1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1StringDedup.hpp"
43 #include "gc_implementation/g1/g1YCTypes.hpp"
44 #include "gc_implementation/g1/heapRegion.inline.hpp"
45 #include "gc_implementation/g1/heapRegionRemSet.hpp"
46 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
47 #include "gc_implementation/g1/vm_operations_g1.hpp"
48 #include "gc_implementation/shared/gcHeapSummary.hpp"
49 #include "gc_implementation/shared/gcTimer.hpp"
50 #include "gc_implementation/shared/gcTrace.hpp"
51 #include "gc_implementation/shared/gcTraceTime.hpp"
52 #include "gc_implementation/shared/isGCActiveMark.hpp"
53 #include "memory/gcLocker.inline.hpp"
54 #include "memory/generationSpec.hpp"
55 #include "memory/iterator.hpp"
56 #include "memory/referenceProcessor.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/oop.pcgc.inline.hpp"
59 #include "runtime/vmThread.hpp"
60 #include "utilities/ticks.hpp"
61
62 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
63
64 // turn it on so that the contents of the young list (scan-only /
65 // to-be-collected) are printed at "strategic" points before / during
66 // / after the collection --- this is useful for debugging
67 #define YOUNG_LIST_VERBOSE 0
68 // CURRENT STATUS
69 // This file is under construction. Search for "FIXME".
70
71 // INVARIANTS/NOTES
72 //
73 // All allocation activity covered by the G1CollectedHeap interface is
74 // serialized by acquiring the HeapLock. This happens in mem_allocate
75 // and allocate_new_tlab, which are the "entry" points to the
76 // allocation code from the rest of the JVM. (Note that this does not
77 // apply to TLAB allocation, which is not part of this interface: it
78 // is done by clients of this interface.)
79
80 // Notes on implementation of parallelism in different tasks.
81 //
82 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
83 // The number of GC workers is passed to heap_region_par_iterate_chunked().
84 // It does use run_task() which sets _n_workers in the task.
85 // G1ParTask executes g1_process_strong_roots() ->
86 // SharedHeap::process_strong_roots() which calls eventually to
87 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
88 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
89 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
90 //
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 G1RemSet* _g1rs;
96 ConcurrentG1Refine* _cg1r;
97 bool _concurrent;
98 public:
99 RefineCardTableEntryClosure(G1RemSet* g1rs,
100 ConcurrentG1Refine* cg1r) :
101 _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
102 {}
103 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
104 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
105 // This path is executed by the concurrent refine or mutator threads,
106 // concurrently, and so we do not care if card_ptr contains references
107 // that point into the collection set.
108 assert(!oops_into_cset, "should be");
109
110 if (_concurrent && SuspendibleThreadSet::should_yield()) {
111 // Caller will actually yield.
112 return false;
113 }
114 // Otherwise, we finished successfully; return true.
115 return true;
116 }
117 void set_concurrent(bool b) { _concurrent = b; }
118 };
119
120
121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
122 int _calls;
123 G1CollectedHeap* _g1h;
124 CardTableModRefBS* _ctbs;
125 int _histo[256];
126 public:
127 ClearLoggedCardTableEntryClosure() :
128 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
129 {
130 for (int i = 0; i < 256; i++) _histo[i] = 0;
131 }
132 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
133 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
134 _calls++;
135 unsigned char* ujb = (unsigned char*)card_ptr;
136 int ind = (int)(*ujb);
137 _histo[ind]++;
138 *card_ptr = -1;
139 }
140 return true;
141 }
142 int calls() { return _calls; }
143 void print_histo() {
144 gclog_or_tty->print_cr("Card table value histogram:");
145 for (int i = 0; i < 256; i++) {
146 if (_histo[i] != 0) {
147 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
148 }
149 }
150 }
151 };
152
153 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
154 int _calls;
155 G1CollectedHeap* _g1h;
156 CardTableModRefBS* _ctbs;
157 public:
158 RedirtyLoggedCardTableEntryClosure() :
159 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
160
161 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
162 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
163 _calls++;
164 *card_ptr = 0;
165 }
166 return true;
167 }
168 int calls() { return _calls; }
169 };
170
171 YoungList::YoungList(G1CollectedHeap* g1h) :
172 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
173 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
174 guarantee(check_list_empty(false), "just making sure...");
175 }
176
177 void YoungList::push_region(HeapRegion *hr) {
178 assert(!hr->is_young(), "should not already be young");
179 assert(hr->get_next_young_region() == NULL, "cause it should!");
180
181 hr->set_next_young_region(_head);
182 _head = hr;
183
184 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
185 ++_length;
186 }
187
188 void YoungList::add_survivor_region(HeapRegion* hr) {
189 assert(hr->is_survivor(), "should be flagged as survivor region");
190 assert(hr->get_next_young_region() == NULL, "cause it should!");
191
192 hr->set_next_young_region(_survivor_head);
193 if (_survivor_head == NULL) {
194 _survivor_tail = hr;
195 }
196 _survivor_head = hr;
197 ++_survivor_length;
198 }
199
200 void YoungList::empty_list(HeapRegion* list) {
201 while (list != NULL) {
202 HeapRegion* next = list->get_next_young_region();
203 list->set_next_young_region(NULL);
204 list->uninstall_surv_rate_group();
205 list->set_not_young();
206 list = next;
207 }
208 }
209
210 void YoungList::empty_list() {
211 assert(check_list_well_formed(), "young list should be well formed");
212
213 empty_list(_head);
214 _head = NULL;
215 _length = 0;
216
217 empty_list(_survivor_head);
218 _survivor_head = NULL;
219 _survivor_tail = NULL;
220 _survivor_length = 0;
221
222 _last_sampled_rs_lengths = 0;
223
224 assert(check_list_empty(false), "just making sure...");
225 }
226
227 bool YoungList::check_list_well_formed() {
228 bool ret = true;
229
230 uint length = 0;
231 HeapRegion* curr = _head;
232 HeapRegion* last = NULL;
233 while (curr != NULL) {
234 if (!curr->is_young()) {
235 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
236 "incorrectly tagged (y: %d, surv: %d)",
237 curr->bottom(), curr->end(),
238 curr->is_young(), curr->is_survivor());
239 ret = false;
240 }
241 ++length;
242 last = curr;
243 curr = curr->get_next_young_region();
244 }
245 ret = ret && (length == _length);
246
247 if (!ret) {
248 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
249 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
250 length, _length);
251 }
252
253 return ret;
254 }
255
256 bool YoungList::check_list_empty(bool check_sample) {
257 bool ret = true;
258
259 if (_length != 0) {
260 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
261 _length);
262 ret = false;
263 }
264 if (check_sample && _last_sampled_rs_lengths != 0) {
265 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
266 ret = false;
267 }
268 if (_head != NULL) {
269 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
270 ret = false;
271 }
272 if (!ret) {
273 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
274 }
275
276 return ret;
277 }
278
279 void
280 YoungList::rs_length_sampling_init() {
281 _sampled_rs_lengths = 0;
282 _curr = _head;
283 }
284
285 bool
286 YoungList::rs_length_sampling_more() {
287 return _curr != NULL;
288 }
289
290 void
291 YoungList::rs_length_sampling_next() {
292 assert( _curr != NULL, "invariant" );
293 size_t rs_length = _curr->rem_set()->occupied();
294
295 _sampled_rs_lengths += rs_length;
296
297 // The current region may not yet have been added to the
298 // incremental collection set (it gets added when it is
299 // retired as the current allocation region).
300 if (_curr->in_collection_set()) {
301 // Update the collection set policy information for this region
302 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
303 }
304
305 _curr = _curr->get_next_young_region();
306 if (_curr == NULL) {
307 _last_sampled_rs_lengths = _sampled_rs_lengths;
308 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
309 }
310 }
311
312 void
313 YoungList::reset_auxilary_lists() {
314 guarantee( is_empty(), "young list should be empty" );
315 assert(check_list_well_formed(), "young list should be well formed");
316
317 // Add survivor regions to SurvRateGroup.
318 _g1h->g1_policy()->note_start_adding_survivor_regions();
319 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
320
321 int young_index_in_cset = 0;
322 for (HeapRegion* curr = _survivor_head;
323 curr != NULL;
324 curr = curr->get_next_young_region()) {
325 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
326
327 // The region is a non-empty survivor so let's add it to
328 // the incremental collection set for the next evacuation
329 // pause.
330 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
331 young_index_in_cset += 1;
332 }
333 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
334 _g1h->g1_policy()->note_stop_adding_survivor_regions();
335
336 _head = _survivor_head;
337 _length = _survivor_length;
338 if (_survivor_head != NULL) {
339 assert(_survivor_tail != NULL, "cause it shouldn't be");
340 assert(_survivor_length > 0, "invariant");
341 _survivor_tail->set_next_young_region(NULL);
342 }
343
344 // Don't clear the survivor list handles until the start of
345 // the next evacuation pause - we need it in order to re-tag
346 // the survivor regions from this evacuation pause as 'young'
347 // at the start of the next.
348
349 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
350
351 assert(check_list_well_formed(), "young list should be well formed");
352 }
353
354 void YoungList::print() {
355 HeapRegion* lists[] = {_head, _survivor_head};
356 const char* names[] = {"YOUNG", "SURVIVOR"};
357
358 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
359 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
360 HeapRegion *curr = lists[list];
361 if (curr == NULL)
362 gclog_or_tty->print_cr(" empty");
363 while (curr != NULL) {
364 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
365 HR_FORMAT_PARAMS(curr),
366 curr->prev_top_at_mark_start(),
367 curr->next_top_at_mark_start(),
368 curr->age_in_surv_rate_group_cond());
369 curr = curr->get_next_young_region();
370 }
371 }
372
373 gclog_or_tty->print_cr("");
374 }
375
376 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
377 {
378 // Claim the right to put the region on the dirty cards region list
379 // by installing a self pointer.
380 HeapRegion* next = hr->get_next_dirty_cards_region();
381 if (next == NULL) {
382 HeapRegion* res = (HeapRegion*)
383 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
384 NULL);
385 if (res == NULL) {
386 HeapRegion* head;
387 do {
388 // Put the region to the dirty cards region list.
389 head = _dirty_cards_region_list;
390 next = (HeapRegion*)
391 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
392 if (next == head) {
393 assert(hr->get_next_dirty_cards_region() == hr,
394 "hr->get_next_dirty_cards_region() != hr");
395 if (next == NULL) {
396 // The last region in the list points to itself.
397 hr->set_next_dirty_cards_region(hr);
398 } else {
399 hr->set_next_dirty_cards_region(next);
400 }
401 }
402 } while (next != head);
403 }
404 }
405 }
406
407 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
408 {
409 HeapRegion* head;
410 HeapRegion* hr;
411 do {
412 head = _dirty_cards_region_list;
413 if (head == NULL) {
414 return NULL;
415 }
416 HeapRegion* new_head = head->get_next_dirty_cards_region();
417 if (head == new_head) {
418 // The last region.
419 new_head = NULL;
420 }
421 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
422 head);
423 } while (hr != head);
424 assert(hr != NULL, "invariant");
425 hr->set_next_dirty_cards_region(NULL);
426 return hr;
427 }
428
429 void G1CollectedHeap::stop_conc_gc_threads() {
430 _cg1r->stop();
431 _cmThread->stop();
432 if (G1StringDedup::is_enabled()) {
433 G1StringDedup::stop();
434 }
435 }
436
437 #ifdef ASSERT
438 // A region is added to the collection set as it is retired
439 // so an address p can point to a region which will be in the
440 // collection set but has not yet been retired. This method
441 // therefore is only accurate during a GC pause after all
442 // regions have been retired. It is used for debugging
443 // to check if an nmethod has references to objects that can
444 // be move during a partial collection. Though it can be
445 // inaccurate, it is sufficient for G1 because the conservative
446 // implementation of is_scavengable() for G1 will indicate that
447 // all nmethods must be scanned during a partial collection.
448 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
449 HeapRegion* hr = heap_region_containing(p);
450 return hr != NULL && hr->in_collection_set();
451 }
452 #endif
453
454 // Returns true if the reference points to an object that
455 // can move in an incremental collection.
456 bool G1CollectedHeap::is_scavengable(const void* p) {
457 G1CollectedHeap* g1h = G1CollectedHeap::heap();
458 G1CollectorPolicy* g1p = g1h->g1_policy();
459 HeapRegion* hr = heap_region_containing(p);
460 if (hr == NULL) {
461 // null
462 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
463 return false;
464 } else {
465 return !hr->isHumongous();
466 }
467 }
468
469 void G1CollectedHeap::check_ct_logs_at_safepoint() {
470 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
471 CardTableModRefBS* ct_bs = g1_barrier_set();
472
473 // Count the dirty cards at the start.
474 CountNonCleanMemRegionClosure count1(this);
475 ct_bs->mod_card_iterate(&count1);
476 int orig_count = count1.n();
477
478 // First clear the logged cards.
479 ClearLoggedCardTableEntryClosure clear;
480 dcqs.set_closure(&clear);
481 dcqs.apply_closure_to_all_completed_buffers();
482 dcqs.iterate_closure_all_threads(false);
483 clear.print_histo();
484
485 // Now ensure that there's no dirty cards.
486 CountNonCleanMemRegionClosure count2(this);
487 ct_bs->mod_card_iterate(&count2);
488 if (count2.n() != 0) {
489 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
490 count2.n(), orig_count);
491 }
492 guarantee(count2.n() == 0, "Card table should be clean.");
493
494 RedirtyLoggedCardTableEntryClosure redirty;
495 JavaThread::dirty_card_queue_set().set_closure(&redirty);
496 dcqs.apply_closure_to_all_completed_buffers();
497 dcqs.iterate_closure_all_threads(false);
498 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
499 clear.calls(), orig_count);
500 guarantee(redirty.calls() == clear.calls(),
501 "Or else mechanism is broken.");
502
503 CountNonCleanMemRegionClosure count3(this);
504 ct_bs->mod_card_iterate(&count3);
505 if (count3.n() != orig_count) {
506 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
507 orig_count, count3.n());
508 guarantee(count3.n() >= orig_count, "Should have restored them all.");
509 }
510
511 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
512 }
513
514 // Private class members.
515
516 G1CollectedHeap* G1CollectedHeap::_g1h;
517
518 // Private methods.
519
520 HeapRegion*
521 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
522 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
523 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
524 if (!_secondary_free_list.is_empty()) {
525 if (G1ConcRegionFreeingVerbose) {
526 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
527 "secondary_free_list has %u entries",
528 _secondary_free_list.length());
529 }
530 // It looks as if there are free regions available on the
531 // secondary_free_list. Let's move them to the free_list and try
532 // again to allocate from it.
533 append_secondary_free_list();
534
535 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
536 "empty we should have moved at least one entry to the free_list");
537 HeapRegion* res = _free_list.remove_region(is_old);
538 if (G1ConcRegionFreeingVerbose) {
539 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
540 "allocated "HR_FORMAT" from secondary_free_list",
541 HR_FORMAT_PARAMS(res));
542 }
543 return res;
544 }
545
546 // Wait here until we get notified either when (a) there are no
547 // more free regions coming or (b) some regions have been moved on
548 // the secondary_free_list.
549 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
550 }
551
552 if (G1ConcRegionFreeingVerbose) {
553 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
554 "could not allocate from secondary_free_list");
555 }
556 return NULL;
557 }
558
559 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
560 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
561 "the only time we use this to allocate a humongous region is "
562 "when we are allocating a single humongous region");
563
564 HeapRegion* res;
565 if (G1StressConcRegionFreeing) {
566 if (!_secondary_free_list.is_empty()) {
567 if (G1ConcRegionFreeingVerbose) {
568 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
569 "forced to look at the secondary_free_list");
570 }
571 res = new_region_try_secondary_free_list(is_old);
572 if (res != NULL) {
573 return res;
574 }
575 }
576 }
577
578 res = _free_list.remove_region(is_old);
579
580 if (res == NULL) {
581 if (G1ConcRegionFreeingVerbose) {
582 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
583 "res == NULL, trying the secondary_free_list");
584 }
585 res = new_region_try_secondary_free_list(is_old);
586 }
587 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
588 // Currently, only attempts to allocate GC alloc regions set
589 // do_expand to true. So, we should only reach here during a
590 // safepoint. If this assumption changes we might have to
591 // reconsider the use of _expand_heap_after_alloc_failure.
592 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
593
594 ergo_verbose1(ErgoHeapSizing,
595 "attempt heap expansion",
596 ergo_format_reason("region allocation request failed")
597 ergo_format_byte("allocation request"),
598 word_size * HeapWordSize);
599 if (expand(word_size * HeapWordSize)) {
600 // Given that expand() succeeded in expanding the heap, and we
601 // always expand the heap by an amount aligned to the heap
602 // region size, the free list should in theory not be empty.
