
6138 if (!res_p || !res_n) {
6139 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6140 HR_FORMAT_PARAMS(hr));
6141 gclog_or_tty->print_cr("#### Caller: %s", caller);
6142 return false;
6143 }
6144 return true;
6145 }
6146
6147 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6148 if (!G1VerifyBitmaps) return;
6149
6150 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6151 }
6152
6153 class G1VerifyBitmapClosure : public HeapRegionClosure {
6154 private:
6155 const char* _caller;
6156 G1CollectedHeap* _g1h;
6157 bool _failures;
6158
6159 public:
6160 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6161 _caller(caller), _g1h(g1h), _failures(false) { }
6162
6163 bool failures() { return _failures; }
6164
6165 virtual bool doHeapRegion(HeapRegion* hr) {
6166 if (hr->continuesHumongous()) return false;
6167
6168 bool result = _g1h->verify_bitmaps(_caller, hr);
6169 if (!result) {
6170 _failures = true;
6171 }
6172 return false;
6173 }
6174 };
6175
6176 void G1CollectedHeap::check_bitmaps(const char* caller) {
6177 if (!G1VerifyBitmaps) return;
6178
6179 G1VerifyBitmapClosure cl(caller, this);
6180 heap_region_iterate(&cl);
6181 guarantee(!cl.failures(), "bitmap verification");
6182 }
6183 #endif // PRODUCT
6184
6185 void G1CollectedHeap::cleanUpCardTable() {
6186 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6187 double start = os::elapsedTime();
6188
6189 {
6190 // Iterate over the dirty cards region list.
6191 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6192
6193 if (G1CollectedHeap::use_parallel_gc_threads()) {
6194 set_par_threads();
6195 workers()->run_task(&cleanup_task);
6196 set_par_threads(0);
6197 } else {
6198 while (_dirty_cards_region_list) {
6199 HeapRegion* r = _dirty_cards_region_list;
6200 cleanup_task.clear_cards(r);
6201 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6202 if (_dirty_cards_region_list == r) {
6203 // The last region.
6204 _dirty_cards_region_list = NULL;
6205 }
6206 r->set_next_dirty_cards_region(NULL);
6207 }
6208 }
6209 #ifndef PRODUCT
6210 if (G1VerifyCTCleanup || VerifyAfterGC) {
6211 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6212 heap_region_iterate(&cleanup_verifier);
6213 }
6214 #endif
6215 }
6216
6217 double elapsed = os::elapsedTime() - start;
6218 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6219 }
6220
6221 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6222 size_t pre_used = 0;
6223 FreeRegionList local_free_list("Local List for CSet Freeing");
6224
6225 double young_time_ms = 0.0;
6226 double non_young_time_ms = 0.0;
6227
6228 // Since the collection set is a superset of the the young list,
6229 // all we need to do to clear the young list is clear its
6230 // head and length, and unlink any young regions in the code below
6231 _young_list->clear();
6232
6233 G1CollectorPolicy* policy = g1_policy();
6234
6235 double start_sec = os::elapsedTime();
6236 bool non_young = true;
6237
6238 HeapRegion* cur = cs_head;
6239 int age_bound = -1;
6240 size_t rs_lengths = 0;
6241
6242 while (cur != NULL) {
6243 assert(!is_on_master_free_list(cur), "sanity");
6244 if (non_young) {
6245 if (cur->is_young()) {
6246 double end_sec = os::elapsedTime();
6247 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6248 non_young_time_ms += elapsed_ms;
6249
6250 start_sec = os::elapsedTime();
6251 non_young = false;
6252 }
6253 } else {
6254 if (!cur->is_young()) {
6255 double end_sec = os::elapsedTime();
6256 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6257 young_time_ms += elapsed_ms;
6258
6259 start_sec = os::elapsedTime();
6260 non_young = true;
6261 }
6262 }
6263
6264 rs_lengths += cur->rem_set()->occupied_locked();
6265
6266 HeapRegion* next = cur->next_in_collection_set();
6267 assert(cur->in_collection_set(), "bad CS");
6268 cur->set_next_in_collection_set(NULL);
6269 cur->set_in_collection_set(false);
6270
6271 if (cur->is_young()) {
6272 int index = cur->young_index_in_cset();
6273 assert(index != -1, "invariant");
6274 assert((uint) index < policy->young_cset_region_length(), "invariant");
6275 size_t words_survived = _surviving_young_words[index];
6276 cur->record_surv_words_in_group(words_survived);
6277
6278 // At this point the we have 'popped' cur from the collection set
6279 // (linked via next_in_collection_set()) but it is still in the
6280 // young list (linked via next_young_region()). Clear the
6281 // _next_young_region field.
