1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/stringTable.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "gc_implementation/g1/bufferingOopClosure.hpp"
35 #include "gc_implementation/g1/concurrentG1Refine.hpp"
36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
40 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
41 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
42 #include "gc_implementation/g1/g1EvacFailure.hpp"
43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
44 #include "gc_implementation/g1/g1Log.hpp"
45 #include "gc_implementation/g1/g1MarkSweep.hpp"
46 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
47 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
48 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
49 #include "gc_implementation/g1/g1RemSet.inline.hpp"
50 #include "gc_implementation/g1/g1StringDedup.hpp"
51 #include "gc_implementation/g1/g1YCTypes.hpp"
52 #include "gc_implementation/g1/heapRegion.inline.hpp"
53 #include "gc_implementation/g1/heapRegionRemSet.hpp"
54 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
55 #include "gc_implementation/g1/vm_operations_g1.hpp"
56 #include "gc_implementation/shared/gcHeapSummary.hpp"
57 #include "gc_implementation/shared/gcTimer.hpp"
58 #include "gc_implementation/shared/gcTrace.hpp"
59 #include "gc_implementation/shared/gcTraceTime.hpp"
60 #include "gc_implementation/shared/isGCActiveMark.hpp"
61 #include "memory/allocation.hpp"
62 #include "memory/gcLocker.inline.hpp"
63 #include "memory/generationSpec.hpp"
64 #include "memory/iterator.hpp"
65 #include "memory/referenceProcessor.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "oops/oop.pcgc.inline.hpp"
68 #include "runtime/atomic.inline.hpp"
69 #include "runtime/orderAccess.inline.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "utilities/globalDefinitions.hpp"
72
73 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
74
75 // turn it on so that the contents of the young list (scan-only /
76 // to-be-collected) are printed at "strategic" points before / during
77 // / after the collection --- this is useful for debugging
78 #define YOUNG_LIST_VERBOSE 0
79 // CURRENT STATUS
80 // This file is under construction. Search for "FIXME".
81
82 // INVARIANTS/NOTES
83 //
84 // All allocation activity covered by the G1CollectedHeap interface is
85 // serialized by acquiring the HeapLock. This happens in mem_allocate
86 // and allocate_new_tlab, which are the "entry" points to the
87 // allocation code from the rest of the JVM. (Note that this does not
88 // apply to TLAB allocation, which is not part of this interface: it
89 // is done by clients of this interface.)
90
91 // Notes on implementation of parallelism in different tasks.
92 //
93 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
94 // The number of GC workers is passed to heap_region_par_iterate_chunked().
95 // It does use run_task() which sets _n_workers in the task.
96 // G1ParTask executes g1_process_roots() ->
97 // SharedHeap::process_roots() which calls eventually to
98 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
99 // SequentialSubTasksDone. SharedHeap::process_roots() also
100 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
101 //
102
103 // Local to this file.
104
105 class RefineCardTableEntryClosure: public CardTableEntryClosure {
106 bool _concurrent;
107 public:
108 RefineCardTableEntryClosure() : _concurrent(true) { }
109
110 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
111 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
112 // This path is executed by the concurrent refine or mutator threads,
113 // concurrently, and so we do not care if card_ptr contains references
114 // that point into the collection set.
115 assert(!oops_into_cset, "should be");
116
117 if (_concurrent && SuspendibleThreadSet::should_yield()) {
118 // Caller will actually yield.
119 return false;
120 }
121 // Otherwise, we finished successfully; return true.
122 return true;
123 }
124
125 void set_concurrent(bool b) { _concurrent = b; }
126 };
127
128
129 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
130 size_t _num_processed;
131 CardTableModRefBS* _ctbs;
132 int _histo[256];
133
134 public:
135 ClearLoggedCardTableEntryClosure() :
136 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
137 {
138 for (int i = 0; i < 256; i++) _histo[i] = 0;
139 }
140
141 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
142 unsigned char* ujb = (unsigned char*)card_ptr;
143 int ind = (int)(*ujb);
144 _histo[ind]++;
145
146 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
147 _num_processed++;
148
149 return true;
150 }
151
152 size_t num_processed() { return _num_processed; }
153
154 void print_histo() {
155 gclog_or_tty->print_cr("Card table value histogram:");
156 for (int i = 0; i < 256; i++) {
157 if (_histo[i] != 0) {
158 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
159 }
160 }
161 }
162 };
163
164 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
165 private:
166 size_t _num_processed;
167
168 public:
169 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
170
171 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
172 *card_ptr = CardTableModRefBS::dirty_card_val();
173 _num_processed++;
174 return true;
175 }
176
177 size_t num_processed() const { return _num_processed; }
178 };
179
180 YoungList::YoungList(G1CollectedHeap* g1h) :
181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
183 guarantee(check_list_empty(false), "just making sure...");
184 }
185
186 void YoungList::push_region(HeapRegion *hr) {
187 assert(!hr->is_young(), "should not already be young");
188 assert(hr->get_next_young_region() == NULL, "cause it should!");
189
190 hr->set_next_young_region(_head);
191 _head = hr;
192
193 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
194 ++_length;
195 }
196
197 void YoungList::add_survivor_region(HeapRegion* hr) {
198 assert(hr->is_survivor(), "should be flagged as survivor region");
199 assert(hr->get_next_young_region() == NULL, "cause it should!");
200
201 hr->set_next_young_region(_survivor_head);
202 if (_survivor_head == NULL) {
203 _survivor_tail = hr;
204 }
205 _survivor_head = hr;
206 ++_survivor_length;
207 }
208
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 list->set_not_young();
215 list = next;
216 }
217 }
218
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
221
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
225
226 empty_list(_survivor_head);
227 _survivor_head = NULL;
228 _survivor_tail = NULL;
229 _survivor_length = 0;
230
231 _last_sampled_rs_lengths = 0;
232
233 assert(check_list_empty(false), "just making sure...");
234 }
235
236 bool YoungList::check_list_well_formed() {
237 bool ret = true;
238
239 uint length = 0;
240 HeapRegion* curr = _head;
241 HeapRegion* last = NULL;
242 while (curr != NULL) {
243 if (!curr->is_young()) {
244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
245 "incorrectly tagged (y: %d, surv: %d)",
246 curr->bottom(), curr->end(),
247 curr->is_young(), curr->is_survivor());
248 ret = false;
249 }
250 ++length;
251 last = curr;
252 curr = curr->get_next_young_region();
253 }
254 ret = ret && (length == _length);
255
256 if (!ret) {
257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
258 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
259 length, _length);
260 }
261
262 return ret;
263 }
264
265 bool YoungList::check_list_empty(bool check_sample) {
266 bool ret = true;
267
268 if (_length != 0) {
269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
270 _length);
271 ret = false;
272 }
273 if (check_sample && _last_sampled_rs_lengths != 0) {
274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
275 ret = false;
276 }
277 if (_head != NULL) {
278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
279 ret = false;
280 }
281 if (!ret) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
283 }
284
285 return ret;
286 }
287
288 void
289 YoungList::rs_length_sampling_init() {
290 _sampled_rs_lengths = 0;
291 _curr = _head;
292 }
293
294 bool
295 YoungList::rs_length_sampling_more() {
296 return _curr != NULL;
297 }
298
299 void
300 YoungList::rs_length_sampling_next() {
301 assert( _curr != NULL, "invariant" );
302 size_t rs_length = _curr->rem_set()->occupied();
303
304 _sampled_rs_lengths += rs_length;
305
306 // The current region may not yet have been added to the
307 // incremental collection set (it gets added when it is
308 // retired as the current allocation region).
309 if (_curr->in_collection_set()) {
310 // Update the collection set policy information for this region
311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
312 }
313
314 _curr = _curr->get_next_young_region();
315 if (_curr == NULL) {
316 _last_sampled_rs_lengths = _sampled_rs_lengths;
317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
318 }
319 }
320
321 void
322 YoungList::reset_auxilary_lists() {
323 guarantee( is_empty(), "young list should be empty" );
324 assert(check_list_well_formed(), "young list should be well formed");
325
326 // Add survivor regions to SurvRateGroup.
327 _g1h->g1_policy()->note_start_adding_survivor_regions();
328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
329
330 int young_index_in_cset = 0;
331 for (HeapRegion* curr = _survivor_head;
332 curr != NULL;
333 curr = curr->get_next_young_region()) {
334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
335
336 // The region is a non-empty survivor so let's add it to
337 // the incremental collection set for the next evacuation
338 // pause.
339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
340 young_index_in_cset += 1;
341 }
342 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
343 _g1h->g1_policy()->note_stop_adding_survivor_regions();
344
345 _head = _survivor_head;
346 _length = _survivor_length;
347 if (_survivor_head != NULL) {
348 assert(_survivor_tail != NULL, "cause it shouldn't be");
349 assert(_survivor_length > 0, "invariant");
350 _survivor_tail->set_next_young_region(NULL);
351 }
352
353 // Don't clear the survivor list handles until the start of
354 // the next evacuation pause - we need it in order to re-tag
355 // the survivor regions from this evacuation pause as 'young'
356 // at the start of the next.
357
358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
359
360 assert(check_list_well_formed(), "young list should be well formed");
361 }
362
363 void YoungList::print() {
364 HeapRegion* lists[] = {_head, _survivor_head};
365 const char* names[] = {"YOUNG", "SURVIVOR"};
366
367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
369 HeapRegion *curr = lists[list];
370 if (curr == NULL)
371 gclog_or_tty->print_cr(" empty");
372 while (curr != NULL) {
373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
374 HR_FORMAT_PARAMS(curr),
375 curr->prev_top_at_mark_start(),
376 curr->next_top_at_mark_start(),
377 curr->age_in_surv_rate_group_cond());
378 curr = curr->get_next_young_region();
379 }
380 }
381
382 gclog_or_tty->cr();
383 }
384
385 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
386 OtherRegionsTable::invalidate(start_idx, num_regions);
387 }
388
389 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
390 reset_from_card_cache(start_idx, num_regions);
391 }
392
393 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
394 {
395 // Claim the right to put the region on the dirty cards region list
396 // by installing a self pointer.
397 HeapRegion* next = hr->get_next_dirty_cards_region();
398 if (next == NULL) {
399 HeapRegion* res = (HeapRegion*)
400 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
401 NULL);
402 if (res == NULL) {
403 HeapRegion* head;
404 do {
405 // Put the region to the dirty cards region list.
406 head = _dirty_cards_region_list;
407 next = (HeapRegion*)
408 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
409 if (next == head) {
410 assert(hr->get_next_dirty_cards_region() == hr,
411 "hr->get_next_dirty_cards_region() != hr");
412 if (next == NULL) {
413 // The last region in the list points to itself.
414 hr->set_next_dirty_cards_region(hr);
415 } else {
416 hr->set_next_dirty_cards_region(next);
417 }
418 }
419 } while (next != head);
420 }
421 }
422 }
423
424 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
425 {
426 HeapRegion* head;
427 HeapRegion* hr;
428 do {
429 head = _dirty_cards_region_list;
430 if (head == NULL) {
431 return NULL;
432 }
433 HeapRegion* new_head = head->get_next_dirty_cards_region();
434 if (head == new_head) {
435 // The last region.
436 new_head = NULL;
437 }
438 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
439 head);
440 } while (hr != head);
441 assert(hr != NULL, "invariant");
442 hr->set_next_dirty_cards_region(NULL);
443 return hr;
444 }
445
446 #ifdef ASSERT
447 // A region is added to the collection set as it is retired
448 // so an address p can point to a region which will be in the
449 // collection set but has not yet been retired. This method
450 // therefore is only accurate during a GC pause after all
451 // regions have been retired. It is used for debugging
452 // to check if an nmethod has references to objects that can
453 // be move during a partial collection. Though it can be
454 // inaccurate, it is sufficient for G1 because the conservative
455 // implementation of is_scavengable() for G1 will indicate that
456 // all nmethods must be scanned during a partial collection.
457 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
458 if (p == NULL) {
459 return false;
460 }
461 return heap_region_containing(p)->in_collection_set();
462 }
463 #endif
464
465 // Returns true if the reference points to an object that
466 // can move in an incremental collection.
467 bool G1CollectedHeap::is_scavengable(const void* p) {
468 HeapRegion* hr = heap_region_containing(p);
469 return !hr->isHumongous();
470 }
471
472 void G1CollectedHeap::check_ct_logs_at_safepoint() {
473 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
474 CardTableModRefBS* ct_bs = g1_barrier_set();
475
476 // Count the dirty cards at the start.
477 CountNonCleanMemRegionClosure count1(this);
478 ct_bs->mod_card_iterate(&count1);
479 int orig_count = count1.n();
480
481 // First clear the logged cards.
482 ClearLoggedCardTableEntryClosure clear;
483 dcqs.apply_closure_to_all_completed_buffers(&clear);
484 dcqs.iterate_closure_all_threads(&clear, false);
485 clear.print_histo();
486
487 // Now ensure that there's no dirty cards.
488 CountNonCleanMemRegionClosure count2(this);
489 ct_bs->mod_card_iterate(&count2);
490 if (count2.n() != 0) {
491 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
492 count2.n(), orig_count);
493 }
494 guarantee(count2.n() == 0, "Card table should be clean.");
495
496 RedirtyLoggedCardTableEntryClosure redirty;
497 dcqs.apply_closure_to_all_completed_buffers(&redirty);
498 dcqs.iterate_closure_all_threads(&redirty, false);
499 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
500 clear.num_processed(), orig_count);
501 guarantee(redirty.num_processed() == clear.num_processed(),
502 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
503 redirty.num_processed(), clear.num_processed()));
504
505 CountNonCleanMemRegionClosure count3(this);
506 ct_bs->mod_card_iterate(&count3);
507 if (count3.n() != orig_count) {
508 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
509 orig_count, count3.n());
510 guarantee(count3.n() >= orig_count, "Should have restored them all.");
511 }
512 }
513
514 // Private class members.
515
516 G1CollectedHeap* G1CollectedHeap::_g1h;
517
518 // Private methods.
519
520 HeapRegion*
521 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
522 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
523 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
524 if (!_secondary_free_list.is_empty()) {
525 if (G1ConcRegionFreeingVerbose) {
526 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
527 "secondary_free_list has %u entries",
528 _secondary_free_list.length());
529 }
530 // It looks as if there are free regions available on the
531 // secondary_free_list. Let's move them to the free_list and try
532 // again to allocate from it.
533 append_secondary_free_list();
534
535 assert(_hrs.num_free_regions() > 0, "if the secondary_free_list was not "
536 "empty we should have moved at least one entry to the free_list");
537 HeapRegion* res = _hrs.allocate_free_region(is_old);
538 if (G1ConcRegionFreeingVerbose) {
539 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
540 "allocated "HR_FORMAT" from secondary_free_list",
541 HR_FORMAT_PARAMS(res));
542 }
543 return res;
544 }
545
546 // Wait here until we get notified either when (a) there are no
547 // more free regions coming or (b) some regions have been moved on
548 // the secondary_free_list.
549 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
550 }
551
552 if (G1ConcRegionFreeingVerbose) {
553 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
554 "could not allocate from secondary_free_list");
555 }
556 return NULL;
557 }
558
559 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
560 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
561 "the only time we use this to allocate a humongous region is "
562 "when we are allocating a single humongous region");
563
564 HeapRegion* res;
565 if (G1StressConcRegionFreeing) {
566 if (!_secondary_free_list.is_empty()) {
567 if (G1ConcRegionFreeingVerbose) {
568 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
569 "forced to look at the secondary_free_list");
570 }
571 res = new_region_try_secondary_free_list(is_old);
572 if (res != NULL) {
573 return res;
574 }
575 }
576 }
577
578 res = _hrs.allocate_free_region(is_old);
579
580 if (res == NULL) {
581 if (G1ConcRegionFreeingVerbose) {
582 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
583 "res == NULL, trying the secondary_free_list");
584 }
585 res = new_region_try_secondary_free_list(is_old);
586 }
587 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
588 // Currently, only attempts to allocate GC alloc regions set
589 // do_expand to true. So, we should only reach here during a
590 // safepoint. If this assumption changes we might have to
591 // reconsider the use of _expand_heap_after_alloc_failure.
592 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
593
594 ergo_verbose1(ErgoHeapSizing,
595 "attempt heap expansion",
596 ergo_format_reason("region allocation request failed")
597 ergo_format_byte("allocation request"),
598 word_size * HeapWordSize);
599 if (expand(word_size * HeapWordSize)) {
600 // Given that expand() succeeded in expanding the heap, and we
601 // always expand the heap by an amount aligned to the heap
602 // region size, the free list should in theory not be empty.
603 // In either case allocate_free_region() will check for NULL.
604 res = _hrs.allocate_free_region(is_old);
605 } else {
606 _expand_heap_after_alloc_failure = false;
607 }
608 }
609 return res;
610 }
611
612 HeapWord*
613 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
614 uint num_regions,
615 size_t word_size) {
616 assert(first != G1_NO_HRS_INDEX, "pre-condition");
617 assert(isHumongous(word_size), "word_size should be humongous");
618 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
619
620 // Index of last region in the series + 1.
621 uint last = first + num_regions;
622
623 // We need to initialize the region(s) we just discovered. This is
624 // a bit tricky given that it can happen concurrently with
625 // refinement threads refining cards on these regions and
626 // potentially wanting to refine the BOT as they are scanning
627 // those cards (this can happen shortly after a cleanup; see CR
628 // 6991377). So we have to set up the region(s) carefully and in
629 // a specific order.
630
631 // The word size sum of all the regions we will allocate.
632 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
633 assert(word_size <= word_size_sum, "sanity");
634
635 // This will be the "starts humongous" region.
636 HeapRegion* first_hr = region_at(first);
637 // The header of the new object will be placed at the bottom of
638 // the first region.
639 HeapWord* new_obj = first_hr->bottom();
640 // This will be the new end of the first region in the series that
641 // should also match the end of the last region in the series.
642 HeapWord* new_end = new_obj + word_size_sum;
643 // This will be the new top of the first region that will reflect
644 // this allocation.
645 HeapWord* new_top = new_obj + word_size;
646
647 // First, we need to zero the header of the space that we will be
648 // allocating. When we update top further down, some refinement
649 // threads might try to scan the region. By zeroing the header we
650 // ensure that any thread that will try to scan the region will
651 // come across the zero klass word and bail out.
652 //
653 // NOTE: It would not have been correct to have used
654 // CollectedHeap::fill_with_object() and make the space look like
655 // an int array. The thread that is doing the allocation will
656 // later update the object header to a potentially different array
657 // type and, for a very short period of time, the klass and length
658 // fields will be inconsistent. This could cause a refinement
659 // thread to calculate the object size incorrectly.
660 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
661
662 // We will set up the first region as "starts humongous". This
663 // will also update the BOT covering all the regions to reflect
664 // that there is a single object that starts at the bottom of the
665 // first region.
666 first_hr->set_startsHumongous(new_top, new_end);
667
668 // Then, if there are any, we will set up the "continues
669 // humongous" regions.
670 HeapRegion* hr = NULL;
671 for (uint i = first + 1; i < last; ++i) {
672 hr = region_at(i);
673 hr->set_continuesHumongous(first_hr);
674 }
675 // If we have "continues humongous" regions (hr != NULL), then the
676 // end of the last one should match new_end.
677 assert(hr == NULL || hr->end() == new_end, "sanity");
678
679 // Up to this point no concurrent thread would have been able to
680 // do any scanning on any region in this series. All the top
681 // fields still point to bottom, so the intersection between
682 // [bottom,top] and [card_start,card_end] will be empty. Before we
683 // update the top fields, we'll do a storestore to make sure that
684 // no thread sees the update to top before the zeroing of the
685 // object header and the BOT initialization.
686 OrderAccess::storestore();
687
688 // Now that the BOT and the object header have been initialized,
689 // we can update top of the "starts humongous" region.
690 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
691 "new_top should be in this region");
692 first_hr->set_top(new_top);
693 if (_hr_printer.is_active()) {
694 HeapWord* bottom = first_hr->bottom();
695 HeapWord* end = first_hr->orig_end();
696 if ((first + 1) == last) {
697 // the series has a single humongous region
698 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
699 } else {
700 // the series has more than one humongous regions
701 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
702 }
703 }
704
705 // Now, we will update the top fields of the "continues humongous"
706 // regions. The reason we need to do this is that, otherwise,
707 // these regions would look empty and this will confuse parts of
708 // G1. For example, the code that looks for a consecutive number
709 // of empty regions will consider them empty and try to
710 // re-allocate them. We can extend is_empty() to also include
711 // !continuesHumongous(), but it is easier to just update the top
712 // fields here. The way we set top for all regions (i.e., top ==
713 // end for all regions but the last one, top == new_top for the
714 // last one) is actually used when we will free up the humongous
715 // region in free_humongous_region().
716 hr = NULL;
717 for (uint i = first + 1; i < last; ++i) {
718 hr = region_at(i);
719 if ((i + 1) == last) {
720 // last continues humongous region
721 assert(hr->bottom() < new_top && new_top <= hr->end(),
722 "new_top should fall on this region");
723 hr->set_top(new_top);
724 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
725 } else {
726 // not last one
727 assert(new_top > hr->end(), "new_top should be above this region");
728 hr->set_top(hr->end());
729 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
730 }
731 }
732 // If we have continues humongous regions (hr != NULL), then the
733 // end of the last one should match new_end and its top should
734 // match new_top.
735 assert(hr == NULL ||
736 (hr->end() == new_end && hr->top() == new_top), "sanity");
737 check_bitmaps("Humongous Region Allocation", first_hr);
738
739 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
740 _summary_bytes_used += first_hr->used();
741 _humongous_set.add(first_hr);
742
743 return new_obj;
744 }
745
746 // If could fit into free regions w/o expansion, try.
747 // Otherwise, if can expand, do so.
748 // Otherwise, if using ex regions might help, try with ex given back.
749 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
750 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
751
752 verify_region_sets_optional();
753
754 uint first = G1_NO_HRS_INDEX;
755 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
756
757 if (obj_regions == 1) {
758 // Only one region to allocate, try to use a fast path by directly allocating
759 // from the free lists. Do not try to expand here, we will potentially do that
760 // later.
761 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
762 if (hr != NULL) {
763 first = hr->hrs_index();
764 }
765 } else {
766 // We can't allocate humongous regions spanning more than one region while
767 // cleanupComplete() is running, since some of the regions we find to be
768 // empty might not yet be added to the free list. It is not straightforward
769 // to know in which list they are on so that we can remove them. We only
770 // need to do this if we need to allocate more than one region to satisfy the
771 // current humongous allocation request. If we are only allocating one region
772 // we use the one-region region allocation code (see above), that already
773 // potentially waits for regions from the secondary free list.
774 wait_while_free_regions_coming();
775 append_secondary_free_list_if_not_empty_with_lock();
776
777 // Policy: Try only empty regions (i.e. already committed first). Maybe we
778 // are lucky enough to find some.
779 first = _hrs.find_contiguous_only_empty(obj_regions);
780 if (first != G1_NO_HRS_INDEX) {
781 _hrs.allocate_free_regions_starting_at(first, obj_regions);
782 }
783 }
784
785 if (first == G1_NO_HRS_INDEX) {
786 // Policy: We could not find enough regions for the humongous object in the
787 // free list. Look through the heap to find a mix of free and uncommitted regions.
788 // If so, try expansion.
789 first = _hrs.find_contiguous_empty_or_unavailable(obj_regions);
790 if (first != G1_NO_HRS_INDEX) {
791 // We found something. Make sure these regions are committed, i.e. expand
792 // the heap. Alternatively we could do a defragmentation GC.
793 ergo_verbose1(ErgoHeapSizing,
794 "attempt heap expansion",
795 ergo_format_reason("humongous allocation request failed")
796 ergo_format_byte("allocation request"),
797 word_size * HeapWordSize);
798
799 _hrs.expand_at(first, obj_regions);
800 g1_policy()->record_new_heap_size(num_regions());
801
802 #ifdef ASSERT
803 for (uint i = first; i < first + obj_regions; ++i) {
804 HeapRegion* hr = region_at(i);
805 assert(hr->is_empty(), "sanity");
806 assert(is_on_master_free_list(hr), "sanity");
807 }
808 #endif
809 _hrs.allocate_free_regions_starting_at(first, obj_regions);
810 } else {
811 // Policy: Potentially trigger a defragmentation GC.
812 }
813 }
814
815 HeapWord* result = NULL;
816 if (first != G1_NO_HRS_INDEX) {
817 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
818 assert(result != NULL, "it should always return a valid result");
819
820 // A successful humongous object allocation changes the used space
821 // information of the old generation so we need to recalculate the
822 // sizes and update the jstat counters here.
823 g1mm()->update_sizes();
824 }
825
826 verify_region_sets_optional();
827
828 return result;
829 }
830
831 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
832 assert_heap_not_locked_and_not_at_safepoint();
833 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
834
835 unsigned int dummy_gc_count_before;
836 int dummy_gclocker_retry_count = 0;
837 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
838 }
839
840 HeapWord*
841 G1CollectedHeap::mem_allocate(size_t word_size,
842 bool* gc_overhead_limit_was_exceeded) {
843 assert_heap_not_locked_and_not_at_safepoint();
844
845 // Loop until the allocation is satisfied, or unsatisfied after GC.
846 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
847 unsigned int gc_count_before;
848
849 HeapWord* result = NULL;
850 if (!isHumongous(word_size)) {
851 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
852 } else {
853 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
854 }
855 if (result != NULL) {
856 return result;
857 }
858
859 // Create the garbage collection operation...
860 VM_G1CollectForAllocation op(gc_count_before, word_size);
861 // ...and get the VM thread to execute it.
862 VMThread::execute(&op);
863
864 if (op.prologue_succeeded() && op.pause_succeeded()) {
865 // If the operation was successful we'll return the result even
866 // if it is NULL. If the allocation attempt failed immediately
867 // after a Full GC, it's unlikely we'll be able to allocate now.
868 HeapWord* result = op.result();
869 if (result != NULL && !isHumongous(word_size)) {
870 // Allocations that take place on VM operations do not do any
871 // card dirtying and we have to do it here. We only have to do
872 // this for non-humongous allocations, though.
873 dirty_young_block(result, word_size);
874 }
875 return result;
876 } else {
877 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
878 return NULL;
879 }
880 assert(op.result() == NULL,
881 "the result should be NULL if the VM op did not succeed");
882 }
883
884 // Give a warning if we seem to be looping forever.
885 if ((QueuedAllocationWarningCount > 0) &&
886 (try_count % QueuedAllocationWarningCount == 0)) {
887 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
888 }
889 }
890
891 ShouldNotReachHere();
892 return NULL;
893 }
894
895 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
896 unsigned int *gc_count_before_ret,
897 int* gclocker_retry_count_ret) {
898 // Make sure you read the note in attempt_allocation_humongous().
899
900 assert_heap_not_locked_and_not_at_safepoint();
901 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
902 "be called for humongous allocation requests");
903
904 // We should only get here after the first-level allocation attempt
905 // (attempt_allocation()) failed to allocate.
906
907 // We will loop until a) we manage to successfully perform the
908 // allocation or b) we successfully schedule a collection which
909 // fails to perform the allocation. b) is the only case when we'll
910 // return NULL.
911 HeapWord* result = NULL;
912 for (int try_count = 1; /* we'll return */; try_count += 1) {
913 bool should_try_gc;
914 unsigned int gc_count_before;
915
916 {
917 MutexLockerEx x(Heap_lock);
918
919 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
920 false /* bot_updates */);
921 if (result != NULL) {
922 return result;
923 }
924
925 // If we reach here, attempt_allocation_locked() above failed to
926 // allocate a new region. So the mutator alloc region should be NULL.
