1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1StringDedup.hpp"
43 #include "gc_implementation/g1/g1YCTypes.hpp"
44 #include "gc_implementation/g1/heapRegion.inline.hpp"
45 #include "gc_implementation/g1/heapRegionRemSet.hpp"
46 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
47 #include "gc_implementation/g1/vm_operations_g1.hpp"
48 #include "gc_implementation/shared/gcHeapSummary.hpp"
49 #include "gc_implementation/shared/gcTimer.hpp"
50 #include "gc_implementation/shared/gcTrace.hpp"
51 #include "gc_implementation/shared/gcTraceTime.hpp"
52 #include "gc_implementation/shared/isGCActiveMark.hpp"
53 #include "memory/gcLocker.inline.hpp"
54 #include "memory/generationSpec.hpp"
55 #include "memory/iterator.hpp"
56 #include "memory/referenceProcessor.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/oop.pcgc.inline.hpp"
59 #include "runtime/vmThread.hpp"
60 #include "utilities/ticks.hpp"
61
62 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
63
64 // turn it on so that the contents of the young list (scan-only /
65 // to-be-collected) are printed at "strategic" points before / during
66 // / after the collection --- this is useful for debugging
67 #define YOUNG_LIST_VERBOSE 0
68 // CURRENT STATUS
69 // This file is under construction. Search for "FIXME".
70
71 // INVARIANTS/NOTES
72 //
73 // All allocation activity covered by the G1CollectedHeap interface is
74 // serialized by acquiring the HeapLock. This happens in mem_allocate
75 // and allocate_new_tlab, which are the "entry" points to the
76 // allocation code from the rest of the JVM. (Note that this does not
77 // apply to TLAB allocation, which is not part of this interface: it
78 // is done by clients of this interface.)
79
80 // Notes on implementation of parallelism in different tasks.
81 //
82 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
83 // The number of GC workers is passed to heap_region_par_iterate_chunked().
84 // It does use run_task() which sets _n_workers in the task.
85 // G1ParTask executes g1_process_strong_roots() ->
86 // SharedHeap::process_strong_roots() which calls eventually to
87 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
88 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
89 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
90 //
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 SuspendibleThreadSet* _sts;
96 G1RemSet* _g1rs;
97 ConcurrentG1Refine* _cg1r;
98 bool _concurrent;
99 public:
100 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
101 G1RemSet* g1rs,
102 ConcurrentG1Refine* cg1r) :
103 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
104 {}
105 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
106 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
107 // This path is executed by the concurrent refine or mutator threads,
108 // concurrently, and so we do not care if card_ptr contains references
109 // that point into the collection set.
110 assert(!oops_into_cset, "should be");
111
112 if (_concurrent && _sts->should_yield()) {
113 // Caller will actually yield.
114 return false;
115 }
116 // Otherwise, we finished successfully; return true.
117 return true;
118 }
119 void set_concurrent(bool b) { _concurrent = b; }
120 };
121
122
123 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
124 int _calls;
125 G1CollectedHeap* _g1h;
126 CardTableModRefBS* _ctbs;
127 int _histo[256];
128 public:
129 ClearLoggedCardTableEntryClosure() :
130 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
131 {
132 for (int i = 0; i < 256; i++) _histo[i] = 0;
133 }
134 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
135 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
136 _calls++;
137 unsigned char* ujb = (unsigned char*)card_ptr;
138 int ind = (int)(*ujb);
139 _histo[ind]++;
140 *card_ptr = -1;
141 }
142 return true;
143 }
144 int calls() { return _calls; }
145 void print_histo() {
146 gclog_or_tty->print_cr("Card table value histogram:");
147 for (int i = 0; i < 256; i++) {
148 if (_histo[i] != 0) {
149 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
150 }
151 }
152 }
153 };
154
155 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
156 int _calls;
157 G1CollectedHeap* _g1h;
158 CardTableModRefBS* _ctbs;
159 public:
160 RedirtyLoggedCardTableEntryClosure() :
161 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
162
163 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
164 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
165 _calls++;
166 *card_ptr = 0;
167 }
168 return true;
169 }
170 int calls() { return _calls; }
171 };
172
173 YoungList::YoungList(G1CollectedHeap* g1h) :
174 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
175 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
176 guarantee(check_list_empty(false), "just making sure...");
177 }
178
179 void YoungList::push_region(HeapRegion *hr) {
180 assert(!hr->is_young(), "should not already be young");
181 assert(hr->get_next_young_region() == NULL, "cause it should!");
182
183 hr->set_next_young_region(_head);
184 _head = hr;
185
186 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
187 ++_length;
188 }
189
190 void YoungList::add_survivor_region(HeapRegion* hr) {
191 assert(hr->is_survivor(), "should be flagged as survivor region");
192 assert(hr->get_next_young_region() == NULL, "cause it should!");
193
194 hr->set_next_young_region(_survivor_head);
195 if (_survivor_head == NULL) {
196 _survivor_tail = hr;
197 }
198 _survivor_head = hr;
199 ++_survivor_length;
200 }
201
202 void YoungList::empty_list(HeapRegion* list) {
203 while (list != NULL) {
204 HeapRegion* next = list->get_next_young_region();
205 list->set_next_young_region(NULL);
206 list->uninstall_surv_rate_group();
207 list->set_not_young();
208 list = next;
209 }
210 }
211
212 void YoungList::empty_list() {
213 assert(check_list_well_formed(), "young list should be well formed");
214
215 empty_list(_head);
216 _head = NULL;
217 _length = 0;
218
219 empty_list(_survivor_head);
220 _survivor_head = NULL;
221 _survivor_tail = NULL;
222 _survivor_length = 0;
223
224 _last_sampled_rs_lengths = 0;
225
226 assert(check_list_empty(false), "just making sure...");
227 }
228
229 bool YoungList::check_list_well_formed() {
230 bool ret = true;
231
232 uint length = 0;
233 HeapRegion* curr = _head;
234 HeapRegion* last = NULL;
235 while (curr != NULL) {
236 if (!curr->is_young()) {
237 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
238 "incorrectly tagged (y: %d, surv: %d)",
239 curr->bottom(), curr->end(),
240 curr->is_young(), curr->is_survivor());
241 ret = false;
242 }
243 ++length;
244 last = curr;
245 curr = curr->get_next_young_region();
246 }
247 ret = ret && (length == _length);
248
249 if (!ret) {
250 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
251 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
252 length, _length);
253 }
254
255 return ret;
256 }
257
258 bool YoungList::check_list_empty(bool check_sample) {
259 bool ret = true;
260
261 if (_length != 0) {
262 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
263 _length);
264 ret = false;
265 }
266 if (check_sample && _last_sampled_rs_lengths != 0) {
267 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
268 ret = false;
269 }
270 if (_head != NULL) {
271 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
272 ret = false;
273 }
274 if (!ret) {
275 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
276 }
277
278 return ret;
279 }
280
281 void
282 YoungList::rs_length_sampling_init() {
283 _sampled_rs_lengths = 0;
284 _curr = _head;
285 }
286
287 bool
288 YoungList::rs_length_sampling_more() {
289 return _curr != NULL;
290 }
291
292 void
293 YoungList::rs_length_sampling_next() {
294 assert( _curr != NULL, "invariant" );
295 size_t rs_length = _curr->rem_set()->occupied();
296
297 _sampled_rs_lengths += rs_length;
298
299 // The current region may not yet have been added to the
300 // incremental collection set (it gets added when it is
301 // retired as the current allocation region).
302 if (_curr->in_collection_set()) {
303 // Update the collection set policy information for this region
304 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
305 }
306
307 _curr = _curr->get_next_young_region();
308 if (_curr == NULL) {
309 _last_sampled_rs_lengths = _sampled_rs_lengths;
310 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
311 }
312 }
313
314 void
315 YoungList::reset_auxilary_lists() {
316 guarantee( is_empty(), "young list should be empty" );
317 assert(check_list_well_formed(), "young list should be well formed");
318
319 // Add survivor regions to SurvRateGroup.
320 _g1h->g1_policy()->note_start_adding_survivor_regions();
321 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
322
323 int young_index_in_cset = 0;
324 for (HeapRegion* curr = _survivor_head;
325 curr != NULL;
326 curr = curr->get_next_young_region()) {
327 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
328
329 // The region is a non-empty survivor so let's add it to
330 // the incremental collection set for the next evacuation
331 // pause.
332 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
333 young_index_in_cset += 1;
334 }
335 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
336 _g1h->g1_policy()->note_stop_adding_survivor_regions();
337
338 _head = _survivor_head;
339 _length = _survivor_length;
340 if (_survivor_head != NULL) {
341 assert(_survivor_tail != NULL, "cause it shouldn't be");
342 assert(_survivor_length > 0, "invariant");
343 _survivor_tail->set_next_young_region(NULL);
344 }
345
346 // Don't clear the survivor list handles until the start of
347 // the next evacuation pause - we need it in order to re-tag
348 // the survivor regions from this evacuation pause as 'young'
349 // at the start of the next.
350
351 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
352
353 assert(check_list_well_formed(), "young list should be well formed");
354 }
355
356 void YoungList::print() {
357 HeapRegion* lists[] = {_head, _survivor_head};
358 const char* names[] = {"YOUNG", "SURVIVOR"};
359
360 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
361 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
362 HeapRegion *curr = lists[list];
363 if (curr == NULL)
364 gclog_or_tty->print_cr(" empty");
365 while (curr != NULL) {
366 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
367 HR_FORMAT_PARAMS(curr),
368 curr->prev_top_at_mark_start(),
369 curr->next_top_at_mark_start(),
370 curr->age_in_surv_rate_group_cond());
371 curr = curr->get_next_young_region();
372 }
373 }
374
375 gclog_or_tty->print_cr("");
376 }
377
378 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
379 {
380 // Claim the right to put the region on the dirty cards region list
381 // by installing a self pointer.
382 HeapRegion* next = hr->get_next_dirty_cards_region();
383 if (next == NULL) {
384 HeapRegion* res = (HeapRegion*)
385 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
386 NULL);
387 if (res == NULL) {
388 HeapRegion* head;
389 do {
390 // Put the region to the dirty cards region list.
391 head = _dirty_cards_region_list;
392 next = (HeapRegion*)
393 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
394 if (next == head) {
395 assert(hr->get_next_dirty_cards_region() == hr,
396 "hr->get_next_dirty_cards_region() != hr");
397 if (next == NULL) {
398 // The last region in the list points to itself.
399 hr->set_next_dirty_cards_region(hr);
400 } else {
401 hr->set_next_dirty_cards_region(next);
402 }
403 }
404 } while (next != head);
405 }
406 }
407 }
408
409 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
410 {
411 HeapRegion* head;
412 HeapRegion* hr;
413 do {
414 head = _dirty_cards_region_list;
415 if (head == NULL) {
416 return NULL;
417 }
418 HeapRegion* new_head = head->get_next_dirty_cards_region();
419 if (head == new_head) {
420 // The last region.
421 new_head = NULL;
422 }
423 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
424 head);
425 } while (hr != head);
426 assert(hr != NULL, "invariant");
427 hr->set_next_dirty_cards_region(NULL);
428 return hr;
429 }
430
431 void G1CollectedHeap::stop_conc_gc_threads() {
432 _cg1r->stop();
433 _cmThread->stop();
434 }
435
436 #ifdef ASSERT
437 // A region is added to the collection set as it is retired
438 // so an address p can point to a region which will be in the
439 // collection set but has not yet been retired. This method
440 // therefore is only accurate during a GC pause after all
441 // regions have been retired. It is used for debugging
442 // to check if an nmethod has references to objects that can
443 // be move during a partial collection. Though it can be
444 // inaccurate, it is sufficient for G1 because the conservative
445 // implementation of is_scavengable() for G1 will indicate that
446 // all nmethods must be scanned during a partial collection.
447 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
448 HeapRegion* hr = heap_region_containing(p);
449 return hr != NULL && hr->in_collection_set();
450 }
451 #endif
452
453 // Returns true if the reference points to an object that
454 // can move in an incremental collection.
455 bool G1CollectedHeap::is_scavengable(const void* p) {
456 G1CollectedHeap* g1h = G1CollectedHeap::heap();
457 G1CollectorPolicy* g1p = g1h->g1_policy();
458 HeapRegion* hr = heap_region_containing(p);
459 if (hr == NULL) {
460 // null
461 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
462 return false;
463 } else {
464 return !hr->isHumongous();
465 }
466 }
467
468 void G1CollectedHeap::check_ct_logs_at_safepoint() {
469 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
470 CardTableModRefBS* ct_bs = g1_barrier_set();
471
472 // Count the dirty cards at the start.
473 CountNonCleanMemRegionClosure count1(this);
474 ct_bs->mod_card_iterate(&count1);
475 int orig_count = count1.n();
476
477 // First clear the logged cards.
478 ClearLoggedCardTableEntryClosure clear;
479 dcqs.set_closure(&clear);
480 dcqs.apply_closure_to_all_completed_buffers();
481 dcqs.iterate_closure_all_threads(false);
482 clear.print_histo();
483
484 // Now ensure that there's no dirty cards.
485 CountNonCleanMemRegionClosure count2(this);
486 ct_bs->mod_card_iterate(&count2);
487 if (count2.n() != 0) {
488 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
489 count2.n(), orig_count);
490 }
491 guarantee(count2.n() == 0, "Card table should be clean.");
492
493 RedirtyLoggedCardTableEntryClosure redirty;
494 JavaThread::dirty_card_queue_set().set_closure(&redirty);
495 dcqs.apply_closure_to_all_completed_buffers();
496 dcqs.iterate_closure_all_threads(false);
497 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
498 clear.calls(), orig_count);
499 guarantee(redirty.calls() == clear.calls(),
500 "Or else mechanism is broken.");
501
502 CountNonCleanMemRegionClosure count3(this);
503 ct_bs->mod_card_iterate(&count3);
504 if (count3.n() != orig_count) {
505 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
506 orig_count, count3.n());
507 guarantee(count3.n() >= orig_count, "Should have restored them all.");
508 }
509
510 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
511 }
512
513 // Private class members.
514
515 G1CollectedHeap* G1CollectedHeap::_g1h;
516
517 // Private methods.
518
519 HeapRegion*
520 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
521 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
522 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
523 if (!_secondary_free_list.is_empty()) {
524 if (G1ConcRegionFreeingVerbose) {
525 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
526 "secondary_free_list has %u entries",
527 _secondary_free_list.length());
528 }
529 // It looks as if there are free regions available on the
530 // secondary_free_list. Let's move them to the free_list and try
531 // again to allocate from it.
532 append_secondary_free_list();
533
534 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
535 "empty we should have moved at least one entry to the free_list");
536 HeapRegion* res = _free_list.remove_region(is_old);
537 if (G1ConcRegionFreeingVerbose) {
538 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
539 "allocated "HR_FORMAT" from secondary_free_list",
540 HR_FORMAT_PARAMS(res));
541 }
542 return res;
543 }
544
545 // Wait here until we get notified either when (a) there are no
546 // more free regions coming or (b) some regions have been moved on
547 // the secondary_free_list.
548 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
549 }
550
551 if (G1ConcRegionFreeingVerbose) {
552 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
553 "could not allocate from secondary_free_list");
554 }
555 return NULL;
556 }
557
558 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
559 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
560 "the only time we use this to allocate a humongous region is "
561 "when we are allocating a single humongous region");
562
563 HeapRegion* res;
564 if (G1StressConcRegionFreeing) {
565 if (!_secondary_free_list.is_empty()) {
566 if (G1ConcRegionFreeingVerbose) {
567 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
568 "forced to look at the secondary_free_list");
569 }
570 res = new_region_try_secondary_free_list(is_old);
571 if (res != NULL) {
572 return res;
573 }
574 }
575 }
576
577 res = _free_list.remove_region(is_old);
578
579 if (res == NULL) {
580 if (G1ConcRegionFreeingVerbose) {
581 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
582 "res == NULL, trying the secondary_free_list");
583 }
584 res = new_region_try_secondary_free_list(is_old);
585 }
586 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
587 // Currently, only attempts to allocate GC alloc regions set
588 // do_expand to true. So, we should only reach here during a
589 // safepoint. If this assumption changes we might have to
590 // reconsider the use of _expand_heap_after_alloc_failure.
591 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
592
593 ergo_verbose1(ErgoHeapSizing,
594 "attempt heap expansion",
595 ergo_format_reason("region allocation request failed")
596 ergo_format_byte("allocation request"),
597 word_size * HeapWordSize);
598 if (expand(word_size * HeapWordSize)) {
599 // Given that expand() succeeded in expanding the heap, and we
600 // always expand the heap by an amount aligned to the heap
601 // region size, the free list should in theory not be empty.
602 // In either case remove_region() will check for NULL.
603 res = _free_list.remove_region(is_old);
604 } else {
605 _expand_heap_after_alloc_failure = false;
606 }
607 }
608 return res;
609 }
610
611 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
612 size_t word_size) {
613 assert(isHumongous(word_size), "word_size should be humongous");
614 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
615
616 uint first = G1_NULL_HRS_INDEX;
617 if (num_regions == 1) {
618 // Only one region to allocate, no need to go through the slower
619 // path. The caller will attempt the expansion if this fails, so
620 // let's not try to expand here too.
621 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
622 if (hr != NULL) {
623 first = hr->hrs_index();
624 } else {
625 first = G1_NULL_HRS_INDEX;
626 }
627 } else {
628 // We can't allocate humongous regions while cleanupComplete() is
629 // running, since some of the regions we find to be empty might not
630 // yet be added to the free list and it is not straightforward to
631 // know which list they are on so that we can remove them. Note
632 // that we only need to do this if we need to allocate more than
633 // one region to satisfy the current humongous allocation
634 // request. If we are only allocating one region we use the common
635 // region allocation code (see above).
636 wait_while_free_regions_coming();
637 append_secondary_free_list_if_not_empty_with_lock();
638
639 if (free_regions() >= num_regions) {
640 first = _hrs.find_contiguous(num_regions);
641 if (first != G1_NULL_HRS_INDEX) {
642 for (uint i = first; i < first + num_regions; ++i) {
643 HeapRegion* hr = region_at(i);
644 assert(hr->is_empty(), "sanity");
645 assert(is_on_master_free_list(hr), "sanity");
646 hr->set_pending_removal(true);
647 }
648 _free_list.remove_all_pending(num_regions);
649 }
650 }
651 }
652 return first;
653 }
654
655 HeapWord*
656 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
657 uint num_regions,
658 size_t word_size) {
659 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
660 assert(isHumongous(word_size), "word_size should be humongous");
661 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
662
663 // Index of last region in the series + 1.
664 uint last = first + num_regions;
665
666 // We need to initialize the region(s) we just discovered. This is
667 // a bit tricky given that it can happen concurrently with
668 // refinement threads refining cards on these regions and
669 // potentially wanting to refine the BOT as they are scanning
670 // those cards (this can happen shortly after a cleanup; see CR
671 // 6991377). So we have to set up the region(s) carefully and in
672 // a specific order.
673
674 // The word size sum of all the regions we will allocate.
675 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
676 assert(word_size <= word_size_sum, "sanity");
677
678 // This will be the "starts humongous" region.
679 HeapRegion* first_hr = region_at(first);
680 // The header of the new object will be placed at the bottom of
681 // the first region.
682 HeapWord* new_obj = first_hr->bottom();
683 // This will be the new end of the first region in the series that
684 // should also match the end of the last region in the series.
685 HeapWord* new_end = new_obj + word_size_sum;
686 // This will be the new top of the first region that will reflect
687 // this allocation.
688 HeapWord* new_top = new_obj + word_size;
689
690 // First, we need to zero the header of the space that we will be
691 // allocating. When we update top further down, some refinement
692 // threads might try to scan the region. By zeroing the header we
693 // ensure that any thread that will try to scan the region will
694 // come across the zero klass word and bail out.
695 //
696 // NOTE: It would not have been correct to have used
697 // CollectedHeap::fill_with_object() and make the space look like
698 // an int array. The thread that is doing the allocation will
699 // later update the object header to a potentially different array
700 // type and, for a very short period of time, the klass and length
701 // fields will be inconsistent. This could cause a refinement
702 // thread to calculate the object size incorrectly.
703 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
704
705 // We will set up the first region as "starts humongous". This
706 // will also update the BOT covering all the regions to reflect
707 // that there is a single object that starts at the bottom of the
708 // first region.
709 first_hr->set_startsHumongous(new_top, new_end);
710
711 // Then, if there are any, we will set up the "continues
712 // humongous" regions.
713 HeapRegion* hr = NULL;
714 for (uint i = first + 1; i < last; ++i) {
715 hr = region_at(i);
716 hr->set_continuesHumongous(first_hr);
717 }
718 // If we have "continues humongous" regions (hr != NULL), then the
719 // end of the last one should match new_end.
720 assert(hr == NULL || hr->end() == new_end, "sanity");
721
722 // Up to this point no concurrent thread would have been able to
723 // do any scanning on any region in this series. All the top
724 // fields still point to bottom, so the intersection between
725 // [bottom,top] and [card_start,card_end] will be empty. Before we
726 // update the top fields, we'll do a storestore to make sure that
727 // no thread sees the update to top before the zeroing of the
728 // object header and the BOT initialization.
729 OrderAccess::storestore();
730
731 // Now that the BOT and the object header have been initialized,
732 // we can update top of the "starts humongous" region.
733 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
734 "new_top should be in this region");
735 first_hr->set_top(new_top);
736 if (_hr_printer.is_active()) {
737 HeapWord* bottom = first_hr->bottom();
738 HeapWord* end = first_hr->orig_end();
739 if ((first + 1) == last) {
740 // the series has a single humongous region
741 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
742 } else {
743 // the series has more than one humongous regions
744 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
745 }
746 }
747
748 // Now, we will update the top fields of the "continues humongous"
749 // regions. The reason we need to do this is that, otherwise,
750 // these regions would look empty and this will confuse parts of
751 // G1. For example, the code that looks for a consecutive number
752 // of empty regions will consider them empty and try to
753 // re-allocate them. We can extend is_empty() to also include
754 // !continuesHumongous(), but it is easier to just update the top
755 // fields here. The way we set top for all regions (i.e., top ==
756 // end for all regions but the last one, top == new_top for the
757 // last one) is actually used when we will free up the humongous
758 // region in free_humongous_region().
759 hr = NULL;
760 for (uint i = first + 1; i < last; ++i) {
761 hr = region_at(i);
762 if ((i + 1) == last) {
763 // last continues humongous region
764 assert(hr->bottom() < new_top && new_top <= hr->end(),
765 "new_top should fall on this region");
766 hr->set_top(new_top);
767 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
768 } else {
769 // not last one
770 assert(new_top > hr->end(), "new_top should be above this region");
771 hr->set_top(hr->end());
772 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
773 }
774 }
775 // If we have continues humongous regions (hr != NULL), then the
776 // end of the last one should match new_end and its top should
777 // match new_top.
778 assert(hr == NULL ||
779 (hr->end() == new_end && hr->top() == new_top), "sanity");
780
781 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
782 _summary_bytes_used += first_hr->used();
783 _humongous_set.add(first_hr);
784
785 return new_obj;
786 }
787
788 // If could fit into free regions w/o expansion, try.
789 // Otherwise, if can expand, do so.
790 // Otherwise, if using ex regions might help, try with ex given back.
791 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
792 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
793
794 verify_region_sets_optional();
795
796 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
797 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
798 uint x_num = expansion_regions();
799 uint fs = _hrs.free_suffix();
800 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
801 if (first == G1_NULL_HRS_INDEX) {
802 // The only thing we can do now is attempt expansion.
803 if (fs + x_num >= num_regions) {
804 // If the number of regions we're trying to allocate for this
805 // object is at most the number of regions in the free suffix,
806 // then the call to humongous_obj_allocate_find_first() above
807 // should have succeeded and we wouldn't be here.
808 //
809 // We should only be trying to expand when the free suffix is
810 // not sufficient for the object _and_ we have some expansion
811 // room available.
812 assert(num_regions > fs, "earlier allocation should have succeeded");
813
814 ergo_verbose1(ErgoHeapSizing,
815 "attempt heap expansion",
816 ergo_format_reason("humongous allocation request failed")
817 ergo_format_byte("allocation request"),
818 word_size * HeapWordSize);
819 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
820 // Even though the heap was expanded, it might not have
821 // reached the desired size. So, we cannot assume that the
822 // allocation will succeed.
823 first = humongous_obj_allocate_find_first(num_regions, word_size);
824 }
825 }
826 }
827
828 HeapWord* result = NULL;
829 if (first != G1_NULL_HRS_INDEX) {
830 result =
831 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
832 assert(result != NULL, "it should always return a valid result");
833
834 // A successful humongous object allocation changes the used space
835 // information of the old generation so we need to recalculate the
836 // sizes and update the jstat counters here.
837 g1mm()->update_sizes();
838 }
839
840 verify_region_sets_optional();
841
842 return result;
843 }
844
845 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
846 assert_heap_not_locked_and_not_at_safepoint();
847 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
848
849 unsigned int dummy_gc_count_before;
850 int dummy_gclocker_retry_count = 0;
851 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
852 }
853
854 HeapWord*
855 G1CollectedHeap::mem_allocate(size_t word_size,
856 bool* gc_overhead_limit_was_exceeded) {
857 assert_heap_not_locked_and_not_at_safepoint();
858
859 // Loop until the allocation is satisfied, or unsatisfied after GC.
860 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
861 unsigned int gc_count_before;
862
863 HeapWord* result = NULL;
864 if (!isHumongous(word_size)) {
865 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
866 } else {
867 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
868 }
869 if (result != NULL) {
870 return result;
871 }
872
873 // Create the garbage collection operation...
874 VM_G1CollectForAllocation op(gc_count_before, word_size);
875 // ...and get the VM thread to execute it.
876 VMThread::execute(&op);
877
878 if (op.prologue_succeeded() && op.pause_succeeded()) {
879 // If the operation was successful we'll return the result even
880 // if it is NULL. If the allocation attempt failed immediately
881 // after a Full GC, it's unlikely we'll be able to allocate now.
882 HeapWord* result = op.result();
883 if (result != NULL && !isHumongous(word_size)) {
884 // Allocations that take place on VM operations do not do any
885 // card dirtying and we have to do it here. We only have to do
886 // this for non-humongous allocations, though.
887 dirty_young_block(result, word_size);
888 }
889 return result;
890 } else {
891 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
892 return NULL;
893 }
894 assert(op.result() == NULL,
895 "the result should be NULL if the VM op did not succeed");
896 }
897
898 // Give a warning if we seem to be looping forever.
899 if ((QueuedAllocationWarningCount > 0) &&
900 (try_count % QueuedAllocationWarningCount == 0)) {
901 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
902 }
903 }
904
905 ShouldNotReachHere();
906 return NULL;
907 }
908
909 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
910 unsigned int *gc_count_before_ret,
911 int* gclocker_retry_count_ret) {
912 // Make sure you read the note in attempt_allocation_humongous().