6282 cur->set_next_young_region(NULL);
6283 } else {
6284 int index = cur->young_index_in_cset();
6285 assert(index == -1, "invariant");
6286 }
6287
6288 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6289 (!cur->is_young() && cur->young_index_in_cset() == -1),
6290 "invariant" );
6291
6292 if (!cur->evacuation_failed()) {
6293 MemRegion used_mr = cur->used_region();
6294
6295 // And the region is empty.
6296 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6297 pre_used += cur->used();
6298 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6299 } else {
6300 cur->uninstall_surv_rate_group();
6301 if (cur->is_young()) {
6302 cur->set_young_index_in_cset(-1);
6303 }
6304 cur->set_not_young();
6305 cur->set_evacuation_failed(false);
6306 // The region is now considered to be old.
6307 _old_set.add(cur);
6308 evacuation_info.increment_collectionset_used_after(cur->used());
6309 }
6310 cur = next;
6311 }
6312
6313 evacuation_info.set_regions_freed(local_free_list.length());
6314 policy->record_max_rs_lengths(rs_lengths);
6315 policy->cset_regions_freed();
6316
6317 double end_sec = os::elapsedTime();
6318 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6319
6320 if (non_young) {
6321 non_young_time_ms += elapsed_ms;
6322 } else {
6323 young_time_ms += elapsed_ms;
6324 }
6325
6326 prepend_to_freelist(&local_free_list);
6327 decrement_summary_bytes(pre_used);
6328 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6329 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6330 }
6331
6332 // This routine is similar to the above but does not record
6333 // any policy statistics or update free lists; we are abandoning
6334 // the current incremental collection set in preparation of a
6335 // full collection. After the full GC we will start to build up
6336 // the incremental collection set again.
6337 // This is only called when we're doing a full collection
6338 // and is immediately followed by the tearing down of the young list.
6339
6340 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6341 HeapRegion* cur = cs_head;
6342
6343 while (cur != NULL) {
6344 HeapRegion* next = cur->next_in_collection_set();
6345 assert(cur->in_collection_set(), "bad CS");
6346 cur->set_next_in_collection_set(NULL);
6347 cur->set_in_collection_set(false);
6348 cur->set_young_index_in_cset(-1);
6349 cur = next;
6350 }
6351 }
6352
6353 void G1CollectedHeap::set_free_regions_coming() {
6354 if (G1ConcRegionFreeingVerbose) {
6355 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6356 "setting free regions coming");
6357 }
6358
6359 assert(!free_regions_coming(), "pre-condition");
6360 _free_regions_coming = true;
6361 }
6362
6363 void G1CollectedHeap::reset_free_regions_coming() {
6364 assert(free_regions_coming(), "pre-condition");
6365
6366 {
6367 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6368 _free_regions_coming = false;
6369 SecondaryFreeList_lock->notify_all();
6370 }
6371
6372 if (G1ConcRegionFreeingVerbose) {
6373 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6374 "reset free regions coming");
6375 }
6376 }
6377
6378 void G1CollectedHeap::wait_while_free_regions_coming() {
6379 // Most of the time we won't have to wait, so let's do a quick test
6380 // first before we take the lock.