927 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
928
929 if (GC_locker::is_active_and_needs_gc()) {
930 if (g1_policy()->can_expand_young_list()) {
931 // No need for an ergo verbose message here,
932 // can_expand_young_list() does this when it returns true.
933 result = _mutator_alloc_region.attempt_allocation_force(word_size,
934 false /* bot_updates */);
935 if (result != NULL) {
936 return result;
937 }
938 }
939 should_try_gc = false;
940 } else {
941 // The GCLocker may not be active but the GCLocker initiated
942 // GC may not yet have been performed (GCLocker::needs_gc()
943 // returns true). In this case we do not try this GC and
944 // wait until the GCLocker initiated GC is performed, and
945 // then retry the allocation.
946 if (GC_locker::needs_gc()) {
947 should_try_gc = false;
948 } else {
949 // Read the GC count while still holding the Heap_lock.
950 gc_count_before = total_collections();
951 should_try_gc = true;
952 }
953 }
954 }
955
956 if (should_try_gc) {
957 bool succeeded;
958 result = do_collection_pause(word_size, gc_count_before, &succeeded,
959 GCCause::_g1_inc_collection_pause);
960 if (result != NULL) {
961 assert(succeeded, "only way to get back a non-NULL result");
962 return result;
963 }
964
965 if (succeeded) {
966 // If we get here we successfully scheduled a collection which
967 // failed to allocate. No point in trying to allocate
968 // further. We'll just return NULL.
969 MutexLockerEx x(Heap_lock);
970 *gc_count_before_ret = total_collections();
971 return NULL;
972 }
973 } else {
974 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
975 MutexLockerEx x(Heap_lock);
976 *gc_count_before_ret = total_collections();
977 return NULL;
978 }
979 // The GCLocker is either active or the GCLocker initiated
980 // GC has not yet been performed. Stall until it is and
981 // then retry the allocation.
982 GC_locker::stall_until_clear();
983 (*gclocker_retry_count_ret) += 1;
984 }
985
986 // We can reach here if we were unsuccessful in scheduling a
987 // collection (because another thread beat us to it) or if we were
988 // stalled due to the GC locker. In either can we should retry the
989 // allocation attempt in case another thread successfully
990 // performed a collection and reclaimed enough space. We do the
991 // first attempt (without holding the Heap_lock) here and the
992 // follow-on attempt will be at the start of the next loop
993 // iteration (after taking the Heap_lock).
994 result = _mutator_alloc_region.attempt_allocation(word_size,
995 false /* bot_updates */);
996 if (result != NULL) {
997 return result;
998 }
999
1000 // Give a warning if we seem to be looping forever.
1001 if ((QueuedAllocationWarningCount > 0) &&
1002 (try_count % QueuedAllocationWarningCount == 0)) {
1003 warning("G1CollectedHeap::attempt_allocation_slow() "
1004 "retries %d times", try_count);
1005 }
1006 }
1007
1008 ShouldNotReachHere();
1009 return NULL;
1010 }
1011
1012 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1013 unsigned int * gc_count_before_ret,
1014 int* gclocker_retry_count_ret) {
1015 // The structure of this method has a lot of similarities to
1016 // attempt_allocation_slow(). The reason these two were not merged
1017 // into a single one is that such a method would require several "if
1018 // allocation is not humongous do this, otherwise do that"
1019 // conditional paths which would obscure its flow. In fact, an early
1020 // version of this code did use a unified method which was harder to
1021 // follow and, as a result, it had subtle bugs that were hard to
1022 // track down. So keeping these two methods separate allows each to
1023 // be more readable. It will be good to keep these two in sync as
1024 // much as possible.
1025
1026 assert_heap_not_locked_and_not_at_safepoint();
1027 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1028 "should only be called for humongous allocations");
1029
1030 // Humongous objects can exhaust the heap quickly, so we should check if we
1031 // need to start a marking cycle at each humongous object allocation. We do
1032 // the check before we do the actual allocation. The reason for doing it
1033 // before the allocation is that we avoid having to keep track of the newly
1034 // allocated memory while we do a GC.
1035 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1036 word_size)) {
1037 collect(GCCause::_g1_humongous_allocation);
1038 }
1039
1040 // We will loop until a) we manage to successfully perform the
1041 // allocation or b) we successfully schedule a collection which
1042 // fails to perform the allocation. b) is the only case when we'll
1043 // return NULL.
1044 HeapWord* result = NULL;
1045 for (int try_count = 1; /* we'll return */; try_count += 1) {
1046 bool should_try_gc;
1047 unsigned int gc_count_before;
1048
1049 {
1050 MutexLockerEx x(Heap_lock);
1051
1052 // Given that humongous objects are not allocated in young
1053 // regions, we'll first try to do the allocation without doing a
1054 // collection hoping that there's enough space in the heap.
1055 result = humongous_obj_allocate(word_size);
1056 if (result != NULL) {
1057 return result;
1058 }
1059
1060 if (GC_locker::is_active_and_needs_gc()) {
1061 should_try_gc = false;
1062 } else {
1063 // The GCLocker may not be active but the GCLocker initiated
1064 // GC may not yet have been performed (GCLocker::needs_gc()
1065 // returns true). In this case we do not try this GC and
1066 // wait until the GCLocker initiated GC is performed, and
1067 // then retry the allocation.
1068 if (GC_locker::needs_gc()) {
1069 should_try_gc = false;
1070 } else {
1071 // Read the GC count while still holding the Heap_lock.
1072 gc_count_before = total_collections();
1073 should_try_gc = true;
1074 }
1075 }
1076 }
1077
1078 if (should_try_gc) {
1079 // If we failed to allocate the humongous object, we should try to
1080 // do a collection pause (if we're allowed) in case it reclaims
1081 // enough space for the allocation to succeed after the pause.
1082
1083 bool succeeded;
1084 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1085 GCCause::_g1_humongous_allocation);
1086 if (result != NULL) {
1087 assert(succeeded, "only way to get back a non-NULL result");
1088 return result;
1089 }
1090
1091 if (succeeded) {
1092 // If we get here we successfully scheduled a collection which
1093 // failed to allocate. No point in trying to allocate
1094 // further. We'll just return NULL.
1095 MutexLockerEx x(Heap_lock);
1096 *gc_count_before_ret = total_collections();
1097 return NULL;
1098 }
1099 } else {
1100 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1101 MutexLockerEx x(Heap_lock);
1102 *gc_count_before_ret = total_collections();
1103 return NULL;
1104 }
1105 // The GCLocker is either active or the GCLocker initiated
1106 // GC has not yet been performed. Stall until it is and
1107 // then retry the allocation.
1108 GC_locker::stall_until_clear();
1109 (*gclocker_retry_count_ret) += 1;
1110 }
1111
1112 // We can reach here if we were unsuccessful in scheduling a
1113 // collection (because another thread beat us to it) or if we were
1114 // stalled due to the GC locker. In either can we should retry the
1115 // allocation attempt in case another thread successfully
1116 // performed a collection and reclaimed enough space. Give a
1117 // warning if we seem to be looping forever.
1118
1119 if ((QueuedAllocationWarningCount > 0) &&
1120 (try_count % QueuedAllocationWarningCount == 0)) {
1121 warning("G1CollectedHeap::attempt_allocation_humongous() "
1122 "retries %d times", try_count);
1123 }
1124 }
1125
1126 ShouldNotReachHere();
1127 return NULL;
1128 }
1129
1130 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1131 bool expect_null_mutator_alloc_region) {
1132 assert_at_safepoint(true /* should_be_vm_thread */);
1133 assert(_mutator_alloc_region.get() == NULL ||
1134 !expect_null_mutator_alloc_region,
1135 "the current alloc region was unexpectedly found to be non-NULL");
1136
1137 if (!isHumongous(word_size)) {
1138 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1139 false /* bot_updates */);
1140 } else {
1141 HeapWord* result = humongous_obj_allocate(word_size);
1142 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1143 g1_policy()->set_initiate_conc_mark_if_possible();
1144 }
1145 return result;
1146 }
1147
1148 ShouldNotReachHere();
1149 }
1150
1151 class PostMCRemSetClearClosure: public HeapRegionClosure {
1152 G1CollectedHeap* _g1h;
1153 ModRefBarrierSet* _mr_bs;
1154 public:
1155 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1156 _g1h(g1h), _mr_bs(mr_bs) {}
1157
1158 bool doHeapRegion(HeapRegion* r) {
1159 HeapRegionRemSet* hrrs = r->rem_set();
1160
1161 if (r->continuesHumongous()) {
1162 // We'll assert that the strong code root list and RSet is empty
1163 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1164 assert(hrrs->occupied() == 0, "RSet should be empty");
1165 return false;
1166 }
1167
1168 _g1h->reset_gc_time_stamps(r);
1169 hrrs->clear();
1170 // You might think here that we could clear just the cards
1171 // corresponding to the used region. But no: if we leave a dirty card
1172 // in a region we might allocate into, then it would prevent that card
1173 // from being enqueued, and cause it to be missed.
1174 // Re: the performance cost: we shouldn't be doing full GC anyway!
1175 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1176
1177 return false;
1178 }
1179 };
1180
1181 void G1CollectedHeap::clear_rsets_post_compaction() {
1182 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1183 heap_region_iterate(&rs_clear);
1184 }
1185
1186 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1187 G1CollectedHeap* _g1h;
1188 UpdateRSOopClosure _cl;
1189 int _worker_i;
1190 public:
1191 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1192 _cl(g1->g1_rem_set(), worker_i),
1193 _worker_i(worker_i),
1194 _g1h(g1)
1195 { }
1196
1197 bool doHeapRegion(HeapRegion* r) {
1198 if (!r->continuesHumongous()) {
1199 _cl.set_from(r);
1200 r->oop_iterate(&_cl);
1201 }
1202 return false;
1203 }
1204 };
1205
1206 class ParRebuildRSTask: public AbstractGangTask {
1207 G1CollectedHeap* _g1;
1208 public:
1209 ParRebuildRSTask(G1CollectedHeap* g1)
1210 : AbstractGangTask("ParRebuildRSTask"),
1211 _g1(g1)
1212 { }
1213
1214 void work(uint worker_id) {
1215 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1216 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1217 _g1->workers()->active_workers(),
1218 HeapRegion::RebuildRSClaimValue);
1219 }
1220 };
1221
1222 class PostCompactionPrinterClosure: public HeapRegionClosure {
1223 private:
1224 G1HRPrinter* _hr_printer;
1225 public:
1226 bool doHeapRegion(HeapRegion* hr) {
1227 assert(!hr->is_young(), "not expecting to find young regions");
1228 // We only generate output for non-empty regions.
1229 if (!hr->is_empty()) {
1230 if (!hr->isHumongous()) {
1231 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1232 } else if (hr->startsHumongous()) {
1233 if (hr->region_num() == 1) {
1234 // single humongous region
1235 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1236 } else {
1237 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1238 }
1239 } else {
1240 assert(hr->continuesHumongous(), "only way to get here");
1241 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1242 }
1243 }
1244 return false;
1245 }
1246
1247 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1248 : _hr_printer(hr_printer) { }
1249 };
1250
1251 void G1CollectedHeap::print_hrs_post_compaction() {
1252 PostCompactionPrinterClosure cl(hr_printer());
1253 heap_region_iterate(&cl);
1254 }
1255
1256 bool G1CollectedHeap::do_collection(bool explicit_gc,
1257 bool clear_all_soft_refs,
1258 size_t word_size) {
1259 assert_at_safepoint(true /* should_be_vm_thread */);
1260
1261 if (GC_locker::check_active_before_gc()) {
1262 return false;
1263 }
1264
1265 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1266 gc_timer->register_gc_start();
1267
1268 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1269 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1270
1271 SvcGCMarker sgcm(SvcGCMarker::FULL);
1272 ResourceMark rm;
1273
1274 print_heap_before_gc();
1275 trace_heap_before_gc(gc_tracer);
1276
1277 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1278
1279 verify_region_sets_optional();
1280
1281 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1282 collector_policy()->should_clear_all_soft_refs();
1283
1284 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1285
1286 {
1287 IsGCActiveMark x;
1288
1289 // Timing
1290 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1291 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1292 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1293
1294 {
1295 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1296 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1297 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1298
1299 double start = os::elapsedTime();
1300 g1_policy()->record_full_collection_start();
1301
1302 // Note: When we have a more flexible GC logging framework that
1303 // allows us to add optional attributes to a GC log record we
1304 // could consider timing and reporting how long we wait in the
1305 // following two methods.
1306 wait_while_free_regions_coming();
1307 // If we start the compaction before the CM threads finish
1308 // scanning the root regions we might trip them over as we'll
1309 // be moving objects / updating references. So let's wait until
1310 // they are done. By telling them to abort, they should complete
1311 // early.
1312 _cm->root_regions()->abort();
1313 _cm->root_regions()->wait_until_scan_finished();
1314 append_secondary_free_list_if_not_empty_with_lock();
1315
1316 gc_prologue(true);
1317 increment_total_collections(true /* full gc */);
1318 increment_old_marking_cycles_started();
1319
1320 assert(used() == recalculate_used(), "Should be equal");
1321
1322 verify_before_gc();
1323
1324 check_bitmaps("Full GC Start");
1325 pre_full_gc_dump(gc_timer);
1326
1327 COMPILER2_PRESENT(DerivedPointerTable::clear());
1328
1329 // Disable discovery and empty the discovered lists
1330 // for the CM ref processor.
1331 ref_processor_cm()->disable_discovery();
1332 ref_processor_cm()->abandon_partial_discovery();
1333 ref_processor_cm()->verify_no_references_recorded();
1334
1335 // Abandon current iterations of concurrent marking and concurrent
1336 // refinement, if any are in progress. We have to do this before
1337 // wait_until_scan_finished() below.
1338 concurrent_mark()->abort();
1339
1340 // Make sure we'll choose a new allocation region afterwards.
1341 release_mutator_alloc_region();
1342 abandon_gc_alloc_regions();
1343 g1_rem_set()->cleanupHRRS();
1344
1345 // We should call this after we retire any currently active alloc
1346 // regions so that all the ALLOC / RETIRE events are generated
1347 // before the start GC event.
1348 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1349
1350 // We may have added regions to the current incremental collection
1351 // set between the last GC or pause and now. We need to clear the
1352 // incremental collection set and then start rebuilding it afresh
1353 // after this full GC.
1354 abandon_collection_set(g1_policy()->inc_cset_head());
1355 g1_policy()->clear_incremental_cset();
1356 g1_policy()->stop_incremental_cset_building();
1357
1358 tear_down_region_sets(false /* free_list_only */);
1359 g1_policy()->set_gcs_are_young(true);
1360
1361 // See the comments in g1CollectedHeap.hpp and
1362 // G1CollectedHeap::ref_processing_init() about
1363 // how reference processing currently works in G1.
1364
1365 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1366 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1367
1368 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1369 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1370
1371 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1372 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1373
1374 // Do collection work
1375 {
1376 HandleMark hm; // Discard invalid handles created during gc
1377 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1378 }
1379
1380 assert(num_free_regions() == 0, "we should not have added any free regions");
1381 rebuild_region_sets(false /* free_list_only */);
1382
1383 // Enqueue any discovered reference objects that have
1384 // not been removed from the discovered lists.
1385 ref_processor_stw()->enqueue_discovered_references();
1386
1387 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1388
1389 MemoryService::track_memory_usage();
1390
1391 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1392 ref_processor_stw()->verify_no_references_recorded();
1393
1394 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1395 ClassLoaderDataGraph::purge();
1396 MetaspaceAux::verify_metrics();
1397
1398 // Note: since we've just done a full GC, concurrent
1399 // marking is no longer active. Therefore we need not
1400 // re-enable reference discovery for the CM ref processor.
1401 // That will be done at the start of the next marking cycle.
1402 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1403 ref_processor_cm()->verify_no_references_recorded();
1404
1405 reset_gc_time_stamp();
1406 // Since everything potentially moved, we will clear all remembered
1407 // sets, and clear all cards. Later we will rebuild remembered
1408 // sets. We will also reset the GC time stamps of the regions.
1409 clear_rsets_post_compaction();
1410 check_gc_time_stamps();
1411
1412 // Resize the heap if necessary.
1413 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1414
1415 if (_hr_printer.is_active()) {
1416 // We should do this after we potentially resize the heap so
1417 // that all the COMMIT / UNCOMMIT events are generated before
1418 // the end GC event.
1419
1420 print_hrs_post_compaction();
1421 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1422 }
1423
1424 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1425 if (hot_card_cache->use_cache()) {
1426 hot_card_cache->reset_card_counts();
1427 hot_card_cache->reset_hot_cache();
1428 }
1429
1430 // Rebuild remembered sets of all regions.
1431 if (G1CollectedHeap::use_parallel_gc_threads()) {
1432 uint n_workers =
1433 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1434 workers()->active_workers(),
1435 Threads::number_of_non_daemon_threads());
1436 assert(UseDynamicNumberOfGCThreads ||
1437 n_workers == workers()->total_workers(),
1438 "If not dynamic should be using all the workers");
1439 workers()->set_active_workers(n_workers);
1440 // Set parallel threads in the heap (_n_par_threads) only
1441 // before a parallel phase and always reset it to 0 after
1442 // the phase so that the number of parallel threads does
1443 // no get carried forward to a serial phase where there
1444 // may be code that is "possibly_parallel".
1445 set_par_threads(n_workers);
1446
1447 ParRebuildRSTask rebuild_rs_task(this);
1448 assert(check_heap_region_claim_values(
1449 HeapRegion::InitialClaimValue), "sanity check");
1450 assert(UseDynamicNumberOfGCThreads ||
1451 workers()->active_workers() == workers()->total_workers(),
1452 "Unless dynamic should use total workers");
1453 // Use the most recent number of active workers
1454 assert(workers()->active_workers() > 0,
1455 "Active workers not properly set");
1456 set_par_threads(workers()->active_workers());
1457 workers()->run_task(&rebuild_rs_task);
1458 set_par_threads(0);
1459 assert(check_heap_region_claim_values(
1460 HeapRegion::RebuildRSClaimValue), "sanity check");
1461 reset_heap_region_claim_values();
1462 } else {
1463 RebuildRSOutOfRegionClosure rebuild_rs(this);
1464 heap_region_iterate(&rebuild_rs);
1465 }
1466
1467 // Rebuild the strong code root lists for each region
1468 rebuild_strong_code_roots();
1469
1470 if (true) { // FIXME
1471 MetaspaceGC::compute_new_size();
1472 }
1473
1474 #ifdef TRACESPINNING
1475 ParallelTaskTerminator::print_termination_counts();
1476 #endif
1477
1478 // Discard all rset updates
1479 JavaThread::dirty_card_queue_set().abandon_logs();
1480 assert(!G1DeferredRSUpdate
1481 || (G1DeferredRSUpdate &&
1482 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1483
1484 _young_list->reset_sampled_info();
1485 // At this point there should be no regions in the
1486 // entire heap tagged as young.
1487 assert(check_young_list_empty(true /* check_heap */),
1488 "young list should be empty at this point");
1489
1490 // Update the number of full collections that have been completed.
1491 increment_old_marking_cycles_completed(false /* concurrent */);
1492
1493 _hrs.verify_optional();
1494 verify_region_sets_optional();
1495
1496 verify_after_gc();
1497
1498 // Clear the previous marking bitmap, if needed for bitmap verification.
1499 // Note we cannot do this when we clear the next marking bitmap in
1500 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1501 // objects marked during a full GC against the previous bitmap.
1502 // But we need to clear it before calling check_bitmaps below since
1503 // the full GC has compacted objects and updated TAMS but not updated
1504 // the prev bitmap.
1505 if (G1VerifyBitmaps) {
1506 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1507 }
1508 check_bitmaps("Full GC End");
1509
1510 // Start a new incremental collection set for the next pause
1511 assert(g1_policy()->collection_set() == NULL, "must be");
1512 g1_policy()->start_incremental_cset_building();
1513
1514 clear_cset_fast_test();
1515
1516 init_mutator_alloc_region();
1517
1518 double end = os::elapsedTime();
1519 g1_policy()->record_full_collection_end();
1520
1521 if (G1Log::fine()) {
1522 g1_policy()->print_heap_transition();
1523 }
1524
1525 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1526 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1527 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1528 // before any GC notifications are raised.
1529 g1mm()->update_sizes();
1530
1531 gc_epilogue(true);
1532 }
1533
1534 if (G1Log::finer()) {
1535 g1_policy()->print_detailed_heap_transition(true /* full */);
1536 }
1537
1538 print_heap_after_gc();
1539 trace_heap_after_gc(gc_tracer);
1540
1541 post_full_gc_dump(gc_timer);
1542
1543 gc_timer->register_gc_end();
1544 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1545 }
1546
1547 return true;
1548 }
1549
1550 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1551 // do_collection() will return whether it succeeded in performing
1552 // the GC. Currently, there is no facility on the
1553 // do_full_collection() API to notify the caller than the collection
1554 // did not succeed (e.g., because it was locked out by the GC
1555 // locker). So, right now, we'll ignore the return value.
1556 bool dummy = do_collection(true, /* explicit_gc */
1557 clear_all_soft_refs,
1558 0 /* word_size */);
1559 }
1560
1561 // This code is mostly copied from TenuredGeneration.
1562 void
1563 G1CollectedHeap::
1564 resize_if_necessary_after_full_collection(size_t word_size) {
1565 // Include the current allocation, if any, and bytes that will be
1566 // pre-allocated to support collections, as "used".
1567 const size_t used_after_gc = used();
1568 const size_t capacity_after_gc = capacity();
1569 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1570
1571 // This is enforced in arguments.cpp.
1572 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1573 "otherwise the code below doesn't make sense");
1574
1575 // We don't have floating point command-line arguments
1576 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1577 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1578 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1579 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1580
1581 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1582 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1583
1584 // We have to be careful here as these two calculations can overflow
1585 // 32-bit size_t's.
1586 double used_after_gc_d = (double) used_after_gc;
1587 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1588 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1589
1590 // Let's make sure that they are both under the max heap size, which
1591 // by default will make them fit into a size_t.
1592 double desired_capacity_upper_bound = (double) max_heap_size;
1593 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1594 desired_capacity_upper_bound);
1595 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1596 desired_capacity_upper_bound);
1597
1598 // We can now safely turn them into size_t's.
1599 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1600 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1601
1602 // This assert only makes sense here, before we adjust them
1603 // with respect to the min and max heap size.
1604 assert(minimum_desired_capacity <= maximum_desired_capacity,
1605 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1606 "maximum_desired_capacity = "SIZE_FORMAT,
1607 minimum_desired_capacity, maximum_desired_capacity));
1608
1609 // Should not be greater than the heap max size. No need to adjust
1610 // it with respect to the heap min size as it's a lower bound (i.e.,
1611 // we'll try to make the capacity larger than it, not smaller).
1612 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1613 // Should not be less than the heap min size. No need to adjust it
1614 // with respect to the heap max size as it's an upper bound (i.e.,
1615 // we'll try to make the capacity smaller than it, not greater).
1616 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1617
1618 if (capacity_after_gc < minimum_desired_capacity) {
1619 // Don't expand unless it's significant
1620 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1621 ergo_verbose4(ErgoHeapSizing,
1622 "attempt heap expansion",
1623 ergo_format_reason("capacity lower than "
1624 "min desired capacity after Full GC")
1625 ergo_format_byte("capacity")
1626 ergo_format_byte("occupancy")
1627 ergo_format_byte_perc("min desired capacity"),
1628 capacity_after_gc, used_after_gc,
1629 minimum_desired_capacity, (double) MinHeapFreeRatio);
1630 expand(expand_bytes);
1631
1632 // No expansion, now see if we want to shrink
1633 } else if (capacity_after_gc > maximum_desired_capacity) {
1634 // Capacity too large, compute shrinking size
1635 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1636 ergo_verbose4(ErgoHeapSizing,
1637 "attempt heap shrinking",
1638 ergo_format_reason("capacity higher than "
1639 "max desired capacity after Full GC")
1640 ergo_format_byte("capacity")
1641 ergo_format_byte("occupancy")
1642 ergo_format_byte_perc("max desired capacity"),
1643 capacity_after_gc, used_after_gc,
1644 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1645 shrink(shrink_bytes);
1646 }
1647 }
1648
1649
1650 HeapWord*
1651 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1652 bool* succeeded) {
1653 assert_at_safepoint(true /* should_be_vm_thread */);
1654
1655 *succeeded = true;
1656 // Let's attempt the allocation first.
1657 HeapWord* result =
1658 attempt_allocation_at_safepoint(word_size,
1659 false /* expect_null_mutator_alloc_region */);
1660 if (result != NULL) {
1661 assert(*succeeded, "sanity");
1662 return result;
1663 }
1664
1665 // In a G1 heap, we're supposed to keep allocation from failing by
1666 // incremental pauses. Therefore, at least for now, we'll favor
1667 // expansion over collection. (This might change in the future if we can
1668 // do something smarter than full collection to satisfy a failed alloc.)
1669 result = expand_and_allocate(word_size);
1670 if (result != NULL) {
1671 assert(*succeeded, "sanity");
1672 return result;
1673 }
1674
1675 // Expansion didn't work, we'll try to do a Full GC.
1676 bool gc_succeeded = do_collection(false, /* explicit_gc */
1677 false, /* clear_all_soft_refs */
1678 word_size);
1679 if (!gc_succeeded) {
1680 *succeeded = false;
1681 return NULL;
1682 }
1683
1684 // Retry the allocation
1685 result = attempt_allocation_at_safepoint(word_size,
1686 true /* expect_null_mutator_alloc_region */);
1687 if (result != NULL) {
1688 assert(*succeeded, "sanity");
1689 return result;
1690 }
1691
1692 // Then, try a Full GC that will collect all soft references.
1693 gc_succeeded = do_collection(false, /* explicit_gc */
1694 true, /* clear_all_soft_refs */
1695 word_size);
1696 if (!gc_succeeded) {
1697 *succeeded = false;
1698 return NULL;
1699 }
1700
1701 // Retry the allocation once more
1702 result = attempt_allocation_at_safepoint(word_size,
1703 true /* expect_null_mutator_alloc_region */);
1704 if (result != NULL) {
1705 assert(*succeeded, "sanity");
1706 return result;
1707 }
1708
1709 assert(!collector_policy()->should_clear_all_soft_refs(),
1710 "Flag should have been handled and cleared prior to this point");
1711
1712 // What else? We might try synchronous finalization later. If the total
1713 // space available is large enough for the allocation, then a more
1714 // complete compaction phase than we've tried so far might be
1715 // appropriate.
1716 assert(*succeeded, "sanity");
1717 return NULL;
1718 }
1719
1720 // Attempting to expand the heap sufficiently
1721 // to support an allocation of the given "word_size". If
1722 // successful, perform the allocation and return the address of the
1723 // allocated block, or else "NULL".
1724
1725 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1726 assert_at_safepoint(true /* should_be_vm_thread */);
1727
1728 verify_region_sets_optional();
1729
1730 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1731 ergo_verbose1(ErgoHeapSizing,
1732 "attempt heap expansion",
1733 ergo_format_reason("allocation request failed")
1734 ergo_format_byte("allocation request"),
1735 word_size * HeapWordSize);
1736 if (expand(expand_bytes)) {
1737 _hrs.verify_optional();
1738 verify_region_sets_optional();
1739 return attempt_allocation_at_safepoint(word_size,
1740 false /* expect_null_mutator_alloc_region */);
1741 }
1742 return NULL;
1743 }
1744
1745 bool G1CollectedHeap::expand(size_t expand_bytes) {
1746 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1747 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1748 HeapRegion::GrainBytes);
1749 ergo_verbose2(ErgoHeapSizing,
1750 "expand the heap",
1751 ergo_format_byte("requested expansion amount")
1752 ergo_format_byte("attempted expansion amount"),
1753 expand_bytes, aligned_expand_bytes);
1754
1755 if (is_maximal_no_gc()) {
1756 ergo_verbose0(ErgoHeapSizing,
1757 "did not expand the heap",
1758 ergo_format_reason("heap already fully expanded"));
1759 return false;
1760 }
1761
1762 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1763 assert(regions_to_expand > 0, "Must expand by at least one region");
1764
1765 uint expanded_by = _hrs.expand_by(regions_to_expand);
1766
1767 if (expanded_by > 0) {
1768 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1769 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1770 g1_policy()->record_new_heap_size(num_regions());
1771 } else {
1772 ergo_verbose0(ErgoHeapSizing,
1773 "did not expand the heap",
1774 ergo_format_reason("heap expansion operation failed"));
1775 // The expansion of the virtual storage space was unsuccessful.
