1 /*
2 * Copyright (c) 2001, 2013, 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/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
35 #include "gc_implementation/g1/g1EvacFailure.hpp"
36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
37 #include "gc_implementation/g1/g1Log.hpp"
38 #include "gc_implementation/g1/g1MarkSweep.hpp"
39 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
40 #include "gc_implementation/g1/g1RemSet.inline.hpp"
41 #include "gc_implementation/g1/g1YCTypes.hpp"
42 #include "gc_implementation/g1/heapRegion.inline.hpp"
43 #include "gc_implementation/g1/heapRegionRemSet.hpp"
44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
45 #include "gc_implementation/g1/vm_operations_g1.hpp"
46 #include "gc_implementation/shared/gcHeapSummary.hpp"
47 #include "gc_implementation/shared/gcTimer.hpp"
48 #include "gc_implementation/shared/gcTrace.hpp"
49 #include "gc_implementation/shared/gcTraceTime.hpp"
50 #include "gc_implementation/shared/isGCActiveMark.hpp"
51 #include "memory/gcLocker.inline.hpp"
52 #include "memory/genOopClosures.inline.hpp"
53 #include "memory/generationSpec.hpp"
54 #include "memory/referenceProcessor.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "oops/oop.pcgc.inline.hpp"
57 #include "runtime/vmThread.hpp"
58
59 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
60
61 // turn it on so that the contents of the young list (scan-only /
62 // to-be-collected) are printed at "strategic" points before / during
63 // / after the collection --- this is useful for debugging
64 #define YOUNG_LIST_VERBOSE 0
65 // CURRENT STATUS
66 // This file is under construction. Search for "FIXME".
67
68 // INVARIANTS/NOTES
69 //
70 // All allocation activity covered by the G1CollectedHeap interface is
71 // serialized by acquiring the HeapLock. This happens in mem_allocate
72 // and allocate_new_tlab, which are the "entry" points to the
73 // allocation code from the rest of the JVM. (Note that this does not
74 // apply to TLAB allocation, which is not part of this interface: it
75 // is done by clients of this interface.)
76
77 // Notes on implementation of parallelism in different tasks.
78 //
79 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
80 // The number of GC workers is passed to heap_region_par_iterate_chunked().
81 // It does use run_task() which sets _n_workers in the task.
82 // G1ParTask executes g1_process_strong_roots() ->
83 // SharedHeap::process_strong_roots() which calls eventually to
84 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
85 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
86 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
87 //
88
89 // Local to this file.
90
91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
92 SuspendibleThreadSet* _sts;
93 G1RemSet* _g1rs;
94 bool _concurrent;
95 public:
96 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
97 G1RemSet* g1rs) :
98 _sts(sts), _g1rs(g1rs), _concurrent(true)
99 {}
100 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
101 bool oops_into_cset;
102 if (_concurrent) {
103 oops_into_cset = _g1rs->refine_card_without_check(card_ptr, worker_i, false);
104 } else {
105 assert(SafepointSynchronize::is_at_safepoint(), "only safe if at safepoint");
106 oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
107 }
108 // This path is executed by the concurrent refine or mutator threads,
109 // concurrently, and so we do not care if card_ptr contains references
110 // that point into the collection set.
111 assert(!oops_into_cset, "should be");
112
113 if (_concurrent && _sts->should_yield()) {
114 // Caller will actually yield.
115 return false;
116 }
117 // Otherwise, we finished successfully; return true.
118 return true;
119 }
120 void set_concurrent(bool b) { _concurrent = b; }
121 };
122
123 class TransferDirtyCardsToRefinementClosure: public CardTableEntryClosure {
124 public:
125 class FlushTransferClosure: public VoidClosure {
126 friend class TransferDirtyCardsToRefinementClosure;
127 TransferDirtyCardsToRefinementClosure* _cl;
128 public:
129 void do_void() {
130 assert(_cl != NULL, "should be inited");
131 _cl->_dcq.flush();
132 }
133 };
134
135 private:
136 FlushTransferClosure _flush_cl;
137 DirtyCardQueue _dcq;
138 public:
139 TransferDirtyCardsToRefinementClosure(DirtyCardQueueSet& target) : _dcq(&target) {
140 _flush_cl._cl = this;
141 }
142
143 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
144 assert(SafepointSynchronize::is_at_safepoint(), "only safe to transfer/clean cards at safepoint");
145 assert(!G1CollectedHeap::heap()->is_gc_active(), "should not get here if doing a gc");
146 _dcq.enqueue(card_ptr);
147 *card_ptr = CardTableModRefBS::clean_card_val();
148 return true;
149 }
150
151 public:
152 FlushTransferClosure* flush_cl() { return &_flush_cl; }
153 };
154
155
156
157 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
158 int _calls;
159 G1CollectedHeap* _g1h;
160 CardTableModRefBS* _ctbs;
161 int _histo[256];
162 public:
163 ClearLoggedCardTableEntryClosure() :
164 _calls(0)
165 {
166 _g1h = G1CollectedHeap::heap();
167 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
168 for (int i = 0; i < 256; i++) _histo[i] = 0;
169 }
170 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
171 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
172 _calls++;
173 unsigned char* ujb = (unsigned char*)card_ptr;
174 int ind = (int)(*ujb);
175 _histo[ind]++;
176 *card_ptr = -1;
177 }
178 return true;
179 }
180 int calls() { return _calls; }
181 void print_histo() {
182 gclog_or_tty->print_cr("Card table value histogram:");
183 for (int i = 0; i < 256; i++) {
184 if (_histo[i] != 0) {
185 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
186 }
187 }
188 }
189 };
190
191 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
192 int _calls;
193 G1CollectedHeap* _g1h;
194 CardTableModRefBS* _ctbs;
195 public:
196 RedirtyLoggedCardTableEntryClosure() :
197 _calls(0)
198 {
199 _g1h = G1CollectedHeap::heap();
200 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
201 }
202 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
203 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
204 _calls++;
205 *card_ptr = 0;
206 }
207 return true;
208 }
209 int calls() { return _calls; }
210 };
211
212 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
213 public:
214 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
215 *card_ptr = CardTableModRefBS::dirty_card_val();
216 return true;
217 }
218 };
219
220 YoungList::YoungList(G1CollectedHeap* g1h) :
221 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
222 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
223 guarantee(check_list_empty(false), "just making sure...");
224 }
225
226 void YoungList::push_region(HeapRegion *hr) {
227 assert(!hr->is_young(), "should not already be young");
228 assert(hr->get_next_young_region() == NULL, "cause it should!");
229
230 hr->set_next_young_region(_head);
231 _head = hr;
232
233 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
234 ++_length;
235 }
236
237 void YoungList::add_survivor_region(HeapRegion* hr) {
238 assert(hr->is_survivor(), "should be flagged as survivor region");
239 assert(hr->get_next_young_region() == NULL, "cause it should!");
240
241 hr->set_next_young_region(_survivor_head);
242 if (_survivor_head == NULL) {
243 _survivor_tail = hr;
244 }
245 _survivor_head = hr;
246 ++_survivor_length;
247 }
248
249 void YoungList::empty_list(HeapRegion* list) {
250 while (list != NULL) {
251 HeapRegion* next = list->get_next_young_region();
252 list->set_next_young_region(NULL);
253 list->uninstall_surv_rate_group();
254 list->set_not_young();
255 list = next;
256 }
257 }
258
259 void YoungList::empty_list() {
260 assert(check_list_well_formed(), "young list should be well formed");
261
262 empty_list(_head);
263 _head = NULL;
264 _length = 0;
265
266 empty_list(_survivor_head);
267 _survivor_head = NULL;
268 _survivor_tail = NULL;
269 _survivor_length = 0;
270
271 _last_sampled_rs_lengths = 0;
272
273 assert(check_list_empty(false), "just making sure...");
274 }
275
276 bool YoungList::check_list_well_formed() {
277 bool ret = true;
278
279 uint length = 0;
280 HeapRegion* curr = _head;
281 HeapRegion* last = NULL;
282 while (curr != NULL) {
283 if (!curr->is_young()) {
284 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
285 "incorrectly tagged (y: %d, surv: %d)",
286 curr->bottom(), curr->end(),
287 curr->is_young(), curr->is_survivor());
288 ret = false;
289 }
290 ++length;
291 last = curr;
292 curr = curr->get_next_young_region();
293 }
294 ret = ret && (length == _length);
295
296 if (!ret) {
297 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
298 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
299 length, _length);
300 }
301
302 return ret;
303 }
304
305 bool YoungList::check_list_empty(bool check_sample) {
306 bool ret = true;
307
308 if (_length != 0) {
309 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
310 _length);
311 ret = false;
312 }
313 if (check_sample && _last_sampled_rs_lengths != 0) {
314 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
315 ret = false;
316 }
317 if (_head != NULL) {
318 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
319 ret = false;
320 }
321 if (!ret) {
322 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
323 }
324
325 return ret;
326 }
327
328 void
329 YoungList::rs_length_sampling_init() {
330 _sampled_rs_lengths = 0;
331 _curr = _head;
332 }
333
334 bool
335 YoungList::rs_length_sampling_more() {
336 return _curr != NULL;
337 }
338
339 void
340 YoungList::rs_length_sampling_next() {
341 assert( _curr != NULL, "invariant" );
342 size_t rs_length = _curr->rem_set()->occupied();
343
344 _sampled_rs_lengths += rs_length;
345
346 // The current region may not yet have been added to the
347 // incremental collection set (it gets added when it is
348 // retired as the current allocation region).
349 if (_curr->in_collection_set()) {
350 // Update the collection set policy information for this region
351 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
352 }
353
354 _curr = _curr->get_next_young_region();
355 if (_curr == NULL) {
356 _last_sampled_rs_lengths = _sampled_rs_lengths;
357 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
358 }
359 }
360
361 void
362 YoungList::reset_auxilary_lists() {
363 guarantee( is_empty(), "young list should be empty" );
364 assert(check_list_well_formed(), "young list should be well formed");
365
366 // Add survivor regions to SurvRateGroup.
367 _g1h->g1_policy()->note_start_adding_survivor_regions();
368 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
369
370 int young_index_in_cset = 0;
371 for (HeapRegion* curr = _survivor_head;
372 curr != NULL;
373 curr = curr->get_next_young_region()) {
374 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
375
376 // The region is a non-empty survivor so let's add it to
377 // the incremental collection set for the next evacuation
378 // pause.
379 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
380 young_index_in_cset += 1;
381 }
382 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
383 _g1h->g1_policy()->note_stop_adding_survivor_regions();
384
385 _head = _survivor_head;
386 _length = _survivor_length;
387 if (_survivor_head != NULL) {
388 assert(_survivor_tail != NULL, "cause it shouldn't be");
389 assert(_survivor_length > 0, "invariant");
390 _survivor_tail->set_next_young_region(NULL);
391 }
392
393 // Don't clear the survivor list handles until the start of
394 // the next evacuation pause - we need it in order to re-tag
395 // the survivor regions from this evacuation pause as 'young'
396 // at the start of the next.
397
398 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
399
400 assert(check_list_well_formed(), "young list should be well formed");
401 }
402
403 void YoungList::print() {
404 HeapRegion* lists[] = {_head, _survivor_head};
405 const char* names[] = {"YOUNG", "SURVIVOR"};
406
407 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
408 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
409 HeapRegion *curr = lists[list];
410 if (curr == NULL)
411 gclog_or_tty->print_cr(" empty");
412 while (curr != NULL) {
413 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
414 HR_FORMAT_PARAMS(curr),
415 curr->prev_top_at_mark_start(),
416 curr->next_top_at_mark_start(),
417 curr->age_in_surv_rate_group_cond());
418 curr = curr->get_next_young_region();
419 }
420 }
421
422 gclog_or_tty->print_cr("");
423 }
424
425 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
426 {
427 // Claim the right to put the region on the dirty cards region list
428 // by installing a self pointer.
429 HeapRegion* next = hr->get_next_dirty_cards_region();
430 if (next == NULL) {
431 HeapRegion* res = (HeapRegion*)
432 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
433 NULL);
434 if (res == NULL) {
435 HeapRegion* head;
436 do {
437 // Put the region to the dirty cards region list.
438 head = _dirty_cards_region_list;
439 next = (HeapRegion*)
440 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
441 if (next == head) {
442 assert(hr->get_next_dirty_cards_region() == hr,
443 "hr->get_next_dirty_cards_region() != hr");
444 if (next == NULL) {
445 // The last region in the list points to itself.
446 hr->set_next_dirty_cards_region(hr);
447 } else {
448 hr->set_next_dirty_cards_region(next);
449 }
450 }
451 } while (next != head);
452 }
453 }
454 }
455
456 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
457 {
458 HeapRegion* head;
459 HeapRegion* hr;
460 do {
461 head = _dirty_cards_region_list;
462 if (head == NULL) {
463 return NULL;
464 }
465 HeapRegion* new_head = head->get_next_dirty_cards_region();
466 if (head == new_head) {
467 // The last region.
468 new_head = NULL;
469 }
470 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
471 head);
472 } while (hr != head);
473 assert(hr != NULL, "invariant");
474 hr->set_next_dirty_cards_region(NULL);
475 return hr;
476 }
477
478 void G1CollectedHeap::stop_conc_gc_threads() {
479 _cg1r->stop();
480 _cmThread->stop();
481 }
482
483 #ifdef ASSERT
484 // A region is added to the collection set as it is retired
485 // so an address p can point to a region which will be in the
486 // collection set but has not yet been retired. This method
487 // therefore is only accurate during a GC pause after all
488 // regions have been retired. It is used for debugging
489 // to check if an nmethod has references to objects that can
490 // be move during a partial collection. Though it can be
491 // inaccurate, it is sufficient for G1 because the conservative
492 // implementation of is_scavengable() for G1 will indicate that
493 // all nmethods must be scanned during a partial collection.
494 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
495 HeapRegion* hr = heap_region_containing(p);
496 return hr != NULL && hr->in_collection_set();
497 }
498 #endif
499
500 // Returns true if the reference points to an object that
501 // can move in an incremental collection.
502 bool G1CollectedHeap::is_scavengable(const void* p) {
503 G1CollectedHeap* g1h = G1CollectedHeap::heap();
504 G1CollectorPolicy* g1p = g1h->g1_policy();
505 HeapRegion* hr = heap_region_containing(p);
506 if (hr == NULL) {
507 // null
508 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
509 return false;
510 } else {
511 return !hr->isHumongous();
512 }
513 }
514
515 void G1CollectedHeap::check_ct_logs_at_safepoint() {
516 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
517 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
518
519 // Count the dirty cards at the start.
520 CountNonCleanMemRegionClosure count1(this);
521 ct_bs->mod_card_iterate(&count1);
522 int orig_count = count1.n();
523
524 // First clear the logged cards.
525 ClearLoggedCardTableEntryClosure clear;
526 dcqs.set_closure(&clear);
527 dcqs.apply_closure_to_all_completed_buffers();
528 dcqs.iterate_closure_all_threads(false);
529 clear.print_histo();
530
531 // Now ensure that there's no dirty cards.
532 CountNonCleanMemRegionClosure count2(this);
533 ct_bs->mod_card_iterate(&count2);
534 if (count2.n() != 0) {
535 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
536 count2.n(), orig_count);
537 }
538 guarantee(count2.n() == 0, "Card table should be clean.");
539
540 RedirtyLoggedCardTableEntryClosure redirty;
541 JavaThread::dirty_card_queue_set().set_closure(&redirty);
542 dcqs.apply_closure_to_all_completed_buffers();
543 dcqs.iterate_closure_all_threads(false);
544 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
545 clear.calls(), orig_count);
546 guarantee(redirty.calls() == clear.calls(),
547 "Or else mechanism is broken.");
548
549 CountNonCleanMemRegionClosure count3(this);
550 ct_bs->mod_card_iterate(&count3);
551 if (count3.n() != orig_count) {
552 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
553 orig_count, count3.n());
554 guarantee(count3.n() >= orig_count, "Should have restored them all.");
555 }
556
557 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
558 }
559
560 // Private class members.
561
562 G1CollectedHeap* G1CollectedHeap::_g1h;
563
564 // Private methods.
565
566 HeapRegion*
567 G1CollectedHeap::new_region_try_secondary_free_list() {
568 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
569 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
570 if (!_secondary_free_list.is_empty()) {
571 if (G1ConcRegionFreeingVerbose) {
572 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
573 "secondary_free_list has %u entries",
574 _secondary_free_list.length());
575 }
576 // It looks as if there are free regions available on the
577 // secondary_free_list. Let's move them to the free_list and try
578 // again to allocate from it.
579 append_secondary_free_list();
580
581 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
582 "empty we should have moved at least one entry to the free_list");
583 HeapRegion* res = _free_list.remove_head();
584 if (G1ConcRegionFreeingVerbose) {
585 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
586 "allocated "HR_FORMAT" from secondary_free_list",
587 HR_FORMAT_PARAMS(res));
588 }
589 return res;
590 }
591
592 // Wait here until we get notified either when (a) there are no
593 // more free regions coming or (b) some regions have been moved on
594 // the secondary_free_list.
595 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
596 }
597
598 if (G1ConcRegionFreeingVerbose) {
599 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
600 "could not allocate from secondary_free_list");
601 }
602 return NULL;
603 }
604
605 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
606 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
607 "the only time we use this to allocate a humongous region is "
608 "when we are allocating a single humongous region");
609
610 HeapRegion* res;
611 if (G1StressConcRegionFreeing) {
612 if (!_secondary_free_list.is_empty()) {
613 if (G1ConcRegionFreeingVerbose) {
614 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
615 "forced to look at the secondary_free_list");
616 }
617 res = new_region_try_secondary_free_list();
618 if (res != NULL) {
619 return res;
620 }
621 }
622 }
623 res = _free_list.remove_head_or_null();
624 if (res == NULL) {
625 if (G1ConcRegionFreeingVerbose) {
626 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
627 "res == NULL, trying the secondary_free_list");
628 }
629 res = new_region_try_secondary_free_list();
630 }
631 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
632 // Currently, only attempts to allocate GC alloc regions set
633 // do_expand to true. So, we should only reach here during a
634 // safepoint. If this assumption changes we might have to
635 // reconsider the use of _expand_heap_after_alloc_failure.
636 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
637
638 ergo_verbose1(ErgoHeapSizing,
639 "attempt heap expansion",
640 ergo_format_reason("region allocation request failed")
641 ergo_format_byte("allocation request"),
642 word_size * HeapWordSize);
643 if (expand(word_size * HeapWordSize)) {
644 // Given that expand() succeeded in expanding the heap, and we
645 // always expand the heap by an amount aligned to the heap
646 // region size, the free list should in theory not be empty. So
647 // it would probably be OK to use remove_head(). But the extra
648 // check for NULL is unlikely to be a performance issue here (we
649 // just expanded the heap!) so let's just be conservative and
650 // use remove_head_or_null().
651 res = _free_list.remove_head_or_null();
652 } else {
653 _expand_heap_after_alloc_failure = false;
654 }
655 }
656 return res;
657 }
658
659 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
660 size_t word_size) {
661 assert(isHumongous(word_size), "word_size should be humongous");
662 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
663
664 uint first = G1_NULL_HRS_INDEX;
665 if (num_regions == 1) {
666 // Only one region to allocate, no need to go through the slower
667 // path. The caller will attempt the expansion if this fails, so
668 // let's not try to expand here too.
669 HeapRegion* hr = new_region(word_size, false /* do_expand */);
670 if (hr != NULL) {
671 first = hr->hrs_index();
672 } else {
673 first = G1_NULL_HRS_INDEX;
674 }
675 } else {
676 // We can't allocate humongous regions while cleanupComplete() is
677 // running, since some of the regions we find to be empty might not
678 // yet be added to the free list and it is not straightforward to
679 // know which list they are on so that we can remove them. Note
680 // that we only need to do this if we need to allocate more than
681 // one region to satisfy the current humongous allocation
682 // request. If we are only allocating one region we use the common
683 // region allocation code (see above).
684 wait_while_free_regions_coming();
685 append_secondary_free_list_if_not_empty_with_lock();
686
687 if (free_regions() >= num_regions) {
688 first = _hrs.find_contiguous(num_regions);
689 if (first != G1_NULL_HRS_INDEX) {
690 for (uint i = first; i < first + num_regions; ++i) {
691 HeapRegion* hr = region_at(i);
692 assert(hr->is_empty(), "sanity");
693 assert(is_on_master_free_list(hr), "sanity");
694 hr->set_pending_removal(true);
695 }
696 _free_list.remove_all_pending(num_regions);
697 }
698 }
699 }
700 return first;
701 }
702
703 HeapWord*
704 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
705 uint num_regions,
706 size_t word_size) {
707 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
708 assert(isHumongous(word_size), "word_size should be humongous");
709 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
710
711 // Index of last region in the series + 1.
712 uint last = first + num_regions;
713
714 // We need to initialize the region(s) we just discovered. This is
715 // a bit tricky given that it can happen concurrently with
716 // refinement threads refining cards on these regions and
717 // potentially wanting to refine the BOT as they are scanning
718 // those cards (this can happen shortly after a cleanup; see CR
719 // 6991377). So we have to set up the region(s) carefully and in
720 // a specific order.
721
722 // The word size sum of all the regions we will allocate.
723 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
724 assert(word_size <= word_size_sum, "sanity");
725
726 // This will be the "starts humongous" region.
727 HeapRegion* first_hr = region_at(first);
728 // The header of the new object will be placed at the bottom of
729 // the first region.
730 HeapWord* new_obj = first_hr->bottom();
731 // This will be the new end of the first region in the series that
732 // should also match the end of the last region in the series.
733 HeapWord* new_end = new_obj + word_size_sum;
734 // This will be the new top of the first region that will reflect
735 // this allocation.
736 HeapWord* new_top = new_obj + word_size;
737
738 // First, we need to zero the header of the space that we will be
739 // allocating. When we update top further down, some refinement
740 // threads might try to scan the region. By zeroing the header we
741 // ensure that any thread that will try to scan the region will
742 // come across the zero klass word and bail out.
743 //
744 // NOTE: It would not have been correct to have used
745 // CollectedHeap::fill_with_object() and make the space look like
746 // an int array. The thread that is doing the allocation will
747 // later update the object header to a potentially different array
748 // type and, for a very short period of time, the klass and length
749 // fields will be inconsistent. This could cause a refinement
750 // thread to calculate the object size incorrectly.
751 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
752
753 // We will set up the first region as "starts humongous". This
754 // will also update the BOT covering all the regions to reflect
755 // that there is a single object that starts at the bottom of the
756 // first region.
757 first_hr->set_startsHumongous(new_top, new_end);
758
759 // Then, if there are any, we will set up the "continues
760 // humongous" regions.
761 HeapRegion* hr = NULL;
762 for (uint i = first + 1; i < last; ++i) {
763 hr = region_at(i);
764 hr->set_continuesHumongous(first_hr);
765 }
766 // If we have "continues humongous" regions (hr != NULL), then the
767 // end of the last one should match new_end.
768 assert(hr == NULL || hr->end() == new_end, "sanity");
769
770 // Up to this point no concurrent thread would have been able to
771 // do any scanning on any region in this series. All the top
772 // fields still point to bottom, so the intersection between
773 // [bottom,top] and [card_start,card_end] will be empty. Before we
774 // update the top fields, we'll do a storestore to make sure that
775 // no thread sees the update to top before the zeroing of the
776 // object header and the BOT initialization.
777 OrderAccess::storestore();
778
779 // Now that the BOT and the object header have been initialized,
780 // we can update top of the "starts humongous" region.
781 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
782 "new_top should be in this region");
783 first_hr->set_top(new_top);
784 if (_hr_printer.is_active()) {
785 HeapWord* bottom = first_hr->bottom();
786 HeapWord* end = first_hr->orig_end();
787 if ((first + 1) == last) {
788 // the series has a single humongous region
789 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
790 } else {
791 // the series has more than one humongous regions
792 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
793 }
794 }
795
796 // Now, we will update the top fields of the "continues humongous"
797 // regions. The reason we need to do this is that, otherwise,
798 // these regions would look empty and this will confuse parts of
799 // G1. For example, the code that looks for a consecutive number
800 // of empty regions will consider them empty and try to
801 // re-allocate them. We can extend is_empty() to also include
802 // !continuesHumongous(), but it is easier to just update the top
803 // fields here. The way we set top for all regions (i.e., top ==
804 // end for all regions but the last one, top == new_top for the
805 // last one) is actually used when we will free up the humongous
806 // region in free_humongous_region().
807 hr = NULL;
808 for (uint i = first + 1; i < last; ++i) {
809 hr = region_at(i);
810 if ((i + 1) == last) {
811 // last continues humongous region
812 assert(hr->bottom() < new_top && new_top <= hr->end(),
813 "new_top should fall on this region");
814 hr->set_top(new_top);
815 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
816 } else {
817 // not last one
818 assert(new_top > hr->end(), "new_top should be above this region");
819 hr->set_top(hr->end());
820 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
821 }
822 }
823 // If we have continues humongous regions (hr != NULL), then the
824 // end of the last one should match new_end and its top should
825 // match new_top.
826 assert(hr == NULL ||
827 (hr->end() == new_end && hr->top() == new_top), "sanity");
828
829 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
830 _summary_bytes_used += first_hr->used();
831 _humongous_set.add(first_hr);
832
833 return new_obj;
834 }
835
836 // If could fit into free regions w/o expansion, try.
837 // Otherwise, if can expand, do so.
838 // Otherwise, if using ex regions might help, try with ex given back.
839 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
840 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
841
842 verify_region_sets_optional();
843
844 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
845 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
846 uint x_num = expansion_regions();
847 uint fs = _hrs.free_suffix();
848 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
849 if (first == G1_NULL_HRS_INDEX) {
850 // The only thing we can do now is attempt expansion.
851 if (fs + x_num >= num_regions) {
852 // If the number of regions we're trying to allocate for this
853 // object is at most the number of regions in the free suffix,
854 // then the call to humongous_obj_allocate_find_first() above
855 // should have succeeded and we wouldn't be here.
856 //
857 // We should only be trying to expand when the free suffix is
858 // not sufficient for the object _and_ we have some expansion
859 // room available.
860 assert(num_regions > fs, "earlier allocation should have succeeded");
861
862 ergo_verbose1(ErgoHeapSizing,
863 "attempt heap expansion",
864 ergo_format_reason("humongous allocation request failed")
865 ergo_format_byte("allocation request"),
866 word_size * HeapWordSize);
867 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
868 // Even though the heap was expanded, it might not have
869 // reached the desired size. So, we cannot assume that the
870 // allocation will succeed.