6381 if (!free_regions_coming()) {
6382 return;
6383 }
6384
6385 if (G1ConcRegionFreeingVerbose) {
6386 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6387 "waiting for free regions");
6388 }
6389
6390 {
6391 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6392 while (free_regions_coming()) {
6393 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6394 }
6395 }
6396
6397 if (G1ConcRegionFreeingVerbose) {
6398 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6399 "done waiting for free regions");
6400 }
6401 }
6402
6403 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6404 assert(heap_lock_held_for_gc(),
6405 "the heap lock should already be held by or for this thread");
6406 _young_list->push_region(hr);
6407 }
6408
6409 class NoYoungRegionsClosure: public HeapRegionClosure {
6410 private:
6411 bool _success;
6412 public:
6413 NoYoungRegionsClosure() : _success(true) { }
6414 bool doHeapRegion(HeapRegion* r) {
6415 if (r->is_young()) {
6416 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6417 r->bottom(), r->end());
6418 _success = false;
6419 }
6420 return false;
6421 }
6422 bool success() { return _success; }
6423 };
6424
6425 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6426 bool ret = _young_list->check_list_empty(check_sample);
6427
6428 if (check_heap) {
6429 NoYoungRegionsClosure closure;
6430 heap_region_iterate(&closure);
6431 ret = ret && closure.success();
6432 }
6433
6434 return ret;
6435 }
6436
6437 class TearDownRegionSetsClosure : public HeapRegionClosure {
6438 private:
6439 HeapRegionSet *_old_set;
6440
6441 public:
6442 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6443
6444 bool doHeapRegion(HeapRegion* r) {
6445 if (r->is_empty()) {
6446 // We ignore empty regions, we'll empty the free list afterwards
6447 } else if (r->is_young()) {
6448 // We ignore young regions, we'll empty the young list afterwards
6449 } else if (r->isHumongous()) {
6450 // We ignore humongous regions, we're not tearing down the
6451 // humongous region set
6452 } else {
6453 // The rest should be old
6454 _old_set->remove(r);
6455 }
6456 return false;
6457 }
6458
6459 ~TearDownRegionSetsClosure() {
6460 assert(_old_set->is_empty(), "post-condition");
6461 }
6462 };
6463
6464 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6465 assert_at_safepoint(true /* should_be_vm_thread */);
6466
6467 if (!free_list_only) {
6468 TearDownRegionSetsClosure cl(&_old_set);
6469 heap_region_iterate(&cl);
6470
6471 // Note that emptying the _young_list is postponed and instead done as
6472 // the first step when rebuilding the regions sets again. The reason for
6473 // this is that during a full GC string deduplication needs to know if
6474 // a collected region was young or old when the full GC was initiated.
6475 }
6476 _free_list.remove_all();
6477 }
6478
6479 class RebuildRegionSetsClosure : public HeapRegionClosure {
6480 private:
6481 bool _free_list_only;
6482 HeapRegionSet* _old_set;
6483 FreeRegionList* _free_list;
6484 size_t _total_used;
6485
6486 public:
6487 RebuildRegionSetsClosure(bool free_list_only,
6488 HeapRegionSet* old_set, FreeRegionList* free_list) :
6489 _free_list_only(free_list_only),
6490 _old_set(old_set), _free_list(free_list), _total_used(0) {
6491 assert(_free_list->is_empty(), "pre-condition");
6492 if (!free_list_only) {
6493 assert(_old_set->is_empty(), "pre-condition");
6494 }
6495 }
6496
6497 bool doHeapRegion(HeapRegion* r) {
6498 if (r->continuesHumongous()) {
6499 return false;
6500 }
6501
6502 if (r->is_empty()) {
6503 // Add free regions to the free list
6504 _free_list->add_as_tail(r);
6505 } else if (!_free_list_only) {
6506 assert(!r->is_young(), "we should not come across young regions");
6507
6508 if (r->isHumongous()) {
6509 // We ignore humongous regions, we left the humongous set unchanged
6510 } else {
6511 // The rest should be old, add them to the old set
6512 _old_set->add(r);
6513 }
6514 _total_used += r->used();