913
914 assert_heap_not_locked_and_not_at_safepoint();
915 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
916 "be called for humongous allocation requests");
917
918 // We should only get here after the first-level allocation attempt
919 // (attempt_allocation()) failed to allocate.
920
921 // We will loop until a) we manage to successfully perform the
922 // allocation or b) we successfully schedule a collection which
923 // fails to perform the allocation. b) is the only case when we'll
924 // return NULL.
925 HeapWord* result = NULL;
926 for (int try_count = 1; /* we'll return */; try_count += 1) {
927 bool should_try_gc;
928 unsigned int gc_count_before;
929
930 {
931 MutexLockerEx x(Heap_lock);
932
933 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
934 false /* bot_updates */);
935 if (result != NULL) {
936 return result;
937 }
938
939 // If we reach here, attempt_allocation_locked() above failed to
940 // allocate a new region. So the mutator alloc region should be NULL.
941 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
942
943 if (GC_locker::is_active_and_needs_gc()) {
944 if (g1_policy()->can_expand_young_list()) {
945 // No need for an ergo verbose message here,
946 // can_expand_young_list() does this when it returns true.
947 result = _mutator_alloc_region.attempt_allocation_force(word_size,
948 false /* bot_updates */);
949 if (result != NULL) {
950 return result;
951 }
952 }
953 should_try_gc = false;
954 } else {
955 // The GCLocker may not be active but the GCLocker initiated
956 // GC may not yet have been performed (GCLocker::needs_gc()
957 // returns true). In this case we do not try this GC and
958 // wait until the GCLocker initiated GC is performed, and
959 // then retry the allocation.
960 if (GC_locker::needs_gc()) {
961 should_try_gc = false;
962 } else {
963 // Read the GC count while still holding the Heap_lock.
964 gc_count_before = total_collections();
965 should_try_gc = true;
966 }
967 }
968 }
969
970 if (should_try_gc) {
971 bool succeeded;
972 result = do_collection_pause(word_size, gc_count_before, &succeeded,
973 GCCause::_g1_inc_collection_pause);
974 if (result != NULL) {
975 assert(succeeded, "only way to get back a non-NULL result");
976 return result;
977 }
978
979 if (succeeded) {
980 // If we get here we successfully scheduled a collection which
981 // failed to allocate. No point in trying to allocate
982 // further. We'll just return NULL.
983 MutexLockerEx x(Heap_lock);
984 *gc_count_before_ret = total_collections();
985 return NULL;
986 }
987 } else {
988 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
989 MutexLockerEx x(Heap_lock);
990 *gc_count_before_ret = total_collections();
991 return NULL;
992 }
993 // The GCLocker is either active or the GCLocker initiated
994 // GC has not yet been performed. Stall until it is and
995 // then retry the allocation.
996 GC_locker::stall_until_clear();
997 (*gclocker_retry_count_ret) += 1;
998 }
999
1000 // We can reach here if we were unsuccessful in scheduling a
1001 // collection (because another thread beat us to it) or if we were
1002 // stalled due to the GC locker. In either can we should retry the
1003 // allocation attempt in case another thread successfully
1004 // performed a collection and reclaimed enough space. We do the
1005 // first attempt (without holding the Heap_lock) here and the
1006 // follow-on attempt will be at the start of the next loop
1007 // iteration (after taking the Heap_lock).
1008 result = _mutator_alloc_region.attempt_allocation(word_size,
1009 false /* bot_updates */);
1010 if (result != NULL) {
1011 return result;
1012 }
1013
1014 // Give a warning if we seem to be looping forever.
1015 if ((QueuedAllocationWarningCount > 0) &&
1016 (try_count % QueuedAllocationWarningCount == 0)) {
1017 warning("G1CollectedHeap::attempt_allocation_slow() "
1018 "retries %d times", try_count);
1019 }
1020 }
1021
1022 ShouldNotReachHere();
1023 return NULL;
1024 }
1025
1026 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1027 unsigned int * gc_count_before_ret,
1028 int* gclocker_retry_count_ret) {
1029 // The structure of this method has a lot of similarities to
1030 // attempt_allocation_slow(). The reason these two were not merged
1031 // into a single one is that such a method would require several "if
1032 // allocation is not humongous do this, otherwise do that"
1033 // conditional paths which would obscure its flow. In fact, an early
1034 // version of this code did use a unified method which was harder to
1035 // follow and, as a result, it had subtle bugs that were hard to
1036 // track down. So keeping these two methods separate allows each to
1037 // be more readable. It will be good to keep these two in sync as
1038 // much as possible.
1039
1040 assert_heap_not_locked_and_not_at_safepoint();
1041 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1042 "should only be called for humongous allocations");
1043
1044 // Humongous objects can exhaust the heap quickly, so we should check if we
1045 // need to start a marking cycle at each humongous object allocation. We do
1046 // the check before we do the actual allocation. The reason for doing it
1047 // before the allocation is that we avoid having to keep track of the newly
1048 // allocated memory while we do a GC.
1049 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1050 word_size)) {
1051 collect(GCCause::_g1_humongous_allocation);
1052 }
1053
1054 // We will loop until a) we manage to successfully perform the
1055 // allocation or b) we successfully schedule a collection which
1056 // fails to perform the allocation. b) is the only case when we'll
1057 // return NULL.
1058 HeapWord* result = NULL;
1059 for (int try_count = 1; /* we'll return */; try_count += 1) {
1060 bool should_try_gc;
1061 unsigned int gc_count_before;
1062
1063 {
1064 MutexLockerEx x(Heap_lock);
1065
1066 // Given that humongous objects are not allocated in young
1067 // regions, we'll first try to do the allocation without doing a
1068 // collection hoping that there's enough space in the heap.
1069 result = humongous_obj_allocate(word_size);
1070 if (result != NULL) {
1071 return result;
1072 }
1073
1074 if (GC_locker::is_active_and_needs_gc()) {
1075 should_try_gc = false;
1076 } else {
1077 // The GCLocker may not be active but the GCLocker initiated
1078 // GC may not yet have been performed (GCLocker::needs_gc()
1079 // returns true). In this case we do not try this GC and
1080 // wait until the GCLocker initiated GC is performed, and
1081 // then retry the allocation.
1082 if (GC_locker::needs_gc()) {
1083 should_try_gc = false;
1084 } else {
1085 // Read the GC count while still holding the Heap_lock.
1086 gc_count_before = total_collections();
1087 should_try_gc = true;
1088 }
1089 }
1090 }
1091
1092 if (should_try_gc) {
1093 // If we failed to allocate the humongous object, we should try to
1094 // do a collection pause (if we're allowed) in case it reclaims
1095 // enough space for the allocation to succeed after the pause.
1096
1097 bool succeeded;
1098 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1099 GCCause::_g1_humongous_allocation);
1100 if (result != NULL) {
1101 assert(succeeded, "only way to get back a non-NULL result");
1102 return result;
1103 }
1104
1105 if (succeeded) {
1106 // If we get here we successfully scheduled a collection which
1107 // failed to allocate. No point in trying to allocate
1108 // further. We'll just return NULL.
1109 MutexLockerEx x(Heap_lock);
1110 *gc_count_before_ret = total_collections();
1111 return NULL;
1112 }
1113 } else {
1114 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1115 MutexLockerEx x(Heap_lock);
1116 *gc_count_before_ret = total_collections();
1117 return NULL;
1118 }
1119 // The GCLocker is either active or the GCLocker initiated
1120 // GC has not yet been performed. Stall until it is and
1121 // then retry the allocation.
1122 GC_locker::stall_until_clear();
1123 (*gclocker_retry_count_ret) += 1;
1124 }
1125
1126 // We can reach here if we were unsuccessful in scheduling a
1127 // collection (because another thread beat us to it) or if we were
1128 // stalled due to the GC locker. In either can we should retry the
1129 // allocation attempt in case another thread successfully
1130 // performed a collection and reclaimed enough space. Give a
1131 // warning if we seem to be looping forever.
1132
1133 if ((QueuedAllocationWarningCount > 0) &&
1134 (try_count % QueuedAllocationWarningCount == 0)) {
1135 warning("G1CollectedHeap::attempt_allocation_humongous() "
1136 "retries %d times", try_count);
1137 }
1138 }
1139
1140 ShouldNotReachHere();
1141 return NULL;
1142 }
1143
1144 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1145 bool expect_null_mutator_alloc_region) {
1146 assert_at_safepoint(true /* should_be_vm_thread */);
1147 assert(_mutator_alloc_region.get() == NULL ||
1148 !expect_null_mutator_alloc_region,
1149 "the current alloc region was unexpectedly found to be non-NULL");
1150
1151 if (!isHumongous(word_size)) {
1152 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1153 false /* bot_updates */);
1154 } else {
1155 HeapWord* result = humongous_obj_allocate(word_size);
1156 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1157 g1_policy()->set_initiate_conc_mark_if_possible();
1158 }
1159 return result;
1160 }
1161
1162 ShouldNotReachHere();
1163 }
1164
1165 class PostMCRemSetClearClosure: public HeapRegionClosure {
1166 G1CollectedHeap* _g1h;
1167 ModRefBarrierSet* _mr_bs;
1168 public:
1169 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1170 _g1h(g1h), _mr_bs(mr_bs) {}
1171
1172 bool doHeapRegion(HeapRegion* r) {
1173 HeapRegionRemSet* hrrs = r->rem_set();
1174
1175 if (r->continuesHumongous()) {
1176 // We'll assert that the strong code root list and RSet is empty
1177 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1178 assert(hrrs->occupied() == 0, "RSet should be empty");
1179 return false;
1180 }
1181
1182 _g1h->reset_gc_time_stamps(r);
1183 hrrs->clear();
1184 // You might think here that we could clear just the cards
1185 // corresponding to the used region. But no: if we leave a dirty card
1186 // in a region we might allocate into, then it would prevent that card
1187 // from being enqueued, and cause it to be missed.
1188 // Re: the performance cost: we shouldn't be doing full GC anyway!
1189 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1190
1191 return false;
1192 }
1193 };
1194
1195 void G1CollectedHeap::clear_rsets_post_compaction() {
1196 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1197 heap_region_iterate(&rs_clear);
1198 }
1199
1200 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1201 G1CollectedHeap* _g1h;
1202 UpdateRSOopClosure _cl;
1203 int _worker_i;
1204 public:
1205 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1206 _cl(g1->g1_rem_set(), worker_i),
1207 _worker_i(worker_i),
1208 _g1h(g1)
1209 { }
1210
1211 bool doHeapRegion(HeapRegion* r) {
1212 if (!r->continuesHumongous()) {
1213 _cl.set_from(r);
1214 r->oop_iterate(&_cl);
1215 }
1216 return false;
1217 }
1218 };
1219
1220 class ParRebuildRSTask: public AbstractGangTask {
1221 G1CollectedHeap* _g1;
1222 public:
1223 ParRebuildRSTask(G1CollectedHeap* g1)
1224 : AbstractGangTask("ParRebuildRSTask"),
1225 _g1(g1)
1226 { }
1227
1228 void work(uint worker_id) {
1229 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1230 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1231 _g1->workers()->active_workers(),
1232 HeapRegion::RebuildRSClaimValue);
1233 }
1234 };
1235
1236 class PostCompactionPrinterClosure: public HeapRegionClosure {
1237 private:
1238 G1HRPrinter* _hr_printer;
1239 public:
1240 bool doHeapRegion(HeapRegion* hr) {
1241 assert(!hr->is_young(), "not expecting to find young regions");
1242 // We only generate output for non-empty regions.
1243 if (!hr->is_empty()) {
1244 if (!hr->isHumongous()) {
1245 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1246 } else if (hr->startsHumongous()) {
1247 if (hr->region_num() == 1) {
1248 // single humongous region
1249 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1250 } else {
1251 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1252 }
1253 } else {
1254 assert(hr->continuesHumongous(), "only way to get here");
1255 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1256 }
1257 }
1258 return false;
1259 }
1260
1261 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1262 : _hr_printer(hr_printer) { }
1263 };
1264
1265 void G1CollectedHeap::print_hrs_post_compaction() {
1266 PostCompactionPrinterClosure cl(hr_printer());
1267 heap_region_iterate(&cl);
1268 }
1269
1270 bool G1CollectedHeap::do_collection(bool explicit_gc,
1271 bool clear_all_soft_refs,
1272 size_t word_size) {
1273 assert_at_safepoint(true /* should_be_vm_thread */);
1274
1275 if (GC_locker::check_active_before_gc()) {
1276 return false;
1277 }
1278
1279 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1280 gc_timer->register_gc_start();
1281
1282 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1283 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1284
1285 SvcGCMarker sgcm(SvcGCMarker::FULL);
1286 ResourceMark rm;
1287
1288 print_heap_before_gc();
1289 trace_heap_before_gc(gc_tracer);
1290
1291 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1292
1293 verify_region_sets_optional();
1294
1295 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1296 collector_policy()->should_clear_all_soft_refs();
1297
1298 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1299
1300 {
1301 IsGCActiveMark x;
1302
1303 // Timing
1304 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1305 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1306 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1307
1308 {
1309 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1310 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1311 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1312
1313 double start = os::elapsedTime();
1314 g1_policy()->record_full_collection_start();
1315
1316 // Note: When we have a more flexible GC logging framework that
1317 // allows us to add optional attributes to a GC log record we
1318 // could consider timing and reporting how long we wait in the
1319 // following two methods.
1320 wait_while_free_regions_coming();
1321 // If we start the compaction before the CM threads finish
1322 // scanning the root regions we might trip them over as we'll
1323 // be moving objects / updating references. So let's wait until
1324 // they are done. By telling them to abort, they should complete
1325 // early.
1326 _cm->root_regions()->abort();
1327 _cm->root_regions()->wait_until_scan_finished();
1328 append_secondary_free_list_if_not_empty_with_lock();
1329
1330 gc_prologue(true);
1331 increment_total_collections(true /* full gc */);
1332 increment_old_marking_cycles_started();
1333
1334 assert(used() == recalculate_used(), "Should be equal");
1335
1336 verify_before_gc();
1337
1338 pre_full_gc_dump(gc_timer);
1339
1340 COMPILER2_PRESENT(DerivedPointerTable::clear());
1341
1342 // Disable discovery and empty the discovered lists
1343 // for the CM ref processor.
1344 ref_processor_cm()->disable_discovery();
1345 ref_processor_cm()->abandon_partial_discovery();
1346 ref_processor_cm()->verify_no_references_recorded();
1347
1348 // Abandon current iterations of concurrent marking and concurrent
1349 // refinement, if any are in progress. We have to do this before
1350 // wait_until_scan_finished() below.
1351 concurrent_mark()->abort();
1352
1353 // Make sure we'll choose a new allocation region afterwards.
1354 release_mutator_alloc_region();
1355 abandon_gc_alloc_regions();
1356 g1_rem_set()->cleanupHRRS();
1357
1358 // We should call this after we retire any currently active alloc
1359 // regions so that all the ALLOC / RETIRE events are generated
1360 // before the start GC event.
1361 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1362
1363 // We may have added regions to the current incremental collection
1364 // set between the last GC or pause and now. We need to clear the
1365 // incremental collection set and then start rebuilding it afresh
1366 // after this full GC.
1367 abandon_collection_set(g1_policy()->inc_cset_head());
1368 g1_policy()->clear_incremental_cset();
1369 g1_policy()->stop_incremental_cset_building();
1370
1371 tear_down_region_sets(false /* free_list_only */);
1372 g1_policy()->set_gcs_are_young(true);
1373
1374 // See the comments in g1CollectedHeap.hpp and
1375 // G1CollectedHeap::ref_processing_init() about
1376 // how reference processing currently works in G1.
1377
1378 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1379 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1380
1381 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1382 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1383
1384 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1385 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1386
1387 // Do collection work
1388 {
1389 HandleMark hm; // Discard invalid handles created during gc
1390 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1391 }
1392
1393 assert(free_regions() == 0, "we should not have added any free regions");
1394 rebuild_region_sets(false /* free_list_only */);
1395
1396 // Enqueue any discovered reference objects that have
1397 // not been removed from the discovered lists.
1398 ref_processor_stw()->enqueue_discovered_references();
1399
1400 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1401
1402 MemoryService::track_memory_usage();
1403
1404 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1405 ref_processor_stw()->verify_no_references_recorded();
1406
1407 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1408 ClassLoaderDataGraph::purge();
1409 MetaspaceAux::verify_metrics();
1410
1411 // Note: since we've just done a full GC, concurrent
1412 // marking is no longer active. Therefore we need not
1413 // re-enable reference discovery for the CM ref processor.
1414 // That will be done at the start of the next marking cycle.
1415 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1416 ref_processor_cm()->verify_no_references_recorded();
1417
1418 reset_gc_time_stamp();
1419 // Since everything potentially moved, we will clear all remembered
1420 // sets, and clear all cards. Later we will rebuild remembered
1421 // sets. We will also reset the GC time stamps of the regions.
1422 clear_rsets_post_compaction();
1423 check_gc_time_stamps();
1424
1425 // Resize the heap if necessary.
1426 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1427
1428 if (_hr_printer.is_active()) {
1429 // We should do this after we potentially resize the heap so
1430 // that all the COMMIT / UNCOMMIT events are generated before
1431 // the end GC event.
1432
1433 print_hrs_post_compaction();
1434 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1435 }
1436
1437 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1438 if (hot_card_cache->use_cache()) {
1439 hot_card_cache->reset_card_counts();
1440 hot_card_cache->reset_hot_cache();
1441 }
1442
1443 // Rebuild remembered sets of all regions.
1444 if (G1CollectedHeap::use_parallel_gc_threads()) {
1445 uint n_workers =
1446 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1447 workers()->active_workers(),
1448 Threads::number_of_non_daemon_threads());
1449 assert(UseDynamicNumberOfGCThreads ||
1450 n_workers == workers()->total_workers(),
1451 "If not dynamic should be using all the workers");
1452 workers()->set_active_workers(n_workers);
1453 // Set parallel threads in the heap (_n_par_threads) only
1454 // before a parallel phase and always reset it to 0 after
1455 // the phase so that the number of parallel threads does
1456 // no get carried forward to a serial phase where there
1457 // may be code that is "possibly_parallel".
1458 set_par_threads(n_workers);
1459
1460 ParRebuildRSTask rebuild_rs_task(this);
1461 assert(check_heap_region_claim_values(
1462 HeapRegion::InitialClaimValue), "sanity check");
1463 assert(UseDynamicNumberOfGCThreads ||
1464 workers()->active_workers() == workers()->total_workers(),
1465 "Unless dynamic should use total workers");
1466 // Use the most recent number of active workers
1467 assert(workers()->active_workers() > 0,
1468 "Active workers not properly set");
1469 set_par_threads(workers()->active_workers());
1470 workers()->run_task(&rebuild_rs_task);
1471 set_par_threads(0);
1472 assert(check_heap_region_claim_values(
1473 HeapRegion::RebuildRSClaimValue), "sanity check");
1474 reset_heap_region_claim_values();
1475 } else {
1476 RebuildRSOutOfRegionClosure rebuild_rs(this);
1477 heap_region_iterate(&rebuild_rs);
1478 }
1479
1480 // Rebuild the strong code root lists for each region
1481 rebuild_strong_code_roots();
1482
1483 if (true) { // FIXME
1484 MetaspaceGC::compute_new_size();
1485 }
1486
1487 #ifdef TRACESPINNING
1488 ParallelTaskTerminator::print_termination_counts();
1489 #endif
1490
1491 // Discard all rset updates
1492 JavaThread::dirty_card_queue_set().abandon_logs();
1493 assert(!G1DeferredRSUpdate
1494 || (G1DeferredRSUpdate &&
1495 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1496
1497 _young_list->reset_sampled_info();
1498 // At this point there should be no regions in the
1499 // entire heap tagged as young.
1500 assert(check_young_list_empty(true /* check_heap */),
1501 "young list should be empty at this point");
1502
1503 // Update the number of full collections that have been completed.
1504 increment_old_marking_cycles_completed(false /* concurrent */);
1505
1506 _hrs.verify_optional();
1507 verify_region_sets_optional();
1508
1509 verify_after_gc();
1510
1511 // Start a new incremental collection set for the next pause
1512 assert(g1_policy()->collection_set() == NULL, "must be");
1513 g1_policy()->start_incremental_cset_building();
1514
1515 // Clear the _cset_fast_test bitmap in anticipation of adding
1516 // regions to the incremental collection set for the next
1517 // evacuation pause.
1518 clear_cset_fast_test();
1519
1520 init_mutator_alloc_region();
1521
1522 double end = os::elapsedTime();
1523 g1_policy()->record_full_collection_end();
1524
1525 if (G1Log::fine()) {
1526 g1_policy()->print_heap_transition();
1527 }
1528
1529 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1530 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1531 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1532 // before any GC notifications are raised.
1533 g1mm()->update_sizes();
1534
1535 gc_epilogue(true);
1536 }
1537
1538 if (G1Log::finer()) {
1539 g1_policy()->print_detailed_heap_transition(true /* full */);
1540 }
1541
1542 print_heap_after_gc();
1543 trace_heap_after_gc(gc_tracer);
1544
1545 post_full_gc_dump(gc_timer);
1546
1547 gc_timer->register_gc_end();
1548 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1549 }
1550
1551 return true;
1552 }
1553
1554 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1555 // do_collection() will return whether it succeeded in performing
1556 // the GC. Currently, there is no facility on the
1557 // do_full_collection() API to notify the caller than the collection
1558 // did not succeed (e.g., because it was locked out by the GC
1559 // locker). So, right now, we'll ignore the return value.
1560 bool dummy = do_collection(true, /* explicit_gc */
1561 clear_all_soft_refs,
1562 0 /* word_size */);
1563 }
1564
1565 // This code is mostly copied from TenuredGeneration.
1566 void
1567 G1CollectedHeap::
1568 resize_if_necessary_after_full_collection(size_t word_size) {
1569 // Include the current allocation, if any, and bytes that will be
1570 // pre-allocated to support collections, as "used".
1571 const size_t used_after_gc = used();
1572 const size_t capacity_after_gc = capacity();
1573 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1574
1575 // This is enforced in arguments.cpp.
1576 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1577 "otherwise the code below doesn't make sense");
1578
1579 // We don't have floating point command-line arguments
1580 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1581 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1582 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1583 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1584
1585 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1586 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1587
1588 // We have to be careful here as these two calculations can overflow
1589 // 32-bit size_t's.
1590 double used_after_gc_d = (double) used_after_gc;
1591 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1592 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1593
1594 // Let's make sure that they are both under the max heap size, which
1595 // by default will make them fit into a size_t.
1596 double desired_capacity_upper_bound = (double) max_heap_size;
1597 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1598 desired_capacity_upper_bound);
1599 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1600 desired_capacity_upper_bound);
1601
1602 // We can now safely turn them into size_t's.
1603 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1604 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1605
1606 // This assert only makes sense here, before we adjust them
1607 // with respect to the min and max heap size.
1608 assert(minimum_desired_capacity <= maximum_desired_capacity,
1609 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1610 "maximum_desired_capacity = "SIZE_FORMAT,
1611 minimum_desired_capacity, maximum_desired_capacity));
1612
1613 // Should not be greater than the heap max size. No need to adjust
1614 // it with respect to the heap min size as it's a lower bound (i.e.,
1615 // we'll try to make the capacity larger than it, not smaller).
1616 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1617 // Should not be less than the heap min size. No need to adjust it
1618 // with respect to the heap max size as it's an upper bound (i.e.,
1619 // we'll try to make the capacity smaller than it, not greater).
1620 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1621
1622 if (capacity_after_gc < minimum_desired_capacity) {
1623 // Don't expand unless it's significant
1624 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1625 ergo_verbose4(ErgoHeapSizing,
1626 "attempt heap expansion",
1627 ergo_format_reason("capacity lower than "
1628 "min desired capacity after Full GC")
1629 ergo_format_byte("capacity")
1630 ergo_format_byte("occupancy")
1631 ergo_format_byte_perc("min desired capacity"),
1632 capacity_after_gc, used_after_gc,
1633 minimum_desired_capacity, (double) MinHeapFreeRatio);
1634 expand(expand_bytes);
1635
1636 // No expansion, now see if we want to shrink
1637 } else if (capacity_after_gc > maximum_desired_capacity) {
1638 // Capacity too large, compute shrinking size
1639 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1640 ergo_verbose4(ErgoHeapSizing,
1641 "attempt heap shrinking",
1642 ergo_format_reason("capacity higher than "
1643 "max desired capacity after Full GC")
1644 ergo_format_byte("capacity")
1645 ergo_format_byte("occupancy")
1646 ergo_format_byte_perc("max desired capacity"),
1647 capacity_after_gc, used_after_gc,
1648 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1649 shrink(shrink_bytes);
1650 }
1651 }
1652
1653
1654 HeapWord*
1655 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1656 bool* succeeded) {
1657 assert_at_safepoint(true /* should_be_vm_thread */);
1658
1659 *succeeded = true;
1660 // Let's attempt the allocation first.
1661 HeapWord* result =
1662 attempt_allocation_at_safepoint(word_size,
1663 false /* expect_null_mutator_alloc_region */);
1664 if (result != NULL) {
1665 assert(*succeeded, "sanity");
1666 return result;
1667 }
1668
1669 // In a G1 heap, we're supposed to keep allocation from failing by
1670 // incremental pauses. Therefore, at least for now, we'll favor
1671 // expansion over collection. (This might change in the future if we can
1672 // do something smarter than full collection to satisfy a failed alloc.)
1673 result = expand_and_allocate(word_size);
1674 if (result != NULL) {
1675 assert(*succeeded, "sanity");
1676 return result;
1677 }
1678
1679 // Expansion didn't work, we'll try to do a Full GC.
1680 bool gc_succeeded = do_collection(false, /* explicit_gc */
1681 false, /* clear_all_soft_refs */
1682 word_size);
1683 if (!gc_succeeded) {
1684 *succeeded = false;
1685 return NULL;
1686 }
1687
1688 // Retry the allocation
1689 result = attempt_allocation_at_safepoint(word_size,
1690 true /* expect_null_mutator_alloc_region */);
1691 if (result != NULL) {
1692 assert(*succeeded, "sanity");
1693 return result;
1694 }
1695
1696 // Then, try a Full GC that will collect all soft references.