871 first = humongous_obj_allocate_find_first(num_regions, word_size);
872 }
873 }
874 }
875
876 HeapWord* result = NULL;
877 if (first != G1_NULL_HRS_INDEX) {
878 result =
879 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
880 assert(result != NULL, "it should always return a valid result");
881
882 // A successful humongous object allocation changes the used space
883 // information of the old generation so we need to recalculate the
884 // sizes and update the jstat counters here.
885 g1mm()->update_sizes();
886 }
887
888 verify_region_sets_optional();
889
890 return result;
891 }
892
893 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
894 assert_heap_not_locked_and_not_at_safepoint();
895 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
896
897 unsigned int dummy_gc_count_before;
898 int dummy_gclocker_retry_count = 0;
899 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
900 }
901
902 HeapWord*
903 G1CollectedHeap::mem_allocate(size_t word_size,
904 bool* gc_overhead_limit_was_exceeded) {
905 assert_heap_not_locked_and_not_at_safepoint();
906
907 // Loop until the allocation is satisfied, or unsatisfied after GC.
908 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
909 unsigned int gc_count_before;
910
911 HeapWord* result = NULL;
912 if (!isHumongous(word_size)) {
913 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
914 } else {
915 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
916 }
917 if (result != NULL) {
918 return result;
919 }
920
921 // Create the garbage collection operation...
922 VM_G1CollectForAllocation op(gc_count_before, word_size);
923 // ...and get the VM thread to execute it.
924 VMThread::execute(&op);
925
926 if (op.prologue_succeeded() && op.pause_succeeded()) {
927 // If the operation was successful we'll return the result even
928 // if it is NULL. If the allocation attempt failed immediately
929 // after a Full GC, it's unlikely we'll be able to allocate now.
930 HeapWord* result = op.result();
931 if (result != NULL && !isHumongous(word_size)) {
932 // Allocations that take place on VM operations do not do any
933 // card dirtying and we have to do it here. We only have to do
934 // this for non-humongous allocations, though.
935 dirty_young_block(result, word_size);
936 }
937 return result;
938 } else {
939 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
940 return NULL;
941 }
942 assert(op.result() == NULL,
943 "the result should be NULL if the VM op did not succeed");
944 }
945
946 // Give a warning if we seem to be looping forever.
947 if ((QueuedAllocationWarningCount > 0) &&
948 (try_count % QueuedAllocationWarningCount == 0)) {
949 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
950 }
951 }
952
953 ShouldNotReachHere();
954 return NULL;
955 }
956
957 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
958 unsigned int *gc_count_before_ret,
959 int* gclocker_retry_count_ret) {
960 // Make sure you read the note in attempt_allocation_humongous().
961
962 assert_heap_not_locked_and_not_at_safepoint();
963 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
964 "be called for humongous allocation requests");
965
966 // We should only get here after the first-level allocation attempt
967 // (attempt_allocation()) failed to allocate.
968
969 // We will loop until a) we manage to successfully perform the
970 // allocation or b) we successfully schedule a collection which
971 // fails to perform the allocation. b) is the only case when we'll
972 // return NULL.
973 HeapWord* result = NULL;
974 for (int try_count = 1; /* we'll return */; try_count += 1) {
975 bool should_try_gc;
976 unsigned int gc_count_before;
977
978 {
979 MutexLockerEx x(Heap_lock);
980
981 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
982 false /* bot_updates */);
983 if (result != NULL) {
984 return result;
985 }
986
987 // If we reach here, attempt_allocation_locked() above failed to
988 // allocate a new region. So the mutator alloc region should be NULL.
989 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
990
991 if (GC_locker::is_active_and_needs_gc()) {
992 if (g1_policy()->can_expand_young_list()) {
993 // No need for an ergo verbose message here,
994 // can_expand_young_list() does this when it returns true.
995 result = _mutator_alloc_region.attempt_allocation_force(word_size,
996 false /* bot_updates */);
997 if (result != NULL) {
998 return result;
999 }
1000 }
1001 should_try_gc = false;
1002 } else {
1003 // The GCLocker may not be active but the GCLocker initiated
1004 // GC may not yet have been performed (GCLocker::needs_gc()
1005 // returns true). In this case we do not try this GC and
1006 // wait until the GCLocker initiated GC is performed, and
1007 // then retry the allocation.
1008 if (GC_locker::needs_gc()) {
1009 should_try_gc = false;
1010 } else {
1011 // Read the GC count while still holding the Heap_lock.
1012 gc_count_before = total_collections();
1013 should_try_gc = true;
1014 }
1015 }
1016 }
1017
1018 if (should_try_gc) {
1019 bool succeeded;
1020 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1021 if (result != NULL) {
1022 assert(succeeded, "only way to get back a non-NULL result");
1023 return result;
1024 }
1025
1026 if (succeeded) {
1027 // If we get here we successfully scheduled a collection which
1028 // failed to allocate. No point in trying to allocate
1029 // further. We'll just return NULL.
1030 MutexLockerEx x(Heap_lock);
1031 *gc_count_before_ret = total_collections();
1032 return NULL;
1033 }
1034 } else {
1035 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1036 MutexLockerEx x(Heap_lock);
1037 *gc_count_before_ret = total_collections();
1038 return NULL;
1039 }
1040 // The GCLocker is either active or the GCLocker initiated
1041 // GC has not yet been performed. Stall until it is and
1042 // then retry the allocation.
1043 GC_locker::stall_until_clear();
1044 (*gclocker_retry_count_ret) += 1;
1045 }
1046
1047 // We can reach here if we were unsuccessful in scheduling a
1048 // collection (because another thread beat us to it) or if we were
1049 // stalled due to the GC locker. In either can we should retry the
1050 // allocation attempt in case another thread successfully
1051 // performed a collection and reclaimed enough space. We do the
1052 // first attempt (without holding the Heap_lock) here and the
1053 // follow-on attempt will be at the start of the next loop
1054 // iteration (after taking the Heap_lock).
1055 result = _mutator_alloc_region.attempt_allocation(word_size,
1056 false /* bot_updates */);
1057 if (result != NULL) {
1058 return result;
1059 }
1060
1061 // Give a warning if we seem to be looping forever.
1062 if ((QueuedAllocationWarningCount > 0) &&
1063 (try_count % QueuedAllocationWarningCount == 0)) {
1064 warning("G1CollectedHeap::attempt_allocation_slow() "
1065 "retries %d times", try_count);
1066 }
1067 }
1068
1069 ShouldNotReachHere();
1070 return NULL;
1071 }
1072
1073 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1074 unsigned int * gc_count_before_ret,
1075 int* gclocker_retry_count_ret) {
1076 // The structure of this method has a lot of similarities to
1077 // attempt_allocation_slow(). The reason these two were not merged
1078 // into a single one is that such a method would require several "if
1079 // allocation is not humongous do this, otherwise do that"
1080 // conditional paths which would obscure its flow. In fact, an early
1081 // version of this code did use a unified method which was harder to
1082 // follow and, as a result, it had subtle bugs that were hard to
1083 // track down. So keeping these two methods separate allows each to
1084 // be more readable. It will be good to keep these two in sync as
1085 // much as possible.
1086
1087 assert_heap_not_locked_and_not_at_safepoint();
1088 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1089 "should only be called for humongous allocations");
1090
1091 // Humongous objects can exhaust the heap quickly, so we should check if we
1092 // need to start a marking cycle at each humongous object allocation. We do
1093 // the check before we do the actual allocation. The reason for doing it
1094 // before the allocation is that we avoid having to keep track of the newly
1095 // allocated memory while we do a GC.
1096 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1097 word_size)) {
1098 collect(GCCause::_g1_humongous_allocation);
1099 }
1100
1101 // We will loop until a) we manage to successfully perform the
1102 // allocation or b) we successfully schedule a collection which
1103 // fails to perform the allocation. b) is the only case when we'll
1104 // return NULL.
1105 HeapWord* result = NULL;
1106 for (int try_count = 1; /* we'll return */; try_count += 1) {
1107 bool should_try_gc;
1108 unsigned int gc_count_before;
1109
1110 {
1111 MutexLockerEx x(Heap_lock);
1112
1113 // Given that humongous objects are not allocated in young
1114 // regions, we'll first try to do the allocation without doing a
1115 // collection hoping that there's enough space in the heap.
1116 result = humongous_obj_allocate(word_size);
1117 if (result != NULL) {
1118 return result;
1119 }
1120
1121 if (GC_locker::is_active_and_needs_gc()) {
1122 should_try_gc = false;
1123 } else {
1124 // The GCLocker may not be active but the GCLocker initiated
1125 // GC may not yet have been performed (GCLocker::needs_gc()
1126 // returns true). In this case we do not try this GC and
1127 // wait until the GCLocker initiated GC is performed, and
1128 // then retry the allocation.
1129 if (GC_locker::needs_gc()) {
1130 should_try_gc = false;
1131 } else {
1132 // Read the GC count while still holding the Heap_lock.
1133 gc_count_before = total_collections();
1134 should_try_gc = true;
1135 }
1136 }
1137 }
1138
1139 if (should_try_gc) {
1140 // If we failed to allocate the humongous object, we should try to
1141 // do a collection pause (if we're allowed) in case it reclaims
1142 // enough space for the allocation to succeed after the pause.
1143
1144 bool succeeded;
1145 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1146 if (result != NULL) {
1147 assert(succeeded, "only way to get back a non-NULL result");
1148 return result;
1149 }
1150
1151 if (succeeded) {
1152 // If we get here we successfully scheduled a collection which
1153 // failed to allocate. No point in trying to allocate
1154 // further. We'll just return NULL.
1155 MutexLockerEx x(Heap_lock);
1156 *gc_count_before_ret = total_collections();
1157 return NULL;
1158 }
1159 } else {
1160 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1161 MutexLockerEx x(Heap_lock);
1162 *gc_count_before_ret = total_collections();
1163 return NULL;
1164 }
1165 // The GCLocker is either active or the GCLocker initiated
1166 // GC has not yet been performed. Stall until it is and
1167 // then retry the allocation.
1168 GC_locker::stall_until_clear();
1169 (*gclocker_retry_count_ret) += 1;
1170 }
1171
1172 // We can reach here if we were unsuccessful in scheduling a
1173 // collection (because another thread beat us to it) or if we were
1174 // stalled due to the GC locker. In either can we should retry the
1175 // allocation attempt in case another thread successfully
1176 // performed a collection and reclaimed enough space. Give a
1177 // warning if we seem to be looping forever.
1178
1179 if ((QueuedAllocationWarningCount > 0) &&
1180 (try_count % QueuedAllocationWarningCount == 0)) {
1181 warning("G1CollectedHeap::attempt_allocation_humongous() "
1182 "retries %d times", try_count);
1183 }
1184 }
1185
1186 ShouldNotReachHere();
1187 return NULL;
1188 }
1189
1190 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1191 bool expect_null_mutator_alloc_region) {
1192 assert_at_safepoint(true /* should_be_vm_thread */);
1193 assert(_mutator_alloc_region.get() == NULL ||
1194 !expect_null_mutator_alloc_region,
1195 "the current alloc region was unexpectedly found to be non-NULL");
1196
1197 if (!isHumongous(word_size)) {
1198 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1199 false /* bot_updates */);
1200 } else {
1201 HeapWord* result = humongous_obj_allocate(word_size);
1202 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1203 g1_policy()->set_initiate_conc_mark_if_possible();
1204 }
1205 return result;
1206 }
1207
1208 ShouldNotReachHere();
1209 }
1210
1211 class PostMCRemSetClearClosure: public HeapRegionClosure {
1212 G1CollectedHeap* _g1h;
1213 ModRefBarrierSet* _mr_bs;
1214 public:
1215 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1216 _g1h(g1h), _mr_bs(mr_bs) { }
1217 bool doHeapRegion(HeapRegion* r) {
1218 if (r->continuesHumongous()) {
1219 return false;
1220 }
1221 _g1h->reset_gc_time_stamps(r);
1222 HeapRegionRemSet* hrrs = r->rem_set();
1223 if (hrrs != NULL) hrrs->clear();
1224 // You might think here that we could clear just the cards
1225 // corresponding to the used region. But no: if we leave a dirty card
1226 // in a region we might allocate into, then it would prevent that card
1227 // from being enqueued, and cause it to be missed.
1228 // Re: the performance cost: we shouldn't be doing full GC anyway!
1229 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1230 return false;
1231 }
1232 };
1233
1234 void G1CollectedHeap::clear_rsets_post_compaction() {
1235 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1236 heap_region_iterate(&rs_clear);
1237 }
1238
1239 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1240 G1CollectedHeap* _g1h;
1241 UpdateRSOopClosure _cl;
1242 int _worker_i;
1243 public:
1244 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1245 _cl(g1->g1_rem_set(), worker_i),
1246 _worker_i(worker_i),
1247 _g1h(g1)
1248 { }
1249
1250 bool doHeapRegion(HeapRegion* r) {
1251 if (!r->continuesHumongous()) {
1252 _cl.set_from(r);
1253 r->oop_iterate(&_cl);
1254 }
1255 return false;
1256 }
1257 };
1258
1259 class ParRebuildRSTask: public AbstractGangTask {
1260 G1CollectedHeap* _g1;
1261 public:
1262 ParRebuildRSTask(G1CollectedHeap* g1)
1263 : AbstractGangTask("ParRebuildRSTask"),
1264 _g1(g1)
1265 { }
1266
1267 void work(uint worker_id) {
1268 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1269 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1270 _g1->workers()->active_workers(),
1271 HeapRegion::RebuildRSClaimValue);
1272 }
1273 };
1274
1275 class PostCompactionPrinterClosure: public HeapRegionClosure {
1276 private:
1277 G1HRPrinter* _hr_printer;
1278 public:
1279 bool doHeapRegion(HeapRegion* hr) {
1280 assert(!hr->is_young(), "not expecting to find young regions");
1281 // We only generate output for non-empty regions.
1282 if (!hr->is_empty()) {
1283 if (!hr->isHumongous()) {
1284 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1285 } else if (hr->startsHumongous()) {
1286 if (hr->region_num() == 1) {
1287 // single humongous region
1288 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1289 } else {
1290 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1291 }
1292 } else {
1293 assert(hr->continuesHumongous(), "only way to get here");
1294 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1295 }
1296 }
1297 return false;
1298 }
1299
1300 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1301 : _hr_printer(hr_printer) { }
1302 };
1303
1304 void G1CollectedHeap::print_hrs_post_compaction() {
1305 PostCompactionPrinterClosure cl(hr_printer());
1306 heap_region_iterate(&cl);
1307 }
1308
1309 double G1CollectedHeap::verify(bool guard, const char* msg) {
1310 double verify_time_ms = 0.0;
1311
1312 if (guard && total_collections() >= VerifyGCStartAt) {
1313 double verify_start = os::elapsedTime();
1314 HandleMark hm; // Discard invalid handles created during verification
1315 prepare_for_verify();
1316 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
1317 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
1318 }
1319
1320 return verify_time_ms;
1321 }
1322
1323 void G1CollectedHeap::verify_before_gc() {
1324 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
1325 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
1326 }
1327
1328 void G1CollectedHeap::verify_after_gc() {
1329 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
1330 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
1331 }
1332
1333 bool G1CollectedHeap::do_collection(bool explicit_gc,
1334 bool clear_all_soft_refs,
1335 size_t word_size) {
1336 assert_at_safepoint(true /* should_be_vm_thread */);
1337
1338 if (GC_locker::check_active_before_gc()) {
1339 return false;
1340 }
1341
1342 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1343 gc_timer->register_gc_start(os::elapsed_counter());
1344
1345 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1346 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1347
1348 SvcGCMarker sgcm(SvcGCMarker::FULL);
1349 ResourceMark rm;
1350
1351 print_heap_before_gc();
1352 trace_heap_before_gc(gc_tracer);
1353
1354 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1355
1356 HRSPhaseSetter x(HRSPhaseFullGC);
1357 verify_region_sets_optional();
1358
1359 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1360 collector_policy()->should_clear_all_soft_refs();
1361
1362 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1363
1364 {
1365 IsGCActiveMark x;
1366
1367 // Timing
1368 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1369 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1370 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1371
1372 {
1373 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1374 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1375 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1376
1377 double start = os::elapsedTime();
1378 g1_policy()->record_full_collection_start();
1379
1380 // Note: When we have a more flexible GC logging framework that
1381 // allows us to add optional attributes to a GC log record we
1382 // could consider timing and reporting how long we wait in the
1383 // following two methods.
1384 wait_while_free_regions_coming();
1385 // If we start the compaction before the CM threads finish
1386 // scanning the root regions we might trip them over as we'll
1387 // be moving objects / updating references. So let's wait until
1388 // they are done. By telling them to abort, they should complete
1389 // early.
1390 _cm->root_regions()->abort();
1391 _cm->root_regions()->wait_until_scan_finished();
1392 append_secondary_free_list_if_not_empty_with_lock();
1393
1394 gc_prologue(true);
1395 increment_total_collections(true /* full gc */);
1396 increment_old_marking_cycles_started();
1397
1398 assert(used() == recalculate_used(), "Should be equal");
1399
1400 verify_before_gc();
1401
1402 pre_full_gc_dump(gc_timer);
1403
1404 COMPILER2_PRESENT(DerivedPointerTable::clear());
1405
1406 // Disable discovery and empty the discovered lists
1407 // for the CM ref processor.
1408 ref_processor_cm()->disable_discovery();
1409 ref_processor_cm()->abandon_partial_discovery();
1410 ref_processor_cm()->verify_no_references_recorded();
1411
1412 // Abandon current iterations of concurrent marking and concurrent
1413 // refinement, if any are in progress. We have to do this before
1414 // wait_until_scan_finished() below.
1415 concurrent_mark()->abort();
1416
1417 // Make sure we'll choose a new allocation region afterwards.
1418 release_mutator_alloc_region();
1419 abandon_gc_alloc_regions();
1420 g1_rem_set()->cleanupHRRS();
1421
1422 // We should call this after we retire any currently active alloc
1423 // regions so that all the ALLOC / RETIRE events are generated
1424 // before the start GC event.
1425 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1426
1427 // We may have added regions to the current incremental collection
1428 // set between the last GC or pause and now. We need to clear the
1429 // incremental collection set and then start rebuilding it afresh
1430 // after this full GC.
1431 abandon_collection_set(g1_policy()->inc_cset_head());
1432 g1_policy()->clear_incremental_cset();
1433 g1_policy()->stop_incremental_cset_building();
1434
1435 tear_down_region_sets(false /* free_list_only */);
1436 g1_policy()->set_gcs_are_young(true);
1437
1438 // See the comments in g1CollectedHeap.hpp and
1439 // G1CollectedHeap::ref_processing_init() about
1440 // how reference processing currently works in G1.
1441
1442 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1443 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1444
1445 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1446 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1447
1448 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1449 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1450
1451 // Do collection work
1452 {
1453 HandleMark hm; // Discard invalid handles created during gc
1454 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1455 }
1456
1457 assert(free_regions() == 0, "we should not have added any free regions");
1458 rebuild_region_sets(false /* free_list_only */);
1459
1460 // Enqueue any discovered reference objects that have
1461 // not been removed from the discovered lists.
1462 ref_processor_stw()->enqueue_discovered_references();
1463
1464 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1465
1466 MemoryService::track_memory_usage();
1467
1468 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1469 ref_processor_stw()->verify_no_references_recorded();
1470
1471 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1472 ClassLoaderDataGraph::purge();
1473 MetaspaceAux::verify_metrics();
1474
1475 // Note: since we've just done a full GC, concurrent
1476 // marking is no longer active. Therefore we need not
1477 // re-enable reference discovery for the CM ref processor.
1478 // That will be done at the start of the next marking cycle.
1479 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1480 ref_processor_cm()->verify_no_references_recorded();
1481
1482 reset_gc_time_stamp();
1483 // Since everything potentially moved, we will clear all remembered
1484 // sets, and clear all cards. Later we will rebuild remembered
1485 // sets. We will also reset the GC time stamps of the regions.
1486 clear_rsets_post_compaction();
1487 check_gc_time_stamps();
1488
1489 // Resize the heap if necessary.
1490 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1491
1492 if (_hr_printer.is_active()) {
1493 // We should do this after we potentially resize the heap so
1494 // that all the COMMIT / UNCOMMIT events are generated before
1495 // the end GC event.
1496
1497 print_hrs_post_compaction();
1498 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1499 }
1500
1501 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1502 if (hot_card_cache->use_cache()) {
1503 hot_card_cache->reset_card_counts();
1504 hot_card_cache->reset_hot_cache();
1505 }
1506
1507 // Rebuild remembered sets of all regions.
1508 if (G1CollectedHeap::use_parallel_gc_threads()) {
1509 uint n_workers =
1510 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1511 workers()->active_workers(),
1512 Threads::number_of_non_daemon_threads());
1513 assert(UseDynamicNumberOfGCThreads ||
1514 n_workers == workers()->total_workers(),
1515 "If not dynamic should be using all the workers");
1516 workers()->set_active_workers(n_workers);
1517 // Set parallel threads in the heap (_n_par_threads) only
1518 // before a parallel phase and always reset it to 0 after
1519 // the phase so that the number of parallel threads does
1520 // no get carried forward to a serial phase where there
1521 // may be code that is "possibly_parallel".
1522 set_par_threads(n_workers);
1523
1524 ParRebuildRSTask rebuild_rs_task(this);
1525 assert(check_heap_region_claim_values(
1526 HeapRegion::InitialClaimValue), "sanity check");
1527 assert(UseDynamicNumberOfGCThreads ||
1528 workers()->active_workers() == workers()->total_workers(),
1529 "Unless dynamic should use total workers");
1530 // Use the most recent number of active workers
1531 assert(workers()->active_workers() > 0,
1532 "Active workers not properly set");
1533 set_par_threads(workers()->active_workers());
1534 workers()->run_task(&rebuild_rs_task);
1535 set_par_threads(0);
1536 assert(check_heap_region_claim_values(
1537 HeapRegion::RebuildRSClaimValue), "sanity check");
1538 reset_heap_region_claim_values();
1539 } else {
1540 RebuildRSOutOfRegionClosure rebuild_rs(this);
1541 heap_region_iterate(&rebuild_rs);
1542 }
1543
1544 if (true) { // FIXME
1545 MetaspaceGC::compute_new_size();
1546 }
1547
1548 #ifdef TRACESPINNING
1549 ParallelTaskTerminator::print_termination_counts();
1550 #endif
1551
1552 // Discard all rset updates
1553 JavaThread::dirty_card_queue_set().abandon_logs();
1554 assert(!G1DeferredRSUpdate
1555 || (G1DeferredRSUpdate &&
1556 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1557
1558 _young_list->reset_sampled_info();
1559 // At this point there should be no regions in the
1560 // entire heap tagged as young.
1561 assert(check_young_list_empty(true /* check_heap */),
1562 "young list should be empty at this point");
1563
1564 // Update the number of full collections that have been completed.
1565 increment_old_marking_cycles_completed(false /* concurrent */);
1566
1567 _hrs.verify_optional();
1568 verify_region_sets_optional();
1569
1570 verify_after_gc();
1571
1572 // Start a new incremental collection set for the next pause
1573 assert(g1_policy()->collection_set() == NULL, "must be");
1574 g1_policy()->start_incremental_cset_building();
1575
1576 // Clear the _cset_fast_test bitmap in anticipation of adding
1577 // regions to the incremental collection set for the next
1578 // evacuation pause.
1579 clear_cset_fast_test();
1580
1581 init_mutator_alloc_region();
1582
1583 double end = os::elapsedTime();
1584 g1_policy()->record_full_collection_end();
1585
1586 if (G1Log::fine()) {
1587 g1_policy()->print_heap_transition();
1588 }
1589
1590 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1591 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1592 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1593 // before any GC notifications are raised.
1594 g1mm()->update_sizes();
1595
1596 gc_epilogue(true);
1597 }
1598
1599 if (G1Log::finer()) {
1600 g1_policy()->print_detailed_heap_transition(true /* full */);
1601 }
1602
1603 print_heap_after_gc();
1604 trace_heap_after_gc(gc_tracer);
1605
1606 post_full_gc_dump(gc_timer);
1607
1608 gc_timer->register_gc_end(os::elapsed_counter());
1609 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1610 }
1611
1612 return true;
1613 }
1614
1615 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1616 // do_collection() will return whether it succeeded in performing
1617 // the GC. Currently, there is no facility on the
1618 // do_full_collection() API to notify the caller than the collection
1619 // did not succeed (e.g., because it was locked out by the GC
1620 // locker). So, right now, we'll ignore the return value.
1621 bool dummy = do_collection(true, /* explicit_gc */
1622 clear_all_soft_refs,
1623 0 /* word_size */);
1624 }
1625
1626 // This code is mostly copied from TenuredGeneration.
1627 void
1628 G1CollectedHeap::
1629 resize_if_necessary_after_full_collection(size_t word_size) {
1630 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1631
1632 // Include the current allocation, if any, and bytes that will be
1633 // pre-allocated to support collections, as "used".
1634 const size_t used_after_gc = used();
1635 const size_t capacity_after_gc = capacity();
1636 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1637
1638 // This is enforced in arguments.cpp.
1639 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1640 "otherwise the code below doesn't make sense");
1641
1642 // We don't have floating point command-line arguments
1643 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1644 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1645 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1646 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1647
1648 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1649 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1650
1651 // We have to be careful here as these two calculations can overflow
1652 // 32-bit size_t's.
1653 double used_after_gc_d = (double) used_after_gc;
1654 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1655 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1656
1657 // Let's make sure that they are both under the max heap size, which
1658 // by default will make them fit into a size_t.
1659 double desired_capacity_upper_bound = (double) max_heap_size;
1660 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1661 desired_capacity_upper_bound);
1662 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1663 desired_capacity_upper_bound);
1664
1665 // We can now safely turn them into size_t's.
1666 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1667 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1668
1669 // This assert only makes sense here, before we adjust them
1670 // with respect to the min and max heap size.
1671 assert(minimum_desired_capacity <= maximum_desired_capacity,
1672 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1673 "maximum_desired_capacity = "SIZE_FORMAT,
1674 minimum_desired_capacity, maximum_desired_capacity));
1675
1676 // Should not be greater than the heap max size. No need to adjust
1677 // it with respect to the heap min size as it's a lower bound (i.e.,
1678 // we'll try to make the capacity larger than it, not smaller).