603 // In either case remove_region() will check for NULL.
604 res = _free_list.remove_region(is_old);
605 } else {
606 _expand_heap_after_alloc_failure = false;
607 }
608 }
609 return res;
610 }
611
612 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
613 size_t word_size) {
614 assert(isHumongous(word_size), "word_size should be humongous");
615 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
616
617 uint first = G1_NULL_HRS_INDEX;
618 if (num_regions == 1) {
619 // Only one region to allocate, no need to go through the slower
620 // path. The caller will attempt the expansion if this fails, so
621 // let's not try to expand here too.
622 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
623 if (hr != NULL) {
624 first = hr->hrs_index();
625 } else {
626 first = G1_NULL_HRS_INDEX;
627 }
628 } else {
629 // We can't allocate humongous regions while cleanupComplete() is
630 // running, since some of the regions we find to be empty might not
631 // yet be added to the free list and it is not straightforward to
632 // know which list they are on so that we can remove them. Note
633 // that we only need to do this if we need to allocate more than
634 // one region to satisfy the current humongous allocation
635 // request. If we are only allocating one region we use the common
636 // region allocation code (see above).
637 wait_while_free_regions_coming();
638 append_secondary_free_list_if_not_empty_with_lock();
639
640 if (free_regions() >= num_regions) {
641 first = _hrs.find_contiguous(num_regions);
642 if (first != G1_NULL_HRS_INDEX) {
643 for (uint i = first; i < first + num_regions; ++i) {
644 HeapRegion* hr = region_at(i);
645 assert(hr->is_empty(), "sanity");
646 assert(is_on_master_free_list(hr), "sanity");
647 hr->set_pending_removal(true);
648 }
649 _free_list.remove_all_pending(num_regions);
650 }
651 }
652 }
653 return first;
654 }
655
656 HeapWord*
657 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
658 uint num_regions,
659 size_t word_size) {
660 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
661 assert(isHumongous(word_size), "word_size should be humongous");
662 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
663
664 // Index of last region in the series + 1.
665 uint last = first + num_regions;
666
667 // We need to initialize the region(s) we just discovered. This is
668 // a bit tricky given that it can happen concurrently with
669 // refinement threads refining cards on these regions and
670 // potentially wanting to refine the BOT as they are scanning
671 // those cards (this can happen shortly after a cleanup; see CR
672 // 6991377). So we have to set up the region(s) carefully and in
673 // a specific order.
674
675 // The word size sum of all the regions we will allocate.
676 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
677 assert(word_size <= word_size_sum, "sanity");
678
679 // This will be the "starts humongous" region.
680 HeapRegion* first_hr = region_at(first);
681 // The header of the new object will be placed at the bottom of
682 // the first region.
683 HeapWord* new_obj = first_hr->bottom();
684 // This will be the new end of the first region in the series that
685 // should also match the end of the last region in the series.
686 HeapWord* new_end = new_obj + word_size_sum;
687 // This will be the new top of the first region that will reflect
688 // this allocation.
689 HeapWord* new_top = new_obj + word_size;
690
691 // First, we need to zero the header of the space that we will be
692 // allocating. When we update top further down, some refinement
693 // threads might try to scan the region. By zeroing the header we
694 // ensure that any thread that will try to scan the region will
695 // come across the zero klass word and bail out.
696 //
697 // NOTE: It would not have been correct to have used
698 // CollectedHeap::fill_with_object() and make the space look like
699 // an int array. The thread that is doing the allocation will
700 // later update the object header to a potentially different array
701 // type and, for a very short period of time, the klass and length
702 // fields will be inconsistent. This could cause a refinement
703 // thread to calculate the object size incorrectly.
704 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
705
706 // We will set up the first region as "starts humongous". This
707 // will also update the BOT covering all the regions to reflect
708 // that there is a single object that starts at the bottom of the
709 // first region.
710 first_hr->set_startsHumongous(new_top, new_end);
711
712 // Then, if there are any, we will set up the "continues
713 // humongous" regions.
714 HeapRegion* hr = NULL;
715 for (uint i = first + 1; i < last; ++i) {
716 hr = region_at(i);
717 hr->set_continuesHumongous(first_hr);
718 }
719 // If we have "continues humongous" regions (hr != NULL), then the
720 // end of the last one should match new_end.
721 assert(hr == NULL || hr->end() == new_end, "sanity");
722
723 // Up to this point no concurrent thread would have been able to
724 // do any scanning on any region in this series. All the top
725 // fields still point to bottom, so the intersection between
726 // [bottom,top] and [card_start,card_end] will be empty. Before we
727 // update the top fields, we'll do a storestore to make sure that
728 // no thread sees the update to top before the zeroing of the
729 // object header and the BOT initialization.
730 OrderAccess::storestore();
731
732 // Now that the BOT and the object header have been initialized,
733 // we can update top of the "starts humongous" region.
734 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
735 "new_top should be in this region");
736 first_hr->set_top(new_top);
737 if (_hr_printer.is_active()) {
738 HeapWord* bottom = first_hr->bottom();
739 HeapWord* end = first_hr->orig_end();
740 if ((first + 1) == last) {
741 // the series has a single humongous region
742 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
743 } else {
744 // the series has more than one humongous regions
745 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
746 }
747 }
748
749 // Now, we will update the top fields of the "continues humongous"
750 // regions. The reason we need to do this is that, otherwise,
751 // these regions would look empty and this will confuse parts of
752 // G1. For example, the code that looks for a consecutive number
753 // of empty regions will consider them empty and try to
754 // re-allocate them. We can extend is_empty() to also include
755 // !continuesHumongous(), but it is easier to just update the top
756 // fields here. The way we set top for all regions (i.e., top ==
757 // end for all regions but the last one, top == new_top for the
758 // last one) is actually used when we will free up the humongous
759 // region in free_humongous_region().
760 hr = NULL;
761 for (uint i = first + 1; i < last; ++i) {
762 hr = region_at(i);
763 if ((i + 1) == last) {
764 // last continues humongous region
765 assert(hr->bottom() < new_top && new_top <= hr->end(),
766 "new_top should fall on this region");
767 hr->set_top(new_top);
768 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
769 } else {
770 // not last one
771 assert(new_top > hr->end(), "new_top should be above this region");
772 hr->set_top(hr->end());
773 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
774 }
775 }
776 // If we have continues humongous regions (hr != NULL), then the
777 // end of the last one should match new_end and its top should
778 // match new_top.
779 assert(hr == NULL ||
780 (hr->end() == new_end && hr->top() == new_top), "sanity");
781
782 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
783 _summary_bytes_used += first_hr->used();
784 _humongous_set.add(first_hr);
785
786 return new_obj;
787 }
788
789 // If could fit into free regions w/o expansion, try.
790 // Otherwise, if can expand, do so.
791 // Otherwise, if using ex regions might help, try with ex given back.
792 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
793 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
794
795 verify_region_sets_optional();
796
797 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
798 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
799 uint x_num = expansion_regions();
800 uint fs = _hrs.free_suffix();
801 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
802 if (first == G1_NULL_HRS_INDEX) {
803 // The only thing we can do now is attempt expansion.
804 if (fs + x_num >= num_regions) {
805 // If the number of regions we're trying to allocate for this
806 // object is at most the number of regions in the free suffix,
807 // then the call to humongous_obj_allocate_find_first() above
808 // should have succeeded and we wouldn't be here.
809 //
810 // We should only be trying to expand when the free suffix is
811 // not sufficient for the object _and_ we have some expansion
812 // room available.
813 assert(num_regions > fs, "earlier allocation should have succeeded");
814
815 ergo_verbose1(ErgoHeapSizing,
816 "attempt heap expansion",
817 ergo_format_reason("humongous allocation request failed")
818 ergo_format_byte("allocation request"),
819 word_size * HeapWordSize);
820 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
821 // Even though the heap was expanded, it might not have
822 // reached the desired size. So, we cannot assume that the
823 // allocation will succeed.
824 first = humongous_obj_allocate_find_first(num_regions, word_size);
825 }
826 }
827 }
828
829 HeapWord* result = NULL;
830 if (first != G1_NULL_HRS_INDEX) {
831 result =
832 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
833 assert(result != NULL, "it should always return a valid result");
834
835 // A successful humongous object allocation changes the used space
836 // information of the old generation so we need to recalculate the
837 // sizes and update the jstat counters here.
838 g1mm()->update_sizes();
839 }
840
841 verify_region_sets_optional();
842
843 return result;
844 }
845
846 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
847 assert_heap_not_locked_and_not_at_safepoint();
848 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
849
850 unsigned int dummy_gc_count_before;
851 int dummy_gclocker_retry_count = 0;
852 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
853 }
854
855 HeapWord*
856 G1CollectedHeap::mem_allocate(size_t word_size,
857 bool* gc_overhead_limit_was_exceeded) {
858 assert_heap_not_locked_and_not_at_safepoint();
859
860 // Loop until the allocation is satisfied, or unsatisfied after GC.
861 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
862 unsigned int gc_count_before;
863
864 HeapWord* result = NULL;
865 if (!isHumongous(word_size)) {
866 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
867 } else {
868 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
869 }
870 if (result != NULL) {
871 return result;
872 }
873
874 // Create the garbage collection operation...
875 VM_G1CollectForAllocation op(gc_count_before, word_size);
876 // ...and get the VM thread to execute it.
877 VMThread::execute(&op);
878
879 if (op.prologue_succeeded() && op.pause_succeeded()) {
880 // If the operation was successful we'll return the result even
881 // if it is NULL. If the allocation attempt failed immediately
882 // after a Full GC, it's unlikely we'll be able to allocate now.
883 HeapWord* result = op.result();
884 if (result != NULL && !isHumongous(word_size)) {
885 // Allocations that take place on VM operations do not do any
886 // card dirtying and we have to do it here. We only have to do
887 // this for non-humongous allocations, though.
888 dirty_young_block(result, word_size);
889 }
890 return result;
891 } else {
892 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
893 return NULL;
894 }
895 assert(op.result() == NULL,
896 "the result should be NULL if the VM op did not succeed");
897 }
898
899 // Give a warning if we seem to be looping forever.
900 if ((QueuedAllocationWarningCount > 0) &&
901 (try_count % QueuedAllocationWarningCount == 0)) {
902 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
903 }
904 }
905
906 ShouldNotReachHere();
907 return NULL;
908 }
909
910 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
911 unsigned int *gc_count_before_ret,
912 int* gclocker_retry_count_ret) {
913 // Make sure you read the note in attempt_allocation_humongous().
914
915 assert_heap_not_locked_and_not_at_safepoint();
916 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
917 "be called for humongous allocation requests");
918
919 // We should only get here after the first-level allocation attempt
920 // (attempt_allocation()) failed to allocate.
921
922 // We will loop until a) we manage to successfully perform the
923 // allocation or b) we successfully schedule a collection which
924 // fails to perform the allocation. b) is the only case when we'll
925 // return NULL.
926 HeapWord* result = NULL;
927 for (int try_count = 1; /* we'll return */; try_count += 1) {
928 bool should_try_gc;
929 unsigned int gc_count_before;
930
931 {
932 MutexLockerEx x(Heap_lock);
933
934 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
935 false /* bot_updates */);
936 if (result != NULL) {
937 return result;
938 }
939
940 // If we reach here, attempt_allocation_locked() above failed to
941 // allocate a new region. So the mutator alloc region should be NULL.
942 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
943
944 if (GC_locker::is_active_and_needs_gc()) {
945 if (g1_policy()->can_expand_young_list()) {
946 // No need for an ergo verbose message here,
947 // can_expand_young_list() does this when it returns true.
948 result = _mutator_alloc_region.attempt_allocation_force(word_size,
949 false /* bot_updates */);
950 if (result != NULL) {
951 return result;
952 }
953 }
954 should_try_gc = false;
955 } else {
956 // The GCLocker may not be active but the GCLocker initiated
957 // GC may not yet have been performed (GCLocker::needs_gc()
958 // returns true). In this case we do not try this GC and
959 // wait until the GCLocker initiated GC is performed, and
960 // then retry the allocation.
961 if (GC_locker::needs_gc()) {
962 should_try_gc = false;
963 } else {
964 // Read the GC count while still holding the Heap_lock.
965 gc_count_before = total_collections();
966 should_try_gc = true;
967 }
968 }
969 }
970
971 if (should_try_gc) {
972 bool succeeded;
973 result = do_collection_pause(word_size, gc_count_before, &succeeded,
974 GCCause::_g1_inc_collection_pause);
975 if (result != NULL) {
976 assert(succeeded, "only way to get back a non-NULL result");
977 return result;
978 }
979
980 if (succeeded) {
981 // If we get here we successfully scheduled a collection which
982 // failed to allocate. No point in trying to allocate
983 // further. We'll just return NULL.
984 MutexLockerEx x(Heap_lock);
985 *gc_count_before_ret = total_collections();
986 return NULL;
987 }
988 } else {
989 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
990 MutexLockerEx x(Heap_lock);
991 *gc_count_before_ret = total_collections();
992 return NULL;
993 }
994 // The GCLocker is either active or the GCLocker initiated
995 // GC has not yet been performed. Stall until it is and
996 // then retry the allocation.
997 GC_locker::stall_until_clear();
998 (*gclocker_retry_count_ret) += 1;
999 }
1000
1001 // We can reach here if we were unsuccessful in scheduling a
1002 // collection (because another thread beat us to it) or if we were
1003 // stalled due to the GC locker. In either can we should retry the
1004 // allocation attempt in case another thread successfully
1005 // performed a collection and reclaimed enough space. We do the
1006 // first attempt (without holding the Heap_lock) here and the
1007 // follow-on attempt will be at the start of the next loop
1008 // iteration (after taking the Heap_lock).
1009 result = _mutator_alloc_region.attempt_allocation(word_size,
1010 false /* bot_updates */);
1011 if (result != NULL) {
1012 return result;
1013 }
1014
1015 // Give a warning if we seem to be looping forever.
1016 if ((QueuedAllocationWarningCount > 0) &&
1017 (try_count % QueuedAllocationWarningCount == 0)) {
1018 warning("G1CollectedHeap::attempt_allocation_slow() "
1019 "retries %d times", try_count);
1020 }
1021 }
1022
1023 ShouldNotReachHere();
1024 return NULL;
1025 }
1026
1027 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1028 unsigned int * gc_count_before_ret,
1029 int* gclocker_retry_count_ret) {
1030 // The structure of this method has a lot of similarities to
1031 // attempt_allocation_slow(). The reason these two were not merged
1032 // into a single one is that such a method would require several "if
1033 // allocation is not humongous do this, otherwise do that"
1034 // conditional paths which would obscure its flow. In fact, an early
1035 // version of this code did use a unified method which was harder to
1036 // follow and, as a result, it had subtle bugs that were hard to
1037 // track down. So keeping these two methods separate allows each to
1038 // be more readable. It will be good to keep these two in sync as
1039 // much as possible.
1040
1041 assert_heap_not_locked_and_not_at_safepoint();
1042 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1043 "should only be called for humongous allocations");
1044
1045 // Humongous objects can exhaust the heap quickly, so we should check if we
1046 // need to start a marking cycle at each humongous object allocation. We do
1047 // the check before we do the actual allocation. The reason for doing it
1048 // before the allocation is that we avoid having to keep track of the newly
1049 // allocated memory while we do a GC.
1050 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1051 word_size)) {
1052 collect(GCCause::_g1_humongous_allocation);
1053 }
1054
1055 // We will loop until a) we manage to successfully perform the
1056 // allocation or b) we successfully schedule a collection which
1057 // fails to perform the allocation. b) is the only case when we'll
1058 // return NULL.
1059 HeapWord* result = NULL;
1060 for (int try_count = 1; /* we'll return */; try_count += 1) {
1061 bool should_try_gc;
1062 unsigned int gc_count_before;
1063
1064 {
1065 MutexLockerEx x(Heap_lock);
1066
1067 // Given that humongous objects are not allocated in young
1068 // regions, we'll first try to do the allocation without doing a
1069 // collection hoping that there's enough space in the heap.
1070 result = humongous_obj_allocate(word_size);
1071 if (result != NULL) {
1072 return result;
1073 }
1074
1075 if (GC_locker::is_active_and_needs_gc()) {
1076 should_try_gc = false;
1077 } else {
1078 // The GCLocker may not be active but the GCLocker initiated
1079 // GC may not yet have been performed (GCLocker::needs_gc()
1080 // returns true). In this case we do not try this GC and
1081 // wait until the GCLocker initiated GC is performed, and
1082 // then retry the allocation.