1697 gc_succeeded = do_collection(false, /* explicit_gc */
1698 true, /* clear_all_soft_refs */
1699 word_size);
1700 if (!gc_succeeded) {
1701 *succeeded = false;
1702 return NULL;
1703 }
1704
1705 // Retry the allocation once more
1706 result = attempt_allocation_at_safepoint(word_size,
1707 true /* expect_null_mutator_alloc_region */);
1708 if (result != NULL) {
1709 assert(*succeeded, "sanity");
1710 return result;
1711 }
1712
1713 assert(!collector_policy()->should_clear_all_soft_refs(),
1714 "Flag should have been handled and cleared prior to this point");
1715
1716 // What else? We might try synchronous finalization later. If the total
1717 // space available is large enough for the allocation, then a more
1718 // complete compaction phase than we've tried so far might be
1719 // appropriate.
1720 assert(*succeeded, "sanity");
1721 return NULL;
1722 }
1723
1724 // Attempting to expand the heap sufficiently
1725 // to support an allocation of the given "word_size". If
1726 // successful, perform the allocation and return the address of the
1727 // allocated block, or else "NULL".
1728
1729 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1730 assert_at_safepoint(true /* should_be_vm_thread */);
1731
1732 verify_region_sets_optional();
1733
1734 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1735 ergo_verbose1(ErgoHeapSizing,
1736 "attempt heap expansion",
1737 ergo_format_reason("allocation request failed")
1738 ergo_format_byte("allocation request"),
1739 word_size * HeapWordSize);
1740 if (expand(expand_bytes)) {
1741 _hrs.verify_optional();
1742 verify_region_sets_optional();
1743 return attempt_allocation_at_safepoint(word_size,
1744 false /* expect_null_mutator_alloc_region */);
1745 }
1746 return NULL;
1747 }
1748
1749 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1750 HeapWord* new_end) {
1751 assert(old_end != new_end, "don't call this otherwise");
1752 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1753
1754 // Update the committed mem region.
1755 _g1_committed.set_end(new_end);
1756 // Tell the card table about the update.
1757 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1758 // Tell the BOT about the update.
1759 _bot_shared->resize(_g1_committed.word_size());
1760 // Tell the hot card cache about the update
1761 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1762 }
1763
1764 bool G1CollectedHeap::expand(size_t expand_bytes) {
1765 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1766 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1767 HeapRegion::GrainBytes);
1768 ergo_verbose2(ErgoHeapSizing,
1769 "expand the heap",
1770 ergo_format_byte("requested expansion amount")
1771 ergo_format_byte("attempted expansion amount"),
1772 expand_bytes, aligned_expand_bytes);
1773
1774 if (_g1_storage.uncommitted_size() == 0) {
1775 ergo_verbose0(ErgoHeapSizing,
1776 "did not expand the heap",
1777 ergo_format_reason("heap already fully expanded"));
1778 return false;
1779 }
1780
1781 // First commit the memory.
1782 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1783 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1784 if (successful) {
1785 // Then propagate this update to the necessary data structures.
1786 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1787 update_committed_space(old_end, new_end);
1788
1789 FreeRegionList expansion_list("Local Expansion List");
1790 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1791 assert(mr.start() == old_end, "post-condition");
1792 // mr might be a smaller region than what was requested if
1793 // expand_by() was unable to allocate the HeapRegion instances
1794 assert(mr.end() <= new_end, "post-condition");
1795
1796 size_t actual_expand_bytes = mr.byte_size();
1797 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1798 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1799 "post-condition");
1800 if (actual_expand_bytes < aligned_expand_bytes) {
1801 // We could not expand _hrs to the desired size. In this case we
1802 // need to shrink the committed space accordingly.
1803 assert(mr.end() < new_end, "invariant");
1804
1805 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1806 // First uncommit the memory.
1807 _g1_storage.shrink_by(diff_bytes);
1808 // Then propagate this update to the necessary data structures.
1809 update_committed_space(new_end, mr.end());
1810 }
1811 _free_list.add_as_tail(&expansion_list);
1812
1813 if (_hr_printer.is_active()) {
1814 HeapWord* curr = mr.start();
1815 while (curr < mr.end()) {
1816 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1817 _hr_printer.commit(curr, curr_end);
1818 curr = curr_end;
1819 }
1820 assert(curr == mr.end(), "post-condition");
1821 }
1822 g1_policy()->record_new_heap_size(n_regions());
1823 } else {
1824 ergo_verbose0(ErgoHeapSizing,
1825 "did not expand the heap",
1826 ergo_format_reason("heap expansion operation failed"));
1827 // The expansion of the virtual storage space was unsuccessful.
1828 // Let's see if it was because we ran out of swap.
1829 if (G1ExitOnExpansionFailure &&
1830 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1831 // We had head room...
1832 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1833 }
1834 }
1835 return successful;
1836 }
1837
1838 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1839 size_t aligned_shrink_bytes =
1840 ReservedSpace::page_align_size_down(shrink_bytes);
1841 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1842 HeapRegion::GrainBytes);
1843 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1844
1845 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1846 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1847 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1848
1849 ergo_verbose3(ErgoHeapSizing,
1850 "shrink the heap",
1851 ergo_format_byte("requested shrinking amount")
1852 ergo_format_byte("aligned shrinking amount")
1853 ergo_format_byte("attempted shrinking amount"),
1854 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1855 if (num_regions_removed > 0) {
1856 _g1_storage.shrink_by(shrunk_bytes);
1857 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1858
1859 if (_hr_printer.is_active()) {
1860 HeapWord* curr = old_end;
1861 while (curr > new_end) {
1862 HeapWord* curr_end = curr;
1863 curr -= HeapRegion::GrainWords;
1864 _hr_printer.uncommit(curr, curr_end);
1865 }
1866 }
1867
1868 _expansion_regions += num_regions_removed;
1869 update_committed_space(old_end, new_end);
1870 HeapRegionRemSet::shrink_heap(n_regions());
1871 g1_policy()->record_new_heap_size(n_regions());
1872 } else {
1873 ergo_verbose0(ErgoHeapSizing,
1874 "did not shrink the heap",
1875 ergo_format_reason("heap shrinking operation failed"));
1876 }
1877 }
1878
1879 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1880 verify_region_sets_optional();
1881
1882 // We should only reach here at the end of a Full GC which means we
1883 // should not not be holding to any GC alloc regions. The method
1884 // below will make sure of that and do any remaining clean up.
1885 abandon_gc_alloc_regions();
1886
1887 // Instead of tearing down / rebuilding the free lists here, we
1888 // could instead use the remove_all_pending() method on free_list to
1889 // remove only the ones that we need to remove.
1890 tear_down_region_sets(true /* free_list_only */);
1891 shrink_helper(shrink_bytes);
1892 rebuild_region_sets(true /* free_list_only */);
1893
1894 _hrs.verify_optional();
1895 verify_region_sets_optional();
1896 }
1897
1898 // Public methods.
1899
1900 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1901 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1902 #endif // _MSC_VER
1903
1904
1905 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1906 SharedHeap(policy_),
1907 _g1_policy(policy_),
1908 _dirty_card_queue_set(false),
1909 _into_cset_dirty_card_queue_set(false),
1910 _is_alive_closure_cm(this),
1911 _is_alive_closure_stw(this),
1912 _ref_processor_cm(NULL),
1913 _ref_processor_stw(NULL),
1914 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1915 _bot_shared(NULL),
1916 _evac_failure_scan_stack(NULL),
1917 _mark_in_progress(false),
1918 _cg1r(NULL), _summary_bytes_used(0),
1919 _g1mm(NULL),
1920 _refine_cte_cl(NULL),
1921 _full_collection(false),
1922 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1923 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1924 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1925 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1926 _free_regions_coming(false),
1927 _young_list(new YoungList(this)),
1928 _gc_time_stamp(0),
1929 _retained_old_gc_alloc_region(NULL),
1930 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1931 _old_plab_stats(OldPLABSize, PLABWeight),
1932 _expand_heap_after_alloc_failure(true),
1933 _surviving_young_words(NULL),
1934 _old_marking_cycles_started(0),
1935 _old_marking_cycles_completed(0),
1936 _concurrent_cycle_started(false),
1937 _in_cset_fast_test(),
1938 _dirty_cards_region_list(NULL),
1939 _worker_cset_start_region(NULL),
1940 _worker_cset_start_region_time_stamp(NULL),
1941 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1942 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1943 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1944 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1945
1946 _g1h = this;
1947 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1948 vm_exit_during_initialization("Failed necessary allocation.");
1949 }
1950
1951 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1952
1953 int n_queues = MAX2((int)ParallelGCThreads, 1);
1954 _task_queues = new RefToScanQueueSet(n_queues);
1955
1956 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1957 assert(n_rem_sets > 0, "Invariant.");
1958
1959 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1960 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1961 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1962
1963 for (int i = 0; i < n_queues; i++) {
1964 RefToScanQueue* q = new RefToScanQueue();
1965 q->initialize();
1966 _task_queues->register_queue(i, q);
1967 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1968 }
1969 clear_cset_start_regions();
1970
1971 // Initialize the G1EvacuationFailureALot counters and flags.
1972 NOT_PRODUCT(reset_evacuation_should_fail();)
1973
1974 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1975 }
1976
1977 jint G1CollectedHeap::initialize() {
1978 CollectedHeap::pre_initialize();
1979 os::enable_vtime();
1980
1981 G1Log::init();
1982
1983 // Necessary to satisfy locking discipline assertions.
1984
1985 MutexLocker x(Heap_lock);
1986
1987 // We have to initialize the printer before committing the heap, as
1988 // it will be used then.
1989 _hr_printer.set_active(G1PrintHeapRegions);
1990
1991 // While there are no constraints in the GC code that HeapWordSize
1992 // be any particular value, there are multiple other areas in the
1993 // system which believe this to be true (e.g. oop->object_size in some
1994 // cases incorrectly returns the size in wordSize units rather than
1995 // HeapWordSize).
1996 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1997
1998 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1999 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2000 size_t heap_alignment = collector_policy()->heap_alignment();
2001
2002 // Ensure that the sizes are properly aligned.
2003 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2004 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2005 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2006
2007 _cg1r = new ConcurrentG1Refine(this);
2008
2009 // Reserve the maximum.
2010
2011 // When compressed oops are enabled, the preferred heap base
2012 // is calculated by subtracting the requested size from the
2013 // 32Gb boundary and using the result as the base address for
2014 // heap reservation. If the requested size is not aligned to
2015 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2016 // into the ReservedHeapSpace constructor) then the actual
2017 // base of the reserved heap may end up differing from the
2018 // address that was requested (i.e. the preferred heap base).
2019 // If this happens then we could end up using a non-optimal
2020 // compressed oops mode.
2021
2022 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2023 heap_alignment);
2024
2025 // It is important to do this in a way such that concurrent readers can't
2026 // temporarily think something is in the heap. (I've actually seen this
2027 // happen in asserts: DLD.)
2028 _reserved.set_word_size(0);
2029 _reserved.set_start((HeapWord*)heap_rs.base());
2030 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2031
2032 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2033
2034 // Create the gen rem set (and barrier set) for the entire reserved region.
2035 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2036 set_barrier_set(rem_set()->bs());
2037 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2038 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2039 return JNI_ENOMEM;
2040 }
2041
2042 // Also create a G1 rem set.
2043 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2044
2045 // Carve out the G1 part of the heap.
2046
2047 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2048 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2049 g1_rs.size()/HeapWordSize);
2050
2051 _g1_storage.initialize(g1_rs, 0);
2052 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2053 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2054 (HeapWord*) _g1_reserved.end());
2055 assert(_hrs.max_length() == _expansion_regions,
2056 err_msg("max length: %u expansion regions: %u",
2057 _hrs.max_length(), _expansion_regions));
2058
2059 // Do later initialization work for concurrent refinement.
2060 _cg1r->init();
2061
2062 // 6843694 - ensure that the maximum region index can fit
2063 // in the remembered set structures.
2064 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2065 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2066
2067 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2068 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2069 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2070 "too many cards per region");
2071
2072 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2073
2074 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2075 heap_word_size(init_byte_size));
2076
2077 _g1h = this;
2078
2079 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2080
2081 // Create the ConcurrentMark data structure and thread.
2082 // (Must do this late, so that "max_regions" is defined.)
2083 _cm = new ConcurrentMark(this, heap_rs);
2084 if (_cm == NULL || !_cm->completed_initialization()) {
2085 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2086 return JNI_ENOMEM;
2087 }
2088 _cmThread = _cm->cmThread();
2089
2090 // Initialize the from_card cache structure of HeapRegionRemSet.
2091 HeapRegionRemSet::init_heap(max_regions());
2092
2093 // Now expand into the initial heap size.
2094 if (!expand(init_byte_size)) {
2095 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2096 return JNI_ENOMEM;
2097 }
2098
2099 // Perform any initialization actions delegated to the policy.
2100 g1_policy()->init();
2101
2102 _refine_cte_cl =
2103 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2104 g1_rem_set(),
2105 concurrent_g1_refine());
2106 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2107
2108 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2109 SATB_Q_FL_lock,
2110 G1SATBProcessCompletedThreshold,
2111 Shared_SATB_Q_lock);
2112
2113 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2114 DirtyCardQ_FL_lock,
2115 concurrent_g1_refine()->yellow_zone(),
2116 concurrent_g1_refine()->red_zone(),
2117 Shared_DirtyCardQ_lock);
2118
2119 if (G1DeferredRSUpdate) {
2120 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2121 DirtyCardQ_FL_lock,
2122 -1, // never trigger processing
2123 -1, // no limit on length
2124 Shared_DirtyCardQ_lock,
2125 &JavaThread::dirty_card_queue_set());
2126 }
2127
2128 // Initialize the card queue set used to hold cards containing
2129 // references into the collection set.
2130 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2131 DirtyCardQ_FL_lock,
2132 -1, // never trigger processing
2133 -1, // no limit on length
2134 Shared_DirtyCardQ_lock,
2135 &JavaThread::dirty_card_queue_set());
2136
2137 // In case we're keeping closure specialization stats, initialize those
2138 // counts and that mechanism.
2139 SpecializationStats::clear();
2140
2141 // Here we allocate the dummy full region that is required by the
2142 // G1AllocRegion class. If we don't pass an address in the reserved
2143 // space here, lots of asserts fire.
2144
2145 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2146 _g1_reserved.start());
2147 // We'll re-use the same region whether the alloc region will
2148 // require BOT updates or not and, if it doesn't, then a non-young
2149 // region will complain that it cannot support allocations without
2150 // BOT updates. So we'll tag the dummy region as young to avoid that.
2151 dummy_region->set_young();
2152 // Make sure it's full.
2153 dummy_region->set_top(dummy_region->end());
2154 G1AllocRegion::setup(this, dummy_region);
2155
2156 init_mutator_alloc_region();
2157
2158 // Do create of the monitoring and management support so that
2159 // values in the heap have been properly initialized.
2160 _g1mm = new G1MonitoringSupport(this);
2161
2162 G1StringDedup::initialize();
2163
2164 return JNI_OK;
2165 }
2166
2167 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2168 return HeapRegion::max_region_size();
2169 }
2170
2171 void G1CollectedHeap::ref_processing_init() {
2172 // Reference processing in G1 currently works as follows:
2173 //
2174 // * There are two reference processor instances. One is
2175 // used to record and process discovered references
2176 // during concurrent marking; the other is used to
2177 // record and process references during STW pauses
2178 // (both full and incremental).
2179 // * Both ref processors need to 'span' the entire heap as
2180 // the regions in the collection set may be dotted around.
2181 //
2182 // * For the concurrent marking ref processor:
2183 // * Reference discovery is enabled at initial marking.
2184 // * Reference discovery is disabled and the discovered
2185 // references processed etc during remarking.
2186 // * Reference discovery is MT (see below).
2187 // * Reference discovery requires a barrier (see below).
2188 // * Reference processing may or may not be MT
2189 // (depending on the value of ParallelRefProcEnabled
2190 // and ParallelGCThreads).
2191 // * A full GC disables reference discovery by the CM
2192 // ref processor and abandons any entries on it's
2193 // discovered lists.
2194 //
2195 // * For the STW processor:
2196 // * Non MT discovery is enabled at the start of a full GC.
2197 // * Processing and enqueueing during a full GC is non-MT.
2198 // * During a full GC, references are processed after marking.
2199 //
2200 // * Discovery (may or may not be MT) is enabled at the start
2201 // of an incremental evacuation pause.
2202 // * References are processed near the end of a STW evacuation pause.
2203 // * For both types of GC:
2204 // * Discovery is atomic - i.e. not concurrent.
2205 // * Reference discovery will not need a barrier.
2206
2207 SharedHeap::ref_processing_init();
2208 MemRegion mr = reserved_region();
2209
2210 // Concurrent Mark ref processor
2211 _ref_processor_cm =
2212 new ReferenceProcessor(mr, // span
2213 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2214 // mt processing
2215 (int) ParallelGCThreads,
2216 // degree of mt processing
2217 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2218 // mt discovery
2219 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2220 // degree of mt discovery
2221 false,
2222 // Reference discovery is not atomic
2223 &_is_alive_closure_cm,
2224 // is alive closure
2225 // (for efficiency/performance)
2226 true);
2227 // Setting next fields of discovered
2228 // lists requires a barrier.
2229
2230 // STW ref processor
2231 _ref_processor_stw =
2232 new ReferenceProcessor(mr, // span
2233 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2234 // mt processing
2235 MAX2((int)ParallelGCThreads, 1),
2236 // degree of mt processing
2237 (ParallelGCThreads > 1),
2238 // mt discovery
2239 MAX2((int)ParallelGCThreads, 1),
2240 // degree of mt discovery
2241 true,
2242 // Reference discovery is atomic
2243 &_is_alive_closure_stw,
2244 // is alive closure
2245 // (for efficiency/performance)
2246 false);
2247 // Setting next fields of discovered
2248 // lists does not require a barrier.
2249 }
2250
2251 size_t G1CollectedHeap::capacity() const {
2252 return _g1_committed.byte_size();
2253 }
2254
2255 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2256 assert(!hr->continuesHumongous(), "pre-condition");
2257 hr->reset_gc_time_stamp();
2258 if (hr->startsHumongous()) {
2259 uint first_index = hr->hrs_index() + 1;
2260 uint last_index = hr->last_hc_index();
2261 for (uint i = first_index; i < last_index; i += 1) {
2262 HeapRegion* chr = region_at(i);
2263 assert(chr->continuesHumongous(), "sanity");
2264 chr->reset_gc_time_stamp();
2265 }
2266 }
2267 }
2268
2269 #ifndef PRODUCT
2270 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2271 private:
2272 unsigned _gc_time_stamp;
2273 bool _failures;
2274
2275 public:
2276 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2277 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2278
2279 virtual bool doHeapRegion(HeapRegion* hr) {
2280 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2281 if (_gc_time_stamp != region_gc_time_stamp) {
2282 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2283 "expected %d", HR_FORMAT_PARAMS(hr),
2284 region_gc_time_stamp, _gc_time_stamp);
2285 _failures = true;
2286 }
2287 return false;
2288 }
2289
2290 bool failures() { return _failures; }
2291 };
2292
2293 void G1CollectedHeap::check_gc_time_stamps() {
2294 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2295 heap_region_iterate(&cl);
2296 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2297 }
2298 #endif // PRODUCT
2299
2300 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2301 DirtyCardQueue* into_cset_dcq,
2302 bool concurrent,
2303 uint worker_i) {
2304 // Clean cards in the hot card cache
2305 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2306 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2307
2308 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2309 int n_completed_buffers = 0;
2310 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2311 n_completed_buffers++;
2312 }
2313 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2314 dcqs.clear_n_completed_buffers();
2315 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2316 }
2317
2318
2319 // Computes the sum of the storage used by the various regions.
2320
2321 size_t G1CollectedHeap::used() const {
2322 assert(Heap_lock->owner() != NULL,
2323 "Should be owned on this thread's behalf.");
2324 size_t result = _summary_bytes_used;
2325 // Read only once in case it is set to NULL concurrently
2326 HeapRegion* hr = _mutator_alloc_region.get();
2327 if (hr != NULL)
2328 result += hr->used();
2329 return result;
2330 }
2331
2332 size_t G1CollectedHeap::used_unlocked() const {
2333 size_t result = _summary_bytes_used;
2334 return result;
2335 }
2336
2337 class SumUsedClosure: public HeapRegionClosure {
2338 size_t _used;
2339 public:
2340 SumUsedClosure() : _used(0) {}
2341 bool doHeapRegion(HeapRegion* r) {
2342 if (!r->continuesHumongous()) {
2343 _used += r->used();
2344 }
2345 return false;
2346 }
2347 size_t result() { return _used; }
2348 };
2349
2350 size_t G1CollectedHeap::recalculate_used() const {
2351 double recalculate_used_start = os::elapsedTime();
2352
2353 SumUsedClosure blk;
2354 heap_region_iterate(&blk);
2355
2356 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2357 return blk.result();
2358 }
2359
2360 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2361 switch (cause) {
2362 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2363 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2364 case GCCause::_g1_humongous_allocation: return true;
2365 default: return false;
2366 }
2367 }
2368
2369 #ifndef PRODUCT
2370 void G1CollectedHeap::allocate_dummy_regions() {
2371 // Let's fill up most of the region
2372 size_t word_size = HeapRegion::GrainWords - 1024;
2373 // And as a result the region we'll allocate will be humongous.
2374 guarantee(isHumongous(word_size), "sanity");
2375
2376 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2377 // Let's use the existing mechanism for the allocation
2378 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2379 if (dummy_obj != NULL) {
2380 MemRegion mr(dummy_obj, word_size);
2381 CollectedHeap::fill_with_object(mr);
2382 } else {
2383 // If we can't allocate once, we probably cannot allocate
2384 // again. Let's get out of the loop.
2385 break;
2386 }
2387 }
2388 }
2389 #endif // !PRODUCT
2390
2391 void G1CollectedHeap::increment_old_marking_cycles_started() {
2392 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2393 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2394 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2395 _old_marking_cycles_started, _old_marking_cycles_completed));
2396
2397 _old_marking_cycles_started++;
2398 }
2399
2400 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2401 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2402
2403 // We assume that if concurrent == true, then the caller is a
2404 // concurrent thread that was joined the Suspendible Thread
2405 // Set. If there's ever a cheap way to check this, we should add an
2406 // assert here.
2407
2408 // Given that this method is called at the end of a Full GC or of a
2409 // concurrent cycle, and those can be nested (i.e., a Full GC can
2410 // interrupt a concurrent cycle), the number of full collections
2411 // completed should be either one (in the case where there was no
2412 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2413 // behind the number of full collections started.
2414
2415 // This is the case for the inner caller, i.e. a Full GC.
2416 assert(concurrent ||
2417 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2418 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2419 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2420 "is inconsistent with _old_marking_cycles_completed = %u",
2421 _old_marking_cycles_started, _old_marking_cycles_completed));
2422
2423 // This is the case for the outer caller, i.e. the concurrent cycle.
2424 assert(!concurrent ||
2425 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2426 err_msg("for outer caller (concurrent cycle): "
2427 "_old_marking_cycles_started = %u "
2428 "is inconsistent with _old_marking_cycles_completed = %u",
2429 _old_marking_cycles_started, _old_marking_cycles_completed));
2430
2431 _old_marking_cycles_completed += 1;
2432
2433 // We need to clear the "in_progress" flag in the CM thread before
2434 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2435 // is set) so that if a waiter requests another System.gc() it doesn't
2436 // incorrectly see that a marking cycle is still in progress.
2437 if (concurrent) {
2438 _cmThread->clear_in_progress();
2439 }
2440
2441 // This notify_all() will ensure that a thread that called
2442 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2443 // and it's waiting for a full GC to finish will be woken up. It is
2444 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2445 FullGCCount_lock->notify_all();
2446 }
2447
2448 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2449 _concurrent_cycle_started = true;
2450 _gc_timer_cm->register_gc_start(start_time);
2451
2452 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2453 trace_heap_before_gc(_gc_tracer_cm);
2454 }
2455
2456 void G1CollectedHeap::register_concurrent_cycle_end() {
2457 if (_concurrent_cycle_started) {
2458 if (_cm->has_aborted()) {
2459 _gc_tracer_cm->report_concurrent_mode_failure();
2460 }
2461
2462 _gc_timer_cm->register_gc_end();
2463 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2464
2465 _concurrent_cycle_started = false;
2466 }
2467 }
2468
2469 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2470 if (_concurrent_cycle_started) {
2471 trace_heap_after_gc(_gc_tracer_cm);
2472 }
2473 }
2474
2475 G1YCType G1CollectedHeap::yc_type() {
2476 bool is_young = g1_policy()->gcs_are_young();
2477 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2478 bool is_during_mark = mark_in_progress();
2479
2480 if (is_initial_mark) {
2481 return InitialMark;
2482 } else if (is_during_mark) {
2483 return DuringMark;
2484 } else if (is_young) {
2485 return Normal;
2486 } else {
2487 return Mixed;
2488 }
2489 }
2490
2491 void G1CollectedHeap::collect(GCCause::Cause cause) {
2492 assert_heap_not_locked();
2493
2494 unsigned int gc_count_before;
2495 unsigned int old_marking_count_before;
2496 bool retry_gc;
2497
2498 do {
2499 retry_gc = false;
2500
2501 {
2502 MutexLocker ml(Heap_lock);
2503
2504 // Read the GC count while holding the Heap_lock
2505 gc_count_before = total_collections();
2506 old_marking_count_before = _old_marking_cycles_started;
2507 }
2508
2509 if (should_do_concurrent_full_gc(cause)) {
2510 // Schedule an initial-mark evacuation pause that will start a
2511 // concurrent cycle. We're setting word_size to 0 which means that
2512 // we are not requesting a post-GC allocation.
2513 VM_G1IncCollectionPause op(gc_count_before,
2514 0, /* word_size */
2515 true, /* should_initiate_conc_mark */
2516 g1_policy()->max_pause_time_ms(),
2517 cause);
2518
2519 VMThread::execute(&op);
2520 if (!op.pause_succeeded()) {
2521 if (old_marking_count_before == _old_marking_cycles_started) {
2522 retry_gc = op.should_retry_gc();
2523 } else {
2524 // A Full GC happened while we were trying to schedule the
2525 // initial-mark GC. No point in starting a new cycle given
2526 // that the whole heap was collected anyway.
2527 }
2528
2529 if (retry_gc) {
2530 if (GC_locker::is_active_and_needs_gc()) {
2531 GC_locker::stall_until_clear();
2532 }
2533 }
2534 }
2535 } else {
2536 if (cause == GCCause::_gc_locker
2537 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2538
2539 // Schedule a standard evacuation pause. We're setting word_size
2540 // to 0 which means that we are not requesting a post-GC allocation.
2541 VM_G1IncCollectionPause op(gc_count_before,
2542 0, /* word_size */
2543 false, /* should_initiate_conc_mark */
2544 g1_policy()->max_pause_time_ms(),
2545 cause);
2546 VMThread::execute(&op);
2547 } else {
2548 // Schedule a Full GC.