1776 // Let's see if it was because we ran out of swap.
1777 if (G1ExitOnExpansionFailure &&
1778 _hrs.available() >= regions_to_expand) {
1779 // We had head room...
1780 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1781 }
1782 }
1783 return regions_to_expand > 0;
1784 }
1785
1786 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1787 size_t aligned_shrink_bytes =
1788 ReservedSpace::page_align_size_down(shrink_bytes);
1789 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1790 HeapRegion::GrainBytes);
1791 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1792
1793 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1794 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1795
1796 ergo_verbose3(ErgoHeapSizing,
1797 "shrink the heap",
1798 ergo_format_byte("requested shrinking amount")
1799 ergo_format_byte("aligned shrinking amount")
1800 ergo_format_byte("attempted shrinking amount"),
1801 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1802 if (num_regions_removed > 0) {
1803 g1_policy()->record_new_heap_size(num_regions());
1804 } else {
1805 ergo_verbose0(ErgoHeapSizing,
1806 "did not shrink the heap",
1807 ergo_format_reason("heap shrinking operation failed"));
1808 }
1809 }
1810
1811 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1812 verify_region_sets_optional();
1813
1814 // We should only reach here at the end of a Full GC which means we
1815 // should not not be holding to any GC alloc regions. The method
1816 // below will make sure of that and do any remaining clean up.
1817 abandon_gc_alloc_regions();
1818
1819 // Instead of tearing down / rebuilding the free lists here, we
1820 // could instead use the remove_all_pending() method on free_list to
1821 // remove only the ones that we need to remove.
1822 tear_down_region_sets(true /* free_list_only */);
1823 shrink_helper(shrink_bytes);
1824 rebuild_region_sets(true /* free_list_only */);
1825
1826 _hrs.verify_optional();
1827 verify_region_sets_optional();
1828 }
1829
1830 // Public methods.
1831
1832 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1833 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1834 #endif // _MSC_VER
1835
1836
1837 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1838 SharedHeap(policy_),
1839 _g1_policy(policy_),
1840 _dirty_card_queue_set(false),
1841 _into_cset_dirty_card_queue_set(false),
1842 _is_alive_closure_cm(this),
1843 _is_alive_closure_stw(this),
1844 _ref_processor_cm(NULL),
1845 _ref_processor_stw(NULL),
1846 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1847 _bot_shared(NULL),
1848 _evac_failure_scan_stack(NULL),
1849 _mark_in_progress(false),
1850 _cg1r(NULL), _summary_bytes_used(0),
1851 _g1mm(NULL),
1852 _refine_cte_cl(NULL),
1853 _full_collection(false),
1854 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1855 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1856 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1857 _humongous_is_live(),
1858 _has_humongous_reclaim_candidates(false),
1859 _free_regions_coming(false),
1860 _young_list(new YoungList(this)),
1861 _gc_time_stamp(0),
1862 _retained_old_gc_alloc_region(NULL),
1863 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1864 _old_plab_stats(OldPLABSize, PLABWeight),
1865 _expand_heap_after_alloc_failure(true),
1866 _surviving_young_words(NULL),
1867 _old_marking_cycles_started(0),
1868 _old_marking_cycles_completed(0),
1869 _concurrent_cycle_started(false),
1870 _in_cset_fast_test(),
1871 _dirty_cards_region_list(NULL),
1872 _worker_cset_start_region(NULL),
1873 _worker_cset_start_region_time_stamp(NULL),
1874 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1875 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1876 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1877 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1878
1879 _g1h = this;
1880 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1881 vm_exit_during_initialization("Failed necessary allocation.");
1882 }
1883
1884 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1885
1886 int n_queues = MAX2((int)ParallelGCThreads, 1);
1887 _task_queues = new RefToScanQueueSet(n_queues);
1888
1889 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1890 assert(n_rem_sets > 0, "Invariant.");
1891
1892 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1893 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1894 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1895
1896 for (int i = 0; i < n_queues; i++) {
1897 RefToScanQueue* q = new RefToScanQueue();
1898 q->initialize();
1899 _task_queues->register_queue(i, q);
1900 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1901 }
1902 clear_cset_start_regions();
1903
1904 // Initialize the G1EvacuationFailureALot counters and flags.
1905 NOT_PRODUCT(reset_evacuation_should_fail();)
1906
1907 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1908 }
1909
1910 jint G1CollectedHeap::initialize() {
1911 CollectedHeap::pre_initialize();
1912 os::enable_vtime();
1913
1914 G1Log::init();
1915
1916 // Necessary to satisfy locking discipline assertions.
1917
1918 MutexLocker x(Heap_lock);
1919
1920 // We have to initialize the printer before committing the heap, as
1921 // it will be used then.
1922 _hr_printer.set_active(G1PrintHeapRegions);
1923
1924 // While there are no constraints in the GC code that HeapWordSize
1925 // be any particular value, there are multiple other areas in the
1926 // system which believe this to be true (e.g. oop->object_size in some
1927 // cases incorrectly returns the size in wordSize units rather than
1928 // HeapWordSize).
1929 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1930
1931 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1932 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1933 size_t heap_alignment = collector_policy()->heap_alignment();
1934
1935 // Ensure that the sizes are properly aligned.
1936 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1937 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1938 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1939
1940 _refine_cte_cl = new RefineCardTableEntryClosure();
1941
1942 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1943
1944 // Reserve the maximum.
1945
1946 // When compressed oops are enabled, the preferred heap base
1947 // is calculated by subtracting the requested size from the
1948 // 32Gb boundary and using the result as the base address for
1949 // heap reservation. If the requested size is not aligned to
1950 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1951 // into the ReservedHeapSpace constructor) then the actual
1952 // base of the reserved heap may end up differing from the
1953 // address that was requested (i.e. the preferred heap base).
1954 // If this happens then we could end up using a non-optimal
1955 // compressed oops mode.
1956
1957 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1958 heap_alignment);
1959
1960 // It is important to do this in a way such that concurrent readers can't
1961 // temporarily think something is in the heap. (I've actually seen this
1962 // happen in asserts: DLD.)
1963 _reserved.set_word_size(0);
1964 _reserved.set_start((HeapWord*)heap_rs.base());
1965 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1966
1967 // Create the gen rem set (and barrier set) for the entire reserved region.
1968 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1969 set_barrier_set(rem_set()->bs());
1970 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1971 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1972 return JNI_ENOMEM;
1973 }
1974
1975 // Also create a G1 rem set.
1976 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1977
1978 // Carve out the G1 part of the heap.
1979
1980 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1981 G1RegionToSpaceMapper* heap_storage =
1982 G1RegionToSpaceMapper::create_mapper(g1_rs,
1983 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1984 HeapRegion::GrainBytes,
1985 1,
1986 mtJavaHeap);
1987 heap_storage->set_mapping_changed_listener(&_listener);
1988
1989 // Reserve space for the block offset table. We do not support automatic uncommit
1990 // for the card table at this time. BOT only.
1991 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1992 G1RegionToSpaceMapper* bot_storage =
1993 G1RegionToSpaceMapper::create_mapper(bot_rs,
1994 os::vm_page_size(),
1995 HeapRegion::GrainBytes,
1996 G1BlockOffsetSharedArray::N_bytes,
1997 mtGC);
1998
1999 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2000 G1RegionToSpaceMapper* cardtable_storage =
2001 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
2002 os::vm_page_size(),
2003 HeapRegion::GrainBytes,
2004 G1BlockOffsetSharedArray::N_bytes,
2005 mtGC);
2006
2007 // Reserve space for the card counts table.
2008 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
2009 G1RegionToSpaceMapper* card_counts_storage =
2010 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
2011 os::vm_page_size(),
2012 HeapRegion::GrainBytes,
2013 G1BlockOffsetSharedArray::N_bytes,
2014 mtGC);
2015
2016 // Reserve space for prev and next bitmap.
2017 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2018
2019 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2020 G1RegionToSpaceMapper* prev_bitmap_storage =
2021 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
2022 os::vm_page_size(),
2023 HeapRegion::GrainBytes,
2024 CMBitMap::mark_distance(),
2025 mtGC);
2026
2027 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2028 G1RegionToSpaceMapper* next_bitmap_storage =
2029 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
2030 os::vm_page_size(),
2031 HeapRegion::GrainBytes,
2032 CMBitMap::mark_distance(),
2033 mtGC);
2034
2035 _hrs.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2036 g1_barrier_set()->initialize(cardtable_storage);
2037 // Do later initialization work for concurrent refinement.
2038 _cg1r->init(card_counts_storage);
2039
2040 // 6843694 - ensure that the maximum region index can fit
2041 // in the remembered set structures.
2042 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2043 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2044
2045 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2046 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2047 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2048 "too many cards per region");
2049
2050 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2051
2052 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
2053
2054 _g1h = this;
2055
2056 _in_cset_fast_test.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes);
2057 _humongous_is_live.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes);
2058
2059 // Create the ConcurrentMark data structure and thread.
2060 // (Must do this late, so that "max_regions" is defined.)
2061 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2062 if (_cm == NULL || !_cm->completed_initialization()) {
2063 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2064 return JNI_ENOMEM;
2065 }
2066 _cmThread = _cm->cmThread();
2067
2068 // Initialize the from_card cache structure of HeapRegionRemSet.
2069 HeapRegionRemSet::init_heap(max_regions());
2070
2071 // Now expand into the initial heap size.
2072 if (!expand(init_byte_size)) {
2073 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2074 return JNI_ENOMEM;
2075 }
2076
2077 // Perform any initialization actions delegated to the policy.
2078 g1_policy()->init();
2079
2080 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2081 SATB_Q_FL_lock,
2082 G1SATBProcessCompletedThreshold,
2083 Shared_SATB_Q_lock);
2084
2085 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2086 DirtyCardQ_CBL_mon,
2087 DirtyCardQ_FL_lock,
2088 concurrent_g1_refine()->yellow_zone(),
2089 concurrent_g1_refine()->red_zone(),
2090 Shared_DirtyCardQ_lock);
2091
2092 if (G1DeferredRSUpdate) {
2093 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2094 DirtyCardQ_CBL_mon,
2095 DirtyCardQ_FL_lock,
2096 -1, // never trigger processing
2097 -1, // no limit on length
2098 Shared_DirtyCardQ_lock,
2099 &JavaThread::dirty_card_queue_set());
2100 }
2101
2102 // Initialize the card queue set used to hold cards containing
2103 // references into the collection set.
2104 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2105 DirtyCardQ_CBL_mon,
2106 DirtyCardQ_FL_lock,
2107 -1, // never trigger processing
2108 -1, // no limit on length
2109 Shared_DirtyCardQ_lock,
2110 &JavaThread::dirty_card_queue_set());
2111
2112 // In case we're keeping closure specialization stats, initialize those
2113 // counts and that mechanism.
2114 SpecializationStats::clear();
2115
2116 // Here we allocate the dummy HeapRegion that is required by the
2117 // G1AllocRegion class.
2118 HeapRegion* dummy_region = _hrs.get_dummy_region();
2119
2120 // We'll re-use the same region whether the alloc region will
2121 // require BOT updates or not and, if it doesn't, then a non-young
2122 // region will complain that it cannot support allocations without
2123 // BOT updates. So we'll tag the dummy region as young to avoid that.
2124 dummy_region->set_young();
2125 // Make sure it's full.
2126 dummy_region->set_top(dummy_region->end());
2127 G1AllocRegion::setup(this, dummy_region);
2128
2129 init_mutator_alloc_region();
2130
2131 // Do create of the monitoring and management support so that
2132 // values in the heap have been properly initialized.
2133 _g1mm = new G1MonitoringSupport(this);
2134
2135 G1StringDedup::initialize();
2136
2137 return JNI_OK;
2138 }
2139
2140 void G1CollectedHeap::stop() {
2141 // Stop all concurrent threads. We do this to make sure these threads
2142 // do not continue to execute and access resources (e.g. gclog_or_tty)
2143 // that are destroyed during shutdown.
2144 _cg1r->stop();
2145 _cmThread->stop();
2146 if (G1StringDedup::is_enabled()) {
2147 G1StringDedup::stop();
2148 }
2149 }
2150
2151 void G1CollectedHeap::clear_humongous_is_live_table() {
2152 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2153 _humongous_is_live.clear();
2154 }
2155
2156 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2157 return HeapRegion::max_region_size();
2158 }
2159
2160 void G1CollectedHeap::ref_processing_init() {
2161 // Reference processing in G1 currently works as follows:
2162 //
2163 // * There are two reference processor instances. One is
2164 // used to record and process discovered references
2165 // during concurrent marking; the other is used to
2166 // record and process references during STW pauses
2167 // (both full and incremental).
2168 // * Both ref processors need to 'span' the entire heap as
2169 // the regions in the collection set may be dotted around.
2170 //
2171 // * For the concurrent marking ref processor:
2172 // * Reference discovery is enabled at initial marking.
2173 // * Reference discovery is disabled and the discovered
2174 // references processed etc during remarking.
2175 // * Reference discovery is MT (see below).
2176 // * Reference discovery requires a barrier (see below).
2177 // * Reference processing may or may not be MT
2178 // (depending on the value of ParallelRefProcEnabled
2179 // and ParallelGCThreads).
2180 // * A full GC disables reference discovery by the CM
2181 // ref processor and abandons any entries on it's
2182 // discovered lists.
2183 //
2184 // * For the STW processor:
2185 // * Non MT discovery is enabled at the start of a full GC.
2186 // * Processing and enqueueing during a full GC is non-MT.
2187 // * During a full GC, references are processed after marking.
2188 //
2189 // * Discovery (may or may not be MT) is enabled at the start
2190 // of an incremental evacuation pause.
2191 // * References are processed near the end of a STW evacuation pause.
2192 // * For both types of GC:
2193 // * Discovery is atomic - i.e. not concurrent.
2194 // * Reference discovery will not need a barrier.
2195
2196 SharedHeap::ref_processing_init();
2197 MemRegion mr = reserved_region();
2198
2199 // Concurrent Mark ref processor
2200 _ref_processor_cm =
2201 new ReferenceProcessor(mr, // span
2202 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2203 // mt processing
2204 (int) ParallelGCThreads,
2205 // degree of mt processing
2206 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2207 // mt discovery
2208 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2209 // degree of mt discovery
2210 false,
2211 // Reference discovery is not atomic
2212 &_is_alive_closure_cm);
2213 // is alive closure
2214 // (for efficiency/performance)
2215
2216 // STW ref processor
2217 _ref_processor_stw =
2218 new ReferenceProcessor(mr, // span
2219 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2220 // mt processing
2221 MAX2((int)ParallelGCThreads, 1),
2222 // degree of mt processing
2223 (ParallelGCThreads > 1),
2224 // mt discovery
2225 MAX2((int)ParallelGCThreads, 1),
2226 // degree of mt discovery
2227 true,
2228 // Reference discovery is atomic
2229 &_is_alive_closure_stw);
2230 // is alive closure
2231 // (for efficiency/performance)
2232 }
2233
2234 size_t G1CollectedHeap::capacity() const {
2235 return _hrs.length() * HeapRegion::GrainBytes;
2236 }
2237
2238 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2239 assert(!hr->continuesHumongous(), "pre-condition");
2240 hr->reset_gc_time_stamp();
2241 if (hr->startsHumongous()) {
2242 uint first_index = hr->hrs_index() + 1;
2243 uint last_index = hr->last_hc_index();
2244 for (uint i = first_index; i < last_index; i += 1) {
2245 HeapRegion* chr = region_at(i);
2246 assert(chr->continuesHumongous(), "sanity");
2247 chr->reset_gc_time_stamp();
2248 }
2249 }
2250 }
2251
2252 #ifndef PRODUCT
2253 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2254 private:
2255 unsigned _gc_time_stamp;
2256 bool _failures;
2257
2258 public:
2259 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2260 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2261
2262 virtual bool doHeapRegion(HeapRegion* hr) {
2263 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2264 if (_gc_time_stamp != region_gc_time_stamp) {
2265 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2266 "expected %d", HR_FORMAT_PARAMS(hr),
2267 region_gc_time_stamp, _gc_time_stamp);
2268 _failures = true;
2269 }
2270 return false;
2271 }
2272
2273 bool failures() { return _failures; }
2274 };
2275
2276 void G1CollectedHeap::check_gc_time_stamps() {
2277 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2278 heap_region_iterate(&cl);
2279 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2280 }
2281 #endif // PRODUCT
2282
2283 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2284 DirtyCardQueue* into_cset_dcq,
2285 bool concurrent,
2286 uint worker_i) {
2287 // Clean cards in the hot card cache
2288 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2289 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2290
2291 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2292 int n_completed_buffers = 0;
2293 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2294 n_completed_buffers++;
2295 }
2296 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2297 dcqs.clear_n_completed_buffers();
2298 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2299 }
2300
2301
2302 // Computes the sum of the storage used by the various regions.
2303
2304 size_t G1CollectedHeap::used() const {
2305 assert(Heap_lock->owner() != NULL,
2306 "Should be owned on this thread's behalf.");
2307 size_t result = _summary_bytes_used;
2308 // Read only once in case it is set to NULL concurrently
2309 HeapRegion* hr = _mutator_alloc_region.get();
2310 if (hr != NULL)
2311 result += hr->used();
2312 return result;
2313 }
2314
2315 size_t G1CollectedHeap::used_unlocked() const {
2316 size_t result = _summary_bytes_used;
2317 return result;
2318 }
2319
2320 class SumUsedClosure: public HeapRegionClosure {
2321 size_t _used;
2322 public:
2323 SumUsedClosure() : _used(0) {}
2324 bool doHeapRegion(HeapRegion* r) {
2325 if (!r->continuesHumongous()) {
2326 _used += r->used();
2327 }
2328 return false;
2329 }
2330 size_t result() { return _used; }
2331 };
2332
2333 size_t G1CollectedHeap::recalculate_used() const {
2334 double recalculate_used_start = os::elapsedTime();
2335
2336 SumUsedClosure blk;
2337 heap_region_iterate(&blk);
2338
2339 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2340 return blk.result();
2341 }
2342
2343 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2344 switch (cause) {
2345 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2346 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2347 case GCCause::_g1_humongous_allocation: return true;
2348 default: return false;
2349 }
2350 }
2351
2352 #ifndef PRODUCT
2353 void G1CollectedHeap::allocate_dummy_regions() {
2354 // Let's fill up most of the region
2355 size_t word_size = HeapRegion::GrainWords - 1024;
2356 // And as a result the region we'll allocate will be humongous.
2357 guarantee(isHumongous(word_size), "sanity");
2358
2359 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2360 // Let's use the existing mechanism for the allocation
2361 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2362 if (dummy_obj != NULL) {
2363 MemRegion mr(dummy_obj, word_size);
2364 CollectedHeap::fill_with_object(mr);
2365 } else {
2366 // If we can't allocate once, we probably cannot allocate
2367 // again. Let's get out of the loop.
2368 break;
2369 }
2370 }
2371 }
2372 #endif // !PRODUCT
2373
2374 void G1CollectedHeap::increment_old_marking_cycles_started() {
2375 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2376 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2377 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2378 _old_marking_cycles_started, _old_marking_cycles_completed));
2379
2380 _old_marking_cycles_started++;
2381 }
2382
2383 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2384 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2385
2386 // We assume that if concurrent == true, then the caller is a
2387 // concurrent thread that was joined the Suspendible Thread
2388 // Set. If there's ever a cheap way to check this, we should add an
2389 // assert here.
2390
2391 // Given that this method is called at the end of a Full GC or of a
2392 // concurrent cycle, and those can be nested (i.e., a Full GC can
2393 // interrupt a concurrent cycle), the number of full collections
2394 // completed should be either one (in the case where there was no
2395 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2396 // behind the number of full collections started.
2397
2398 // This is the case for the inner caller, i.e. a Full GC.
2399 assert(concurrent ||
2400 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2401 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2402 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2403 "is inconsistent with _old_marking_cycles_completed = %u",
2404 _old_marking_cycles_started, _old_marking_cycles_completed));
2405
2406 // This is the case for the outer caller, i.e. the concurrent cycle.
2407 assert(!concurrent ||
2408 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2409 err_msg("for outer caller (concurrent cycle): "
2410 "_old_marking_cycles_started = %u "
2411 "is inconsistent with _old_marking_cycles_completed = %u",
2412 _old_marking_cycles_started, _old_marking_cycles_completed));
2413
2414 _old_marking_cycles_completed += 1;
2415
2416 // We need to clear the "in_progress" flag in the CM thread before
2417 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2418 // is set) so that if a waiter requests another System.gc() it doesn't
2419 // incorrectly see that a marking cycle is still in progress.
2420 if (concurrent) {
2421 _cmThread->clear_in_progress();
2422 }
2423
2424 // This notify_all() will ensure that a thread that called
2425 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2426 // and it's waiting for a full GC to finish will be woken up. It is
2427 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2428 FullGCCount_lock->notify_all();
2429 }
2430
2431 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2432 _concurrent_cycle_started = true;
2433 _gc_timer_cm->register_gc_start(start_time);
2434
2435 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2436 trace_heap_before_gc(_gc_tracer_cm);
2437 }
2438
2439 void G1CollectedHeap::register_concurrent_cycle_end() {
2440 if (_concurrent_cycle_started) {
2441 if (_cm->has_aborted()) {
2442 _gc_tracer_cm->report_concurrent_mode_failure();
2443 }
2444
2445 _gc_timer_cm->register_gc_end();
2446 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2447
2448 _concurrent_cycle_started = false;
2449 }
2450 }
2451
2452 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2453 if (_concurrent_cycle_started) {
2454 trace_heap_after_gc(_gc_tracer_cm);
2455 }
2456 }
2457
2458 G1YCType G1CollectedHeap::yc_type() {
2459 bool is_young = g1_policy()->gcs_are_young();
2460 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2461 bool is_during_mark = mark_in_progress();
2462
2463 if (is_initial_mark) {
2464 return InitialMark;
2465 } else if (is_during_mark) {
2466 return DuringMark;
2467 } else if (is_young) {
2468 return Normal;
2469 } else {
2470 return Mixed;
2471 }
2472 }
2473
2474 void G1CollectedHeap::collect(GCCause::Cause cause) {
2475 assert_heap_not_locked();
2476
2477 unsigned int gc_count_before;
2478 unsigned int old_marking_count_before;
2479 bool retry_gc;
2480
2481 do {
2482 retry_gc = false;
2483
2484 {
2485 MutexLocker ml(Heap_lock);
2486
2487 // Read the GC count while holding the Heap_lock
2488 gc_count_before = total_collections();
2489 old_marking_count_before = _old_marking_cycles_started;
2490 }
2491
2492 if (should_do_concurrent_full_gc(cause)) {
2493 // Schedule an initial-mark evacuation pause that will start a
2494 // concurrent cycle. We're setting word_size to 0 which means that
2495 // we are not requesting a post-GC allocation.
2496 VM_G1IncCollectionPause op(gc_count_before,
2497 0, /* word_size */
2498 true, /* should_initiate_conc_mark */
2499 g1_policy()->max_pause_time_ms(),
2500 cause);
2501
2502 VMThread::execute(&op);
2503 if (!op.pause_succeeded()) {
2504 if (old_marking_count_before == _old_marking_cycles_started) {
2505 retry_gc = op.should_retry_gc();
2506 } else {
2507 // A Full GC happened while we were trying to schedule the
2508 // initial-mark GC. No point in starting a new cycle given
2509 // that the whole heap was collected anyway.
2510 }
2511
2512 if (retry_gc) {
2513 if (GC_locker::is_active_and_needs_gc()) {
2514 GC_locker::stall_until_clear();
2515 }
2516 }
2517 }
2518 } else {
2519 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2520 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2521
2522 // Schedule a standard evacuation pause. We're setting word_size
2523 // to 0 which means that we are not requesting a post-GC allocation.
2524 VM_G1IncCollectionPause op(gc_count_before,
2525 0, /* word_size */
2526 false, /* should_initiate_conc_mark */
2527 g1_policy()->max_pause_time_ms(),
2528 cause);
2529 VMThread::execute(&op);
2530 } else {
2531 // Schedule a Full GC.
2532 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2533 VMThread::execute(&op);
2534 }
2535 }
2536 } while (retry_gc);
2537 }
2538
2539 bool G1CollectedHeap::is_in(const void* p) const {
2540 if (_hrs.reserved().contains(p)) {
2541 // Given that we know that p is in the reserved space,
2542 // heap_region_containing_raw() should successfully
2543 // return the containing region.
2544 HeapRegion* hr = heap_region_containing_raw(p);
2545 return hr->is_in(p);
2546 } else {
2547 return false;
2548 }
2549 }
2550
2551 #ifdef ASSERT
2552 bool G1CollectedHeap::is_in_exact(const void* p) const {
2553 bool contains = reserved_region().contains(p);
2554 bool available = _hrs.is_available(addr_to_region((HeapWord*)p));
2555 if (contains && available) {
2556 return true;
2557 } else {
2558 return false;
2559 }
2560 }
2561 #endif
2562
2563 // Iteration functions.
2564
2565 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2566
2567 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2568 ExtendedOopClosure* _cl;
2569 public:
2570 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2571 bool doHeapRegion(HeapRegion* r) {
2572 if (!r->continuesHumongous()) {
2573 r->oop_iterate(_cl);
2574 }
2575 return false;
2576 }
2577 };
2578
2579 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2580 IterateOopClosureRegionClosure blk(cl);
2581 heap_region_iterate(&blk);
2582 }
2583
2584 // Iterates an ObjectClosure over all objects within a HeapRegion.
2585
2586 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2587 ObjectClosure* _cl;
2588 public:
2589 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2590 bool doHeapRegion(HeapRegion* r) {
2591 if (! r->continuesHumongous()) {
2592 r->object_iterate(_cl);
2593 }
2594 return false;
2595 }
2596 };
2597
2598 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2599 IterateObjectClosureRegionClosure blk(cl);
2600 heap_region_iterate(&blk);
2601 }
2602
2603 // Calls a SpaceClosure on a HeapRegion.
2604
2605 class SpaceClosureRegionClosure: public HeapRegionClosure {
2606 SpaceClosure* _cl;
2607 public:
2608 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2609 bool doHeapRegion(HeapRegion* r) {
2610 _cl->do_space(r);
2611 return false;
2612 }
2613 };
2614
2615 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2616 SpaceClosureRegionClosure blk(cl);
2617 heap_region_iterate(&blk);
2618 }
2619
2620 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2621 _hrs.iterate(cl);
2622 }
2623
2624 void
2625 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2626 uint worker_id,
2627 uint num_workers,
2628 jint claim_value) const {
2629 _hrs.par_iterate(cl, worker_id, num_workers, claim_value);
2630 }
2631
2632 void
2633 G1CollectedHeap::heap_region_iterate_range(HeapRegionClosure* cl, uint start, uint end) const {
2634 _hrs.iterate_range(cl, start, end);
2635 }
2636
2637 class ResetClaimValuesClosure: public HeapRegionClosure {
2638 public:
2639 bool doHeapRegion(HeapRegion* r) {
2640 r->set_claim_value(HeapRegion::InitialClaimValue);
2641 return false;
2642 }
2643 };
2644
2645 void G1CollectedHeap::reset_heap_region_claim_values() {
2646 ResetClaimValuesClosure blk;
2647 heap_region_iterate(&blk);
2648 }
2649
2650 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2651 ResetClaimValuesClosure blk;
2652 collection_set_iterate(&blk);
2653 }
2654
2655 #ifdef ASSERT
2656 // This checks whether all regions in the heap have the correct claim
2657 // value. I also piggy-backed on this a check to ensure that the
2658 // humongous_start_region() information on "continues humongous"
2659 // regions is correct.