1679 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1680 // Should not be less than the heap min size. No need to adjust it
1681 // with respect to the heap max size as it's an upper bound (i.e.,
1682 // we'll try to make the capacity smaller than it, not greater).
1683 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1684
1685 if (capacity_after_gc < minimum_desired_capacity) {
1686 // Don't expand unless it's significant
1687 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1688 ergo_verbose4(ErgoHeapSizing,
1689 "attempt heap expansion",
1690 ergo_format_reason("capacity lower than "
1691 "min desired capacity after Full GC")
1692 ergo_format_byte("capacity")
1693 ergo_format_byte("occupancy")
1694 ergo_format_byte_perc("min desired capacity"),
1695 capacity_after_gc, used_after_gc,
1696 minimum_desired_capacity, (double) MinHeapFreeRatio);
1697 expand(expand_bytes);
1698
1699 // No expansion, now see if we want to shrink
1700 } else if (capacity_after_gc > maximum_desired_capacity) {
1701 // Capacity too large, compute shrinking size
1702 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1703 ergo_verbose4(ErgoHeapSizing,
1704 "attempt heap shrinking",
1705 ergo_format_reason("capacity higher than "
1706 "max desired capacity after Full GC")
1707 ergo_format_byte("capacity")
1708 ergo_format_byte("occupancy")
1709 ergo_format_byte_perc("max desired capacity"),
1710 capacity_after_gc, used_after_gc,
1711 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1712 shrink(shrink_bytes);
1713 }
1714 }
1715
1716
1717 HeapWord*
1718 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1719 bool* succeeded) {
1720 assert_at_safepoint(true /* should_be_vm_thread */);
1721
1722 *succeeded = true;
1723 // Let's attempt the allocation first.
1724 HeapWord* result =
1725 attempt_allocation_at_safepoint(word_size,
1726 false /* expect_null_mutator_alloc_region */);
1727 if (result != NULL) {
1728 assert(*succeeded, "sanity");
1729 return result;
1730 }
1731
1732 // In a G1 heap, we're supposed to keep allocation from failing by
1733 // incremental pauses. Therefore, at least for now, we'll favor
1734 // expansion over collection. (This might change in the future if we can
1735 // do something smarter than full collection to satisfy a failed alloc.)
1736 result = expand_and_allocate(word_size);
1737 if (result != NULL) {
1738 assert(*succeeded, "sanity");
1739 return result;
1740 }
1741
1742 // Expansion didn't work, we'll try to do a Full GC.
1743 bool gc_succeeded = do_collection(false, /* explicit_gc */
1744 false, /* clear_all_soft_refs */
1745 word_size);
1746 if (!gc_succeeded) {
1747 *succeeded = false;
1748 return NULL;
1749 }
1750
1751 // Retry the allocation
1752 result = attempt_allocation_at_safepoint(word_size,
1753 true /* expect_null_mutator_alloc_region */);
1754 if (result != NULL) {
1755 assert(*succeeded, "sanity");
1756 return result;
1757 }
1758
1759 // Then, try a Full GC that will collect all soft references.
1760 gc_succeeded = do_collection(false, /* explicit_gc */
1761 true, /* clear_all_soft_refs */
1762 word_size);
1763 if (!gc_succeeded) {
1764 *succeeded = false;
1765 return NULL;
1766 }
1767
1768 // Retry the allocation once more
1769 result = attempt_allocation_at_safepoint(word_size,
1770 true /* expect_null_mutator_alloc_region */);
1771 if (result != NULL) {
1772 assert(*succeeded, "sanity");
1773 return result;
1774 }
1775
1776 assert(!collector_policy()->should_clear_all_soft_refs(),
1777 "Flag should have been handled and cleared prior to this point");
1778
1779 // What else? We might try synchronous finalization later. If the total
1780 // space available is large enough for the allocation, then a more
1781 // complete compaction phase than we've tried so far might be
1782 // appropriate.
1783 assert(*succeeded, "sanity");
1784 return NULL;
1785 }
1786
1787 // Attempting to expand the heap sufficiently
1788 // to support an allocation of the given "word_size". If
1789 // successful, perform the allocation and return the address of the
1790 // allocated block, or else "NULL".
1791
1792 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1793 assert_at_safepoint(true /* should_be_vm_thread */);
1794
1795 verify_region_sets_optional();
1796
1797 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1798 ergo_verbose1(ErgoHeapSizing,
1799 "attempt heap expansion",
1800 ergo_format_reason("allocation request failed")
1801 ergo_format_byte("allocation request"),
1802 word_size * HeapWordSize);
1803 if (expand(expand_bytes)) {
1804 _hrs.verify_optional();
1805 verify_region_sets_optional();
1806 return attempt_allocation_at_safepoint(word_size,
1807 false /* expect_null_mutator_alloc_region */);
1808 }
1809 return NULL;
1810 }
1811
1812 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1813 HeapWord* new_end) {
1814 assert(old_end != new_end, "don't call this otherwise");
1815 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1816
1817 // Update the committed mem region.
1818 _g1_committed.set_end(new_end);
1819 // Tell the card table about the update.
1820 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1821 // Tell the BOT about the update.
1822 _bot_shared->resize(_g1_committed.word_size());
1823 // Tell the hot card cache about the update
1824 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1825 }
1826
1827 bool G1CollectedHeap::expand(size_t expand_bytes) {
1828 size_t old_mem_size = _g1_storage.committed_size();
1829 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1830 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1831 HeapRegion::GrainBytes);
1832 ergo_verbose2(ErgoHeapSizing,
1833 "expand the heap",
1834 ergo_format_byte("requested expansion amount")
1835 ergo_format_byte("attempted expansion amount"),
1836 expand_bytes, aligned_expand_bytes);
1837
1838 // First commit the memory.
1839 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1840 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1841 if (successful) {
1842 // Then propagate this update to the necessary data structures.
1843 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1844 update_committed_space(old_end, new_end);
1845
1846 FreeRegionList expansion_list("Local Expansion List");
1847 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1848 assert(mr.start() == old_end, "post-condition");
1849 // mr might be a smaller region than what was requested if
1850 // expand_by() was unable to allocate the HeapRegion instances
1851 assert(mr.end() <= new_end, "post-condition");
1852
1853 size_t actual_expand_bytes = mr.byte_size();
1854 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1855 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1856 "post-condition");
1857 if (actual_expand_bytes < aligned_expand_bytes) {
1858 // We could not expand _hrs to the desired size. In this case we
1859 // need to shrink the committed space accordingly.
1860 assert(mr.end() < new_end, "invariant");
1861
1862 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1863 // First uncommit the memory.
1864 _g1_storage.shrink_by(diff_bytes);
1865 // Then propagate this update to the necessary data structures.
1866 update_committed_space(new_end, mr.end());
1867 }
1868 _free_list.add_as_tail(&expansion_list);
1869
1870 if (_hr_printer.is_active()) {
1871 HeapWord* curr = mr.start();
1872 while (curr < mr.end()) {
1873 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1874 _hr_printer.commit(curr, curr_end);
1875 curr = curr_end;
1876 }
1877 assert(curr == mr.end(), "post-condition");
1878 }
1879 g1_policy()->record_new_heap_size(n_regions());
1880 } else {
1881 ergo_verbose0(ErgoHeapSizing,
1882 "did not expand the heap",
1883 ergo_format_reason("heap expansion operation failed"));
1884 // The expansion of the virtual storage space was unsuccessful.
1885 // Let's see if it was because we ran out of swap.
1886 if (G1ExitOnExpansionFailure &&
1887 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1888 // We had head room...
1889 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1890 }
1891 }
1892 return successful;
1893 }
1894
1895 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1896 size_t old_mem_size = _g1_storage.committed_size();
1897 size_t aligned_shrink_bytes =
1898 ReservedSpace::page_align_size_down(shrink_bytes);
1899 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1900 HeapRegion::GrainBytes);
1901 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1902
1903 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1904 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1905 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1906
1907 ergo_verbose3(ErgoHeapSizing,
1908 "shrink the heap",
1909 ergo_format_byte("requested shrinking amount")
1910 ergo_format_byte("aligned shrinking amount")
1911 ergo_format_byte("attempted shrinking amount"),
1912 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1913 if (num_regions_removed > 0) {
1914 _g1_storage.shrink_by(shrunk_bytes);
1915 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1916
1917 if (_hr_printer.is_active()) {
1918 HeapWord* curr = old_end;
1919 while (curr > new_end) {
1920 HeapWord* curr_end = curr;
1921 curr -= HeapRegion::GrainWords;
1922 _hr_printer.uncommit(curr, curr_end);
1923 }
1924 }
1925
1926 _expansion_regions += num_regions_removed;
1927 update_committed_space(old_end, new_end);
1928 HeapRegionRemSet::shrink_heap(n_regions());
1929 g1_policy()->record_new_heap_size(n_regions());
1930 } else {
1931 ergo_verbose0(ErgoHeapSizing,
1932 "did not shrink the heap",
1933 ergo_format_reason("heap shrinking operation failed"));
1934 }
1935 }
1936
1937 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1938 verify_region_sets_optional();
1939
1940 // We should only reach here at the end of a Full GC which means we
1941 // should not not be holding to any GC alloc regions. The method
1942 // below will make sure of that and do any remaining clean up.
1943 abandon_gc_alloc_regions();
1944
1945 // Instead of tearing down / rebuilding the free lists here, we
1946 // could instead use the remove_all_pending() method on free_list to
1947 // remove only the ones that we need to remove.
1948 tear_down_region_sets(true /* free_list_only */);
1949 shrink_helper(shrink_bytes);
1950 rebuild_region_sets(true /* free_list_only */);
1951
1952 _hrs.verify_optional();
1953 verify_region_sets_optional();
1954 }
1955
1956 // Public methods.
1957
1958 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1959 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1960 #endif // _MSC_VER
1961
1962
1963 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1964 SharedHeap(policy_),
1965 _g1_policy(policy_),
1966 _dirty_card_queue_set(false),
1967 _into_cset_dirty_card_queue_set(false),
1968 _is_alive_closure_cm(this),
1969 _is_alive_closure_stw(this),
1970 _ref_processor_cm(NULL),
1971 _ref_processor_stw(NULL),
1972 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1973 _bot_shared(NULL),
1974 _evac_failure_scan_stack(NULL),
1975 _mark_in_progress(false),
1976 _cg1r(NULL), _summary_bytes_used(0),
1977 _g1mm(NULL),
1978 _refine_cte_cl(NULL),
1979 _transfer_cte_cl(NULL),
1980 _full_collection(false),
1981 _free_list("Master Free List"),
1982 _secondary_free_list("Secondary Free List"),
1983 _old_set("Old Set"),
1984 _humongous_set("Master Humongous Set"),
1985 _free_regions_coming(false),
1986 _young_list(new YoungList(this)),
1987 _gc_time_stamp(0),
1988 _retained_old_gc_alloc_region(NULL),
1989 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1990 _old_plab_stats(OldPLABSize, PLABWeight),
1991 _expand_heap_after_alloc_failure(true),
1992 _surviving_young_words(NULL),
1993 _old_marking_cycles_started(0),
1994 _old_marking_cycles_completed(0),
1995 _concurrent_cycle_started(false),
1996 _in_cset_fast_test(NULL),
1997 _in_cset_fast_test_base(NULL),
1998 _dirty_cards_region_list(NULL),
1999 _worker_cset_start_region(NULL),
2000 _worker_cset_start_region_time_stamp(NULL),
2001 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2002 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2003 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2004 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2005
2006 _g1h = this;
2007 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
2008 vm_exit_during_initialization("Failed necessary allocation.");
2009 }
2010
2011 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
2012
2013 int n_queues = MAX2((int)ParallelGCThreads, 1);
2014 _task_queues = new RefToScanQueueSet(n_queues);
2015
2016 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2017 assert(n_rem_sets > 0, "Invariant.");
2018
2019 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2020 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
2021 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2022
2023 for (int i = 0; i < n_queues; i++) {
2024 RefToScanQueue* q = new RefToScanQueue();
2025 q->initialize();
2026 _task_queues->register_queue(i, q);
2027 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2028 }
2029 clear_cset_start_regions();
2030
2031 // Initialize the G1EvacuationFailureALot counters and flags.
2032 NOT_PRODUCT(reset_evacuation_should_fail();)
2033
2034 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2035 }
2036
2037 jint G1CollectedHeap::initialize() {
2038 CollectedHeap::pre_initialize();
2039 os::enable_vtime();
2040
2041 G1Log::init();
2042
2043 // Necessary to satisfy locking discipline assertions.
2044
2045 MutexLocker x(Heap_lock);
2046
2047 // We have to initialize the printer before committing the heap, as
2048 // it will be used then.
2049 _hr_printer.set_active(G1PrintHeapRegions);
2050
2051 // While there are no constraints in the GC code that HeapWordSize
2052 // be any particular value, there are multiple other areas in the
2053 // system which believe this to be true (e.g. oop->object_size in some
2054 // cases incorrectly returns the size in wordSize units rather than
2055 // HeapWordSize).
2056 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2057
2058 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2059 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2060
2061 // Ensure that the sizes are properly aligned.
2062 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2063 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2064
2065 _cg1r = new ConcurrentG1Refine(this);
2066
2067 // Reserve the maximum.
2068
2069 // When compressed oops are enabled, the preferred heap base
2070 // is calculated by subtracting the requested size from the
2071 // 32Gb boundary and using the result as the base address for
2072 // heap reservation. If the requested size is not aligned to
2073 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2074 // into the ReservedHeapSpace constructor) then the actual
2075 // base of the reserved heap may end up differing from the
2076 // address that was requested (i.e. the preferred heap base).
2077 // If this happens then we could end up using a non-optimal
2078 // compressed oops mode.
2079
2080 // Since max_byte_size is aligned to the size of a heap region (checked
2081 // above).
2082 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2083
2084 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2085 HeapRegion::GrainBytes);
2086
2087 // It is important to do this in a way such that concurrent readers can't
2088 // temporarily think something is in the heap. (I've actually seen this
2089 // happen in asserts: DLD.)
2090 _reserved.set_word_size(0);
2091 _reserved.set_start((HeapWord*)heap_rs.base());
2092 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2093
2094 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2095
2096 // Create the gen rem set (and barrier set) for the entire reserved region.
2097 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2098 set_barrier_set(rem_set()->bs());
2099 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2100 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2101 } else {
2102 vm_exit_during_initialization("G1 requires a mod ref bs.");
2103 return JNI_ENOMEM;
2104 }
2105
2106 // Also create a G1 rem set.
2107 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2108 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2109 } else {
2110 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2111 return JNI_ENOMEM;
2112 }
2113
2114 // Carve out the G1 part of the heap.
2115
2116 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2117 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2118 g1_rs.size()/HeapWordSize);
2119
2120 _g1_storage.initialize(g1_rs, 0);
2121 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2122 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2123 (HeapWord*) _g1_reserved.end(),
2124 _expansion_regions);
2125
2126 // Do later initialization work for concurrent refinement.
2127 _cg1r->init();
2128
2129 // 6843694 - ensure that the maximum region index can fit
2130 // in the remembered set structures.
2131 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2132 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2133
2134 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2135 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2136 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2137 "too many cards per region");
2138
2139 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2140
2141 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2142 heap_word_size(init_byte_size));
2143
2144 _g1h = this;
2145
2146 _in_cset_fast_test_length = max_regions();
2147 _in_cset_fast_test_base =
2148 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2149
2150 // We're biasing _in_cset_fast_test to avoid subtracting the
2151 // beginning of the heap every time we want to index; basically
2152 // it's the same with what we do with the card table.
2153 _in_cset_fast_test = _in_cset_fast_test_base -
2154 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2155
2156 // Clear the _cset_fast_test bitmap in anticipation of adding
2157 // regions to the incremental collection set for the first
2158 // evacuation pause.
2159 clear_cset_fast_test();
2160
2161 // Create the ConcurrentMark data structure and thread.
2162 // (Must do this late, so that "max_regions" is defined.)
2163 _cm = new ConcurrentMark(this, heap_rs);
2164 if (_cm == NULL || !_cm->completed_initialization()) {
2165 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2166 return JNI_ENOMEM;
2167 }
2168 _cmThread = _cm->cmThread();
2169
2170 // Initialize the from_card cache structure of HeapRegionRemSet.
2171 HeapRegionRemSet::init_heap(max_regions());
2172
2173 // Now expand into the initial heap size.
2174 if (!expand(init_byte_size)) {
2175 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2176 return JNI_ENOMEM;
2177 }
2178
2179 // Perform any initialization actions delegated to the policy.
2180 g1_policy()->init();
2181
2182 _refine_cte_cl =
2183 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2184 g1_rem_set());
2185 _transfer_cte_cl =
2186 new TransferDirtyCardsToRefinementClosure(concurrent_g1_refine()->cards_ready_for_refinement());
2187
2188 concurrent_g1_refine()->set_card_refinement_closure(_refine_cte_cl);
2189 concurrent_g1_refine()->set_flush_transfer_closure(_transfer_cte_cl->flush_cl());
2190
2191 JavaThread::dirty_card_queue_set().set_closure(_transfer_cte_cl);
2192
2193 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2194 SATB_Q_FL_lock,
2195 G1SATBProcessCompletedThreshold,
2196 Shared_SATB_Q_lock);
2197
2198 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2199 DirtyCardQ_FL_lock,
2200 concurrent_g1_refine()->yellow_zone(),
2201 concurrent_g1_refine()->red_zone(),
2202 Shared_DirtyCardQ_lock);
2203
2204 if (G1DeferredRSUpdate) {
2205 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2206 DirtyCardQ_FL_lock,
2207 -1, // never trigger processing
2208 -1, // no limit on length
2209 Shared_DirtyCardQ_lock,
2210 &JavaThread::dirty_card_queue_set());
2211 }
2212
2213 // Initialize the card queue set used to hold cards containing
2214 // references into the collection set.
2215 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2216 DirtyCardQ_FL_lock,
2217 -1, // never trigger processing
2218 -1, // no limit on length
2219 Shared_DirtyCardQ_lock,
2220 &JavaThread::dirty_card_queue_set());
2221
2222 // In case we're keeping closure specialization stats, initialize those
2223 // counts and that mechanism.
2224 SpecializationStats::clear();
2225
2226 // Here we allocate the dummy full region that is required by the
2227 // G1AllocRegion class. If we don't pass an address in the reserved
2228 // space here, lots of asserts fire.
2229
2230 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2231 _g1_reserved.start());
2232 // We'll re-use the same region whether the alloc region will
2233 // require BOT updates or not and, if it doesn't, then a non-young
2234 // region will complain that it cannot support allocations without
2235 // BOT updates. So we'll tag the dummy region as young to avoid that.
2236 dummy_region->set_young();
2237 // Make sure it's full.
2238 dummy_region->set_top(dummy_region->end());
2239 G1AllocRegion::setup(this, dummy_region);
2240
2241 init_mutator_alloc_region();
2242
2243 // Do create of the monitoring and management support so that
2244 // values in the heap have been properly initialized.
2245 _g1mm = new G1MonitoringSupport(this);
2246
2247 return JNI_OK;
2248 }
2249
2250 void G1CollectedHeap::ref_processing_init() {
2251 // Reference processing in G1 currently works as follows:
2252 //
2253 // * There are two reference processor instances. One is
2254 // used to record and process discovered references
2255 // during concurrent marking; the other is used to
2256 // record and process references during STW pauses
2257 // (both full and incremental).
2258 // * Both ref processors need to 'span' the entire heap as
2259 // the regions in the collection set may be dotted around.
2260 //
2261 // * For the concurrent marking ref processor:
2262 // * Reference discovery is enabled at initial marking.
2263 // * Reference discovery is disabled and the discovered
2264 // references processed etc during remarking.
2265 // * Reference discovery is MT (see below).
2266 // * Reference discovery requires a barrier (see below).
2267 // * Reference processing may or may not be MT
2268 // (depending on the value of ParallelRefProcEnabled
2269 // and ParallelGCThreads).
2270 // * A full GC disables reference discovery by the CM
2271 // ref processor and abandons any entries on it's
2272 // discovered lists.
2273 //
2274 // * For the STW processor:
2275 // * Non MT discovery is enabled at the start of a full GC.
2276 // * Processing and enqueueing during a full GC is non-MT.
2277 // * During a full GC, references are processed after marking.
2278 //
2279 // * Discovery (may or may not be MT) is enabled at the start
2280 // of an incremental evacuation pause.
2281 // * References are processed near the end of a STW evacuation pause.
2282 // * For both types of GC:
2283 // * Discovery is atomic - i.e. not concurrent.
2284 // * Reference discovery will not need a barrier.
2285
2286 SharedHeap::ref_processing_init();
2287 MemRegion mr = reserved_region();
2288
2289 // Concurrent Mark ref processor
2290 _ref_processor_cm =
2291 new ReferenceProcessor(mr, // span
2292 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2293 // mt processing
2294 (int) ParallelGCThreads,
2295 // degree of mt processing
2296 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2297 // mt discovery
2298 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2299 // degree of mt discovery
2300 false,
2301 // Reference discovery is not atomic
2302 &_is_alive_closure_cm,
2303 // is alive closure
2304 // (for efficiency/performance)
2305 true);
2306 // Setting next fields of discovered
2307 // lists requires a barrier.
2308
2309 // STW ref processor
2310 _ref_processor_stw =
2311 new ReferenceProcessor(mr, // span
2312 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2313 // mt processing
2314 MAX2((int)ParallelGCThreads, 1),
2315 // degree of mt processing
2316 (ParallelGCThreads > 1),
2317 // mt discovery
2318 MAX2((int)ParallelGCThreads, 1),
2319 // degree of mt discovery
2320 true,
2321 // Reference discovery is atomic
2322 &_is_alive_closure_stw,
2323 // is alive closure
2324 // (for efficiency/performance)
2325 false);
2326 // Setting next fields of discovered
2327 // lists requires a barrier.
2328 }
2329
2330 size_t G1CollectedHeap::capacity() const {
2331 return _g1_committed.byte_size();
2332 }
2333
2334 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2335 assert(!hr->continuesHumongous(), "pre-condition");
2336 hr->reset_gc_time_stamp();
2337 if (hr->startsHumongous()) {
2338 uint first_index = hr->hrs_index() + 1;
2339 uint last_index = hr->last_hc_index();
2340 for (uint i = first_index; i < last_index; i += 1) {
2341 HeapRegion* chr = region_at(i);
2342 assert(chr->continuesHumongous(), "sanity");
2343 chr->reset_gc_time_stamp();
2344 }
2345 }
2346 }
2347
2348 #ifndef PRODUCT
2349 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2350 private:
2351 unsigned _gc_time_stamp;
2352 bool _failures;
2353
2354 public:
2355 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2356 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2357
2358 virtual bool doHeapRegion(HeapRegion* hr) {
2359 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2360 if (_gc_time_stamp != region_gc_time_stamp) {
2361 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2362 "expected %d", HR_FORMAT_PARAMS(hr),
2363 region_gc_time_stamp, _gc_time_stamp);
2364 _failures = true;
2365 }
2366 return false;
2367 }
2368
2369 bool failures() { return _failures; }
2370 };
2371
2372 void G1CollectedHeap::check_gc_time_stamps() {
2373 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2374 heap_region_iterate(&cl);
2375 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2376 }
2377 #endif // PRODUCT
2378
2379 int G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2380 CardTableEntryClosure* cleaned_cl,
2381 DirtyCardQueue* into_cset_dcq,
2382 bool concurrent,
2383 int worker_i) {
2384 // Clean cards in the hot card cache
2385 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2386 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2387
2388 int n_completed_buffers = 0;
2389 if (worker_i == 0) {
2390 concurrent_g1_refine()->flush_cards_in_buffers();
2391 }
2392 DirtyCardQueueSet& refinement_dcqs = concurrent_g1_refine()->cards_ready_for_refinement();
2393 while (refinement_dcqs.apply_closure_to_completed_buffer(cleaned_cl, worker_i, 0, true)) {
2394 n_completed_buffers++;
2395 }
2396
2397 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2398 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2399 n_completed_buffers++;
2400 }
2401
2402 dcqs.clear_n_completed_buffers();
2403 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2404 return n_completed_buffers;
2405 }
2406
2407
2408 // Computes the sum of the storage used by the various regions.
2409
2410 size_t G1CollectedHeap::used() const {
2411 assert(Heap_lock->owner() != NULL,
2412 "Should be owned on this thread's behalf.");
2413 size_t result = _summary_bytes_used;
2414 // Read only once in case it is set to NULL concurrently
2415 HeapRegion* hr = _mutator_alloc_region.get();
2416 if (hr != NULL)
2417 result += hr->used();
2418 return result;
2419 }
2420
2421 size_t G1CollectedHeap::used_unlocked() const {
2422 size_t result = _summary_bytes_used;
2423 return result;
2424 }
2425
2426 class SumUsedClosure: public HeapRegionClosure {
2427 size_t _used;
2428 public:
2429 SumUsedClosure() : _used(0) {}
2430 bool doHeapRegion(HeapRegion* r) {
2431 if (!r->continuesHumongous()) {
2432 _used += r->used();
2433 }
2434 return false;
2435 }
2436 size_t result() { return _used; }
2437 };
2438
2439 size_t G1CollectedHeap::recalculate_used() const {
2440 SumUsedClosure blk;
2441 heap_region_iterate(&blk);
2442 return blk.result();
2443 }
2444
2445 size_t G1CollectedHeap::unsafe_max_alloc() {
2446 if (free_regions() > 0) return HeapRegion::GrainBytes;
2447 // otherwise, is there space in the current allocation region?
2448
2449 // We need to store the current allocation region in a local variable
2450 // here. The problem is that this method doesn't take any locks and
2451 // there may be other threads which overwrite the current allocation
2452 // region field. attempt_allocation(), for example, sets it to NULL
2453 // and this can happen *after* the NULL check here but before the call
2454 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2455 // to be a problem in the optimized build, since the two loads of the
2456 // current allocation region field are optimized away.
2457 HeapRegion* hr = _mutator_alloc_region.get();
2458 if (hr == NULL) {
2459 return 0;
2460 }
2461 return hr->free();
2462 }
2463
2464 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2465 switch (cause) {
2466 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2467 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2468 case GCCause::_g1_humongous_allocation: return true;
2469 default: return false;
2470 }
2471 }
2472
2473 #ifndef PRODUCT
2474 void G1CollectedHeap::allocate_dummy_regions() {
2475 // Let's fill up most of the region
2476 size_t word_size = HeapRegion::GrainWords - 1024;
2477 // And as a result the region we'll allocate will be humongous.