6515 }
6516
6517 return false;
6518 }
6519
6520 size_t total_used() {
6521 return _total_used;
6522 }
6523 };
6524
6525 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6526 assert_at_safepoint(true /* should_be_vm_thread */);
6527
6528 if (!free_list_only) {
6529 _young_list->empty_list();
6530 }
6531
6532 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6533 heap_region_iterate(&cl);
6534
6535 if (!free_list_only) {
6536 _summary_bytes_used = cl.total_used();
6537 }
6538 assert(_summary_bytes_used == recalculate_used(),
6539 err_msg("inconsistent _summary_bytes_used, "
6540 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6541 _summary_bytes_used, recalculate_used()));
6542 }
6543
6544 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6545 _refine_cte_cl->set_concurrent(concurrent);
6546 }
6547
6548 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6549 HeapRegion* hr = heap_region_containing(p);
6550 return hr->is_in(p);
6551 }
6552
6553 // Methods for the mutator alloc region
6554
6555 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6556 bool force) {
6557 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6558 assert(!force || g1_policy()->can_expand_young_list(),
6559 "if force is true we should be able to expand the young list");
6560 bool young_list_full = g1_policy()->is_young_list_full();
6561 if (force || !young_list_full) {
6562 HeapRegion* new_alloc_region = new_region(word_size,
6563 false /* is_old */,
6564 false /* do_expand */);
6565 if (new_alloc_region != NULL) {
6566 set_region_short_lived_locked(new_alloc_region);
6567 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6568 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6569 return new_alloc_region;
6570 }
6571 }
6572 return NULL;
6573 }
6574
6575 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6576 size_t allocated_bytes) {
6577 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6578 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6579
6580 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6581 _summary_bytes_used += allocated_bytes;
6582 _hr_printer.retire(alloc_region);
6583 // We update the eden sizes here, when the region is retired,
6584 // instead of when it's allocated, since this is the point that its
6585 // used space has been recored in _summary_bytes_used.
6586 g1mm()->update_eden_size();
6587 }
6588
6589 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6590 bool force) {
6591 return _g1h->new_mutator_alloc_region(word_size, force);
6592 }
6593
6594 void G1CollectedHeap::set_par_threads() {
6595 // Don't change the number of workers. Use the value previously set
6596 // in the workgroup.
6597 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6598 uint n_workers = workers()->active_workers();
6599 assert(UseDynamicNumberOfGCThreads ||
6600 n_workers == workers()->total_workers(),
6601 "Otherwise should be using the total number of workers");
6602 if (n_workers == 0) {
6603 assert(false, "Should have been set in prior evacuation pause.");
6604 n_workers = ParallelGCThreads;
6605 workers()->set_active_workers(n_workers);
6606 }
6607 set_par_threads(n_workers);
6608 }
6609
6610 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6611 size_t allocated_bytes) {
6612 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6613 }
6614
6615 // Methods for the GC alloc regions
6616
6617 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6618 uint count,
6619 GCAllocPurpose ap) {
6620 assert(FreeList_lock->owned_by_self(), "pre-condition");
6621
6622 if (count < g1_policy()->max_regions(ap)) {
6623 bool survivor = (ap == GCAllocForSurvived);
6624 HeapRegion* new_alloc_region = new_region(word_size,
6625 !survivor,
6626 true /* do_expand */);
6627 if (new_alloc_region != NULL) {
6628 // We really only need to do this for old regions given that we
6629 // should never scan survivors. But it doesn't hurt to do it
6630 // for survivors too.