1083 if (GC_locker::needs_gc()) {
1084 should_try_gc = false;
1085 } else {
1086 // Read the GC count while still holding the Heap_lock.
1087 gc_count_before = total_collections();
1088 should_try_gc = true;
1089 }
1090 }
1091 }
1092
1093 if (should_try_gc) {
1094 // If we failed to allocate the humongous object, we should try to
1095 // do a collection pause (if we're allowed) in case it reclaims
1096 // enough space for the allocation to succeed after the pause.
1097
1098 bool succeeded;
1099 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1100 GCCause::_g1_humongous_allocation);
1101 if (result != NULL) {
1102 assert(succeeded, "only way to get back a non-NULL result");
1103 return result;
1104 }
1105
1106 if (succeeded) {
1107 // If we get here we successfully scheduled a collection which
1108 // failed to allocate. No point in trying to allocate
1109 // further. We'll just return NULL.
1110 MutexLockerEx x(Heap_lock);
1111 *gc_count_before_ret = total_collections();
1112 return NULL;
1113 }
1114 } else {
1115 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1116 MutexLockerEx x(Heap_lock);
1117 *gc_count_before_ret = total_collections();
1118 return NULL;
1119 }
1120 // The GCLocker is either active or the GCLocker initiated
1121 // GC has not yet been performed. Stall until it is and
1122 // then retry the allocation.
1123 GC_locker::stall_until_clear();
1124 (*gclocker_retry_count_ret) += 1;
1125 }
1126
1127 // We can reach here if we were unsuccessful in scheduling a
1128 // collection (because another thread beat us to it) or if we were
1129 // stalled due to the GC locker. In either can we should retry the
1130 // allocation attempt in case another thread successfully
1131 // performed a collection and reclaimed enough space. Give a
1132 // warning if we seem to be looping forever.
1133
1134 if ((QueuedAllocationWarningCount > 0) &&
1135 (try_count % QueuedAllocationWarningCount == 0)) {
1136 warning("G1CollectedHeap::attempt_allocation_humongous() "
1137 "retries %d times", try_count);
1138 }
1139 }
1140
1141 ShouldNotReachHere();
1142 return NULL;
1143 }
1144
1145 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1146 bool expect_null_mutator_alloc_region) {
1147 assert_at_safepoint(true /* should_be_vm_thread */);
1148 assert(_mutator_alloc_region.get() == NULL ||
1149 !expect_null_mutator_alloc_region,
1150 "the current alloc region was unexpectedly found to be non-NULL");
1151
1152 if (!isHumongous(word_size)) {
1153 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1154 false /* bot_updates */);
1155 } else {
1156 HeapWord* result = humongous_obj_allocate(word_size);
1157 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1158 g1_policy()->set_initiate_conc_mark_if_possible();
1159 }
1160 return result;
1161 }
1162
1163 ShouldNotReachHere();
1164 }
1165
1166 class PostMCRemSetClearClosure: public HeapRegionClosure {
1167 G1CollectedHeap* _g1h;
1168 ModRefBarrierSet* _mr_bs;
1169 public:
1170 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1171 _g1h(g1h), _mr_bs(mr_bs) {}
1172
1173 bool doHeapRegion(HeapRegion* r) {
1174 HeapRegionRemSet* hrrs = r->rem_set();
1175
1176 if (r->continuesHumongous()) {
1177 // We'll assert that the strong code root list and RSet is empty
1178 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1179 assert(hrrs->occupied() == 0, "RSet should be empty");
1180 return false;
1181 }
1182
1183 _g1h->reset_gc_time_stamps(r);
1184 hrrs->clear();
1185 // You might think here that we could clear just the cards
1186 // corresponding to the used region. But no: if we leave a dirty card
1187 // in a region we might allocate into, then it would prevent that card
1188 // from being enqueued, and cause it to be missed.
1189 // Re: the performance cost: we shouldn't be doing full GC anyway!
1190 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1191
1192 return false;
1193 }
1194 };
1195
1196 void G1CollectedHeap::clear_rsets_post_compaction() {
1197 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1198 heap_region_iterate(&rs_clear);
1199 }
1200
1201 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1202 G1CollectedHeap* _g1h;
1203 UpdateRSOopClosure _cl;
1204 int _worker_i;
1205 public:
1206 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1207 _cl(g1->g1_rem_set(), worker_i),
1208 _worker_i(worker_i),
1209 _g1h(g1)
1210 { }
1211
1212 bool doHeapRegion(HeapRegion* r) {
1213 if (!r->continuesHumongous()) {
1214 _cl.set_from(r);
1215 r->oop_iterate(&_cl);
1216 }
1217 return false;
1218 }
1219 };
1220
1221 class ParRebuildRSTask: public AbstractGangTask {
1222 G1CollectedHeap* _g1;
1223 public:
1224 ParRebuildRSTask(G1CollectedHeap* g1)
1225 : AbstractGangTask("ParRebuildRSTask"),
1226 _g1(g1)
1227 { }
1228
1229 void work(uint worker_id) {
1230 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1231 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1232 _g1->workers()->active_workers(),
1233 HeapRegion::RebuildRSClaimValue);
1234 }
1235 };
1236
1237 class PostCompactionPrinterClosure: public HeapRegionClosure {
1238 private:
1239 G1HRPrinter* _hr_printer;
1240 public:
1241 bool doHeapRegion(HeapRegion* hr) {
1242 assert(!hr->is_young(), "not expecting to find young regions");
1243 // We only generate output for non-empty regions.
1244 if (!hr->is_empty()) {
1245 if (!hr->isHumongous()) {
1246 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1247 } else if (hr->startsHumongous()) {
1248 if (hr->region_num() == 1) {
1249 // single humongous region
1250 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1251 } else {
1252 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1253 }
1254 } else {
1255 assert(hr->continuesHumongous(), "only way to get here");
1256 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1257 }
1258 }
1259 return false;
1260 }
1261
1262 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1263 : _hr_printer(hr_printer) { }
1264 };
1265
1266 void G1CollectedHeap::print_hrs_post_compaction() {
1267 PostCompactionPrinterClosure cl(hr_printer());
1268 heap_region_iterate(&cl);
1269 }
1270
1271 bool G1CollectedHeap::do_collection(bool explicit_gc,
1272 bool clear_all_soft_refs,
1273 size_t word_size) {
1274 assert_at_safepoint(true /* should_be_vm_thread */);
1275
1276 if (GC_locker::check_active_before_gc()) {
1277 return false;
1278 }
1279
1280 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1281 gc_timer->register_gc_start();
1282
1283 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1284 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1285
1286 SvcGCMarker sgcm(SvcGCMarker::FULL);
1287 ResourceMark rm;
1288
1289 print_heap_before_gc();
1290 trace_heap_before_gc(gc_tracer);
1291
1292 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1293
1294 verify_region_sets_optional();
1295
1296 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1297 collector_policy()->should_clear_all_soft_refs();
1298
1299 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1300
1301 {
1302 IsGCActiveMark x;
1303
1304 // Timing
1305 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1306 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1307 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1308
1309 {
1310 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1311 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1312 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1313
1314 double start = os::elapsedTime();
1315 g1_policy()->record_full_collection_start();
1316
1317 // Note: When we have a more flexible GC logging framework that
1318 // allows us to add optional attributes to a GC log record we
1319 // could consider timing and reporting how long we wait in the
1320 // following two methods.
1321 wait_while_free_regions_coming();
1322 // If we start the compaction before the CM threads finish
1323 // scanning the root regions we might trip them over as we'll
1324 // be moving objects / updating references. So let's wait until
1325 // they are done. By telling them to abort, they should complete
1326 // early.
1327 _cm->root_regions()->abort();
1328 _cm->root_regions()->wait_until_scan_finished();
1329 append_secondary_free_list_if_not_empty_with_lock();
1330
1331 gc_prologue(true);
1332 increment_total_collections(true /* full gc */);
1333 increment_old_marking_cycles_started();
1334
1335 assert(used() == recalculate_used(), "Should be equal");
1336
1337 verify_before_gc();
1338
1339 pre_full_gc_dump(gc_timer);
1340
1341 COMPILER2_PRESENT(DerivedPointerTable::clear());
1342
1343 // Disable discovery and empty the discovered lists
1344 // for the CM ref processor.
1345 ref_processor_cm()->disable_discovery();
1346 ref_processor_cm()->abandon_partial_discovery();
1347 ref_processor_cm()->verify_no_references_recorded();
1348
1349 // Abandon current iterations of concurrent marking and concurrent
1350 // refinement, if any are in progress. We have to do this before
1351 // wait_until_scan_finished() below.
1352 concurrent_mark()->abort();
1353
1354 // Make sure we'll choose a new allocation region afterwards.
1355 release_mutator_alloc_region();
1356 abandon_gc_alloc_regions();
1357 g1_rem_set()->cleanupHRRS();
1358
1359 // We should call this after we retire any currently active alloc
1360 // regions so that all the ALLOC / RETIRE events are generated
1361 // before the start GC event.
1362 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1363
1364 // We may have added regions to the current incremental collection
1365 // set between the last GC or pause and now. We need to clear the
1366 // incremental collection set and then start rebuilding it afresh
1367 // after this full GC.
1368 abandon_collection_set(g1_policy()->inc_cset_head());
1369 g1_policy()->clear_incremental_cset();
1370 g1_policy()->stop_incremental_cset_building();
1371
1372 tear_down_region_sets(false /* free_list_only */);
1373 g1_policy()->set_gcs_are_young(true);
1374
1375 // See the comments in g1CollectedHeap.hpp and
1376 // G1CollectedHeap::ref_processing_init() about
1377 // how reference processing currently works in G1.
1378
1379 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1380 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1381
1382 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1383 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1384
1385 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1386 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1387
1388 // Do collection work
1389 {
1390 HandleMark hm; // Discard invalid handles created during gc
1391 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1392 }
1393
1394 assert(free_regions() == 0, "we should not have added any free regions");
1395 rebuild_region_sets(false /* free_list_only */);
1396
1397 // Enqueue any discovered reference objects that have
1398 // not been removed from the discovered lists.
1399 ref_processor_stw()->enqueue_discovered_references();
1400
1401 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1402
1403 MemoryService::track_memory_usage();
1404
1405 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1406 ref_processor_stw()->verify_no_references_recorded();
1407
1408 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1409 ClassLoaderDataGraph::purge();
1410 MetaspaceAux::verify_metrics();
1411
1412 // Note: since we've just done a full GC, concurrent
1413 // marking is no longer active. Therefore we need not
1414 // re-enable reference discovery for the CM ref processor.
1415 // That will be done at the start of the next marking cycle.
1416 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1417 ref_processor_cm()->verify_no_references_recorded();
1418
1419 reset_gc_time_stamp();
1420 // Since everything potentially moved, we will clear all remembered
1421 // sets, and clear all cards. Later we will rebuild remembered
1422 // sets. We will also reset the GC time stamps of the regions.
1423 clear_rsets_post_compaction();
1424 check_gc_time_stamps();
1425
1426 // Resize the heap if necessary.
1427 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1428
1429 if (_hr_printer.is_active()) {
1430 // We should do this after we potentially resize the heap so
1431 // that all the COMMIT / UNCOMMIT events are generated before
1432 // the end GC event.
1433
1434 print_hrs_post_compaction();
1435 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1436 }
1437
1438 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1439 if (hot_card_cache->use_cache()) {
1440 hot_card_cache->reset_card_counts();
1441 hot_card_cache->reset_hot_cache();
1442 }
1443
1444 // Rebuild remembered sets of all regions.
1445 if (G1CollectedHeap::use_parallel_gc_threads()) {
1446 uint n_workers =
1447 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1448 workers()->active_workers(),
1449 Threads::number_of_non_daemon_threads());
1450 assert(UseDynamicNumberOfGCThreads ||
1451 n_workers == workers()->total_workers(),
1452 "If not dynamic should be using all the workers");
1453 workers()->set_active_workers(n_workers);
1454 // Set parallel threads in the heap (_n_par_threads) only
1455 // before a parallel phase and always reset it to 0 after
1456 // the phase so that the number of parallel threads does
1457 // no get carried forward to a serial phase where there
1458 // may be code that is "possibly_parallel".
1459 set_par_threads(n_workers);
1460
1461 ParRebuildRSTask rebuild_rs_task(this);
1462 assert(check_heap_region_claim_values(
1463 HeapRegion::InitialClaimValue), "sanity check");
1464 assert(UseDynamicNumberOfGCThreads ||
1465 workers()->active_workers() == workers()->total_workers(),
1466 "Unless dynamic should use total workers");
1467 // Use the most recent number of active workers
1468 assert(workers()->active_workers() > 0,
1469 "Active workers not properly set");
1470 set_par_threads(workers()->active_workers());
1471 workers()->run_task(&rebuild_rs_task);
1472 set_par_threads(0);
1473 assert(check_heap_region_claim_values(
1474 HeapRegion::RebuildRSClaimValue), "sanity check");
1475 reset_heap_region_claim_values();
1476 } else {
1477 RebuildRSOutOfRegionClosure rebuild_rs(this);
1478 heap_region_iterate(&rebuild_rs);
1479 }
1480
1481 // Rebuild the strong code root lists for each region
1482 rebuild_strong_code_roots();
1483
1484 if (true) { // FIXME
1485 MetaspaceGC::compute_new_size();
1486 }
1487
1488 #ifdef TRACESPINNING
1489 ParallelTaskTerminator::print_termination_counts();
1490 #endif
1491
1492 // Discard all rset updates
1493 JavaThread::dirty_card_queue_set().abandon_logs();
1494 assert(!G1DeferredRSUpdate
1495 || (G1DeferredRSUpdate &&
1496 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1497
1498 _young_list->reset_sampled_info();
1499 // At this point there should be no regions in the
1500 // entire heap tagged as young.
1501 assert(check_young_list_empty(true /* check_heap */),
1502 "young list should be empty at this point");
1503
1504 // Update the number of full collections that have been completed.
1505 increment_old_marking_cycles_completed(false /* concurrent */);
1506
1507 _hrs.verify_optional();
1508 verify_region_sets_optional();
1509
1510 verify_after_gc();
1511
1512 // Start a new incremental collection set for the next pause
1513 assert(g1_policy()->collection_set() == NULL, "must be");
1514 g1_policy()->start_incremental_cset_building();
1515
1516 clear_cset_fast_test();
1517
1518 init_mutator_alloc_region();
1519
1520 double end = os::elapsedTime();
1521 g1_policy()->record_full_collection_end();
1522
1523 if (G1Log::fine()) {
1524 g1_policy()->print_heap_transition();
1525 }
1526
1527 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1528 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1529 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1530 // before any GC notifications are raised.
1531 g1mm()->update_sizes();
1532
1533 gc_epilogue(true);
1534 }
1535
1536 if (G1Log::finer()) {
1537 g1_policy()->print_detailed_heap_transition(true /* full */);
1538 }
1539
1540 print_heap_after_gc();
1541 trace_heap_after_gc(gc_tracer);
1542
1543 post_full_gc_dump(gc_timer);
1544
1545 gc_timer->register_gc_end();
1546 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1547 }
1548
1549 return true;
1550 }
1551
1552 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1553 // do_collection() will return whether it succeeded in performing
1554 // the GC. Currently, there is no facility on the
1555 // do_full_collection() API to notify the caller than the collection
1556 // did not succeed (e.g., because it was locked out by the GC
1557 // locker). So, right now, we'll ignore the return value.
1558 bool dummy = do_collection(true, /* explicit_gc */
1559 clear_all_soft_refs,
1560 0 /* word_size */);
1561 }
1562
1563 // This code is mostly copied from TenuredGeneration.
1564 void
1565 G1CollectedHeap::
1566 resize_if_necessary_after_full_collection(size_t word_size) {
1567 // Include the current allocation, if any, and bytes that will be
1568 // pre-allocated to support collections, as "used".
1569 const size_t used_after_gc = used();
1570 const size_t capacity_after_gc = capacity();
1571 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1572
1573 // This is enforced in arguments.cpp.
1574 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1575 "otherwise the code below doesn't make sense");
1576
1577 // We don't have floating point command-line arguments
1578 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1579 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1580 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1581 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1582
1583 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1584 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1585
1586 // We have to be careful here as these two calculations can overflow
1587 // 32-bit size_t's.
1588 double used_after_gc_d = (double) used_after_gc;
1589 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1590 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1591
1592 // Let's make sure that they are both under the max heap size, which
1593 // by default will make them fit into a size_t.
1594 double desired_capacity_upper_bound = (double) max_heap_size;
1595 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1596 desired_capacity_upper_bound);
1597 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1598 desired_capacity_upper_bound);
1599
1600 // We can now safely turn them into size_t's.