2660
2661 class CheckClaimValuesClosure : public HeapRegionClosure {
2662 private:
2663 jint _claim_value;
2664 uint _failures;
2665 HeapRegion* _sh_region;
2666
2667 public:
2668 CheckClaimValuesClosure(jint claim_value) :
2669 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2670 bool doHeapRegion(HeapRegion* r) {
2671 if (r->claim_value() != _claim_value) {
2672 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2673 "claim value = %d, should be %d",
2674 HR_FORMAT_PARAMS(r),
2675 r->claim_value(), _claim_value);
2676 ++_failures;
2677 }
2678 if (!r->isHumongous()) {
2679 _sh_region = NULL;
2680 } else if (r->startsHumongous()) {
2681 _sh_region = r;
2682 } else if (r->continuesHumongous()) {
2683 if (r->humongous_start_region() != _sh_region) {
2684 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2685 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2686 HR_FORMAT_PARAMS(r),
2687 r->humongous_start_region(),
2688 _sh_region);
2689 ++_failures;
2690 }
2691 }
2692 return false;
2693 }
2694 uint failures() { return _failures; }
2695 };
2696
2697 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2698 CheckClaimValuesClosure cl(claim_value);
2699 heap_region_iterate(&cl);
2700 return cl.failures() == 0;
2701 }
2702
2703 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2704 private:
2705 jint _claim_value;
2706 uint _failures;
2707
2708 public:
2709 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2710 _claim_value(claim_value), _failures(0) { }
2711
2712 uint failures() { return _failures; }
2713
2714 bool doHeapRegion(HeapRegion* hr) {
2715 assert(hr->in_collection_set(), "how?");
2716 assert(!hr->isHumongous(), "H-region in CSet");
2717 if (hr->claim_value() != _claim_value) {
2718 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2719 "claim value = %d, should be %d",
2720 HR_FORMAT_PARAMS(hr),
2721 hr->claim_value(), _claim_value);
2722 _failures += 1;
2723 }
2724 return false;
2725 }
2726 };
2727
2728 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2729 CheckClaimValuesInCSetHRClosure cl(claim_value);
2730 collection_set_iterate(&cl);
2731 return cl.failures() == 0;
2732 }
2733 #endif // ASSERT
2734
2735 // Clear the cached CSet starting regions and (more importantly)
2736 // the time stamps. Called when we reset the GC time stamp.
2737 void G1CollectedHeap::clear_cset_start_regions() {
2738 assert(_worker_cset_start_region != NULL, "sanity");
2739 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2740
2741 int n_queues = MAX2((int)ParallelGCThreads, 1);
2742 for (int i = 0; i < n_queues; i++) {
2743 _worker_cset_start_region[i] = NULL;
2744 _worker_cset_start_region_time_stamp[i] = 0;
2745 }
2746 }
2747
2748 // Given the id of a worker, obtain or calculate a suitable
2749 // starting region for iterating over the current collection set.
2750 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2751 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2752
2753 HeapRegion* result = NULL;
2754 unsigned gc_time_stamp = get_gc_time_stamp();
2755
2756 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2757 // Cached starting region for current worker was set
2758 // during the current pause - so it's valid.
2759 // Note: the cached starting heap region may be NULL
2760 // (when the collection set is empty).
2761 result = _worker_cset_start_region[worker_i];
2762 assert(result == NULL || result->in_collection_set(), "sanity");
2763 return result;
2764 }
2765
2766 // The cached entry was not valid so let's calculate
2767 // a suitable starting heap region for this worker.
2768
2769 // We want the parallel threads to start their collection
2770 // set iteration at different collection set regions to
2771 // avoid contention.
2772 // If we have:
2773 // n collection set regions
2774 // p threads
2775 // Then thread t will start at region floor ((t * n) / p)
2776
2777 result = g1_policy()->collection_set();
2778 if (G1CollectedHeap::use_parallel_gc_threads()) {
2779 uint cs_size = g1_policy()->cset_region_length();
2780 uint active_workers = workers()->active_workers();
2781 assert(UseDynamicNumberOfGCThreads ||
2782 active_workers == workers()->total_workers(),
2783 "Unless dynamic should use total workers");
2784
2785 uint end_ind = (cs_size * worker_i) / active_workers;
2786 uint start_ind = 0;
2787
2788 if (worker_i > 0 &&
2789 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2790 // Previous workers starting region is valid
2791 // so let's iterate from there
2792 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2793 result = _worker_cset_start_region[worker_i - 1];
2794 }
2795
2796 for (uint i = start_ind; i < end_ind; i++) {
2797 result = result->next_in_collection_set();
2798 }
2799 }
2800
2801 // Note: the calculated starting heap region may be NULL
2802 // (when the collection set is empty).
2803 assert(result == NULL || result->in_collection_set(), "sanity");
2804 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2805 "should be updated only once per pause");
2806 _worker_cset_start_region[worker_i] = result;
2807 OrderAccess::storestore();
2808 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2809 return result;
2810 }
2811
2812 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2813 HeapRegion* r = g1_policy()->collection_set();
2814 while (r != NULL) {
2815 HeapRegion* next = r->next_in_collection_set();
2816 if (cl->doHeapRegion(r)) {
2817 cl->incomplete();
2818 return;
2819 }
2820 r = next;
2821 }
2822 }
2823
2824 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2825 HeapRegionClosure *cl) {
2826 if (r == NULL) {
2827 // The CSet is empty so there's nothing to do.
2828 return;
2829 }
2830
2831 assert(r->in_collection_set(),
2832 "Start region must be a member of the collection set.");
2833 HeapRegion* cur = r;
2834 while (cur != NULL) {
2835 HeapRegion* next = cur->next_in_collection_set();
2836 if (cl->doHeapRegion(cur) && false) {
2837 cl->incomplete();
2838 return;
2839 }
2840 cur = next;
2841 }
2842 cur = g1_policy()->collection_set();
2843 while (cur != r) {
2844 HeapRegion* next = cur->next_in_collection_set();
2845 if (cl->doHeapRegion(cur) && false) {
2846 cl->incomplete();
2847 return;
2848 }
2849 cur = next;
2850 }
2851 }
2852
2853 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2854 HeapRegion* result = _hrs.next_region_in_heap(from);
2855 while (result != NULL && result->isHumongous()) {
2856 result = _hrs.next_region_in_heap(result);
2857 }
2858 return result;
2859 }
2860
2861 Space* G1CollectedHeap::space_containing(const void* addr) const {
2862 return heap_region_containing(addr);
2863 }
2864
2865 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2866 Space* sp = space_containing(addr);
2867 return sp->block_start(addr);
2868 }
2869
2870 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2871 Space* sp = space_containing(addr);
2872 return sp->block_size(addr);
2873 }
2874
2875 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2876 Space* sp = space_containing(addr);
2877 return sp->block_is_obj(addr);
2878 }
2879
2880 bool G1CollectedHeap::supports_tlab_allocation() const {
2881 return true;
2882 }
2883
2884 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2885 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2886 }
2887
2888 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2889 return young_list()->eden_used_bytes();
2890 }
2891
2892 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2893 // must be smaller than the humongous object limit.
2894 size_t G1CollectedHeap::max_tlab_size() const {
2895 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2896 }
2897
2898 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2899 // Return the remaining space in the cur alloc region, but not less than
2900 // the min TLAB size.
2901
2902 // Also, this value can be at most the humongous object threshold,
2903 // since we can't allow tlabs to grow big enough to accommodate
2904 // humongous objects.
2905
2906 HeapRegion* hr = _mutator_alloc_region.get();
2907 size_t max_tlab = max_tlab_size() * wordSize;
2908 if (hr == NULL) {
2909 return max_tlab;
2910 } else {
2911 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2912 }
2913 }
2914
2915 size_t G1CollectedHeap::max_capacity() const {
2916 return _hrs.reserved().byte_size();
2917 }
2918
2919 jlong G1CollectedHeap::millis_since_last_gc() {
2920 // assert(false, "NYI");
2921 return 0;
2922 }
2923
2924 void G1CollectedHeap::prepare_for_verify() {
2925 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2926 ensure_parsability(false);
2927 }
2928 g1_rem_set()->prepare_for_verify();
2929 }
2930
2931 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2932 VerifyOption vo) {
2933 switch (vo) {
2934 case VerifyOption_G1UsePrevMarking:
2935 return hr->obj_allocated_since_prev_marking(obj);
2936 case VerifyOption_G1UseNextMarking:
2937 return hr->obj_allocated_since_next_marking(obj);
2938 case VerifyOption_G1UseMarkWord:
2939 return false;
2940 default:
2941 ShouldNotReachHere();
2942 }
2943 return false; // keep some compilers happy
2944 }
2945
2946 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2947 switch (vo) {
2948 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2949 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2950 case VerifyOption_G1UseMarkWord: return NULL;
2951 default: ShouldNotReachHere();
2952 }
2953 return NULL; // keep some compilers happy
2954 }
2955
2956 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2957 switch (vo) {
2958 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2959 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2960 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2961 default: ShouldNotReachHere();
2962 }
2963 return false; // keep some compilers happy
2964 }
2965
2966 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2967 switch (vo) {
2968 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2969 case VerifyOption_G1UseNextMarking: return "NTAMS";
2970 case VerifyOption_G1UseMarkWord: return "NONE";
2971 default: ShouldNotReachHere();
2972 }
2973 return NULL; // keep some compilers happy
2974 }
2975
2976 class VerifyRootsClosure: public OopClosure {
2977 private:
2978 G1CollectedHeap* _g1h;
2979 VerifyOption _vo;
2980 bool _failures;
2981 public:
2982 // _vo == UsePrevMarking -> use "prev" marking information,
2983 // _vo == UseNextMarking -> use "next" marking information,
2984 // _vo == UseMarkWord -> use mark word from object header.
2985 VerifyRootsClosure(VerifyOption vo) :
2986 _g1h(G1CollectedHeap::heap()),
2987 _vo(vo),
2988 _failures(false) { }
2989
2990 bool failures() { return _failures; }
2991
2992 template <class T> void do_oop_nv(T* p) {
2993 T heap_oop = oopDesc::load_heap_oop(p);
2994 if (!oopDesc::is_null(heap_oop)) {
2995 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2996 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2997 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2998 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2999 if (_vo == VerifyOption_G1UseMarkWord) {
3000 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3001 }
3002 obj->print_on(gclog_or_tty);
3003 _failures = true;
3004 }
3005 }
3006 }
3007
3008 void do_oop(oop* p) { do_oop_nv(p); }
3009 void do_oop(narrowOop* p) { do_oop_nv(p); }
3010 };
3011
3012 class G1VerifyCodeRootOopClosure: public OopClosure {
3013 G1CollectedHeap* _g1h;
3014 OopClosure* _root_cl;
3015 nmethod* _nm;
3016 VerifyOption _vo;
3017 bool _failures;
3018
3019 template <class T> void do_oop_work(T* p) {
3020 // First verify that this root is live
3021 _root_cl->do_oop(p);
3022
3023 if (!G1VerifyHeapRegionCodeRoots) {
3024 // We're not verifying the code roots attached to heap region.
3025 return;
3026 }
3027
3028 // Don't check the code roots during marking verification in a full GC
3029 if (_vo == VerifyOption_G1UseMarkWord) {
3030 return;
3031 }
3032
3033 // Now verify that the current nmethod (which contains p) is
3034 // in the code root list of the heap region containing the
3035 // object referenced by p.
3036
3037 T heap_oop = oopDesc::load_heap_oop(p);
3038 if (!oopDesc::is_null(heap_oop)) {
3039 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3040
3041 // Now fetch the region containing the object
3042 HeapRegion* hr = _g1h->heap_region_containing(obj);
3043 HeapRegionRemSet* hrrs = hr->rem_set();
3044 // Verify that the strong code root list for this region
3045 // contains the nmethod
3046 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3047 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3048 "from nmethod "PTR_FORMAT" not in strong "
3049 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3050 p, _nm, hr->bottom(), hr->end());
3051 _failures = true;
3052 }
3053 }
3054 }
3055
3056 public:
3057 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3058 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3059
3060 void do_oop(oop* p) { do_oop_work(p); }
3061 void do_oop(narrowOop* p) { do_oop_work(p); }
3062
3063 void set_nmethod(nmethod* nm) { _nm = nm; }
3064 bool failures() { return _failures; }
3065 };
3066
3067 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3068 G1VerifyCodeRootOopClosure* _oop_cl;
3069
3070 public:
3071 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3072 _oop_cl(oop_cl) {}
3073
3074 void do_code_blob(CodeBlob* cb) {
3075 nmethod* nm = cb->as_nmethod_or_null();
3076 if (nm != NULL) {
3077 _oop_cl->set_nmethod(nm);
3078 nm->oops_do(_oop_cl);
3079 }
3080 }
3081 };
3082
3083 class YoungRefCounterClosure : public OopClosure {
3084 G1CollectedHeap* _g1h;
3085 int _count;
3086 public:
3087 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3088 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3089 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3090
3091 int count() { return _count; }
3092 void reset_count() { _count = 0; };
3093 };
3094
3095 class VerifyKlassClosure: public KlassClosure {
3096 YoungRefCounterClosure _young_ref_counter_closure;
3097 OopClosure *_oop_closure;
3098 public:
3099 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3100 void do_klass(Klass* k) {
3101 k->oops_do(_oop_closure);
3102
3103 _young_ref_counter_closure.reset_count();
3104 k->oops_do(&_young_ref_counter_closure);
3105 if (_young_ref_counter_closure.count() > 0) {
3106 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3107 }
3108 }
3109 };
3110
3111 class VerifyLivenessOopClosure: public OopClosure {
3112 G1CollectedHeap* _g1h;
3113 VerifyOption _vo;
3114 public:
3115 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3116 _g1h(g1h), _vo(vo)
3117 { }
3118 void do_oop(narrowOop *p) { do_oop_work(p); }
3119 void do_oop( oop *p) { do_oop_work(p); }
3120
3121 template <class T> void do_oop_work(T *p) {
3122 oop obj = oopDesc::load_decode_heap_oop(p);
3123 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3124 "Dead object referenced by a not dead object");
3125 }
3126 };
3127
3128 class VerifyObjsInRegionClosure: public ObjectClosure {
3129 private:
3130 G1CollectedHeap* _g1h;
3131 size_t _live_bytes;
3132 HeapRegion *_hr;
3133 VerifyOption _vo;
3134 public:
3135 // _vo == UsePrevMarking -> use "prev" marking information,
3136 // _vo == UseNextMarking -> use "next" marking information,
3137 // _vo == UseMarkWord -> use mark word from object header.
3138 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3139 : _live_bytes(0), _hr(hr), _vo(vo) {
3140 _g1h = G1CollectedHeap::heap();
3141 }
3142 void do_object(oop o) {
3143 VerifyLivenessOopClosure isLive(_g1h, _vo);
3144 assert(o != NULL, "Huh?");
3145 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3146 // If the object is alive according to the mark word,
3147 // then verify that the marking information agrees.
3148 // Note we can't verify the contra-positive of the
3149 // above: if the object is dead (according to the mark
3150 // word), it may not be marked, or may have been marked
3151 // but has since became dead, or may have been allocated
3152 // since the last marking.
3153 if (_vo == VerifyOption_G1UseMarkWord) {
3154 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3155 }
3156
3157 o->oop_iterate_no_header(&isLive);
3158 if (!_hr->obj_allocated_since_prev_marking(o)) {
3159 size_t obj_size = o->size(); // Make sure we don't overflow
3160 _live_bytes += (obj_size * HeapWordSize);
3161 }
3162 }
3163 }
3164 size_t live_bytes() { return _live_bytes; }
3165 };
3166
3167 class PrintObjsInRegionClosure : public ObjectClosure {
3168 HeapRegion *_hr;
3169 G1CollectedHeap *_g1;
3170 public:
3171 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3172 _g1 = G1CollectedHeap::heap();
3173 };
3174
3175 void do_object(oop o) {
3176 if (o != NULL) {
3177 HeapWord *start = (HeapWord *) o;
3178 size_t word_sz = o->size();
3179 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3180 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3181 (void*) o, word_sz,
3182 _g1->isMarkedPrev(o),
3183 _g1->isMarkedNext(o),
3184 _hr->obj_allocated_since_prev_marking(o));
3185 HeapWord *end = start + word_sz;
3186 HeapWord *cur;
3187 int *val;
3188 for (cur = start; cur < end; cur++) {
3189 val = (int *) cur;
3190 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3191 }
3192 }
3193 }
3194 };
3195
3196 class VerifyRegionClosure: public HeapRegionClosure {
3197 private:
3198 bool _par;
3199 VerifyOption _vo;
3200 bool _failures;
3201 public:
3202 // _vo == UsePrevMarking -> use "prev" marking information,
3203 // _vo == UseNextMarking -> use "next" marking information,
3204 // _vo == UseMarkWord -> use mark word from object header.
3205 VerifyRegionClosure(bool par, VerifyOption vo)
3206 : _par(par),
3207 _vo(vo),
3208 _failures(false) {}
3209
3210 bool failures() {
3211 return _failures;
3212 }
3213
3214 bool doHeapRegion(HeapRegion* r) {
3215 if (!r->continuesHumongous()) {
3216 bool failures = false;
3217 r->verify(_vo, &failures);
3218 if (failures) {
3219 _failures = true;
3220 } else {
3221 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3222 r->object_iterate(¬_dead_yet_cl);
3223 if (_vo != VerifyOption_G1UseNextMarking) {
3224 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3225 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3226 "max_live_bytes "SIZE_FORMAT" "
3227 "< calculated "SIZE_FORMAT,
3228 r->bottom(), r->end(),
3229 r->max_live_bytes(),
3230 not_dead_yet_cl.live_bytes());
3231 _failures = true;
3232 }
3233 } else {
3234 // When vo == UseNextMarking we cannot currently do a sanity
3235 // check on the live bytes as the calculation has not been
3236 // finalized yet.
3237 }
3238 }
3239 }
3240 return false; // stop the region iteration if we hit a failure
3241 }
3242 };
3243
3244 // This is the task used for parallel verification of the heap regions
3245
3246 class G1ParVerifyTask: public AbstractGangTask {
3247 private:
3248 G1CollectedHeap* _g1h;
3249 VerifyOption _vo;
3250 bool _failures;
3251
3252 public:
3253 // _vo == UsePrevMarking -> use "prev" marking information,
3254 // _vo == UseNextMarking -> use "next" marking information,
3255 // _vo == UseMarkWord -> use mark word from object header.
3256 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3257 AbstractGangTask("Parallel verify task"),
3258 _g1h(g1h),
3259 _vo(vo),
3260 _failures(false) { }
3261
3262 bool failures() {
3263 return _failures;
3264 }
3265
3266 void work(uint worker_id) {
3267 HandleMark hm;
3268 VerifyRegionClosure blk(true, _vo);
3269 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3270 _g1h->workers()->active_workers(),
3271 HeapRegion::ParVerifyClaimValue);
3272 if (blk.failures()) {
3273 _failures = true;
3274 }
3275 }
3276 };
3277
3278 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3279 if (SafepointSynchronize::is_at_safepoint()) {
3280 assert(Thread::current()->is_VM_thread(),
3281 "Expected to be executed serially by the VM thread at this point");
3282
3283 if (!silent) { gclog_or_tty->print("Roots "); }
3284 VerifyRootsClosure rootsCl(vo);
3285 VerifyKlassClosure klassCl(this, &rootsCl);
3286 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3287
3288 // We apply the relevant closures to all the oops in the
3289 // system dictionary, class loader data graph, the string table
3290 // and the nmethods in the code cache.
3291 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3292 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3293
3294 process_all_roots(true, // activate StrongRootsScope
3295 SO_AllCodeCache, // roots scanning options
3296 &rootsCl,
3297 &cldCl,
3298 &blobsCl);
3299
3300 bool failures = rootsCl.failures() || codeRootsCl.failures();
3301
3302 if (vo != VerifyOption_G1UseMarkWord) {
3303 // If we're verifying during a full GC then the region sets
3304 // will have been torn down at the start of the GC. Therefore
3305 // verifying the region sets will fail. So we only verify
3306 // the region sets when not in a full GC.
3307 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3308 verify_region_sets();
3309 }
3310
3311 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3312 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3313 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3314 "sanity check");
3315
3316 G1ParVerifyTask task(this, vo);
3317 assert(UseDynamicNumberOfGCThreads ||
3318 workers()->active_workers() == workers()->total_workers(),
3319 "If not dynamic should be using all the workers");
3320 int n_workers = workers()->active_workers();
3321 set_par_threads(n_workers);
3322 workers()->run_task(&task);
3323 set_par_threads(0);
3324 if (task.failures()) {
3325 failures = true;
3326 }
3327
3328 // Checks that the expected amount of parallel work was done.
3329 // The implication is that n_workers is > 0.
3330 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3331 "sanity check");
3332
3333 reset_heap_region_claim_values();
3334
3335 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3336 "sanity check");
3337 } else {
3338 VerifyRegionClosure blk(false, vo);
3339 heap_region_iterate(&blk);
3340 if (blk.failures()) {
3341 failures = true;
3342 }
3343 }
3344 if (!silent) gclog_or_tty->print("RemSet ");
3345 rem_set()->verify();
3346
3347 if (G1StringDedup::is_enabled()) {
3348 if (!silent) gclog_or_tty->print("StrDedup ");
3349 G1StringDedup::verify();
3350 }
3351
3352 if (failures) {
3353 gclog_or_tty->print_cr("Heap:");
3354 // It helps to have the per-region information in the output to
3355 // help us track down what went wrong. This is why we call
3356 // print_extended_on() instead of print_on().
3357 print_extended_on(gclog_or_tty);
3358 gclog_or_tty->cr();
3359 #ifndef PRODUCT
3360 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3361 concurrent_mark()->print_reachable("at-verification-failure",
3362 vo, false /* all */);
3363 }
3364 #endif
3365 gclog_or_tty->flush();
3366 }
3367 guarantee(!failures, "there should not have been any failures");
3368 } else {
3369 if (!silent) {
3370 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3371 if (G1StringDedup::is_enabled()) {
3372 gclog_or_tty->print(", StrDedup");
3373 }
3374 gclog_or_tty->print(") ");
3375 }
3376 }
3377 }
3378
3379 void G1CollectedHeap::verify(bool silent) {
3380 verify(silent, VerifyOption_G1UsePrevMarking);
3381 }
3382
3383 double G1CollectedHeap::verify(bool guard, const char* msg) {
3384 double verify_time_ms = 0.0;
3385
3386 if (guard && total_collections() >= VerifyGCStartAt) {
3387 double verify_start = os::elapsedTime();
3388 HandleMark hm; // Discard invalid handles created during verification
3389 prepare_for_verify();
3390 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3391 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3392 }
3393
3394 return verify_time_ms;
3395 }
3396
3397 void G1CollectedHeap::verify_before_gc() {
3398 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3399 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3400 }
3401
3402 void G1CollectedHeap::verify_after_gc() {
3403 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3404 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3405 }
3406
3407 class PrintRegionClosure: public HeapRegionClosure {
3408 outputStream* _st;
3409 public:
3410 PrintRegionClosure(outputStream* st) : _st(st) {}
3411 bool doHeapRegion(HeapRegion* r) {
3412 r->print_on(_st);
3413 return false;
3414 }
3415 };
3416
3417 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3418 const HeapRegion* hr,
3419 const VerifyOption vo) const {
3420 switch (vo) {
3421 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3422 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3423 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3424 default: ShouldNotReachHere();
3425 }
3426 return false; // keep some compilers happy
3427 }
3428
3429 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3430 const VerifyOption vo) const {
3431 switch (vo) {
3432 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3433 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3434 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3435 default: ShouldNotReachHere();
3436 }
3437 return false; // keep some compilers happy
3438 }
3439
3440 void G1CollectedHeap::print_on(outputStream* st) const {
3441 st->print(" %-20s", "garbage-first heap");
3442 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3443 capacity()/K, used_unlocked()/K);
3444 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3445 _hrs.reserved().start(),
3446 _hrs.reserved().start() + _hrs.length() + HeapRegion::GrainWords,
3447 _hrs.reserved().end());
3448 st->cr();
3449 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3450 uint young_regions = _young_list->length();
3451 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3452 (size_t) young_regions * HeapRegion::GrainBytes / K);
3453 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3454 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3455 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3456 st->cr();
3457 MetaspaceAux::print_on(st);
3458 }
3459
3460 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3461 print_on(st);
3462
3463 // Print the per-region information.
3464 st->cr();
3465 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3466 "HS=humongous(starts), HC=humongous(continues), "
3467 "CS=collection set, F=free, TS=gc time stamp, "
3468 "PTAMS=previous top-at-mark-start, "
3469 "NTAMS=next top-at-mark-start)");
3470 PrintRegionClosure blk(st);
3471 heap_region_iterate(&blk);
3472 }
3473
3474 void G1CollectedHeap::print_on_error(outputStream* st) const {
3475 this->CollectedHeap::print_on_error(st);
3476
3477 if (_cm != NULL) {
3478 st->cr();
3479 _cm->print_on_error(st);
3480 }
3481 }
3482
3483 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3484 if (G1CollectedHeap::use_parallel_gc_threads()) {
3485 workers()->print_worker_threads_on(st);
3486 }
3487 _cmThread->print_on(st);
3488 st->cr();
3489 _cm->print_worker_threads_on(st);
3490 _cg1r->print_worker_threads_on(st);
3491 if (G1StringDedup::is_enabled()) {
3492 G1StringDedup::print_worker_threads_on(st);
3493 }
3494 }
3495
3496 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3497 if (G1CollectedHeap::use_parallel_gc_threads()) {
3498 workers()->threads_do(tc);
3499 }
3500 tc->do_thread(_cmThread);
3501 _cg1r->threads_do(tc);
3502 if (G1StringDedup::is_enabled()) {
3503 G1StringDedup::threads_do(tc);
3504 }
3505 }
3506
3507 void G1CollectedHeap::print_tracing_info() const {
3508 // We'll overload this to mean "trace GC pause statistics."
3509 if (TraceYoungGenTime || TraceOldGenTime) {
3510 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3511 // to that.
3512 g1_policy()->print_tracing_info();
3513 }
3514 if (G1SummarizeRSetStats) {
3515 g1_rem_set()->print_summary_info();
3516 }
3517 if (G1SummarizeConcMark) {
3518 concurrent_mark()->print_summary_info();
3519 }
3520 g1_policy()->print_yg_surv_rate_info();
3521 SpecializationStats::print();
3522 }
3523
3524 #ifndef PRODUCT
3525 // Helpful for debugging RSet issues.