6631 new_alloc_region->set_saved_mark();
6632 if (survivor) {
6633 new_alloc_region->set_survivor();
6634 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6635 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6636 } else {
6637 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6638 check_bitmaps("Old Region Allocation", new_alloc_region);
6639 }
6640 bool during_im = g1_policy()->during_initial_mark_pause();
6641 new_alloc_region->note_start_of_copying(during_im);
6642 return new_alloc_region;
6643 } else {
6644 g1_policy()->note_alloc_region_limit_reached(ap);
6645 }
6646 }
6647 return NULL;
6648 }
6649
6650 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6651 size_t allocated_bytes,
6652 GCAllocPurpose ap) {
6653 bool during_im = g1_policy()->during_initial_mark_pause();
6654 alloc_region->note_end_of_copying(during_im);
6655 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6656 if (ap == GCAllocForSurvived) {
6657 young_list()->add_survivor_region(alloc_region);
6658 } else {
6659 _old_set.add(alloc_region);
6660 }
6661 _hr_printer.retire(alloc_region);
6662 }
6663
6664 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6665 bool force) {
6666 assert(!force, "not supported for GC alloc regions");
6667 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6668 }
6669
6670 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6671 size_t allocated_bytes) {
6672 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6673 GCAllocForSurvived);
6674 }
6675
6676 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6677 bool force) {
6678 assert(!force, "not supported for GC alloc regions");
6679 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6680 }
6681
6682 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6683 size_t allocated_bytes) {
6684 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6685 GCAllocForTenured);
6686 }
6687 // Heap region set verification
6688
6689 class VerifyRegionListsClosure : public HeapRegionClosure {
6690 private:
6691 HeapRegionSet* _old_set;
6692 HeapRegionSet* _humongous_set;
6693 FreeRegionList* _free_list;
6694
6695 public:
6696 HeapRegionSetCount _old_count;
6697 HeapRegionSetCount _humongous_count;
6698 HeapRegionSetCount _free_count;
6699
6700 VerifyRegionListsClosure(HeapRegionSet* old_set,
6701 HeapRegionSet* humongous_set,
6702 FreeRegionList* free_list) :
6703 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6704 _old_count(), _humongous_count(), _free_count(){ }
6705
6706 bool doHeapRegion(HeapRegion* hr) {
6707 if (hr->continuesHumongous()) {
6708 return false;
6709 }
6710
6711 if (hr->is_young()) {
6712 // TODO
6713 } else if (hr->startsHumongous()) {
6714 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6715 _humongous_count.increment(1u, hr->capacity());
6716 } else if (hr->is_empty()) {
6717 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6718 _free_count.increment(1u, hr->capacity());
6719 } else {
6720 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6721 _old_count.increment(1u, hr->capacity());
6722 }
6723 return false;
6724 }
6725
6726 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6727 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6728 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6729 old_set->total_capacity_bytes(), _old_count.capacity()));
6730
6731 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6732 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6733 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6734
6735 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6736 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6737 free_list->total_capacity_bytes(), _free_count.capacity()));
6738 }
6739 };
6740
6741 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6742 HeapWord* bottom) {
6743 HeapWord* end = bottom + HeapRegion::GrainWords;
6744 MemRegion mr(bottom, end);
6745 assert(_g1_reserved.contains(mr), "invariant");
6746 // This might return NULL if the allocation fails
6747 return new HeapRegion(hrs_index, _bot_shared, mr);
6748 }
6749
6750 void G1CollectedHeap::verify_region_sets() {
6751 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6752
6753 // First, check the explicit lists.
6754 _free_list.verify_list();
6755 {
6756 // Given that a concurrent operation might be adding regions to
6757 // the secondary free list we have to take the lock before
6758 // verifying it.
6759 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6760 _secondary_free_list.verify_list();
6761 }
6762
6763 // If a concurrent region freeing operation is in progress it will
6764 // be difficult to correctly attributed any free regions we come
6765 // across to the correct free list given that they might belong to
6766 // one of several (free_list, secondary_free_list, any local lists,
6767 // etc.). So, if that's the case we will skip the rest of the
6768 // verification operation. Alternatively, waiting for the concurrent
6769 // operation to complete will have a non-trivial effect on the GC's
6770 // operation (no concurrent operation will last longer than the
6771 // interval between two calls to verification) and it might hide
6772 // any issues that we would like to catch during testing.