1601 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1602 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1603
1604 // This assert only makes sense here, before we adjust them
1605 // with respect to the min and max heap size.
1606 assert(minimum_desired_capacity <= maximum_desired_capacity,
1607 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1608 "maximum_desired_capacity = "SIZE_FORMAT,
1609 minimum_desired_capacity, maximum_desired_capacity));
1610
1611 // Should not be greater than the heap max size. No need to adjust
1612 // it with respect to the heap min size as it's a lower bound (i.e.,
1613 // we'll try to make the capacity larger than it, not smaller).
1614 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1615 // Should not be less than the heap min size. No need to adjust it
1616 // with respect to the heap max size as it's an upper bound (i.e.,
1617 // we'll try to make the capacity smaller than it, not greater).
1618 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1619
1620 if (capacity_after_gc < minimum_desired_capacity) {
1621 // Don't expand unless it's significant
1622 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1623 ergo_verbose4(ErgoHeapSizing,
1624 "attempt heap expansion",
1625 ergo_format_reason("capacity lower than "
1626 "min desired capacity after Full GC")
1627 ergo_format_byte("capacity")
1628 ergo_format_byte("occupancy")
1629 ergo_format_byte_perc("min desired capacity"),
1630 capacity_after_gc, used_after_gc,
1631 minimum_desired_capacity, (double) MinHeapFreeRatio);
1632 expand(expand_bytes);
1633
1634 // No expansion, now see if we want to shrink
1635 } else if (capacity_after_gc > maximum_desired_capacity) {
1636 // Capacity too large, compute shrinking size
1637 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1638 ergo_verbose4(ErgoHeapSizing,
1639 "attempt heap shrinking",
1640 ergo_format_reason("capacity higher than "
1641 "max desired capacity after Full GC")
1642 ergo_format_byte("capacity")
1643 ergo_format_byte("occupancy")
1644 ergo_format_byte_perc("max desired capacity"),
1645 capacity_after_gc, used_after_gc,
1646 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1647 shrink(shrink_bytes);
1648 }
1649 }
1650
1651
1652 HeapWord*
1653 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1654 bool* succeeded) {
1655 assert_at_safepoint(true /* should_be_vm_thread */);
1656
1657 *succeeded = true;
1658 // Let's attempt the allocation first.
1659 HeapWord* result =
1660 attempt_allocation_at_safepoint(word_size,
1661 false /* expect_null_mutator_alloc_region */);
1662 if (result != NULL) {
1663 assert(*succeeded, "sanity");
1664 return result;
1665 }
1666
1667 // In a G1 heap, we're supposed to keep allocation from failing by
1668 // incremental pauses. Therefore, at least for now, we'll favor
1669 // expansion over collection. (This might change in the future if we can
1670 // do something smarter than full collection to satisfy a failed alloc.)
1671 result = expand_and_allocate(word_size);
1672 if (result != NULL) {
1673 assert(*succeeded, "sanity");
1674 return result;
1675 }
1676
1677 // Expansion didn't work, we'll try to do a Full GC.
1678 bool gc_succeeded = do_collection(false, /* explicit_gc */
1679 false, /* clear_all_soft_refs */
1680 word_size);
1681 if (!gc_succeeded) {
1682 *succeeded = false;
1683 return NULL;
1684 }
1685
1686 // Retry the allocation
1687 result = attempt_allocation_at_safepoint(word_size,
1688 true /* expect_null_mutator_alloc_region */);
1689 if (result != NULL) {
1690 assert(*succeeded, "sanity");
1691 return result;
1692 }
1693
1694 // Then, try a Full GC that will collect all soft references.
1695 gc_succeeded = do_collection(false, /* explicit_gc */
1696 true, /* clear_all_soft_refs */
1697 word_size);
1698 if (!gc_succeeded) {
1699 *succeeded = false;
1700 return NULL;
1701 }
1702
1703 // Retry the allocation once more
1704 result = attempt_allocation_at_safepoint(word_size,
1705 true /* expect_null_mutator_alloc_region */);
1706 if (result != NULL) {
1707 assert(*succeeded, "sanity");
1708 return result;
1709 }
1710
1711 assert(!collector_policy()->should_clear_all_soft_refs(),
1712 "Flag should have been handled and cleared prior to this point");
1713
1714 // What else? We might try synchronous finalization later. If the total
1715 // space available is large enough for the allocation, then a more
1716 // complete compaction phase than we've tried so far might be
1717 // appropriate.
1718 assert(*succeeded, "sanity");
1719 return NULL;
1720 }
1721
1722 // Attempting to expand the heap sufficiently
1723 // to support an allocation of the given "word_size". If
1724 // successful, perform the allocation and return the address of the
1725 // allocated block, or else "NULL".
1726
1727 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1728 assert_at_safepoint(true /* should_be_vm_thread */);
1729
1730 verify_region_sets_optional();
1731
1732 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1733 ergo_verbose1(ErgoHeapSizing,
1734 "attempt heap expansion",
1735 ergo_format_reason("allocation request failed")
1736 ergo_format_byte("allocation request"),
1737 word_size * HeapWordSize);
1738 if (expand(expand_bytes)) {
1739 _hrs.verify_optional();
1740 verify_region_sets_optional();
1741 return attempt_allocation_at_safepoint(word_size,
1742 false /* expect_null_mutator_alloc_region */);
1743 }
1744 return NULL;
1745 }
1746
1747 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1748 HeapWord* new_end) {
1749 assert(old_end != new_end, "don't call this otherwise");
1750 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1751
1752 // Update the committed mem region.
1753 _g1_committed.set_end(new_end);
1754 // Tell the card table about the update.
1755 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1756 // Tell the BOT about the update.
1757 _bot_shared->resize(_g1_committed.word_size());
1758 // Tell the hot card cache about the update
1759 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1760 }
1761
1762 bool G1CollectedHeap::expand(size_t expand_bytes) {
1763 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1764 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1765 HeapRegion::GrainBytes);
1766 ergo_verbose2(ErgoHeapSizing,
1767 "expand the heap",
1768 ergo_format_byte("requested expansion amount")
1769 ergo_format_byte("attempted expansion amount"),
1770 expand_bytes, aligned_expand_bytes);
1771
1772 if (_g1_storage.uncommitted_size() == 0) {
1773 ergo_verbose0(ErgoHeapSizing,
1774 "did not expand the heap",
1775 ergo_format_reason("heap already fully expanded"));
1776 return false;
1777 }
1778
1779 // First commit the memory.
1780 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1781 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1782 if (successful) {
1783 // Then propagate this update to the necessary data structures.
1784 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1785 update_committed_space(old_end, new_end);
1786
1787 FreeRegionList expansion_list("Local Expansion List");
1788 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1789 assert(mr.start() == old_end, "post-condition");
1790 // mr might be a smaller region than what was requested if
1791 // expand_by() was unable to allocate the HeapRegion instances
1792 assert(mr.end() <= new_end, "post-condition");
1793
1794 size_t actual_expand_bytes = mr.byte_size();
1795 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1796 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1797 "post-condition");
1798 if (actual_expand_bytes < aligned_expand_bytes) {
1799 // We could not expand _hrs to the desired size. In this case we
1800 // need to shrink the committed space accordingly.
1801 assert(mr.end() < new_end, "invariant");
1802
1803 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1804 // First uncommit the memory.
1805 _g1_storage.shrink_by(diff_bytes);
1806 // Then propagate this update to the necessary data structures.
1807 update_committed_space(new_end, mr.end());
1808 }
1809 _free_list.add_as_tail(&expansion_list);
1810
1811 if (_hr_printer.is_active()) {
1812 HeapWord* curr = mr.start();
1813 while (curr < mr.end()) {
1814 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1815 _hr_printer.commit(curr, curr_end);
1816 curr = curr_end;
1817 }
1818 assert(curr == mr.end(), "post-condition");
1819 }
1820 g1_policy()->record_new_heap_size(n_regions());
1821 } else {
1822 ergo_verbose0(ErgoHeapSizing,
1823 "did not expand the heap",
1824 ergo_format_reason("heap expansion operation failed"));
1825 // The expansion of the virtual storage space was unsuccessful.
1826 // Let's see if it was because we ran out of swap.
1827 if (G1ExitOnExpansionFailure &&
1828 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1829 // We had head room...
1830 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1831 }
1832 }
1833 return successful;
1834 }
1835
1836 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1837 size_t aligned_shrink_bytes =
1838 ReservedSpace::page_align_size_down(shrink_bytes);
1839 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1840 HeapRegion::GrainBytes);
1841 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1842
1843 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1844 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1845 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1846
1847 ergo_verbose3(ErgoHeapSizing,
1848 "shrink the heap",
1849 ergo_format_byte("requested shrinking amount")
1850 ergo_format_byte("aligned shrinking amount")
1851 ergo_format_byte("attempted shrinking amount"),
1852 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1853 if (num_regions_removed > 0) {
1854 _g1_storage.shrink_by(shrunk_bytes);
1855 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1856
1857 if (_hr_printer.is_active()) {
1858 HeapWord* curr = old_end;
1859 while (curr > new_end) {
1860 HeapWord* curr_end = curr;
1861 curr -= HeapRegion::GrainWords;
1862 _hr_printer.uncommit(curr, curr_end);
1863 }
1864 }
1865
1866 _expansion_regions += num_regions_removed;
1867 update_committed_space(old_end, new_end);
1868 HeapRegionRemSet::shrink_heap(n_regions());
1869 g1_policy()->record_new_heap_size(n_regions());
1870 } else {
1871 ergo_verbose0(ErgoHeapSizing,
1872 "did not shrink the heap",
1873 ergo_format_reason("heap shrinking operation failed"));
1874 }
1875 }
1876
1877 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1878 verify_region_sets_optional();
1879
1880 // We should only reach here at the end of a Full GC which means we
1881 // should not not be holding to any GC alloc regions. The method
1882 // below will make sure of that and do any remaining clean up.
1883 abandon_gc_alloc_regions();
1884
1885 // Instead of tearing down / rebuilding the free lists here, we
1886 // could instead use the remove_all_pending() method on free_list to
1887 // remove only the ones that we need to remove.
1888 tear_down_region_sets(true /* free_list_only */);
1889 shrink_helper(shrink_bytes);
1890 rebuild_region_sets(true /* free_list_only */);
1891
1892 _hrs.verify_optional();
1893 verify_region_sets_optional();
1894 }
1895
1896 // Public methods.
1897
1898 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1899 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1900 #endif // _MSC_VER
1901
1902
1903 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1904 SharedHeap(policy_),
1905 _g1_policy(policy_),
1906 _dirty_card_queue_set(false),
1907 _into_cset_dirty_card_queue_set(false),
1908 _is_alive_closure_cm(this),
1909 _is_alive_closure_stw(this),
1910 _ref_processor_cm(NULL),
1911 _ref_processor_stw(NULL),
1912 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1913 _bot_shared(NULL),
1914 _evac_failure_scan_stack(NULL),
1915 _mark_in_progress(false),
1916 _cg1r(NULL), _summary_bytes_used(0),
1917 _g1mm(NULL),
1918 _refine_cte_cl(NULL),
1919 _full_collection(false),
1920 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1921 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1922 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1923 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1924 _free_regions_coming(false),
1925 _young_list(new YoungList(this)),
1926 _gc_time_stamp(0),
1927 _retained_old_gc_alloc_region(NULL),
1928 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1929 _old_plab_stats(OldPLABSize, PLABWeight),
1930 _expand_heap_after_alloc_failure(true),
1931 _surviving_young_words(NULL),
1932 _old_marking_cycles_started(0),
1933 _old_marking_cycles_completed(0),
1934 _concurrent_cycle_started(false),
1935 _in_cset_fast_test(),
1936 _dirty_cards_region_list(NULL),
1937 _worker_cset_start_region(NULL),
1938 _worker_cset_start_region_time_stamp(NULL),
1939 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1940 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1941 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1942 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1943
1944 _g1h = this;
1945 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1946 vm_exit_during_initialization("Failed necessary allocation.");
1947 }
1948
1949 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1950
1951 int n_queues = MAX2((int)ParallelGCThreads, 1);
1952 _task_queues = new RefToScanQueueSet(n_queues);
1953
1954 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1955 assert(n_rem_sets > 0, "Invariant.");
1956
1957 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1958 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1959 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1960
1961 for (int i = 0; i < n_queues; i++) {
1962 RefToScanQueue* q = new RefToScanQueue();
1963 q->initialize();
1964 _task_queues->register_queue(i, q);
1965 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1966 }
1967 clear_cset_start_regions();
1968
1969 // Initialize the G1EvacuationFailureALot counters and flags.
1970 NOT_PRODUCT(reset_evacuation_should_fail();)
1971
1972 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1973 }
1974
1975 jint G1CollectedHeap::initialize() {
1976 CollectedHeap::pre_initialize();
1977 os::enable_vtime();
1978
1979 G1Log::init();
1980
1981 // Necessary to satisfy locking discipline assertions.
1982
1983 MutexLocker x(Heap_lock);
1984
1985 // We have to initialize the printer before committing the heap, as
1986 // it will be used then.
1987 _hr_printer.set_active(G1PrintHeapRegions);
1988
1989 // While there are no constraints in the GC code that HeapWordSize
1990 // be any particular value, there are multiple other areas in the
1991 // system which believe this to be true (e.g. oop->object_size in some
1992 // cases incorrectly returns the size in wordSize units rather than
1993 // HeapWordSize).
1994 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1995
1996 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1997 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1998 size_t heap_alignment = collector_policy()->heap_alignment();
1999
2000 // Ensure that the sizes are properly aligned.
2001 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2002 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2003 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2004
2005 _cg1r = new ConcurrentG1Refine(this);
2006
2007 // Reserve the maximum.
2008
2009 // When compressed oops are enabled, the preferred heap base
2010 // is calculated by subtracting the requested size from the
2011 // 32Gb boundary and using the result as the base address for
2012 // heap reservation. If the requested size is not aligned to
2013 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2014 // into the ReservedHeapSpace constructor) then the actual
2015 // base of the reserved heap may end up differing from the
2016 // address that was requested (i.e. the preferred heap base).
2017 // If this happens then we could end up using a non-optimal
2018 // compressed oops mode.
2019
2020 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2021 heap_alignment);
2022
2023 // It is important to do this in a way such that concurrent readers can't
2024 // temporarily think something is in the heap. (I've actually seen this
2025 // happen in asserts: DLD.)
2026 _reserved.set_word_size(0);
2027 _reserved.set_start((HeapWord*)heap_rs.base());
2028 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2029
2030 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2031
2032 // Create the gen rem set (and barrier set) for the entire reserved region.
2033 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2034 set_barrier_set(rem_set()->bs());
2035 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2036 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2037 return JNI_ENOMEM;
2038 }
2039
2040 // Also create a G1 rem set.
2041 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2042
2043 // Carve out the G1 part of the heap.
2044
2045 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2046 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2047 g1_rs.size()/HeapWordSize);
2048
2049 _g1_storage.initialize(g1_rs, 0);
2050 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2051 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2052 (HeapWord*) _g1_reserved.end());
2053 assert(_hrs.max_length() == _expansion_regions,
2054 err_msg("max length: %u expansion regions: %u",
2055 _hrs.max_length(), _expansion_regions));
2056
2057 // Do later initialization work for concurrent refinement.
2058 _cg1r->init();
2059
2060 // 6843694 - ensure that the maximum region index can fit
2061 // in the remembered set structures.
2062 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2063 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2064
2065 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2066 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2067 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2068 "too many cards per region");
2069
2070 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2071
2072 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2073 heap_word_size(init_byte_size));
2074
2075 _g1h = this;
2076
2077 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2078
2079 // Create the ConcurrentMark data structure and thread.
2080 // (Must do this late, so that "max_regions" is defined.)
2081 _cm = new ConcurrentMark(this, heap_rs);
2082 if (_cm == NULL || !_cm->completed_initialization()) {
2083 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2084 return JNI_ENOMEM;
2085 }
2086 _cmThread = _cm->cmThread();
2087
2088 // Initialize the from_card cache structure of HeapRegionRemSet.
2089 HeapRegionRemSet::init_heap(max_regions());
2090
2091 // Now expand into the initial heap size.
2092 if (!expand(init_byte_size)) {
2093 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2094 return JNI_ENOMEM;
2095 }
2096
2097 // Perform any initialization actions delegated to the policy.