2549 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2550 VMThread::execute(&op);
2551 }
2552 }
2553 } while (retry_gc);
2554 }
2555
2556 bool G1CollectedHeap::is_in(const void* p) const {
2557 if (_g1_committed.contains(p)) {
2558 // Given that we know that p is in the committed space,
2559 // heap_region_containing_raw() should successfully
2560 // return the containing region.
2561 HeapRegion* hr = heap_region_containing_raw(p);
2562 return hr->is_in(p);
2563 } else {
2564 return false;
2565 }
2566 }
2567
2568 // Iteration functions.
2569
2570 // Iterates an OopClosure over all ref-containing fields of objects
2571 // within a HeapRegion.
2572
2573 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2574 MemRegion _mr;
2575 ExtendedOopClosure* _cl;
2576 public:
2577 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2578 : _mr(mr), _cl(cl) {}
2579 bool doHeapRegion(HeapRegion* r) {
2580 if (!r->continuesHumongous()) {
2581 r->oop_iterate(_cl);
2582 }
2583 return false;
2584 }
2585 };
2586
2587 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2588 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2589 heap_region_iterate(&blk);
2590 }
2591
2592 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2593 IterateOopClosureRegionClosure blk(mr, cl);
2594 heap_region_iterate(&blk);
2595 }
2596
2597 // Iterates an ObjectClosure over all objects within a HeapRegion.
2598
2599 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2600 ObjectClosure* _cl;
2601 public:
2602 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2603 bool doHeapRegion(HeapRegion* r) {
2604 if (! r->continuesHumongous()) {
2605 r->object_iterate(_cl);
2606 }
2607 return false;
2608 }
2609 };
2610
2611 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2612 IterateObjectClosureRegionClosure blk(cl);
2613 heap_region_iterate(&blk);
2614 }
2615
2616 // Calls a SpaceClosure on a HeapRegion.
2617
2618 class SpaceClosureRegionClosure: public HeapRegionClosure {
2619 SpaceClosure* _cl;
2620 public:
2621 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2622 bool doHeapRegion(HeapRegion* r) {
2623 _cl->do_space(r);
2624 return false;
2625 }
2626 };
2627
2628 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2629 SpaceClosureRegionClosure blk(cl);
2630 heap_region_iterate(&blk);
2631 }
2632
2633 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2634 _hrs.iterate(cl);
2635 }
2636
2637 void
2638 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2639 uint worker_id,
2640 uint no_of_par_workers,
2641 jint claim_value) {
2642 const uint regions = n_regions();
2643 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2644 no_of_par_workers :
2645 1);
2646 assert(UseDynamicNumberOfGCThreads ||
2647 no_of_par_workers == workers()->total_workers(),
2648 "Non dynamic should use fixed number of workers");
2649 // try to spread out the starting points of the workers
2650 const HeapRegion* start_hr =
2651 start_region_for_worker(worker_id, no_of_par_workers);
2652 const uint start_index = start_hr->hrs_index();
2653
2654 // each worker will actually look at all regions
2655 for (uint count = 0; count < regions; ++count) {
2656 const uint index = (start_index + count) % regions;
2657 assert(0 <= index && index < regions, "sanity");
2658 HeapRegion* r = region_at(index);
2659 // we'll ignore "continues humongous" regions (we'll process them
2660 // when we come across their corresponding "start humongous"
2661 // region) and regions already claimed
2662 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2663 continue;
2664 }
2665 // OK, try to claim it
2666 if (r->claimHeapRegion(claim_value)) {
2667 // success!
2668 assert(!r->continuesHumongous(), "sanity");
2669 if (r->startsHumongous()) {
2670 // If the region is "starts humongous" we'll iterate over its
2671 // "continues humongous" first; in fact we'll do them
2672 // first. The order is important. In on case, calling the
2673 // closure on the "starts humongous" region might de-allocate
2674 // and clear all its "continues humongous" regions and, as a
2675 // result, we might end up processing them twice. So, we'll do
2676 // them first (notice: most closures will ignore them anyway) and
2677 // then we'll do the "starts humongous" region.
2678 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2679 HeapRegion* chr = region_at(ch_index);
2680
2681 // if the region has already been claimed or it's not
2682 // "continues humongous" we're done
2683 if (chr->claim_value() == claim_value ||
2684 !chr->continuesHumongous()) {
2685 break;
2686 }
2687
2688 // No one should have claimed it directly. We can given
2689 // that we claimed its "starts humongous" region.
2690 assert(chr->claim_value() != claim_value, "sanity");
2691 assert(chr->humongous_start_region() == r, "sanity");
2692
2693 if (chr->claimHeapRegion(claim_value)) {
2694 // we should always be able to claim it; no one else should
2695 // be trying to claim this region
2696
2697 bool res2 = cl->doHeapRegion(chr);
2698 assert(!res2, "Should not abort");
2699
2700 // Right now, this holds (i.e., no closure that actually
2701 // does something with "continues humongous" regions
2702 // clears them). We might have to weaken it in the future,
2703 // but let's leave these two asserts here for extra safety.
2704 assert(chr->continuesHumongous(), "should still be the case");
2705 assert(chr->humongous_start_region() == r, "sanity");
2706 } else {
2707 guarantee(false, "we should not reach here");
2708 }
2709 }
2710 }
2711
2712 assert(!r->continuesHumongous(), "sanity");
2713 bool res = cl->doHeapRegion(r);
2714 assert(!res, "Should not abort");
2715 }
2716 }
2717 }
2718
2719 class ResetClaimValuesClosure: public HeapRegionClosure {
2720 public:
2721 bool doHeapRegion(HeapRegion* r) {
2722 r->set_claim_value(HeapRegion::InitialClaimValue);
2723 return false;
2724 }
2725 };
2726
2727 void G1CollectedHeap::reset_heap_region_claim_values() {
2728 ResetClaimValuesClosure blk;
2729 heap_region_iterate(&blk);
2730 }
2731
2732 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2733 ResetClaimValuesClosure blk;
2734 collection_set_iterate(&blk);
2735 }
2736
2737 #ifdef ASSERT
2738 // This checks whether all regions in the heap have the correct claim
2739 // value. I also piggy-backed on this a check to ensure that the
2740 // humongous_start_region() information on "continues humongous"
2741 // regions is correct.
2742
2743 class CheckClaimValuesClosure : public HeapRegionClosure {
2744 private:
2745 jint _claim_value;
2746 uint _failures;
2747 HeapRegion* _sh_region;
2748
2749 public:
2750 CheckClaimValuesClosure(jint claim_value) :
2751 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2752 bool doHeapRegion(HeapRegion* r) {
2753 if (r->claim_value() != _claim_value) {
2754 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2755 "claim value = %d, should be %d",
2756 HR_FORMAT_PARAMS(r),
2757 r->claim_value(), _claim_value);
2758 ++_failures;
2759 }
2760 if (!r->isHumongous()) {
2761 _sh_region = NULL;
2762 } else if (r->startsHumongous()) {
2763 _sh_region = r;
2764 } else if (r->continuesHumongous()) {
2765 if (r->humongous_start_region() != _sh_region) {
2766 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2767 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2768 HR_FORMAT_PARAMS(r),
2769 r->humongous_start_region(),
2770 _sh_region);
2771 ++_failures;
2772 }
2773 }
2774 return false;
2775 }
2776 uint failures() { return _failures; }
2777 };
2778
2779 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2780 CheckClaimValuesClosure cl(claim_value);
2781 heap_region_iterate(&cl);
2782 return cl.failures() == 0;
2783 }
2784
2785 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2786 private:
2787 jint _claim_value;
2788 uint _failures;
2789
2790 public:
2791 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2792 _claim_value(claim_value), _failures(0) { }
2793
2794 uint failures() { return _failures; }
2795
2796 bool doHeapRegion(HeapRegion* hr) {
2797 assert(hr->in_collection_set(), "how?");
2798 assert(!hr->isHumongous(), "H-region in CSet");
2799 if (hr->claim_value() != _claim_value) {
2800 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2801 "claim value = %d, should be %d",
2802 HR_FORMAT_PARAMS(hr),
2803 hr->claim_value(), _claim_value);
2804 _failures += 1;
2805 }
2806 return false;
2807 }
2808 };
2809
2810 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2811 CheckClaimValuesInCSetHRClosure cl(claim_value);
2812 collection_set_iterate(&cl);
2813 return cl.failures() == 0;
2814 }
2815 #endif // ASSERT
2816
2817 // Clear the cached CSet starting regions and (more importantly)
2818 // the time stamps. Called when we reset the GC time stamp.
2819 void G1CollectedHeap::clear_cset_start_regions() {
2820 assert(_worker_cset_start_region != NULL, "sanity");
2821 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2822
2823 int n_queues = MAX2((int)ParallelGCThreads, 1);
2824 for (int i = 0; i < n_queues; i++) {
2825 _worker_cset_start_region[i] = NULL;
2826 _worker_cset_start_region_time_stamp[i] = 0;
2827 }
2828 }
2829
2830 // Given the id of a worker, obtain or calculate a suitable
2831 // starting region for iterating over the current collection set.
2832 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2833 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2834
2835 HeapRegion* result = NULL;
2836 unsigned gc_time_stamp = get_gc_time_stamp();
2837
2838 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2839 // Cached starting region for current worker was set
2840 // during the current pause - so it's valid.
2841 // Note: the cached starting heap region may be NULL
2842 // (when the collection set is empty).
2843 result = _worker_cset_start_region[worker_i];
2844 assert(result == NULL || result->in_collection_set(), "sanity");
2845 return result;
2846 }
2847
2848 // The cached entry was not valid so let's calculate
2849 // a suitable starting heap region for this worker.
2850
2851 // We want the parallel threads to start their collection
2852 // set iteration at different collection set regions to
2853 // avoid contention.
2854 // If we have:
2855 // n collection set regions
2856 // p threads
2857 // Then thread t will start at region floor ((t * n) / p)
2858
2859 result = g1_policy()->collection_set();
2860 if (G1CollectedHeap::use_parallel_gc_threads()) {
2861 uint cs_size = g1_policy()->cset_region_length();
2862 uint active_workers = workers()->active_workers();
2863 assert(UseDynamicNumberOfGCThreads ||
2864 active_workers == workers()->total_workers(),
2865 "Unless dynamic should use total workers");
2866
2867 uint end_ind = (cs_size * worker_i) / active_workers;
2868 uint start_ind = 0;
2869
2870 if (worker_i > 0 &&
2871 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2872 // Previous workers starting region is valid
2873 // so let's iterate from there
2874 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2875 result = _worker_cset_start_region[worker_i - 1];
2876 }
2877
2878 for (uint i = start_ind; i < end_ind; i++) {
2879 result = result->next_in_collection_set();
2880 }
2881 }
2882
2883 // Note: the calculated starting heap region may be NULL
2884 // (when the collection set is empty).
2885 assert(result == NULL || result->in_collection_set(), "sanity");
2886 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2887 "should be updated only once per pause");
2888 _worker_cset_start_region[worker_i] = result;
2889 OrderAccess::storestore();
2890 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2891 return result;
2892 }
2893
2894 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2895 uint no_of_par_workers) {
2896 uint worker_num =
2897 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2898 assert(UseDynamicNumberOfGCThreads ||
2899 no_of_par_workers == workers()->total_workers(),
2900 "Non dynamic should use fixed number of workers");
2901 const uint start_index = n_regions() * worker_i / worker_num;
2902 return region_at(start_index);
2903 }
2904
2905 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2906 HeapRegion* r = g1_policy()->collection_set();
2907 while (r != NULL) {
2908 HeapRegion* next = r->next_in_collection_set();
2909 if (cl->doHeapRegion(r)) {
2910 cl->incomplete();
2911 return;
2912 }
2913 r = next;
2914 }
2915 }
2916
2917 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2918 HeapRegionClosure *cl) {
2919 if (r == NULL) {
2920 // The CSet is empty so there's nothing to do.
2921 return;
2922 }
2923
2924 assert(r->in_collection_set(),
2925 "Start region must be a member of the collection set.");
2926 HeapRegion* cur = r;
2927 while (cur != NULL) {
2928 HeapRegion* next = cur->next_in_collection_set();
2929 if (cl->doHeapRegion(cur) && false) {
2930 cl->incomplete();
2931 return;
2932 }
2933 cur = next;
2934 }
2935 cur = g1_policy()->collection_set();
2936 while (cur != r) {
2937 HeapRegion* next = cur->next_in_collection_set();
2938 if (cl->doHeapRegion(cur) && false) {
2939 cl->incomplete();
2940 return;
2941 }
2942 cur = next;
2943 }
2944 }
2945
2946 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2947 return n_regions() > 0 ? region_at(0) : NULL;
2948 }
2949
2950
2951 Space* G1CollectedHeap::space_containing(const void* addr) const {
2952 Space* res = heap_region_containing(addr);
2953 return res;
2954 }
2955
2956 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2957 Space* sp = space_containing(addr);
2958 if (sp != NULL) {
2959 return sp->block_start(addr);
2960 }
2961 return NULL;
2962 }
2963
2964 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2965 Space* sp = space_containing(addr);
2966 assert(sp != NULL, "block_size of address outside of heap");
2967 return sp->block_size(addr);
2968 }
2969
2970 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2971 Space* sp = space_containing(addr);
2972 return sp->block_is_obj(addr);
2973 }
2974
2975 bool G1CollectedHeap::supports_tlab_allocation() const {
2976 return true;
2977 }
2978
2979 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2980 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2981 }
2982
2983 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2984 return young_list()->eden_used_bytes();
2985 }
2986
2987 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2988 // must be smaller than the humongous object limit.
2989 size_t G1CollectedHeap::max_tlab_size() const {
2990 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2991 }
2992
2993 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2994 // Return the remaining space in the cur alloc region, but not less than
2995 // the min TLAB size.
2996
2997 // Also, this value can be at most the humongous object threshold,
2998 // since we can't allow tlabs to grow big enough to accommodate
2999 // humongous objects.
3000
3001 HeapRegion* hr = _mutator_alloc_region.get();
3002 size_t max_tlab = max_tlab_size() * wordSize;
3003 if (hr == NULL) {
3004 return max_tlab;
3005 } else {
3006 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3007 }
3008 }
3009
3010 size_t G1CollectedHeap::max_capacity() const {
3011 return _g1_reserved.byte_size();
3012 }
3013
3014 jlong G1CollectedHeap::millis_since_last_gc() {
3015 // assert(false, "NYI");
3016 return 0;
3017 }
3018
3019 void G1CollectedHeap::prepare_for_verify() {
3020 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3021 ensure_parsability(false);
3022 }
3023 g1_rem_set()->prepare_for_verify();
3024 }
3025
3026 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3027 VerifyOption vo) {
3028 switch (vo) {
3029 case VerifyOption_G1UsePrevMarking:
3030 return hr->obj_allocated_since_prev_marking(obj);
3031 case VerifyOption_G1UseNextMarking:
3032 return hr->obj_allocated_since_next_marking(obj);
3033 case VerifyOption_G1UseMarkWord:
3034 return false;
3035 default:
3036 ShouldNotReachHere();
3037 }
3038 return false; // keep some compilers happy
3039 }
3040
3041 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3042 switch (vo) {
3043 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3044 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3045 case VerifyOption_G1UseMarkWord: return NULL;
3046 default: ShouldNotReachHere();
3047 }
3048 return NULL; // keep some compilers happy
3049 }
3050
3051 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3052 switch (vo) {
3053 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3054 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3055 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3056 default: ShouldNotReachHere();
3057 }
3058 return false; // keep some compilers happy
3059 }
3060
3061 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3062 switch (vo) {
3063 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3064 case VerifyOption_G1UseNextMarking: return "NTAMS";
3065 case VerifyOption_G1UseMarkWord: return "NONE";
3066 default: ShouldNotReachHere();
3067 }
3068 return NULL; // keep some compilers happy
3069 }
3070
3071 class VerifyRootsClosure: public OopClosure {
3072 private:
3073 G1CollectedHeap* _g1h;
3074 VerifyOption _vo;
3075 bool _failures;
3076 public:
3077 // _vo == UsePrevMarking -> use "prev" marking information,
3078 // _vo == UseNextMarking -> use "next" marking information,
3079 // _vo == UseMarkWord -> use mark word from object header.
3080 VerifyRootsClosure(VerifyOption vo) :
3081 _g1h(G1CollectedHeap::heap()),
3082 _vo(vo),
3083 _failures(false) { }
3084
3085 bool failures() { return _failures; }
3086
3087 template <class T> void do_oop_nv(T* p) {
3088 T heap_oop = oopDesc::load_heap_oop(p);
3089 if (!oopDesc::is_null(heap_oop)) {
3090 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3091 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3092 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3093 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3094 if (_vo == VerifyOption_G1UseMarkWord) {
3095 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3096 }
3097 obj->print_on(gclog_or_tty);
3098 _failures = true;
3099 }
3100 }
3101 }
3102
3103 void do_oop(oop* p) { do_oop_nv(p); }
3104 void do_oop(narrowOop* p) { do_oop_nv(p); }
3105 };
3106
3107 class G1VerifyCodeRootOopClosure: public OopClosure {
3108 G1CollectedHeap* _g1h;
3109 OopClosure* _root_cl;
3110 nmethod* _nm;
3111 VerifyOption _vo;
3112 bool _failures;
3113
3114 template <class T> void do_oop_work(T* p) {
3115 // First verify that this root is live
3116 _root_cl->do_oop(p);
3117
3118 if (!G1VerifyHeapRegionCodeRoots) {
3119 // We're not verifying the code roots attached to heap region.
3120 return;
3121 }
3122
3123 // Don't check the code roots during marking verification in a full GC
3124 if (_vo == VerifyOption_G1UseMarkWord) {
3125 return;
3126 }
3127
3128 // Now verify that the current nmethod (which contains p) is
3129 // in the code root list of the heap region containing the
3130 // object referenced by p.
3131
3132 T heap_oop = oopDesc::load_heap_oop(p);
3133 if (!oopDesc::is_null(heap_oop)) {
3134 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3135
3136 // Now fetch the region containing the object
3137 HeapRegion* hr = _g1h->heap_region_containing(obj);
3138 HeapRegionRemSet* hrrs = hr->rem_set();
3139 // Verify that the strong code root list for this region
3140 // contains the nmethod
3141 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3142 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3143 "from nmethod "PTR_FORMAT" not in strong "
3144 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3145 p, _nm, hr->bottom(), hr->end());
3146 _failures = true;
3147 }
3148 }
3149 }
3150
3151 public:
3152 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3153 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3154
3155 void do_oop(oop* p) { do_oop_work(p); }
3156 void do_oop(narrowOop* p) { do_oop_work(p); }
3157
3158 void set_nmethod(nmethod* nm) { _nm = nm; }
3159 bool failures() { return _failures; }
3160 };
3161
3162 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3163 G1VerifyCodeRootOopClosure* _oop_cl;
3164
3165 public:
3166 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3167 _oop_cl(oop_cl) {}
3168
3169 void do_code_blob(CodeBlob* cb) {
3170 nmethod* nm = cb->as_nmethod_or_null();
3171 if (nm != NULL) {
3172 _oop_cl->set_nmethod(nm);
3173 nm->oops_do(_oop_cl);
3174 }
3175 }
3176 };
3177
3178 class YoungRefCounterClosure : public OopClosure {
3179 G1CollectedHeap* _g1h;
3180 int _count;
3181 public:
3182 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3183 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3184 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3185
3186 int count() { return _count; }
3187 void reset_count() { _count = 0; };
3188 };
3189
3190 class VerifyKlassClosure: public KlassClosure {
3191 YoungRefCounterClosure _young_ref_counter_closure;
3192 OopClosure *_oop_closure;
3193 public:
3194 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3195 void do_klass(Klass* k) {
3196 k->oops_do(_oop_closure);
3197
3198 _young_ref_counter_closure.reset_count();
3199 k->oops_do(&_young_ref_counter_closure);
3200 if (_young_ref_counter_closure.count() > 0) {
3201 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3202 }
3203 }
3204 };
3205
3206 class VerifyLivenessOopClosure: public OopClosure {
3207 G1CollectedHeap* _g1h;
3208 VerifyOption _vo;
3209 public:
3210 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3211 _g1h(g1h), _vo(vo)
3212 { }
3213 void do_oop(narrowOop *p) { do_oop_work(p); }
3214 void do_oop( oop *p) { do_oop_work(p); }
3215
3216 template <class T> void do_oop_work(T *p) {
3217 oop obj = oopDesc::load_decode_heap_oop(p);
3218 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3219 "Dead object referenced by a not dead object");
3220 }
3221 };
3222
3223 class VerifyObjsInRegionClosure: public ObjectClosure {
3224 private:
3225 G1CollectedHeap* _g1h;
3226 size_t _live_bytes;
3227 HeapRegion *_hr;
3228 VerifyOption _vo;
3229 public:
3230 // _vo == UsePrevMarking -> use "prev" marking information,
3231 // _vo == UseNextMarking -> use "next" marking information,
3232 // _vo == UseMarkWord -> use mark word from object header.
3233 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3234 : _live_bytes(0), _hr(hr), _vo(vo) {
3235 _g1h = G1CollectedHeap::heap();
3236 }
3237 void do_object(oop o) {
3238 VerifyLivenessOopClosure isLive(_g1h, _vo);
3239 assert(o != NULL, "Huh?");
3240 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3241 // If the object is alive according to the mark word,
3242 // then verify that the marking information agrees.
3243 // Note we can't verify the contra-positive of the
3244 // above: if the object is dead (according to the mark
3245 // word), it may not be marked, or may have been marked
3246 // but has since became dead, or may have been allocated
3247 // since the last marking.
3248 if (_vo == VerifyOption_G1UseMarkWord) {
3249 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3250 }
3251
3252 o->oop_iterate_no_header(&isLive);
3253 if (!_hr->obj_allocated_since_prev_marking(o)) {
3254 size_t obj_size = o->size(); // Make sure we don't overflow
3255 _live_bytes += (obj_size * HeapWordSize);
3256 }
3257 }
3258 }
3259 size_t live_bytes() { return _live_bytes; }
3260 };
3261
3262 class PrintObjsInRegionClosure : public ObjectClosure {
3263 HeapRegion *_hr;
3264 G1CollectedHeap *_g1;
3265 public:
3266 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3267 _g1 = G1CollectedHeap::heap();
3268 };
3269
3270 void do_object(oop o) {
3271 if (o != NULL) {
3272 HeapWord *start = (HeapWord *) o;
3273 size_t word_sz = o->size();
3274 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3275 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3276 (void*) o, word_sz,
3277 _g1->isMarkedPrev(o),
3278 _g1->isMarkedNext(o),
3279 _hr->obj_allocated_since_prev_marking(o));
3280 HeapWord *end = start + word_sz;
3281 HeapWord *cur;
3282 int *val;
3283 for (cur = start; cur < end; cur++) {
3284 val = (int *) cur;
3285 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3286 }
3287 }
3288 }
3289 };
3290
3291 class VerifyRegionClosure: public HeapRegionClosure {
3292 private:
3293 bool _par;
3294 VerifyOption _vo;
3295 bool _failures;
3296 public:
3297 // _vo == UsePrevMarking -> use "prev" marking information,
3298 // _vo == UseNextMarking -> use "next" marking information,
3299 // _vo == UseMarkWord -> use mark word from object header.
3300 VerifyRegionClosure(bool par, VerifyOption vo)
3301 : _par(par),
3302 _vo(vo),
3303 _failures(false) {}
3304
3305 bool failures() {
3306 return _failures;
3307 }
3308
3309 bool doHeapRegion(HeapRegion* r) {
3310 if (!r->continuesHumongous()) {
3311 bool failures = false;
3312 r->verify(_vo, &failures);
3313 if (failures) {
3314 _failures = true;
3315 } else {
3316 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3317 r->object_iterate(¬_dead_yet_cl);
3318 if (_vo != VerifyOption_G1UseNextMarking) {
3319 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3320 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3321 "max_live_bytes "SIZE_FORMAT" "
3322 "< calculated "SIZE_FORMAT,
3323 r->bottom(), r->end(),
3324 r->max_live_bytes(),
3325 not_dead_yet_cl.live_bytes());
3326 _failures = true;
3327 }
3328 } else {
3329 // When vo == UseNextMarking we cannot currently do a sanity
3330 // check on the live bytes as the calculation has not been
3331 // finalized yet.
3332 }
3333 }
3334 }
3335 return false; // stop the region iteration if we hit a failure
3336 }
3337 };
3338
3339 // This is the task used for parallel verification of the heap regions
3340
3341 class G1ParVerifyTask: public AbstractGangTask {
3342 private:
3343 G1CollectedHeap* _g1h;
3344 VerifyOption _vo;
3345 bool _failures;
3346
3347 public:
3348 // _vo == UsePrevMarking -> use "prev" marking information,
3349 // _vo == UseNextMarking -> use "next" marking information,
3350 // _vo == UseMarkWord -> use mark word from object header.
3351 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3352 AbstractGangTask("Parallel verify task"),
3353 _g1h(g1h),
3354 _vo(vo),
3355 _failures(false) { }
3356
3357 bool failures() {
3358 return _failures;
3359 }
3360
3361 void work(uint worker_id) {
3362 HandleMark hm;
3363 VerifyRegionClosure blk(true, _vo);
3364 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3365 _g1h->workers()->active_workers(),
3366 HeapRegion::ParVerifyClaimValue);
3367 if (blk.failures()) {
3368 _failures = true;
3369 }
3370 }
3371 };
3372
3373 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3374 if (SafepointSynchronize::is_at_safepoint()) {
3375 assert(Thread::current()->is_VM_thread(),
3376 "Expected to be executed serially by the VM thread at this point");
3377
3378 if (!silent) { gclog_or_tty->print("Roots "); }
3379 VerifyRootsClosure rootsCl(vo);
3380 VerifyKlassClosure klassCl(this, &rootsCl);
3381
3382 // We apply the relevant closures to all the oops in the
3383 // system dictionary, class loader data graph and the string table.
3384 // Don't verify the code cache here, since it's verified below.
3385 const int so = SO_AllClasses | SO_Strings;
3386
3387 // Need cleared claim bits for the strong roots processing
3388 ClassLoaderDataGraph::clear_claimed_marks();
3389
3390 process_strong_roots(true, // activate StrongRootsScope
3391 ScanningOption(so), // roots scanning options
3392 &rootsCl,
3393 &klassCl
3394 );
3395
3396 // Verify the nmethods in the code cache.
3397 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3398 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3399 CodeCache::blobs_do(&blobsCl);
3400
3401 bool failures = rootsCl.failures() || codeRootsCl.failures();
3402
3403 if (vo != VerifyOption_G1UseMarkWord) {
3404 // If we're verifying during a full GC then the region sets
3405 // will have been torn down at the start of the GC. Therefore
3406 // verifying the region sets will fail. So we only verify
3407 // the region sets when not in a full GC.