6773 if (free_regions_coming()) {
6774 return;
6775 }
6776
6777 // Make sure we append the secondary_free_list on the free_list so
6778 // that all free regions we will come across can be safely
6779 // attributed to the free_list.
6780 append_secondary_free_list_if_not_empty_with_lock();
6781
6782 // Finally, make sure that the region accounting in the lists is
6783 // consistent with what we see in the heap.
6784
6785 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6786 heap_region_iterate(&cl);
6787 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6788 }
6789
6790 // Optimized nmethod scanning
6791
6792 class RegisterNMethodOopClosure: public OopClosure {
6793 G1CollectedHeap* _g1h;
6794 nmethod* _nm;
6795
6796 template <class T> void do_oop_work(T* p) {
6797 T heap_oop = oopDesc::load_heap_oop(p);
6798 if (!oopDesc::is_null(heap_oop)) {
6799 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6800 HeapRegion* hr = _g1h->heap_region_containing(obj);
6801 assert(!hr->continuesHumongous(),
6802 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6803 " starting at "HR_FORMAT,
6804 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6805
6806 // HeapRegion::add_strong_code_root() avoids adding duplicate
6807 // entries but having duplicates is OK since we "mark" nmethods
6808 // as visited when we scan the strong code root lists during the GC.
6809 hr->add_strong_code_root(_nm);
6810 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6811 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6812 _nm, HR_FORMAT_PARAMS(hr)));
6813 }
6814 }
6815
6816 public:
6817 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6818 _g1h(g1h), _nm(nm) {}
6819
6820 void do_oop(oop* p) { do_oop_work(p); }
6821 void do_oop(narrowOop* p) { do_oop_work(p); }
6822 };
6823
6824 class UnregisterNMethodOopClosure: public OopClosure {
6825 G1CollectedHeap* _g1h;
6826 nmethod* _nm;
6827
6828 template <class T> void do_oop_work(T* p) {
6829 T heap_oop = oopDesc::load_heap_oop(p);
6830 if (!oopDesc::is_null(heap_oop)) {
6831 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6832 HeapRegion* hr = _g1h->heap_region_containing(obj);
6833 assert(!hr->continuesHumongous(),
6834 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6835 " starting at "HR_FORMAT,
6836 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6837
6838 hr->remove_strong_code_root(_nm);
6839 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6840 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6841 _nm, HR_FORMAT_PARAMS(hr)));
6842 }
6843 }
6844
6845 public:
6846 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6847 _g1h(g1h), _nm(nm) {}
6848
6849 void do_oop(oop* p) { do_oop_work(p); }
6850 void do_oop(narrowOop* p) { do_oop_work(p); }
6851 };
6852
6853 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6854 CollectedHeap::register_nmethod(nm);
6855
6856 guarantee(nm != NULL, "sanity");
6857 RegisterNMethodOopClosure reg_cl(this, nm);
6858 nm->oops_do(®_cl);
6859 }
6860
6861 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6862 CollectedHeap::unregister_nmethod(nm);
6863
6864 guarantee(nm != NULL, "sanity");
6865 UnregisterNMethodOopClosure reg_cl(this, nm);
6866 nm->oops_do(®_cl, true);
6867 }
6868
6869 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6870 public:
6871 bool doHeapRegion(HeapRegion *hr) {
6872 assert(!hr->isHumongous(),
6873 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6874 HR_FORMAT_PARAMS(hr)));
6875 hr->migrate_strong_code_roots();
6876 return false;
6877 }
6878 };
6879
6880 void G1CollectedHeap::migrate_strong_code_roots() {
6881 MigrateCodeRootsHeapRegionClosure cl;
6882 double migrate_start = os::elapsedTime();
6883 collection_set_iterate(&cl);
6884 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6885 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6886 }
6887
6888 void G1CollectedHeap::purge_code_root_memory() {
6889 double purge_start = os::elapsedTime();
6890 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6891 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6892 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6893 }
6894
6895 // Mark all the code roots that point into regions *not* in the
6896 // collection set.