2098 g1_policy()->init();
2099
2100 _refine_cte_cl =
2101 new RefineCardTableEntryClosure(g1_rem_set(),
2102 concurrent_g1_refine());
2103 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2104
2105 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2106 SATB_Q_FL_lock,
2107 G1SATBProcessCompletedThreshold,
2108 Shared_SATB_Q_lock);
2109
2110 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2111 DirtyCardQ_FL_lock,
2112 concurrent_g1_refine()->yellow_zone(),
2113 concurrent_g1_refine()->red_zone(),
2114 Shared_DirtyCardQ_lock);
2115
2116 if (G1DeferredRSUpdate) {
2117 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2118 DirtyCardQ_FL_lock,
2119 -1, // never trigger processing
2120 -1, // no limit on length
2121 Shared_DirtyCardQ_lock,
2122 &JavaThread::dirty_card_queue_set());
2123 }
2124
2125 // Initialize the card queue set used to hold cards containing
2126 // references into the collection set.
2127 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2128 DirtyCardQ_FL_lock,
2129 -1, // never trigger processing
2130 -1, // no limit on length
2131 Shared_DirtyCardQ_lock,
2132 &JavaThread::dirty_card_queue_set());
2133
2134 // In case we're keeping closure specialization stats, initialize those
2135 // counts and that mechanism.
2136 SpecializationStats::clear();
2137
2138 // Here we allocate the dummy full region that is required by the
2139 // G1AllocRegion class. If we don't pass an address in the reserved
2140 // space here, lots of asserts fire.
2141
2142 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2143 _g1_reserved.start());
2144 // We'll re-use the same region whether the alloc region will
2145 // require BOT updates or not and, if it doesn't, then a non-young
2146 // region will complain that it cannot support allocations without
2147 // BOT updates. So we'll tag the dummy region as young to avoid that.
2148 dummy_region->set_young();
2149 // Make sure it's full.
2150 dummy_region->set_top(dummy_region->end());
2151 G1AllocRegion::setup(this, dummy_region);
2152
2153 init_mutator_alloc_region();
2154
2155 // Do create of the monitoring and management support so that
2156 // values in the heap have been properly initialized.
2157 _g1mm = new G1MonitoringSupport(this);
2158
2159 G1StringDedup::initialize();
2160
2161 return JNI_OK;
2162 }
2163
2164 void G1CollectedHeap::stop() {
2165 // Abort any ongoing concurrent root region scanning and stop all
2166 // concurrent threads. We do this to make sure these threads do
2167 // not continue to execute and access resources (e.g. gclog_or_tty)
2168 // that are destroyed during shutdown.
2169 _cm->root_regions()->abort();
2170 _cm->root_regions()->wait_until_scan_finished();
2171 stop_conc_gc_threads();
2172 }
2173
2174 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2175 return HeapRegion::max_region_size();
2176 }
2177
2178 void G1CollectedHeap::ref_processing_init() {
2179 // Reference processing in G1 currently works as follows:
2180 //
2181 // * There are two reference processor instances. One is
2182 // used to record and process discovered references
2183 // during concurrent marking; the other is used to
2184 // record and process references during STW pauses
2185 // (both full and incremental).
2186 // * Both ref processors need to 'span' the entire heap as
2187 // the regions in the collection set may be dotted around.
2188 //
2189 // * For the concurrent marking ref processor:
2190 // * Reference discovery is enabled at initial marking.
2191 // * Reference discovery is disabled and the discovered
2192 // references processed etc during remarking.
2193 // * Reference discovery is MT (see below).
2194 // * Reference discovery requires a barrier (see below).
2195 // * Reference processing may or may not be MT
2196 // (depending on the value of ParallelRefProcEnabled
2197 // and ParallelGCThreads).
2198 // * A full GC disables reference discovery by the CM
2199 // ref processor and abandons any entries on it's
2200 // discovered lists.
2201 //
2202 // * For the STW processor:
2203 // * Non MT discovery is enabled at the start of a full GC.
2204 // * Processing and enqueueing during a full GC is non-MT.
2205 // * During a full GC, references are processed after marking.
2206 //
2207 // * Discovery (may or may not be MT) is enabled at the start
2208 // of an incremental evacuation pause.
2209 // * References are processed near the end of a STW evacuation pause.
2210 // * For both types of GC:
2211 // * Discovery is atomic - i.e. not concurrent.
2212 // * Reference discovery will not need a barrier.
2213
2214 SharedHeap::ref_processing_init();
2215 MemRegion mr = reserved_region();
2216
2217 // Concurrent Mark ref processor
2218 _ref_processor_cm =
2219 new ReferenceProcessor(mr, // span
2220 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2221 // mt processing
2222 (int) ParallelGCThreads,
2223 // degree of mt processing
2224 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2225 // mt discovery
2226 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2227 // degree of mt discovery
2228 false,
2229 // Reference discovery is not atomic
2230 &_is_alive_closure_cm,
2231 // is alive closure
2232 // (for efficiency/performance)
2233 true);
2234 // Setting next fields of discovered
2235 // lists requires a barrier.
2236
2237 // STW ref processor
2238 _ref_processor_stw =
2239 new ReferenceProcessor(mr, // span
2240 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2241 // mt processing
2242 MAX2((int)ParallelGCThreads, 1),
2243 // degree of mt processing
2244 (ParallelGCThreads > 1),
2245 // mt discovery
2246 MAX2((int)ParallelGCThreads, 1),
2247 // degree of mt discovery
2248 true,
2249 // Reference discovery is atomic
2250 &_is_alive_closure_stw,
2251 // is alive closure
2252 // (for efficiency/performance)
2253 false);
2254 // Setting next fields of discovered
2255 // lists does not require a barrier.
2256 }
2257
2258 size_t G1CollectedHeap::capacity() const {
2259 return _g1_committed.byte_size();
2260 }
2261
2262 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2263 assert(!hr->continuesHumongous(), "pre-condition");
2264 hr->reset_gc_time_stamp();
2265 if (hr->startsHumongous()) {
2266 uint first_index = hr->hrs_index() + 1;
2267 uint last_index = hr->last_hc_index();
2268 for (uint i = first_index; i < last_index; i += 1) {
2269 HeapRegion* chr = region_at(i);
2270 assert(chr->continuesHumongous(), "sanity");
2271 chr->reset_gc_time_stamp();
2272 }
2273 }
2274 }
2275
2276 #ifndef PRODUCT
2277 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2278 private:
2279 unsigned _gc_time_stamp;
2280 bool _failures;
2281
2282 public:
2283 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2284 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2285
2286 virtual bool doHeapRegion(HeapRegion* hr) {
2287 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2288 if (_gc_time_stamp != region_gc_time_stamp) {
2289 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2290 "expected %d", HR_FORMAT_PARAMS(hr),
2291 region_gc_time_stamp, _gc_time_stamp);
2292 _failures = true;
2293 }
2294 return false;
2295 }
2296
2297 bool failures() { return _failures; }
2298 };
2299
2300 void G1CollectedHeap::check_gc_time_stamps() {
2301 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2302 heap_region_iterate(&cl);
2303 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2304 }
2305 #endif // PRODUCT
2306
2307 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2308 DirtyCardQueue* into_cset_dcq,
2309 bool concurrent,
2310 uint worker_i) {
2311 // Clean cards in the hot card cache
2312 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2313 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2314
2315 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2316 int n_completed_buffers = 0;
2317 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2318 n_completed_buffers++;
2319 }
2320 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2321 dcqs.clear_n_completed_buffers();
2322 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2323 }
2324
2325
2326 // Computes the sum of the storage used by the various regions.
2327
2328 size_t G1CollectedHeap::used() const {
2329 assert(Heap_lock->owner() != NULL,
2330 "Should be owned on this thread's behalf.");
2331 size_t result = _summary_bytes_used;
2332 // Read only once in case it is set to NULL concurrently
2333 HeapRegion* hr = _mutator_alloc_region.get();
2334 if (hr != NULL)
2335 result += hr->used();
2336 return result;
2337 }
2338
2339 size_t G1CollectedHeap::used_unlocked() const {
2340 size_t result = _summary_bytes_used;
2341 return result;
2342 }
2343
2344 class SumUsedClosure: public HeapRegionClosure {
2345 size_t _used;
2346 public:
2347 SumUsedClosure() : _used(0) {}
2348 bool doHeapRegion(HeapRegion* r) {
2349 if (!r->continuesHumongous()) {
2350 _used += r->used();
2351 }
2352 return false;
2353 }
2354 size_t result() { return _used; }
2355 };
2356
2357 size_t G1CollectedHeap::recalculate_used() const {
2358 double recalculate_used_start = os::elapsedTime();
2359
2360 SumUsedClosure blk;
2361 heap_region_iterate(&blk);
2362
2363 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2364 return blk.result();
2365 }
2366
2367 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2368 switch (cause) {
2369 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2370 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2371 case GCCause::_g1_humongous_allocation: return true;
2372 default: return false;
2373 }
2374 }
2375
2376 #ifndef PRODUCT
2377 void G1CollectedHeap::allocate_dummy_regions() {
2378 // Let's fill up most of the region
2379 size_t word_size = HeapRegion::GrainWords - 1024;
2380 // And as a result the region we'll allocate will be humongous.
2381 guarantee(isHumongous(word_size), "sanity");
2382
2383 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2384 // Let's use the existing mechanism for the allocation
2385 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2386 if (dummy_obj != NULL) {
2387 MemRegion mr(dummy_obj, word_size);
2388 CollectedHeap::fill_with_object(mr);
2389 } else {
2390 // If we can't allocate once, we probably cannot allocate
2391 // again. Let's get out of the loop.
2392 break;
2393 }
2394 }
2395 }
2396 #endif // !PRODUCT
2397
2398 void G1CollectedHeap::increment_old_marking_cycles_started() {
2399 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2400 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2401 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2402 _old_marking_cycles_started, _old_marking_cycles_completed));
2403
2404 _old_marking_cycles_started++;
2405 }
2406
2407 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2408 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2409
2410 // We assume that if concurrent == true, then the caller is a
2411 // concurrent thread that was joined the Suspendible Thread
2412 // Set. If there's ever a cheap way to check this, we should add an
2413 // assert here.
2414
2415 // Given that this method is called at the end of a Full GC or of a
2416 // concurrent cycle, and those can be nested (i.e., a Full GC can
2417 // interrupt a concurrent cycle), the number of full collections
2418 // completed should be either one (in the case where there was no
2419 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2420 // behind the number of full collections started.
2421
2422 // This is the case for the inner caller, i.e. a Full GC.
2423 assert(concurrent ||
2424 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2425 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2426 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2427 "is inconsistent with _old_marking_cycles_completed = %u",
2428 _old_marking_cycles_started, _old_marking_cycles_completed));
2429
2430 // This is the case for the outer caller, i.e. the concurrent cycle.
2431 assert(!concurrent ||
2432 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2433 err_msg("for outer caller (concurrent cycle): "
2434 "_old_marking_cycles_started = %u "
2435 "is inconsistent with _old_marking_cycles_completed = %u",
2436 _old_marking_cycles_started, _old_marking_cycles_completed));
2437
2438 _old_marking_cycles_completed += 1;
2439
2440 // We need to clear the "in_progress" flag in the CM thread before
2441 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2442 // is set) so that if a waiter requests another System.gc() it doesn't
2443 // incorrectly see that a marking cycle is still in progress.
2444 if (concurrent) {
2445 _cmThread->clear_in_progress();
2446 }
2447
2448 // This notify_all() will ensure that a thread that called
2449 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2450 // and it's waiting for a full GC to finish will be woken up. It is
2451 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2452 FullGCCount_lock->notify_all();
2453 }
2454
2455 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2456 _concurrent_cycle_started = true;
2457 _gc_timer_cm->register_gc_start(start_time);
2458
2459 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2460 trace_heap_before_gc(_gc_tracer_cm);
2461 }
2462
2463 void G1CollectedHeap::register_concurrent_cycle_end() {
2464 if (_concurrent_cycle_started) {
2465 if (_cm->has_aborted()) {
2466 _gc_tracer_cm->report_concurrent_mode_failure();
2467 }
2468
2469 _gc_timer_cm->register_gc_end();
2470 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2471
2472 _concurrent_cycle_started = false;
2473 }
2474 }
2475
2476 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2477 if (_concurrent_cycle_started) {
2478 trace_heap_after_gc(_gc_tracer_cm);
2479 }
2480 }
2481
2482 G1YCType G1CollectedHeap::yc_type() {
2483 bool is_young = g1_policy()->gcs_are_young();
2484 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2485 bool is_during_mark = mark_in_progress();
2486
2487 if (is_initial_mark) {
2488 return InitialMark;
2489 } else if (is_during_mark) {
2490 return DuringMark;
2491 } else if (is_young) {
2492 return Normal;
2493 } else {
2494 return Mixed;
2495 }
2496 }
2497
2498 void G1CollectedHeap::collect(GCCause::Cause cause) {
2499 assert_heap_not_locked();
2500
2501 unsigned int gc_count_before;
2502 unsigned int old_marking_count_before;
2503 bool retry_gc;
2504
2505 do {
2506 retry_gc = false;
2507
2508 {
2509 MutexLocker ml(Heap_lock);
2510
2511 // Read the GC count while holding the Heap_lock
2512 gc_count_before = total_collections();
2513 old_marking_count_before = _old_marking_cycles_started;
2514 }
2515
2516 if (should_do_concurrent_full_gc(cause)) {
2517 // Schedule an initial-mark evacuation pause that will start a
2518 // concurrent cycle. We're setting word_size to 0 which means that
2519 // we are not requesting a post-GC allocation.
2520 VM_G1IncCollectionPause op(gc_count_before,
2521 0, /* word_size */
2522 true, /* should_initiate_conc_mark */
2523 g1_policy()->max_pause_time_ms(),
2524 cause);
2525
2526 VMThread::execute(&op);
2527 if (!op.pause_succeeded()) {
2528 if (old_marking_count_before == _old_marking_cycles_started) {
2529 retry_gc = op.should_retry_gc();
2530 } else {
2531 // A Full GC happened while we were trying to schedule the
2532 // initial-mark GC. No point in starting a new cycle given
2533 // that the whole heap was collected anyway.
2534 }
2535
2536 if (retry_gc) {
2537 if (GC_locker::is_active_and_needs_gc()) {
2538 GC_locker::stall_until_clear();
2539 }
2540 }
2541 }
2542 } else {
2543 if (cause == GCCause::_gc_locker
2544 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2545
2546 // Schedule a standard evacuation pause. We're setting word_size
2547 // to 0 which means that we are not requesting a post-GC allocation.
2548 VM_G1IncCollectionPause op(gc_count_before,
2549 0, /* word_size */
2550 false, /* should_initiate_conc_mark */
2551 g1_policy()->max_pause_time_ms(),
2552 cause);
2553 VMThread::execute(&op);
2554 } else {
2555 // Schedule a Full GC.
2556 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2557 VMThread::execute(&op);
2558 }
2559 }
2560 } while (retry_gc);
2561 }
2562
2563 bool G1CollectedHeap::is_in(const void* p) const {
2564 if (_g1_committed.contains(p)) {
2565 // Given that we know that p is in the committed space,
2566 // heap_region_containing_raw() should successfully
2567 // return the containing region.
2568 HeapRegion* hr = heap_region_containing_raw(p);
2569 return hr->is_in(p);
2570 } else {
2571 return false;
2572 }
2573 }
2574
2575 // Iteration functions.
2576
2577 // Iterates an OopClosure over all ref-containing fields of objects
2578 // within a HeapRegion.
2579
2580 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2581 MemRegion _mr;
2582 ExtendedOopClosure* _cl;
2583 public:
2584 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2585 : _mr(mr), _cl(cl) {}
2586 bool doHeapRegion(HeapRegion* r) {
2587 if (!r->continuesHumongous()) {
2588 r->oop_iterate(_cl);
2589 }
2590 return false;
2591 }
2592 };
2593
2594 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2595 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2596 heap_region_iterate(&blk);
2597 }
2598
2599 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2600 IterateOopClosureRegionClosure blk(mr, cl);
2601 heap_region_iterate(&blk);
2602 }
2603
2604 // Iterates an ObjectClosure over all objects within a HeapRegion.
2605
2606 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2607 ObjectClosure* _cl;
2608 public:
2609 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2610 bool doHeapRegion(HeapRegion* r) {
2611 if (! r->continuesHumongous()) {
2612 r->object_iterate(_cl);
2613 }
2614 return false;
2615 }
2616 };
2617
2618 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2619 IterateObjectClosureRegionClosure blk(cl);
2620 heap_region_iterate(&blk);
2621 }
2622
2623 // Calls a SpaceClosure on a HeapRegion.