3408 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3409 verify_region_sets();
3410 }
3411
3412 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3413 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3414 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3415 "sanity check");
3416
3417 G1ParVerifyTask task(this, vo);
3418 assert(UseDynamicNumberOfGCThreads ||
3419 workers()->active_workers() == workers()->total_workers(),
3420 "If not dynamic should be using all the workers");
3421 int n_workers = workers()->active_workers();
3422 set_par_threads(n_workers);
3423 workers()->run_task(&task);
3424 set_par_threads(0);
3425 if (task.failures()) {
3426 failures = true;
3427 }
3428
3429 // Checks that the expected amount of parallel work was done.
3430 // The implication is that n_workers is > 0.
3431 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3432 "sanity check");
3433
3434 reset_heap_region_claim_values();
3435
3436 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3437 "sanity check");
3438 } else {
3439 VerifyRegionClosure blk(false, vo);
3440 heap_region_iterate(&blk);
3441 if (blk.failures()) {
3442 failures = true;
3443 }
3444 }
3445 if (!silent) gclog_or_tty->print("RemSet ");
3446 rem_set()->verify();
3447
3448 if (G1StringDedup::is_enabled()) {
3449 if (!silent) gclog_or_tty->print("StrDedup ");
3450 G1StringDedup::verify();
3451 }
3452
3453 if (failures) {
3454 gclog_or_tty->print_cr("Heap:");
3455 // It helps to have the per-region information in the output to
3456 // help us track down what went wrong. This is why we call
3457 // print_extended_on() instead of print_on().
3458 print_extended_on(gclog_or_tty);
3459 gclog_or_tty->print_cr("");
3460 #ifndef PRODUCT
3461 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3462 concurrent_mark()->print_reachable("at-verification-failure",
3463 vo, false /* all */);
3464 }
3465 #endif
3466 gclog_or_tty->flush();
3467 }
3468 guarantee(!failures, "there should not have been any failures");
3469 } else {
3470 if (!silent) {
3471 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3472 if (G1StringDedup::is_enabled()) {
3473 gclog_or_tty->print(", StrDedup");
3474 }
3475 gclog_or_tty->print(") ");
3476 }
3477 }
3478 }
3479
3480 void G1CollectedHeap::verify(bool silent) {
3481 verify(silent, VerifyOption_G1UsePrevMarking);
3482 }
3483
3484 double G1CollectedHeap::verify(bool guard, const char* msg) {
3485 double verify_time_ms = 0.0;
3486
3487 if (guard && total_collections() >= VerifyGCStartAt) {
3488 double verify_start = os::elapsedTime();
3489 HandleMark hm; // Discard invalid handles created during verification
3490 prepare_for_verify();
3491 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3492 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3493 }
3494
3495 return verify_time_ms;
3496 }
3497
3498 void G1CollectedHeap::verify_before_gc() {
3499 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3500 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3501 }
3502
3503 void G1CollectedHeap::verify_after_gc() {
3504 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3505 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3506 }
3507
3508 class PrintRegionClosure: public HeapRegionClosure {
3509 outputStream* _st;
3510 public:
3511 PrintRegionClosure(outputStream* st) : _st(st) {}
3512 bool doHeapRegion(HeapRegion* r) {
3513 r->print_on(_st);
3514 return false;
3515 }
3516 };
3517
3518 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3519 const HeapRegion* hr,
3520 const VerifyOption vo) const {
3521 switch (vo) {
3522 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3523 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3524 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3525 default: ShouldNotReachHere();
3526 }
3527 return false; // keep some compilers happy
3528 }
3529
3530 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3531 const VerifyOption vo) const {
3532 switch (vo) {
3533 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3534 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3535 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3536 default: ShouldNotReachHere();
3537 }
3538 return false; // keep some compilers happy
3539 }
3540
3541 void G1CollectedHeap::print_on(outputStream* st) const {
3542 st->print(" %-20s", "garbage-first heap");
3543 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3544 capacity()/K, used_unlocked()/K);
3545 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3546 _g1_storage.low_boundary(),
3547 _g1_storage.high(),
3548 _g1_storage.high_boundary());
3549 st->cr();
3550 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3551 uint young_regions = _young_list->length();
3552 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3553 (size_t) young_regions * HeapRegion::GrainBytes / K);
3554 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3555 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3556 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3557 st->cr();
3558 MetaspaceAux::print_on(st);
3559 }
3560
3561 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3562 print_on(st);
3563
3564 // Print the per-region information.
3565 st->cr();
3566 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3567 "HS=humongous(starts), HC=humongous(continues), "
3568 "CS=collection set, F=free, TS=gc time stamp, "
3569 "PTAMS=previous top-at-mark-start, "
3570 "NTAMS=next top-at-mark-start)");
3571 PrintRegionClosure blk(st);
3572 heap_region_iterate(&blk);
3573 }
3574
3575 void G1CollectedHeap::print_on_error(outputStream* st) const {
3576 this->CollectedHeap::print_on_error(st);
3577
3578 if (_cm != NULL) {
3579 st->cr();
3580 _cm->print_on_error(st);
3581 }
3582 }
3583
3584 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3585 if (G1CollectedHeap::use_parallel_gc_threads()) {
3586 workers()->print_worker_threads_on(st);
3587 }
3588 _cmThread->print_on(st);
3589 st->cr();
3590 _cm->print_worker_threads_on(st);
3591 _cg1r->print_worker_threads_on(st);
3592 if (G1StringDedup::is_enabled()) {
3593 G1StringDedup::print_worker_threads_on(st);
3594 }
3595 }
3596
3597 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3598 if (G1CollectedHeap::use_parallel_gc_threads()) {
3599 workers()->threads_do(tc);
3600 }
3601 tc->do_thread(_cmThread);
3602 _cg1r->threads_do(tc);
3603 if (G1StringDedup::is_enabled()) {
3604 G1StringDedup::threads_do(tc);
3605 }
3606 }
3607
3608 void G1CollectedHeap::print_tracing_info() const {
3609 // We'll overload this to mean "trace GC pause statistics."
3610 if (TraceGen0Time || TraceGen1Time) {
3611 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3612 // to that.
3613 g1_policy()->print_tracing_info();
3614 }
3615 if (G1SummarizeRSetStats) {
3616 g1_rem_set()->print_summary_info();
3617 }
3618 if (G1SummarizeConcMark) {
3619 concurrent_mark()->print_summary_info();
3620 }
3621 g1_policy()->print_yg_surv_rate_info();
3622 SpecializationStats::print();
3623 }
3624
3625 #ifndef PRODUCT
3626 // Helpful for debugging RSet issues.
3627
3628 class PrintRSetsClosure : public HeapRegionClosure {
3629 private:
3630 const char* _msg;
3631 size_t _occupied_sum;
3632
3633 public:
3634 bool doHeapRegion(HeapRegion* r) {
3635 HeapRegionRemSet* hrrs = r->rem_set();
3636 size_t occupied = hrrs->occupied();
3637 _occupied_sum += occupied;
3638
3639 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3640 HR_FORMAT_PARAMS(r));
3641 if (occupied == 0) {
3642 gclog_or_tty->print_cr(" RSet is empty");
3643 } else {
3644 hrrs->print();
3645 }
3646 gclog_or_tty->print_cr("----------");
3647 return false;
3648 }
3649
3650 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3651 gclog_or_tty->cr();
3652 gclog_or_tty->print_cr("========================================");
3653 gclog_or_tty->print_cr(msg);
3654 gclog_or_tty->cr();
3655 }
3656
3657 ~PrintRSetsClosure() {
3658 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3659 gclog_or_tty->print_cr("========================================");
3660 gclog_or_tty->cr();
3661 }
3662 };
3663
3664 void G1CollectedHeap::print_cset_rsets() {
3665 PrintRSetsClosure cl("Printing CSet RSets");
3666 collection_set_iterate(&cl);
3667 }
3668
3669 void G1CollectedHeap::print_all_rsets() {
3670 PrintRSetsClosure cl("Printing All RSets");;
3671 heap_region_iterate(&cl);
3672 }
3673 #endif // PRODUCT
3674
3675 G1CollectedHeap* G1CollectedHeap::heap() {
3676 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3677 "not a garbage-first heap");
3678 return _g1h;
3679 }
3680
3681 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3682 // always_do_update_barrier = false;
3683 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3684 // Fill TLAB's and such
3685 accumulate_statistics_all_tlabs();
3686 ensure_parsability(true);
3687
3688 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3689 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3690 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3691 }
3692 }
3693
3694 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3695
3696 if (G1SummarizeRSetStats &&
3697 (G1SummarizeRSetStatsPeriod > 0) &&
3698 // we are at the end of the GC. Total collections has already been increased.
3699 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3700 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3701 }
3702
3703 // FIXME: what is this about?
3704 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3705 // is set.
3706 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3707 "derived pointer present"));
3708 // always_do_update_barrier = true;
3709
3710 resize_all_tlabs();
3711
3712 // We have just completed a GC. Update the soft reference
3713 // policy with the new heap occupancy
3714 Universe::update_heap_info_at_gc();
3715 }
3716
3717 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3718 unsigned int gc_count_before,
3719 bool* succeeded,
3720 GCCause::Cause gc_cause) {
3721 assert_heap_not_locked_and_not_at_safepoint();
3722 g1_policy()->record_stop_world_start();
3723 VM_G1IncCollectionPause op(gc_count_before,
3724 word_size,
3725 false, /* should_initiate_conc_mark */
3726 g1_policy()->max_pause_time_ms(),
3727 gc_cause);
3728 VMThread::execute(&op);
3729
3730 HeapWord* result = op.result();
3731 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3732 assert(result == NULL || ret_succeeded,
3733 "the result should be NULL if the VM did not succeed");
3734 *succeeded = ret_succeeded;
3735
3736 assert_heap_not_locked();
3737 return result;
3738 }
3739
3740 void
3741 G1CollectedHeap::doConcurrentMark() {
3742 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3743 if (!_cmThread->in_progress()) {
3744 _cmThread->set_started();
3745 CGC_lock->notify();
3746 }
3747 }
3748
3749 size_t G1CollectedHeap::pending_card_num() {
3750 size_t extra_cards = 0;
3751 JavaThread *curr = Threads::first();
3752 while (curr != NULL) {
3753 DirtyCardQueue& dcq = curr->dirty_card_queue();
3754 extra_cards += dcq.size();
3755 curr = curr->next();
3756 }
3757 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3758 size_t buffer_size = dcqs.buffer_size();
3759 size_t buffer_num = dcqs.completed_buffers_num();
3760
3761 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3762 // in bytes - not the number of 'entries'. We need to convert
3763 // into a number of cards.
3764 return (buffer_size * buffer_num + extra_cards) / oopSize;
3765 }
3766
3767 size_t G1CollectedHeap::cards_scanned() {
3768 return g1_rem_set()->cardsScanned();
3769 }
3770
3771 void
3772 G1CollectedHeap::setup_surviving_young_words() {
3773 assert(_surviving_young_words == NULL, "pre-condition");
3774 uint array_length = g1_policy()->young_cset_region_length();
3775 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3776 if (_surviving_young_words == NULL) {
3777 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3778 "Not enough space for young surv words summary.");
3779 }
3780 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3781 #ifdef ASSERT
3782 for (uint i = 0; i < array_length; ++i) {
3783 assert( _surviving_young_words[i] == 0, "memset above" );
3784 }
3785 #endif // !ASSERT
3786 }
3787
3788 void
3789 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3790 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3791 uint array_length = g1_policy()->young_cset_region_length();
3792 for (uint i = 0; i < array_length; ++i) {
3793 _surviving_young_words[i] += surv_young_words[i];
3794 }
3795 }
3796
3797 void
3798 G1CollectedHeap::cleanup_surviving_young_words() {
3799 guarantee( _surviving_young_words != NULL, "pre-condition" );
3800 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3801 _surviving_young_words = NULL;
3802 }
3803
3804 #ifdef ASSERT
3805 class VerifyCSetClosure: public HeapRegionClosure {
3806 public:
3807 bool doHeapRegion(HeapRegion* hr) {
3808 // Here we check that the CSet region's RSet is ready for parallel
3809 // iteration. The fields that we'll verify are only manipulated
3810 // when the region is part of a CSet and is collected. Afterwards,
3811 // we reset these fields when we clear the region's RSet (when the
3812 // region is freed) so they are ready when the region is
3813 // re-allocated. The only exception to this is if there's an
3814 // evacuation failure and instead of freeing the region we leave
3815 // it in the heap. In that case, we reset these fields during
3816 // evacuation failure handling.
3817 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3818
3819 // Here's a good place to add any other checks we'd like to
3820 // perform on CSet regions.
3821 return false;
3822 }
3823 };
3824 #endif // ASSERT
3825
3826 #if TASKQUEUE_STATS
3827 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3828 st->print_raw_cr("GC Task Stats");
3829 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3830 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3831 }
3832
3833 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3834 print_taskqueue_stats_hdr(st);
3835
3836 TaskQueueStats totals;
3837 const int n = workers() != NULL ? workers()->total_workers() : 1;
3838 for (int i = 0; i < n; ++i) {
3839 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3840 totals += task_queue(i)->stats;
3841 }
3842 st->print_raw("tot "); totals.print(st); st->cr();
3843
3844 DEBUG_ONLY(totals.verify());
3845 }
3846
3847 void G1CollectedHeap::reset_taskqueue_stats() {
3848 const int n = workers() != NULL ? workers()->total_workers() : 1;
3849 for (int i = 0; i < n; ++i) {
3850 task_queue(i)->stats.reset();
3851 }
3852 }
3853 #endif // TASKQUEUE_STATS
3854
3855 void G1CollectedHeap::log_gc_header() {
3856 if (!G1Log::fine()) {
3857 return;
3858 }
3859
3860 gclog_or_tty->date_stamp(PrintGCDateStamps);
3861 gclog_or_tty->stamp(PrintGCTimeStamps);
3862
3863 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3864 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3865 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3866
3867 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3868 }
3869
3870 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3871 if (!G1Log::fine()) {
3872 return;
3873 }
3874
3875 if (G1Log::finer()) {
3876 if (evacuation_failed()) {
3877 gclog_or_tty->print(" (to-space exhausted)");
3878 }
3879 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3880 g1_policy()->phase_times()->note_gc_end();
3881 g1_policy()->phase_times()->print(pause_time_sec);
3882 g1_policy()->print_detailed_heap_transition();
3883 } else {
3884 if (evacuation_failed()) {
3885 gclog_or_tty->print("--");
3886 }
3887 g1_policy()->print_heap_transition();
3888 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3889 }
3890 gclog_or_tty->flush();
3891 }
3892
3893 bool
3894 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3895 assert_at_safepoint(true /* should_be_vm_thread */);
3896 guarantee(!is_gc_active(), "collection is not reentrant");
3897
3898 if (GC_locker::check_active_before_gc()) {
3899 return false;
3900 }
3901
3902 _gc_timer_stw->register_gc_start();
3903
3904 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3905
3906 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3907 ResourceMark rm;
3908
3909 print_heap_before_gc();
3910 trace_heap_before_gc(_gc_tracer_stw);
3911
3912 verify_region_sets_optional();
3913 verify_dirty_young_regions();
3914
3915 // This call will decide whether this pause is an initial-mark
3916 // pause. If it is, during_initial_mark_pause() will return true
3917 // for the duration of this pause.
3918 g1_policy()->decide_on_conc_mark_initiation();
3919
3920 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3921 assert(!g1_policy()->during_initial_mark_pause() ||
3922 g1_policy()->gcs_are_young(), "sanity");
3923
3924 // We also do not allow mixed GCs during marking.
3925 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3926
3927 // Record whether this pause is an initial mark. When the current
3928 // thread has completed its logging output and it's safe to signal
3929 // the CM thread, the flag's value in the policy has been reset.
3930 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3931
3932 // Inner scope for scope based logging, timers, and stats collection
3933 {
3934 EvacuationInfo evacuation_info;
3935
3936 if (g1_policy()->during_initial_mark_pause()) {
3937 // We are about to start a marking cycle, so we increment the
3938 // full collection counter.
3939 increment_old_marking_cycles_started();
3940 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3941 }
3942
3943 _gc_tracer_stw->report_yc_type(yc_type());
3944
3945 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3946
3947 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3948 workers()->active_workers() : 1);
3949 double pause_start_sec = os::elapsedTime();
3950 g1_policy()->phase_times()->note_gc_start(active_workers);
3951 log_gc_header();
3952
3953 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3954 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3955
3956 // If the secondary_free_list is not empty, append it to the
3957 // free_list. No need to wait for the cleanup operation to finish;
3958 // the region allocation code will check the secondary_free_list
3959 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3960 // set, skip this step so that the region allocation code has to
3961 // get entries from the secondary_free_list.
3962 if (!G1StressConcRegionFreeing) {
3963 append_secondary_free_list_if_not_empty_with_lock();
3964 }
3965
3966 assert(check_young_list_well_formed(), "young list should be well formed");
3967 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3968 "sanity check");
3969
3970 // Don't dynamically change the number of GC threads this early. A value of
3971 // 0 is used to indicate serial work. When parallel work is done,
3972 // it will be set.
3973
3974 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3975 IsGCActiveMark x;
3976
3977 gc_prologue(false);
3978 increment_total_collections(false /* full gc */);
3979 increment_gc_time_stamp();
3980
3981 verify_before_gc();
3982
3983 COMPILER2_PRESENT(DerivedPointerTable::clear());
3984
3985 // Please see comment in g1CollectedHeap.hpp and
3986 // G1CollectedHeap::ref_processing_init() to see how
3987 // reference processing currently works in G1.
3988
3989 // Enable discovery in the STW reference processor
3990 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3991 true /*verify_no_refs*/);
3992
3993 {
3994 // We want to temporarily turn off discovery by the
3995 // CM ref processor, if necessary, and turn it back on
3996 // on again later if we do. Using a scoped
3997 // NoRefDiscovery object will do this.
3998 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3999
4000 // Forget the current alloc region (we might even choose it to be part
4001 // of the collection set!).
4002 release_mutator_alloc_region();
4003
4004 // We should call this after we retire the mutator alloc
4005 // region(s) so that all the ALLOC / RETIRE events are generated
4006 // before the start GC event.
4007 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4008
4009 // This timing is only used by the ergonomics to handle our pause target.
4010 // It is unclear why this should not include the full pause. We will
4011 // investigate this in CR 7178365.
4012 //
4013 // Preserving the old comment here if that helps the investigation:
4014 //
4015 // The elapsed time induced by the start time below deliberately elides
4016 // the possible verification above.
4017 double sample_start_time_sec = os::elapsedTime();
4018
4019 #if YOUNG_LIST_VERBOSE
4020 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4021 _young_list->print();
4022 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4023 #endif // YOUNG_LIST_VERBOSE
4024
4025 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4026
4027 double scan_wait_start = os::elapsedTime();
4028 // We have to wait until the CM threads finish scanning the
4029 // root regions as it's the only way to ensure that all the
4030 // objects on them have been correctly scanned before we start
4031 // moving them during the GC.
4032 bool waited = _cm->root_regions()->wait_until_scan_finished();
4033 double wait_time_ms = 0.0;
4034 if (waited) {
4035 double scan_wait_end = os::elapsedTime();
4036 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4037 }
4038 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4039
4040 #if YOUNG_LIST_VERBOSE
4041 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4042 _young_list->print();
4043 #endif // YOUNG_LIST_VERBOSE
4044
4045 if (g1_policy()->during_initial_mark_pause()) {
4046 concurrent_mark()->checkpointRootsInitialPre();
4047 }
4048
4049 #if YOUNG_LIST_VERBOSE
4050 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4051 _young_list->print();
4052 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4053 #endif // YOUNG_LIST_VERBOSE
4054
4055 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4056
4057 _cm->note_start_of_gc();
4058 // We should not verify the per-thread SATB buffers given that
4059 // we have not filtered them yet (we'll do so during the
4060 // GC). We also call this after finalize_cset() to
4061 // ensure that the CSet has been finalized.
4062 _cm->verify_no_cset_oops(true /* verify_stacks */,
4063 true /* verify_enqueued_buffers */,
4064 false /* verify_thread_buffers */,
4065 true /* verify_fingers */);
4066
4067 if (_hr_printer.is_active()) {
4068 HeapRegion* hr = g1_policy()->collection_set();
4069 while (hr != NULL) {
4070 G1HRPrinter::RegionType type;
4071 if (!hr->is_young()) {
4072 type = G1HRPrinter::Old;
4073 } else if (hr->is_survivor()) {
4074 type = G1HRPrinter::Survivor;
4075 } else {
4076 type = G1HRPrinter::Eden;
4077 }
4078 _hr_printer.cset(hr);
4079 hr = hr->next_in_collection_set();
4080 }
4081 }
4082
4083 #ifdef ASSERT
4084 VerifyCSetClosure cl;
4085 collection_set_iterate(&cl);
4086 #endif // ASSERT
4087
4088 setup_surviving_young_words();
4089
4090 // Initialize the GC alloc regions.
4091 init_gc_alloc_regions(evacuation_info);
4092
4093 // Actually do the work...
4094 evacuate_collection_set(evacuation_info);
4095
4096 // We do this to mainly verify the per-thread SATB buffers
4097 // (which have been filtered by now) since we didn't verify
4098 // them earlier. No point in re-checking the stacks / enqueued
4099 // buffers given that the CSet has not changed since last time
4100 // we checked.
4101 _cm->verify_no_cset_oops(false /* verify_stacks */,
4102 false /* verify_enqueued_buffers */,
4103 true /* verify_thread_buffers */,
4104 true /* verify_fingers */);
4105
4106 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4107 g1_policy()->clear_collection_set();
4108
4109 cleanup_surviving_young_words();
4110
4111 // Start a new incremental collection set for the next pause.
4112 g1_policy()->start_incremental_cset_building();
4113
4114 // Clear the _cset_fast_test bitmap in anticipation of adding
4115 // regions to the incremental collection set for the next
4116 // evacuation pause.
4117 clear_cset_fast_test();
4118
4119 _young_list->reset_sampled_info();
4120
4121 // Don't check the whole heap at this point as the
4122 // GC alloc regions from this pause have been tagged
4123 // as survivors and moved on to the survivor list.
4124 // Survivor regions will fail the !is_young() check.
4125 assert(check_young_list_empty(false /* check_heap */),
4126 "young list should be empty");
4127
4128 #if YOUNG_LIST_VERBOSE
4129 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4130 _young_list->print();
4131 #endif // YOUNG_LIST_VERBOSE
4132
4133 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4134 _young_list->first_survivor_region(),
4135 _young_list->last_survivor_region());
4136
4137 _young_list->reset_auxilary_lists();
4138
4139 if (evacuation_failed()) {
4140 _summary_bytes_used = recalculate_used();
4141 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4142 for (uint i = 0; i < n_queues; i++) {
4143 if (_evacuation_failed_info_array[i].has_failed()) {
4144 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4145 }
4146 }
4147 } else {
4148 // The "used" of the the collection set have already been subtracted
4149 // when they were freed. Add in the bytes evacuated.
4150 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4151 }
4152
4153 if (g1_policy()->during_initial_mark_pause()) {
4154 // We have to do this before we notify the CM threads that
4155 // they can start working to make sure that all the
4156 // appropriate initialization is done on the CM object.
4157 concurrent_mark()->checkpointRootsInitialPost();
4158 set_marking_started();
4159 // Note that we don't actually trigger the CM thread at
4160 // this point. We do that later when we're sure that
4161 // the current thread has completed its logging output.
4162 }
4163
4164 allocate_dummy_regions();
4165
4166 #if YOUNG_LIST_VERBOSE
4167 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4168 _young_list->print();
4169 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4170 #endif // YOUNG_LIST_VERBOSE
4171
4172 init_mutator_alloc_region();
4173
4174 {
4175 size_t expand_bytes = g1_policy()->expansion_amount();
4176 if (expand_bytes > 0) {
4177 size_t bytes_before = capacity();
4178 // No need for an ergo verbose message here,
4179 // expansion_amount() does this when it returns a value > 0.
4180 if (!expand(expand_bytes)) {
4181 // We failed to expand the heap so let's verify that
4182 // committed/uncommitted amount match the backing store
4183 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4184 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4185 }
4186 }
4187 }
4188
4189 // We redo the verification but now wrt to the new CSet which
4190 // has just got initialized after the previous CSet was freed.
4191 _cm->verify_no_cset_oops(true /* verify_stacks */,
4192 true /* verify_enqueued_buffers */,
4193 true /* verify_thread_buffers */,
4194 true /* verify_fingers */);
4195 _cm->note_end_of_gc();
4196
4197 // This timing is only used by the ergonomics to handle our pause target.
4198 // It is unclear why this should not include the full pause. We will
4199 // investigate this in CR 7178365.
4200 double sample_end_time_sec = os::elapsedTime();
4201 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4202 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4203
4204 MemoryService::track_memory_usage();
4205
4206 // In prepare_for_verify() below we'll need to scan the deferred
4207 // update buffers to bring the RSets up-to-date if
4208 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4209 // the update buffers we'll probably need to scan cards on the
4210 // regions we just allocated to (i.e., the GC alloc
4211 // regions). However, during the last GC we called
4212 // set_saved_mark() on all the GC alloc regions, so card
4213 // scanning might skip the [saved_mark_word()...top()] area of
4214 // those regions (i.e., the area we allocated objects into
4215 // during the last GC). But it shouldn't. Given that
4216 // saved_mark_word() is conditional on whether the GC time stamp
4217 // on the region is current or not, by incrementing the GC time
4218 // stamp here we invalidate all the GC time stamps on all the
4219 // regions and saved_mark_word() will simply return top() for
4220 // all the regions. This is a nicer way of ensuring this rather
4221 // than iterating over the regions and fixing them. In fact, the
4222 // GC time stamp increment here also ensures that
4223 // saved_mark_word() will return top() between pauses, i.e.,
4224 // during concurrent refinement. So we don't need the
4225 // is_gc_active() check to decided which top to use when
4226 // scanning cards (see CR 7039627).
4227 increment_gc_time_stamp();
4228
4229 verify_after_gc();
4230
4231 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4232 ref_processor_stw()->verify_no_references_recorded();
4233
4234 // CM reference discovery will be re-enabled if necessary.
4235 }
4236
4237 // We should do this after we potentially expand the heap so
4238 // that all the COMMIT events are generated before the end GC
4239 // event, and after we retire the GC alloc regions so that all
4240 // RETIRE events are generated before the end GC event.
4241 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4242
4243 if (mark_in_progress()) {
4244 concurrent_mark()->update_g1_committed();
4245 }
4246
4247 #ifdef TRACESPINNING
4248 ParallelTaskTerminator::print_termination_counts();
4249 #endif
4250
4251 gc_epilogue(false);
4252 }
4253
4254 // Print the remainder of the GC log output.