2478 guarantee(isHumongous(word_size), "sanity");
2479
2480 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2481 // Let's use the existing mechanism for the allocation
2482 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2483 if (dummy_obj != NULL) {
2484 MemRegion mr(dummy_obj, word_size);
2485 CollectedHeap::fill_with_object(mr);
2486 } else {
2487 // If we can't allocate once, we probably cannot allocate
2488 // again. Let's get out of the loop.
2489 break;
2490 }
2491 }
2492 }
2493 #endif // !PRODUCT
2494
2495 void G1CollectedHeap::increment_old_marking_cycles_started() {
2496 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2497 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2498 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2499 _old_marking_cycles_started, _old_marking_cycles_completed));
2500
2501 _old_marking_cycles_started++;
2502 }
2503
2504 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2505 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2506
2507 // We assume that if concurrent == true, then the caller is a
2508 // concurrent thread that was joined the Suspendible Thread
2509 // Set. If there's ever a cheap way to check this, we should add an
2510 // assert here.
2511
2512 // Given that this method is called at the end of a Full GC or of a
2513 // concurrent cycle, and those can be nested (i.e., a Full GC can
2514 // interrupt a concurrent cycle), the number of full collections
2515 // completed should be either one (in the case where there was no
2516 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2517 // behind the number of full collections started.
2518
2519 // This is the case for the inner caller, i.e. a Full GC.
2520 assert(concurrent ||
2521 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2522 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2523 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2524 "is inconsistent with _old_marking_cycles_completed = %u",
2525 _old_marking_cycles_started, _old_marking_cycles_completed));
2526
2527 // This is the case for the outer caller, i.e. the concurrent cycle.
2528 assert(!concurrent ||
2529 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2530 err_msg("for outer caller (concurrent cycle): "
2531 "_old_marking_cycles_started = %u "
2532 "is inconsistent with _old_marking_cycles_completed = %u",
2533 _old_marking_cycles_started, _old_marking_cycles_completed));
2534
2535 _old_marking_cycles_completed += 1;
2536
2537 // We need to clear the "in_progress" flag in the CM thread before
2538 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2539 // is set) so that if a waiter requests another System.gc() it doesn't
2540 // incorrectly see that a marking cycle is still in progress.
2541 if (concurrent) {
2542 _cmThread->clear_in_progress();
2543 }
2544
2545 // This notify_all() will ensure that a thread that called
2546 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2547 // and it's waiting for a full GC to finish will be woken up. It is
2548 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2549 FullGCCount_lock->notify_all();
2550 }
2551
2552 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2553 _concurrent_cycle_started = true;
2554 _gc_timer_cm->register_gc_start(start_time);
2555
2556 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2557 trace_heap_before_gc(_gc_tracer_cm);
2558 }
2559
2560 void G1CollectedHeap::register_concurrent_cycle_end() {
2561 if (_concurrent_cycle_started) {
2562 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2563
2564 if (_cm->has_aborted()) {
2565 _gc_tracer_cm->report_concurrent_mode_failure();
2566 }
2567 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2568
2569 _concurrent_cycle_started = false;
2570 }
2571 }
2572
2573 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2574 if (_concurrent_cycle_started) {
2575 trace_heap_after_gc(_gc_tracer_cm);
2576 }
2577 }
2578
2579 G1YCType G1CollectedHeap::yc_type() {
2580 bool is_young = g1_policy()->gcs_are_young();
2581 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2582 bool is_during_mark = mark_in_progress();
2583
2584 if (is_initial_mark) {
2585 return InitialMark;
2586 } else if (is_during_mark) {
2587 return DuringMark;
2588 } else if (is_young) {
2589 return Normal;
2590 } else {
2591 return Mixed;
2592 }
2593 }
2594
2595 void G1CollectedHeap::collect(GCCause::Cause cause) {
2596 assert_heap_not_locked();
2597
2598 unsigned int gc_count_before;
2599 unsigned int old_marking_count_before;
2600 bool retry_gc;
2601
2602 do {
2603 retry_gc = false;
2604
2605 {
2606 MutexLocker ml(Heap_lock);
2607
2608 // Read the GC count while holding the Heap_lock
2609 gc_count_before = total_collections();
2610 old_marking_count_before = _old_marking_cycles_started;
2611 }
2612
2613 if (should_do_concurrent_full_gc(cause)) {
2614 // Schedule an initial-mark evacuation pause that will start a
2615 // concurrent cycle. We're setting word_size to 0 which means that
2616 // we are not requesting a post-GC allocation.
2617 VM_G1IncCollectionPause op(gc_count_before,
2618 0, /* word_size */
2619 true, /* should_initiate_conc_mark */
2620 g1_policy()->max_pause_time_ms(),
2621 cause);
2622
2623 VMThread::execute(&op);
2624 if (!op.pause_succeeded()) {
2625 if (old_marking_count_before == _old_marking_cycles_started) {
2626 retry_gc = op.should_retry_gc();
2627 } else {
2628 // A Full GC happened while we were trying to schedule the
2629 // initial-mark GC. No point in starting a new cycle given
2630 // that the whole heap was collected anyway.
2631 }
2632
2633 if (retry_gc) {
2634 if (GC_locker::is_active_and_needs_gc()) {
2635 GC_locker::stall_until_clear();
2636 }
2637 }
2638 }
2639 } else {
2640 if (cause == GCCause::_gc_locker
2641 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2642
2643 // Schedule a standard evacuation pause. We're setting word_size
2644 // to 0 which means that we are not requesting a post-GC allocation.
2645 VM_G1IncCollectionPause op(gc_count_before,
2646 0, /* word_size */
2647 false, /* should_initiate_conc_mark */
2648 g1_policy()->max_pause_time_ms(),
2649 cause);
2650 VMThread::execute(&op);
2651 } else {
2652 // Schedule a Full GC.
2653 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2654 VMThread::execute(&op);
2655 }
2656 }
2657 } while (retry_gc);
2658 }
2659
2660 bool G1CollectedHeap::is_in(const void* p) const {
2661 if (_g1_committed.contains(p)) {
2662 // Given that we know that p is in the committed space,
2663 // heap_region_containing_raw() should successfully
2664 // return the containing region.
2665 HeapRegion* hr = heap_region_containing_raw(p);
2666 return hr->is_in(p);
2667 } else {
2668 return false;
2669 }
2670 }
2671
2672 // Iteration functions.
2673
2674 // Iterates an OopClosure over all ref-containing fields of objects
2675 // within a HeapRegion.
2676
2677 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2678 MemRegion _mr;
2679 ExtendedOopClosure* _cl;
2680 public:
2681 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2682 : _mr(mr), _cl(cl) {}
2683 bool doHeapRegion(HeapRegion* r) {
2684 if (!r->continuesHumongous()) {
2685 r->oop_iterate(_cl);
2686 }
2687 return false;
2688 }
2689 };
2690
2691 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2692 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2693 heap_region_iterate(&blk);
2694 }
2695
2696 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2697 IterateOopClosureRegionClosure blk(mr, cl);
2698 heap_region_iterate(&blk);
2699 }
2700
2701 // Iterates an ObjectClosure over all objects within a HeapRegion.
2702
2703 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2704 ObjectClosure* _cl;
2705 public:
2706 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2707 bool doHeapRegion(HeapRegion* r) {
2708 if (! r->continuesHumongous()) {
2709 r->object_iterate(_cl);
2710 }
2711 return false;
2712 }
2713 };
2714
2715 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2716 IterateObjectClosureRegionClosure blk(cl);
2717 heap_region_iterate(&blk);
2718 }
2719
2720 // Calls a SpaceClosure on a HeapRegion.
2721
2722 class SpaceClosureRegionClosure: public HeapRegionClosure {
2723 SpaceClosure* _cl;
2724 public:
2725 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2726 bool doHeapRegion(HeapRegion* r) {
2727 _cl->do_space(r);
2728 return false;
2729 }
2730 };
2731
2732 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2733 SpaceClosureRegionClosure blk(cl);
2734 heap_region_iterate(&blk);
2735 }
2736
2737 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2738 _hrs.iterate(cl);
2739 }
2740
2741 void
2742 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2743 uint worker_id,
2744 uint no_of_par_workers,
2745 jint claim_value) {
2746 const uint regions = n_regions();
2747 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2748 no_of_par_workers :
2749 1);
2750 assert(UseDynamicNumberOfGCThreads ||
2751 no_of_par_workers == workers()->total_workers(),
2752 "Non dynamic should use fixed number of workers");
2753 // try to spread out the starting points of the workers
2754 const HeapRegion* start_hr =
2755 start_region_for_worker(worker_id, no_of_par_workers);
2756 const uint start_index = start_hr->hrs_index();
2757
2758 // each worker will actually look at all regions
2759 for (uint count = 0; count < regions; ++count) {
2760 const uint index = (start_index + count) % regions;
2761 assert(0 <= index && index < regions, "sanity");
2762 HeapRegion* r = region_at(index);
2763 // we'll ignore "continues humongous" regions (we'll process them
2764 // when we come across their corresponding "start humongous"
2765 // region) and regions already claimed
2766 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2767 continue;
2768 }
2769 // OK, try to claim it
2770 if (r->claimHeapRegion(claim_value)) {
2771 // success!
2772 assert(!r->continuesHumongous(), "sanity");
2773 if (r->startsHumongous()) {
2774 // If the region is "starts humongous" we'll iterate over its
2775 // "continues humongous" first; in fact we'll do them
2776 // first. The order is important. In on case, calling the
2777 // closure on the "starts humongous" region might de-allocate
2778 // and clear all its "continues humongous" regions and, as a
2779 // result, we might end up processing them twice. So, we'll do
2780 // them first (notice: most closures will ignore them anyway) and
2781 // then we'll do the "starts humongous" region.
2782 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2783 HeapRegion* chr = region_at(ch_index);
2784
2785 // if the region has already been claimed or it's not
2786 // "continues humongous" we're done
2787 if (chr->claim_value() == claim_value ||
2788 !chr->continuesHumongous()) {
2789 break;
2790 }
2791
2792 // No one should have claimed it directly. We can given
2793 // that we claimed its "starts humongous" region.
2794 assert(chr->claim_value() != claim_value, "sanity");
2795 assert(chr->humongous_start_region() == r, "sanity");
2796
2797 if (chr->claimHeapRegion(claim_value)) {
2798 // we should always be able to claim it; no one else should
2799 // be trying to claim this region
2800
2801 bool res2 = cl->doHeapRegion(chr);
2802 assert(!res2, "Should not abort");
2803
2804 // Right now, this holds (i.e., no closure that actually
2805 // does something with "continues humongous" regions
2806 // clears them). We might have to weaken it in the future,
2807 // but let's leave these two asserts here for extra safety.
2808 assert(chr->continuesHumongous(), "should still be the case");
2809 assert(chr->humongous_start_region() == r, "sanity");
2810 } else {
2811 guarantee(false, "we should not reach here");
2812 }
2813 }
2814 }
2815
2816 assert(!r->continuesHumongous(), "sanity");
2817 bool res = cl->doHeapRegion(r);
2818 assert(!res, "Should not abort");
2819 }
2820 }
2821 }
2822
2823 class ResetClaimValuesClosure: public HeapRegionClosure {
2824 public:
2825 bool doHeapRegion(HeapRegion* r) {
2826 r->set_claim_value(HeapRegion::InitialClaimValue);
2827 return false;
2828 }
2829 };
2830
2831 void G1CollectedHeap::reset_heap_region_claim_values() {
2832 ResetClaimValuesClosure blk;
2833 heap_region_iterate(&blk);
2834 }
2835
2836 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2837 ResetClaimValuesClosure blk;
2838 collection_set_iterate(&blk);
2839 }
2840
2841 #ifdef ASSERT
2842 // This checks whether all regions in the heap have the correct claim
2843 // value. I also piggy-backed on this a check to ensure that the
2844 // humongous_start_region() information on "continues humongous"
2845 // regions is correct.
2846
2847 class CheckClaimValuesClosure : public HeapRegionClosure {
2848 private:
2849 jint _claim_value;
2850 uint _failures;
2851 HeapRegion* _sh_region;
2852
2853 public:
2854 CheckClaimValuesClosure(jint claim_value) :
2855 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2856 bool doHeapRegion(HeapRegion* r) {
2857 if (r->claim_value() != _claim_value) {
2858 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2859 "claim value = %d, should be %d",
2860 HR_FORMAT_PARAMS(r),
2861 r->claim_value(), _claim_value);
2862 ++_failures;
2863 }
2864 if (!r->isHumongous()) {
2865 _sh_region = NULL;
2866 } else if (r->startsHumongous()) {
2867 _sh_region = r;
2868 } else if (r->continuesHumongous()) {
2869 if (r->humongous_start_region() != _sh_region) {
2870 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2871 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2872 HR_FORMAT_PARAMS(r),
2873 r->humongous_start_region(),
2874 _sh_region);
2875 ++_failures;
2876 }
2877 }
2878 return false;
2879 }
2880 uint failures() { return _failures; }
2881 };
2882
2883 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2884 CheckClaimValuesClosure cl(claim_value);
2885 heap_region_iterate(&cl);
2886 return cl.failures() == 0;
2887 }
2888
2889 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2890 private:
2891 jint _claim_value;
2892 uint _failures;
2893
2894 public:
2895 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2896 _claim_value(claim_value), _failures(0) { }
2897
2898 uint failures() { return _failures; }
2899
2900 bool doHeapRegion(HeapRegion* hr) {
2901 assert(hr->in_collection_set(), "how?");
2902 assert(!hr->isHumongous(), "H-region in CSet");
2903 if (hr->claim_value() != _claim_value) {
2904 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2905 "claim value = %d, should be %d",
2906 HR_FORMAT_PARAMS(hr),
2907 hr->claim_value(), _claim_value);
2908 _failures += 1;
2909 }
2910 return false;
2911 }
2912 };
2913
2914 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2915 CheckClaimValuesInCSetHRClosure cl(claim_value);
2916 collection_set_iterate(&cl);
2917 return cl.failures() == 0;
2918 }
2919 #endif // ASSERT
2920
2921 // Clear the cached CSet starting regions and (more importantly)
2922 // the time stamps. Called when we reset the GC time stamp.
2923 void G1CollectedHeap::clear_cset_start_regions() {
2924 assert(_worker_cset_start_region != NULL, "sanity");
2925 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2926
2927 int n_queues = MAX2((int)ParallelGCThreads, 1);
2928 for (int i = 0; i < n_queues; i++) {
2929 _worker_cset_start_region[i] = NULL;
2930 _worker_cset_start_region_time_stamp[i] = 0;
2931 }
2932 }
2933
2934 // Given the id of a worker, obtain or calculate a suitable
2935 // starting region for iterating over the current collection set.
2936 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2937 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2938
2939 HeapRegion* result = NULL;
2940 unsigned gc_time_stamp = get_gc_time_stamp();
2941
2942 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2943 // Cached starting region for current worker was set
2944 // during the current pause - so it's valid.
2945 // Note: the cached starting heap region may be NULL
2946 // (when the collection set is empty).
2947 result = _worker_cset_start_region[worker_i];
2948 assert(result == NULL || result->in_collection_set(), "sanity");
2949 return result;
2950 }
2951
2952 // The cached entry was not valid so let's calculate
2953 // a suitable starting heap region for this worker.
2954
2955 // We want the parallel threads to start their collection
2956 // set iteration at different collection set regions to
2957 // avoid contention.
2958 // If we have:
2959 // n collection set regions
2960 // p threads
2961 // Then thread t will start at region floor ((t * n) / p)
2962
2963 result = g1_policy()->collection_set();
2964 if (G1CollectedHeap::use_parallel_gc_threads()) {
2965 uint cs_size = g1_policy()->cset_region_length();
2966 uint active_workers = workers()->active_workers();
2967 assert(UseDynamicNumberOfGCThreads ||
2968 active_workers == workers()->total_workers(),
2969 "Unless dynamic should use total workers");
2970
2971 uint end_ind = (cs_size * worker_i) / active_workers;
2972 uint start_ind = 0;
2973
2974 if (worker_i > 0 &&
2975 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2976 // Previous workers starting region is valid
2977 // so let's iterate from there
2978 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2979 result = _worker_cset_start_region[worker_i - 1];
2980 }
2981
2982 for (uint i = start_ind; i < end_ind; i++) {
2983 result = result->next_in_collection_set();
2984 }
2985 }
2986
2987 // Note: the calculated starting heap region may be NULL
2988 // (when the collection set is empty).
2989 assert(result == NULL || result->in_collection_set(), "sanity");
2990 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2991 "should be updated only once per pause");
2992 _worker_cset_start_region[worker_i] = result;
2993 OrderAccess::storestore();
2994 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2995 return result;
2996 }
2997
2998 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2999 uint no_of_par_workers) {
3000 uint worker_num =
3001 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
3002 assert(UseDynamicNumberOfGCThreads ||
3003 no_of_par_workers == workers()->total_workers(),
3004 "Non dynamic should use fixed number of workers");
3005 const uint start_index = n_regions() * worker_i / worker_num;
3006 return region_at(start_index);
3007 }
3008
3009 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
3010 HeapRegion* r = g1_policy()->collection_set();
3011 while (r != NULL) {
3012 HeapRegion* next = r->next_in_collection_set();
3013 if (cl->doHeapRegion(r)) {
3014 cl->incomplete();
3015 return;
3016 }
3017 r = next;
3018 }
3019 }
3020
3021 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
3022 HeapRegionClosure *cl) {
3023 if (r == NULL) {
3024 // The CSet is empty so there's nothing to do.
3025 return;
3026 }
3027
3028 assert(r->in_collection_set(),
3029 "Start region must be a member of the collection set.");
3030 HeapRegion* cur = r;
3031 while (cur != NULL) {
3032 HeapRegion* next = cur->next_in_collection_set();
3033 if (cl->doHeapRegion(cur) && false) {
3034 cl->incomplete();
3035 return;
3036 }
3037 cur = next;
3038 }
3039 cur = g1_policy()->collection_set();
3040 while (cur != r) {
3041 HeapRegion* next = cur->next_in_collection_set();
3042 if (cl->doHeapRegion(cur) && false) {
3043 cl->incomplete();
3044 return;
3045 }
3046 cur = next;
3047 }
3048 }
3049
3050 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
3051 return n_regions() > 0 ? region_at(0) : NULL;
3052 }
3053
3054
3055 Space* G1CollectedHeap::space_containing(const void* addr) const {
3056 Space* res = heap_region_containing(addr);
3057 return res;
3058 }
3059
3060 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
3061 Space* sp = space_containing(addr);
3062 if (sp != NULL) {
3063 return sp->block_start(addr);
3064 }
3065 return NULL;
3066 }
3067
3068 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3069 Space* sp = space_containing(addr);
3070 assert(sp != NULL, "block_size of address outside of heap");
3071 return sp->block_size(addr);
3072 }
3073
3074 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3075 Space* sp = space_containing(addr);
3076 return sp->block_is_obj(addr);
3077 }
3078
3079 bool G1CollectedHeap::supports_tlab_allocation() const {
3080 return true;
3081 }
3082
3083 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3084 return HeapRegion::GrainBytes;
3085 }
3086
3087 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3088 // Return the remaining space in the cur alloc region, but not less than
3089 // the min TLAB size.
3090
3091 // Also, this value can be at most the humongous object threshold,
3092 // since we can't allow tlabs to grow big enough to accommodate
3093 // humongous objects.
3094
3095 HeapRegion* hr = _mutator_alloc_region.get();
3096 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3097 if (hr == NULL) {
3098 return max_tlab_size;
3099 } else {
3100 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3101 }
3102 }
3103
3104 void G1CollectedHeap::inform_non_gc_safepoint() {
3105 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3106 while (dcqs.apply_closure_to_completed_buffer(0, 0, true));
3107 }
3108
3109 size_t G1CollectedHeap::max_capacity() const {
3110 return _g1_reserved.byte_size();
3111 }
3112
3113 jlong G1CollectedHeap::millis_since_last_gc() {
3114 // assert(false, "NYI");
3115 return 0;
3116 }
3117
3118 void G1CollectedHeap::prepare_for_verify() {
3119 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3120 ensure_parsability(false);
3121 }
3122 g1_rem_set()->prepare_for_verify();
3123 }
3124
3125 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3126 VerifyOption vo) {
3127 switch (vo) {
3128 case VerifyOption_G1UsePrevMarking:
3129 return hr->obj_allocated_since_prev_marking(obj);
3130 case VerifyOption_G1UseNextMarking:
3131 return hr->obj_allocated_since_next_marking(obj);
3132 case VerifyOption_G1UseMarkWord:
3133 return false;
3134 default:
3135 ShouldNotReachHere();
3136 }
3137 return false; // keep some compilers happy
3138 }
3139
3140 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3141 switch (vo) {
3142 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3143 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3144 case VerifyOption_G1UseMarkWord: return NULL;
3145 default: ShouldNotReachHere();
3146 }
3147 return NULL; // keep some compilers happy
3148 }
3149
3150 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3151 switch (vo) {
3152 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3153 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3154 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3155 default: ShouldNotReachHere();
3156 }
3157 return false; // keep some compilers happy
3158 }
3159
3160 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3161 switch (vo) {
3162 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3163 case VerifyOption_G1UseNextMarking: return "NTAMS";
3164 case VerifyOption_G1UseMarkWord: return "NONE";
3165 default: ShouldNotReachHere();
3166 }
3167 return NULL; // keep some compilers happy
3168 }
3169
3170 class VerifyLivenessOopClosure: public OopClosure {
3171 G1CollectedHeap* _g1h;
3172 VerifyOption _vo;
3173 public:
3174 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3175 _g1h(g1h), _vo(vo)
3176 { }
3177 void do_oop(narrowOop *p) { do_oop_work(p); }
3178 void do_oop( oop *p) { do_oop_work(p); }
3179
3180 template <class T> void do_oop_work(T *p) {
3181 oop obj = oopDesc::load_decode_heap_oop(p);
3182 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3183 "Dead object referenced by a not dead object");
3184 }
3185 };
3186
3187 class VerifyObjsInRegionClosure: public ObjectClosure {
3188 private:
3189 G1CollectedHeap* _g1h;
3190 size_t _live_bytes;
3191 HeapRegion *_hr;
3192 VerifyOption _vo;
3193 public:
3194 // _vo == UsePrevMarking -> use "prev" marking information,
3195 // _vo == UseNextMarking -> use "next" marking information,
3196 // _vo == UseMarkWord -> use mark word from object header.
3197 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3198 : _live_bytes(0), _hr(hr), _vo(vo) {
3199 _g1h = G1CollectedHeap::heap();
3200 }
3201 void do_object(oop o) {
3202 VerifyLivenessOopClosure isLive(_g1h, _vo);
3203 assert(o != NULL, "Huh?");
3204 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3205 // If the object is alive according to the mark word,
3206 // then verify that the marking information agrees.
3207 // Note we can't verify the contra-positive of the
3208 // above: if the object is dead (according to the mark
3209 // word), it may not be marked, or may have been marked
3210 // but has since became dead, or may have been allocated
3211 // since the last marking.
3212 if (_vo == VerifyOption_G1UseMarkWord) {
3213 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3214 }
3215
3216 o->oop_iterate_no_header(&isLive);
3217 if (!_hr->obj_allocated_since_prev_marking(o)) {
3218 size_t obj_size = o->size(); // Make sure we don't overflow
3219 _live_bytes += (obj_size * HeapWordSize);
3220 }
3221 }
3222 }
3223 size_t live_bytes() { return _live_bytes; }
3224 };
3225
3226 class PrintObjsInRegionClosure : public ObjectClosure {
3227 HeapRegion *_hr;
3228 G1CollectedHeap *_g1;
3229 public:
3230 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3231 _g1 = G1CollectedHeap::heap();
3232 };
3233
3234 void do_object(oop o) {
3235 if (o != NULL) {
3236 HeapWord *start = (HeapWord *) o;
3237 size_t word_sz = o->size();
3238 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3239 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3240 (void*) o, word_sz,
3241 _g1->isMarkedPrev(o),
3242 _g1->isMarkedNext(o),
3243 _hr->obj_allocated_since_prev_marking(o));
3244 HeapWord *end = start + word_sz;
3245 HeapWord *cur;
3246 int *val;
3247 for (cur = start; cur < end; cur++) {
3248 val = (int *) cur;
3249 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3250 }
3251 }
3252 }
3253 };
3254
3255 class VerifyRegionClosure: public HeapRegionClosure {
3256 private:
3257 bool _par;
3258 VerifyOption _vo;
3259 bool _failures;
3260 public:
3261 // _vo == UsePrevMarking -> use "prev" marking information,
3262 // _vo == UseNextMarking -> use "next" marking information,
3263 // _vo == UseMarkWord -> use mark word from object header.
3264 VerifyRegionClosure(bool par, VerifyOption vo)
3265 : _par(par),
3266 _vo(vo),
3267 _failures(false) {}
3268
3269 bool failures() {
3270 return _failures;
3271 }
3272
3273 bool doHeapRegion(HeapRegion* r) {
3274 if (!r->continuesHumongous()) {
3275 bool failures = false;
3276 r->verify(_vo, &failures);
3277 if (failures) {
3278 _failures = true;
3279 } else {
3280 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3281 r->object_iterate(¬_dead_yet_cl);
3282 if (_vo != VerifyOption_G1UseNextMarking) {
3283 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3284 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3285 "max_live_bytes "SIZE_FORMAT" "
3286 "< calculated "SIZE_FORMAT,
3287 r->bottom(), r->end(),
3288 r->max_live_bytes(),
3289 not_dead_yet_cl.live_bytes());
3290 _failures = true;
3291 }
3292 } else {
3293 // When vo == UseNextMarking we cannot currently do a sanity
3294 // check on the live bytes as the calculation has not been
3295 // finalized yet.