2624
2625 class SpaceClosureRegionClosure: public HeapRegionClosure {
2626 SpaceClosure* _cl;
2627 public:
2628 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2629 bool doHeapRegion(HeapRegion* r) {
2630 _cl->do_space(r);
2631 return false;
2632 }
2633 };
2634
2635 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2636 SpaceClosureRegionClosure blk(cl);
2637 heap_region_iterate(&blk);
2638 }
2639
2640 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2641 _hrs.iterate(cl);
2642 }
2643
2644 void
2645 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2646 uint worker_id,
2647 uint no_of_par_workers,
2648 jint claim_value) {
2649 const uint regions = n_regions();
2650 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2651 no_of_par_workers :
2652 1);
2653 assert(UseDynamicNumberOfGCThreads ||
2654 no_of_par_workers == workers()->total_workers(),
2655 "Non dynamic should use fixed number of workers");
2656 // try to spread out the starting points of the workers
2657 const HeapRegion* start_hr =
2658 start_region_for_worker(worker_id, no_of_par_workers);
2659 const uint start_index = start_hr->hrs_index();
2660
2661 // each worker will actually look at all regions
2662 for (uint count = 0; count < regions; ++count) {
2663 const uint index = (start_index + count) % regions;
2664 assert(0 <= index && index < regions, "sanity");
2665 HeapRegion* r = region_at(index);
2666 // we'll ignore "continues humongous" regions (we'll process them
2667 // when we come across their corresponding "start humongous"
2668 // region) and regions already claimed
2669 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2670 continue;
2671 }
2672 // OK, try to claim it
2673 if (r->claimHeapRegion(claim_value)) {
2674 // success!
2675 assert(!r->continuesHumongous(), "sanity");
2676 if (r->startsHumongous()) {
2677 // If the region is "starts humongous" we'll iterate over its
2678 // "continues humongous" first; in fact we'll do them
2679 // first. The order is important. In on case, calling the
2680 // closure on the "starts humongous" region might de-allocate
2681 // and clear all its "continues humongous" regions and, as a
2682 // result, we might end up processing them twice. So, we'll do
2683 // them first (notice: most closures will ignore them anyway) and
2684 // then we'll do the "starts humongous" region.
2685 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2686 HeapRegion* chr = region_at(ch_index);
2687
2688 // if the region has already been claimed or it's not
2689 // "continues humongous" we're done
2690 if (chr->claim_value() == claim_value ||
2691 !chr->continuesHumongous()) {
2692 break;
2693 }
2694
2695 // No one should have claimed it directly. We can given
2696 // that we claimed its "starts humongous" region.
2697 assert(chr->claim_value() != claim_value, "sanity");
2698 assert(chr->humongous_start_region() == r, "sanity");
2699
2700 if (chr->claimHeapRegion(claim_value)) {
2701 // we should always be able to claim it; no one else should
2702 // be trying to claim this region
2703
2704 bool res2 = cl->doHeapRegion(chr);
2705 assert(!res2, "Should not abort");
2706
2707 // Right now, this holds (i.e., no closure that actually
2708 // does something with "continues humongous" regions
2709 // clears them). We might have to weaken it in the future,
2710 // but let's leave these two asserts here for extra safety.
2711 assert(chr->continuesHumongous(), "should still be the case");
2712 assert(chr->humongous_start_region() == r, "sanity");
2713 } else {
2714 guarantee(false, "we should not reach here");
2715 }
2716 }
2717 }
2718
2719 assert(!r->continuesHumongous(), "sanity");
2720 bool res = cl->doHeapRegion(r);
2721 assert(!res, "Should not abort");
2722 }
2723 }
2724 }
2725
2726 class ResetClaimValuesClosure: public HeapRegionClosure {
2727 public:
2728 bool doHeapRegion(HeapRegion* r) {
2729 r->set_claim_value(HeapRegion::InitialClaimValue);
2730 return false;
2731 }
2732 };
2733
2734 void G1CollectedHeap::reset_heap_region_claim_values() {
2735 ResetClaimValuesClosure blk;
2736 heap_region_iterate(&blk);
2737 }
2738
2739 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2740 ResetClaimValuesClosure blk;
2741 collection_set_iterate(&blk);
2742 }
2743
2744 #ifdef ASSERT
2745 // This checks whether all regions in the heap have the correct claim
2746 // value. I also piggy-backed on this a check to ensure that the
2747 // humongous_start_region() information on "continues humongous"
2748 // regions is correct.
2749
2750 class CheckClaimValuesClosure : public HeapRegionClosure {
2751 private:
2752 jint _claim_value;
2753 uint _failures;
2754 HeapRegion* _sh_region;
2755
2756 public:
2757 CheckClaimValuesClosure(jint claim_value) :
2758 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2759 bool doHeapRegion(HeapRegion* r) {
2760 if (r->claim_value() != _claim_value) {
2761 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2762 "claim value = %d, should be %d",
2763 HR_FORMAT_PARAMS(r),
2764 r->claim_value(), _claim_value);
2765 ++_failures;
2766 }
2767 if (!r->isHumongous()) {
2768 _sh_region = NULL;
2769 } else if (r->startsHumongous()) {
2770 _sh_region = r;
2771 } else if (r->continuesHumongous()) {
2772 if (r->humongous_start_region() != _sh_region) {
2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2774 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2775 HR_FORMAT_PARAMS(r),
2776 r->humongous_start_region(),
2777 _sh_region);
2778 ++_failures;
2779 }
2780 }
2781 return false;
2782 }
2783 uint failures() { return _failures; }
2784 };
2785
2786 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2787 CheckClaimValuesClosure cl(claim_value);
2788 heap_region_iterate(&cl);
2789 return cl.failures() == 0;
2790 }
2791
2792 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2793 private:
2794 jint _claim_value;
2795 uint _failures;
2796
2797 public:
2798 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2799 _claim_value(claim_value), _failures(0) { }
2800
2801 uint failures() { return _failures; }
2802
2803 bool doHeapRegion(HeapRegion* hr) {
2804 assert(hr->in_collection_set(), "how?");
2805 assert(!hr->isHumongous(), "H-region in CSet");
2806 if (hr->claim_value() != _claim_value) {
2807 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2808 "claim value = %d, should be %d",
2809 HR_FORMAT_PARAMS(hr),
2810 hr->claim_value(), _claim_value);
2811 _failures += 1;
2812 }
2813 return false;
2814 }
2815 };
2816
2817 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2818 CheckClaimValuesInCSetHRClosure cl(claim_value);
2819 collection_set_iterate(&cl);
2820 return cl.failures() == 0;
2821 }
2822 #endif // ASSERT
2823
2824 // Clear the cached CSet starting regions and (more importantly)
2825 // the time stamps. Called when we reset the GC time stamp.
2826 void G1CollectedHeap::clear_cset_start_regions() {
2827 assert(_worker_cset_start_region != NULL, "sanity");
2828 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2829
2830 int n_queues = MAX2((int)ParallelGCThreads, 1);
2831 for (int i = 0; i < n_queues; i++) {
2832 _worker_cset_start_region[i] = NULL;
2833 _worker_cset_start_region_time_stamp[i] = 0;
2834 }
2835 }
2836
2837 // Given the id of a worker, obtain or calculate a suitable
2838 // starting region for iterating over the current collection set.
2839 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2840 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2841
2842 HeapRegion* result = NULL;
2843 unsigned gc_time_stamp = get_gc_time_stamp();
2844
2845 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2846 // Cached starting region for current worker was set
2847 // during the current pause - so it's valid.
2848 // Note: the cached starting heap region may be NULL
2849 // (when the collection set is empty).
2850 result = _worker_cset_start_region[worker_i];
2851 assert(result == NULL || result->in_collection_set(), "sanity");
2852 return result;
2853 }
2854
2855 // The cached entry was not valid so let's calculate
2856 // a suitable starting heap region for this worker.
2857
2858 // We want the parallel threads to start their collection
2859 // set iteration at different collection set regions to
2860 // avoid contention.
2861 // If we have:
2862 // n collection set regions
2863 // p threads
2864 // Then thread t will start at region floor ((t * n) / p)
2865
2866 result = g1_policy()->collection_set();
2867 if (G1CollectedHeap::use_parallel_gc_threads()) {
2868 uint cs_size = g1_policy()->cset_region_length();
2869 uint active_workers = workers()->active_workers();
2870 assert(UseDynamicNumberOfGCThreads ||
2871 active_workers == workers()->total_workers(),
2872 "Unless dynamic should use total workers");
2873
2874 uint end_ind = (cs_size * worker_i) / active_workers;
2875 uint start_ind = 0;
2876
2877 if (worker_i > 0 &&
2878 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2879 // Previous workers starting region is valid
2880 // so let's iterate from there
2881 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2882 result = _worker_cset_start_region[worker_i - 1];
2883 }
2884
2885 for (uint i = start_ind; i < end_ind; i++) {
2886 result = result->next_in_collection_set();
2887 }
2888 }
2889
2890 // Note: the calculated starting heap region may be NULL
2891 // (when the collection set is empty).
2892 assert(result == NULL || result->in_collection_set(), "sanity");
2893 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2894 "should be updated only once per pause");
2895 _worker_cset_start_region[worker_i] = result;
2896 OrderAccess::storestore();
2897 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2898 return result;
2899 }
2900
2901 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2902 uint no_of_par_workers) {
2903 uint worker_num =
2904 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2905 assert(UseDynamicNumberOfGCThreads ||
2906 no_of_par_workers == workers()->total_workers(),
2907 "Non dynamic should use fixed number of workers");
2908 const uint start_index = n_regions() * worker_i / worker_num;
2909 return region_at(start_index);
2910 }
2911
2912 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2913 HeapRegion* r = g1_policy()->collection_set();
2914 while (r != NULL) {
2915 HeapRegion* next = r->next_in_collection_set();
2916 if (cl->doHeapRegion(r)) {
2917 cl->incomplete();
2918 return;
2919 }
2920 r = next;
2921 }
2922 }
2923
2924 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2925 HeapRegionClosure *cl) {
2926 if (r == NULL) {
2927 // The CSet is empty so there's nothing to do.
2928 return;
2929 }
2930
2931 assert(r->in_collection_set(),
2932 "Start region must be a member of the collection set.");
2933 HeapRegion* cur = r;
2934 while (cur != NULL) {
2935 HeapRegion* next = cur->next_in_collection_set();
2936 if (cl->doHeapRegion(cur) && false) {
2937 cl->incomplete();
2938 return;
2939 }
2940 cur = next;
2941 }
2942 cur = g1_policy()->collection_set();
2943 while (cur != r) {
2944 HeapRegion* next = cur->next_in_collection_set();
2945 if (cl->doHeapRegion(cur) && false) {
2946 cl->incomplete();
2947 return;
2948 }
2949 cur = next;
2950 }
2951 }
2952
2953 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2954 return n_regions() > 0 ? region_at(0) : NULL;
2955 }
2956
2957
2958 Space* G1CollectedHeap::space_containing(const void* addr) const {
2959 Space* res = heap_region_containing(addr);
2960 return res;
2961 }
2962
2963 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2964 Space* sp = space_containing(addr);
2965 if (sp != NULL) {
2966 return sp->block_start(addr);
2967 }
2968 return NULL;
2969 }
2970
2971 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2972 Space* sp = space_containing(addr);
2973 assert(sp != NULL, "block_size of address outside of heap");
2974 return sp->block_size(addr);
2975 }
2976
2977 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2978 Space* sp = space_containing(addr);
2979 return sp->block_is_obj(addr);
2980 }
2981
2982 bool G1CollectedHeap::supports_tlab_allocation() const {
2983 return true;
2984 }
2985
2986 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2987 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2988 }
2989
2990 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2991 return young_list()->eden_used_bytes();
2992 }
2993
2994 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2995 // must be smaller than the humongous object limit.
2996 size_t G1CollectedHeap::max_tlab_size() const {
2997 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2998 }
2999
3000 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3001 // Return the remaining space in the cur alloc region, but not less than
3002 // the min TLAB size.
3003
3004 // Also, this value can be at most the humongous object threshold,
3005 // since we can't allow tlabs to grow big enough to accommodate
3006 // humongous objects.
3007
3008 HeapRegion* hr = _mutator_alloc_region.get();
3009 size_t max_tlab = max_tlab_size() * wordSize;
3010 if (hr == NULL) {
3011 return max_tlab;
3012 } else {
3013 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3014 }
3015 }
3016
3017 size_t G1CollectedHeap::max_capacity() const {
3018 return _g1_reserved.byte_size();
3019 }
3020
3021 jlong G1CollectedHeap::millis_since_last_gc() {
3022 // assert(false, "NYI");
3023 return 0;
3024 }
3025
3026 void G1CollectedHeap::prepare_for_verify() {
3027 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3028 ensure_parsability(false);
3029 }
3030 g1_rem_set()->prepare_for_verify();
3031 }
3032
3033 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3034 VerifyOption vo) {
3035 switch (vo) {
3036 case VerifyOption_G1UsePrevMarking:
3037 return hr->obj_allocated_since_prev_marking(obj);
3038 case VerifyOption_G1UseNextMarking:
3039 return hr->obj_allocated_since_next_marking(obj);
3040 case VerifyOption_G1UseMarkWord:
3041 return false;
3042 default:
3043 ShouldNotReachHere();
3044 }
3045 return false; // keep some compilers happy
3046 }
3047
3048 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3049 switch (vo) {
3050 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3051 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3052 case VerifyOption_G1UseMarkWord: return NULL;
3053 default: ShouldNotReachHere();
3054 }
3055 return NULL; // keep some compilers happy
3056 }
3057
3058 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3059 switch (vo) {
3060 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3061 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3062 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3063 default: ShouldNotReachHere();
3064 }
3065 return false; // keep some compilers happy
3066 }
3067
3068 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3069 switch (vo) {
3070 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3071 case VerifyOption_G1UseNextMarking: return "NTAMS";
3072 case VerifyOption_G1UseMarkWord: return "NONE";
3073 default: ShouldNotReachHere();
3074 }
3075 return NULL; // keep some compilers happy
3076 }
3077
3078 class VerifyRootsClosure: public OopClosure {
3079 private:
3080 G1CollectedHeap* _g1h;
3081 VerifyOption _vo;
3082 bool _failures;
3083 public:
3084 // _vo == UsePrevMarking -> use "prev" marking information,
3085 // _vo == UseNextMarking -> use "next" marking information,
3086 // _vo == UseMarkWord -> use mark word from object header.
3087 VerifyRootsClosure(VerifyOption vo) :
3088 _g1h(G1CollectedHeap::heap()),
3089 _vo(vo),
3090 _failures(false) { }
3091
3092 bool failures() { return _failures; }
3093
3094 template <class T> void do_oop_nv(T* p) {
3095 T heap_oop = oopDesc::load_heap_oop(p);
3096 if (!oopDesc::is_null(heap_oop)) {
3097 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3098 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3099 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3100 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3101 if (_vo == VerifyOption_G1UseMarkWord) {
3102 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3103 }
3104 obj->print_on(gclog_or_tty);
3105 _failures = true;
3106 }
3107 }
3108 }
3109
3110 void do_oop(oop* p) { do_oop_nv(p); }
3111 void do_oop(narrowOop* p) { do_oop_nv(p); }
3112 };
3113
3114 class G1VerifyCodeRootOopClosure: public OopClosure {
3115 G1CollectedHeap* _g1h;
3116 OopClosure* _root_cl;
3117 nmethod* _nm;
3118 VerifyOption _vo;
3119 bool _failures;
3120
3121 template <class T> void do_oop_work(T* p) {
3122 // First verify that this root is live
3123 _root_cl->do_oop(p);
3124
3125 if (!G1VerifyHeapRegionCodeRoots) {
3126 // We're not verifying the code roots attached to heap region.
3127 return;
3128 }
3129
3130 // Don't check the code roots during marking verification in a full GC
3131 if (_vo == VerifyOption_G1UseMarkWord) {
3132 return;
3133 }
3134
3135 // Now verify that the current nmethod (which contains p) is
3136 // in the code root list of the heap region containing the
3137 // object referenced by p.