4255 log_gc_footer(os::elapsedTime() - pause_start_sec);
4256
4257 // It is not yet to safe to tell the concurrent mark to
4258 // start as we have some optional output below. We don't want the
4259 // output from the concurrent mark thread interfering with this
4260 // logging output either.
4261
4262 _hrs.verify_optional();
4263 verify_region_sets_optional();
4264
4265 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4266 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4267
4268 print_heap_after_gc();
4269 trace_heap_after_gc(_gc_tracer_stw);
4270
4271 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4272 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4273 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4274 // before any GC notifications are raised.
4275 g1mm()->update_sizes();
4276
4277 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4278 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4279 _gc_timer_stw->register_gc_end();
4280 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4281 }
4282 // It should now be safe to tell the concurrent mark thread to start
4283 // without its logging output interfering with the logging output
4284 // that came from the pause.
4285
4286 if (should_start_conc_mark) {
4287 // CAUTION: after the doConcurrentMark() call below,
4288 // the concurrent marking thread(s) could be running
4289 // concurrently with us. Make sure that anything after
4290 // this point does not assume that we are the only GC thread
4291 // running. Note: of course, the actual marking work will
4292 // not start until the safepoint itself is released in
4293 // ConcurrentGCThread::safepoint_desynchronize().
4294 doConcurrentMark();
4295 }
4296
4297 return true;
4298 }
4299
4300 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4301 {
4302 size_t gclab_word_size;
4303 switch (purpose) {
4304 case GCAllocForSurvived:
4305 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4306 break;
4307 case GCAllocForTenured:
4308 gclab_word_size = _old_plab_stats.desired_plab_sz();
4309 break;
4310 default:
4311 assert(false, "unknown GCAllocPurpose");
4312 gclab_word_size = _old_plab_stats.desired_plab_sz();
4313 break;
4314 }
4315
4316 // Prevent humongous PLAB sizes for two reasons:
4317 // * PLABs are allocated using a similar paths as oops, but should
4318 // never be in a humongous region
4319 // * Allowing humongous PLABs needlessly churns the region free lists
4320 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4321 }
4322
4323 void G1CollectedHeap::init_mutator_alloc_region() {
4324 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4325 _mutator_alloc_region.init();
4326 }
4327
4328 void G1CollectedHeap::release_mutator_alloc_region() {
4329 _mutator_alloc_region.release();
4330 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4331 }
4332
4333 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4334 assert_at_safepoint(true /* should_be_vm_thread */);
4335
4336 _survivor_gc_alloc_region.init();
4337 _old_gc_alloc_region.init();
4338 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4339 _retained_old_gc_alloc_region = NULL;
4340
4341 // We will discard the current GC alloc region if:
4342 // a) it's in the collection set (it can happen!),
4343 // b) it's already full (no point in using it),
4344 // c) it's empty (this means that it was emptied during
4345 // a cleanup and it should be on the free list now), or
4346 // d) it's humongous (this means that it was emptied
4347 // during a cleanup and was added to the free list, but
4348 // has been subsequently used to allocate a humongous
4349 // object that may be less than the region size).
4350 if (retained_region != NULL &&
4351 !retained_region->in_collection_set() &&
4352 !(retained_region->top() == retained_region->end()) &&
4353 !retained_region->is_empty() &&
4354 !retained_region->isHumongous()) {
4355 retained_region->set_saved_mark();
4356 // The retained region was added to the old region set when it was
4357 // retired. We have to remove it now, since we don't allow regions
4358 // we allocate to in the region sets. We'll re-add it later, when
4359 // it's retired again.
4360 _old_set.remove(retained_region);
4361 bool during_im = g1_policy()->during_initial_mark_pause();
4362 retained_region->note_start_of_copying(during_im);
4363 _old_gc_alloc_region.set(retained_region);
4364 _hr_printer.reuse(retained_region);
4365 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4366 }
4367 }
4368
4369 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4370 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4371 _old_gc_alloc_region.count());
4372 _survivor_gc_alloc_region.release();
4373 // If we have an old GC alloc region to release, we'll save it in
4374 // _retained_old_gc_alloc_region. If we don't
4375 // _retained_old_gc_alloc_region will become NULL. This is what we
4376 // want either way so no reason to check explicitly for either
4377 // condition.
4378 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4379
4380 if (ResizePLAB) {
4381 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4382 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4383 }
4384 }
4385
4386 void G1CollectedHeap::abandon_gc_alloc_regions() {
4387 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4388 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4389 _retained_old_gc_alloc_region = NULL;
4390 }
4391
4392 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4393 _drain_in_progress = false;
4394 set_evac_failure_closure(cl);
4395 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4396 }
4397
4398 void G1CollectedHeap::finalize_for_evac_failure() {
4399 assert(_evac_failure_scan_stack != NULL &&
4400 _evac_failure_scan_stack->length() == 0,
4401 "Postcondition");
4402 assert(!_drain_in_progress, "Postcondition");
4403 delete _evac_failure_scan_stack;
4404 _evac_failure_scan_stack = NULL;
4405 }
4406
4407 void G1CollectedHeap::remove_self_forwarding_pointers() {
4408 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4409
4410 double remove_self_forwards_start = os::elapsedTime();
4411
4412 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4413
4414 if (G1CollectedHeap::use_parallel_gc_threads()) {
4415 set_par_threads();
4416 workers()->run_task(&rsfp_task);
4417 set_par_threads(0);
4418 } else {
4419 rsfp_task.work(0);
4420 }
4421
4422 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4423
4424 // Reset the claim values in the regions in the collection set.
4425 reset_cset_heap_region_claim_values();
4426
4427 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4428
4429 // Now restore saved marks, if any.
4430 assert(_objs_with_preserved_marks.size() ==
4431 _preserved_marks_of_objs.size(), "Both or none.");
4432 while (!_objs_with_preserved_marks.is_empty()) {
4433 oop obj = _objs_with_preserved_marks.pop();
4434 markOop m = _preserved_marks_of_objs.pop();
4435 obj->set_mark(m);
4436 }
4437 _objs_with_preserved_marks.clear(true);
4438 _preserved_marks_of_objs.clear(true);
4439
4440 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4441 }
4442
4443 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4444 _evac_failure_scan_stack->push(obj);
4445 }
4446
4447 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4448 assert(_evac_failure_scan_stack != NULL, "precondition");
4449
4450 while (_evac_failure_scan_stack->length() > 0) {
4451 oop obj = _evac_failure_scan_stack->pop();
4452 _evac_failure_closure->set_region(heap_region_containing(obj));
4453 obj->oop_iterate_backwards(_evac_failure_closure);
4454 }
4455 }
4456
4457 oop
4458 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4459 oop old) {
4460 assert(obj_in_cs(old),
4461 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4462 (HeapWord*) old));
4463 markOop m = old->mark();
4464 oop forward_ptr = old->forward_to_atomic(old);
4465 if (forward_ptr == NULL) {
4466 // Forward-to-self succeeded.
4467 assert(_par_scan_state != NULL, "par scan state");
4468 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4469 uint queue_num = _par_scan_state->queue_num();
4470
4471 _evacuation_failed = true;
4472 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4473 if (_evac_failure_closure != cl) {
4474 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4475 assert(!_drain_in_progress,
4476 "Should only be true while someone holds the lock.");
4477 // Set the global evac-failure closure to the current thread's.
4478 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4479 set_evac_failure_closure(cl);
4480 // Now do the common part.
4481 handle_evacuation_failure_common(old, m);
4482 // Reset to NULL.
4483 set_evac_failure_closure(NULL);
4484 } else {
4485 // The lock is already held, and this is recursive.
4486 assert(_drain_in_progress, "This should only be the recursive case.");
4487 handle_evacuation_failure_common(old, m);
4488 }
4489 return old;
4490 } else {
4491 // Forward-to-self failed. Either someone else managed to allocate
4492 // space for this object (old != forward_ptr) or they beat us in
4493 // self-forwarding it (old == forward_ptr).
4494 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4495 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4496 "should not be in the CSet",
4497 (HeapWord*) old, (HeapWord*) forward_ptr));
4498 return forward_ptr;
4499 }
4500 }
4501
4502 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4503 preserve_mark_if_necessary(old, m);
4504
4505 HeapRegion* r = heap_region_containing(old);
4506 if (!r->evacuation_failed()) {
4507 r->set_evacuation_failed(true);
4508 _hr_printer.evac_failure(r);
4509 }
4510
4511 push_on_evac_failure_scan_stack(old);
4512
4513 if (!_drain_in_progress) {
4514 // prevent recursion in copy_to_survivor_space()
4515 _drain_in_progress = true;
4516 drain_evac_failure_scan_stack();
4517 _drain_in_progress = false;
4518 }
4519 }
4520
4521 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4522 assert(evacuation_failed(), "Oversaving!");
4523 // We want to call the "for_promotion_failure" version only in the
4524 // case of a promotion failure.
4525 if (m->must_be_preserved_for_promotion_failure(obj)) {
4526 _objs_with_preserved_marks.push(obj);
4527 _preserved_marks_of_objs.push(m);
4528 }
4529 }
4530
4531 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4532 size_t word_size) {
4533 if (purpose == GCAllocForSurvived) {
4534 HeapWord* result = survivor_attempt_allocation(word_size);
4535 if (result != NULL) {
4536 return result;
4537 } else {
4538 // Let's try to allocate in the old gen in case we can fit the
4539 // object there.
4540 return old_attempt_allocation(word_size);
4541 }
4542 } else {
4543 assert(purpose == GCAllocForTenured, "sanity");
4544 HeapWord* result = old_attempt_allocation(word_size);
4545 if (result != NULL) {
4546 return result;
4547 } else {
4548 // Let's try to allocate in the survivors in case we can fit the
4549 // object there.
4550 return survivor_attempt_allocation(word_size);
4551 }
4552 }
4553
4554 ShouldNotReachHere();
4555 // Trying to keep some compilers happy.
4556 return NULL;
4557 }
4558
4559 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4560 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4561
4562 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4563 : _g1h(g1h),
4564 _refs(g1h->task_queue(queue_num)),
4565 _dcq(&g1h->dirty_card_queue_set()),
4566 _ct_bs(g1h->g1_barrier_set()),
4567 _g1_rem(g1h->g1_rem_set()),
4568 _hash_seed(17), _queue_num(queue_num),
4569 _term_attempts(0),
4570 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4571 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4572 _age_table(false), _scanner(g1h, this, rp),
4573 _strong_roots_time(0), _term_time(0),
4574 _alloc_buffer_waste(0), _undo_waste(0) {
4575 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4576 // we "sacrifice" entry 0 to keep track of surviving bytes for
4577 // non-young regions (where the age is -1)
4578 // We also add a few elements at the beginning and at the end in
4579 // an attempt to eliminate cache contention
4580 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4581 uint array_length = PADDING_ELEM_NUM +
4582 real_length +
4583 PADDING_ELEM_NUM;
4584 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4585 if (_surviving_young_words_base == NULL)
4586 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4587 "Not enough space for young surv histo.");
4588 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4589 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4590
4591 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4592 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4593
4594 _start = os::elapsedTime();
4595 }
4596
4597 void
4598 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4599 {
4600 st->print_raw_cr("GC Termination Stats");
4601 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4602 " ------waste (KiB)------");
4603 st->print_raw_cr("thr ms ms % ms % attempts"
4604 " total alloc undo");
4605 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4606 " ------- ------- -------");
4607 }
4608
4609 void
4610 G1ParScanThreadState::print_termination_stats(int i,
4611 outputStream* const st) const
4612 {
4613 const double elapsed_ms = elapsed_time() * 1000.0;
4614 const double s_roots_ms = strong_roots_time() * 1000.0;
4615 const double term_ms = term_time() * 1000.0;
4616 st->print_cr("%3d %9.2f %9.2f %6.2f "
4617 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4618 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4619 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4620 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4621 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4622 alloc_buffer_waste() * HeapWordSize / K,
4623 undo_waste() * HeapWordSize / K);
4624 }
4625
4626 #ifdef ASSERT
4627 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4628 assert(ref != NULL, "invariant");
4629 assert(UseCompressedOops, "sanity");
4630 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4631 oop p = oopDesc::load_decode_heap_oop(ref);
4632 assert(_g1h->is_in_g1_reserved(p),
4633 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4634 return true;
4635 }
4636
4637 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4638 assert(ref != NULL, "invariant");
4639 if (has_partial_array_mask(ref)) {
4640 // Must be in the collection set--it's already been copied.
4641 oop p = clear_partial_array_mask(ref);
4642 assert(_g1h->obj_in_cs(p),
4643 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4644 } else {
4645 oop p = oopDesc::load_decode_heap_oop(ref);
4646 assert(_g1h->is_in_g1_reserved(p),
4647 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4648 }
4649 return true;
4650 }
4651
4652 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4653 if (ref.is_narrow()) {
4654 return verify_ref((narrowOop*) ref);
4655 } else {
4656 return verify_ref((oop*) ref);
4657 }
4658 }
4659 #endif // ASSERT
4660
4661 void G1ParScanThreadState::trim_queue() {
4662 assert(_evac_failure_cl != NULL, "not set");
4663
4664 StarTask ref;
4665 do {
4666 // Drain the overflow stack first, so other threads can steal.
4667 while (refs()->pop_overflow(ref)) {
4668 deal_with_reference(ref);
4669 }
4670
4671 while (refs()->pop_local(ref)) {
4672 deal_with_reference(ref);
4673 }
4674 } while (!refs()->is_empty());
4675 }
4676
4677 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4678 G1ParScanThreadState* par_scan_state) :
4679 _g1(g1), _par_scan_state(par_scan_state),
4680 _worker_id(par_scan_state->queue_num()) { }
4681
4682 void G1ParCopyHelper::mark_object(oop obj) {
4683 #ifdef ASSERT
4684 HeapRegion* hr = _g1->heap_region_containing(obj);
4685 assert(hr != NULL, "sanity");
4686 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4687 #endif // ASSERT
4688
4689 // We know that the object is not moving so it's safe to read its size.
4690 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4691 }
4692
4693 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4694 #ifdef ASSERT
4695 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4696 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4697 assert(from_obj != to_obj, "should not be self-forwarded");
4698
4699 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4700 assert(from_hr != NULL, "sanity");
4701 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4702
4703 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4704 assert(to_hr != NULL, "sanity");
4705 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4706 #endif // ASSERT
4707
4708 // The object might be in the process of being copied by another
4709 // worker so we cannot trust that its to-space image is
4710 // well-formed. So we have to read its size from its from-space
4711 // image which we know should not be changing.
4712 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4713 }
4714
4715 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4716 size_t word_sz = old->size();
4717 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4718 // +1 to make the -1 indexes valid...
4719 int young_index = from_region->young_index_in_cset()+1;
4720 assert( (from_region->is_young() && young_index > 0) ||
4721 (!from_region->is_young() && young_index == 0), "invariant" );
4722 G1CollectorPolicy* g1p = _g1h->g1_policy();
4723 markOop m = old->mark();
4724 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4725 : m->age();
4726 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4727 word_sz);
4728 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4729 #ifndef PRODUCT
4730 // Should this evacuation fail?
4731 if (_g1h->evacuation_should_fail()) {
4732 if (obj_ptr != NULL) {
4733 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4734 obj_ptr = NULL;
4735 }
4736 }
4737 #endif // !PRODUCT
4738
4739 if (obj_ptr == NULL) {
4740 // This will either forward-to-self, or detect that someone else has
4741 // installed a forwarding pointer.
4742 return _g1h->handle_evacuation_failure_par(this, old);
4743 }
4744
4745 oop obj = oop(obj_ptr);
4746
4747 // We're going to allocate linearly, so might as well prefetch ahead.
4748 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4749
4750 oop forward_ptr = old->forward_to_atomic(obj);
4751 if (forward_ptr == NULL) {
4752 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4753
4754 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4755 // we actually allocated from and update alloc_purpose accordingly
4756 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4757 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4758
4759 if (g1p->track_object_age(alloc_purpose)) {
4760 // We could simply do obj->incr_age(). However, this causes a
4761 // performance issue. obj->incr_age() will first check whether
4762 // the object has a displaced mark by checking its mark word;
4763 // getting the mark word from the new location of the object
4764 // stalls. So, given that we already have the mark word and we
4765 // are about to install it anyway, it's better to increase the
4766 // age on the mark word, when the object does not have a
4767 // displaced mark word. We're not expecting many objects to have
4768 // a displaced marked word, so that case is not optimized
4769 // further (it could be...) and we simply call obj->incr_age().
4770
4771 if (m->has_displaced_mark_helper()) {
4772 // in this case, we have to install the mark word first,
4773 // otherwise obj looks to be forwarded (the old mark word,
4774 // which contains the forward pointer, was copied)
4775 obj->set_mark(m);
4776 obj->incr_age();
4777 } else {
4778 m = m->incr_age();
4779 obj->set_mark(m);
4780 }
4781 age_table()->add(obj, word_sz);
4782 } else {
4783 obj->set_mark(m);
4784 }
4785
4786 if (G1StringDedup::is_enabled()) {
4787 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4788 to_region->is_young(),
4789 queue_num(),
4790 obj);
4791 }
4792
4793 size_t* surv_young_words = surviving_young_words();
4794 surv_young_words[young_index] += word_sz;
4795
4796 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4797 // We keep track of the next start index in the length field of
4798 // the to-space object. The actual length can be found in the
4799 // length field of the from-space object.
4800 arrayOop(obj)->set_length(0);
4801 oop* old_p = set_partial_array_mask(old);
4802 push_on_queue(old_p);
4803 } else {
4804 // No point in using the slower heap_region_containing() method,
4805 // given that we know obj is in the heap.
4806 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4807 obj->oop_iterate_backwards(&_scanner);
4808 }
4809 } else {
4810 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4811 obj = forward_ptr;
4812 }
4813 return obj;
4814 }
4815
4816 template <class T>
4817 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4818 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4819 _scanned_klass->record_modified_oops();
4820 }
4821 }
4822
4823 template <G1Barrier barrier, bool do_mark_object>
4824 template <class T>
4825 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4826 T heap_oop = oopDesc::load_heap_oop(p);
4827
4828 if (oopDesc::is_null(heap_oop)) {
4829 return;
4830 }
4831
4832 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4833
4834 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4835
4836 if (_g1->in_cset_fast_test(obj)) {
4837 oop forwardee;
4838 if (obj->is_forwarded()) {
4839 forwardee = obj->forwardee();
4840 } else {
4841 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4842 }
4843 assert(forwardee != NULL, "forwardee should not be NULL");
4844 oopDesc::encode_store_heap_oop(p, forwardee);
4845 if (do_mark_object && forwardee != obj) {
4846 // If the object is self-forwarded we don't need to explicitly
4847 // mark it, the evacuation failure protocol will do so.
4848 mark_forwarded_object(obj, forwardee);
4849 }
4850
4851 if (barrier == G1BarrierKlass) {
4852 do_klass_barrier(p, forwardee);
4853 }
4854 } else {
4855 // The object is not in collection set. If we're a root scanning
4856 // closure during an initial mark pause (i.e. do_mark_object will
4857 // be true) then attempt to mark the object.
4858 if (do_mark_object) {
4859 mark_object(obj);
4860 }
4861 }
4862
4863 if (barrier == G1BarrierEvac) {
4864 _par_scan_state->update_rs(_from, p, _worker_id);
4865 }
4866 }
4867
4868 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4869 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4870
4871 class G1ParEvacuateFollowersClosure : public VoidClosure {
4872 protected:
4873 G1CollectedHeap* _g1h;
4874 G1ParScanThreadState* _par_scan_state;
4875 RefToScanQueueSet* _queues;
4876 ParallelTaskTerminator* _terminator;
4877
4878 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4879 RefToScanQueueSet* queues() { return _queues; }
4880 ParallelTaskTerminator* terminator() { return _terminator; }
4881
4882 public:
4883 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4884 G1ParScanThreadState* par_scan_state,
4885 RefToScanQueueSet* queues,
4886 ParallelTaskTerminator* terminator)
4887 : _g1h(g1h), _par_scan_state(par_scan_state),
4888 _queues(queues), _terminator(terminator) {}
4889
4890 void do_void();
4891
4892 private:
4893 inline bool offer_termination();
4894 };
4895
4896 bool G1ParEvacuateFollowersClosure::offer_termination() {
4897 G1ParScanThreadState* const pss = par_scan_state();
4898 pss->start_term_time();
4899 const bool res = terminator()->offer_termination();
4900 pss->end_term_time();
4901 return res;
4902 }
4903
4904 void G1ParEvacuateFollowersClosure::do_void() {
4905 StarTask stolen_task;
4906 G1ParScanThreadState* const pss = par_scan_state();
4907 pss->trim_queue();
4908
4909 do {
4910 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4911 assert(pss->verify_task(stolen_task), "sanity");
4912 if (stolen_task.is_narrow()) {
4913 pss->deal_with_reference((narrowOop*) stolen_task);
4914 } else {
4915 pss->deal_with_reference((oop*) stolen_task);
4916 }
4917
4918 // We've just processed a reference and we might have made
4919 // available new entries on the queues. So we have to make sure
4920 // we drain the queues as necessary.
4921 pss->trim_queue();
4922 }
4923 } while (!offer_termination());
4924 }
4925
4926 class G1KlassScanClosure : public KlassClosure {
4927 G1ParCopyHelper* _closure;
4928 bool _process_only_dirty;
4929 int _count;
4930 public:
4931 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4932 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4933 void do_klass(Klass* klass) {
4934 // If the klass has not been dirtied we know that there's
4935 // no references into the young gen and we can skip it.
4936 if (!_process_only_dirty || klass->has_modified_oops()) {
4937 // Clean the klass since we're going to scavenge all the metadata.
4938 klass->clear_modified_oops();
4939
4940 // Tell the closure that this klass is the Klass to scavenge
4941 // and is the one to dirty if oops are left pointing into the young gen.
4942 _closure->set_scanned_klass(klass);
4943
4944 klass->oops_do(_closure);
4945
4946 _closure->set_scanned_klass(NULL);
4947 }
4948 _count++;
4949 }
4950 };
4951
4952 class G1ParTask : public AbstractGangTask {
4953 protected:
4954 G1CollectedHeap* _g1h;
4955 RefToScanQueueSet *_queues;
4956 ParallelTaskTerminator _terminator;
4957 uint _n_workers;
4958
4959 Mutex _stats_lock;
4960 Mutex* stats_lock() { return &_stats_lock; }
4961
4962 size_t getNCards() {
4963 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4964 / G1BlockOffsetSharedArray::N_bytes;
4965 }
4966
4967 public:
4968 G1ParTask(G1CollectedHeap* g1h,
4969 RefToScanQueueSet *task_queues)
4970 : AbstractGangTask("G1 collection"),
4971 _g1h(g1h),
4972 _queues(task_queues),
4973 _terminator(0, _queues),
4974 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4975 {}
4976
4977 RefToScanQueueSet* queues() { return _queues; }
4978
4979 RefToScanQueue *work_queue(int i) {
4980 return queues()->queue(i);
4981 }
4982
4983 ParallelTaskTerminator* terminator() { return &_terminator; }
4984
4985 virtual void set_for_termination(int active_workers) {
4986 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4987 // in the young space (_par_seq_tasks) in the G1 heap
4988 // for SequentialSubTasksDone.
4989 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4990 // both of which need setting by set_n_termination().
4991 _g1h->SharedHeap::set_n_termination(active_workers);
4992 _g1h->set_n_termination(active_workers);
4993 terminator()->reset_for_reuse(active_workers);
4994 _n_workers = active_workers;
4995 }
4996
4997 void work(uint worker_id) {
4998 if (worker_id >= _n_workers) return; // no work needed this round
4999
5000 double start_time_ms = os::elapsedTime() * 1000.0;
5001 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5002
5003 {
5004 ResourceMark rm;
5005 HandleMark hm;
5006
5007 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5008
5009 G1ParScanThreadState pss(_g1h, worker_id, rp);
5010 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5011
5012 pss.set_evac_failure_closure(&evac_failure_cl);
5013
5014 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5015 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5016
5017 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5018 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5019
5020 bool only_young = _g1h->g1_policy()->gcs_are_young();
5021 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5022 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5023
5024 OopClosure* scan_root_cl = &only_scan_root_cl;
5025 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5026
5027 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5028 // We also need to mark copied objects.
5029 scan_root_cl = &scan_mark_root_cl;
5030 scan_klasses_cl = &scan_mark_klasses_cl_s;
5031 }
5032
5033 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5034
5035 // Don't scan the scavengable methods in the code cache as part
5036 // of strong root scanning. The code roots that point into a
5037 // region in the collection set are scanned when we scan the
5038 // region's RSet.
5039 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5040
5041 pss.start_strong_roots();
5042 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5043 SharedHeap::ScanningOption(so),
5044 scan_root_cl,
5045 &push_heap_rs_cl,
5046 scan_klasses_cl,
5047 worker_id);
5048 pss.end_strong_roots();
5049
5050 {
5051 double start = os::elapsedTime();
5052 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5053 evac.do_void();
5054 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5055 double term_ms = pss.term_time()*1000.0;
5056 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5057 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5058 }
5059 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5060 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5061
5062 if (ParallelGCVerbose) {
5063 MutexLocker x(stats_lock());
5064 pss.print_termination_stats(worker_id);
5065 }
5066
5067 assert(pss.refs()->is_empty(), "should be empty");
5068
5069 // Close the inner scope so that the ResourceMark and HandleMark
5070 // destructors are executed here and are included as part of the
5071 // "GC Worker Time".
5072 }
5073
5074 double end_time_ms = os::elapsedTime() * 1000.0;
5075 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5076 }
5077 };
5078
5079 // *** Common G1 Evacuation Stuff
5080
5081 // This method is run in a GC worker.
5082
5083 void
5084 G1CollectedHeap::
5085 g1_process_strong_roots(bool is_scavenging,
5086 ScanningOption so,
5087 OopClosure* scan_non_heap_roots,
5088 OopsInHeapRegionClosure* scan_rs,
5089 G1KlassScanClosure* scan_klasses,
5090 uint worker_i) {
5091
5092 // First scan the strong roots
5093 double ext_roots_start = os::elapsedTime();
5094 double closure_app_time_sec = 0.0;
5095
5096 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5097
5098 process_strong_roots(false, // no scoping; this is parallel code
5099 so,
5100 &buf_scan_non_heap_roots,
5101 scan_klasses
5102 );
5103
5104 // Now the CM ref_processor roots.
5105 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5106 // We need to treat the discovered reference lists of the
5107 // concurrent mark ref processor as roots and keep entries
5108 // (which are added by the marking threads) on them live
5109 // until they can be processed at the end of marking.
5110 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5111 }
5112
5113 // Finish up any enqueued closure apps (attributed as object copy time).