3526
3527 class PrintRSetsClosure : public HeapRegionClosure {
3528 private:
3529 const char* _msg;
3530 size_t _occupied_sum;
3531
3532 public:
3533 bool doHeapRegion(HeapRegion* r) {
3534 HeapRegionRemSet* hrrs = r->rem_set();
3535 size_t occupied = hrrs->occupied();
3536 _occupied_sum += occupied;
3537
3538 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3539 HR_FORMAT_PARAMS(r));
3540 if (occupied == 0) {
3541 gclog_or_tty->print_cr(" RSet is empty");
3542 } else {
3543 hrrs->print();
3544 }
3545 gclog_or_tty->print_cr("----------");
3546 return false;
3547 }
3548
3549 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3550 gclog_or_tty->cr();
3551 gclog_or_tty->print_cr("========================================");
3552 gclog_or_tty->print_cr("%s", msg);
3553 gclog_or_tty->cr();
3554 }
3555
3556 ~PrintRSetsClosure() {
3557 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3558 gclog_or_tty->print_cr("========================================");
3559 gclog_or_tty->cr();
3560 }
3561 };
3562
3563 void G1CollectedHeap::print_cset_rsets() {
3564 PrintRSetsClosure cl("Printing CSet RSets");
3565 collection_set_iterate(&cl);
3566 }
3567
3568 void G1CollectedHeap::print_all_rsets() {
3569 PrintRSetsClosure cl("Printing All RSets");;
3570 heap_region_iterate(&cl);
3571 }
3572 #endif // PRODUCT
3573
3574 G1CollectedHeap* G1CollectedHeap::heap() {
3575 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3576 "not a garbage-first heap");
3577 return _g1h;
3578 }
3579
3580 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3581 // always_do_update_barrier = false;
3582 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3583 // Fill TLAB's and such
3584 accumulate_statistics_all_tlabs();
3585 ensure_parsability(true);
3586
3587 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3588 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3589 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3590 }
3591 }
3592
3593 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3594
3595 if (G1SummarizeRSetStats &&
3596 (G1SummarizeRSetStatsPeriod > 0) &&
3597 // we are at the end of the GC. Total collections has already been increased.
3598 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3599 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3600 }
3601
3602 // FIXME: what is this about?
3603 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3604 // is set.
3605 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3606 "derived pointer present"));
3607 // always_do_update_barrier = true;
3608
3609 resize_all_tlabs();
3610
3611 // We have just completed a GC. Update the soft reference
3612 // policy with the new heap occupancy
3613 Universe::update_heap_info_at_gc();
3614 }
3615
3616 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3617 unsigned int gc_count_before,
3618 bool* succeeded,
3619 GCCause::Cause gc_cause) {
3620 assert_heap_not_locked_and_not_at_safepoint();
3621 g1_policy()->record_stop_world_start();
3622 VM_G1IncCollectionPause op(gc_count_before,
3623 word_size,
3624 false, /* should_initiate_conc_mark */
3625 g1_policy()->max_pause_time_ms(),
3626 gc_cause);
3627 VMThread::execute(&op);
3628
3629 HeapWord* result = op.result();
3630 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3631 assert(result == NULL || ret_succeeded,
3632 "the result should be NULL if the VM did not succeed");
3633 *succeeded = ret_succeeded;
3634
3635 assert_heap_not_locked();
3636 return result;
3637 }
3638
3639 void
3640 G1CollectedHeap::doConcurrentMark() {
3641 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3642 if (!_cmThread->in_progress()) {
3643 _cmThread->set_started();
3644 CGC_lock->notify();
3645 }
3646 }
3647
3648 size_t G1CollectedHeap::pending_card_num() {
3649 size_t extra_cards = 0;
3650 JavaThread *curr = Threads::first();
3651 while (curr != NULL) {
3652 DirtyCardQueue& dcq = curr->dirty_card_queue();
3653 extra_cards += dcq.size();
3654 curr = curr->next();
3655 }
3656 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3657 size_t buffer_size = dcqs.buffer_size();
3658 size_t buffer_num = dcqs.completed_buffers_num();
3659
3660 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3661 // in bytes - not the number of 'entries'. We need to convert
3662 // into a number of cards.
3663 return (buffer_size * buffer_num + extra_cards) / oopSize;
3664 }
3665
3666 size_t G1CollectedHeap::cards_scanned() {
3667 return g1_rem_set()->cardsScanned();
3668 }
3669
3670 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3671 HeapRegion* region = region_at(index);
3672 assert(region->startsHumongous(), "Must start a humongous object");
3673 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3674 }
3675
3676 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3677 private:
3678 size_t _total_humongous;
3679 size_t _candidate_humongous;
3680 public:
3681 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3682 }
3683
3684 virtual bool doHeapRegion(HeapRegion* r) {
3685 if (!r->startsHumongous()) {
3686 return false;
3687 }
3688 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3689
3690 uint region_idx = r->hrs_index();
3691 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3692 // Is_candidate already filters out humongous regions with some remembered set.
3693 // This will not lead to humongous object that we mistakenly keep alive because
3694 // during young collection the remembered sets will only be added to.
3695 if (is_candidate) {
3696 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3697 _candidate_humongous++;
3698 }
3699 _total_humongous++;
3700
3701 return false;
3702 }
3703
3704 size_t total_humongous() const { return _total_humongous; }
3705 size_t candidate_humongous() const { return _candidate_humongous; }
3706 };
3707
3708 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3709 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3710 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3711 return;
3712 }
3713
3714 RegisterHumongousWithInCSetFastTestClosure cl;
3715 heap_region_iterate(&cl);
3716 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3717 cl.candidate_humongous());
3718 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3719
3720 if (_has_humongous_reclaim_candidates) {
3721 clear_humongous_is_live_table();
3722 }
3723 }
3724
3725 void
3726 G1CollectedHeap::setup_surviving_young_words() {
3727 assert(_surviving_young_words == NULL, "pre-condition");
3728 uint array_length = g1_policy()->young_cset_region_length();
3729 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3730 if (_surviving_young_words == NULL) {
3731 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3732 "Not enough space for young surv words summary.");
3733 }
3734 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3735 #ifdef ASSERT
3736 for (uint i = 0; i < array_length; ++i) {
3737 assert( _surviving_young_words[i] == 0, "memset above" );
3738 }
3739 #endif // !ASSERT
3740 }
3741
3742 void
3743 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3744 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3745 uint array_length = g1_policy()->young_cset_region_length();
3746 for (uint i = 0; i < array_length; ++i) {
3747 _surviving_young_words[i] += surv_young_words[i];
3748 }
3749 }
3750
3751 void
3752 G1CollectedHeap::cleanup_surviving_young_words() {
3753 guarantee( _surviving_young_words != NULL, "pre-condition" );
3754 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3755 _surviving_young_words = NULL;
3756 }
3757
3758 #ifdef ASSERT
3759 class VerifyCSetClosure: public HeapRegionClosure {
3760 public:
3761 bool doHeapRegion(HeapRegion* hr) {
3762 // Here we check that the CSet region's RSet is ready for parallel
3763 // iteration. The fields that we'll verify are only manipulated
3764 // when the region is part of a CSet and is collected. Afterwards,
3765 // we reset these fields when we clear the region's RSet (when the
3766 // region is freed) so they are ready when the region is
3767 // re-allocated. The only exception to this is if there's an
3768 // evacuation failure and instead of freeing the region we leave
3769 // it in the heap. In that case, we reset these fields during
3770 // evacuation failure handling.
3771 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3772
3773 // Here's a good place to add any other checks we'd like to
3774 // perform on CSet regions.
3775 return false;
3776 }
3777 };
3778 #endif // ASSERT
3779
3780 #if TASKQUEUE_STATS
3781 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3782 st->print_raw_cr("GC Task Stats");
3783 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3784 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3785 }
3786
3787 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3788 print_taskqueue_stats_hdr(st);
3789
3790 TaskQueueStats totals;
3791 const int n = workers() != NULL ? workers()->total_workers() : 1;
3792 for (int i = 0; i < n; ++i) {
3793 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3794 totals += task_queue(i)->stats;
3795 }
3796 st->print_raw("tot "); totals.print(st); st->cr();
3797
3798 DEBUG_ONLY(totals.verify());
3799 }
3800
3801 void G1CollectedHeap::reset_taskqueue_stats() {
3802 const int n = workers() != NULL ? workers()->total_workers() : 1;
3803 for (int i = 0; i < n; ++i) {
3804 task_queue(i)->stats.reset();
3805 }
3806 }
3807 #endif // TASKQUEUE_STATS
3808
3809 void G1CollectedHeap::log_gc_header() {
3810 if (!G1Log::fine()) {
3811 return;
3812 }
3813
3814 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3815
3816 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3817 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3818 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3819
3820 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3821 }
3822
3823 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3824 if (!G1Log::fine()) {
3825 return;
3826 }
3827
3828 if (G1Log::finer()) {
3829 if (evacuation_failed()) {
3830 gclog_or_tty->print(" (to-space exhausted)");
3831 }
3832 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3833 g1_policy()->phase_times()->note_gc_end();
3834 g1_policy()->phase_times()->print(pause_time_sec);
3835 g1_policy()->print_detailed_heap_transition();
3836 } else {
3837 if (evacuation_failed()) {
3838 gclog_or_tty->print("--");
3839 }
3840 g1_policy()->print_heap_transition();
3841 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3842 }
3843 gclog_or_tty->flush();
3844 }
3845
3846 bool
3847 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3848 assert_at_safepoint(true /* should_be_vm_thread */);
3849 guarantee(!is_gc_active(), "collection is not reentrant");
3850
3851 if (GC_locker::check_active_before_gc()) {
3852 return false;
3853 }
3854
3855 _gc_timer_stw->register_gc_start();
3856
3857 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3858
3859 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3860 ResourceMark rm;
3861
3862 print_heap_before_gc();
3863 trace_heap_before_gc(_gc_tracer_stw);
3864
3865 verify_region_sets_optional();
3866 verify_dirty_young_regions();
3867
3868 // This call will decide whether this pause is an initial-mark
3869 // pause. If it is, during_initial_mark_pause() will return true
3870 // for the duration of this pause.
3871 g1_policy()->decide_on_conc_mark_initiation();
3872
3873 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3874 assert(!g1_policy()->during_initial_mark_pause() ||
3875 g1_policy()->gcs_are_young(), "sanity");
3876
3877 // We also do not allow mixed GCs during marking.
3878 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3879
3880 // Record whether this pause is an initial mark. When the current
3881 // thread has completed its logging output and it's safe to signal
3882 // the CM thread, the flag's value in the policy has been reset.
3883 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3884
3885 // Inner scope for scope based logging, timers, and stats collection
3886 {
3887 EvacuationInfo evacuation_info;
3888
3889 if (g1_policy()->during_initial_mark_pause()) {
3890 // We are about to start a marking cycle, so we increment the
3891 // full collection counter.
3892 increment_old_marking_cycles_started();
3893 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3894 }
3895
3896 _gc_tracer_stw->report_yc_type(yc_type());
3897
3898 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3899
3900 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3901 workers()->active_workers() : 1);
3902 double pause_start_sec = os::elapsedTime();
3903 g1_policy()->phase_times()->note_gc_start(active_workers);
3904 log_gc_header();
3905
3906 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3907 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3908
3909 // If the secondary_free_list is not empty, append it to the
3910 // free_list. No need to wait for the cleanup operation to finish;
3911 // the region allocation code will check the secondary_free_list
3912 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3913 // set, skip this step so that the region allocation code has to
3914 // get entries from the secondary_free_list.
3915 if (!G1StressConcRegionFreeing) {
3916 append_secondary_free_list_if_not_empty_with_lock();
3917 }
3918
3919 assert(check_young_list_well_formed(), "young list should be well formed");
3920 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3921 "sanity check");
3922
3923 // Don't dynamically change the number of GC threads this early. A value of
3924 // 0 is used to indicate serial work. When parallel work is done,
3925 // it will be set.
3926
3927 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3928 IsGCActiveMark x;
3929
3930 gc_prologue(false);
3931 increment_total_collections(false /* full gc */);
3932 increment_gc_time_stamp();
3933
3934 verify_before_gc();
3935
3936 check_bitmaps("GC Start");
3937
3938 COMPILER2_PRESENT(DerivedPointerTable::clear());
3939
3940 // Please see comment in g1CollectedHeap.hpp and
3941 // G1CollectedHeap::ref_processing_init() to see how
3942 // reference processing currently works in G1.
3943
3944 // Enable discovery in the STW reference processor
3945 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3946 true /*verify_no_refs*/);
3947
3948 {
3949 // We want to temporarily turn off discovery by the
3950 // CM ref processor, if necessary, and turn it back on
3951 // on again later if we do. Using a scoped
3952 // NoRefDiscovery object will do this.
3953 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3954
3955 // Forget the current alloc region (we might even choose it to be part
3956 // of the collection set!).
3957 release_mutator_alloc_region();
3958
3959 // We should call this after we retire the mutator alloc
3960 // region(s) so that all the ALLOC / RETIRE events are generated
3961 // before the start GC event.
3962 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3963
3964 // This timing is only used by the ergonomics to handle our pause target.
3965 // It is unclear why this should not include the full pause. We will
3966 // investigate this in CR 7178365.
3967 //
3968 // Preserving the old comment here if that helps the investigation:
3969 //
3970 // The elapsed time induced by the start time below deliberately elides
3971 // the possible verification above.
3972 double sample_start_time_sec = os::elapsedTime();
3973
3974 #if YOUNG_LIST_VERBOSE
3975 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3976 _young_list->print();
3977 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3978 #endif // YOUNG_LIST_VERBOSE
3979
3980 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3981
3982 double scan_wait_start = os::elapsedTime();
3983 // We have to wait until the CM threads finish scanning the
3984 // root regions as it's the only way to ensure that all the
3985 // objects on them have been correctly scanned before we start
3986 // moving them during the GC.
3987 bool waited = _cm->root_regions()->wait_until_scan_finished();
3988 double wait_time_ms = 0.0;
3989 if (waited) {
3990 double scan_wait_end = os::elapsedTime();
3991 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3992 }
3993 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3994
3995 #if YOUNG_LIST_VERBOSE
3996 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3997 _young_list->print();
3998 #endif // YOUNG_LIST_VERBOSE
3999
4000 if (g1_policy()->during_initial_mark_pause()) {
4001 concurrent_mark()->checkpointRootsInitialPre();
4002 }
4003
4004 #if YOUNG_LIST_VERBOSE
4005 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4006 _young_list->print();
4007 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4008 #endif // YOUNG_LIST_VERBOSE
4009
4010 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4011
4012 register_humongous_regions_with_in_cset_fast_test();
4013
4014 _cm->note_start_of_gc();
4015 // We should not verify the per-thread SATB buffers given that
4016 // we have not filtered them yet (we'll do so during the
4017 // GC). We also call this after finalize_cset() to
4018 // ensure that the CSet has been finalized.
4019 _cm->verify_no_cset_oops(true /* verify_stacks */,
4020 true /* verify_enqueued_buffers */,
4021 false /* verify_thread_buffers */,
4022 true /* verify_fingers */);
4023
4024 if (_hr_printer.is_active()) {
4025 HeapRegion* hr = g1_policy()->collection_set();
4026 while (hr != NULL) {
4027 G1HRPrinter::RegionType type;
4028 if (!hr->is_young()) {
4029 type = G1HRPrinter::Old;
4030 } else if (hr->is_survivor()) {
4031 type = G1HRPrinter::Survivor;
4032 } else {
4033 type = G1HRPrinter::Eden;
4034 }
4035 _hr_printer.cset(hr);
4036 hr = hr->next_in_collection_set();
4037 }
4038 }
4039
4040 #ifdef ASSERT
4041 VerifyCSetClosure cl;
4042 collection_set_iterate(&cl);
4043 #endif // ASSERT
4044
4045 setup_surviving_young_words();
4046
4047 // Initialize the GC alloc regions.
4048 init_gc_alloc_regions(evacuation_info);
4049
4050 // Actually do the work...
4051 evacuate_collection_set(evacuation_info);
4052
4053 // We do this to mainly verify the per-thread SATB buffers
4054 // (which have been filtered by now) since we didn't verify
4055 // them earlier. No point in re-checking the stacks / enqueued
4056 // buffers given that the CSet has not changed since last time
4057 // we checked.
4058 _cm->verify_no_cset_oops(false /* verify_stacks */,
4059 false /* verify_enqueued_buffers */,
4060 true /* verify_thread_buffers */,
4061 true /* verify_fingers */);
4062
4063 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4064
4065 eagerly_reclaim_humongous_regions();
4066
4067 g1_policy()->clear_collection_set();
4068
4069 cleanup_surviving_young_words();
4070
4071 // Start a new incremental collection set for the next pause.
4072 g1_policy()->start_incremental_cset_building();
4073
4074 clear_cset_fast_test();
4075
4076 _young_list->reset_sampled_info();
4077
4078 // Don't check the whole heap at this point as the
4079 // GC alloc regions from this pause have been tagged
4080 // as survivors and moved on to the survivor list.
4081 // Survivor regions will fail the !is_young() check.
4082 assert(check_young_list_empty(false /* check_heap */),
4083 "young list should be empty");
4084
4085 #if YOUNG_LIST_VERBOSE
4086 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4087 _young_list->print();
4088 #endif // YOUNG_LIST_VERBOSE
4089
4090 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4091 _young_list->first_survivor_region(),
4092 _young_list->last_survivor_region());
4093
4094 _young_list->reset_auxilary_lists();
4095
4096 if (evacuation_failed()) {
4097 _summary_bytes_used = recalculate_used();
4098 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4099 for (uint i = 0; i < n_queues; i++) {
4100 if (_evacuation_failed_info_array[i].has_failed()) {
4101 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4102 }
4103 }
4104 } else {
4105 // The "used" of the the collection set have already been subtracted
4106 // when they were freed. Add in the bytes evacuated.
4107 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4108 }
4109
4110 if (g1_policy()->during_initial_mark_pause()) {
4111 // We have to do this before we notify the CM threads that
4112 // they can start working to make sure that all the
4113 // appropriate initialization is done on the CM object.
4114 concurrent_mark()->checkpointRootsInitialPost();
4115 set_marking_started();
4116 // Note that we don't actually trigger the CM thread at
4117 // this point. We do that later when we're sure that
4118 // the current thread has completed its logging output.
4119 }
4120
4121 allocate_dummy_regions();
4122
4123 #if YOUNG_LIST_VERBOSE
4124 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4125 _young_list->print();
4126 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4127 #endif // YOUNG_LIST_VERBOSE
4128
4129 init_mutator_alloc_region();
4130
4131 {
4132 size_t expand_bytes = g1_policy()->expansion_amount();
4133 if (expand_bytes > 0) {
4134 size_t bytes_before = capacity();
4135 // No need for an ergo verbose message here,
4136 // expansion_amount() does this when it returns a value > 0.
4137 if (!expand(expand_bytes)) {
4138 // We failed to expand the heap. Cannot do anything about it.
4139 }
4140 }
4141 }
4142
4143 // We redo the verification but now wrt to the new CSet which
4144 // has just got initialized after the previous CSet was freed.
4145 _cm->verify_no_cset_oops(true /* verify_stacks */,
4146 true /* verify_enqueued_buffers */,
4147 true /* verify_thread_buffers */,
4148 true /* verify_fingers */);
4149 _cm->note_end_of_gc();
4150
4151 // This timing is only used by the ergonomics to handle our pause target.
4152 // It is unclear why this should not include the full pause. We will
4153 // investigate this in CR 7178365.
4154 double sample_end_time_sec = os::elapsedTime();
4155 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4156 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4157
4158 MemoryService::track_memory_usage();
4159
4160 // In prepare_for_verify() below we'll need to scan the deferred
4161 // update buffers to bring the RSets up-to-date if
4162 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4163 // the update buffers we'll probably need to scan cards on the
4164 // regions we just allocated to (i.e., the GC alloc
4165 // regions). However, during the last GC we called
4166 // set_saved_mark() on all the GC alloc regions, so card
4167 // scanning might skip the [saved_mark_word()...top()] area of
4168 // those regions (i.e., the area we allocated objects into
4169 // during the last GC). But it shouldn't. Given that
4170 // saved_mark_word() is conditional on whether the GC time stamp
4171 // on the region is current or not, by incrementing the GC time
4172 // stamp here we invalidate all the GC time stamps on all the
4173 // regions and saved_mark_word() will simply return top() for
4174 // all the regions. This is a nicer way of ensuring this rather
4175 // than iterating over the regions and fixing them. In fact, the
4176 // GC time stamp increment here also ensures that
4177 // saved_mark_word() will return top() between pauses, i.e.,
4178 // during concurrent refinement. So we don't need the
4179 // is_gc_active() check to decided which top to use when
4180 // scanning cards (see CR 7039627).
4181 increment_gc_time_stamp();
4182
4183 verify_after_gc();
4184 check_bitmaps("GC End");
4185
4186 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4187 ref_processor_stw()->verify_no_references_recorded();
4188
4189 // CM reference discovery will be re-enabled if necessary.
4190 }
4191
4192 // We should do this after we potentially expand the heap so
4193 // that all the COMMIT events are generated before the end GC
4194 // event, and after we retire the GC alloc regions so that all
4195 // RETIRE events are generated before the end GC event.
4196 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4197
4198 #ifdef TRACESPINNING
4199 ParallelTaskTerminator::print_termination_counts();
4200 #endif
4201
4202 gc_epilogue(false);
4203 }
4204
4205 // Print the remainder of the GC log output.
4206 log_gc_footer(os::elapsedTime() - pause_start_sec);
4207
4208 // It is not yet to safe to tell the concurrent mark to
4209 // start as we have some optional output below. We don't want the
4210 // output from the concurrent mark thread interfering with this
4211 // logging output either.
4212
4213 _hrs.verify_optional();
4214 verify_region_sets_optional();
4215
4216 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4217 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4218
4219 print_heap_after_gc();
4220 trace_heap_after_gc(_gc_tracer_stw);
4221
4222 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4223 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4224 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4225 // before any GC notifications are raised.
4226 g1mm()->update_sizes();
4227
4228 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4229 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4230 _gc_timer_stw->register_gc_end();
4231 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4232 }
4233 // It should now be safe to tell the concurrent mark thread to start
4234 // without its logging output interfering with the logging output
4235 // that came from the pause.
4236
4237 if (should_start_conc_mark) {
4238 // CAUTION: after the doConcurrentMark() call below,
4239 // the concurrent marking thread(s) could be running
4240 // concurrently with us. Make sure that anything after
4241 // this point does not assume that we are the only GC thread
4242 // running. Note: of course, the actual marking work will
4243 // not start until the safepoint itself is released in
4244 // SuspendibleThreadSet::desynchronize().
4245 doConcurrentMark();
4246 }
4247
4248 return true;
4249 }
4250
4251 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4252 {
4253 size_t gclab_word_size;
4254 switch (purpose) {
4255 case GCAllocForSurvived:
4256 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4257 break;
4258 case GCAllocForTenured:
4259 gclab_word_size = _old_plab_stats.desired_plab_sz();
4260 break;
4261 default:
4262 assert(false, "unknown GCAllocPurpose");
4263 gclab_word_size = _old_plab_stats.desired_plab_sz();
4264 break;
4265 }
4266
4267 // Prevent humongous PLAB sizes for two reasons:
4268 // * PLABs are allocated using a similar paths as oops, but should
4269 // never be in a humongous region
4270 // * Allowing humongous PLABs needlessly churns the region free lists
4271 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4272 }
4273
4274 void G1CollectedHeap::init_mutator_alloc_region() {
4275 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4276 _mutator_alloc_region.init();
4277 }
4278
4279 void G1CollectedHeap::release_mutator_alloc_region() {
4280 _mutator_alloc_region.release();
4281 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4282 }
4283
4284 void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) {
4285 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4286 _retained_old_gc_alloc_region = NULL;
4287
4288 // We will discard the current GC alloc region if:
4289 // a) it's in the collection set (it can happen!),
4290 // b) it's already full (no point in using it),
4291 // c) it's empty (this means that it was emptied during
4292 // a cleanup and it should be on the free list now), or
4293 // d) it's humongous (this means that it was emptied
4294 // during a cleanup and was added to the free list, but
4295 // has been subsequently used to allocate a humongous
4296 // object that may be less than the region size).
4297 if (retained_region != NULL &&
4298 !retained_region->in_collection_set() &&
4299 !(retained_region->top() == retained_region->end()) &&
4300 !retained_region->is_empty() &&
4301 !retained_region->isHumongous()) {
4302 retained_region->record_top_and_timestamp();
4303 // The retained region was added to the old region set when it was
4304 // retired. We have to remove it now, since we don't allow regions
4305 // we allocate to in the region sets. We'll re-add it later, when
4306 // it's retired again.
4307 _old_set.remove(retained_region);
4308 bool during_im = g1_policy()->during_initial_mark_pause();
4309 retained_region->note_start_of_copying(during_im);
4310 _old_gc_alloc_region.set(retained_region);
4311 _hr_printer.reuse(retained_region);
4312 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4313 }
4314 }
4315
4316 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4317 assert_at_safepoint(true /* should_be_vm_thread */);
4318
4319 _survivor_gc_alloc_region.init();
4320 _old_gc_alloc_region.init();
4321
4322 use_retained_old_gc_alloc_region(evacuation_info);
4323 }
4324
4325 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4326 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4327 _old_gc_alloc_region.count());
4328 _survivor_gc_alloc_region.release();
4329 // If we have an old GC alloc region to release, we'll save it in
4330 // _retained_old_gc_alloc_region. If we don't
4331 // _retained_old_gc_alloc_region will become NULL. This is what we
4332 // want either way so no reason to check explicitly for either
4333 // condition.
4334 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4335
4336 if (ResizePLAB) {
4337 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4338 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4339 }
4340 }
4341
4342 void G1CollectedHeap::abandon_gc_alloc_regions() {
4343 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4344 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4345 _retained_old_gc_alloc_region = NULL;
4346 }
4347
4348 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4349 _drain_in_progress = false;
4350 set_evac_failure_closure(cl);
4351 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4352 }
4353
4354 void G1CollectedHeap::finalize_for_evac_failure() {
4355 assert(_evac_failure_scan_stack != NULL &&
4356 _evac_failure_scan_stack->length() == 0,
4357 "Postcondition");
4358 assert(!_drain_in_progress, "Postcondition");
4359 delete _evac_failure_scan_stack;
4360 _evac_failure_scan_stack = NULL;
4361 }
4362
4363 void G1CollectedHeap::remove_self_forwarding_pointers() {
4364 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4365
4366 double remove_self_forwards_start = os::elapsedTime();
4367
4368 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4369
4370 if (G1CollectedHeap::use_parallel_gc_threads()) {
4371 set_par_threads();
4372 workers()->run_task(&rsfp_task);
4373 set_par_threads(0);
4374 } else {
4375 rsfp_task.work(0);
4376 }
4377
4378 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4379
4380 // Reset the claim values in the regions in the collection set.
4381 reset_cset_heap_region_claim_values();
4382
4383 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4384
4385 // Now restore saved marks, if any.
4386 assert(_objs_with_preserved_marks.size() ==
4387 _preserved_marks_of_objs.size(), "Both or none.");
4388 while (!_objs_with_preserved_marks.is_empty()) {
4389 oop obj = _objs_with_preserved_marks.pop();
4390 markOop m = _preserved_marks_of_objs.pop();
4391 obj->set_mark(m);
4392 }
4393 _objs_with_preserved_marks.clear(true);
4394 _preserved_marks_of_objs.clear(true);
4395
4396 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4397 }
4398
4399 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4400 _evac_failure_scan_stack->push(obj);
4401 }
4402
4403 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4404 assert(_evac_failure_scan_stack != NULL, "precondition");
4405
4406 while (_evac_failure_scan_stack->length() > 0) {
4407 oop obj = _evac_failure_scan_stack->pop();
4408 _evac_failure_closure->set_region(heap_region_containing(obj));
4409 obj->oop_iterate_backwards(_evac_failure_closure);
4410 }
4411 }
4412
4413 oop
4414 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4415 oop old) {
4416 assert(obj_in_cs(old),
4417 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4418 (HeapWord*) old));
4419 markOop m = old->mark();
4420 oop forward_ptr = old->forward_to_atomic(old);
4421 if (forward_ptr == NULL) {
4422 // Forward-to-self succeeded.