3296 }
3297 }
3298 }
3299 return false; // stop the region iteration if we hit a failure
3300 }
3301 };
3302
3303 class YoungRefCounterClosure : public OopClosure {
3304 G1CollectedHeap* _g1h;
3305 int _count;
3306 public:
3307 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3308 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3309 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3310
3311 int count() { return _count; }
3312 void reset_count() { _count = 0; };
3313 };
3314
3315 class VerifyKlassClosure: public KlassClosure {
3316 YoungRefCounterClosure _young_ref_counter_closure;
3317 OopClosure *_oop_closure;
3318 public:
3319 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3320 void do_klass(Klass* k) {
3321 k->oops_do(_oop_closure);
3322
3323 _young_ref_counter_closure.reset_count();
3324 k->oops_do(&_young_ref_counter_closure);
3325 if (_young_ref_counter_closure.count() > 0) {
3326 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3327 }
3328 }
3329 };
3330
3331 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3332 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3333 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3334 // we can change this closure to extend the simpler OopClosure.
3335 class VerifyRootsClosure: public OopsInGenClosure {
3336 private:
3337 G1CollectedHeap* _g1h;
3338 VerifyOption _vo;
3339 bool _failures;
3340 public:
3341 // _vo == UsePrevMarking -> use "prev" marking information,
3342 // _vo == UseNextMarking -> use "next" marking information,
3343 // _vo == UseMarkWord -> use mark word from object header.
3344 VerifyRootsClosure(VerifyOption vo) :
3345 _g1h(G1CollectedHeap::heap()),
3346 _vo(vo),
3347 _failures(false) { }
3348
3349 bool failures() { return _failures; }
3350
3351 template <class T> void do_oop_nv(T* p) {
3352 T heap_oop = oopDesc::load_heap_oop(p);
3353 if (!oopDesc::is_null(heap_oop)) {
3354 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3355 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3356 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3357 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3358 if (_vo == VerifyOption_G1UseMarkWord) {
3359 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3360 }
3361 obj->print_on(gclog_or_tty);
3362 _failures = true;
3363 }
3364 }
3365 }
3366
3367 void do_oop(oop* p) { do_oop_nv(p); }
3368 void do_oop(narrowOop* p) { do_oop_nv(p); }
3369 };
3370
3371 // This is the task used for parallel heap verification.
3372
3373 class G1ParVerifyTask: public AbstractGangTask {
3374 private:
3375 G1CollectedHeap* _g1h;
3376 VerifyOption _vo;
3377 bool _failures;
3378
3379 public:
3380 // _vo == UsePrevMarking -> use "prev" marking information,
3381 // _vo == UseNextMarking -> use "next" marking information,
3382 // _vo == UseMarkWord -> use mark word from object header.
3383 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3384 AbstractGangTask("Parallel verify task"),
3385 _g1h(g1h),
3386 _vo(vo),
3387 _failures(false) { }
3388
3389 bool failures() {
3390 return _failures;
3391 }
3392
3393 void work(uint worker_id) {
3394 HandleMark hm;
3395 VerifyRegionClosure blk(true, _vo);
3396 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3397 _g1h->workers()->active_workers(),
3398 HeapRegion::ParVerifyClaimValue);
3399 if (blk.failures()) {
3400 _failures = true;
3401 }
3402 }
3403 };
3404
3405 void G1CollectedHeap::verify(bool silent) {
3406 verify(silent, VerifyOption_G1UsePrevMarking);
3407 }
3408
3409 void G1CollectedHeap::verify(bool silent,
3410 VerifyOption vo) {
3411 if (SafepointSynchronize::is_at_safepoint()) {
3412 if (!silent) { gclog_or_tty->print("Roots "); }
3413 VerifyRootsClosure rootsCl(vo);
3414
3415 assert(Thread::current()->is_VM_thread(),
3416 "Expected to be executed serially by the VM thread at this point");
3417
3418 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3419 VerifyKlassClosure klassCl(this, &rootsCl);
3420
3421 // We apply the relevant closures to all the oops in the
3422 // system dictionary, the string table and the code cache.
3423 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3424
3425 // Need cleared claim bits for the strong roots processing
3426 ClassLoaderDataGraph::clear_claimed_marks();
3427
3428 process_strong_roots(true, // activate StrongRootsScope
3429 false, // we set "is scavenging" to false,
3430 // so we don't reset the dirty cards.
3431 ScanningOption(so), // roots scanning options
3432 &rootsCl,
3433 &blobsCl,
3434 &klassCl
3435 );
3436
3437 bool failures = rootsCl.failures();
3438
3439 if (vo != VerifyOption_G1UseMarkWord) {
3440 // If we're verifying during a full GC then the region sets
3441 // will have been torn down at the start of the GC. Therefore
3442 // verifying the region sets will fail. So we only verify
3443 // the region sets when not in a full GC.
3444 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3445 verify_region_sets();
3446 }
3447
3448 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3449 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3450 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3451 "sanity check");
3452
3453 G1ParVerifyTask task(this, vo);
3454 assert(UseDynamicNumberOfGCThreads ||
3455 workers()->active_workers() == workers()->total_workers(),
3456 "If not dynamic should be using all the workers");
3457 int n_workers = workers()->active_workers();
3458 set_par_threads(n_workers);
3459 workers()->run_task(&task);
3460 set_par_threads(0);
3461 if (task.failures()) {
3462 failures = true;
3463 }
3464
3465 // Checks that the expected amount of parallel work was done.
3466 // The implication is that n_workers is > 0.
3467 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3468 "sanity check");
3469
3470 reset_heap_region_claim_values();
3471
3472 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3473 "sanity check");
3474 } else {
3475 VerifyRegionClosure blk(false, vo);
3476 heap_region_iterate(&blk);
3477 if (blk.failures()) {
3478 failures = true;
3479 }
3480 }
3481 if (!silent) gclog_or_tty->print("RemSet ");
3482 rem_set()->verify();
3483
3484 if (failures) {
3485 gclog_or_tty->print_cr("Heap:");
3486 // It helps to have the per-region information in the output to
3487 // help us track down what went wrong. This is why we call
3488 // print_extended_on() instead of print_on().
3489 print_extended_on(gclog_or_tty);
3490 gclog_or_tty->print_cr("");
3491 #ifndef PRODUCT
3492 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3493 concurrent_mark()->print_reachable("at-verification-failure",
3494 vo, false /* all */);
3495 }
3496 #endif
3497 gclog_or_tty->flush();
3498 }
3499 guarantee(!failures, "there should not have been any failures");
3500 } else {
3501 if (!silent)
3502 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3503 }
3504 }
3505
3506 class PrintRegionClosure: public HeapRegionClosure {
3507 outputStream* _st;
3508 public:
3509 PrintRegionClosure(outputStream* st) : _st(st) {}
3510 bool doHeapRegion(HeapRegion* r) {
3511 r->print_on(_st);
3512 return false;
3513 }
3514 };
3515
3516 void G1CollectedHeap::print_on(outputStream* st) const {
3517 st->print(" %-20s", "garbage-first heap");
3518 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3519 capacity()/K, used_unlocked()/K);
3520 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3521 _g1_storage.low_boundary(),
3522 _g1_storage.high(),
3523 _g1_storage.high_boundary());
3524 st->cr();
3525 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3526 uint young_regions = _young_list->length();
3527 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3528 (size_t) young_regions * HeapRegion::GrainBytes / K);
3529 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3530 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3531 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3532 st->cr();
3533 MetaspaceAux::print_on(st);
3534 }
3535
3536 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3537 print_on(st);
3538
3539 // Print the per-region information.
3540 st->cr();
3541 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3542 "HS=humongous(starts), HC=humongous(continues), "
3543 "CS=collection set, F=free, TS=gc time stamp, "
3544 "PTAMS=previous top-at-mark-start, "
3545 "NTAMS=next top-at-mark-start)");
3546 PrintRegionClosure blk(st);
3547 heap_region_iterate(&blk);
3548 }
3549
3550 void G1CollectedHeap::print_on_error(outputStream* st) const {
3551 this->CollectedHeap::print_on_error(st);
3552
3553 if (_cm != NULL) {
3554 st->cr();
3555 _cm->print_on_error(st);
3556 }
3557 }
3558
3559 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3560 if (G1CollectedHeap::use_parallel_gc_threads()) {
3561 workers()->print_worker_threads_on(st);
3562 }
3563 _cmThread->print_on(st);
3564 st->cr();
3565 _cm->print_worker_threads_on(st);
3566 _cg1r->print_worker_threads_on(st);
3567 }
3568
3569 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3570 if (G1CollectedHeap::use_parallel_gc_threads()) {
3571 workers()->threads_do(tc);
3572 }
3573 tc->do_thread(_cmThread);
3574 _cg1r->threads_do(tc);
3575 }
3576
3577 void G1CollectedHeap::print_tracing_info() const {
3578 // We'll overload this to mean "trace GC pause statistics."
3579 if (TraceGen0Time || TraceGen1Time) {
3580 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3581 // to that.
3582 g1_policy()->print_tracing_info();
3583 }
3584 if (G1SummarizeRSetStats) {
3585 g1_rem_set()->print_summary_info();
3586 }
3587 if (G1SummarizeConcMark) {
3588 concurrent_mark()->print_summary_info();
3589 }
3590 g1_policy()->print_yg_surv_rate_info();
3591 SpecializationStats::print();
3592 }
3593
3594 #ifndef PRODUCT
3595 // Helpful for debugging RSet issues.
3596
3597 class PrintRSetsClosure : public HeapRegionClosure {
3598 private:
3599 const char* _msg;
3600 size_t _occupied_sum;
3601
3602 public:
3603 bool doHeapRegion(HeapRegion* r) {
3604 HeapRegionRemSet* hrrs = r->rem_set();
3605 size_t occupied = hrrs->occupied();
3606 _occupied_sum += occupied;
3607
3608 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3609 HR_FORMAT_PARAMS(r));
3610 if (occupied == 0) {
3611 gclog_or_tty->print_cr(" RSet is empty");
3612 } else {
3613 hrrs->print();
3614 }
3615 gclog_or_tty->print_cr("----------");
3616 return false;
3617 }
3618
3619 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3620 gclog_or_tty->cr();
3621 gclog_or_tty->print_cr("========================================");
3622 gclog_or_tty->print_cr(msg);
3623 gclog_or_tty->cr();
3624 }
3625
3626 ~PrintRSetsClosure() {
3627 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3628 gclog_or_tty->print_cr("========================================");
3629 gclog_or_tty->cr();
3630 }
3631 };
3632
3633 void G1CollectedHeap::print_cset_rsets() {
3634 PrintRSetsClosure cl("Printing CSet RSets");
3635 collection_set_iterate(&cl);
3636 }
3637
3638 void G1CollectedHeap::print_all_rsets() {
3639 PrintRSetsClosure cl("Printing All RSets");;
3640 heap_region_iterate(&cl);
3641 }
3642 #endif // PRODUCT
3643
3644 G1CollectedHeap* G1CollectedHeap::heap() {
3645 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3646 "not a garbage-first heap");
3647 return _g1h;
3648 }
3649
3650 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3651 // always_do_update_barrier = false;
3652 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3653 // Fill TLAB's and such
3654 ensure_parsability(true);
3655 }
3656
3657 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3658
3659 if (G1SummarizeRSetStats &&
3660 (G1SummarizeRSetStatsPeriod > 0) &&
3661 // we are at the end of the GC. Total collections has already been increased.
3662 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3663 g1_rem_set()->print_periodic_summary_info();
3664 }
3665
3666 // FIXME: what is this about?
3667 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3668 // is set.
3669 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3670 "derived pointer present"));
3671 // always_do_update_barrier = true;
3672
3673 // We have just completed a GC. Update the soft reference
3674 // policy with the new heap occupancy
3675 Universe::update_heap_info_at_gc();
3676 }
3677
3678 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3679 unsigned int gc_count_before,
3680 bool* succeeded) {
3681 assert_heap_not_locked_and_not_at_safepoint();
3682 g1_policy()->record_stop_world_start();
3683 VM_G1IncCollectionPause op(gc_count_before,
3684 word_size,
3685 false, /* should_initiate_conc_mark */
3686 g1_policy()->max_pause_time_ms(),
3687 GCCause::_g1_inc_collection_pause);
3688 VMThread::execute(&op);
3689
3690 HeapWord* result = op.result();
3691 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3692 assert(result == NULL || ret_succeeded,
3693 "the result should be NULL if the VM did not succeed");
3694 *succeeded = ret_succeeded;
3695
3696 assert_heap_not_locked();
3697 return result;
3698 }
3699
3700 void
3701 G1CollectedHeap::doConcurrentMark() {
3702 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3703 if (!_cmThread->in_progress()) {
3704 _cmThread->set_started();
3705 CGC_lock->notify();
3706 }
3707 }
3708
3709 size_t G1CollectedHeap::pending_card_num() {
3710 size_t extra_cards = 0;
3711 JavaThread *curr = Threads::first();
3712 while (curr != NULL) {
3713 DirtyCardQueue& dcq = curr->dirty_card_queue();
3714 extra_cards += dcq.size();
3715 curr = curr->next();
3716 }
3717 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3718 size_t buffer_size = dcqs.buffer_size();
3719 size_t buffer_num = dcqs.completed_buffers_num();
3720
3721 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3722 // in bytes - not the number of 'entries'. We need to convert
3723 // into a number of cards.
3724 return (buffer_size * buffer_num + extra_cards) / oopSize;
3725 }
3726
3727 size_t G1CollectedHeap::cards_scanned() {
3728 return g1_rem_set()->cardsScanned();
3729 }
3730
3731 void
3732 G1CollectedHeap::setup_surviving_young_words() {
3733 assert(_surviving_young_words == NULL, "pre-condition");
3734 uint array_length = g1_policy()->young_cset_region_length();
3735 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3736 if (_surviving_young_words == NULL) {
3737 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3738 "Not enough space for young surv words summary.");
3739 }
3740 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3741 #ifdef ASSERT
3742 for (uint i = 0; i < array_length; ++i) {
3743 assert( _surviving_young_words[i] == 0, "memset above" );
3744 }
3745 #endif // !ASSERT
3746 }
3747
3748 void
3749 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3750 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3751 uint array_length = g1_policy()->young_cset_region_length();
3752 for (uint i = 0; i < array_length; ++i) {
3753 _surviving_young_words[i] += surv_young_words[i];
3754 }
3755 }
3756
3757 void
3758 G1CollectedHeap::cleanup_surviving_young_words() {
3759 guarantee( _surviving_young_words != NULL, "pre-condition" );
3760 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3761 _surviving_young_words = NULL;
3762 }
3763
3764 #ifdef ASSERT
3765 class VerifyCSetClosure: public HeapRegionClosure {
3766 public:
3767 bool doHeapRegion(HeapRegion* hr) {
3768 // Here we check that the CSet region's RSet is ready for parallel
3769 // iteration. The fields that we'll verify are only manipulated
3770 // when the region is part of a CSet and is collected. Afterwards,
3771 // we reset these fields when we clear the region's RSet (when the
3772 // region is freed) so they are ready when the region is
3773 // re-allocated. The only exception to this is if there's an
3774 // evacuation failure and instead of freeing the region we leave
3775 // it in the heap. In that case, we reset these fields during
3776 // evacuation failure handling.
3777 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3778
3779 // Here's a good place to add any other checks we'd like to
3780 // perform on CSet regions.
3781 return false;
3782 }
3783 };
3784 #endif // ASSERT
3785
3786 #if TASKQUEUE_STATS
3787 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3788 st->print_raw_cr("GC Task Stats");
3789 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3790 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3791 }
3792
3793 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3794 print_taskqueue_stats_hdr(st);
3795
3796 TaskQueueStats totals;
3797 const int n = workers() != NULL ? workers()->total_workers() : 1;
3798 for (int i = 0; i < n; ++i) {
3799 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3800 totals += task_queue(i)->stats;
3801 }
3802 st->print_raw("tot "); totals.print(st); st->cr();
3803
3804 DEBUG_ONLY(totals.verify());
3805 }
3806
3807 void G1CollectedHeap::reset_taskqueue_stats() {
3808 const int n = workers() != NULL ? workers()->total_workers() : 1;
3809 for (int i = 0; i < n; ++i) {
3810 task_queue(i)->stats.reset();
3811 }
3812 }
3813 #endif // TASKQUEUE_STATS
3814
3815 void G1CollectedHeap::log_gc_header() {
3816 if (!G1Log::fine()) {
3817 return;
3818 }
3819
3820 gclog_or_tty->date_stamp(PrintGCDateStamps);
3821 gclog_or_tty->stamp(PrintGCTimeStamps);
3822
3823 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3824 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3825 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3826
3827 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3828 }
3829
3830 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3831 if (!G1Log::fine()) {
3832 return;
3833 }
3834
3835 if (G1Log::finer()) {
3836 if (evacuation_failed()) {
3837 gclog_or_tty->print(" (to-space exhausted)");
3838 }
3839 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3840 g1_policy()->phase_times()->note_gc_end();
3841 g1_policy()->phase_times()->print(pause_time_sec);
3842 g1_policy()->print_detailed_heap_transition();
3843 } else {
3844 if (evacuation_failed()) {
3845 gclog_or_tty->print("--");
3846 }
3847 g1_policy()->print_heap_transition();
3848 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3849 }
3850 gclog_or_tty->flush();
3851 }
3852
3853 bool
3854 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3855 assert_at_safepoint(true /* should_be_vm_thread */);
3856 guarantee(!is_gc_active(), "collection is not reentrant");
3857
3858 if (GC_locker::check_active_before_gc()) {
3859 return false;
3860 }
3861
3862 _gc_timer_stw->register_gc_start(os::elapsed_counter());
3863
3864 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3865
3866 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3867 ResourceMark rm;
3868
3869 print_heap_before_gc();
3870 trace_heap_before_gc(_gc_tracer_stw);
3871
3872 HRSPhaseSetter x(HRSPhaseEvacuation);
3873 verify_region_sets_optional();
3874 verify_dirty_young_regions();
3875
3876 // This call will decide whether this pause is an initial-mark
3877 // pause. If it is, during_initial_mark_pause() will return true
3878 // for the duration of this pause.
3879 g1_policy()->decide_on_conc_mark_initiation();
3880
3881 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3882 assert(!g1_policy()->during_initial_mark_pause() ||
3883 g1_policy()->gcs_are_young(), "sanity");
3884
3885 // We also do not allow mixed GCs during marking.
3886 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3887
3888 // Record whether this pause is an initial mark. When the current
3889 // thread has completed its logging output and it's safe to signal
3890 // the CM thread, the flag's value in the policy has been reset.
3891 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3892
3893 // Inner scope for scope based logging, timers, and stats collection
3894 {
3895 EvacuationInfo evacuation_info;
3896
3897 if (g1_policy()->during_initial_mark_pause()) {
3898 // We are about to start a marking cycle, so we increment the
3899 // full collection counter.
3900 increment_old_marking_cycles_started();
3901 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3902 }
3903
3904 _gc_tracer_stw->report_yc_type(yc_type());
3905
3906 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3907
3908 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3909 workers()->active_workers() : 1);
3910 double pause_start_sec = os::elapsedTime();
3911 g1_policy()->phase_times()->note_gc_start(active_workers);
3912 log_gc_header();
3913
3914 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3915 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3916
3917 // If the secondary_free_list is not empty, append it to the
3918 // free_list. No need to wait for the cleanup operation to finish;
3919 // the region allocation code will check the secondary_free_list
3920 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3921 // set, skip this step so that the region allocation code has to
3922 // get entries from the secondary_free_list.
3923 if (!G1StressConcRegionFreeing) {
3924 append_secondary_free_list_if_not_empty_with_lock();
3925 }
3926
3927 assert(check_young_list_well_formed(),
3928 "young list should be well formed");
3929
3930 // Don't dynamically change the number of GC threads this early. A value of
3931 // 0 is used to indicate serial work. When parallel work is done,
3932 // it will be set.
3933
3934 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3935 IsGCActiveMark x;
3936
3937 gc_prologue(false);
3938 increment_total_collections(false /* full gc */);
3939 increment_gc_time_stamp();
3940
3941 verify_before_gc();
3942
3943 COMPILER2_PRESENT(DerivedPointerTable::clear());
3944
3945 // Please see comment in g1CollectedHeap.hpp and
3946 // G1CollectedHeap::ref_processing_init() to see how
3947 // reference processing currently works in G1.
3948
3949 // Enable discovery in the STW reference processor
3950 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3951 true /*verify_no_refs*/);
3952
3953 {
3954 // We want to temporarily turn off discovery by the
3955 // CM ref processor, if necessary, and turn it back on
3956 // on again later if we do. Using a scoped
3957 // NoRefDiscovery object will do this.
3958 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3959
3960 // Forget the current alloc region (we might even choose it to be part
3961 // of the collection set!).
3962 release_mutator_alloc_region();
3963
3964 // We should call this after we retire the mutator alloc
3965 // region(s) so that all the ALLOC / RETIRE events are generated
3966 // before the start GC event.
3967 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3968
3969 // This timing is only used by the ergonomics to handle our pause target.
3970 // It is unclear why this should not include the full pause. We will
3971 // investigate this in CR 7178365.
3972 //
3973 // Preserving the old comment here if that helps the investigation:
3974 //
3975 // The elapsed time induced by the start time below deliberately elides
3976 // the possible verification above.
3977 double sample_start_time_sec = os::elapsedTime();
3978
3979 #if YOUNG_LIST_VERBOSE
3980 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3981 _young_list->print();
3982 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3983 #endif // YOUNG_LIST_VERBOSE
3984
3985 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3986
3987 double scan_wait_start = os::elapsedTime();
3988 // We have to wait until the CM threads finish scanning the
3989 // root regions as it's the only way to ensure that all the
3990 // objects on them have been correctly scanned before we start
3991 // moving them during the GC.
3992 bool waited = _cm->root_regions()->wait_until_scan_finished();
3993 double wait_time_ms = 0.0;
3994 if (waited) {
3995 double scan_wait_end = os::elapsedTime();
3996 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3997 }
3998 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3999
4000 #if YOUNG_LIST_VERBOSE
4001 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4002 _young_list->print();
4003 #endif // YOUNG_LIST_VERBOSE
4004
4005 if (g1_policy()->during_initial_mark_pause()) {
4006 concurrent_mark()->checkpointRootsInitialPre();
4007 }
4008
4009 #if YOUNG_LIST_VERBOSE
4010 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4011 _young_list->print();
4012 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4013 #endif // YOUNG_LIST_VERBOSE
4014
4015 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4016
4017 _cm->note_start_of_gc();
4018 // We should not verify the per-thread SATB buffers given that
4019 // we have not filtered them yet (we'll do so during the
4020 // GC). We also call this after finalize_cset() to
4021 // ensure that the CSet has been finalized.
4022 _cm->verify_no_cset_oops(true /* verify_stacks */,
4023 true /* verify_enqueued_buffers */,
4024 false /* verify_thread_buffers */,
4025 true /* verify_fingers */);
4026
4027 if (_hr_printer.is_active()) {
4028 HeapRegion* hr = g1_policy()->collection_set();
4029 while (hr != NULL) {
4030 G1HRPrinter::RegionType type;
4031 if (!hr->is_young()) {
4032 type = G1HRPrinter::Old;
4033 } else if (hr->is_survivor()) {
4034 type = G1HRPrinter::Survivor;
4035 } else {
4036 type = G1HRPrinter::Eden;
4037 }
4038 _hr_printer.cset(hr);
4039 hr = hr->next_in_collection_set();
4040 }
4041 }
4042
4043 #ifdef ASSERT
4044 VerifyCSetClosure cl;
4045 collection_set_iterate(&cl);
4046 #endif // ASSERT
4047
4048 setup_surviving_young_words();
4049
4050 // Initialize the GC alloc regions.
4051 init_gc_alloc_regions(evacuation_info);
4052
4053 // Actually do the work...
4054 evacuate_collection_set(evacuation_info);
4055
4056 // We do this to mainly verify the per-thread SATB buffers
4057 // (which have been filtered by now) since we didn't verify
4058 // them earlier. No point in re-checking the stacks / enqueued
4059 // buffers given that the CSet has not changed since last time
4060 // we checked.
4061 _cm->verify_no_cset_oops(false /* verify_stacks */,
4062 false /* verify_enqueued_buffers */,
4063 true /* verify_thread_buffers */,
4064 true /* verify_fingers */);
4065
4066 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4067 g1_policy()->clear_collection_set();
4068
4069 cleanup_surviving_young_words();
4070
4071 // Start a new incremental collection set for the next pause.
4072 g1_policy()->start_incremental_cset_building();
4073
4074 // Clear the _cset_fast_test bitmap in anticipation of adding
4075 // regions to the incremental collection set for the next
4076 // evacuation pause.
4077 clear_cset_fast_test();
4078
4079 _young_list->reset_sampled_info();
4080
4081 // Don't check the whole heap at this point as the
4082 // GC alloc regions from this pause have been tagged
4083 // as survivors and moved on to the survivor list.
4084 // Survivor regions will fail the !is_young() check.
4085 assert(check_young_list_empty(false /* check_heap */),
4086 "young list should be empty");
4087
4088 #if YOUNG_LIST_VERBOSE
4089 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4090 _young_list->print();
4091 #endif // YOUNG_LIST_VERBOSE
4092
4093 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4094 _young_list->first_survivor_region(),
4095 _young_list->last_survivor_region());
4096
4097 _young_list->reset_auxilary_lists();
4098
4099 if (evacuation_failed()) {
4100 _summary_bytes_used = recalculate_used();
4101 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4102 for (uint i = 0; i < n_queues; i++) {
4103 if (_evacuation_failed_info_array[i].has_failed()) {
4104 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4105 }
4106 }
4107 } else {
4108 // The "used" of the the collection set have already been subtracted
4109 // when they were freed. Add in the bytes evacuated.
4110 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4111 }
4112
4113 if (g1_policy()->during_initial_mark_pause()) {
4114 // We have to do this before we notify the CM threads that
4115 // they can start working to make sure that all the
4116 // appropriate initialization is done on the CM object.
4117 concurrent_mark()->checkpointRootsInitialPost();
4118 set_marking_started();
4119 // Note that we don't actually trigger the CM thread at
4120 // this point. We do that later when we're sure that
4121 // the current thread has completed its logging output.
4122 }
4123
4124 allocate_dummy_regions();
4125
4126 #if YOUNG_LIST_VERBOSE
4127 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4128 _young_list->print();
4129 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4130 #endif // YOUNG_LIST_VERBOSE
4131
4132 init_mutator_alloc_region();
4133
4134 {
4135 size_t expand_bytes = g1_policy()->expansion_amount();
4136 if (expand_bytes > 0) {
4137 size_t bytes_before = capacity();
4138 // No need for an ergo verbose message here,
4139 // expansion_amount() does this when it returns a value > 0.