5114 buf_scan_non_heap_roots.done();
5115
5116 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5117
5118 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5119
5120 double ext_root_time_ms =
5121 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5122
5123 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5124
5125 // During conc marking we have to filter the per-thread SATB buffers
5126 // to make sure we remove any oops into the CSet (which will show up
5127 // as implicitly live).
5128 double satb_filtering_ms = 0.0;
5129 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5130 if (mark_in_progress()) {
5131 double satb_filter_start = os::elapsedTime();
5132
5133 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5134
5135 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5136 }
5137 }
5138 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5139
5140 // If this is an initial mark pause, and we're not scanning
5141 // the entire code cache, we need to mark the oops in the
5142 // strong code root lists for the regions that are not in
5143 // the collection set.
5144 // Note all threads participate in this set of root tasks.
5145 double mark_strong_code_roots_ms = 0.0;
5146 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5147 double mark_strong_roots_start = os::elapsedTime();
5148 mark_strong_code_roots(worker_i);
5149 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5150 }
5151 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5152
5153 // Now scan the complement of the collection set.
5154 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5155 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5156
5157 _process_strong_tasks->all_tasks_completed();
5158 }
5159
5160 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5161 private:
5162 BoolObjectClosure* _is_alive;
5163 int _initial_string_table_size;
5164 int _initial_symbol_table_size;
5165
5166 bool _process_strings;
5167 int _strings_processed;
5168 int _strings_removed;
5169
5170 bool _process_symbols;
5171 int _symbols_processed;
5172 int _symbols_removed;
5173
5174 bool _do_in_parallel;
5175 public:
5176 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5177 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5178 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5179 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5180 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5181
5182 _initial_string_table_size = StringTable::the_table()->table_size();
5183 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5184 if (process_strings) {
5185 StringTable::clear_parallel_claimed_index();
5186 }
5187 if (process_symbols) {
5188 SymbolTable::clear_parallel_claimed_index();
5189 }
5190 }
5191
5192 ~G1StringSymbolTableUnlinkTask() {
5193 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5194 err_msg("claim value %d after unlink less than initial string table size %d",
5195 StringTable::parallel_claimed_index(), _initial_string_table_size));
5196 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5197 err_msg("claim value %d after unlink less than initial symbol table size %d",
5198 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5199 }
5200
5201 void work(uint worker_id) {
5202 if (_do_in_parallel) {
5203 int strings_processed = 0;
5204 int strings_removed = 0;
5205 int symbols_processed = 0;
5206 int symbols_removed = 0;
5207 if (_process_strings) {
5208 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5209 Atomic::add(strings_processed, &_strings_processed);
5210 Atomic::add(strings_removed, &_strings_removed);
5211 }
5212 if (_process_symbols) {
5213 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5214 Atomic::add(symbols_processed, &_symbols_processed);
5215 Atomic::add(symbols_removed, &_symbols_removed);
5216 }
5217 } else {
5218 if (_process_strings) {
5219 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5220 }
5221 if (_process_symbols) {
5222 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5223 }
5224 }
5225 }
5226
5227 size_t strings_processed() const { return (size_t)_strings_processed; }
5228 size_t strings_removed() const { return (size_t)_strings_removed; }
5229
5230 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5231 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5232 };
5233
5234 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5235 bool process_strings, bool process_symbols) {
5236 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5237 _g1h->workers()->active_workers() : 1);
5238
5239 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5240 if (G1CollectedHeap::use_parallel_gc_threads()) {
5241 set_par_threads(n_workers);
5242 workers()->run_task(&g1_unlink_task);
5243 set_par_threads(0);
5244 } else {
5245 g1_unlink_task.work(0);
5246 }
5247 if (G1TraceStringSymbolTableScrubbing) {
5248 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5249 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5250 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5251 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5252 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5253 }
5254
5255 if (G1StringDedup::is_enabled()) {
5256 G1StringDedup::unlink(is_alive);
5257 }
5258 }
5259
5260 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
5261 public:
5262 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
5263 *card_ptr = CardTableModRefBS::dirty_card_val();
5264 return true;
5265 }
5266 };
5267
5268 void G1CollectedHeap::redirty_logged_cards() {
5269 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5270 double redirty_logged_cards_start = os::elapsedTime();
5271
5272 RedirtyLoggedCardTableEntryFastClosure redirty;
5273 dirty_card_queue_set().set_closure(&redirty);
5274 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5275
5276 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5277 dcq.merge_bufferlists(&dirty_card_queue_set());
5278 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5279
5280 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5281 }
5282
5283 // Weak Reference Processing support
5284
5285 // An always "is_alive" closure that is used to preserve referents.
5286 // If the object is non-null then it's alive. Used in the preservation
5287 // of referent objects that are pointed to by reference objects
5288 // discovered by the CM ref processor.
5289 class G1AlwaysAliveClosure: public BoolObjectClosure {
5290 G1CollectedHeap* _g1;
5291 public:
5292 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5293 bool do_object_b(oop p) {
5294 if (p != NULL) {
5295 return true;
5296 }
5297 return false;
5298 }
5299 };
5300
5301 bool G1STWIsAliveClosure::do_object_b(oop p) {
5302 // An object is reachable if it is outside the collection set,
5303 // or is inside and copied.
5304 return !_g1->obj_in_cs(p) || p->is_forwarded();
5305 }
5306
5307 // Non Copying Keep Alive closure
5308 class G1KeepAliveClosure: public OopClosure {
5309 G1CollectedHeap* _g1;
5310 public:
5311 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5312 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5313 void do_oop( oop* p) {
5314 oop obj = *p;
5315
5316 if (_g1->obj_in_cs(obj)) {
5317 assert( obj->is_forwarded(), "invariant" );
5318 *p = obj->forwardee();
5319 }
5320 }
5321 };
5322
5323 // Copying Keep Alive closure - can be called from both
5324 // serial and parallel code as long as different worker
5325 // threads utilize different G1ParScanThreadState instances
5326 // and different queues.
5327
5328 class G1CopyingKeepAliveClosure: public OopClosure {
5329 G1CollectedHeap* _g1h;
5330 OopClosure* _copy_non_heap_obj_cl;
5331 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5332 G1ParScanThreadState* _par_scan_state;
5333
5334 public:
5335 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5336 OopClosure* non_heap_obj_cl,
5337 OopsInHeapRegionClosure* metadata_obj_cl,
5338 G1ParScanThreadState* pss):
5339 _g1h(g1h),
5340 _copy_non_heap_obj_cl(non_heap_obj_cl),
5341 _copy_metadata_obj_cl(metadata_obj_cl),
5342 _par_scan_state(pss)
5343 {}
5344
5345 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5346 virtual void do_oop( oop* p) { do_oop_work(p); }
5347
5348 template <class T> void do_oop_work(T* p) {
5349 oop obj = oopDesc::load_decode_heap_oop(p);
5350
5351 if (_g1h->obj_in_cs(obj)) {
5352 // If the referent object has been forwarded (either copied
5353 // to a new location or to itself in the event of an
5354 // evacuation failure) then we need to update the reference
5355 // field and, if both reference and referent are in the G1
5356 // heap, update the RSet for the referent.
5357 //
5358 // If the referent has not been forwarded then we have to keep
5359 // it alive by policy. Therefore we have copy the referent.
5360 //
5361 // If the reference field is in the G1 heap then we can push
5362 // on the PSS queue. When the queue is drained (after each
5363 // phase of reference processing) the object and it's followers
5364 // will be copied, the reference field set to point to the
5365 // new location, and the RSet updated. Otherwise we need to
5366 // use the the non-heap or metadata closures directly to copy
5367 // the referent object and update the pointer, while avoiding
5368 // updating the RSet.
5369
5370 if (_g1h->is_in_g1_reserved(p)) {
5371 _par_scan_state->push_on_queue(p);
5372 } else {
5373 assert(!ClassLoaderDataGraph::contains((address)p),
5374 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5375 PTR_FORMAT, p));
5376 _copy_non_heap_obj_cl->do_oop(p);
5377 }
5378 }
5379 }
5380 };
5381
5382 // Serial drain queue closure. Called as the 'complete_gc'
5383 // closure for each discovered list in some of the
5384 // reference processing phases.
5385
5386 class G1STWDrainQueueClosure: public VoidClosure {
5387 protected:
5388 G1CollectedHeap* _g1h;
5389 G1ParScanThreadState* _par_scan_state;
5390
5391 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5392
5393 public:
5394 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5395 _g1h(g1h),
5396 _par_scan_state(pss)
5397 { }
5398
5399 void do_void() {
5400 G1ParScanThreadState* const pss = par_scan_state();
5401 pss->trim_queue();
5402 }
5403 };
5404
5405 // Parallel Reference Processing closures
5406
5407 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5408 // processing during G1 evacuation pauses.
5409
5410 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5411 private:
5412 G1CollectedHeap* _g1h;
5413 RefToScanQueueSet* _queues;
5414 FlexibleWorkGang* _workers;
5415 int _active_workers;
5416
5417 public:
5418 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5419 FlexibleWorkGang* workers,
5420 RefToScanQueueSet *task_queues,
5421 int n_workers) :
5422 _g1h(g1h),
5423 _queues(task_queues),
5424 _workers(workers),
5425 _active_workers(n_workers)
5426 {
5427 assert(n_workers > 0, "shouldn't call this otherwise");
5428 }
5429
5430 // Executes the given task using concurrent marking worker threads.
5431 virtual void execute(ProcessTask& task);
5432 virtual void execute(EnqueueTask& task);
5433 };
5434
5435 // Gang task for possibly parallel reference processing
5436
5437 class G1STWRefProcTaskProxy: public AbstractGangTask {
5438 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5439 ProcessTask& _proc_task;
5440 G1CollectedHeap* _g1h;
5441 RefToScanQueueSet *_task_queues;
5442 ParallelTaskTerminator* _terminator;
5443
5444 public:
5445 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5446 G1CollectedHeap* g1h,
5447 RefToScanQueueSet *task_queues,
5448 ParallelTaskTerminator* terminator) :
5449 AbstractGangTask("Process reference objects in parallel"),
5450 _proc_task(proc_task),
5451 _g1h(g1h),
5452 _task_queues(task_queues),
5453 _terminator(terminator)
5454 {}
5455
5456 virtual void work(uint worker_id) {
5457 // The reference processing task executed by a single worker.
5458 ResourceMark rm;
5459 HandleMark hm;
5460
5461 G1STWIsAliveClosure is_alive(_g1h);
5462
5463 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5464 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5465
5466 pss.set_evac_failure_closure(&evac_failure_cl);
5467
5468 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5469 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5470
5471 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5472 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5473
5474 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5475 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5476
5477 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5478 // We also need to mark copied objects.
5479 copy_non_heap_cl = ©_mark_non_heap_cl;
5480 copy_metadata_cl = ©_mark_metadata_cl;
5481 }
5482
5483 // Keep alive closure.
5484 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5485
5486 // Complete GC closure
5487 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5488
5489 // Call the reference processing task's work routine.
5490 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5491
5492 // Note we cannot assert that the refs array is empty here as not all
5493 // of the processing tasks (specifically phase2 - pp2_work) execute
5494 // the complete_gc closure (which ordinarily would drain the queue) so
5495 // the queue may not be empty.
5496 }
5497 };
5498
5499 // Driver routine for parallel reference processing.
5500 // Creates an instance of the ref processing gang
5501 // task and has the worker threads execute it.
5502 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5503 assert(_workers != NULL, "Need parallel worker threads.");
5504
5505 ParallelTaskTerminator terminator(_active_workers, _queues);
5506 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5507
5508 _g1h->set_par_threads(_active_workers);
5509 _workers->run_task(&proc_task_proxy);
5510 _g1h->set_par_threads(0);
5511 }
5512
5513 // Gang task for parallel reference enqueueing.
5514
5515 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5516 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5517 EnqueueTask& _enq_task;
5518
5519 public:
5520 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5521 AbstractGangTask("Enqueue reference objects in parallel"),
5522 _enq_task(enq_task)
5523 { }
5524
5525 virtual void work(uint worker_id) {
5526 _enq_task.work(worker_id);
5527 }
5528 };
5529
5530 // Driver routine for parallel reference enqueueing.
5531 // Creates an instance of the ref enqueueing gang
5532 // task and has the worker threads execute it.
5533
5534 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5535 assert(_workers != NULL, "Need parallel worker threads.");
5536
5537 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5538
5539 _g1h->set_par_threads(_active_workers);
5540 _workers->run_task(&enq_task_proxy);
5541 _g1h->set_par_threads(0);
5542 }
5543
5544 // End of weak reference support closures
5545
5546 // Abstract task used to preserve (i.e. copy) any referent objects
5547 // that are in the collection set and are pointed to by reference
5548 // objects discovered by the CM ref processor.
5549
5550 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5551 protected:
5552 G1CollectedHeap* _g1h;
5553 RefToScanQueueSet *_queues;
5554 ParallelTaskTerminator _terminator;
5555 uint _n_workers;
5556
5557 public:
5558 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5559 AbstractGangTask("ParPreserveCMReferents"),
5560 _g1h(g1h),
5561 _queues(task_queues),
5562 _terminator(workers, _queues),
5563 _n_workers(workers)
5564 { }
5565
5566 void work(uint worker_id) {
5567 ResourceMark rm;
5568 HandleMark hm;
5569
5570 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5571 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5572
5573 pss.set_evac_failure_closure(&evac_failure_cl);
5574
5575 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5576
5577
5578 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5579 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5580
5581 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5582 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5583
5584 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5585 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5586
5587 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5588 // We also need to mark copied objects.
5589 copy_non_heap_cl = ©_mark_non_heap_cl;
5590 copy_metadata_cl = ©_mark_metadata_cl;
5591 }
5592
5593 // Is alive closure
5594 G1AlwaysAliveClosure always_alive(_g1h);
5595
5596 // Copying keep alive closure. Applied to referent objects that need
5597 // to be copied.
5598 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5599
5600 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5601
5602 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5603 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5604
5605 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5606 // So this must be true - but assert just in case someone decides to
5607 // change the worker ids.
5608 assert(0 <= worker_id && worker_id < limit, "sanity");
5609 assert(!rp->discovery_is_atomic(), "check this code");
5610
5611 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5612 for (uint idx = worker_id; idx < limit; idx += stride) {
5613 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5614
5615 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5616 while (iter.has_next()) {
5617 // Since discovery is not atomic for the CM ref processor, we
5618 // can see some null referent objects.
5619 iter.load_ptrs(DEBUG_ONLY(true));
5620 oop ref = iter.obj();
5621
5622 // This will filter nulls.
5623 if (iter.is_referent_alive()) {
5624 iter.make_referent_alive();
5625 }
5626 iter.move_to_next();
5627 }
5628 }
5629
5630 // Drain the queue - which may cause stealing
5631 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5632 drain_queue.do_void();
5633 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5634 assert(pss.refs()->is_empty(), "should be");
5635 }
5636 };
5637
5638 // Weak Reference processing during an evacuation pause (part 1).
5639 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5640 double ref_proc_start = os::elapsedTime();
5641
5642 ReferenceProcessor* rp = _ref_processor_stw;
5643 assert(rp->discovery_enabled(), "should have been enabled");
5644
5645 // Any reference objects, in the collection set, that were 'discovered'
5646 // by the CM ref processor should have already been copied (either by
5647 // applying the external root copy closure to the discovered lists, or
5648 // by following an RSet entry).
5649 //
5650 // But some of the referents, that are in the collection set, that these
5651 // reference objects point to may not have been copied: the STW ref
5652 // processor would have seen that the reference object had already
5653 // been 'discovered' and would have skipped discovering the reference,
5654 // but would not have treated the reference object as a regular oop.
5655 // As a result the copy closure would not have been applied to the
5656 // referent object.
5657 //
5658 // We need to explicitly copy these referent objects - the references
5659 // will be processed at the end of remarking.
5660 //
5661 // We also need to do this copying before we process the reference
5662 // objects discovered by the STW ref processor in case one of these
5663 // referents points to another object which is also referenced by an
5664 // object discovered by the STW ref processor.
5665
5666 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5667 no_of_gc_workers == workers()->active_workers(),
5668 "Need to reset active GC workers");
5669
5670 set_par_threads(no_of_gc_workers);
5671 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5672 no_of_gc_workers,
5673 _task_queues);
5674
5675 if (G1CollectedHeap::use_parallel_gc_threads()) {
5676 workers()->run_task(&keep_cm_referents);
5677 } else {
5678 keep_cm_referents.work(0);
5679 }
5680
5681 set_par_threads(0);
5682
5683 // Closure to test whether a referent is alive.
5684 G1STWIsAliveClosure is_alive(this);
5685
5686 // Even when parallel reference processing is enabled, the processing
5687 // of JNI refs is serial and performed serially by the current thread
5688 // rather than by a worker. The following PSS will be used for processing
5689 // JNI refs.
5690
5691 // Use only a single queue for this PSS.
5692 G1ParScanThreadState pss(this, 0, NULL);
5693
5694 // We do not embed a reference processor in the copying/scanning
5695 // closures while we're actually processing the discovered
5696 // reference objects.
5697 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5698
5699 pss.set_evac_failure_closure(&evac_failure_cl);
5700
5701 assert(pss.refs()->is_empty(), "pre-condition");
5702
5703 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5704 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5705
5706 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5707 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5708
5709 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5710 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5711
5712 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5713 // We also need to mark copied objects.
5714 copy_non_heap_cl = ©_mark_non_heap_cl;
5715 copy_metadata_cl = ©_mark_metadata_cl;
5716 }
5717
5718 // Keep alive closure.
5719 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5720
5721 // Serial Complete GC closure
5722 G1STWDrainQueueClosure drain_queue(this, &pss);
5723
5724 // Setup the soft refs policy...
5725 rp->setup_policy(false);
5726
5727 ReferenceProcessorStats stats;
5728 if (!rp->processing_is_mt()) {
5729 // Serial reference processing...
5730 stats = rp->process_discovered_references(&is_alive,
5731 &keep_alive,
5732 &drain_queue,
5733 NULL,
5734 _gc_timer_stw);
5735 } else {
5736 // Parallel reference processing
5737 assert(rp->num_q() == no_of_gc_workers, "sanity");
5738 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5739
5740 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5741 stats = rp->process_discovered_references(&is_alive,
5742 &keep_alive,
5743 &drain_queue,
5744 &par_task_executor,
5745 _gc_timer_stw);
5746 }
5747
5748 _gc_tracer_stw->report_gc_reference_stats(stats);
5749
5750 // We have completed copying any necessary live referent objects.
5751 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5752
5753 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5754 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5755 }
5756
5757 // Weak Reference processing during an evacuation pause (part 2).
5758 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5759 double ref_enq_start = os::elapsedTime();
5760
5761 ReferenceProcessor* rp = _ref_processor_stw;
5762 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5763
5764 // Now enqueue any remaining on the discovered lists on to
5765 // the pending list.
5766 if (!rp->processing_is_mt()) {
5767 // Serial reference processing...
5768 rp->enqueue_discovered_references();
5769 } else {
5770 // Parallel reference enqueueing
5771
5772 assert(no_of_gc_workers == workers()->active_workers(),
5773 "Need to reset active workers");
5774 assert(rp->num_q() == no_of_gc_workers, "sanity");
5775 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5776
5777 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5778 rp->enqueue_discovered_references(&par_task_executor);
5779 }
5780
5781 rp->verify_no_references_recorded();
5782 assert(!rp->discovery_enabled(), "should have been disabled");
5783
5784 // FIXME
5785 // CM's reference processing also cleans up the string and symbol tables.
5786 // Should we do that here also? We could, but it is a serial operation
5787 // and could significantly increase the pause time.
5788
5789 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5790 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5791 }
5792
5793 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5794 _expand_heap_after_alloc_failure = true;
5795 _evacuation_failed = false;
5796
5797 // Should G1EvacuationFailureALot be in effect for this GC?
5798 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5799
5800 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5801
5802 // Disable the hot card cache.
5803 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5804 hot_card_cache->reset_hot_cache_claimed_index();
5805 hot_card_cache->set_use_cache(false);
5806
5807 uint n_workers;
5808 if (G1CollectedHeap::use_parallel_gc_threads()) {
5809 n_workers =
5810 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5811 workers()->active_workers(),
5812 Threads::number_of_non_daemon_threads());
5813 assert(UseDynamicNumberOfGCThreads ||
5814 n_workers == workers()->total_workers(),
5815 "If not dynamic should be using all the workers");
5816 workers()->set_active_workers(n_workers);
5817 set_par_threads(n_workers);
5818 } else {
5819 assert(n_par_threads() == 0,
5820 "Should be the original non-parallel value");
5821 n_workers = 1;
5822 }
5823
5824 G1ParTask g1_par_task(this, _task_queues);
5825
5826 init_for_evac_failure(NULL);
5827
5828 rem_set()->prepare_for_younger_refs_iterate(true);
5829
5830 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5831 double start_par_time_sec = os::elapsedTime();
5832 double end_par_time_sec;
5833
5834 {
5835 StrongRootsScope srs(this);
5836
5837 if (G1CollectedHeap::use_parallel_gc_threads()) {
5838 // The individual threads will set their evac-failure closures.
5839 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5840 // These tasks use ShareHeap::_process_strong_tasks
5841 assert(UseDynamicNumberOfGCThreads ||
5842 workers()->active_workers() == workers()->total_workers(),
5843 "If not dynamic should be using all the workers");
5844 workers()->run_task(&g1_par_task);
5845 } else {
5846 g1_par_task.set_for_termination(n_workers);
5847 g1_par_task.work(0);
5848 }
5849 end_par_time_sec = os::elapsedTime();
5850
5851 // Closing the inner scope will execute the destructor
5852 // for the StrongRootsScope object. We record the current
5853 // elapsed time before closing the scope so that time
5854 // taken for the SRS destructor is NOT included in the
5855 // reported parallel time.
5856 }
5857
5858 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5859 g1_policy()->phase_times()->record_par_time(par_time_ms);
5860
5861 double code_root_fixup_time_ms =
5862 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5863 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5864
5865 set_par_threads(0);
5866
5867 // Process any discovered reference objects - we have
5868 // to do this _before_ we retire the GC alloc regions
5869 // as we may have to copy some 'reachable' referent
5870 // objects (and their reachable sub-graphs) that were
5871 // not copied during the pause.
5872 process_discovered_references(n_workers);
5873
5874 // Weak root processing.
5875 {
5876 G1STWIsAliveClosure is_alive(this);
5877 G1KeepAliveClosure keep_alive(this);
5878 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5879 if (G1StringDedup::is_enabled()) {
5880 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5881 }
5882 }
5883
5884 release_gc_alloc_regions(n_workers, evacuation_info);
5885 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5886
5887 // Reset and re-enable the hot card cache.
5888 // Note the counts for the cards in the regions in the
5889 // collection set are reset when the collection set is freed.
5890 hot_card_cache->reset_hot_cache();
5891 hot_card_cache->set_use_cache(true);
5892
5893 // Migrate the strong code roots attached to each region in
5894 // the collection set. Ideally we would like to do this
5895 // after we have finished the scanning/evacuation of the
5896 // strong code roots for a particular heap region.
5897 migrate_strong_code_roots();
5898
5899 purge_code_root_memory();
5900
5901 if (g1_policy()->during_initial_mark_pause()) {
5902 // Reset the claim values set during marking the strong code roots
5903 reset_heap_region_claim_values();
5904 }
5905
5906 finalize_for_evac_failure();
5907
5908 if (evacuation_failed()) {
5909 remove_self_forwarding_pointers();
5910
5911 // Reset the G1EvacuationFailureALot counters and flags
5912 // Note: the values are reset only when an actual
5913 // evacuation failure occurs.
5914 NOT_PRODUCT(reset_evacuation_should_fail();)
5915 }
5916
5917 // Enqueue any remaining references remaining on the STW
5918 // reference processor's discovered lists. We need to do
5919 // this after the card table is cleaned (and verified) as
5920 // the act of enqueueing entries on to the pending list
5921 // will log these updates (and dirty their associated
5922 // cards). We need these updates logged to update any
5923 // RSets.
5924 enqueue_discovered_references(n_workers);
5925
5926 if (G1DeferredRSUpdate) {
5927 redirty_logged_cards();
5928 }
5929 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5930 }
5931
5932 void G1CollectedHeap::free_region(HeapRegion* hr,
5933 FreeRegionList* free_list,
5934 bool par,
5935 bool locked) {
5936 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5937 assert(!hr->is_empty(), "the region should not be empty");
5938 assert(free_list != NULL, "pre-condition");
5939
5940 // Clear the card counts for this region.
5941 // Note: we only need to do this if the region is not young
5942 // (since we don't refine cards in young regions).
5943 if (!hr->is_young()) {
5944 _cg1r->hot_card_cache()->reset_card_counts(hr);
5945 }
5946 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5947 free_list->add_ordered(hr);
5948 }
5949
5950 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5951 FreeRegionList* free_list,
5952 bool par) {
5953 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5954 assert(free_list != NULL, "pre-condition");
5955
5956 size_t hr_capacity = hr->capacity();
5957 // We need to read this before we make the region non-humongous,
5958 // otherwise the information will be gone.
5959 uint last_index = hr->last_hc_index();
5960 hr->set_notHumongous();
5961 free_region(hr, free_list, par);
5962
5963 uint i = hr->hrs_index() + 1;
5964 while (i < last_index) {
5965 HeapRegion* curr_hr = region_at(i);
5966 assert(curr_hr->continuesHumongous(), "invariant");
5967 curr_hr->set_notHumongous();
5968 free_region(curr_hr, free_list, par);
5969 i += 1;
5970 }
5971 }
5972
5973 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5974 const HeapRegionSetCount& humongous_regions_removed) {
5975 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5976 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5977 _old_set.bulk_remove(old_regions_removed);
5978 _humongous_set.bulk_remove(humongous_regions_removed);
5979 }
5980
5981 }
5982
5983 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5984 assert(list != NULL, "list can't be null");
5985 if (!list->is_empty()) {
5986 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5987 _free_list.add_ordered(list);
5988 }
5989 }
5990
5991 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5992 assert(_summary_bytes_used >= bytes,
5993 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
5994 _summary_bytes_used, bytes));
5995 _summary_bytes_used -= bytes;
5996 }
5997
5998 class G1ParCleanupCTTask : public AbstractGangTask {
5999 G1SATBCardTableModRefBS* _ct_bs;
6000 G1CollectedHeap* _g1h;
6001 HeapRegion* volatile _su_head;
6002 public:
6003 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6004 G1CollectedHeap* g1h) :
6005 AbstractGangTask("G1 Par Cleanup CT Task"),
6006 _ct_bs(ct_bs), _g1h(g1h) { }
6007
6008 void work(uint worker_id) {
6009 HeapRegion* r;
6010 while (r = _g1h->pop_dirty_cards_region()) {
6011 clear_cards(r);
6012 }
6013 }
6014
6015 void clear_cards(HeapRegion* r) {
6016 // Cards of the survivors should have already been dirtied.