4423 assert(_par_scan_state != NULL, "par scan state");
4424 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4425 uint queue_num = _par_scan_state->queue_num();
4426
4427 _evacuation_failed = true;
4428 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4429 if (_evac_failure_closure != cl) {
4430 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4431 assert(!_drain_in_progress,
4432 "Should only be true while someone holds the lock.");
4433 // Set the global evac-failure closure to the current thread's.
4434 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4435 set_evac_failure_closure(cl);
4436 // Now do the common part.
4437 handle_evacuation_failure_common(old, m);
4438 // Reset to NULL.
4439 set_evac_failure_closure(NULL);
4440 } else {
4441 // The lock is already held, and this is recursive.
4442 assert(_drain_in_progress, "This should only be the recursive case.");
4443 handle_evacuation_failure_common(old, m);
4444 }
4445 return old;
4446 } else {
4447 // Forward-to-self failed. Either someone else managed to allocate
4448 // space for this object (old != forward_ptr) or they beat us in
4449 // self-forwarding it (old == forward_ptr).
4450 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4451 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4452 "should not be in the CSet",
4453 (HeapWord*) old, (HeapWord*) forward_ptr));
4454 return forward_ptr;
4455 }
4456 }
4457
4458 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4459 preserve_mark_if_necessary(old, m);
4460
4461 HeapRegion* r = heap_region_containing(old);
4462 if (!r->evacuation_failed()) {
4463 r->set_evacuation_failed(true);
4464 _hr_printer.evac_failure(r);
4465 }
4466
4467 push_on_evac_failure_scan_stack(old);
4468
4469 if (!_drain_in_progress) {
4470 // prevent recursion in copy_to_survivor_space()
4471 _drain_in_progress = true;
4472 drain_evac_failure_scan_stack();
4473 _drain_in_progress = false;
4474 }
4475 }
4476
4477 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4478 assert(evacuation_failed(), "Oversaving!");
4479 // We want to call the "for_promotion_failure" version only in the
4480 // case of a promotion failure.
4481 if (m->must_be_preserved_for_promotion_failure(obj)) {
4482 _objs_with_preserved_marks.push(obj);
4483 _preserved_marks_of_objs.push(m);
4484 }
4485 }
4486
4487 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4488 size_t word_size) {
4489 if (purpose == GCAllocForSurvived) {
4490 HeapWord* result = survivor_attempt_allocation(word_size);
4491 if (result != NULL) {
4492 return result;
4493 } else {
4494 // Let's try to allocate in the old gen in case we can fit the
4495 // object there.
4496 return old_attempt_allocation(word_size);
4497 }
4498 } else {
4499 assert(purpose == GCAllocForTenured, "sanity");
4500 HeapWord* result = old_attempt_allocation(word_size);
4501 if (result != NULL) {
4502 return result;
4503 } else {
4504 // Let's try to allocate in the survivors in case we can fit the
4505 // object there.
4506 return survivor_attempt_allocation(word_size);
4507 }
4508 }
4509
4510 ShouldNotReachHere();
4511 // Trying to keep some compilers happy.
4512 return NULL;
4513 }
4514
4515 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4516 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4517
4518 void G1ParCopyHelper::mark_object(oop obj) {
4519 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4520
4521 // We know that the object is not moving so it's safe to read its size.
4522 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4523 }
4524
4525 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4526 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4527 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4528 assert(from_obj != to_obj, "should not be self-forwarded");
4529
4530 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4531 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4532
4533 // The object might be in the process of being copied by another
4534 // worker so we cannot trust that its to-space image is
4535 // well-formed. So we have to read its size from its from-space
4536 // image which we know should not be changing.
4537 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4538 }
4539
4540 template <class T>
4541 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4542 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4543 _scanned_klass->record_modified_oops();
4544 }
4545 }
4546
4547 template <G1Barrier barrier, G1Mark do_mark_object>
4548 template <class T>
4549 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4550 T heap_oop = oopDesc::load_heap_oop(p);
4551
4552 if (oopDesc::is_null(heap_oop)) {
4553 return;
4554 }
4555
4556 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4557
4558 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4559
4560 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4561
4562 if (state == G1CollectedHeap::InCSet) {
4563 oop forwardee;
4564 if (obj->is_forwarded()) {
4565 forwardee = obj->forwardee();
4566 } else {
4567 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4568 }
4569 assert(forwardee != NULL, "forwardee should not be NULL");
4570 oopDesc::encode_store_heap_oop(p, forwardee);
4571 if (do_mark_object != G1MarkNone && forwardee != obj) {
4572 // If the object is self-forwarded we don't need to explicitly
4573 // mark it, the evacuation failure protocol will do so.
4574 mark_forwarded_object(obj, forwardee);
4575 }
4576
4577 if (barrier == G1BarrierKlass) {
4578 do_klass_barrier(p, forwardee);
4579 }
4580 } else {
4581 if (state == G1CollectedHeap::IsHumongous) {
4582 _g1->set_humongous_is_live(obj);
4583 }
4584 // The object is not in collection set. If we're a root scanning
4585 // closure during an initial mark pause then attempt to mark the object.
4586 if (do_mark_object == G1MarkFromRoot) {
4587 mark_object(obj);
4588 }
4589 }
4590
4591 if (barrier == G1BarrierEvac) {
4592 _par_scan_state->update_rs(_from, p, _worker_id);
4593 }
4594 }
4595
4596 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4597 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4598
4599 class G1ParEvacuateFollowersClosure : public VoidClosure {
4600 protected:
4601 G1CollectedHeap* _g1h;
4602 G1ParScanThreadState* _par_scan_state;
4603 RefToScanQueueSet* _queues;
4604 ParallelTaskTerminator* _terminator;
4605
4606 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4607 RefToScanQueueSet* queues() { return _queues; }
4608 ParallelTaskTerminator* terminator() { return _terminator; }
4609
4610 public:
4611 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4612 G1ParScanThreadState* par_scan_state,
4613 RefToScanQueueSet* queues,
4614 ParallelTaskTerminator* terminator)
4615 : _g1h(g1h), _par_scan_state(par_scan_state),
4616 _queues(queues), _terminator(terminator) {}
4617
4618 void do_void();
4619
4620 private:
4621 inline bool offer_termination();
4622 };
4623
4624 bool G1ParEvacuateFollowersClosure::offer_termination() {
4625 G1ParScanThreadState* const pss = par_scan_state();
4626 pss->start_term_time();
4627 const bool res = terminator()->offer_termination();
4628 pss->end_term_time();
4629 return res;
4630 }
4631
4632 void G1ParEvacuateFollowersClosure::do_void() {
4633 G1ParScanThreadState* const pss = par_scan_state();
4634 pss->trim_queue();
4635 do {
4636 pss->steal_and_trim_queue(queues());
4637 } while (!offer_termination());
4638 }
4639
4640 class G1KlassScanClosure : public KlassClosure {
4641 G1ParCopyHelper* _closure;
4642 bool _process_only_dirty;
4643 int _count;
4644 public:
4645 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4646 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4647 void do_klass(Klass* klass) {
4648 // If the klass has not been dirtied we know that there's
4649 // no references into the young gen and we can skip it.
4650 if (!_process_only_dirty || klass->has_modified_oops()) {
4651 // Clean the klass since we're going to scavenge all the metadata.
4652 klass->clear_modified_oops();
4653
4654 // Tell the closure that this klass is the Klass to scavenge
4655 // and is the one to dirty if oops are left pointing into the young gen.
4656 _closure->set_scanned_klass(klass);
4657
4658 klass->oops_do(_closure);
4659
4660 _closure->set_scanned_klass(NULL);
4661 }
4662 _count++;
4663 }
4664 };
4665
4666 class G1ParTask : public AbstractGangTask {
4667 protected:
4668 G1CollectedHeap* _g1h;
4669 RefToScanQueueSet *_queues;
4670 ParallelTaskTerminator _terminator;
4671 uint _n_workers;
4672
4673 Mutex _stats_lock;
4674 Mutex* stats_lock() { return &_stats_lock; }
4675
4676 public:
4677 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4678 : AbstractGangTask("G1 collection"),
4679 _g1h(g1h),
4680 _queues(task_queues),
4681 _terminator(0, _queues),
4682 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4683 {}
4684
4685 RefToScanQueueSet* queues() { return _queues; }
4686
4687 RefToScanQueue *work_queue(int i) {
4688 return queues()->queue(i);
4689 }
4690
4691 ParallelTaskTerminator* terminator() { return &_terminator; }
4692
4693 virtual void set_for_termination(int active_workers) {
4694 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4695 // in the young space (_par_seq_tasks) in the G1 heap
4696 // for SequentialSubTasksDone.
4697 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4698 // both of which need setting by set_n_termination().
4699 _g1h->SharedHeap::set_n_termination(active_workers);
4700 _g1h->set_n_termination(active_workers);
4701 terminator()->reset_for_reuse(active_workers);
4702 _n_workers = active_workers;
4703 }
4704
4705 // Helps out with CLD processing.
4706 //
4707 // During InitialMark we need to:
4708 // 1) Scavenge all CLDs for the young GC.
4709 // 2) Mark all objects directly reachable from strong CLDs.
4710 template <G1Mark do_mark_object>
4711 class G1CLDClosure : public CLDClosure {
4712 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4713 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4714 G1KlassScanClosure _klass_in_cld_closure;
4715 bool _claim;
4716
4717 public:
4718 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4719 bool only_young, bool claim)
4720 : _oop_closure(oop_closure),
4721 _oop_in_klass_closure(oop_closure->g1(),
4722 oop_closure->pss(),
4723 oop_closure->rp()),
4724 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4725 _claim(claim) {
4726
4727 }
4728
4729 void do_cld(ClassLoaderData* cld) {
4730 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4731 }
4732 };
4733
4734 class G1CodeBlobClosure: public CodeBlobClosure {
4735 OopClosure* _f;
4736
4737 public:
4738 G1CodeBlobClosure(OopClosure* f) : _f(f) {}
4739 void do_code_blob(CodeBlob* blob) {
4740 nmethod* that = blob->as_nmethod_or_null();
4741 if (that != NULL) {
4742 if (!that->test_set_oops_do_mark()) {
4743 that->oops_do(_f);
4744 that->fix_oop_relocations();
4745 }
4746 }
4747 }
4748 };
4749
4750 void work(uint worker_id) {
4751 if (worker_id >= _n_workers) return; // no work needed this round
4752
4753 double start_time_ms = os::elapsedTime() * 1000.0;
4754 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4755
4756 {
4757 ResourceMark rm;
4758 HandleMark hm;
4759
4760 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4761
4762 G1ParScanThreadState pss(_g1h, worker_id, rp);
4763 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4764
4765 pss.set_evac_failure_closure(&evac_failure_cl);
4766
4767 bool only_young = _g1h->g1_policy()->gcs_are_young();
4768
4769 // Non-IM young GC.
4770 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4771 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4772 only_young, // Only process dirty klasses.
4773 false); // No need to claim CLDs.
4774 // IM young GC.
4775 // Strong roots closures.
4776 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4777 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4778 false, // Process all klasses.
4779 true); // Need to claim CLDs.
4780 // Weak roots closures.
4781 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4782 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4783 false, // Process all klasses.
4784 true); // Need to claim CLDs.
4785
4786 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4787 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4788 // IM Weak code roots are handled later.
4789
4790 OopClosure* strong_root_cl;
4791 OopClosure* weak_root_cl;
4792 CLDClosure* strong_cld_cl;
4793 CLDClosure* weak_cld_cl;
4794 CodeBlobClosure* strong_code_cl;
4795
4796 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4797 // We also need to mark copied objects.
4798 strong_root_cl = &scan_mark_root_cl;
4799 strong_cld_cl = &scan_mark_cld_cl;
4800 strong_code_cl = &scan_mark_code_cl;
4801 if (ClassUnloadingWithConcurrentMark) {
4802 weak_root_cl = &scan_mark_weak_root_cl;
4803 weak_cld_cl = &scan_mark_weak_cld_cl;
4804 } else {
4805 weak_root_cl = &scan_mark_root_cl;
4806 weak_cld_cl = &scan_mark_cld_cl;
4807 }
4808 } else {
4809 strong_root_cl = &scan_only_root_cl;
4810 weak_root_cl = &scan_only_root_cl;
4811 strong_cld_cl = &scan_only_cld_cl;
4812 weak_cld_cl = &scan_only_cld_cl;
4813 strong_code_cl = &scan_only_code_cl;
4814 }
4815
4816
4817 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4818
4819 pss.start_strong_roots();
4820 _g1h->g1_process_roots(strong_root_cl,
4821 weak_root_cl,
4822 &push_heap_rs_cl,
4823 strong_cld_cl,
4824 weak_cld_cl,
4825 strong_code_cl,
4826 worker_id);
4827
4828 pss.end_strong_roots();
4829
4830 {
4831 double start = os::elapsedTime();
4832 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4833 evac.do_void();
4834 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4835 double term_ms = pss.term_time()*1000.0;
4836 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4837 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4838 }
4839 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4840 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4841
4842 if (ParallelGCVerbose) {
4843 MutexLocker x(stats_lock());
4844 pss.print_termination_stats(worker_id);
4845 }
4846
4847 assert(pss.queue_is_empty(), "should be empty");
4848
4849 // Close the inner scope so that the ResourceMark and HandleMark
4850 // destructors are executed here and are included as part of the
4851 // "GC Worker Time".
4852 }
4853
4854 double end_time_ms = os::elapsedTime() * 1000.0;
4855 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4856 }
4857 };
4858
4859 // *** Common G1 Evacuation Stuff
4860
4861 // This method is run in a GC worker.
4862
4863 void
4864 G1CollectedHeap::
4865 g1_process_roots(OopClosure* scan_non_heap_roots,
4866 OopClosure* scan_non_heap_weak_roots,
4867 OopsInHeapRegionClosure* scan_rs,
4868 CLDClosure* scan_strong_clds,
4869 CLDClosure* scan_weak_clds,
4870 CodeBlobClosure* scan_strong_code,
4871 uint worker_i) {
4872
4873 // First scan the shared roots.
4874 double ext_roots_start = os::elapsedTime();
4875 double closure_app_time_sec = 0.0;
4876
4877 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4878 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4879
4880 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4881 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4882
4883 process_roots(false, // no scoping; this is parallel code
4884 SharedHeap::SO_None,
4885 &buf_scan_non_heap_roots,
4886 &buf_scan_non_heap_weak_roots,
4887 scan_strong_clds,
4888 // Unloading Initial Marks handle the weak CLDs separately.
4889 (trace_metadata ? NULL : scan_weak_clds),
4890 scan_strong_code);
4891
4892 // Now the CM ref_processor roots.
4893 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4894 // We need to treat the discovered reference lists of the
4895 // concurrent mark ref processor as roots and keep entries
4896 // (which are added by the marking threads) on them live
4897 // until they can be processed at the end of marking.
4898 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4899 }
4900
4901 if (trace_metadata) {
4902 // Barrier to make sure all workers passed
4903 // the strong CLD and strong nmethods phases.
4904 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4905
4906 // Now take the complement of the strong CLDs.
4907 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4908 }
4909
4910 // Finish up any enqueued closure apps (attributed as object copy time).
4911 buf_scan_non_heap_roots.done();
4912 buf_scan_non_heap_weak_roots.done();
4913
4914 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4915 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4916
4917 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4918
4919 double ext_root_time_ms =
4920 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4921
4922 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4923
4924 // During conc marking we have to filter the per-thread SATB buffers
4925 // to make sure we remove any oops into the CSet (which will show up
4926 // as implicitly live).
4927 double satb_filtering_ms = 0.0;
4928 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4929 if (mark_in_progress()) {
4930 double satb_filter_start = os::elapsedTime();
4931
4932 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4933
4934 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4935 }
4936 }
4937 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4938
4939 // Now scan the complement of the collection set.
4940 MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations);
4941
4942 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4943
4944 _process_strong_tasks->all_tasks_completed();
4945 }
4946
4947 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4948 private:
4949 BoolObjectClosure* _is_alive;
4950 int _initial_string_table_size;
4951 int _initial_symbol_table_size;
4952
4953 bool _process_strings;
4954 int _strings_processed;
4955 int _strings_removed;
4956
4957 bool _process_symbols;
4958 int _symbols_processed;
4959 int _symbols_removed;
4960
4961 bool _do_in_parallel;
4962 public:
4963 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4964 AbstractGangTask("String/Symbol Unlinking"),
4965 _is_alive(is_alive),
4966 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4967 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4968 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4969
4970 _initial_string_table_size = StringTable::the_table()->table_size();
4971 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4972 if (process_strings) {
4973 StringTable::clear_parallel_claimed_index();
4974 }
4975 if (process_symbols) {
4976 SymbolTable::clear_parallel_claimed_index();
4977 }
4978 }
4979
4980 ~G1StringSymbolTableUnlinkTask() {
4981 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4982 err_msg("claim value %d after unlink less than initial string table size %d",
4983 StringTable::parallel_claimed_index(), _initial_string_table_size));
4984 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4985 err_msg("claim value %d after unlink less than initial symbol table size %d",
4986 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4987
4988 if (G1TraceStringSymbolTableScrubbing) {
4989 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4990 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4991 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4992 strings_processed(), strings_removed(),
4993 symbols_processed(), symbols_removed());
4994 }
4995 }
4996
4997 void work(uint worker_id) {
4998 if (_do_in_parallel) {
4999 int strings_processed = 0;
5000 int strings_removed = 0;
5001 int symbols_processed = 0;
5002 int symbols_removed = 0;
5003 if (_process_strings) {
5004 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5005 Atomic::add(strings_processed, &_strings_processed);
5006 Atomic::add(strings_removed, &_strings_removed);
5007 }
5008 if (_process_symbols) {
5009 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5010 Atomic::add(symbols_processed, &_symbols_processed);
5011 Atomic::add(symbols_removed, &_symbols_removed);
5012 }
5013 } else {
5014 if (_process_strings) {
5015 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5016 }
5017 if (_process_symbols) {
5018 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5019 }
5020 }
5021 }
5022
5023 size_t strings_processed() const { return (size_t)_strings_processed; }
5024 size_t strings_removed() const { return (size_t)_strings_removed; }
5025
5026 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5027 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5028 };
5029
5030 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
5031 private:
5032 static Monitor* _lock;
5033
5034 BoolObjectClosure* const _is_alive;
5035 const bool _unloading_occurred;
5036 const uint _num_workers;
5037
5038 // Variables used to claim nmethods.
5039 nmethod* _first_nmethod;
5040 volatile nmethod* _claimed_nmethod;
5041
5042 // The list of nmethods that need to be processed by the second pass.
5043 volatile nmethod* _postponed_list;
5044 volatile uint _num_entered_barrier;
5045
5046 public:
5047 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
5048 _is_alive(is_alive),
5049 _unloading_occurred(unloading_occurred),
5050 _num_workers(num_workers),
5051 _first_nmethod(NULL),
5052 _claimed_nmethod(NULL),
5053 _postponed_list(NULL),
5054 _num_entered_barrier(0)
5055 {
5056 nmethod::increase_unloading_clock();
5057 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
5058 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
5059 }
5060
5061 ~G1CodeCacheUnloadingTask() {
5062 CodeCache::verify_clean_inline_caches();
5063
5064 CodeCache::set_needs_cache_clean(false);
5065 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
5066
5067 CodeCache::verify_icholder_relocations();
5068 }
5069
5070 private:
5071 void add_to_postponed_list(nmethod* nm) {
5072 nmethod* old;
5073 do {
5074 old = (nmethod*)_postponed_list;
5075 nm->set_unloading_next(old);
5076 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
5077 }
5078
5079 void clean_nmethod(nmethod* nm) {
5080 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
5081
5082 if (postponed) {
5083 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
5084 add_to_postponed_list(nm);
5085 }
5086
5087 // Mark that this thread has been cleaned/unloaded.
5088 // After this call, it will be safe to ask if this nmethod was unloaded or not.
5089 nm->set_unloading_clock(nmethod::global_unloading_clock());
5090 }
5091
5092 void clean_nmethod_postponed(nmethod* nm) {
5093 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
5094 }
5095
5096 static const int MaxClaimNmethods = 16;
5097
5098 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
5099 nmethod* first;
5100 nmethod* last;
5101
5102 do {
5103 *num_claimed_nmethods = 0;
5104
5105 first = last = (nmethod*)_claimed_nmethod;
5106
5107 if (first != NULL) {
5108 for (int i = 0; i < MaxClaimNmethods; i++) {
5109 last = CodeCache::alive_nmethod(CodeCache::next(last));
5110
5111 if (last == NULL) {
5112 break;
5113 }
5114
5115 claimed_nmethods[i] = last;
5116 (*num_claimed_nmethods)++;
5117 }
5118 }
5119
5120 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
5121 }
5122
5123 nmethod* claim_postponed_nmethod() {
5124 nmethod* claim;
5125 nmethod* next;
5126
5127 do {
5128 claim = (nmethod*)_postponed_list;
5129 if (claim == NULL) {
5130 return NULL;
5131 }
5132
5133 next = claim->unloading_next();
5134
5135 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
5136
5137 return claim;
5138 }
5139
5140 public:
5141 // Mark that we're done with the first pass of nmethod cleaning.
5142 void barrier_mark(uint worker_id) {
5143 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5144 _num_entered_barrier++;
5145 if (_num_entered_barrier == _num_workers) {
5146 ml.notify_all();
5147 }
5148 }
5149
5150 // See if we have to wait for the other workers to
5151 // finish their first-pass nmethod cleaning work.
5152 void barrier_wait(uint worker_id) {
5153 if (_num_entered_barrier < _num_workers) {
5154 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5155 while (_num_entered_barrier < _num_workers) {
5156 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5157 }
5158 }
5159 }
5160
5161 // Cleaning and unloading of nmethods. Some work has to be postponed
5162 // to the second pass, when we know which nmethods survive.
5163 void work_first_pass(uint worker_id) {
5164 // The first nmethods is claimed by the first worker.
5165 if (worker_id == 0 && _first_nmethod != NULL) {
5166 clean_nmethod(_first_nmethod);
5167 _first_nmethod = NULL;
5168 }
5169
5170 int num_claimed_nmethods;
5171 nmethod* claimed_nmethods[MaxClaimNmethods];
5172
5173 while (true) {
5174 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5175
5176 if (num_claimed_nmethods == 0) {
5177 break;
5178 }
5179
5180 for (int i = 0; i < num_claimed_nmethods; i++) {
5181 clean_nmethod(claimed_nmethods[i]);
5182 }
5183 }
5184 }
5185
5186 void work_second_pass(uint worker_id) {
5187 nmethod* nm;
5188 // Take care of postponed nmethods.
5189 while ((nm = claim_postponed_nmethod()) != NULL) {
5190 clean_nmethod_postponed(nm);
5191 }
5192 }
5193 };
5194
5195 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5196
5197 class G1KlassCleaningTask : public StackObj {
5198 BoolObjectClosure* _is_alive;
5199 volatile jint _clean_klass_tree_claimed;
5200 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5201
5202 public:
5203 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5204 _is_alive(is_alive),
5205 _clean_klass_tree_claimed(0),
5206 _klass_iterator() {
5207 }
5208
5209 private:
5210 bool claim_clean_klass_tree_task() {
5211 if (_clean_klass_tree_claimed) {
5212 return false;
5213 }
5214
5215 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5216 }
5217
5218 InstanceKlass* claim_next_klass() {
5219 Klass* klass;
5220 do {
5221 klass =_klass_iterator.next_klass();
5222 } while (klass != NULL && !klass->oop_is_instance());
5223
5224 return (InstanceKlass*)klass;
5225 }
5226
5227 public:
5228
5229 void clean_klass(InstanceKlass* ik) {
5230 ik->clean_implementors_list(_is_alive);
5231 ik->clean_method_data(_is_alive);
5232
5233 // G1 specific cleanup work that has
5234 // been moved here to be done in parallel.
5235 ik->clean_dependent_nmethods();
5236 }
5237
5238 void work() {
5239 ResourceMark rm;
5240
5241 // One worker will clean the subklass/sibling klass tree.
5242 if (claim_clean_klass_tree_task()) {
5243 Klass::clean_subklass_tree(_is_alive);
5244 }
5245
5246 // All workers will help cleaning the classes,
5247 InstanceKlass* klass;
5248 while ((klass = claim_next_klass()) != NULL) {
5249 clean_klass(klass);
5250 }
5251 }
5252 };
5253
5254 // To minimize the remark pause times, the tasks below are done in parallel.
5255 class G1ParallelCleaningTask : public AbstractGangTask {
5256 private:
5257 G1StringSymbolTableUnlinkTask _string_symbol_task;
5258 G1CodeCacheUnloadingTask _code_cache_task;
5259 G1KlassCleaningTask _klass_cleaning_task;
5260
5261 public:
5262 // The constructor is run in the VMThread.
5263 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5264 AbstractGangTask("Parallel Cleaning"),
5265 _string_symbol_task(is_alive, process_strings, process_symbols),
5266 _code_cache_task(num_workers, is_alive, unloading_occurred),
5267 _klass_cleaning_task(is_alive) {
5268 }
5269
5270 // The parallel work done by all worker threads.
5271 void work(uint worker_id) {
5272 // Do first pass of code cache cleaning.
5273 _code_cache_task.work_first_pass(worker_id);
5274
5275 // Let the threads mark that the first pass is done.
5276 _code_cache_task.barrier_mark(worker_id);
5277
5278 // Clean the Strings and Symbols.
5279 _string_symbol_task.work(worker_id);
5280
5281 // Wait for all workers to finish the first code cache cleaning pass.
5282 _code_cache_task.barrier_wait(worker_id);
5283
5284 // Do the second code cache cleaning work, which realize on
5285 // the liveness information gathered during the first pass.
5286 _code_cache_task.work_second_pass(worker_id);
5287
5288 // Clean all klasses that were not unloaded.
5289 _klass_cleaning_task.work();
5290 }
5291 };
5292
5293
5294 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5295 bool process_strings,
5296 bool process_symbols,
5297 bool class_unloading_occurred) {
5298 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5299 workers()->active_workers() : 1);
5300
5301 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5302 n_workers, class_unloading_occurred);
5303 if (G1CollectedHeap::use_parallel_gc_threads()) {
5304 set_par_threads(n_workers);
5305 workers()->run_task(&g1_unlink_task);
5306 set_par_threads(0);
5307 } else {
5308 g1_unlink_task.work(0);
5309 }
5310 }
5311
5312 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5313 bool process_strings, bool process_symbols) {
5314 {
5315 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5316 _g1h->workers()->active_workers() : 1);
5317 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5318 if (G1CollectedHeap::use_parallel_gc_threads()) {
5319 set_par_threads(n_workers);
5320 workers()->run_task(&g1_unlink_task);
5321 set_par_threads(0);
5322 } else {
5323 g1_unlink_task.work(0);
5324 }
5325 }
5326
5327 if (G1StringDedup::is_enabled()) {
5328 G1StringDedup::unlink(is_alive);
5329 }
5330 }
5331
5332 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5333 private:
5334 DirtyCardQueueSet* _queue;
5335 public:
5336 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5337
5338 virtual void work(uint worker_id) {
5339 double start_time = os::elapsedTime();
5340
5341 RedirtyLoggedCardTableEntryClosure cl;
5342 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5343 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5344 } else {
5345 _queue->apply_closure_to_all_completed_buffers(&cl);
5346 }
5347
5348 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5349 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5350 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5351 }
5352 };
5353
5354 void G1CollectedHeap::redirty_logged_cards() {
5355 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5356 double redirty_logged_cards_start = os::elapsedTime();
5357
5358 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5359 _g1h->workers()->active_workers() : 1);
5360
5361 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5362 dirty_card_queue_set().reset_for_par_iteration();
5363 if (use_parallel_gc_threads()) {
5364 set_par_threads(n_workers);
5365 workers()->run_task(&redirty_task);
5366 set_par_threads(0);
5367 } else {
5368 redirty_task.work(0);
5369 }
5370
5371 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5372 dcq.merge_bufferlists(&dirty_card_queue_set());
5373 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5374
5375 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5376 }
5377
5378 // Weak Reference Processing support
5379
5380 // An always "is_alive" closure that is used to preserve referents.