3138
3139 T heap_oop = oopDesc::load_heap_oop(p);
3140 if (!oopDesc::is_null(heap_oop)) {
3141 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3142
3143 // Now fetch the region containing the object
3144 HeapRegion* hr = _g1h->heap_region_containing(obj);
3145 HeapRegionRemSet* hrrs = hr->rem_set();
3146 // Verify that the strong code root list for this region
3147 // contains the nmethod
3148 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3149 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3150 "from nmethod "PTR_FORMAT" not in strong "
3151 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3152 p, _nm, hr->bottom(), hr->end());
3153 _failures = true;
3154 }
3155 }
3156 }
3157
3158 public:
3159 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3160 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3161
3162 void do_oop(oop* p) { do_oop_work(p); }
3163 void do_oop(narrowOop* p) { do_oop_work(p); }
3164
3165 void set_nmethod(nmethod* nm) { _nm = nm; }
3166 bool failures() { return _failures; }
3167 };
3168
3169 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3170 G1VerifyCodeRootOopClosure* _oop_cl;
3171
3172 public:
3173 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3174 _oop_cl(oop_cl) {}
3175
3176 void do_code_blob(CodeBlob* cb) {
3177 nmethod* nm = cb->as_nmethod_or_null();
3178 if (nm != NULL) {
3179 _oop_cl->set_nmethod(nm);
3180 nm->oops_do(_oop_cl);
3181 }
3182 }
3183 };
3184
3185 class YoungRefCounterClosure : public OopClosure {
3186 G1CollectedHeap* _g1h;
3187 int _count;
3188 public:
3189 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3190 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3191 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3192
3193 int count() { return _count; }
3194 void reset_count() { _count = 0; };
3195 };
3196
3197 class VerifyKlassClosure: public KlassClosure {
3198 YoungRefCounterClosure _young_ref_counter_closure;
3199 OopClosure *_oop_closure;
3200 public:
3201 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3202 void do_klass(Klass* k) {
3203 k->oops_do(_oop_closure);
3204
3205 _young_ref_counter_closure.reset_count();
3206 k->oops_do(&_young_ref_counter_closure);
3207 if (_young_ref_counter_closure.count() > 0) {
3208 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3209 }
3210 }
3211 };
3212
3213 class VerifyLivenessOopClosure: public OopClosure {
3214 G1CollectedHeap* _g1h;
3215 VerifyOption _vo;
3216 public:
3217 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3218 _g1h(g1h), _vo(vo)
3219 { }
3220 void do_oop(narrowOop *p) { do_oop_work(p); }
3221 void do_oop( oop *p) { do_oop_work(p); }
3222
3223 template <class T> void do_oop_work(T *p) {
3224 oop obj = oopDesc::load_decode_heap_oop(p);
3225 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3226 "Dead object referenced by a not dead object");
3227 }
3228 };
3229
3230 class VerifyObjsInRegionClosure: public ObjectClosure {
3231 private:
3232 G1CollectedHeap* _g1h;
3233 size_t _live_bytes;
3234 HeapRegion *_hr;
3235 VerifyOption _vo;
3236 public:
3237 // _vo == UsePrevMarking -> use "prev" marking information,
3238 // _vo == UseNextMarking -> use "next" marking information,
3239 // _vo == UseMarkWord -> use mark word from object header.
3240 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3241 : _live_bytes(0), _hr(hr), _vo(vo) {
3242 _g1h = G1CollectedHeap::heap();
3243 }
3244 void do_object(oop o) {
3245 VerifyLivenessOopClosure isLive(_g1h, _vo);
3246 assert(o != NULL, "Huh?");
3247 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3248 // If the object is alive according to the mark word,
3249 // then verify that the marking information agrees.
3250 // Note we can't verify the contra-positive of the
3251 // above: if the object is dead (according to the mark
3252 // word), it may not be marked, or may have been marked
3253 // but has since became dead, or may have been allocated
3254 // since the last marking.
3255 if (_vo == VerifyOption_G1UseMarkWord) {
3256 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3257 }
3258
3259 o->oop_iterate_no_header(&isLive);
3260 if (!_hr->obj_allocated_since_prev_marking(o)) {
3261 size_t obj_size = o->size(); // Make sure we don't overflow
3262 _live_bytes += (obj_size * HeapWordSize);
3263 }
3264 }
3265 }
3266 size_t live_bytes() { return _live_bytes; }
3267 };
3268
3269 class PrintObjsInRegionClosure : public ObjectClosure {
3270 HeapRegion *_hr;
3271 G1CollectedHeap *_g1;
3272 public:
3273 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3274 _g1 = G1CollectedHeap::heap();
3275 };
3276
3277 void do_object(oop o) {
3278 if (o != NULL) {
3279 HeapWord *start = (HeapWord *) o;
3280 size_t word_sz = o->size();
3281 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3282 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3283 (void*) o, word_sz,
3284 _g1->isMarkedPrev(o),
3285 _g1->isMarkedNext(o),
3286 _hr->obj_allocated_since_prev_marking(o));
3287 HeapWord *end = start + word_sz;
3288 HeapWord *cur;
3289 int *val;
3290 for (cur = start; cur < end; cur++) {
3291 val = (int *) cur;
3292 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3293 }
3294 }
3295 }
3296 };
3297
3298 class VerifyRegionClosure: public HeapRegionClosure {
3299 private:
3300 bool _par;
3301 VerifyOption _vo;
3302 bool _failures;
3303 public:
3304 // _vo == UsePrevMarking -> use "prev" marking information,
3305 // _vo == UseNextMarking -> use "next" marking information,
3306 // _vo == UseMarkWord -> use mark word from object header.
3307 VerifyRegionClosure(bool par, VerifyOption vo)
3308 : _par(par),
3309 _vo(vo),
3310 _failures(false) {}
3311
3312 bool failures() {
3313 return _failures;
3314 }
3315
3316 bool doHeapRegion(HeapRegion* r) {
3317 if (!r->continuesHumongous()) {
3318 bool failures = false;
3319 r->verify(_vo, &failures);
3320 if (failures) {
3321 _failures = true;
3322 } else {
3323 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3324 r->object_iterate(¬_dead_yet_cl);
3325 if (_vo != VerifyOption_G1UseNextMarking) {
3326 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3327 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3328 "max_live_bytes "SIZE_FORMAT" "
3329 "< calculated "SIZE_FORMAT,
3330 r->bottom(), r->end(),
3331 r->max_live_bytes(),
3332 not_dead_yet_cl.live_bytes());
3333 _failures = true;
3334 }
3335 } else {
3336 // When vo == UseNextMarking we cannot currently do a sanity
3337 // check on the live bytes as the calculation has not been
3338 // finalized yet.
3339 }
3340 }
3341 }
3342 return false; // stop the region iteration if we hit a failure
3343 }
3344 };
3345
3346 // This is the task used for parallel verification of the heap regions
3347
3348 class G1ParVerifyTask: public AbstractGangTask {
3349 private:
3350 G1CollectedHeap* _g1h;
3351 VerifyOption _vo;
3352 bool _failures;
3353
3354 public:
3355 // _vo == UsePrevMarking -> use "prev" marking information,
3356 // _vo == UseNextMarking -> use "next" marking information,
3357 // _vo == UseMarkWord -> use mark word from object header.
3358 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3359 AbstractGangTask("Parallel verify task"),
3360 _g1h(g1h),
3361 _vo(vo),
3362 _failures(false) { }
3363
3364 bool failures() {
3365 return _failures;
3366 }
3367
3368 void work(uint worker_id) {
3369 HandleMark hm;
3370 VerifyRegionClosure blk(true, _vo);
3371 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3372 _g1h->workers()->active_workers(),
3373 HeapRegion::ParVerifyClaimValue);
3374 if (blk.failures()) {
3375 _failures = true;
3376 }
3377 }
3378 };
3379
3380 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3381 if (SafepointSynchronize::is_at_safepoint()) {
3382 assert(Thread::current()->is_VM_thread(),
3383 "Expected to be executed serially by the VM thread at this point");
3384
3385 if (!silent) { gclog_or_tty->print("Roots "); }
3386 VerifyRootsClosure rootsCl(vo);
3387 VerifyKlassClosure klassCl(this, &rootsCl);
3388
3389 // We apply the relevant closures to all the oops in the
3390 // system dictionary, class loader data graph and the string table.
3391 // Don't verify the code cache here, since it's verified below.
3392 const int so = SO_AllClasses | SO_Strings;
3393
3394 // Need cleared claim bits for the strong roots processing
3395 ClassLoaderDataGraph::clear_claimed_marks();
3396
3397 process_strong_roots(true, // activate StrongRootsScope
3398 ScanningOption(so), // roots scanning options
3399 &rootsCl,
3400 &klassCl
3401 );
3402
3403 // Verify the nmethods in the code cache.
3404 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3405 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3406 CodeCache::blobs_do(&blobsCl);
3407
3408 bool failures = rootsCl.failures() || codeRootsCl.failures();
3409
3410 if (vo != VerifyOption_G1UseMarkWord) {
3411 // If we're verifying during a full GC then the region sets
3412 // will have been torn down at the start of the GC. Therefore
3413 // verifying the region sets will fail. So we only verify
3414 // the region sets when not in a full GC.
3415 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3416 verify_region_sets();
3417 }
3418
3419 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3420 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3421 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3422 "sanity check");
3423
3424 G1ParVerifyTask task(this, vo);
3425 assert(UseDynamicNumberOfGCThreads ||
3426 workers()->active_workers() == workers()->total_workers(),
3427 "If not dynamic should be using all the workers");
3428 int n_workers = workers()->active_workers();
3429 set_par_threads(n_workers);
3430 workers()->run_task(&task);
3431 set_par_threads(0);
3432 if (task.failures()) {
3433 failures = true;
3434 }
3435
3436 // Checks that the expected amount of parallel work was done.
3437 // The implication is that n_workers is > 0.
3438 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3439 "sanity check");
3440
3441 reset_heap_region_claim_values();
3442
3443 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3444 "sanity check");
3445 } else {
3446 VerifyRegionClosure blk(false, vo);
3447 heap_region_iterate(&blk);
3448 if (blk.failures()) {
3449 failures = true;
3450 }
3451 }
3452 if (!silent) gclog_or_tty->print("RemSet ");
3453 rem_set()->verify();
3454
3455 if (G1StringDedup::is_enabled()) {
3456 if (!silent) gclog_or_tty->print("StrDedup ");
3457 G1StringDedup::verify();
3458 }
3459
3460 if (failures) {
3461 gclog_or_tty->print_cr("Heap:");
3462 // It helps to have the per-region information in the output to
3463 // help us track down what went wrong. This is why we call
3464 // print_extended_on() instead of print_on().
3465 print_extended_on(gclog_or_tty);
3466 gclog_or_tty->print_cr("");
3467 #ifndef PRODUCT
3468 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3469 concurrent_mark()->print_reachable("at-verification-failure",
3470 vo, false /* all */);
3471 }
3472 #endif
3473 gclog_or_tty->flush();
3474 }
3475 guarantee(!failures, "there should not have been any failures");
3476 } else {
3477 if (!silent) {
3478 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3479 if (G1StringDedup::is_enabled()) {
3480 gclog_or_tty->print(", StrDedup");
3481 }
3482 gclog_or_tty->print(") ");
3483 }
3484 }
3485 }
3486
3487 void G1CollectedHeap::verify(bool silent) {
3488 verify(silent, VerifyOption_G1UsePrevMarking);
3489 }
3490
3491 double G1CollectedHeap::verify(bool guard, const char* msg) {
3492 double verify_time_ms = 0.0;
3493
3494 if (guard && total_collections() >= VerifyGCStartAt) {
3495 double verify_start = os::elapsedTime();
3496 HandleMark hm; // Discard invalid handles created during verification
3497 prepare_for_verify();
3498 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3499 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3500 }
3501
3502 return verify_time_ms;
3503 }
3504
3505 void G1CollectedHeap::verify_before_gc() {
3506 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3507 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3508 }
3509
3510 void G1CollectedHeap::verify_after_gc() {
3511 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3512 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3513 }
3514
3515 class PrintRegionClosure: public HeapRegionClosure {
3516 outputStream* _st;
3517 public:
3518 PrintRegionClosure(outputStream* st) : _st(st) {}
3519 bool doHeapRegion(HeapRegion* r) {
3520 r->print_on(_st);
3521 return false;
3522 }
3523 };
3524
3525 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3526 const HeapRegion* hr,
3527 const VerifyOption vo) const {
3528 switch (vo) {
3529 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3530 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3531 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3532 default: ShouldNotReachHere();
3533 }
3534 return false; // keep some compilers happy
3535 }
3536
3537 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3538 const VerifyOption vo) const {
3539 switch (vo) {
3540 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3541 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3542 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3543 default: ShouldNotReachHere();
3544 }
3545 return false; // keep some compilers happy
3546 }
3547
3548 void G1CollectedHeap::print_on(outputStream* st) const {
3549 st->print(" %-20s", "garbage-first heap");
3550 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3551 capacity()/K, used_unlocked()/K);
3552 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3553 _g1_storage.low_boundary(),
3554 _g1_storage.high(),
3555 _g1_storage.high_boundary());
3556 st->cr();
3557 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3558 uint young_regions = _young_list->length();
3559 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3560 (size_t) young_regions * HeapRegion::GrainBytes / K);
3561 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3562 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3563 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3564 st->cr();
3565 MetaspaceAux::print_on(st);
3566 }
3567
3568 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3569 print_on(st);
3570
3571 // Print the per-region information.
3572 st->cr();
3573 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3574 "HS=humongous(starts), HC=humongous(continues), "
3575 "CS=collection set, F=free, TS=gc time stamp, "
3576 "PTAMS=previous top-at-mark-start, "
3577 "NTAMS=next top-at-mark-start)");
3578 PrintRegionClosure blk(st);
3579 heap_region_iterate(&blk);
3580 }
3581
3582 void G1CollectedHeap::print_on_error(outputStream* st) const {
3583 this->CollectedHeap::print_on_error(st);
3584
3585 if (_cm != NULL) {
3586 st->cr();
3587 _cm->print_on_error(st);
3588 }
3589 }
3590
3591 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3592 if (G1CollectedHeap::use_parallel_gc_threads()) {
3593 workers()->print_worker_threads_on(st);
3594 }
3595 _cmThread->print_on(st);
3596 st->cr();
3597 _cm->print_worker_threads_on(st);
3598 _cg1r->print_worker_threads_on(st);
3599 if (G1StringDedup::is_enabled()) {
3600 G1StringDedup::print_worker_threads_on(st);
3601 }
3602 }
3603
3604 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3605 if (G1CollectedHeap::use_parallel_gc_threads()) {
3606 workers()->threads_do(tc);
3607 }
3608 tc->do_thread(_cmThread);
3609 _cg1r->threads_do(tc);
3610 if (G1StringDedup::is_enabled()) {
3611 G1StringDedup::threads_do(tc);
3612 }
3613 }
3614
3615 void G1CollectedHeap::print_tracing_info() const {
3616 // We'll overload this to mean "trace GC pause statistics."
3617 if (TraceGen0Time || TraceGen1Time) {
3618 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3619 // to that.
3620 g1_policy()->print_tracing_info();
3621 }
3622 if (G1SummarizeRSetStats) {
3623 g1_rem_set()->print_summary_info();
3624 }
3625 if (G1SummarizeConcMark) {
3626 concurrent_mark()->print_summary_info();
3627 }
3628 g1_policy()->print_yg_surv_rate_info();
3629 SpecializationStats::print();
3630 }
3631
3632 #ifndef PRODUCT
3633 // Helpful for debugging RSet issues.
3634
3635 class PrintRSetsClosure : public HeapRegionClosure {
3636 private:
3637 const char* _msg;
3638 size_t _occupied_sum;
3639
3640 public:
3641 bool doHeapRegion(HeapRegion* r) {
3642 HeapRegionRemSet* hrrs = r->rem_set();
3643 size_t occupied = hrrs->occupied();
3644 _occupied_sum += occupied;
3645
3646 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3647 HR_FORMAT_PARAMS(r));
3648 if (occupied == 0) {
3649 gclog_or_tty->print_cr(" RSet is empty");
3650 } else {
3651 hrrs->print();
3652 }
3653 gclog_or_tty->print_cr("----------");
3654 return false;
3655 }
3656
3657 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3658 gclog_or_tty->cr();
3659 gclog_or_tty->print_cr("========================================");
3660 gclog_or_tty->print_cr(msg);
3661 gclog_or_tty->cr();
3662 }
3663
3664 ~PrintRSetsClosure() {
3665 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3666 gclog_or_tty->print_cr("========================================");
3667 gclog_or_tty->cr();
3668 }
3669 };
3670
3671 void G1CollectedHeap::print_cset_rsets() {
3672 PrintRSetsClosure cl("Printing CSet RSets");
3673 collection_set_iterate(&cl);
3674 }
3675
3676 void G1CollectedHeap::print_all_rsets() {
3677 PrintRSetsClosure cl("Printing All RSets");;
3678 heap_region_iterate(&cl);
3679 }
3680 #endif // PRODUCT
3681
3682 G1CollectedHeap* G1CollectedHeap::heap() {
3683 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3684 "not a garbage-first heap");
3685 return _g1h;
3686 }
3687
3688 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3689 // always_do_update_barrier = false;
3690 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3691 // Fill TLAB's and such
3692 accumulate_statistics_all_tlabs();
3693 ensure_parsability(true);
3694
3695 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3696 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3697 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3698 }
3699 }
3700
3701 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3702
3703 if (G1SummarizeRSetStats &&
3704 (G1SummarizeRSetStatsPeriod > 0) &&
3705 // we are at the end of the GC. Total collections has already been increased.