6017 if (!r->is_survivor()) {
6018 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6019 }
6020 }
6021 };
6022
6023 #ifndef PRODUCT
6024 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6025 G1CollectedHeap* _g1h;
6026 G1SATBCardTableModRefBS* _ct_bs;
6027 public:
6028 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6029 : _g1h(g1h), _ct_bs(ct_bs) { }
6030 virtual bool doHeapRegion(HeapRegion* r) {
6031 if (r->is_survivor()) {
6032 _g1h->verify_dirty_region(r);
6033 } else {
6034 _g1h->verify_not_dirty_region(r);
6035 }
6036 return false;
6037 }
6038 };
6039
6040 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6041 // All of the region should be clean.
6042 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6043 MemRegion mr(hr->bottom(), hr->end());
6044 ct_bs->verify_not_dirty_region(mr);
6045 }
6046
6047 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6048 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6049 // dirty allocated blocks as they allocate them. The thread that
6050 // retires each region and replaces it with a new one will do a
6051 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6052 // not dirty that area (one less thing to have to do while holding
6053 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6054 // is dirty.
6055 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6056 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6057 if (hr->is_young()) {
6058 ct_bs->verify_g1_young_region(mr);
6059 } else {
6060 ct_bs->verify_dirty_region(mr);
6061 }
6062 }
6063
6064 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6065 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6066 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6067 verify_dirty_region(hr);
6068 }
6069 }
6070
6071 void G1CollectedHeap::verify_dirty_young_regions() {
6072 verify_dirty_young_list(_young_list->first_region());
6073 }
6074 #endif
6075
6076 void G1CollectedHeap::cleanUpCardTable() {
6077 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6078 double start = os::elapsedTime();
6079
6080 {
6081 // Iterate over the dirty cards region list.
6082 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6083
6084 if (G1CollectedHeap::use_parallel_gc_threads()) {
6085 set_par_threads();
6086 workers()->run_task(&cleanup_task);
6087 set_par_threads(0);
6088 } else {
6089 while (_dirty_cards_region_list) {
6090 HeapRegion* r = _dirty_cards_region_list;
6091 cleanup_task.clear_cards(r);
6092 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6093 if (_dirty_cards_region_list == r) {
6094 // The last region.
6095 _dirty_cards_region_list = NULL;
6096 }
6097 r->set_next_dirty_cards_region(NULL);
6098 }
6099 }
6100 #ifndef PRODUCT
6101 if (G1VerifyCTCleanup || VerifyAfterGC) {
6102 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6103 heap_region_iterate(&cleanup_verifier);
6104 }
6105 #endif
6106 }
6107
6108 double elapsed = os::elapsedTime() - start;
6109 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6110 }
6111
6112 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6113 size_t pre_used = 0;
6114 FreeRegionList local_free_list("Local List for CSet Freeing");
6115
6116 double young_time_ms = 0.0;
6117 double non_young_time_ms = 0.0;
6118
6119 // Since the collection set is a superset of the the young list,
6120 // all we need to do to clear the young list is clear its
6121 // head and length, and unlink any young regions in the code below
6122 _young_list->clear();
6123
6124 G1CollectorPolicy* policy = g1_policy();
6125
6126 double start_sec = os::elapsedTime();
6127 bool non_young = true;
6128
6129 HeapRegion* cur = cs_head;
6130 int age_bound = -1;
6131 size_t rs_lengths = 0;
6132
6133 while (cur != NULL) {
6134 assert(!is_on_master_free_list(cur), "sanity");
6135 if (non_young) {
6136 if (cur->is_young()) {
6137 double end_sec = os::elapsedTime();
6138 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6139 non_young_time_ms += elapsed_ms;
6140
6141 start_sec = os::elapsedTime();
6142 non_young = false;
6143 }
6144 } else {
6145 if (!cur->is_young()) {
6146 double end_sec = os::elapsedTime();
6147 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6148 young_time_ms += elapsed_ms;
6149
6150 start_sec = os::elapsedTime();
6151 non_young = true;
6152 }
6153 }
6154
6155 rs_lengths += cur->rem_set()->occupied_locked();
6156
6157 HeapRegion* next = cur->next_in_collection_set();
6158 assert(cur->in_collection_set(), "bad CS");
6159 cur->set_next_in_collection_set(NULL);
6160 cur->set_in_collection_set(false);
6161
6162 if (cur->is_young()) {
6163 int index = cur->young_index_in_cset();
6164 assert(index != -1, "invariant");
6165 assert((uint) index < policy->young_cset_region_length(), "invariant");
6166 size_t words_survived = _surviving_young_words[index];
6167 cur->record_surv_words_in_group(words_survived);
6168
6169 // At this point the we have 'popped' cur from the collection set
6170 // (linked via next_in_collection_set()) but it is still in the
6171 // young list (linked via next_young_region()). Clear the
6172 // _next_young_region field.
6173 cur->set_next_young_region(NULL);
6174 } else {
6175 int index = cur->young_index_in_cset();
6176 assert(index == -1, "invariant");
6177 }
6178
6179 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6180 (!cur->is_young() && cur->young_index_in_cset() == -1),
6181 "invariant" );
6182
6183 if (!cur->evacuation_failed()) {
6184 MemRegion used_mr = cur->used_region();
6185
6186 // And the region is empty.
6187 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6188 pre_used += cur->used();
6189 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6190 } else {
6191 cur->uninstall_surv_rate_group();
6192 if (cur->is_young()) {
6193 cur->set_young_index_in_cset(-1);
6194 }
6195 cur->set_not_young();
6196 cur->set_evacuation_failed(false);
6197 // The region is now considered to be old.
6198 _old_set.add(cur);
6199 evacuation_info.increment_collectionset_used_after(cur->used());
6200 }
6201 cur = next;
6202 }
6203
6204 evacuation_info.set_regions_freed(local_free_list.length());
6205 policy->record_max_rs_lengths(rs_lengths);
6206 policy->cset_regions_freed();
6207
6208 double end_sec = os::elapsedTime();
6209 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6210
6211 if (non_young) {
6212 non_young_time_ms += elapsed_ms;
6213 } else {
6214 young_time_ms += elapsed_ms;
6215 }
6216
6217 prepend_to_freelist(&local_free_list);
6218 decrement_summary_bytes(pre_used);
6219 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6220 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6221 }
6222
6223 // This routine is similar to the above but does not record
6224 // any policy statistics or update free lists; we are abandoning
6225 // the current incremental collection set in preparation of a
6226 // full collection. After the full GC we will start to build up
6227 // the incremental collection set again.
6228 // This is only called when we're doing a full collection
6229 // and is immediately followed by the tearing down of the young list.
6230
6231 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6232 HeapRegion* cur = cs_head;
6233
6234 while (cur != NULL) {
6235 HeapRegion* next = cur->next_in_collection_set();
6236 assert(cur->in_collection_set(), "bad CS");
6237 cur->set_next_in_collection_set(NULL);
6238 cur->set_in_collection_set(false);
6239 cur->set_young_index_in_cset(-1);
6240 cur = next;
6241 }
6242 }
6243
6244 void G1CollectedHeap::set_free_regions_coming() {
6245 if (G1ConcRegionFreeingVerbose) {
6246 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6247 "setting free regions coming");
6248 }
6249
6250 assert(!free_regions_coming(), "pre-condition");
6251 _free_regions_coming = true;
6252 }
6253
6254 void G1CollectedHeap::reset_free_regions_coming() {
6255 assert(free_regions_coming(), "pre-condition");
6256
6257 {
6258 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6259 _free_regions_coming = false;
6260 SecondaryFreeList_lock->notify_all();
6261 }
6262
6263 if (G1ConcRegionFreeingVerbose) {
6264 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6265 "reset free regions coming");
6266 }
6267 }
6268
6269 void G1CollectedHeap::wait_while_free_regions_coming() {
6270 // Most of the time we won't have to wait, so let's do a quick test
6271 // first before we take the lock.
6272 if (!free_regions_coming()) {
6273 return;
6274 }
6275
6276 if (G1ConcRegionFreeingVerbose) {
6277 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6278 "waiting for free regions");
6279 }
6280
6281 {
6282 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6283 while (free_regions_coming()) {
6284 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6285 }
6286 }
6287
6288 if (G1ConcRegionFreeingVerbose) {
6289 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6290 "done waiting for free regions");
6291 }
6292 }
6293
6294 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6295 assert(heap_lock_held_for_gc(),
6296 "the heap lock should already be held by or for this thread");
6297 _young_list->push_region(hr);
6298 }
6299
6300 class NoYoungRegionsClosure: public HeapRegionClosure {
6301 private:
6302 bool _success;
6303 public:
6304 NoYoungRegionsClosure() : _success(true) { }
6305 bool doHeapRegion(HeapRegion* r) {
6306 if (r->is_young()) {
6307 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6308 r->bottom(), r->end());
6309 _success = false;
6310 }
6311 return false;
6312 }
6313 bool success() { return _success; }
6314 };
6315
6316 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6317 bool ret = _young_list->check_list_empty(check_sample);
6318
6319 if (check_heap) {
6320 NoYoungRegionsClosure closure;
6321 heap_region_iterate(&closure);
6322 ret = ret && closure.success();
6323 }
6324
6325 return ret;
6326 }
6327
6328 class TearDownRegionSetsClosure : public HeapRegionClosure {
6329 private:
6330 HeapRegionSet *_old_set;
6331
6332 public:
6333 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6334
6335 bool doHeapRegion(HeapRegion* r) {
6336 if (r->is_empty()) {
6337 // We ignore empty regions, we'll empty the free list afterwards
6338 } else if (r->is_young()) {
6339 // We ignore young regions, we'll empty the young list afterwards
6340 } else if (r->isHumongous()) {
6341 // We ignore humongous regions, we're not tearing down the
6342 // humongous region set
6343 } else {
6344 // The rest should be old
6345 _old_set->remove(r);
6346 }
6347 return false;
6348 }
6349
6350 ~TearDownRegionSetsClosure() {
6351 assert(_old_set->is_empty(), "post-condition");
6352 }
6353 };
6354
6355 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6356 assert_at_safepoint(true /* should_be_vm_thread */);
6357
6358 if (!free_list_only) {
6359 TearDownRegionSetsClosure cl(&_old_set);
6360 heap_region_iterate(&cl);
6361
6362 // Note that emptying the _young_list is postponed and instead done as
6363 // the first step when rebuilding the regions sets again. The reason for
6364 // this is that during a full GC string deduplication needs to know if
6365 // a collected region was young or old when the full GC was initiated.
6366 }
6367 _free_list.remove_all();
6368 }
6369
6370 class RebuildRegionSetsClosure : public HeapRegionClosure {
6371 private:
6372 bool _free_list_only;
6373 HeapRegionSet* _old_set;
6374 FreeRegionList* _free_list;
6375 size_t _total_used;
6376
6377 public:
6378 RebuildRegionSetsClosure(bool free_list_only,
6379 HeapRegionSet* old_set, FreeRegionList* free_list) :
6380 _free_list_only(free_list_only),
6381 _old_set(old_set), _free_list(free_list), _total_used(0) {
6382 assert(_free_list->is_empty(), "pre-condition");
6383 if (!free_list_only) {
6384 assert(_old_set->is_empty(), "pre-condition");
6385 }
6386 }
6387
6388 bool doHeapRegion(HeapRegion* r) {
6389 if (r->continuesHumongous()) {
6390 return false;
6391 }
6392
6393 if (r->is_empty()) {
6394 // Add free regions to the free list
6395 _free_list->add_as_tail(r);
6396 } else if (!_free_list_only) {
6397 assert(!r->is_young(), "we should not come across young regions");
6398
6399 if (r->isHumongous()) {
6400 // We ignore humongous regions, we left the humongous set unchanged
6401 } else {
6402 // The rest should be old, add them to the old set
6403 _old_set->add(r);
6404 }
6405 _total_used += r->used();
6406 }
6407
6408 return false;
6409 }
6410
6411 size_t total_used() {
6412 return _total_used;
6413 }
6414 };
6415
6416 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6417 assert_at_safepoint(true /* should_be_vm_thread */);
6418
6419 if (!free_list_only) {
6420 _young_list->empty_list();
6421 }
6422
6423 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6424 heap_region_iterate(&cl);
6425
6426 if (!free_list_only) {
6427 _summary_bytes_used = cl.total_used();
6428 }
6429 assert(_summary_bytes_used == recalculate_used(),
6430 err_msg("inconsistent _summary_bytes_used, "
6431 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6432 _summary_bytes_used, recalculate_used()));
6433 }
6434
6435 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6436 _refine_cte_cl->set_concurrent(concurrent);
6437 }
6438
6439 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6440 HeapRegion* hr = heap_region_containing(p);
6441 if (hr == NULL) {
6442 return false;
6443 } else {
6444 return hr->is_in(p);
6445 }
6446 }
6447
6448 // Methods for the mutator alloc region
6449
6450 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6451 bool force) {
6452 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6453 assert(!force || g1_policy()->can_expand_young_list(),
6454 "if force is true we should be able to expand the young list");
6455 bool young_list_full = g1_policy()->is_young_list_full();
6456 if (force || !young_list_full) {
6457 HeapRegion* new_alloc_region = new_region(word_size,
6458 false /* is_old */,
6459 false /* do_expand */);
6460 if (new_alloc_region != NULL) {
6461 set_region_short_lived_locked(new_alloc_region);
6462 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6463 return new_alloc_region;
6464 }
6465 }
6466 return NULL;
6467 }
6468
6469 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6470 size_t allocated_bytes) {
6471 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6472 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6473
6474 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6475 _summary_bytes_used += allocated_bytes;
6476 _hr_printer.retire(alloc_region);
6477 // We update the eden sizes here, when the region is retired,
6478 // instead of when it's allocated, since this is the point that its
6479 // used space has been recored in _summary_bytes_used.
6480 g1mm()->update_eden_size();
6481 }
6482
6483 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6484 bool force) {
6485 return _g1h->new_mutator_alloc_region(word_size, force);
6486 }
6487
6488 void G1CollectedHeap::set_par_threads() {
6489 // Don't change the number of workers. Use the value previously set
6490 // in the workgroup.
6491 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6492 uint n_workers = workers()->active_workers();
6493 assert(UseDynamicNumberOfGCThreads ||
6494 n_workers == workers()->total_workers(),
6495 "Otherwise should be using the total number of workers");
6496 if (n_workers == 0) {
6497 assert(false, "Should have been set in prior evacuation pause.");
6498 n_workers = ParallelGCThreads;
6499 workers()->set_active_workers(n_workers);
6500 }
6501 set_par_threads(n_workers);
6502 }
6503
6504 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6505 size_t allocated_bytes) {
6506 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6507 }
6508
6509 // Methods for the GC alloc regions
6510
6511 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6512 uint count,
6513 GCAllocPurpose ap) {
6514 assert(FreeList_lock->owned_by_self(), "pre-condition");
6515
6516 if (count < g1_policy()->max_regions(ap)) {
6517 bool survivor = (ap == GCAllocForSurvived);
6518 HeapRegion* new_alloc_region = new_region(word_size,
6519 !survivor,
6520 true /* do_expand */);
6521 if (new_alloc_region != NULL) {
6522 // We really only need to do this for old regions given that we
6523 // should never scan survivors. But it doesn't hurt to do it
6524 // for survivors too.
6525 new_alloc_region->set_saved_mark();
6526 if (survivor) {
6527 new_alloc_region->set_survivor();
6528 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6529 } else {
6530 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6531 }
6532 bool during_im = g1_policy()->during_initial_mark_pause();
6533 new_alloc_region->note_start_of_copying(during_im);
6534 return new_alloc_region;
6535 } else {
6536 g1_policy()->note_alloc_region_limit_reached(ap);
6537 }
6538 }
6539 return NULL;
6540 }
6541
6542 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6543 size_t allocated_bytes,
6544 GCAllocPurpose ap) {
6545 bool during_im = g1_policy()->during_initial_mark_pause();
6546 alloc_region->note_end_of_copying(during_im);
6547 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6548 if (ap == GCAllocForSurvived) {
6549 young_list()->add_survivor_region(alloc_region);
6550 } else {
6551 _old_set.add(alloc_region);
6552 }
6553 _hr_printer.retire(alloc_region);
6554 }
6555
6556 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6557 bool force) {
6558 assert(!force, "not supported for GC alloc regions");
6559 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6560 }
6561
6562 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6563 size_t allocated_bytes) {
6564 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6565 GCAllocForSurvived);
6566 }
6567
6568 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6569 bool force) {
6570 assert(!force, "not supported for GC alloc regions");
6571 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6572 }
6573
6574 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6575 size_t allocated_bytes) {
6576 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6577 GCAllocForTenured);
6578 }
6579 // Heap region set verification
6580
6581 class VerifyRegionListsClosure : public HeapRegionClosure {
6582 private:
6583 HeapRegionSet* _old_set;
6584 HeapRegionSet* _humongous_set;
6585 FreeRegionList* _free_list;
6586
6587 public:
6588 HeapRegionSetCount _old_count;
6589 HeapRegionSetCount _humongous_count;
6590 HeapRegionSetCount _free_count;
6591
6592 VerifyRegionListsClosure(HeapRegionSet* old_set,
6593 HeapRegionSet* humongous_set,
6594 FreeRegionList* free_list) :
6595 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6596 _old_count(), _humongous_count(), _free_count(){ }
6597
6598 bool doHeapRegion(HeapRegion* hr) {
6599 if (hr->continuesHumongous()) {
6600 return false;
6601 }
6602
6603 if (hr->is_young()) {
6604 // TODO
6605 } else if (hr->startsHumongous()) {
6606 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6607 _humongous_count.increment(1u, hr->capacity());
6608 } else if (hr->is_empty()) {
6609 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6610 _free_count.increment(1u, hr->capacity());
6611 } else {
6612 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6613 _old_count.increment(1u, hr->capacity());
6614 }
6615 return false;
6616 }
6617
6618 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6619 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6620 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6621 old_set->total_capacity_bytes(), _old_count.capacity()));
6622
6623 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6624 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6625 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6626
6627 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6628 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6629 free_list->total_capacity_bytes(), _free_count.capacity()));
6630 }
6631 };
6632
6633 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6634 HeapWord* bottom) {
6635 HeapWord* end = bottom + HeapRegion::GrainWords;
6636 MemRegion mr(bottom, end);
6637 assert(_g1_reserved.contains(mr), "invariant");
6638 // This might return NULL if the allocation fails
6639 return new HeapRegion(hrs_index, _bot_shared, mr);
6640 }
6641
6642 void G1CollectedHeap::verify_region_sets() {
6643 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6644
6645 // First, check the explicit lists.
6646 _free_list.verify_list();
6647 {
6648 // Given that a concurrent operation might be adding regions to
6649 // the secondary free list we have to take the lock before
6650 // verifying it.
6651 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6652 _secondary_free_list.verify_list();
6653 }
6654
6655 // If a concurrent region freeing operation is in progress it will
6656 // be difficult to correctly attributed any free regions we come
6657 // across to the correct free list given that they might belong to
6658 // one of several (free_list, secondary_free_list, any local lists,
6659 // etc.). So, if that's the case we will skip the rest of the
6660 // verification operation. Alternatively, waiting for the concurrent
6661 // operation to complete will have a non-trivial effect on the GC's
6662 // operation (no concurrent operation will last longer than the
6663 // interval between two calls to verification) and it might hide
6664 // any issues that we would like to catch during testing.
6665 if (free_regions_coming()) {
6666 return;
6667 }
6668
6669 // Make sure we append the secondary_free_list on the free_list so
6670 // that all free regions we will come across can be safely
6671 // attributed to the free_list.
6672 append_secondary_free_list_if_not_empty_with_lock();
6673
6674 // Finally, make sure that the region accounting in the lists is
6675 // consistent with what we see in the heap.
6676
6677 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6678 heap_region_iterate(&cl);
6679 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6680 }
6681
6682 // Optimized nmethod scanning
6683
6684 class RegisterNMethodOopClosure: public OopClosure {
6685 G1CollectedHeap* _g1h;
6686 nmethod* _nm;
6687
6688 template <class T> void do_oop_work(T* p) {
6689 T heap_oop = oopDesc::load_heap_oop(p);
6690 if (!oopDesc::is_null(heap_oop)) {
6691 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6692 HeapRegion* hr = _g1h->heap_region_containing(obj);
6693 assert(!hr->continuesHumongous(),
6694 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6695 " starting at "HR_FORMAT,
6696 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6697
6698 // HeapRegion::add_strong_code_root() avoids adding duplicate
6699 // entries but having duplicates is OK since we "mark" nmethods
6700 // as visited when we scan the strong code root lists during the GC.
6701 hr->add_strong_code_root(_nm);
6702 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6703 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6704 _nm, HR_FORMAT_PARAMS(hr)));
6705 }
6706 }
6707
6708 public:
6709 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6710 _g1h(g1h), _nm(nm) {}
6711
6712 void do_oop(oop* p) { do_oop_work(p); }
6713 void do_oop(narrowOop* p) { do_oop_work(p); }
6714 };
6715
6716 class UnregisterNMethodOopClosure: public OopClosure {
6717 G1CollectedHeap* _g1h;
6718 nmethod* _nm;
6719
6720 template <class T> void do_oop_work(T* p) {
6721 T heap_oop = oopDesc::load_heap_oop(p);
6722 if (!oopDesc::is_null(heap_oop)) {
6723 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6724 HeapRegion* hr = _g1h->heap_region_containing(obj);
6725 assert(!hr->continuesHumongous(),
6726 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6727 " starting at "HR_FORMAT,
6728 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6729
6730 hr->remove_strong_code_root(_nm);
6731 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6732 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6733 _nm, HR_FORMAT_PARAMS(hr)));
6734 }
6735 }
6736
6737 public:
6738 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6739 _g1h(g1h), _nm(nm) {}
6740
6741 void do_oop(oop* p) { do_oop_work(p); }
6742 void do_oop(narrowOop* p) { do_oop_work(p); }
6743 };
6744
6745 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6746 CollectedHeap::register_nmethod(nm);
6747
6748 guarantee(nm != NULL, "sanity");
6749 RegisterNMethodOopClosure reg_cl(this, nm);
6750 nm->oops_do(®_cl);
6751 }
6752
6753 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6754 CollectedHeap::unregister_nmethod(nm);
6755
6756 guarantee(nm != NULL, "sanity");
6757 UnregisterNMethodOopClosure reg_cl(this, nm);
6758 nm->oops_do(®_cl, true);
6759 }
6760
6761 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6762 public:
6763 bool doHeapRegion(HeapRegion *hr) {
6764 assert(!hr->isHumongous(),
6765 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6766 HR_FORMAT_PARAMS(hr)));
6767 hr->migrate_strong_code_roots();
6768 return false;
6769 }
6770 };
6771
6772 void G1CollectedHeap::migrate_strong_code_roots() {
6773 MigrateCodeRootsHeapRegionClosure cl;
6774 double migrate_start = os::elapsedTime();
6775 collection_set_iterate(&cl);
6776 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6777 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6778 }
6779
6780 void G1CollectedHeap::purge_code_root_memory() {
6781 double purge_start = os::elapsedTime();
6782 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6783 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6784 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6785 }
6786
6787 // Mark all the code roots that point into regions *not* in the
6788 // collection set.
6789 //
6790 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6791 // walking the the code roots lists of regions not in the collection
6792 // set. Suppose we have an nmethod (M) that points to objects in two
6793 // separate regions - one in the collection set (R1) and one not (R2).
6794 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6795 // nmethod M when walking the code roots for R1. When we come to scan
6796 // the code roots for R2, we would see that M is already marked and it
6797 // would be skipped and the objects in R2 that are referenced from M
6798 // would not be evacuated.
6799
6800 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6801
6802 class MarkStrongCodeRootOopClosure: public OopClosure {
6803 ConcurrentMark* _cm;
6804 HeapRegion* _hr;
6805 uint _worker_id;
6806
6807 template <class T> void do_oop_work(T* p) {
6808 T heap_oop = oopDesc::load_heap_oop(p);
6809 if (!oopDesc::is_null(heap_oop)) {
6810 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6811 // Only mark objects in the region (which is assumed
6812 // to be not in the collection set).
6813 if (_hr->is_in(obj)) {
6814 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6815 }
6816 }
6817 }
6818
6819 public:
6820 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6821 _cm(cm), _hr(hr), _worker_id(worker_id) {
6822 assert(!_hr->in_collection_set(), "sanity");
6823 }
6824
6825 void do_oop(narrowOop* p) { do_oop_work(p); }
6826 void do_oop(oop* p) { do_oop_work(p); }
6827 };
6828
6829 MarkStrongCodeRootOopClosure _oop_cl;
6830
6831 public:
6832 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6833 _oop_cl(cm, hr, worker_id) {}
6834
6835 void do_code_blob(CodeBlob* cb) {
6836 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6837 if (nm != NULL) {
6838 nm->oops_do(&_oop_cl);
6839 }
6840 }
6841 };
6842
6843 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6844 G1CollectedHeap* _g1h;
6845 uint _worker_id;
6846
6847 public:
6848 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6849 _g1h(g1h), _worker_id(worker_id) {}
6850
6851 bool doHeapRegion(HeapRegion *hr) {
6852 HeapRegionRemSet* hrrs = hr->rem_set();
6853 if (hr->continuesHumongous()) {
6854 // Code roots should never be attached to a continuation of a humongous region
6855 assert(hrrs->strong_code_roots_list_length() == 0,
6856 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6857 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6858 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6859 hrrs->strong_code_roots_list_length()));
6860 return false;
6861 }
6862
6863 if (hr->in_collection_set()) {
6864 // Don't mark code roots into regions in the collection set here.
6865 // They will be marked when we scan them.
6866 return false;
6867 }
6868
6869 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6870 hr->strong_code_roots_do(&cb_cl);
6871 return false;
6872 }
6873 };
6874
6875 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6876 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6877 if (G1CollectedHeap::use_parallel_gc_threads()) {
6878 heap_region_par_iterate_chunked(&cl,
6879 worker_id,
6880 workers()->active_workers(),
6881 HeapRegion::ParMarkRootClaimValue);
6882 } else {
6883 heap_region_iterate(&cl);
6884 }
6885 }
6886
6887 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6888 G1CollectedHeap* _g1h;
6889
6890 public:
6891 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6892 _g1h(g1h) {}
6893
6894 void do_code_blob(CodeBlob* cb) {
6895 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6896 if (nm == NULL) {
6897 return;
6898 }
6899
6900 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6901 _g1h->register_nmethod(nm);
6902 }
6903 }
6904 };
6905
6906 void G1CollectedHeap::rebuild_strong_code_roots() {
6907 RebuildStrongCodeRootClosure blob_cl(this);
6908 CodeCache::blobs_do(&blob_cl);
6909 }