5381 // If the object is non-null then it's alive. Used in the preservation
5382 // of referent objects that are pointed to by reference objects
5383 // discovered by the CM ref processor.
5384 class G1AlwaysAliveClosure: public BoolObjectClosure {
5385 G1CollectedHeap* _g1;
5386 public:
5387 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5388 bool do_object_b(oop p) {
5389 if (p != NULL) {
5390 return true;
5391 }
5392 return false;
5393 }
5394 };
5395
5396 bool G1STWIsAliveClosure::do_object_b(oop p) {
5397 // An object is reachable if it is outside the collection set,
5398 // or is inside and copied.
5399 return !_g1->obj_in_cs(p) || p->is_forwarded();
5400 }
5401
5402 // Non Copying Keep Alive closure
5403 class G1KeepAliveClosure: public OopClosure {
5404 G1CollectedHeap* _g1;
5405 public:
5406 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5407 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5408 void do_oop(oop* p) {
5409 oop obj = *p;
5410
5411 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5412 if (obj == NULL || cset_state == G1CollectedHeap::InNeither) {
5413 return;
5414 }
5415 if (cset_state == G1CollectedHeap::InCSet) {
5416 assert( obj->is_forwarded(), "invariant" );
5417 *p = obj->forwardee();
5418 } else {
5419 assert(!obj->is_forwarded(), "invariant" );
5420 assert(cset_state == G1CollectedHeap::IsHumongous,
5421 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5422 _g1->set_humongous_is_live(obj);
5423 }
5424 }
5425 };
5426
5427 // Copying Keep Alive closure - can be called from both
5428 // serial and parallel code as long as different worker
5429 // threads utilize different G1ParScanThreadState instances
5430 // and different queues.
5431
5432 class G1CopyingKeepAliveClosure: public OopClosure {
5433 G1CollectedHeap* _g1h;
5434 OopClosure* _copy_non_heap_obj_cl;
5435 G1ParScanThreadState* _par_scan_state;
5436
5437 public:
5438 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5439 OopClosure* non_heap_obj_cl,
5440 G1ParScanThreadState* pss):
5441 _g1h(g1h),
5442 _copy_non_heap_obj_cl(non_heap_obj_cl),
5443 _par_scan_state(pss)
5444 {}
5445
5446 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5447 virtual void do_oop( oop* p) { do_oop_work(p); }
5448
5449 template <class T> void do_oop_work(T* p) {
5450 oop obj = oopDesc::load_decode_heap_oop(p);
5451
5452 if (_g1h->is_in_cset_or_humongous(obj)) {
5453 // If the referent object has been forwarded (either copied
5454 // to a new location or to itself in the event of an
5455 // evacuation failure) then we need to update the reference
5456 // field and, if both reference and referent are in the G1
5457 // heap, update the RSet for the referent.
5458 //
5459 // If the referent has not been forwarded then we have to keep
5460 // it alive by policy. Therefore we have copy the referent.
5461 //
5462 // If the reference field is in the G1 heap then we can push
5463 // on the PSS queue. When the queue is drained (after each
5464 // phase of reference processing) the object and it's followers
5465 // will be copied, the reference field set to point to the
5466 // new location, and the RSet updated. Otherwise we need to
5467 // use the the non-heap or metadata closures directly to copy
5468 // the referent object and update the pointer, while avoiding
5469 // updating the RSet.
5470
5471 if (_g1h->is_in_g1_reserved(p)) {
5472 _par_scan_state->push_on_queue(p);
5473 } else {
5474 assert(!Metaspace::contains((const void*)p),
5475 err_msg("Unexpectedly found a pointer from metadata: "
5476 PTR_FORMAT, p));
5477 _copy_non_heap_obj_cl->do_oop(p);
5478 }
5479 }
5480 }
5481 };
5482
5483 // Serial drain queue closure. Called as the 'complete_gc'
5484 // closure for each discovered list in some of the
5485 // reference processing phases.
5486
5487 class G1STWDrainQueueClosure: public VoidClosure {
5488 protected:
5489 G1CollectedHeap* _g1h;
5490 G1ParScanThreadState* _par_scan_state;
5491
5492 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5493
5494 public:
5495 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5496 _g1h(g1h),
5497 _par_scan_state(pss)
5498 { }
5499
5500 void do_void() {
5501 G1ParScanThreadState* const pss = par_scan_state();
5502 pss->trim_queue();
5503 }
5504 };
5505
5506 // Parallel Reference Processing closures
5507
5508 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5509 // processing during G1 evacuation pauses.
5510
5511 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5512 private:
5513 G1CollectedHeap* _g1h;
5514 RefToScanQueueSet* _queues;
5515 FlexibleWorkGang* _workers;
5516 int _active_workers;
5517
5518 public:
5519 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5520 FlexibleWorkGang* workers,
5521 RefToScanQueueSet *task_queues,
5522 int n_workers) :
5523 _g1h(g1h),
5524 _queues(task_queues),
5525 _workers(workers),
5526 _active_workers(n_workers)
5527 {
5528 assert(n_workers > 0, "shouldn't call this otherwise");
5529 }
5530
5531 // Executes the given task using concurrent marking worker threads.
5532 virtual void execute(ProcessTask& task);
5533 virtual void execute(EnqueueTask& task);
5534 };
5535
5536 // Gang task for possibly parallel reference processing
5537
5538 class G1STWRefProcTaskProxy: public AbstractGangTask {
5539 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5540 ProcessTask& _proc_task;
5541 G1CollectedHeap* _g1h;
5542 RefToScanQueueSet *_task_queues;
5543 ParallelTaskTerminator* _terminator;
5544
5545 public:
5546 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5547 G1CollectedHeap* g1h,
5548 RefToScanQueueSet *task_queues,
5549 ParallelTaskTerminator* terminator) :
5550 AbstractGangTask("Process reference objects in parallel"),
5551 _proc_task(proc_task),
5552 _g1h(g1h),
5553 _task_queues(task_queues),
5554 _terminator(terminator)
5555 {}
5556
5557 virtual void work(uint worker_id) {
5558 // The reference processing task executed by a single worker.
5559 ResourceMark rm;
5560 HandleMark hm;
5561
5562 G1STWIsAliveClosure is_alive(_g1h);
5563
5564 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5565 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5566
5567 pss.set_evac_failure_closure(&evac_failure_cl);
5568
5569 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5570
5571 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5572
5573 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5574
5575 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5576 // We also need to mark copied objects.
5577 copy_non_heap_cl = ©_mark_non_heap_cl;
5578 }
5579
5580 // Keep alive closure.
5581 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5582
5583 // Complete GC closure
5584 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5585
5586 // Call the reference processing task's work routine.
5587 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5588
5589 // Note we cannot assert that the refs array is empty here as not all
5590 // of the processing tasks (specifically phase2 - pp2_work) execute
5591 // the complete_gc closure (which ordinarily would drain the queue) so
5592 // the queue may not be empty.
5593 }
5594 };
5595
5596 // Driver routine for parallel reference processing.
5597 // Creates an instance of the ref processing gang
5598 // task and has the worker threads execute it.
5599 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5600 assert(_workers != NULL, "Need parallel worker threads.");
5601
5602 ParallelTaskTerminator terminator(_active_workers, _queues);
5603 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5604
5605 _g1h->set_par_threads(_active_workers);
5606 _workers->run_task(&proc_task_proxy);
5607 _g1h->set_par_threads(0);
5608 }
5609
5610 // Gang task for parallel reference enqueueing.
5611
5612 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5613 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5614 EnqueueTask& _enq_task;
5615
5616 public:
5617 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5618 AbstractGangTask("Enqueue reference objects in parallel"),
5619 _enq_task(enq_task)
5620 { }
5621
5622 virtual void work(uint worker_id) {
5623 _enq_task.work(worker_id);
5624 }
5625 };
5626
5627 // Driver routine for parallel reference enqueueing.
5628 // Creates an instance of the ref enqueueing gang
5629 // task and has the worker threads execute it.
5630
5631 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5632 assert(_workers != NULL, "Need parallel worker threads.");
5633
5634 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5635
5636 _g1h->set_par_threads(_active_workers);
5637 _workers->run_task(&enq_task_proxy);
5638 _g1h->set_par_threads(0);
5639 }
5640
5641 // End of weak reference support closures
5642
5643 // Abstract task used to preserve (i.e. copy) any referent objects
5644 // that are in the collection set and are pointed to by reference
5645 // objects discovered by the CM ref processor.
5646
5647 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5648 protected:
5649 G1CollectedHeap* _g1h;
5650 RefToScanQueueSet *_queues;
5651 ParallelTaskTerminator _terminator;
5652 uint _n_workers;
5653
5654 public:
5655 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5656 AbstractGangTask("ParPreserveCMReferents"),
5657 _g1h(g1h),
5658 _queues(task_queues),
5659 _terminator(workers, _queues),
5660 _n_workers(workers)
5661 { }
5662
5663 void work(uint worker_id) {
5664 ResourceMark rm;
5665 HandleMark hm;
5666
5667 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5668 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5669
5670 pss.set_evac_failure_closure(&evac_failure_cl);
5671
5672 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5673
5674 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5675
5676 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5677
5678 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5679
5680 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5681 // We also need to mark copied objects.
5682 copy_non_heap_cl = ©_mark_non_heap_cl;
5683 }
5684
5685 // Is alive closure
5686 G1AlwaysAliveClosure always_alive(_g1h);
5687
5688 // Copying keep alive closure. Applied to referent objects that need
5689 // to be copied.
5690 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5691
5692 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5693
5694 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5695 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5696
5697 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5698 // So this must be true - but assert just in case someone decides to
5699 // change the worker ids.
5700 assert(0 <= worker_id && worker_id < limit, "sanity");
5701 assert(!rp->discovery_is_atomic(), "check this code");
5702
5703 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5704 for (uint idx = worker_id; idx < limit; idx += stride) {
5705 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5706
5707 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5708 while (iter.has_next()) {
5709 // Since discovery is not atomic for the CM ref processor, we
5710 // can see some null referent objects.
5711 iter.load_ptrs(DEBUG_ONLY(true));
5712 oop ref = iter.obj();
5713
5714 // This will filter nulls.
5715 if (iter.is_referent_alive()) {
5716 iter.make_referent_alive();
5717 }
5718 iter.move_to_next();
5719 }
5720 }
5721
5722 // Drain the queue - which may cause stealing
5723 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5724 drain_queue.do_void();
5725 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5726 assert(pss.queue_is_empty(), "should be");
5727 }
5728 };
5729
5730 // Weak Reference processing during an evacuation pause (part 1).
5731 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5732 double ref_proc_start = os::elapsedTime();
5733
5734 ReferenceProcessor* rp = _ref_processor_stw;
5735 assert(rp->discovery_enabled(), "should have been enabled");
5736
5737 // Any reference objects, in the collection set, that were 'discovered'
5738 // by the CM ref processor should have already been copied (either by
5739 // applying the external root copy closure to the discovered lists, or
5740 // by following an RSet entry).
5741 //
5742 // But some of the referents, that are in the collection set, that these
5743 // reference objects point to may not have been copied: the STW ref
5744 // processor would have seen that the reference object had already
5745 // been 'discovered' and would have skipped discovering the reference,
5746 // but would not have treated the reference object as a regular oop.
5747 // As a result the copy closure would not have been applied to the
5748 // referent object.
5749 //
5750 // We need to explicitly copy these referent objects - the references
5751 // will be processed at the end of remarking.
5752 //
5753 // We also need to do this copying before we process the reference
5754 // objects discovered by the STW ref processor in case one of these
5755 // referents points to another object which is also referenced by an
5756 // object discovered by the STW ref processor.
5757
5758 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5759 no_of_gc_workers == workers()->active_workers(),
5760 "Need to reset active GC workers");
5761
5762 set_par_threads(no_of_gc_workers);
5763 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5764 no_of_gc_workers,
5765 _task_queues);
5766
5767 if (G1CollectedHeap::use_parallel_gc_threads()) {
5768 workers()->run_task(&keep_cm_referents);
5769 } else {
5770 keep_cm_referents.work(0);
5771 }
5772
5773 set_par_threads(0);
5774
5775 // Closure to test whether a referent is alive.
5776 G1STWIsAliveClosure is_alive(this);
5777
5778 // Even when parallel reference processing is enabled, the processing
5779 // of JNI refs is serial and performed serially by the current thread
5780 // rather than by a worker. The following PSS will be used for processing
5781 // JNI refs.
5782
5783 // Use only a single queue for this PSS.
5784 G1ParScanThreadState pss(this, 0, NULL);
5785
5786 // We do not embed a reference processor in the copying/scanning
5787 // closures while we're actually processing the discovered
5788 // reference objects.
5789 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5790
5791 pss.set_evac_failure_closure(&evac_failure_cl);
5792
5793 assert(pss.queue_is_empty(), "pre-condition");
5794
5795 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5796
5797 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5798
5799 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5800
5801 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5802 // We also need to mark copied objects.
5803 copy_non_heap_cl = ©_mark_non_heap_cl;
5804 }
5805
5806 // Keep alive closure.
5807 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5808
5809 // Serial Complete GC closure
5810 G1STWDrainQueueClosure drain_queue(this, &pss);
5811
5812 // Setup the soft refs policy...
5813 rp->setup_policy(false);
5814
5815 ReferenceProcessorStats stats;
5816 if (!rp->processing_is_mt()) {
5817 // Serial reference processing...
5818 stats = rp->process_discovered_references(&is_alive,
5819 &keep_alive,
5820 &drain_queue,
5821 NULL,
5822 _gc_timer_stw,
5823 _gc_tracer_stw->gc_id());
5824 } else {
5825 // Parallel reference processing
5826 assert(rp->num_q() == no_of_gc_workers, "sanity");
5827 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5828
5829 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5830 stats = rp->process_discovered_references(&is_alive,
5831 &keep_alive,
5832 &drain_queue,
5833 &par_task_executor,
5834 _gc_timer_stw,
5835 _gc_tracer_stw->gc_id());
5836 }
5837
5838 _gc_tracer_stw->report_gc_reference_stats(stats);
5839
5840 // We have completed copying any necessary live referent objects.
5841 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5842
5843 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5844 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5845 }
5846
5847 // Weak Reference processing during an evacuation pause (part 2).
5848 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5849 double ref_enq_start = os::elapsedTime();
5850
5851 ReferenceProcessor* rp = _ref_processor_stw;
5852 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5853
5854 // Now enqueue any remaining on the discovered lists on to
5855 // the pending list.
5856 if (!rp->processing_is_mt()) {
5857 // Serial reference processing...
5858 rp->enqueue_discovered_references();
5859 } else {
5860 // Parallel reference enqueueing
5861
5862 assert(no_of_gc_workers == workers()->active_workers(),
5863 "Need to reset active workers");
5864 assert(rp->num_q() == no_of_gc_workers, "sanity");
5865 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5866
5867 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5868 rp->enqueue_discovered_references(&par_task_executor);
5869 }
5870
5871 rp->verify_no_references_recorded();
5872 assert(!rp->discovery_enabled(), "should have been disabled");
5873
5874 // FIXME
5875 // CM's reference processing also cleans up the string and symbol tables.
5876 // Should we do that here also? We could, but it is a serial operation
5877 // and could significantly increase the pause time.
5878
5879 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5880 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5881 }
5882
5883 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5884 _expand_heap_after_alloc_failure = true;
5885 _evacuation_failed = false;
5886
5887 // Should G1EvacuationFailureALot be in effect for this GC?
5888 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5889
5890 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5891
5892 // Disable the hot card cache.
5893 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5894 hot_card_cache->reset_hot_cache_claimed_index();
5895 hot_card_cache->set_use_cache(false);
5896
5897 uint n_workers;
5898 if (G1CollectedHeap::use_parallel_gc_threads()) {
5899 n_workers =
5900 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5901 workers()->active_workers(),
5902 Threads::number_of_non_daemon_threads());
5903 assert(UseDynamicNumberOfGCThreads ||
5904 n_workers == workers()->total_workers(),
5905 "If not dynamic should be using all the workers");
5906 workers()->set_active_workers(n_workers);
5907 set_par_threads(n_workers);
5908 } else {
5909 assert(n_par_threads() == 0,
5910 "Should be the original non-parallel value");
5911 n_workers = 1;
5912 }
5913
5914 G1ParTask g1_par_task(this, _task_queues);
5915
5916 init_for_evac_failure(NULL);
5917
5918 rem_set()->prepare_for_younger_refs_iterate(true);
5919
5920 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5921 double start_par_time_sec = os::elapsedTime();
5922 double end_par_time_sec;
5923
5924 {
5925 StrongRootsScope srs(this);
5926 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5927 if (g1_policy()->during_initial_mark_pause()) {
5928 ClassLoaderDataGraph::clear_claimed_marks();
5929 }
5930
5931 if (G1CollectedHeap::use_parallel_gc_threads()) {
5932 // The individual threads will set their evac-failure closures.
5933 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5934 // These tasks use ShareHeap::_process_strong_tasks
5935 assert(UseDynamicNumberOfGCThreads ||
5936 workers()->active_workers() == workers()->total_workers(),
5937 "If not dynamic should be using all the workers");
5938 workers()->run_task(&g1_par_task);
5939 } else {
5940 g1_par_task.set_for_termination(n_workers);
5941 g1_par_task.work(0);
5942 }
5943 end_par_time_sec = os::elapsedTime();
5944
5945 // Closing the inner scope will execute the destructor
5946 // for the StrongRootsScope object. We record the current
5947 // elapsed time before closing the scope so that time
5948 // taken for the SRS destructor is NOT included in the
5949 // reported parallel time.
5950 }
5951
5952 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5953 g1_policy()->phase_times()->record_par_time(par_time_ms);
5954
5955 double code_root_fixup_time_ms =
5956 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5957 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5958
5959 set_par_threads(0);
5960
5961 // Process any discovered reference objects - we have
5962 // to do this _before_ we retire the GC alloc regions
5963 // as we may have to copy some 'reachable' referent
5964 // objects (and their reachable sub-graphs) that were
5965 // not copied during the pause.
5966 process_discovered_references(n_workers);
5967
5968 // Weak root processing.
5969 {
5970 G1STWIsAliveClosure is_alive(this);
5971 G1KeepAliveClosure keep_alive(this);
5972 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5973 if (G1StringDedup::is_enabled()) {
5974 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5975 }
5976 }
5977
5978 release_gc_alloc_regions(n_workers, evacuation_info);
5979 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5980
5981 // Reset and re-enable the hot card cache.
5982 // Note the counts for the cards in the regions in the
5983 // collection set are reset when the collection set is freed.
5984 hot_card_cache->reset_hot_cache();
5985 hot_card_cache->set_use_cache(true);
5986
5987 // Migrate the strong code roots attached to each region in
5988 // the collection set. Ideally we would like to do this
5989 // after we have finished the scanning/evacuation of the
5990 // strong code roots for a particular heap region.
5991 migrate_strong_code_roots();
5992
5993 purge_code_root_memory();
5994
5995 if (g1_policy()->during_initial_mark_pause()) {
5996 // Reset the claim values set during marking the strong code roots
5997 reset_heap_region_claim_values();
5998 }
5999
6000 finalize_for_evac_failure();
6001
6002 if (evacuation_failed()) {
6003 remove_self_forwarding_pointers();
6004
6005 // Reset the G1EvacuationFailureALot counters and flags
6006 // Note: the values are reset only when an actual
6007 // evacuation failure occurs.
6008 NOT_PRODUCT(reset_evacuation_should_fail();)
6009 }
6010
6011 // Enqueue any remaining references remaining on the STW
6012 // reference processor's discovered lists. We need to do
6013 // this after the card table is cleaned (and verified) as
6014 // the act of enqueueing entries on to the pending list
6015 // will log these updates (and dirty their associated
6016 // cards). We need these updates logged to update any
6017 // RSets.
6018 enqueue_discovered_references(n_workers);
6019
6020 if (G1DeferredRSUpdate) {
6021 redirty_logged_cards();
6022 }
6023 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
6024 }
6025
6026 void G1CollectedHeap::free_region(HeapRegion* hr,
6027 FreeRegionList* free_list,
6028 bool par,
6029 bool locked) {
6030 assert(!hr->isHumongous(), "this is only for non-humongous regions");
6031 assert(!hr->is_empty(), "the region should not be empty");
6032 assert(_hrs.is_available(hr->hrs_index()), "region should be committed");
6033 assert(free_list != NULL, "pre-condition");
6034
6035 if (G1VerifyBitmaps) {
6036 MemRegion mr(hr->bottom(), hr->end());
6037 concurrent_mark()->clearRangePrevBitmap(mr);
6038 }
6039
6040 // Clear the card counts for this region.
6041 // Note: we only need to do this if the region is not young
6042 // (since we don't refine cards in young regions).
6043 if (!hr->is_young()) {
6044 _cg1r->hot_card_cache()->reset_card_counts(hr);
6045 }
6046 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
6047 free_list->add_ordered(hr);
6048 }
6049
6050 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
6051 FreeRegionList* free_list,
6052 bool par) {
6053 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6054 assert(free_list != NULL, "pre-condition");
6055
6056 size_t hr_capacity = hr->capacity();
6057 // We need to read this before we make the region non-humongous,
6058 // otherwise the information will be gone.
6059 uint last_index = hr->last_hc_index();
6060 hr->set_notHumongous();
6061 free_region(hr, free_list, par);
6062
6063 uint i = hr->hrs_index() + 1;
6064 while (i < last_index) {
6065 HeapRegion* curr_hr = region_at(i);
6066 assert(curr_hr->continuesHumongous(), "invariant");
6067 curr_hr->set_notHumongous();
6068 free_region(curr_hr, free_list, par);
6069 i += 1;
6070 }
6071 }
6072
6073 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6074 const HeapRegionSetCount& humongous_regions_removed) {
6075 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6076 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6077 _old_set.bulk_remove(old_regions_removed);
6078 _humongous_set.bulk_remove(humongous_regions_removed);
6079 }
6080
6081 }
6082
6083 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6084 assert(list != NULL, "list can't be null");
6085 if (!list->is_empty()) {
6086 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6087 _hrs.insert_list_into_free_list(list);
6088 }
6089 }
6090
6091 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6092 assert(_summary_bytes_used >= bytes,
6093 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6094 _summary_bytes_used, bytes));
6095 _summary_bytes_used -= bytes;
6096 }
6097
6098 class G1ParCleanupCTTask : public AbstractGangTask {
6099 G1SATBCardTableModRefBS* _ct_bs;
6100 G1CollectedHeap* _g1h;
6101 HeapRegion* volatile _su_head;
6102 public:
6103 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6104 G1CollectedHeap* g1h) :
6105 AbstractGangTask("G1 Par Cleanup CT Task"),
6106 _ct_bs(ct_bs), _g1h(g1h) { }
6107
6108 void work(uint worker_id) {
6109 HeapRegion* r;
6110 while (r = _g1h->pop_dirty_cards_region()) {
6111 clear_cards(r);
6112 }
6113 }
6114
6115 void clear_cards(HeapRegion* r) {
6116 // Cards of the survivors should have already been dirtied.
6117 if (!r->is_survivor()) {
6118 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6119 }
6120 }
6121 };
6122
6123 #ifndef PRODUCT
6124 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6125 G1CollectedHeap* _g1h;
6126 G1SATBCardTableModRefBS* _ct_bs;
6127 public:
6128 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6129 : _g1h(g1h), _ct_bs(ct_bs) { }
6130 virtual bool doHeapRegion(HeapRegion* r) {
6131 if (r->is_survivor()) {
6132 _g1h->verify_dirty_region(r);
6133 } else {
6134 _g1h->verify_not_dirty_region(r);
6135 }
6136 return false;
6137 }
6138 };
6139
6140 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6141 // All of the region should be clean.
6142 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6143 MemRegion mr(hr->bottom(), hr->end());
6144 ct_bs->verify_not_dirty_region(mr);
6145 }
6146
6147 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6148 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6149 // dirty allocated blocks as they allocate them. The thread that
6150 // retires each region and replaces it with a new one will do a
6151 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6152 // not dirty that area (one less thing to have to do while holding
6153 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6154 // is dirty.
6155 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6156 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6157 if (hr->is_young()) {
6158 ct_bs->verify_g1_young_region(mr);
6159 } else {
6160 ct_bs->verify_dirty_region(mr);
6161 }
6162 }
6163
6164 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6165 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6166 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6167 verify_dirty_region(hr);
6168 }
6169 }
6170
6171 void G1CollectedHeap::verify_dirty_young_regions() {
6172 verify_dirty_young_list(_young_list->first_region());
6173 }
6174
6175 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6176 HeapWord* tams, HeapWord* end) {
6177 guarantee(tams <= end,
6178 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6179 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6180 if (result < end) {
6181 gclog_or_tty->cr();
6182 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6183 bitmap_name, result);
6184 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6185 bitmap_name, tams, end);
6186 return false;
6187 }
6188 return true;
6189 }
6190
6191 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6192 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6193 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6194
6195 HeapWord* bottom = hr->bottom();
6196 HeapWord* ptams = hr->prev_top_at_mark_start();
6197 HeapWord* ntams = hr->next_top_at_mark_start();
6198 HeapWord* end = hr->end();
6199
6200 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6201
6202 bool res_n = true;
6203 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6204 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6205 // if we happen to be in that state.
6206 if (mark_in_progress() || !_cmThread->in_progress()) {
6207 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6208 }
6209 if (!res_p || !res_n) {
6210 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6211 HR_FORMAT_PARAMS(hr));
6212 gclog_or_tty->print_cr("#### Caller: %s", caller);
6213 return false;
6214 }
6215 return true;
6216 }
6217
6218 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6219 if (!G1VerifyBitmaps) return;
6220
6221 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6222 }
6223
6224 class G1VerifyBitmapClosure : public HeapRegionClosure {
6225 private:
6226 const char* _caller;
6227 G1CollectedHeap* _g1h;
6228 bool _failures;
6229
6230 public:
6231 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6232 _caller(caller), _g1h(g1h), _failures(false) { }
6233
6234 bool failures() { return _failures; }
6235
6236 virtual bool doHeapRegion(HeapRegion* hr) {
6237 if (hr->continuesHumongous()) return false;
6238
6239 bool result = _g1h->verify_bitmaps(_caller, hr);
6240 if (!result) {
6241 _failures = true;
6242 }
6243 return false;
6244 }
6245 };
6246
6247 void G1CollectedHeap::check_bitmaps(const char* caller) {
6248 if (!G1VerifyBitmaps) return;
6249
6250 G1VerifyBitmapClosure cl(caller, this);
6251 heap_region_iterate(&cl);
6252 guarantee(!cl.failures(), "bitmap verification");
6253 }
6254 #endif // PRODUCT
6255
6256 void G1CollectedHeap::cleanUpCardTable() {
6257 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6258 double start = os::elapsedTime();
6259
6260 {
6261 // Iterate over the dirty cards region list.