4140 if (!expand(expand_bytes)) {
4141 // We failed to expand the heap so let's verify that
4142 // committed/uncommitted amount match the backing store
4143 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4144 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4145 }
4146 }
4147 }
4148
4149 // We redo the verification but now wrt to the new CSet which
4150 // has just got initialized after the previous CSet was freed.
4151 _cm->verify_no_cset_oops(true /* verify_stacks */,
4152 true /* verify_enqueued_buffers */,
4153 true /* verify_thread_buffers */,
4154 true /* verify_fingers */);
4155 _cm->note_end_of_gc();
4156
4157 // This timing is only used by the ergonomics to handle our pause target.
4158 // It is unclear why this should not include the full pause. We will
4159 // investigate this in CR 7178365.
4160 double sample_end_time_sec = os::elapsedTime();
4161 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4162 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4163
4164 MemoryService::track_memory_usage();
4165
4166 // In prepare_for_verify() below we'll need to scan the deferred
4167 // update buffers to bring the RSets up-to-date if
4168 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4169 // the update buffers we'll probably need to scan cards on the
4170 // regions we just allocated to (i.e., the GC alloc
4171 // regions). However, during the last GC we called
4172 // set_saved_mark() on all the GC alloc regions, so card
4173 // scanning might skip the [saved_mark_word()...top()] area of
4174 // those regions (i.e., the area we allocated objects into
4175 // during the last GC). But it shouldn't. Given that
4176 // saved_mark_word() is conditional on whether the GC time stamp
4177 // on the region is current or not, by incrementing the GC time
4178 // stamp here we invalidate all the GC time stamps on all the
4179 // regions and saved_mark_word() will simply return top() for
4180 // all the regions. This is a nicer way of ensuring this rather
4181 // than iterating over the regions and fixing them. In fact, the
4182 // GC time stamp increment here also ensures that
4183 // saved_mark_word() will return top() between pauses, i.e.,
4184 // during concurrent refinement. So we don't need the
4185 // is_gc_active() check to decided which top to use when
4186 // scanning cards (see CR 7039627).
4187 increment_gc_time_stamp();
4188
4189 verify_after_gc();
4190
4191 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4192 ref_processor_stw()->verify_no_references_recorded();
4193
4194 // CM reference discovery will be re-enabled if necessary.
4195 }
4196
4197 // We should do this after we potentially expand the heap so
4198 // that all the COMMIT events are generated before the end GC
4199 // event, and after we retire the GC alloc regions so that all
4200 // RETIRE events are generated before the end GC event.
4201 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4202
4203 if (mark_in_progress()) {
4204 concurrent_mark()->update_g1_committed();
4205 }
4206
4207 #ifdef TRACESPINNING
4208 ParallelTaskTerminator::print_termination_counts();
4209 #endif
4210
4211 gc_epilogue(false);
4212 }
4213
4214 // Print the remainder of the GC log output.
4215 log_gc_footer(os::elapsedTime() - pause_start_sec);
4216
4217 // It is not yet to safe to tell the concurrent mark to
4218 // start as we have some optional output below. We don't want the
4219 // output from the concurrent mark thread interfering with this
4220 // logging output either.
4221
4222 _hrs.verify_optional();
4223 verify_region_sets_optional();
4224
4225 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4226 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4227
4228 print_heap_after_gc();
4229 trace_heap_after_gc(_gc_tracer_stw);
4230
4231 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4232 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4233 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4234 // before any GC notifications are raised.
4235 g1mm()->update_sizes();
4236
4237 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4238 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4239 _gc_timer_stw->register_gc_end(os::elapsed_counter());
4240 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4241 }
4242 // It should now be safe to tell the concurrent mark thread to start
4243 // without its logging output interfering with the logging output
4244 // that came from the pause.
4245
4246 if (should_start_conc_mark) {
4247 // CAUTION: after the doConcurrentMark() call below,
4248 // the concurrent marking thread(s) could be running
4249 // concurrently with us. Make sure that anything after
4250 // this point does not assume that we are the only GC thread
4251 // running. Note: of course, the actual marking work will
4252 // not start until the safepoint itself is released in
4253 // ConcurrentGCThread::safepoint_desynchronize().
4254 doConcurrentMark();
4255 }
4256
4257 return true;
4258 }
4259
4260 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4261 {
4262 size_t gclab_word_size;
4263 switch (purpose) {
4264 case GCAllocForSurvived:
4265 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4266 break;
4267 case GCAllocForTenured:
4268 gclab_word_size = _old_plab_stats.desired_plab_sz();
4269 break;
4270 default:
4271 assert(false, "unknown GCAllocPurpose");
4272 gclab_word_size = _old_plab_stats.desired_plab_sz();
4273 break;
4274 }
4275
4276 // Prevent humongous PLAB sizes for two reasons:
4277 // * PLABs are allocated using a similar paths as oops, but should
4278 // never be in a humongous region
4279 // * Allowing humongous PLABs needlessly churns the region free lists
4280 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4281 }
4282
4283 void G1CollectedHeap::init_mutator_alloc_region() {
4284 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4285 _mutator_alloc_region.init();
4286 }
4287
4288 void G1CollectedHeap::release_mutator_alloc_region() {
4289 _mutator_alloc_region.release();
4290 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4291 }
4292
4293 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4294 assert_at_safepoint(true /* should_be_vm_thread */);
4295
4296 _survivor_gc_alloc_region.init();
4297 _old_gc_alloc_region.init();
4298 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4299 _retained_old_gc_alloc_region = NULL;
4300
4301 // We will discard the current GC alloc region if:
4302 // a) it's in the collection set (it can happen!),
4303 // b) it's already full (no point in using it),
4304 // c) it's empty (this means that it was emptied during
4305 // a cleanup and it should be on the free list now), or
4306 // d) it's humongous (this means that it was emptied
4307 // during a cleanup and was added to the free list, but
4308 // has been subsequently used to allocate a humongous
4309 // object that may be less than the region size).
4310 if (retained_region != NULL &&
4311 !retained_region->in_collection_set() &&
4312 !(retained_region->top() == retained_region->end()) &&
4313 !retained_region->is_empty() &&
4314 !retained_region->isHumongous()) {
4315 retained_region->set_saved_mark();
4316 // The retained region was added to the old region set when it was
4317 // retired. We have to remove it now, since we don't allow regions
4318 // we allocate to in the region sets. We'll re-add it later, when
4319 // it's retired again.
4320 _old_set.remove(retained_region);
4321 bool during_im = g1_policy()->during_initial_mark_pause();
4322 retained_region->note_start_of_copying(during_im);
4323 _old_gc_alloc_region.set(retained_region);
4324 _hr_printer.reuse(retained_region);
4325 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4326 }
4327 }
4328
4329 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4330 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4331 _old_gc_alloc_region.count());
4332 _survivor_gc_alloc_region.release();
4333 // If we have an old GC alloc region to release, we'll save it in
4334 // _retained_old_gc_alloc_region. If we don't
4335 // _retained_old_gc_alloc_region will become NULL. This is what we
4336 // want either way so no reason to check explicitly for either
4337 // condition.
4338 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4339
4340 if (ResizePLAB) {
4341 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4342 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4343 }
4344 }
4345
4346 void G1CollectedHeap::abandon_gc_alloc_regions() {
4347 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4348 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4349 _retained_old_gc_alloc_region = NULL;
4350 }
4351
4352 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4353 _drain_in_progress = false;
4354 set_evac_failure_closure(cl);
4355 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4356 }
4357
4358 void G1CollectedHeap::finalize_for_evac_failure() {
4359 assert(_evac_failure_scan_stack != NULL &&
4360 _evac_failure_scan_stack->length() == 0,
4361 "Postcondition");
4362 assert(!_drain_in_progress, "Postcondition");
4363 delete _evac_failure_scan_stack;
4364 _evac_failure_scan_stack = NULL;
4365 }
4366
4367 void G1CollectedHeap::remove_self_forwarding_pointers() {
4368 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4369
4370 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4371
4372 if (G1CollectedHeap::use_parallel_gc_threads()) {
4373 set_par_threads();
4374 workers()->run_task(&rsfp_task);
4375 set_par_threads(0);
4376 } else {
4377 rsfp_task.work(0);
4378 }
4379
4380 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4381
4382 // Reset the claim values in the regions in the collection set.
4383 reset_cset_heap_region_claim_values();
4384
4385 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4386
4387 // Now restore saved marks, if any.
4388 assert(_objs_with_preserved_marks.size() ==
4389 _preserved_marks_of_objs.size(), "Both or none.");
4390 while (!_objs_with_preserved_marks.is_empty()) {
4391 oop obj = _objs_with_preserved_marks.pop();
4392 markOop m = _preserved_marks_of_objs.pop();
4393 obj->set_mark(m);
4394 }
4395 _objs_with_preserved_marks.clear(true);
4396 _preserved_marks_of_objs.clear(true);
4397 }
4398
4399 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4400 _evac_failure_scan_stack->push(obj);
4401 }
4402
4403 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4404 assert(_evac_failure_scan_stack != NULL, "precondition");
4405
4406 while (_evac_failure_scan_stack->length() > 0) {
4407 oop obj = _evac_failure_scan_stack->pop();
4408 _evac_failure_closure->set_region(heap_region_containing(obj));
4409 obj->oop_iterate_backwards(_evac_failure_closure);
4410 }
4411 }
4412
4413 oop
4414 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4415 oop old) {
4416 assert(obj_in_cs(old),
4417 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4418 (HeapWord*) old));
4419 markOop m = old->mark();
4420 oop forward_ptr = old->forward_to_atomic(old);
4421 if (forward_ptr == NULL) {
4422 // Forward-to-self succeeded.
4423 assert(_par_scan_state != NULL, "par scan state");
4424 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4425 uint queue_num = _par_scan_state->queue_num();
4426
4427 _evacuation_failed = true;
4428 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4429 if (_evac_failure_closure != cl) {
4430 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4431 assert(!_drain_in_progress,
4432 "Should only be true while someone holds the lock.");
4433 // Set the global evac-failure closure to the current thread's.
4434 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4435 set_evac_failure_closure(cl);
4436 // Now do the common part.
4437 handle_evacuation_failure_common(old, m);
4438 // Reset to NULL.
4439 set_evac_failure_closure(NULL);
4440 } else {
4441 // The lock is already held, and this is recursive.
4442 assert(_drain_in_progress, "This should only be the recursive case.");
4443 handle_evacuation_failure_common(old, m);
4444 }
4445 return old;
4446 } else {
4447 // Forward-to-self failed. Either someone else managed to allocate
4448 // space for this object (old != forward_ptr) or they beat us in
4449 // self-forwarding it (old == forward_ptr).
4450 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4451 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4452 "should not be in the CSet",
4453 (HeapWord*) old, (HeapWord*) forward_ptr));
4454 return forward_ptr;
4455 }
4456 }
4457
4458 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4459 preserve_mark_if_necessary(old, m);
4460
4461 HeapRegion* r = heap_region_containing(old);
4462 if (!r->evacuation_failed()) {
4463 r->set_evacuation_failed(true);
4464 _hr_printer.evac_failure(r);
4465 }
4466
4467 push_on_evac_failure_scan_stack(old);
4468
4469 if (!_drain_in_progress) {
4470 // prevent recursion in copy_to_survivor_space()
4471 _drain_in_progress = true;
4472 drain_evac_failure_scan_stack();
4473 _drain_in_progress = false;
4474 }
4475 }
4476
4477 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4478 assert(evacuation_failed(), "Oversaving!");
4479 // We want to call the "for_promotion_failure" version only in the
4480 // case of a promotion failure.
4481 if (m->must_be_preserved_for_promotion_failure(obj)) {
4482 _objs_with_preserved_marks.push(obj);
4483 _preserved_marks_of_objs.push(m);
4484 }
4485 }
4486
4487 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4488 size_t word_size) {
4489 if (purpose == GCAllocForSurvived) {
4490 HeapWord* result = survivor_attempt_allocation(word_size);
4491 if (result != NULL) {
4492 return result;
4493 } else {
4494 // Let's try to allocate in the old gen in case we can fit the
4495 // object there.
4496 return old_attempt_allocation(word_size);
4497 }
4498 } else {
4499 assert(purpose == GCAllocForTenured, "sanity");
4500 HeapWord* result = old_attempt_allocation(word_size);
4501 if (result != NULL) {
4502 return result;
4503 } else {
4504 // Let's try to allocate in the survivors in case we can fit the
4505 // object there.
4506 return survivor_attempt_allocation(word_size);
4507 }
4508 }
4509
4510 ShouldNotReachHere();
4511 // Trying to keep some compilers happy.
4512 return NULL;
4513 }
4514
4515 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4516 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4517
4518 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4519 : _g1h(g1h),
4520 _refs(g1h->task_queue(queue_num)),
4521 _dcq(&g1h->dirty_card_queue_set()),
4522 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4523 _g1_rem(g1h->g1_rem_set()),
4524 _hash_seed(17), _queue_num(queue_num),
4525 _term_attempts(0),
4526 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4527 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4528 _age_table(false),
4529 _strong_roots_time(0), _term_time(0),
4530 _alloc_buffer_waste(0), _undo_waste(0) {
4531 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4532 // we "sacrifice" entry 0 to keep track of surviving bytes for
4533 // non-young regions (where the age is -1)
4534 // We also add a few elements at the beginning and at the end in
4535 // an attempt to eliminate cache contention
4536 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4537 uint array_length = PADDING_ELEM_NUM +
4538 real_length +
4539 PADDING_ELEM_NUM;
4540 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4541 if (_surviving_young_words_base == NULL)
4542 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4543 "Not enough space for young surv histo.");
4544 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4545 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4546
4547 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4548 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4549
4550 _start = os::elapsedTime();
4551 }
4552
4553 void
4554 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4555 {
4556 st->print_raw_cr("GC Termination Stats");
4557 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4558 " ------waste (KiB)------");
4559 st->print_raw_cr("thr ms ms % ms % attempts"
4560 " total alloc undo");
4561 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4562 " ------- ------- -------");
4563 }
4564
4565 void
4566 G1ParScanThreadState::print_termination_stats(int i,
4567 outputStream* const st) const
4568 {
4569 const double elapsed_ms = elapsed_time() * 1000.0;
4570 const double s_roots_ms = strong_roots_time() * 1000.0;
4571 const double term_ms = term_time() * 1000.0;
4572 st->print_cr("%3d %9.2f %9.2f %6.2f "
4573 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4574 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4575 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4576 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4577 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4578 alloc_buffer_waste() * HeapWordSize / K,
4579 undo_waste() * HeapWordSize / K);
4580 }
4581
4582 #ifdef ASSERT
4583 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4584 assert(ref != NULL, "invariant");
4585 assert(UseCompressedOops, "sanity");
4586 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4587 oop p = oopDesc::load_decode_heap_oop(ref);
4588 assert(_g1h->is_in_g1_reserved(p),
4589 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4590 return true;
4591 }
4592
4593 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4594 assert(ref != NULL, "invariant");
4595 if (has_partial_array_mask(ref)) {
4596 // Must be in the collection set--it's already been copied.
4597 oop p = clear_partial_array_mask(ref);
4598 assert(_g1h->obj_in_cs(p),
4599 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4600 } else {
4601 oop p = oopDesc::load_decode_heap_oop(ref);
4602 assert(_g1h->is_in_g1_reserved(p),
4603 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4604 }
4605 return true;
4606 }
4607
4608 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4609 if (ref.is_narrow()) {
4610 return verify_ref((narrowOop*) ref);
4611 } else {
4612 return verify_ref((oop*) ref);
4613 }
4614 }
4615 #endif // ASSERT
4616
4617 void G1ParScanThreadState::trim_queue() {
4618 assert(_evac_cl != NULL, "not set");
4619 assert(_evac_failure_cl != NULL, "not set");
4620 assert(_partial_scan_cl != NULL, "not set");
4621
4622 StarTask ref;
4623 do {
4624 // Drain the overflow stack first, so other threads can steal.
4625 while (refs()->pop_overflow(ref)) {
4626 deal_with_reference(ref);
4627 }
4628
4629 while (refs()->pop_local(ref)) {
4630 deal_with_reference(ref);
4631 }
4632 } while (!refs()->is_empty());
4633 }
4634
4635 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4636 G1ParScanThreadState* par_scan_state) :
4637 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4638 _par_scan_state(par_scan_state),
4639 _worker_id(par_scan_state->queue_num()),
4640 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4641 _mark_in_progress(_g1->mark_in_progress()) { }
4642
4643 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4644 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4645 #ifdef ASSERT
4646 HeapRegion* hr = _g1->heap_region_containing(obj);
4647 assert(hr != NULL, "sanity");
4648 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4649 #endif // ASSERT
4650
4651 // We know that the object is not moving so it's safe to read its size.
4652 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4653 }
4654
4655 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4656 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4657 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4658 #ifdef ASSERT
4659 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4660 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4661 assert(from_obj != to_obj, "should not be self-forwarded");
4662
4663 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4664 assert(from_hr != NULL, "sanity");
4665 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4666
4667 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4668 assert(to_hr != NULL, "sanity");
4669 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4670 #endif // ASSERT
4671
4672 // The object might be in the process of being copied by another
4673 // worker so we cannot trust that its to-space image is
4674 // well-formed. So we have to read its size from its from-space
4675 // image which we know should not be changing.
4676 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4677 }
4678
4679 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4680 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4681 ::copy_to_survivor_space(oop old) {
4682 size_t word_sz = old->size();
4683 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4684 // +1 to make the -1 indexes valid...
4685 int young_index = from_region->young_index_in_cset()+1;
4686 assert( (from_region->is_young() && young_index > 0) ||
4687 (!from_region->is_young() && young_index == 0), "invariant" );
4688 G1CollectorPolicy* g1p = _g1->g1_policy();
4689 markOop m = old->mark();
4690 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4691 : m->age();
4692 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4693 word_sz);
4694 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4695 #ifndef PRODUCT
4696 // Should this evacuation fail?
4697 if (_g1->evacuation_should_fail()) {
4698 if (obj_ptr != NULL) {
4699 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4700 obj_ptr = NULL;
4701 }
4702 }
4703 #endif // !PRODUCT
4704
4705 if (obj_ptr == NULL) {
4706 // This will either forward-to-self, or detect that someone else has
4707 // installed a forwarding pointer.
4708 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4709 }
4710
4711 oop obj = oop(obj_ptr);
4712
4713 // We're going to allocate linearly, so might as well prefetch ahead.
4714 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4715
4716 oop forward_ptr = old->forward_to_atomic(obj);
4717 if (forward_ptr == NULL) {
4718 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4719 if (g1p->track_object_age(alloc_purpose)) {
4720 // We could simply do obj->incr_age(). However, this causes a
4721 // performance issue. obj->incr_age() will first check whether
4722 // the object has a displaced mark by checking its mark word;
4723 // getting the mark word from the new location of the object
4724 // stalls. So, given that we already have the mark word and we
4725 // are about to install it anyway, it's better to increase the
4726 // age on the mark word, when the object does not have a
4727 // displaced mark word. We're not expecting many objects to have
4728 // a displaced marked word, so that case is not optimized
4729 // further (it could be...) and we simply call obj->incr_age().
4730
4731 if (m->has_displaced_mark_helper()) {
4732 // in this case, we have to install the mark word first,
4733 // otherwise obj looks to be forwarded (the old mark word,
4734 // which contains the forward pointer, was copied)
4735 obj->set_mark(m);
4736 obj->incr_age();
4737 } else {
4738 m = m->incr_age();
4739 obj->set_mark(m);
4740 }
4741 _par_scan_state->age_table()->add(obj, word_sz);
4742 } else {
4743 obj->set_mark(m);
4744 }
4745
4746 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4747 surv_young_words[young_index] += word_sz;
4748
4749 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4750 // We keep track of the next start index in the length field of
4751 // the to-space object. The actual length can be found in the
4752 // length field of the from-space object.
4753 arrayOop(obj)->set_length(0);
4754 oop* old_p = set_partial_array_mask(old);
4755 _par_scan_state->push_on_queue(old_p);
4756 } else {
4757 // No point in using the slower heap_region_containing() method,
4758 // given that we know obj is in the heap.
4759 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4760 obj->oop_iterate_backwards(&_scanner);
4761 }
4762 } else {
4763 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4764 obj = forward_ptr;
4765 }
4766 return obj;
4767 }
4768
4769 template <class T>
4770 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4771 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4772 _scanned_klass->record_modified_oops();
4773 }
4774 }
4775
4776 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4777 template <class T>
4778 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4779 ::do_oop_work(T* p) {
4780 oop obj = oopDesc::load_decode_heap_oop(p);
4781 assert(barrier != G1BarrierRS || obj != NULL,
4782 "Precondition: G1BarrierRS implies obj is non-NULL");
4783
4784 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4785
4786 // here the null check is implicit in the cset_fast_test() test
4787 if (_g1->in_cset_fast_test(obj)) {
4788 oop forwardee;
4789 if (obj->is_forwarded()) {
4790 forwardee = obj->forwardee();
4791 } else {
4792 forwardee = copy_to_survivor_space(obj);
4793 }
4794 assert(forwardee != NULL, "forwardee should not be NULL");
4795 oopDesc::encode_store_heap_oop(p, forwardee);
4796 if (do_mark_object && forwardee != obj) {
4797 // If the object is self-forwarded we don't need to explicitly
4798 // mark it, the evacuation failure protocol will do so.
4799 mark_forwarded_object(obj, forwardee);
4800 }
4801
4802 // When scanning the RS, we only care about objs in CS.
4803 if (barrier == G1BarrierRS) {
4804 _par_scan_state->update_rs(_from, p, _worker_id);
4805 } else if (barrier == G1BarrierKlass) {
4806 do_klass_barrier(p, forwardee);
4807 }
4808 } else {
4809 // The object is not in collection set. If we're a root scanning
4810 // closure during an initial mark pause (i.e. do_mark_object will
4811 // be true) then attempt to mark the object.
4812 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4813 mark_object(obj);
4814 }
4815 }
4816
4817 if (barrier == G1BarrierEvac && obj != NULL) {
4818 _par_scan_state->update_rs(_from, p, _worker_id);
4819 }
4820
4821 if (do_gen_barrier && obj != NULL) {
4822 par_do_barrier(p);
4823 }
4824 }
4825
4826 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4827 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4828
4829 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4830 assert(has_partial_array_mask(p), "invariant");
4831 oop from_obj = clear_partial_array_mask(p);
4832
4833 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4834 assert(from_obj->is_objArray(), "must be obj array");
4835 objArrayOop from_obj_array = objArrayOop(from_obj);
4836 // The from-space object contains the real length.
4837 int length = from_obj_array->length();
4838
4839 assert(from_obj->is_forwarded(), "must be forwarded");
4840 oop to_obj = from_obj->forwardee();
4841 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4842 objArrayOop to_obj_array = objArrayOop(to_obj);
4843 // We keep track of the next start index in the length field of the
4844 // to-space object.
4845 int next_index = to_obj_array->length();
4846 assert(0 <= next_index && next_index < length,
4847 err_msg("invariant, next index: %d, length: %d", next_index, length));
4848
4849 int start = next_index;
4850 int end = length;
4851 int remainder = end - start;
4852 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4853 if (remainder > 2 * ParGCArrayScanChunk) {
4854 end = start + ParGCArrayScanChunk;
4855 to_obj_array->set_length(end);
4856 // Push the remainder before we process the range in case another
4857 // worker has run out of things to do and can steal it.
4858 oop* from_obj_p = set_partial_array_mask(from_obj);
4859 _par_scan_state->push_on_queue(from_obj_p);
4860 } else {
4861 assert(length == end, "sanity");
4862 // We'll process the final range for this object. Restore the length
4863 // so that the heap remains parsable in case of evacuation failure.
4864 to_obj_array->set_length(end);
4865 }
4866 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4867 // Process indexes [start,end). It will also process the header
4868 // along with the first chunk (i.e., the chunk with start == 0).
4869 // Note that at this point the length field of to_obj_array is not
4870 // correct given that we are using it to keep track of the next
4871 // start index. oop_iterate_range() (thankfully!) ignores the length
4872 // field and only relies on the start / end parameters. It does
4873 // however return the size of the object which will be incorrect. So
4874 // we have to ignore it even if we wanted to use it.
4875 to_obj_array->oop_iterate_range(&_scanner, start, end);
4876 }
4877
4878 class G1ParEvacuateFollowersClosure : public VoidClosure {
4879 protected:
4880 G1CollectedHeap* _g1h;
4881 G1ParScanThreadState* _par_scan_state;
4882 RefToScanQueueSet* _queues;
4883 ParallelTaskTerminator* _terminator;
4884
4885 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4886 RefToScanQueueSet* queues() { return _queues; }
4887 ParallelTaskTerminator* terminator() { return _terminator; }
4888
4889 public:
4890 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4891 G1ParScanThreadState* par_scan_state,
4892 RefToScanQueueSet* queues,
4893 ParallelTaskTerminator* terminator)
4894 : _g1h(g1h), _par_scan_state(par_scan_state),
4895 _queues(queues), _terminator(terminator) {}
4896
4897 void do_void();
4898
4899 private:
4900 inline bool offer_termination();
4901 };
4902
4903 bool G1ParEvacuateFollowersClosure::offer_termination() {
4904 G1ParScanThreadState* const pss = par_scan_state();
4905 pss->start_term_time();
4906 const bool res = terminator()->offer_termination();
4907 pss->end_term_time();
4908 return res;
4909 }
4910
4911 void G1ParEvacuateFollowersClosure::do_void() {
4912 StarTask stolen_task;
4913 G1ParScanThreadState* const pss = par_scan_state();
4914 pss->trim_queue();
4915
4916 do {
4917 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4918 assert(pss->verify_task(stolen_task), "sanity");
4919 if (stolen_task.is_narrow()) {
4920 pss->deal_with_reference((narrowOop*) stolen_task);
4921 } else {
4922 pss->deal_with_reference((oop*) stolen_task);
4923 }
4924
4925 // We've just processed a reference and we might have made
4926 // available new entries on the queues. So we have to make sure
4927 // we drain the queues as necessary.
4928 pss->trim_queue();
4929 }
4930 } while (!offer_termination());
4931
4932 pss->retire_alloc_buffers();
4933 }
4934
4935 class G1KlassScanClosure : public KlassClosure {
4936 G1ParCopyHelper* _closure;
4937 bool _process_only_dirty;
4938 int _count;
4939 public:
4940 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4941 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4942 void do_klass(Klass* klass) {
4943 // If the klass has not been dirtied we know that there's
4944 // no references into the young gen and we can skip it.