6897 //
6898 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6899 // walking the the code roots lists of regions not in the collection
6900 // set. Suppose we have an nmethod (M) that points to objects in two
6901 // separate regions - one in the collection set (R1) and one not (R2).
6902 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6903 // nmethod M when walking the code roots for R1. When we come to scan
6904 // the code roots for R2, we would see that M is already marked and it
6905 // would be skipped and the objects in R2 that are referenced from M
6906 // would not be evacuated.
6907
6908 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6909
6910 class MarkStrongCodeRootOopClosure: public OopClosure {
6911 ConcurrentMark* _cm;
6912 HeapRegion* _hr;
6913 uint _worker_id;
6914
6915 template <class T> void do_oop_work(T* p) {
6916 T heap_oop = oopDesc::load_heap_oop(p);
6917 if (!oopDesc::is_null(heap_oop)) {
6918 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6919 // Only mark objects in the region (which is assumed
6920 // to be not in the collection set).
6921 if (_hr->is_in(obj)) {
6922 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6923 }
6924 }
6925 }
6926
6927 public:
6928 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6929 _cm(cm), _hr(hr), _worker_id(worker_id) {
6930 assert(!_hr->in_collection_set(), "sanity");
6931 }
6932
6933 void do_oop(narrowOop* p) { do_oop_work(p); }
6934 void do_oop(oop* p) { do_oop_work(p); }
6935 };
6936
6937 MarkStrongCodeRootOopClosure _oop_cl;
6938
6939 public:
6940 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6941 _oop_cl(cm, hr, worker_id) {}
6942
6943 void do_code_blob(CodeBlob* cb) {
6944 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6945 if (nm != NULL) {
6946 nm->oops_do(&_oop_cl);
6947 }
6948 }
6949 };
6950
6951 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6952 G1CollectedHeap* _g1h;
6953 uint _worker_id;
6954
6955 public:
6956 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6957 _g1h(g1h), _worker_id(worker_id) {}
6958
6959 bool doHeapRegion(HeapRegion *hr) {
6960 HeapRegionRemSet* hrrs = hr->rem_set();
6961 if (hr->continuesHumongous()) {
6962 // Code roots should never be attached to a continuation of a humongous region
6963 assert(hrrs->strong_code_roots_list_length() == 0,
6964 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6965 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6966 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6967 hrrs->strong_code_roots_list_length()));
6968 return false;
6969 }
6970
6971 if (hr->in_collection_set()) {
6972 // Don't mark code roots into regions in the collection set here.
6973 // They will be marked when we scan them.
6974 return false;
6975 }
6976
6977 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6978 hr->strong_code_roots_do(&cb_cl);
6979 return false;
6980 }
6981 };
6982
6983 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6984 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6985 if (G1CollectedHeap::use_parallel_gc_threads()) {
6986 heap_region_par_iterate_chunked(&cl,
6987 worker_id,
6988 workers()->active_workers(),
6989 HeapRegion::ParMarkRootClaimValue);
6990 } else {
6991 heap_region_iterate(&cl);
6992 }
6993 }
6994
6995 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6996 G1CollectedHeap* _g1h;
6997
6998 public:
6999 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7000 _g1h(g1h) {}
7001
7002 void do_code_blob(CodeBlob* cb) {
7003 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7004 if (nm == NULL) {
7005 return;
7006 }
7007
7008 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
7009 _g1h->register_nmethod(nm);
7010 }
7011 }
7012 };
7013
7014 void G1CollectedHeap::rebuild_strong_code_roots() {
7015 RebuildStrongCodeRootClosure blob_cl(this);
7016 CodeCache::blobs_do(&blob_cl);
7017 }