6262 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6263
6264 if (G1CollectedHeap::use_parallel_gc_threads()) {
6265 set_par_threads();
6266 workers()->run_task(&cleanup_task);
6267 set_par_threads(0);
6268 } else {
6269 while (_dirty_cards_region_list) {
6270 HeapRegion* r = _dirty_cards_region_list;
6271 cleanup_task.clear_cards(r);
6272 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6273 if (_dirty_cards_region_list == r) {
6274 // The last region.
6275 _dirty_cards_region_list = NULL;
6276 }
6277 r->set_next_dirty_cards_region(NULL);
6278 }
6279 }
6280 #ifndef PRODUCT
6281 if (G1VerifyCTCleanup || VerifyAfterGC) {
6282 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6283 heap_region_iterate(&cleanup_verifier);
6284 }
6285 #endif
6286 }
6287
6288 double elapsed = os::elapsedTime() - start;
6289 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6290 }
6291
6292 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6293 size_t pre_used = 0;
6294 FreeRegionList local_free_list("Local List for CSet Freeing");
6295
6296 double young_time_ms = 0.0;
6297 double non_young_time_ms = 0.0;
6298
6299 // Since the collection set is a superset of the the young list,
6300 // all we need to do to clear the young list is clear its
6301 // head and length, and unlink any young regions in the code below
6302 _young_list->clear();
6303
6304 G1CollectorPolicy* policy = g1_policy();
6305
6306 double start_sec = os::elapsedTime();
6307 bool non_young = true;
6308
6309 HeapRegion* cur = cs_head;
6310 int age_bound = -1;
6311 size_t rs_lengths = 0;
6312
6313 while (cur != NULL) {
6314 assert(!is_on_master_free_list(cur), "sanity");
6315 if (non_young) {
6316 if (cur->is_young()) {
6317 double end_sec = os::elapsedTime();
6318 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6319 non_young_time_ms += elapsed_ms;
6320
6321 start_sec = os::elapsedTime();
6322 non_young = false;
6323 }
6324 } else {
6325 if (!cur->is_young()) {
6326 double end_sec = os::elapsedTime();
6327 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6328 young_time_ms += elapsed_ms;
6329
6330 start_sec = os::elapsedTime();
6331 non_young = true;
6332 }
6333 }
6334
6335 rs_lengths += cur->rem_set()->occupied_locked();
6336
6337 HeapRegion* next = cur->next_in_collection_set();
6338 assert(cur->in_collection_set(), "bad CS");
6339 cur->set_next_in_collection_set(NULL);
6340 cur->set_in_collection_set(false);
6341
6342 if (cur->is_young()) {
6343 int index = cur->young_index_in_cset();
6344 assert(index != -1, "invariant");
6345 assert((uint) index < policy->young_cset_region_length(), "invariant");
6346 size_t words_survived = _surviving_young_words[index];
6347 cur->record_surv_words_in_group(words_survived);
6348
6349 // At this point the we have 'popped' cur from the collection set
6350 // (linked via next_in_collection_set()) but it is still in the
6351 // young list (linked via next_young_region()). Clear the
6352 // _next_young_region field.
6353 cur->set_next_young_region(NULL);
6354 } else {
6355 int index = cur->young_index_in_cset();
6356 assert(index == -1, "invariant");
6357 }
6358
6359 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6360 (!cur->is_young() && cur->young_index_in_cset() == -1),
6361 "invariant" );
6362
6363 if (!cur->evacuation_failed()) {
6364 MemRegion used_mr = cur->used_region();
6365
6366 // And the region is empty.
6367 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6368 pre_used += cur->used();
6369 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6370 } else {
6371 cur->uninstall_surv_rate_group();
6372 if (cur->is_young()) {
6373 cur->set_young_index_in_cset(-1);
6374 }
6375 cur->set_not_young();
6376 cur->set_evacuation_failed(false);
6377 // The region is now considered to be old.
6378 _old_set.add(cur);
6379 evacuation_info.increment_collectionset_used_after(cur->used());
6380 }
6381 cur = next;
6382 }
6383
6384 evacuation_info.set_regions_freed(local_free_list.length());
6385 policy->record_max_rs_lengths(rs_lengths);
6386 policy->cset_regions_freed();
6387
6388 double end_sec = os::elapsedTime();
6389 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6390
6391 if (non_young) {
6392 non_young_time_ms += elapsed_ms;
6393 } else {
6394 young_time_ms += elapsed_ms;
6395 }
6396
6397 prepend_to_freelist(&local_free_list);
6398 decrement_summary_bytes(pre_used);
6399 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6400 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6401 }
6402
6403 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6404 private:
6405 FreeRegionList* _free_region_list;
6406 HeapRegionSet* _proxy_set;
6407 HeapRegionSetCount _humongous_regions_removed;
6408 size_t _freed_bytes;
6409 public:
6410
6411 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6412 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6413 }
6414
6415 virtual bool doHeapRegion(HeapRegion* r) {
6416 if (!r->startsHumongous()) {
6417 return false;
6418 }
6419
6420 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6421
6422 oop obj = (oop)r->bottom();
6423 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6424
6425 // The following checks whether the humongous object is live are sufficient.
6426 // The main additional check (in addition to having a reference from the roots
6427 // or the young gen) is whether the humongous object has a remembered set entry.
6428 //
6429 // A humongous object cannot be live if there is no remembered set for it
6430 // because:
6431 // - there can be no references from within humongous starts regions referencing
6432 // the object because we never allocate other objects into them.
6433 // (I.e. there are no intra-region references that may be missed by the
6434 // remembered set)
6435 // - as soon there is a remembered set entry to the humongous starts region
6436 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6437 // until the end of a concurrent mark.
6438 //
6439 // It is not required to check whether the object has been found dead by marking
6440 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6441 // all objects allocated during that time are considered live.
6442 // SATB marking is even more conservative than the remembered set.
6443 // So if at this point in the collection there is no remembered set entry,
6444 // nobody has a reference to it.
6445 // At the start of collection we flush all refinement logs, and remembered sets
6446 // are completely up-to-date wrt to references to the humongous object.
6447 //
6448 // Other implementation considerations:
6449 // - never consider object arrays: while they are a valid target, they have not
6450 // been observed to be used as temporary objects.
6451 // - they would also pose considerable effort for cleaning up the the remembered
6452 // sets.
6453 // While this cleanup is not strictly necessary to be done (or done instantly),
6454 // given that their occurrence is very low, this saves us this additional
6455 // complexity.
6456 uint region_idx = r->hrs_index();
6457 if (g1h->humongous_is_live(region_idx) ||
6458 g1h->humongous_region_is_always_live(region_idx)) {
6459
6460 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6461 gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6462 r->isHumongous(),
6463 region_idx,
6464 r->rem_set()->occupied(),
6465 r->rem_set()->strong_code_roots_list_length(),
6466 next_bitmap->isMarked(r->bottom()),
6467 g1h->humongous_is_live(region_idx),
6468 obj->is_objArray()
6469 );
6470 }
6471
6472 return false;
6473 }
6474
6475 guarantee(!obj->is_objArray(),
6476 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6477 r->bottom()));
6478
6479 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6480 gclog_or_tty->print_cr("Reclaim humongous region %d start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6481 r->isHumongous(),
6482 r->bottom(),
6483 region_idx,
6484 r->region_num(),
6485 r->rem_set()->occupied(),
6486 r->rem_set()->strong_code_roots_list_length(),
6487 next_bitmap->isMarked(r->bottom()),
6488 g1h->humongous_is_live(region_idx),
6489 obj->is_objArray()
6490 );
6491 }
6492 // Need to clear mark bit of the humongous object if already set.
6493 if (next_bitmap->isMarked(r->bottom())) {
6494 next_bitmap->clear(r->bottom());
6495 }
6496 _freed_bytes += r->used();
6497 r->set_containing_set(NULL);
6498 _humongous_regions_removed.increment(1u, r->capacity());
6499 g1h->free_humongous_region(r, _free_region_list, false);
6500
6501 return false;
6502 }
6503
6504 HeapRegionSetCount& humongous_free_count() {
6505 return _humongous_regions_removed;
6506 }
6507
6508 size_t bytes_freed() const {
6509 return _freed_bytes;
6510 }
6511
6512 size_t humongous_reclaimed() const {
6513 return _humongous_regions_removed.length();
6514 }
6515 };
6516
6517 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6518 assert_at_safepoint(true);
6519
6520 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) {
6521 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6522 return;
6523 }
6524
6525 double start_time = os::elapsedTime();
6526
6527 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6528
6529 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6530 heap_region_iterate(&cl);
6531
6532 HeapRegionSetCount empty_set;
6533 remove_from_old_sets(empty_set, cl.humongous_free_count());
6534
6535 G1HRPrinter* hr_printer = _g1h->hr_printer();
6536 if (hr_printer->is_active()) {
6537 FreeRegionListIterator iter(&local_cleanup_list);
6538 while (iter.more_available()) {
6539 HeapRegion* hr = iter.get_next();
6540 hr_printer->cleanup(hr);
6541 }
6542 }
6543
6544 prepend_to_freelist(&local_cleanup_list);
6545 decrement_summary_bytes(cl.bytes_freed());
6546
6547 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6548 cl.humongous_reclaimed());
6549 }
6550
6551 // This routine is similar to the above but does not record
6552 // any policy statistics or update free lists; we are abandoning
6553 // the current incremental collection set in preparation of a
6554 // full collection. After the full GC we will start to build up
6555 // the incremental collection set again.
6556 // This is only called when we're doing a full collection
6557 // and is immediately followed by the tearing down of the young list.
6558
6559 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6560 HeapRegion* cur = cs_head;
6561
6562 while (cur != NULL) {
6563 HeapRegion* next = cur->next_in_collection_set();
6564 assert(cur->in_collection_set(), "bad CS");
6565 cur->set_next_in_collection_set(NULL);
6566 cur->set_in_collection_set(false);
6567 cur->set_young_index_in_cset(-1);
6568 cur = next;
6569 }
6570 }
6571
6572 void G1CollectedHeap::set_free_regions_coming() {
6573 if (G1ConcRegionFreeingVerbose) {
6574 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6575 "setting free regions coming");
6576 }
6577
6578 assert(!free_regions_coming(), "pre-condition");
6579 _free_regions_coming = true;
6580 }
6581
6582 void G1CollectedHeap::reset_free_regions_coming() {
6583 assert(free_regions_coming(), "pre-condition");
6584
6585 {
6586 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6587 _free_regions_coming = false;
6588 SecondaryFreeList_lock->notify_all();
6589 }
6590
6591 if (G1ConcRegionFreeingVerbose) {
6592 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6593 "reset free regions coming");
6594 }
6595 }
6596
6597 void G1CollectedHeap::wait_while_free_regions_coming() {
6598 // Most of the time we won't have to wait, so let's do a quick test
6599 // first before we take the lock.
6600 if (!free_regions_coming()) {
6601 return;
6602 }
6603
6604 if (G1ConcRegionFreeingVerbose) {
6605 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6606 "waiting for free regions");
6607 }
6608
6609 {
6610 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6611 while (free_regions_coming()) {
6612 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6613 }
6614 }
6615
6616 if (G1ConcRegionFreeingVerbose) {
6617 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6618 "done waiting for free regions");
6619 }
6620 }
6621
6622 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6623 assert(heap_lock_held_for_gc(),
6624 "the heap lock should already be held by or for this thread");
6625 _young_list->push_region(hr);
6626 }
6627
6628 class NoYoungRegionsClosure: public HeapRegionClosure {
6629 private:
6630 bool _success;
6631 public:
6632 NoYoungRegionsClosure() : _success(true) { }
6633 bool doHeapRegion(HeapRegion* r) {
6634 if (r->is_young()) {
6635 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6636 r->bottom(), r->end());
6637 _success = false;
6638 }
6639 return false;
6640 }
6641 bool success() { return _success; }
6642 };
6643
6644 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6645 bool ret = _young_list->check_list_empty(check_sample);
6646
6647 if (check_heap) {
6648 NoYoungRegionsClosure closure;
6649 heap_region_iterate(&closure);
6650 ret = ret && closure.success();
6651 }
6652
6653 return ret;
6654 }
6655
6656 class TearDownRegionSetsClosure : public HeapRegionClosure {
6657 private:
6658 HeapRegionSet *_old_set;
6659
6660 public:
6661 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6662
6663 bool doHeapRegion(HeapRegion* r) {
6664 if (r->is_empty()) {
6665 // We ignore empty regions, we'll empty the free list afterwards
6666 } else if (r->is_young()) {
6667 // We ignore young regions, we'll empty the young list afterwards
6668 } else if (r->isHumongous()) {
6669 // We ignore humongous regions, we're not tearing down the
6670 // humongous region set
6671 } else {
6672 // The rest should be old
6673 _old_set->remove(r);
6674 }
6675 return false;
6676 }
6677
6678 ~TearDownRegionSetsClosure() {
6679 assert(_old_set->is_empty(), "post-condition");
6680 }
6681 };
6682
6683 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6684 assert_at_safepoint(true /* should_be_vm_thread */);
6685
6686 if (!free_list_only) {
6687 TearDownRegionSetsClosure cl(&_old_set);
6688 heap_region_iterate(&cl);
6689
6690 // Note that emptying the _young_list is postponed and instead done as
6691 // the first step when rebuilding the regions sets again. The reason for
6692 // this is that during a full GC string deduplication needs to know if
6693 // a collected region was young or old when the full GC was initiated.
6694 }
6695 _hrs.remove_all_free_regions();
6696 }
6697
6698 class RebuildRegionSetsClosure : public HeapRegionClosure {
6699 private:
6700 bool _free_list_only;
6701 HeapRegionSet* _old_set;
6702 HeapRegionSeq* _hrs;
6703 size_t _total_used;
6704
6705 public:
6706 RebuildRegionSetsClosure(bool free_list_only,
6707 HeapRegionSet* old_set, HeapRegionSeq* hrs) :
6708 _free_list_only(free_list_only),
6709 _old_set(old_set), _hrs(hrs), _total_used(0) {
6710 assert(_hrs->num_free_regions() == 0, "pre-condition");
6711 if (!free_list_only) {
6712 assert(_old_set->is_empty(), "pre-condition");
6713 }
6714 }
6715
6716 bool doHeapRegion(HeapRegion* r) {
6717 if (r->continuesHumongous()) {
6718 return false;
6719 }
6720
6721 if (r->is_empty()) {
6722 // Add free regions to the free list
6723 _hrs->insert_into_free_list(r);
6724 } else if (!_free_list_only) {
6725 assert(!r->is_young(), "we should not come across young regions");
6726
6727 if (r->isHumongous()) {
6728 // We ignore humongous regions, we left the humongous set unchanged
6729 } else {
6730 // The rest should be old, add them to the old set
6731 _old_set->add(r);
6732 }
6733 _total_used += r->used();
6734 }
6735
6736 return false;
6737 }
6738
6739 size_t total_used() {
6740 return _total_used;
6741 }
6742 };
6743
6744 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6745 assert_at_safepoint(true /* should_be_vm_thread */);
6746
6747 if (!free_list_only) {
6748 _young_list->empty_list();
6749 }
6750
6751 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrs);
6752 heap_region_iterate(&cl);
6753
6754 if (!free_list_only) {
6755 _summary_bytes_used = cl.total_used();
6756 }
6757 assert(_summary_bytes_used == recalculate_used(),
6758 err_msg("inconsistent _summary_bytes_used, "
6759 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6760 _summary_bytes_used, recalculate_used()));
6761 }
6762
6763 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6764 _refine_cte_cl->set_concurrent(concurrent);
6765 }
6766
6767 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6768 HeapRegion* hr = heap_region_containing(p);
6769 return hr->is_in(p);
6770 }
6771
6772 // Methods for the mutator alloc region
6773
6774 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6775 bool force) {
6776 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6777 assert(!force || g1_policy()->can_expand_young_list(),
6778 "if force is true we should be able to expand the young list");
6779 bool young_list_full = g1_policy()->is_young_list_full();
6780 if (force || !young_list_full) {
6781 HeapRegion* new_alloc_region = new_region(word_size,
6782 false /* is_old */,
6783 false /* do_expand */);
6784 if (new_alloc_region != NULL) {
6785 set_region_short_lived_locked(new_alloc_region);
6786 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6787 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6788 return new_alloc_region;
6789 }
6790 }
6791 return NULL;
6792 }
6793
6794 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6795 size_t allocated_bytes) {
6796 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6797 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6798
6799 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6800 _summary_bytes_used += allocated_bytes;
6801 _hr_printer.retire(alloc_region);
6802 // We update the eden sizes here, when the region is retired,
6803 // instead of when it's allocated, since this is the point that its
6804 // used space has been recored in _summary_bytes_used.
6805 g1mm()->update_eden_size();
6806 }
6807
6808 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6809 bool force) {
6810 return _g1h->new_mutator_alloc_region(word_size, force);
6811 }
6812
6813 void G1CollectedHeap::set_par_threads() {
6814 // Don't change the number of workers. Use the value previously set
6815 // in the workgroup.
6816 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6817 uint n_workers = workers()->active_workers();
6818 assert(UseDynamicNumberOfGCThreads ||
6819 n_workers == workers()->total_workers(),
6820 "Otherwise should be using the total number of workers");
6821 if (n_workers == 0) {
6822 assert(false, "Should have been set in prior evacuation pause.");
6823 n_workers = ParallelGCThreads;
6824 workers()->set_active_workers(n_workers);
6825 }
6826 set_par_threads(n_workers);
6827 }
6828
6829 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6830 size_t allocated_bytes) {
6831 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6832 }
6833
6834 // Methods for the GC alloc regions
6835
6836 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6837 uint count,
6838 GCAllocPurpose ap) {
6839 assert(FreeList_lock->owned_by_self(), "pre-condition");
6840
6841 if (count < g1_policy()->max_regions(ap)) {
6842 bool survivor = (ap == GCAllocForSurvived);
6843 HeapRegion* new_alloc_region = new_region(word_size,
6844 !survivor,
6845 true /* do_expand */);
6846 if (new_alloc_region != NULL) {
6847 // We really only need to do this for old regions given that we
6848 // should never scan survivors. But it doesn't hurt to do it
6849 // for survivors too.
6850 new_alloc_region->record_top_and_timestamp();
6851 if (survivor) {
6852 new_alloc_region->set_survivor();
6853 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6854 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6855 } else {
6856 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6857 check_bitmaps("Old Region Allocation", new_alloc_region);
6858 }
6859 bool during_im = g1_policy()->during_initial_mark_pause();
6860 new_alloc_region->note_start_of_copying(during_im);
6861 return new_alloc_region;
6862 } else {
6863 g1_policy()->note_alloc_region_limit_reached(ap);
6864 }
6865 }
6866 return NULL;
6867 }
6868
6869 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6870 size_t allocated_bytes,
6871 GCAllocPurpose ap) {
6872 bool during_im = g1_policy()->during_initial_mark_pause();
6873 alloc_region->note_end_of_copying(during_im);
6874 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6875 if (ap == GCAllocForSurvived) {
6876 young_list()->add_survivor_region(alloc_region);
6877 } else {
6878 _old_set.add(alloc_region);
6879 }
6880 _hr_printer.retire(alloc_region);
6881 }
6882
6883 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6884 bool force) {
6885 assert(!force, "not supported for GC alloc regions");
6886 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6887 }
6888
6889 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6890 size_t allocated_bytes) {
6891 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6892 GCAllocForSurvived);
6893 }
6894
6895 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6896 bool force) {
6897 assert(!force, "not supported for GC alloc regions");
6898 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6899 }
6900
6901 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6902 size_t allocated_bytes) {
6903 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6904 GCAllocForTenured);
6905 }
6906
6907 HeapRegion* OldGCAllocRegion::release() {
6908 HeapRegion* cur = get();
6909 if (cur != NULL) {
6910 // Determine how far we are from the next card boundary. If it is smaller than
6911 // the minimum object size we can allocate into, expand into the next card.
6912 HeapWord* top = cur->top();
6913 HeapWord* aligned_top = (HeapWord*)align_ptr_up(top, G1BlockOffsetSharedArray::N_bytes);
6914
6915 size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);
6916
6917 if (to_allocate_words != 0) {
6918 // We are not at a card boundary. Fill up, possibly into the next, taking the
6919 // end of the region and the minimum object size into account.
6920 to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
6921 MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));
6922
6923 // Skip allocation if there is not enough space to allocate even the smallest
6924 // possible object. In this case this region will not be retained, so the
6925 // original problem cannot occur.
6926 if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
6927 HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */);
6928 CollectedHeap::fill_with_object(dummy, to_allocate_words);
6929 }
6930 }
6931 }
6932 return G1AllocRegion::release();
6933 }
6934
6935 // Heap region set verification
6936
6937 class VerifyRegionListsClosure : public HeapRegionClosure {
6938 private:
6939 HeapRegionSet* _old_set;
6940 HeapRegionSet* _humongous_set;
6941 HeapRegionSeq* _hrs;
6942
6943 public:
6944 HeapRegionSetCount _old_count;
6945 HeapRegionSetCount _humongous_count;
6946 HeapRegionSetCount _free_count;
6947
6948 VerifyRegionListsClosure(HeapRegionSet* old_set,
6949 HeapRegionSet* humongous_set,
6950 HeapRegionSeq* hrs) :
6951 _old_set(old_set), _humongous_set(humongous_set), _hrs(hrs),
6952 _old_count(), _humongous_count(), _free_count(){ }
6953
6954 bool doHeapRegion(HeapRegion* hr) {
6955 if (hr->continuesHumongous()) {
6956 return false;
6957 }
6958
6959 if (hr->is_young()) {
6960 // TODO
6961 } else if (hr->startsHumongous()) {
6962 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6963 _humongous_count.increment(1u, hr->capacity());
6964 } else if (hr->is_empty()) {
6965 assert(_hrs->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6966 _free_count.increment(1u, hr->capacity());
6967 } else {
6968 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6969 _old_count.increment(1u, hr->capacity());
6970 }
6971 return false;
6972 }
6973
6974 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionSeq* free_list) {
6975 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6976 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6977 old_set->total_capacity_bytes(), _old_count.capacity()));
6978
6979 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6980 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6981 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6982
6983 guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
6984 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6985 free_list->total_capacity_bytes(), _free_count.capacity()));
6986 }
6987 };
6988
6989 void G1CollectedHeap::verify_region_sets() {
6990 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6991
6992 // First, check the explicit lists.
6993 _hrs.verify();
6994 {
6995 // Given that a concurrent operation might be adding regions to
6996 // the secondary free list we have to take the lock before
6997 // verifying it.
6998 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6999 _secondary_free_list.verify_list();
7000 }
7001
7002 // If a concurrent region freeing operation is in progress it will
7003 // be difficult to correctly attributed any free regions we come
7004 // across to the correct free list given that they might belong to
7005 // one of several (free_list, secondary_free_list, any local lists,
7006 // etc.). So, if that's the case we will skip the rest of the
7007 // verification operation. Alternatively, waiting for the concurrent
7008 // operation to complete will have a non-trivial effect on the GC's
7009 // operation (no concurrent operation will last longer than the
7010 // interval between two calls to verification) and it might hide
7011 // any issues that we would like to catch during testing.
7012 if (free_regions_coming()) {
7013 return;
7014 }
7015
7016 // Make sure we append the secondary_free_list on the free_list so
7017 // that all free regions we will come across can be safely
7018 // attributed to the free_list.
7019 append_secondary_free_list_if_not_empty_with_lock();
7020
7021 // Finally, make sure that the region accounting in the lists is
7022 // consistent with what we see in the heap.
7023
7024 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrs);
7025 heap_region_iterate(&cl);
7026 cl.verify_counts(&_old_set, &_humongous_set, &_hrs);
7027 }
7028
7029 // Optimized nmethod scanning
7030
7031 class RegisterNMethodOopClosure: public OopClosure {
7032 G1CollectedHeap* _g1h;
7033 nmethod* _nm;
7034
7035 template <class T> void do_oop_work(T* p) {
7036 T heap_oop = oopDesc::load_heap_oop(p);
7037 if (!oopDesc::is_null(heap_oop)) {
7038 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
7039 HeapRegion* hr = _g1h->heap_region_containing(obj);
7040 assert(!hr->continuesHumongous(),
7041 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
7042 " starting at "HR_FORMAT,
7043 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
7044
7045 // HeapRegion::add_strong_code_root() avoids adding duplicate
7046 // entries but having duplicates is OK since we "mark" nmethods
7047 // as visited when we scan the strong code root lists during the GC.
7048 hr->add_strong_code_root(_nm);
7049 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
7050 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
7051 _nm, HR_FORMAT_PARAMS(hr)));
7052 }
7053 }
7054
7055 public:
7056 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
7057 _g1h(g1h), _nm(nm) {}
7058
7059 void do_oop(oop* p) { do_oop_work(p); }
7060 void do_oop(narrowOop* p) { do_oop_work(p); }
7061 };
7062
7063 class UnregisterNMethodOopClosure: public OopClosure {
7064 G1CollectedHeap* _g1h;
7065 nmethod* _nm;
7066
7067 template <class T> void do_oop_work(T* p) {
7068 T heap_oop = oopDesc::load_heap_oop(p);
7069 if (!oopDesc::is_null(heap_oop)) {
7070 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
7071 HeapRegion* hr = _g1h->heap_region_containing(obj);
7072 assert(!hr->continuesHumongous(),
7073 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
7074 " starting at "HR_FORMAT,
7075 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
7076
7077 hr->remove_strong_code_root(_nm);
7078 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
7079 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
7080 _nm, HR_FORMAT_PARAMS(hr)));
7081 }
7082 }
7083
7084 public:
7085 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
7086 _g1h(g1h), _nm(nm) {}
7087
7088 void do_oop(oop* p) { do_oop_work(p); }
7089 void do_oop(narrowOop* p) { do_oop_work(p); }
7090 };
7091
7092 void G1CollectedHeap::register_nmethod(nmethod* nm) {
7093 CollectedHeap::register_nmethod(nm);
7094
7095 guarantee(nm != NULL, "sanity");
7096 RegisterNMethodOopClosure reg_cl(this, nm);
7097 nm->oops_do(®_cl);
7098 }
7099
7100 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
7101 CollectedHeap::unregister_nmethod(nm);
7102
7103 guarantee(nm != NULL, "sanity");
7104 UnregisterNMethodOopClosure reg_cl(this, nm);
7105 nm->oops_do(®_cl, true);
7106 }
7107
7108 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
7109 public:
7110 bool doHeapRegion(HeapRegion *hr) {
7111 assert(!hr->isHumongous(),
7112 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
7113 HR_FORMAT_PARAMS(hr)));
7114 hr->migrate_strong_code_roots();
7115 return false;
7116 }
7117 };
7118
7119 void G1CollectedHeap::migrate_strong_code_roots() {
7120 MigrateCodeRootsHeapRegionClosure cl;
7121 double migrate_start = os::elapsedTime();
7122 collection_set_iterate(&cl);
7123 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
7124 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
7125 }
7126
7127 void G1CollectedHeap::purge_code_root_memory() {
7128 double purge_start = os::elapsedTime();
7129 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
7130 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
7131 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
7132 }
7133
7134 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
7135 G1CollectedHeap* _g1h;
7136
7137 public:
7138 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7139 _g1h(g1h) {}
7140
7141 void do_code_blob(CodeBlob* cb) {
7142 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7143 if (nm == NULL) {
7144 return;
7145 }
7146
7147 if (ScavengeRootsInCode) {
7148 _g1h->register_nmethod(nm);
7149 }
7150 }
7151 };
7152
7153 void G1CollectedHeap::rebuild_strong_code_roots() {
7154 RebuildStrongCodeRootClosure blob_cl(this);
7155 CodeCache::blobs_do(&blob_cl);
7156 }