4945 if (!_process_only_dirty || klass->has_modified_oops()) {
4946 // Clean the klass since we're going to scavenge all the metadata.
4947 klass->clear_modified_oops();
4948
4949 // Tell the closure that this klass is the Klass to scavenge
4950 // and is the one to dirty if oops are left pointing into the young gen.
4951 _closure->set_scanned_klass(klass);
4952
4953 klass->oops_do(_closure);
4954
4955 _closure->set_scanned_klass(NULL);
4956 }
4957 _count++;
4958 }
4959 };
4960
4961 class G1ParTask : public AbstractGangTask {
4962 protected:
4963 G1CollectedHeap* _g1h;
4964 RefToScanQueueSet *_queues;
4965 ParallelTaskTerminator _terminator;
4966 uint _n_workers;
4967
4968 Mutex _stats_lock;
4969 Mutex* stats_lock() { return &_stats_lock; }
4970
4971 size_t getNCards() {
4972 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4973 / G1BlockOffsetSharedArray::N_bytes;
4974 }
4975
4976 public:
4977 G1ParTask(G1CollectedHeap* g1h,
4978 RefToScanQueueSet *task_queues)
4979 : AbstractGangTask("G1 collection"),
4980 _g1h(g1h),
4981 _queues(task_queues),
4982 _terminator(0, _queues),
4983 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4984 {}
4985
4986 RefToScanQueueSet* queues() { return _queues; }
4987
4988 RefToScanQueue *work_queue(int i) {
4989 return queues()->queue(i);
4990 }
4991
4992 ParallelTaskTerminator* terminator() { return &_terminator; }
4993
4994 virtual void set_for_termination(int active_workers) {
4995 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4996 // in the young space (_par_seq_tasks) in the G1 heap
4997 // for SequentialSubTasksDone.
4998 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4999 // both of which need setting by set_n_termination().
5000 _g1h->SharedHeap::set_n_termination(active_workers);
5001 _g1h->set_n_termination(active_workers);
5002 terminator()->reset_for_reuse(active_workers);
5003 _n_workers = active_workers;
5004 }
5005
5006 void work(uint worker_id) {
5007 if (worker_id >= _n_workers) return; // no work needed this round
5008
5009 double start_time_ms = os::elapsedTime() * 1000.0;
5010 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5011
5012 {
5013 ResourceMark rm;
5014 HandleMark hm;
5015
5016 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5017
5018 G1ParScanThreadState pss(_g1h, worker_id);
5019 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5020 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5021 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5022
5023 pss.set_evac_closure(&scan_evac_cl);
5024 pss.set_evac_failure_closure(&evac_failure_cl);
5025 pss.set_partial_scan_closure(&partial_scan_cl);
5026
5027 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5028 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5029
5030 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5031 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5032
5033 bool only_young = _g1h->g1_policy()->gcs_are_young();
5034 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5035 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5036
5037 OopClosure* scan_root_cl = &only_scan_root_cl;
5038 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5039
5040 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5041 // We also need to mark copied objects.
5042 scan_root_cl = &scan_mark_root_cl;
5043 scan_klasses_cl = &scan_mark_klasses_cl_s;
5044 }
5045
5046 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5047
5048 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
5049
5050 pss.start_strong_roots();
5051 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5052 SharedHeap::ScanningOption(so),
5053 scan_root_cl,
5054 &push_heap_rs_cl,
5055 scan_klasses_cl,
5056 worker_id);
5057 pss.end_strong_roots();
5058
5059 {
5060 double start = os::elapsedTime();
5061 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5062 evac.do_void();
5063 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5064 double term_ms = pss.term_time()*1000.0;
5065 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5066 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5067 }
5068 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5069 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5070
5071 if (ParallelGCVerbose) {
5072 MutexLocker x(stats_lock());
5073 pss.print_termination_stats(worker_id);
5074 }
5075
5076 assert(pss.refs()->is_empty(), "should be empty");
5077
5078 // Close the inner scope so that the ResourceMark and HandleMark
5079 // destructors are executed here and are included as part of the
5080 // "GC Worker Time".
5081 }
5082
5083 double end_time_ms = os::elapsedTime() * 1000.0;
5084 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5085 }
5086 };
5087
5088 // *** Common G1 Evacuation Stuff
5089
5090 // Closures that support the filtering of CodeBlobs scanned during
5091 // external root scanning.
5092
5093 // Closure applied to reference fields in code blobs (specifically nmethods)
5094 // to determine whether an nmethod contains references that point into
5095 // the collection set. Used as a predicate when walking code roots so
5096 // that only nmethods that point into the collection set are added to the
5097 // 'marked' list.
5098
5099 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
5100
5101 class G1PointsIntoCSOopClosure : public OopClosure {
5102 G1CollectedHeap* _g1;
5103 bool _points_into_cs;
5104 public:
5105 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
5106 _g1(g1), _points_into_cs(false) { }
5107
5108 bool points_into_cs() const { return _points_into_cs; }
5109
5110 template <class T>
5111 void do_oop_nv(T* p) {
5112 if (!_points_into_cs) {
5113 T heap_oop = oopDesc::load_heap_oop(p);
5114 if (!oopDesc::is_null(heap_oop) &&
5115 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
5116 _points_into_cs = true;
5117 }
5118 }
5119 }
5120
5121 virtual void do_oop(oop* p) { do_oop_nv(p); }
5122 virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
5123 };
5124
5125 G1CollectedHeap* _g1;
5126
5127 public:
5128 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
5129 CodeBlobToOopClosure(cl, true), _g1(g1) { }
5130
5131 virtual void do_code_blob(CodeBlob* cb) {
5132 nmethod* nm = cb->as_nmethod_or_null();
5133 if (nm != NULL && !(nm->test_oops_do_mark())) {
5134 G1PointsIntoCSOopClosure predicate_cl(_g1);
5135 nm->oops_do(&predicate_cl);
5136
5137 if (predicate_cl.points_into_cs()) {
5138 // At least one of the reference fields or the oop relocations
5139 // in the nmethod points into the collection set. We have to
5140 // 'mark' this nmethod.
5141 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
5142 // or MarkingCodeBlobClosure::do_code_blob() change.
5143 if (!nm->test_set_oops_do_mark()) {
5144 do_newly_marked_nmethod(nm);
5145 }
5146 }
5147 }
5148 }
5149 };
5150
5151 // This method is run in a GC worker.
5152
5153 void
5154 G1CollectedHeap::
5155 g1_process_strong_roots(bool is_scavenging,
5156 ScanningOption so,
5157 OopClosure* scan_non_heap_roots,
5158 OopsInHeapRegionClosure* scan_rs,
5159 G1KlassScanClosure* scan_klasses,
5160 int worker_i) {
5161
5162 // First scan the strong roots
5163 double ext_roots_start = os::elapsedTime();
5164 double closure_app_time_sec = 0.0;
5165
5166 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5167
5168 // Walk the code cache w/o buffering, because StarTask cannot handle
5169 // unaligned oop locations.
5170 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5171
5172 process_strong_roots(false, // no scoping; this is parallel code
5173 is_scavenging, so,
5174 &buf_scan_non_heap_roots,
5175 &eager_scan_code_roots,
5176 scan_klasses
5177 );
5178
5179 // Now the CM ref_processor roots.
5180 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5181 // We need to treat the discovered reference lists of the
5182 // concurrent mark ref processor as roots and keep entries
5183 // (which are added by the marking threads) on them live
5184 // until they can be processed at the end of marking.
5185 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5186 }
5187
5188 // Finish up any enqueued closure apps (attributed as object copy time).
5189 buf_scan_non_heap_roots.done();
5190
5191 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5192
5193 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5194
5195 double ext_root_time_ms =
5196 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5197
5198 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5199
5200 // During conc marking we have to filter the per-thread SATB buffers
5201 // to make sure we remove any oops into the CSet (which will show up
5202 // as implicitly live).
5203 double satb_filtering_ms = 0.0;
5204 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5205 if (mark_in_progress()) {
5206 double satb_filter_start = os::elapsedTime();
5207
5208 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5209
5210 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5211 }
5212 }
5213 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5214
5215 // Now scan the complement of the collection set.
5216 if (scan_rs != NULL) {
5217 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5218 }
5219 _process_strong_tasks->all_tasks_completed();
5220 }
5221
5222 void
5223 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5224 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5225 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5226 }
5227
5228 // Weak Reference Processing support
5229
5230 // An always "is_alive" closure that is used to preserve referents.
5231 // If the object is non-null then it's alive. Used in the preservation
5232 // of referent objects that are pointed to by reference objects
5233 // discovered by the CM ref processor.
5234 class G1AlwaysAliveClosure: public BoolObjectClosure {
5235 G1CollectedHeap* _g1;
5236 public:
5237 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5238 bool do_object_b(oop p) {
5239 if (p != NULL) {
5240 return true;
5241 }
5242 return false;
5243 }
5244 };
5245
5246 bool G1STWIsAliveClosure::do_object_b(oop p) {
5247 // An object is reachable if it is outside the collection set,
5248 // or is inside and copied.
5249 return !_g1->obj_in_cs(p) || p->is_forwarded();
5250 }
5251
5252 // Non Copying Keep Alive closure
5253 class G1KeepAliveClosure: public OopClosure {
5254 G1CollectedHeap* _g1;
5255 public:
5256 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5257 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5258 void do_oop( oop* p) {
5259 oop obj = *p;
5260
5261 if (_g1->obj_in_cs(obj)) {
5262 assert( obj->is_forwarded(), "invariant" );
5263 *p = obj->forwardee();
5264 }
5265 }
5266 };
5267
5268 // Copying Keep Alive closure - can be called from both
5269 // serial and parallel code as long as different worker
5270 // threads utilize different G1ParScanThreadState instances
5271 // and different queues.
5272
5273 class G1CopyingKeepAliveClosure: public OopClosure {
5274 G1CollectedHeap* _g1h;
5275 OopClosure* _copy_non_heap_obj_cl;
5276 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5277 G1ParScanThreadState* _par_scan_state;
5278
5279 public:
5280 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5281 OopClosure* non_heap_obj_cl,
5282 OopsInHeapRegionClosure* metadata_obj_cl,
5283 G1ParScanThreadState* pss):
5284 _g1h(g1h),
5285 _copy_non_heap_obj_cl(non_heap_obj_cl),
5286 _copy_metadata_obj_cl(metadata_obj_cl),
5287 _par_scan_state(pss)
5288 {}
5289
5290 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5291 virtual void do_oop( oop* p) { do_oop_work(p); }
5292
5293 template <class T> void do_oop_work(T* p) {
5294 oop obj = oopDesc::load_decode_heap_oop(p);
5295
5296 if (_g1h->obj_in_cs(obj)) {
5297 // If the referent object has been forwarded (either copied
5298 // to a new location or to itself in the event of an
5299 // evacuation failure) then we need to update the reference
5300 // field and, if both reference and referent are in the G1
5301 // heap, update the RSet for the referent.
5302 //
5303 // If the referent has not been forwarded then we have to keep
5304 // it alive by policy. Therefore we have copy the referent.
5305 //
5306 // If the reference field is in the G1 heap then we can push
5307 // on the PSS queue. When the queue is drained (after each
5308 // phase of reference processing) the object and it's followers
5309 // will be copied, the reference field set to point to the
5310 // new location, and the RSet updated. Otherwise we need to
5311 // use the the non-heap or metadata closures directly to copy
5312 // the referent object and update the pointer, while avoiding
5313 // updating the RSet.
5314
5315 if (_g1h->is_in_g1_reserved(p)) {
5316 _par_scan_state->push_on_queue(p);
5317 } else {
5318 assert(!ClassLoaderDataGraph::contains((address)p),
5319 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5320 PTR_FORMAT, p));
5321 _copy_non_heap_obj_cl->do_oop(p);
5322 }
5323 }
5324 }
5325 };
5326
5327 // Serial drain queue closure. Called as the 'complete_gc'
5328 // closure for each discovered list in some of the
5329 // reference processing phases.
5330
5331 class G1STWDrainQueueClosure: public VoidClosure {
5332 protected:
5333 G1CollectedHeap* _g1h;
5334 G1ParScanThreadState* _par_scan_state;
5335
5336 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5337
5338 public:
5339 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5340 _g1h(g1h),
5341 _par_scan_state(pss)
5342 { }
5343
5344 void do_void() {
5345 G1ParScanThreadState* const pss = par_scan_state();
5346 pss->trim_queue();
5347 }
5348 };
5349
5350 // Parallel Reference Processing closures
5351
5352 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5353 // processing during G1 evacuation pauses.
5354
5355 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5356 private:
5357 G1CollectedHeap* _g1h;
5358 RefToScanQueueSet* _queues;
5359 FlexibleWorkGang* _workers;
5360 int _active_workers;
5361
5362 public:
5363 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5364 FlexibleWorkGang* workers,
5365 RefToScanQueueSet *task_queues,
5366 int n_workers) :
5367 _g1h(g1h),
5368 _queues(task_queues),
5369 _workers(workers),
5370 _active_workers(n_workers)
5371 {
5372 assert(n_workers > 0, "shouldn't call this otherwise");
5373 }
5374
5375 // Executes the given task using concurrent marking worker threads.
5376 virtual void execute(ProcessTask& task);
5377 virtual void execute(EnqueueTask& task);
5378 };
5379
5380 // Gang task for possibly parallel reference processing
5381
5382 class G1STWRefProcTaskProxy: public AbstractGangTask {
5383 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5384 ProcessTask& _proc_task;
5385 G1CollectedHeap* _g1h;
5386 RefToScanQueueSet *_task_queues;
5387 ParallelTaskTerminator* _terminator;
5388
5389 public:
5390 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5391 G1CollectedHeap* g1h,
5392 RefToScanQueueSet *task_queues,
5393 ParallelTaskTerminator* terminator) :
5394 AbstractGangTask("Process reference objects in parallel"),
5395 _proc_task(proc_task),
5396 _g1h(g1h),
5397 _task_queues(task_queues),
5398 _terminator(terminator)
5399 {}
5400
5401 virtual void work(uint worker_id) {
5402 // The reference processing task executed by a single worker.
5403 ResourceMark rm;
5404 HandleMark hm;
5405
5406 G1STWIsAliveClosure is_alive(_g1h);
5407
5408 G1ParScanThreadState pss(_g1h, worker_id);
5409
5410 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5411 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5412 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5413
5414 pss.set_evac_closure(&scan_evac_cl);
5415 pss.set_evac_failure_closure(&evac_failure_cl);
5416 pss.set_partial_scan_closure(&partial_scan_cl);
5417
5418 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5419 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5420
5421 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5422 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5423
5424 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5425 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5426
5427 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5428 // We also need to mark copied objects.
5429 copy_non_heap_cl = ©_mark_non_heap_cl;
5430 copy_metadata_cl = ©_mark_metadata_cl;
5431 }
5432
5433 // Keep alive closure.
5434 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5435
5436 // Complete GC closure
5437 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5438
5439 // Call the reference processing task's work routine.
5440 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5441
5442 // Note we cannot assert that the refs array is empty here as not all
5443 // of the processing tasks (specifically phase2 - pp2_work) execute
5444 // the complete_gc closure (which ordinarily would drain the queue) so
5445 // the queue may not be empty.
5446 }
5447 };
5448
5449 // Driver routine for parallel reference processing.
5450 // Creates an instance of the ref processing gang
5451 // task and has the worker threads execute it.
5452 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5453 assert(_workers != NULL, "Need parallel worker threads.");
5454
5455 ParallelTaskTerminator terminator(_active_workers, _queues);
5456 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5457
5458 _g1h->set_par_threads(_active_workers);
5459 _workers->run_task(&proc_task_proxy);
5460 _g1h->set_par_threads(0);
5461 }
5462
5463 // Gang task for parallel reference enqueueing.
5464
5465 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5466 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5467 EnqueueTask& _enq_task;
5468
5469 public:
5470 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5471 AbstractGangTask("Enqueue reference objects in parallel"),
5472 _enq_task(enq_task)
5473 { }
5474
5475 virtual void work(uint worker_id) {
5476 _enq_task.work(worker_id);
5477 }
5478 };
5479
5480 // Driver routine for parallel reference enqueueing.
5481 // Creates an instance of the ref enqueueing gang
5482 // task and has the worker threads execute it.
5483
5484 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5485 assert(_workers != NULL, "Need parallel worker threads.");
5486
5487 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5488
5489 _g1h->set_par_threads(_active_workers);
5490 _workers->run_task(&enq_task_proxy);
5491 _g1h->set_par_threads(0);
5492 }
5493
5494 // End of weak reference support closures
5495
5496 // Abstract task used to preserve (i.e. copy) any referent objects
5497 // that are in the collection set and are pointed to by reference
5498 // objects discovered by the CM ref processor.
5499
5500 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5501 protected:
5502 G1CollectedHeap* _g1h;
5503 RefToScanQueueSet *_queues;
5504 ParallelTaskTerminator _terminator;
5505 uint _n_workers;
5506
5507 public:
5508 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5509 AbstractGangTask("ParPreserveCMReferents"),
5510 _g1h(g1h),
5511 _queues(task_queues),
5512 _terminator(workers, _queues),
5513 _n_workers(workers)
5514 { }
5515
5516 void work(uint worker_id) {
5517 ResourceMark rm;
5518 HandleMark hm;
5519
5520 G1ParScanThreadState pss(_g1h, worker_id);
5521 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5522 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5523 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5524
5525 pss.set_evac_closure(&scan_evac_cl);
5526 pss.set_evac_failure_closure(&evac_failure_cl);
5527 pss.set_partial_scan_closure(&partial_scan_cl);
5528
5529 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5530
5531
5532 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5533 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5534
5535 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5536 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5537
5538 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5539 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5540
5541 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5542 // We also need to mark copied objects.
5543 copy_non_heap_cl = ©_mark_non_heap_cl;
5544 copy_metadata_cl = ©_mark_metadata_cl;
5545 }
5546
5547 // Is alive closure
5548 G1AlwaysAliveClosure always_alive(_g1h);
5549
5550 // Copying keep alive closure. Applied to referent objects that need
5551 // to be copied.
5552 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5553
5554 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5555
5556 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5557 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5558
5559 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5560 // So this must be true - but assert just in case someone decides to
5561 // change the worker ids.
5562 assert(0 <= worker_id && worker_id < limit, "sanity");
5563 assert(!rp->discovery_is_atomic(), "check this code");
5564
5565 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5566 for (uint idx = worker_id; idx < limit; idx += stride) {
5567 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5568
5569 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5570 while (iter.has_next()) {
5571 // Since discovery is not atomic for the CM ref processor, we
5572 // can see some null referent objects.
5573 iter.load_ptrs(DEBUG_ONLY(true));
5574 oop ref = iter.obj();
5575
5576 // This will filter nulls.
5577 if (iter.is_referent_alive()) {
5578 iter.make_referent_alive();
5579 }
5580 iter.move_to_next();
5581 }
5582 }
5583
5584 // Drain the queue - which may cause stealing
5585 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5586 drain_queue.do_void();
5587 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5588 assert(pss.refs()->is_empty(), "should be");
5589 }
5590 };
5591
5592 // Weak Reference processing during an evacuation pause (part 1).
5593 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5594 double ref_proc_start = os::elapsedTime();
5595
5596 ReferenceProcessor* rp = _ref_processor_stw;
5597 assert(rp->discovery_enabled(), "should have been enabled");
5598
5599 // Any reference objects, in the collection set, that were 'discovered'
5600 // by the CM ref processor should have already been copied (either by
5601 // applying the external root copy closure to the discovered lists, or
5602 // by following an RSet entry).
5603 //
5604 // But some of the referents, that are in the collection set, that these
5605 // reference objects point to may not have been copied: the STW ref
5606 // processor would have seen that the reference object had already
5607 // been 'discovered' and would have skipped discovering the reference,
5608 // but would not have treated the reference object as a regular oop.
5609 // As a result the copy closure would not have been applied to the
5610 // referent object.
5611 //
5612 // We need to explicitly copy these referent objects - the references
5613 // will be processed at the end of remarking.
5614 //
5615 // We also need to do this copying before we process the reference
5616 // objects discovered by the STW ref processor in case one of these
5617 // referents points to another object which is also referenced by an
5618 // object discovered by the STW ref processor.
5619
5620 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5621 no_of_gc_workers == workers()->active_workers(),
5622 "Need to reset active GC workers");
5623
5624 set_par_threads(no_of_gc_workers);
5625 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5626 no_of_gc_workers,
5627 _task_queues);
5628
5629 if (G1CollectedHeap::use_parallel_gc_threads()) {
5630 workers()->run_task(&keep_cm_referents);
5631 } else {
5632 keep_cm_referents.work(0);
5633 }
5634
5635 set_par_threads(0);
5636
5637 // Closure to test whether a referent is alive.
5638 G1STWIsAliveClosure is_alive(this);
5639
5640 // Even when parallel reference processing is enabled, the processing
5641 // of JNI refs is serial and performed serially by the current thread
5642 // rather than by a worker. The following PSS will be used for processing
5643 // JNI refs.
5644
5645 // Use only a single queue for this PSS.
5646 G1ParScanThreadState pss(this, 0);
5647
5648 // We do not embed a reference processor in the copying/scanning
5649 // closures while we're actually processing the discovered
5650 // reference objects.
5651 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5652 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5653 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5654
5655 pss.set_evac_closure(&scan_evac_cl);
5656 pss.set_evac_failure_closure(&evac_failure_cl);
5657 pss.set_partial_scan_closure(&partial_scan_cl);
5658
5659 assert(pss.refs()->is_empty(), "pre-condition");
5660
5661 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5662 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5663
5664 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5665 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5666
5667 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5668 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5669
5670 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5671 // We also need to mark copied objects.
5672 copy_non_heap_cl = ©_mark_non_heap_cl;
5673 copy_metadata_cl = ©_mark_metadata_cl;
5674 }
5675
5676 // Keep alive closure.
5677 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5678
5679 // Serial Complete GC closure
5680 G1STWDrainQueueClosure drain_queue(this, &pss);
5681
5682 // Setup the soft refs policy...
5683 rp->setup_policy(false);
5684
5685 ReferenceProcessorStats stats;
5686 if (!rp->processing_is_mt()) {
5687 // Serial reference processing...
5688 stats = rp->process_discovered_references(&is_alive,
5689 &keep_alive,
5690 &drain_queue,
5691 NULL,
5692 _gc_timer_stw);
5693 } else {
5694 // Parallel reference processing
5695 assert(rp->num_q() == no_of_gc_workers, "sanity");
5696 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5697
5698 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5699 stats = rp->process_discovered_references(&is_alive,
5700 &keep_alive,
5701 &drain_queue,
5702 &par_task_executor,
5703 _gc_timer_stw);
5704 }
5705
5706 _gc_tracer_stw->report_gc_reference_stats(stats);
5707 // We have completed copying any necessary live referent objects
5708 // (that were not copied during the actual pause) so we can
5709 // retire any active alloc buffers
5710 pss.retire_alloc_buffers();
5711 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5712
5713 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5714 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5715 }
5716
5717 // Weak Reference processing during an evacuation pause (part 2).
5718 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5719 double ref_enq_start = os::elapsedTime();
5720
5721 ReferenceProcessor* rp = _ref_processor_stw;
5722 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5723
5724 // Now enqueue any remaining on the discovered lists on to
5725 // the pending list.
5726 if (!rp->processing_is_mt()) {
5727 // Serial reference processing...
5728 rp->enqueue_discovered_references();
5729 } else {
5730 // Parallel reference enqueueing
5731
5732 assert(no_of_gc_workers == workers()->active_workers(),
5733 "Need to reset active workers");
5734 assert(rp->num_q() == no_of_gc_workers, "sanity");
5735 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5736
5737 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5738 rp->enqueue_discovered_references(&par_task_executor);
5739 }
5740
5741 rp->verify_no_references_recorded();
5742 assert(!rp->discovery_enabled(), "should have been disabled");
5743
5744 // FIXME
5745 // CM's reference processing also cleans up the string and symbol tables.
5746 // Should we do that here also? We could, but it is a serial operation
5747 // and could significantly increase the pause time.
5748
5749 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5750 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5751 }
5752
5753 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5754 _expand_heap_after_alloc_failure = true;
5755 _evacuation_failed = false;
5756
5757 // Should G1EvacuationFailureALot be in effect for this GC?
5758 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5759
5760 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5761
5762 // Disable the hot card cache.
5763 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5764 hot_card_cache->reset_hot_cache_claimed_index();
5765 hot_card_cache->set_use_cache(false);
5766
5767 uint n_workers;
5768 if (G1CollectedHeap::use_parallel_gc_threads()) {
5769 n_workers =
5770 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5771 workers()->active_workers(),
5772 Threads::number_of_non_daemon_threads());
5773 assert(UseDynamicNumberOfGCThreads ||
5774 n_workers == workers()->total_workers(),
5775 "If not dynamic should be using all the workers");
5776 workers()->set_active_workers(n_workers);
5777 set_par_threads(n_workers);
5778 } else {
5779 assert(n_par_threads() == 0,
5780 "Should be the original non-parallel value");
5781 n_workers = 1;
5782 }
5783
5784 G1ParTask g1_par_task(this, _task_queues);
5785
5786 init_for_evac_failure(NULL);
5787
5788 rem_set()->prepare_for_younger_refs_iterate(true);
5789
5790 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5791 double start_par_time_sec = os::elapsedTime();
5792 double end_par_time_sec;
5793
5794 {
5795 StrongRootsScope srs(this);
5796
5797 if (G1CollectedHeap::use_parallel_gc_threads()) {
5798 // The individual threads will set their evac-failure closures.
5799 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5800 // These tasks use ShareHeap::_process_strong_tasks
5801 assert(UseDynamicNumberOfGCThreads ||
5802 workers()->active_workers() == workers()->total_workers(),
5803 "If not dynamic should be using all the workers");
5804 workers()->run_task(&g1_par_task);
5805 } else {
5806 g1_par_task.set_for_termination(n_workers);
5807 g1_par_task.work(0);
5808 }
5809 end_par_time_sec = os::elapsedTime();
5810
5811 // Closing the inner scope will execute the destructor
5812 // for the StrongRootsScope object. We record the current
5813 // elapsed time before closing the scope so that time
5814 // taken for the SRS destructor is NOT included in the
5815 // reported parallel time.
5816 }
5817
5818 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5819 g1_policy()->phase_times()->record_par_time(par_time_ms);
5820
5821 double code_root_fixup_time_ms =
5822 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5823 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5824
5825 set_par_threads(0);
5826
5827 // Process any discovered reference objects - we have
5828 // to do this _before_ we retire the GC alloc regions
5829 // as we may have to copy some 'reachable' referent
5830 // objects (and their reachable sub-graphs) that were
5831 // not copied during the pause.
5832 process_discovered_references(n_workers);
5833
5834 // Weak root processing.
5835 // Note: when JSR 292 is enabled and code blobs can contain
5836 // non-perm oops then we will need to process the code blobs
5837 // here too.
5838 {
5839 G1STWIsAliveClosure is_alive(this);
5840 G1KeepAliveClosure keep_alive(this);
5841 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5842 }
5843
5844 release_gc_alloc_regions(n_workers, evacuation_info);
5845 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5846
5847 // Reset and re-enable the hot card cache.
5848 // Note the counts for the cards in the regions in the
5849 // collection set are reset when the collection set is freed.
5850 hot_card_cache->reset_hot_cache();
5851 hot_card_cache->set_use_cache(true);
5852
5853 finalize_for_evac_failure();
5854
5855 if (evacuation_failed()) {
5856 remove_self_forwarding_pointers();
5857
5858 // Reset the G1EvacuationFailureALot counters and flags
5859 // Note: the values are reset only when an actual
5860 // evacuation failure occurs.
5861 NOT_PRODUCT(reset_evacuation_should_fail();)
5862 }
5863
5864 // Enqueue any remaining references remaining on the STW
5865 // reference processor's discovered lists. We need to do
5866 // this after the card table is cleaned (and verified) as
5867 // the act of enqueueing entries on to the pending list
5868 // will log these updates (and dirty their associated
5869 // cards). We need these updates logged to update any
5870 // RSets.
5871 enqueue_discovered_references(n_workers);
5872
5873 if (G1DeferredRSUpdate) {
5874 RedirtyLoggedCardTableEntryFastClosure redirty;
5875 dirty_card_queue_set().set_closure(&redirty);
5876 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5877
5878 DirtyCardQueueSet& dcq = concurrent_g1_refine()->cards_ready_for_refinement();
5879 dcq.merge_bufferlists(&dirty_card_queue_set());
5880 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5881 }
5882 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5883 }
5884
5885 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5886 size_t* pre_used,
5887 FreeRegionList* free_list,
5888 OldRegionSet* old_proxy_set,
5889 HumongousRegionSet* humongous_proxy_set,
5890 HRRSCleanupTask* hrrs_cleanup_task,
5891 bool par) {
5892 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5893 if (hr->isHumongous()) {
5894 assert(hr->startsHumongous(), "we should only see starts humongous");
5895 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5896 } else {
5897 _old_set.remove_with_proxy(hr, old_proxy_set);
5898 free_region(hr, pre_used, free_list, par);
5899 }
5900 } else {
5901 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5902 }
5903 }
5904
5905 void G1CollectedHeap::free_region(HeapRegion* hr,
5906 size_t* pre_used,
5907 FreeRegionList* free_list,
5908 bool par) {
5909 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5910 assert(!hr->is_empty(), "the region should not be empty");
5911 assert(free_list != NULL, "pre-condition");
5912
5913 // Clear the card counts for this region.
5914 // Note: we only need to do this if the region is not young
5915 // (since we don't refine cards in young regions).
5916 if (!hr->is_young()) {
5917 _cg1r->hot_card_cache()->reset_card_counts(hr);
5918 }
5919 *pre_used += hr->used();
5920 hr->hr_clear(par, true /* clear_space */);
5921 free_list->add_as_head(hr);
5922 }
5923
5924 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5925 size_t* pre_used,
5926 FreeRegionList* free_list,
5927 HumongousRegionSet* humongous_proxy_set,
5928 bool par) {
5929 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5930 assert(free_list != NULL, "pre-condition");
5931 assert(humongous_proxy_set != NULL, "pre-condition");
5932
5933 size_t hr_used = hr->used();
5934 size_t hr_capacity = hr->capacity();
5935 size_t hr_pre_used = 0;
5936 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5937 // We need to read this before we make the region non-humongous,
5938 // otherwise the information will be gone.
5939 uint last_index = hr->last_hc_index();
5940 hr->set_notHumongous();
5941 free_region(hr, &hr_pre_used, free_list, par);
5942
5943 uint i = hr->hrs_index() + 1;
5944 while (i < last_index) {
5945 HeapRegion* curr_hr = region_at(i);
5946 assert(curr_hr->continuesHumongous(), "invariant");
5947 curr_hr->set_notHumongous();
5948 free_region(curr_hr, &hr_pre_used, free_list, par);
5949 i += 1;
5950 }
5951 assert(hr_pre_used == hr_used,
5952 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5953 "should be the same", hr_pre_used, hr_used));
5954 *pre_used += hr_pre_used;
5955 }
5956
5957 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5958 FreeRegionList* free_list,
5959 OldRegionSet* old_proxy_set,
5960 HumongousRegionSet* humongous_proxy_set,
5961 bool par) {
5962 if (pre_used > 0) {
5963 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5964 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5965 assert(_summary_bytes_used >= pre_used,
5966 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5967 "should be >= pre_used: "SIZE_FORMAT,
5968 _summary_bytes_used, pre_used));
5969 _summary_bytes_used -= pre_used;
5970 }
5971 if (free_list != NULL && !free_list->is_empty()) {
5972 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5973 _free_list.add_as_head(free_list);
5974 }
5975 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5976 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5977 _old_set.update_from_proxy(old_proxy_set);
5978 }
5979 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5980 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5981 _humongous_set.update_from_proxy(humongous_proxy_set);
5982 }
5983 }
5984
5985 class G1ParCleanupCTTask : public AbstractGangTask {
5986 CardTableModRefBS* _ct_bs;
5987 G1CollectedHeap* _g1h;
5988 HeapRegion* volatile _su_head;
5989 public:
5990 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5991 G1CollectedHeap* g1h) :
5992 AbstractGangTask("G1 Par Cleanup CT Task"),
5993 _ct_bs(ct_bs), _g1h(g1h) { }
5994
5995 void work(uint worker_id) {
5996 HeapRegion* r;
5997 while (r = _g1h->pop_dirty_cards_region()) {
5998 clear_cards(r);
5999 }
6000 }
6001
6002 void clear_cards(HeapRegion* r) {
6003 // Cards of the survivors should have already been dirtied.
6004 if (!r->is_survivor()) {
6005 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6006 }
6007 }
6008 };
6009
6010 #ifndef PRODUCT
6011 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6012 G1CollectedHeap* _g1h;
6013 CardTableModRefBS* _ct_bs;
6014 public:
6015 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
6016 : _g1h(g1h), _ct_bs(ct_bs) { }
6017 virtual bool doHeapRegion(HeapRegion* r) {
6018 if (r->is_survivor()) {
6019 _g1h->verify_dirty_region(r);
6020 } else {
6021 _g1h->verify_not_dirty_region(r);
6022 }
6023 return false;
6024 }
6025 };
6026
6027 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6028 // All of the region should be clean.
6029 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
6030 MemRegion mr(hr->bottom(), hr->end());
6031 ct_bs->verify_not_dirty_region(mr);
6032 }
6033
6034 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6035 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6036 // dirty allocated blocks as they allocate them. The thread that
6037 // retires each region and replaces it with a new one will do a
6038 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6039 // not dirty that area (one less thing to have to do while holding
6040 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6041 // is dirty.
6042 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
6043 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6044 ct_bs->verify_dirty_region(mr);
6045 }
6046
6047 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6048 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
6049 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6050 verify_dirty_region(hr);
6051 }
6052 }
6053
6054 void G1CollectedHeap::verify_dirty_young_regions() {
6055 verify_dirty_young_list(_young_list->first_region());
6056 }
6057 #endif
6058
6059 void G1CollectedHeap::cleanUpCardTable() {
6060 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
6061 double start = os::elapsedTime();
6062
6063 {
6064 // Iterate over the dirty cards region list.
6065 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6066
6067 if (G1CollectedHeap::use_parallel_gc_threads()) {
6068 set_par_threads();
6069 workers()->run_task(&cleanup_task);
6070 set_par_threads(0);
6071 } else {
6072 while (_dirty_cards_region_list) {
6073 HeapRegion* r = _dirty_cards_region_list;
6074 cleanup_task.clear_cards(r);
6075 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6076 if (_dirty_cards_region_list == r) {
6077 // The last region.
6078 _dirty_cards_region_list = NULL;
6079 }
6080 r->set_next_dirty_cards_region(NULL);
6081 }
6082 }
6083 #ifndef PRODUCT
6084 if (G1VerifyCTCleanup || VerifyAfterGC) {
6085 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6086 heap_region_iterate(&cleanup_verifier);
6087 }
6088 #endif
6089 }
6090
6091 double elapsed = os::elapsedTime() - start;
6092 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6093 }
6094
6095 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6096 size_t pre_used = 0;
6097 FreeRegionList local_free_list("Local List for CSet Freeing");
6098
6099 double young_time_ms = 0.0;
6100 double non_young_time_ms = 0.0;
6101
6102 // Since the collection set is a superset of the the young list,
6103 // all we need to do to clear the young list is clear its
6104 // head and length, and unlink any young regions in the code below
6105 _young_list->clear();
6106
6107 G1CollectorPolicy* policy = g1_policy();
6108
6109 double start_sec = os::elapsedTime();
6110 bool non_young = true;
6111
6112 HeapRegion* cur = cs_head;
6113 int age_bound = -1;
6114 size_t rs_lengths = 0;
6115
6116 while (cur != NULL) {
6117 assert(!is_on_master_free_list(cur), "sanity");
6118 if (non_young) {
6119 if (cur->is_young()) {
6120 double end_sec = os::elapsedTime();
6121 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6122 non_young_time_ms += elapsed_ms;
6123
6124 start_sec = os::elapsedTime();
6125 non_young = false;
6126 }
6127 } else {
6128 if (!cur->is_young()) {
6129 double end_sec = os::elapsedTime();
6130 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6131 young_time_ms += elapsed_ms;
6132
6133 start_sec = os::elapsedTime();
6134 non_young = true;
6135 }
6136 }
6137
6138 rs_lengths += cur->rem_set()->occupied();
6139
6140 HeapRegion* next = cur->next_in_collection_set();
6141 assert(cur->in_collection_set(), "bad CS");
6142 cur->set_next_in_collection_set(NULL);
6143 cur->set_in_collection_set(false);
6144
6145 if (cur->is_young()) {
6146 int index = cur->young_index_in_cset();
6147 assert(index != -1, "invariant");
6148 assert((uint) index < policy->young_cset_region_length(), "invariant");
6149 size_t words_survived = _surviving_young_words[index];
6150 cur->record_surv_words_in_group(words_survived);
6151
6152 // At this point the we have 'popped' cur from the collection set
6153 // (linked via next_in_collection_set()) but it is still in the
6154 // young list (linked via next_young_region()). Clear the
6155 // _next_young_region field.
6156 cur->set_next_young_region(NULL);
6157 } else {
6158 int index = cur->young_index_in_cset();
6159 assert(index == -1, "invariant");
6160 }
6161
6162 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6163 (!cur->is_young() && cur->young_index_in_cset() == -1),
6164 "invariant" );
6165
6166 if (!cur->evacuation_failed()) {
6167 MemRegion used_mr = cur->used_region();
6168
6169 // And the region is empty.
6170 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6171 free_region(cur, &pre_used, &local_free_list, false /* par */);
6172 } else {
6173 cur->uninstall_surv_rate_group();
6174 if (cur->is_young()) {
6175 cur->set_young_index_in_cset(-1);
6176 }
6177 cur->set_not_young();
6178 cur->set_evacuation_failed(false);
6179 // The region is now considered to be old.
6180 _old_set.add(cur);
6181 evacuation_info.increment_collectionset_used_after(cur->used());
6182 }
6183 cur = next;
6184 }
6185
6186 evacuation_info.set_regions_freed(local_free_list.length());
6187 policy->record_max_rs_lengths(rs_lengths);
6188 policy->cset_regions_freed();
6189
6190 double end_sec = os::elapsedTime();
6191 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6192
6193 if (non_young) {
6194 non_young_time_ms += elapsed_ms;
6195 } else {
6196 young_time_ms += elapsed_ms;
6197 }
6198
6199 update_sets_after_freeing_regions(pre_used, &local_free_list,
6200 NULL /* old_proxy_set */,
6201 NULL /* humongous_proxy_set */,
6202 false /* par */);
6203 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6204 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6205 }
6206
6207 // This routine is similar to the above but does not record
6208 // any policy statistics or update free lists; we are abandoning
6209 // the current incremental collection set in preparation of a
6210 // full collection. After the full GC we will start to build up
6211 // the incremental collection set again.
6212 // This is only called when we're doing a full collection
6213 // and is immediately followed by the tearing down of the young list.
6214
6215 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6216 HeapRegion* cur = cs_head;
6217
6218 while (cur != NULL) {
6219 HeapRegion* next = cur->next_in_collection_set();
6220 assert(cur->in_collection_set(), "bad CS");
6221 cur->set_next_in_collection_set(NULL);
6222 cur->set_in_collection_set(false);
6223 cur->set_young_index_in_cset(-1);
6224 cur = next;
6225 }
6226 }
6227
6228 void G1CollectedHeap::set_free_regions_coming() {
6229 if (G1ConcRegionFreeingVerbose) {
6230 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6231 "setting free regions coming");
6232 }
6233
6234 assert(!free_regions_coming(), "pre-condition");
6235 _free_regions_coming = true;
6236 }
6237
6238 void G1CollectedHeap::reset_free_regions_coming() {
6239 assert(free_regions_coming(), "pre-condition");
6240
6241 {
6242 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6243 _free_regions_coming = false;
6244 SecondaryFreeList_lock->notify_all();
6245 }
6246
6247 if (G1ConcRegionFreeingVerbose) {
6248 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6249 "reset free regions coming");
6250 }
6251 }
6252
6253 void G1CollectedHeap::wait_while_free_regions_coming() {
6254 // Most of the time we won't have to wait, so let's do a quick test
6255 // first before we take the lock.
6256 if (!free_regions_coming()) {
6257 return;
6258 }
6259
6260 if (G1ConcRegionFreeingVerbose) {
6261 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6262 "waiting for free regions");
6263 }
6264
6265 {
6266 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6267 while (free_regions_coming()) {
6268 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6269 }
6270 }
6271
6272 if (G1ConcRegionFreeingVerbose) {
6273 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6274 "done waiting for free regions");
6275 }
6276 }
6277
6278 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6279 assert(heap_lock_held_for_gc(),
6280 "the heap lock should already be held by or for this thread");
6281 _young_list->push_region(hr);
6282 }
6283
6284 class NoYoungRegionsClosure: public HeapRegionClosure {
6285 private:
6286 bool _success;
6287 public:
6288 NoYoungRegionsClosure() : _success(true) { }
6289 bool doHeapRegion(HeapRegion* r) {
6290 if (r->is_young()) {
6291 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6292 r->bottom(), r->end());
6293 _success = false;
6294 }
6295 return false;
6296 }
6297 bool success() { return _success; }
6298 };
6299
6300 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6301 bool ret = _young_list->check_list_empty(check_sample);
6302
6303 if (check_heap) {
6304 NoYoungRegionsClosure closure;
6305 heap_region_iterate(&closure);
6306 ret = ret && closure.success();
6307 }
6308
6309 return ret;
6310 }
6311
6312 class TearDownRegionSetsClosure : public HeapRegionClosure {
6313 private:
6314 OldRegionSet *_old_set;
6315
6316 public:
6317 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6318
6319 bool doHeapRegion(HeapRegion* r) {
6320 if (r->is_empty()) {
6321 // We ignore empty regions, we'll empty the free list afterwards
6322 } else if (r->is_young()) {
6323 // We ignore young regions, we'll empty the young list afterwards
6324 } else if (r->isHumongous()) {
6325 // We ignore humongous regions, we're not tearing down the
6326 // humongous region set
6327 } else {
6328 // The rest should be old
6329 _old_set->remove(r);
6330 }
6331 return false;
6332 }
6333
6334 ~TearDownRegionSetsClosure() {
6335 assert(_old_set->is_empty(), "post-condition");
6336 }
6337 };
6338
6339 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6340 assert_at_safepoint(true /* should_be_vm_thread */);
6341
6342 if (!free_list_only) {
6343 TearDownRegionSetsClosure cl(&_old_set);
6344 heap_region_iterate(&cl);
6345
6346 // Need to do this after the heap iteration to be able to
6347 // recognize the young regions and ignore them during the iteration.
6348 _young_list->empty_list();
6349 }
6350 _free_list.remove_all();
6351 }
6352
6353 class RebuildRegionSetsClosure : public HeapRegionClosure {
6354 private:
6355 bool _free_list_only;
6356 OldRegionSet* _old_set;
6357 FreeRegionList* _free_list;
6358 size_t _total_used;
6359
6360 public:
6361 RebuildRegionSetsClosure(bool free_list_only,
6362 OldRegionSet* old_set, FreeRegionList* free_list) :
6363 _free_list_only(free_list_only),
6364 _old_set(old_set), _free_list(free_list), _total_used(0) {
6365 assert(_free_list->is_empty(), "pre-condition");
6366 if (!free_list_only) {
6367 assert(_old_set->is_empty(), "pre-condition");
6368 }
6369 }
6370
6371 bool doHeapRegion(HeapRegion* r) {
6372 if (r->continuesHumongous()) {
6373 return false;
6374 }
6375
6376 if (r->is_empty()) {
6377 // Add free regions to the free list
6378 _free_list->add_as_tail(r);
6379 } else if (!_free_list_only) {
6380 assert(!r->is_young(), "we should not come across young regions");
6381
6382 if (r->isHumongous()) {
6383 // We ignore humongous regions, we left the humongous set unchanged
6384 } else {
6385 // The rest should be old, add them to the old set
6386 _old_set->add(r);
6387 }
6388 _total_used += r->used();
6389 }
6390
6391 return false;
6392 }
6393
6394 size_t total_used() {
6395 return _total_used;
6396 }
6397 };
6398
6399 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6400 assert_at_safepoint(true /* should_be_vm_thread */);
6401
6402 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6403 heap_region_iterate(&cl);
6404
6405 if (!free_list_only) {
6406 _summary_bytes_used = cl.total_used();
6407 }
6408 assert(_summary_bytes_used == recalculate_used(),
6409 err_msg("inconsistent _summary_bytes_used, "
6410 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6411 _summary_bytes_used, recalculate_used()));
6412 }
6413
6414 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6415 _refine_cte_cl->set_concurrent(concurrent);
6416 }
6417
6418 void G1CollectedHeap::set_use_transferring_cte_cl(bool transferring) {
6419 CardTableEntryClosure* cte_cl = NULL;
6420 if (transferring) {
6421 cte_cl = _transfer_cte_cl;
6422 } else {
6423 cte_cl = _refine_cte_cl;
6424 }
6425 JavaThread::dirty_card_queue_set().set_closure(cte_cl);
6426 }
6427
6428
6429 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6430 HeapRegion* hr = heap_region_containing(p);
6431 if (hr == NULL) {
6432 return false;
6433 } else {
6434 return hr->is_in(p);
6435 }
6436 }
6437
6438 // Methods for the mutator alloc region
6439
6440 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6441 bool force) {
6442 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6443 assert(!force || g1_policy()->can_expand_young_list(),
6444 "if force is true we should be able to expand the young list");
6445 bool young_list_full = g1_policy()->is_young_list_full();
6446 if (force || !young_list_full) {
6447 HeapRegion* new_alloc_region = new_region(word_size,
6448 false /* do_expand */);
6449 if (new_alloc_region != NULL) {
6450 set_region_short_lived_locked(new_alloc_region);
6451 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6452 return new_alloc_region;
6453 }
6454 }
6455 return NULL;
6456 }
6457
6458 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6459 size_t allocated_bytes) {
6460 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6461 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6462
6463 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6464 _summary_bytes_used += allocated_bytes;
6465 _hr_printer.retire(alloc_region);
6466 // We update the eden sizes here, when the region is retired,
6467 // instead of when it's allocated, since this is the point that its
6468 // used space has been recored in _summary_bytes_used.
6469 g1mm()->update_eden_size();
6470 }
6471
6472 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6473 bool force) {
6474 return _g1h->new_mutator_alloc_region(word_size, force);
6475 }
6476
6477 void G1CollectedHeap::set_par_threads() {
6478 // Don't change the number of workers. Use the value previously set
6479 // in the workgroup.
6480 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6481 uint n_workers = workers()->active_workers();
6482 assert(UseDynamicNumberOfGCThreads ||
6483 n_workers == workers()->total_workers(),
6484 "Otherwise should be using the total number of workers");
6485 if (n_workers == 0) {
6486 assert(false, "Should have been set in prior evacuation pause.");
6487 n_workers = ParallelGCThreads;
6488 workers()->set_active_workers(n_workers);
6489 }
6490 set_par_threads(n_workers);
6491 }
6492
6493 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6494 size_t allocated_bytes) {
6495 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6496 }
6497
6498 // Methods for the GC alloc regions
6499
6500 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6501 uint count,
6502 GCAllocPurpose ap) {
6503 assert(FreeList_lock->owned_by_self(), "pre-condition");
6504
6505 if (count < g1_policy()->max_regions(ap)) {
6506 HeapRegion* new_alloc_region = new_region(word_size,
6507 true /* do_expand */);
6508 if (new_alloc_region != NULL) {
6509 // We really only need to do this for old regions given that we
6510 // should never scan survivors. But it doesn't hurt to do it
6511 // for survivors too.
6512 new_alloc_region->set_saved_mark();
6513 if (ap == GCAllocForSurvived) {
6514 new_alloc_region->set_survivor();
6515 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6516 } else {
6517 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6518 }
6519 bool during_im = g1_policy()->during_initial_mark_pause();
6520 new_alloc_region->note_start_of_copying(during_im);
6521 return new_alloc_region;
6522 } else {
6523 g1_policy()->note_alloc_region_limit_reached(ap);
6524 }
6525 }
6526 return NULL;
6527 }
6528
6529 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6530 size_t allocated_bytes,
6531 GCAllocPurpose ap) {
6532 bool during_im = g1_policy()->during_initial_mark_pause();
6533 alloc_region->note_end_of_copying(during_im);
6534 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6535 if (ap == GCAllocForSurvived) {
6536 young_list()->add_survivor_region(alloc_region);
6537 } else {
6538 _old_set.add(alloc_region);
6539 }
6540 _hr_printer.retire(alloc_region);
6541 }
6542
6543 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6544 bool force) {
6545 assert(!force, "not supported for GC alloc regions");
6546 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6547 }
6548
6549 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6550 size_t allocated_bytes) {
6551 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6552 GCAllocForSurvived);
6553 }
6554
6555 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6556 bool force) {
6557 assert(!force, "not supported for GC alloc regions");
6558 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6559 }
6560
6561 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6562 size_t allocated_bytes) {
6563 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6564 GCAllocForTenured);
6565 }
6566 // Heap region set verification
6567
6568 class VerifyRegionListsClosure : public HeapRegionClosure {
6569 private:
6570 FreeRegionList* _free_list;
6571 OldRegionSet* _old_set;
6572 HumongousRegionSet* _humongous_set;
6573 uint _region_count;
6574
6575 public:
6576 VerifyRegionListsClosure(OldRegionSet* old_set,
6577 HumongousRegionSet* humongous_set,
6578 FreeRegionList* free_list) :
6579 _old_set(old_set), _humongous_set(humongous_set),
6580 _free_list(free_list), _region_count(0) { }
6581
6582 uint region_count() { return _region_count; }
6583
6584 bool doHeapRegion(HeapRegion* hr) {
6585 _region_count += 1;
6586
6587 if (hr->continuesHumongous()) {
6588 return false;
6589 }
6590
6591 if (hr->is_young()) {
6592 // TODO
6593 } else if (hr->startsHumongous()) {
6594 _humongous_set->verify_next_region(hr);
6595 } else if (hr->is_empty()) {
6596 _free_list->verify_next_region(hr);
6597 } else {
6598 _old_set->verify_next_region(hr);
6599 }
6600 return false;
6601 }
6602 };
6603
6604 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6605 HeapWord* bottom) {
6606 HeapWord* end = bottom + HeapRegion::GrainWords;
6607 MemRegion mr(bottom, end);
6608 assert(_g1_reserved.contains(mr), "invariant");
6609 // This might return NULL if the allocation fails
6610 return new HeapRegion(hrs_index, _bot_shared, mr);
6611 }
6612
6613 void G1CollectedHeap::verify_region_sets() {
6614 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6615
6616 // First, check the explicit lists.
6617 _free_list.verify();
6618 {
6619 // Given that a concurrent operation might be adding regions to
6620 // the secondary free list we have to take the lock before
6621 // verifying it.
6622 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6623 _secondary_free_list.verify();
6624 }
6625 _old_set.verify();
6626 _humongous_set.verify();
6627
6628 // If a concurrent region freeing operation is in progress it will
6629 // be difficult to correctly attributed any free regions we come
6630 // across to the correct free list given that they might belong to
6631 // one of several (free_list, secondary_free_list, any local lists,
6632 // etc.). So, if that's the case we will skip the rest of the
6633 // verification operation. Alternatively, waiting for the concurrent
6634 // operation to complete will have a non-trivial effect on the GC's
6635 // operation (no concurrent operation will last longer than the
6636 // interval between two calls to verification) and it might hide
6637 // any issues that we would like to catch during testing.
6638 if (free_regions_coming()) {
6639 return;
6640 }
6641
6642 // Make sure we append the secondary_free_list on the free_list so
6643 // that all free regions we will come across can be safely
6644 // attributed to the free_list.
6645 append_secondary_free_list_if_not_empty_with_lock();
6646
6647 // Finally, make sure that the region accounting in the lists is
6648 // consistent with what we see in the heap.
6649 _old_set.verify_start();
6650 _humongous_set.verify_start();
6651 _free_list.verify_start();
6652
6653 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6654 heap_region_iterate(&cl);
6655
6656 _old_set.verify_end();
6657 _humongous_set.verify_end();
6658 _free_list.verify_end();
6659 }