3706 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3707 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3708 }
3709
3710 // FIXME: what is this about?
3711 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3712 // is set.
3713 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3714 "derived pointer present"));
3715 // always_do_update_barrier = true;
3716
3717 resize_all_tlabs();
3718
3719 // We have just completed a GC. Update the soft reference
3720 // policy with the new heap occupancy
3721 Universe::update_heap_info_at_gc();
3722 }
3723
3724 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3725 unsigned int gc_count_before,
3726 bool* succeeded,
3727 GCCause::Cause gc_cause) {
3728 assert_heap_not_locked_and_not_at_safepoint();
3729 g1_policy()->record_stop_world_start();
3730 VM_G1IncCollectionPause op(gc_count_before,
3731 word_size,
3732 false, /* should_initiate_conc_mark */
3733 g1_policy()->max_pause_time_ms(),
3734 gc_cause);
3735 VMThread::execute(&op);
3736
3737 HeapWord* result = op.result();
3738 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3739 assert(result == NULL || ret_succeeded,
3740 "the result should be NULL if the VM did not succeed");
3741 *succeeded = ret_succeeded;
3742
3743 assert_heap_not_locked();
3744 return result;
3745 }
3746
3747 void
3748 G1CollectedHeap::doConcurrentMark() {
3749 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3750 if (!_cmThread->in_progress()) {
3751 _cmThread->set_started();
3752 CGC_lock->notify();
3753 }
3754 }
3755
3756 size_t G1CollectedHeap::pending_card_num() {
3757 size_t extra_cards = 0;
3758 JavaThread *curr = Threads::first();
3759 while (curr != NULL) {
3760 DirtyCardQueue& dcq = curr->dirty_card_queue();
3761 extra_cards += dcq.size();
3762 curr = curr->next();
3763 }
3764 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3765 size_t buffer_size = dcqs.buffer_size();
3766 size_t buffer_num = dcqs.completed_buffers_num();
3767
3768 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3769 // in bytes - not the number of 'entries'. We need to convert
3770 // into a number of cards.
3771 return (buffer_size * buffer_num + extra_cards) / oopSize;
3772 }
3773
3774 size_t G1CollectedHeap::cards_scanned() {
3775 return g1_rem_set()->cardsScanned();
3776 }
3777
3778 void
3779 G1CollectedHeap::setup_surviving_young_words() {
3780 assert(_surviving_young_words == NULL, "pre-condition");
3781 uint array_length = g1_policy()->young_cset_region_length();
3782 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3783 if (_surviving_young_words == NULL) {
3784 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3785 "Not enough space for young surv words summary.");
3786 }
3787 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3788 #ifdef ASSERT
3789 for (uint i = 0; i < array_length; ++i) {
3790 assert( _surviving_young_words[i] == 0, "memset above" );
3791 }
3792 #endif // !ASSERT
3793 }
3794
3795 void
3796 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3797 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3798 uint array_length = g1_policy()->young_cset_region_length();
3799 for (uint i = 0; i < array_length; ++i) {
3800 _surviving_young_words[i] += surv_young_words[i];
3801 }
3802 }
3803
3804 void
3805 G1CollectedHeap::cleanup_surviving_young_words() {
3806 guarantee( _surviving_young_words != NULL, "pre-condition" );
3807 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3808 _surviving_young_words = NULL;
3809 }
3810
3811 #ifdef ASSERT
3812 class VerifyCSetClosure: public HeapRegionClosure {
3813 public:
3814 bool doHeapRegion(HeapRegion* hr) {
3815 // Here we check that the CSet region's RSet is ready for parallel
3816 // iteration. The fields that we'll verify are only manipulated
3817 // when the region is part of a CSet and is collected. Afterwards,
3818 // we reset these fields when we clear the region's RSet (when the
3819 // region is freed) so they are ready when the region is
3820 // re-allocated. The only exception to this is if there's an
3821 // evacuation failure and instead of freeing the region we leave
3822 // it in the heap. In that case, we reset these fields during
3823 // evacuation failure handling.
3824 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3825
3826 // Here's a good place to add any other checks we'd like to
3827 // perform on CSet regions.
3828 return false;
3829 }
3830 };
3831 #endif // ASSERT
3832
3833 #if TASKQUEUE_STATS
3834 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3835 st->print_raw_cr("GC Task Stats");
3836 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3837 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3838 }
3839
3840 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3841 print_taskqueue_stats_hdr(st);
3842
3843 TaskQueueStats totals;
3844 const int n = workers() != NULL ? workers()->total_workers() : 1;
3845 for (int i = 0; i < n; ++i) {
3846 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3847 totals += task_queue(i)->stats;
3848 }
3849 st->print_raw("tot "); totals.print(st); st->cr();
3850
3851 DEBUG_ONLY(totals.verify());
3852 }
3853
3854 void G1CollectedHeap::reset_taskqueue_stats() {
3855 const int n = workers() != NULL ? workers()->total_workers() : 1;
3856 for (int i = 0; i < n; ++i) {
3857 task_queue(i)->stats.reset();
3858 }
3859 }
3860 #endif // TASKQUEUE_STATS
3861
3862 void G1CollectedHeap::log_gc_header() {
3863 if (!G1Log::fine()) {
3864 return;
3865 }
3866
3867 gclog_or_tty->date_stamp(PrintGCDateStamps);
3868 gclog_or_tty->stamp(PrintGCTimeStamps);
3869
3870 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3871 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3872 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3873
3874 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3875 }
3876
3877 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3878 if (!G1Log::fine()) {
3879 return;
3880 }
3881
3882 if (G1Log::finer()) {
3883 if (evacuation_failed()) {
3884 gclog_or_tty->print(" (to-space exhausted)");
3885 }
3886 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3887 g1_policy()->phase_times()->note_gc_end();
3888 g1_policy()->phase_times()->print(pause_time_sec);
3889 g1_policy()->print_detailed_heap_transition();
3890 } else {
3891 if (evacuation_failed()) {
3892 gclog_or_tty->print("--");
3893 }
3894 g1_policy()->print_heap_transition();
3895 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3896 }
3897 gclog_or_tty->flush();
3898 }
3899
3900 bool
3901 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3902 assert_at_safepoint(true /* should_be_vm_thread */);
3903 guarantee(!is_gc_active(), "collection is not reentrant");
3904
3905 if (GC_locker::check_active_before_gc()) {
3906 return false;
3907 }
3908
3909 _gc_timer_stw->register_gc_start();
3910
3911 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3912
3913 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3914 ResourceMark rm;
3915
3916 print_heap_before_gc();
3917 trace_heap_before_gc(_gc_tracer_stw);
3918
3919 verify_region_sets_optional();
3920 verify_dirty_young_regions();
3921
3922 // This call will decide whether this pause is an initial-mark
3923 // pause. If it is, during_initial_mark_pause() will return true
3924 // for the duration of this pause.
3925 g1_policy()->decide_on_conc_mark_initiation();
3926
3927 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3928 assert(!g1_policy()->during_initial_mark_pause() ||
3929 g1_policy()->gcs_are_young(), "sanity");
3930
3931 // We also do not allow mixed GCs during marking.
3932 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3933
3934 // Record whether this pause is an initial mark. When the current
3935 // thread has completed its logging output and it's safe to signal
3936 // the CM thread, the flag's value in the policy has been reset.
3937 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3938
3939 // Inner scope for scope based logging, timers, and stats collection
3940 {
3941 EvacuationInfo evacuation_info;
3942
3943 if (g1_policy()->during_initial_mark_pause()) {
3944 // We are about to start a marking cycle, so we increment the
3945 // full collection counter.
3946 increment_old_marking_cycles_started();
3947 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3948 }
3949
3950 _gc_tracer_stw->report_yc_type(yc_type());
3951
3952 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3953
3954 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3955 workers()->active_workers() : 1);
3956 double pause_start_sec = os::elapsedTime();
3957 g1_policy()->phase_times()->note_gc_start(active_workers);
3958 log_gc_header();
3959
3960 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3961 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3962
3963 // If the secondary_free_list is not empty, append it to the
3964 // free_list. No need to wait for the cleanup operation to finish;
3965 // the region allocation code will check the secondary_free_list
3966 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3967 // set, skip this step so that the region allocation code has to
3968 // get entries from the secondary_free_list.
3969 if (!G1StressConcRegionFreeing) {
3970 append_secondary_free_list_if_not_empty_with_lock();
3971 }
3972
3973 assert(check_young_list_well_formed(), "young list should be well formed");
3974 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3975 "sanity check");
3976
3977 // Don't dynamically change the number of GC threads this early. A value of
3978 // 0 is used to indicate serial work. When parallel work is done,
3979 // it will be set.
3980
3981 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3982 IsGCActiveMark x;
3983
3984 gc_prologue(false);
3985 increment_total_collections(false /* full gc */);
3986 increment_gc_time_stamp();
3987
3988 verify_before_gc();
3989
3990 COMPILER2_PRESENT(DerivedPointerTable::clear());
3991
3992 // Please see comment in g1CollectedHeap.hpp and
3993 // G1CollectedHeap::ref_processing_init() to see how
3994 // reference processing currently works in G1.
3995
3996 // Enable discovery in the STW reference processor
3997 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3998 true /*verify_no_refs*/);
3999
4000 {
4001 // We want to temporarily turn off discovery by the
4002 // CM ref processor, if necessary, and turn it back on
4003 // on again later if we do. Using a scoped
4004 // NoRefDiscovery object will do this.
4005 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4006
4007 // Forget the current alloc region (we might even choose it to be part
4008 // of the collection set!).
4009 release_mutator_alloc_region();
4010
4011 // We should call this after we retire the mutator alloc
4012 // region(s) so that all the ALLOC / RETIRE events are generated
4013 // before the start GC event.
4014 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4015
4016 // This timing is only used by the ergonomics to handle our pause target.
4017 // It is unclear why this should not include the full pause. We will
4018 // investigate this in CR 7178365.
4019 //
4020 // Preserving the old comment here if that helps the investigation:
4021 //
4022 // The elapsed time induced by the start time below deliberately elides
4023 // the possible verification above.
4024 double sample_start_time_sec = os::elapsedTime();
4025
4026 #if YOUNG_LIST_VERBOSE
4027 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4028 _young_list->print();
4029 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4030 #endif // YOUNG_LIST_VERBOSE
4031
4032 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4033
4034 double scan_wait_start = os::elapsedTime();
4035 // We have to wait until the CM threads finish scanning the
4036 // root regions as it's the only way to ensure that all the
4037 // objects on them have been correctly scanned before we start
4038 // moving them during the GC.
4039 bool waited = _cm->root_regions()->wait_until_scan_finished();
4040 double wait_time_ms = 0.0;
4041 if (waited) {
4042 double scan_wait_end = os::elapsedTime();
4043 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4044 }
4045 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4046
4047 #if YOUNG_LIST_VERBOSE
4048 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4049 _young_list->print();
4050 #endif // YOUNG_LIST_VERBOSE
4051
4052 if (g1_policy()->during_initial_mark_pause()) {
4053 concurrent_mark()->checkpointRootsInitialPre();
4054 }
4055
4056 #if YOUNG_LIST_VERBOSE
4057 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4058 _young_list->print();
4059 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4060 #endif // YOUNG_LIST_VERBOSE
4061
4062 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4063
4064 _cm->note_start_of_gc();
4065 // We should not verify the per-thread SATB buffers given that
4066 // we have not filtered them yet (we'll do so during the
4067 // GC). We also call this after finalize_cset() to
4068 // ensure that the CSet has been finalized.
4069 _cm->verify_no_cset_oops(true /* verify_stacks */,
4070 true /* verify_enqueued_buffers */,
4071 false /* verify_thread_buffers */,
4072 true /* verify_fingers */);
4073
4074 if (_hr_printer.is_active()) {
4075 HeapRegion* hr = g1_policy()->collection_set();
4076 while (hr != NULL) {
4077 G1HRPrinter::RegionType type;
4078 if (!hr->is_young()) {
4079 type = G1HRPrinter::Old;
4080 } else if (hr->is_survivor()) {
4081 type = G1HRPrinter::Survivor;
4082 } else {
4083 type = G1HRPrinter::Eden;
4084 }
4085 _hr_printer.cset(hr);
4086 hr = hr->next_in_collection_set();
4087 }
4088 }
4089
4090 #ifdef ASSERT
4091 VerifyCSetClosure cl;
4092 collection_set_iterate(&cl);
4093 #endif // ASSERT
4094
4095 setup_surviving_young_words();
4096
4097 // Initialize the GC alloc regions.
4098 init_gc_alloc_regions(evacuation_info);
4099
4100 // Actually do the work...
4101 evacuate_collection_set(evacuation_info);
4102
4103 // We do this to mainly verify the per-thread SATB buffers
4104 // (which have been filtered by now) since we didn't verify
4105 // them earlier. No point in re-checking the stacks / enqueued
4106 // buffers given that the CSet has not changed since last time
4107 // we checked.
4108 _cm->verify_no_cset_oops(false /* verify_stacks */,
4109 false /* verify_enqueued_buffers */,
4110 true /* verify_thread_buffers */,
4111 true /* verify_fingers */);
4112
4113 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4114 g1_policy()->clear_collection_set();
4115
4116 cleanup_surviving_young_words();
4117
4118 // Start a new incremental collection set for the next pause.
4119 g1_policy()->start_incremental_cset_building();
4120
4121 clear_cset_fast_test();
4122
4123 _young_list->reset_sampled_info();
4124
4125 // Don't check the whole heap at this point as the
4126 // GC alloc regions from this pause have been tagged
4127 // as survivors and moved on to the survivor list.
4128 // Survivor regions will fail the !is_young() check.
4129 assert(check_young_list_empty(false /* check_heap */),
4130 "young list should be empty");
4131
4132 #if YOUNG_LIST_VERBOSE
4133 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4134 _young_list->print();
4135 #endif // YOUNG_LIST_VERBOSE
4136
4137 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4138 _young_list->first_survivor_region(),
4139 _young_list->last_survivor_region());
4140
4141 _young_list->reset_auxilary_lists();
4142
4143 if (evacuation_failed()) {
4144 _summary_bytes_used = recalculate_used();
4145 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4146 for (uint i = 0; i < n_queues; i++) {
4147 if (_evacuation_failed_info_array[i].has_failed()) {
4148 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4149 }
4150 }
4151 } else {
4152 // The "used" of the the collection set have already been subtracted
4153 // when they were freed. Add in the bytes evacuated.
4154 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4155 }
4156
4157 if (g1_policy()->during_initial_mark_pause()) {
4158 // We have to do this before we notify the CM threads that
4159 // they can start working to make sure that all the
4160 // appropriate initialization is done on the CM object.
4161 concurrent_mark()->checkpointRootsInitialPost();
4162 set_marking_started();
4163 // Note that we don't actually trigger the CM thread at
4164 // this point. We do that later when we're sure that
4165 // the current thread has completed its logging output.
4166 }
4167
4168 allocate_dummy_regions();
4169
4170 #if YOUNG_LIST_VERBOSE
4171 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4172 _young_list->print();
4173 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4174 #endif // YOUNG_LIST_VERBOSE
4175
4176 init_mutator_alloc_region();
4177
4178 {
4179 size_t expand_bytes = g1_policy()->expansion_amount();
4180 if (expand_bytes > 0) {
4181 size_t bytes_before = capacity();
4182 // No need for an ergo verbose message here,
4183 // expansion_amount() does this when it returns a value > 0.
4184 if (!expand(expand_bytes)) {
4185 // We failed to expand the heap so let's verify that
4186 // committed/uncommitted amount match the backing store
4187 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4188 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4189 }
4190 }
4191 }
4192
4193 // We redo the verification but now wrt to the new CSet which
4194 // has just got initialized after the previous CSet was freed.
4195 _cm->verify_no_cset_oops(true /* verify_stacks */,
4196 true /* verify_enqueued_buffers */,
4197 true /* verify_thread_buffers */,
4198 true /* verify_fingers */);
4199 _cm->note_end_of_gc();
4200
4201 // This timing is only used by the ergonomics to handle our pause target.
4202 // It is unclear why this should not include the full pause. We will
4203 // investigate this in CR 7178365.
4204 double sample_end_time_sec = os::elapsedTime();
4205 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4206 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4207
4208 MemoryService::track_memory_usage();
4209
4210 // In prepare_for_verify() below we'll need to scan the deferred
4211 // update buffers to bring the RSets up-to-date if
4212 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4213 // the update buffers we'll probably need to scan cards on the
4214 // regions we just allocated to (i.e., the GC alloc
4215 // regions). However, during the last GC we called
4216 // set_saved_mark() on all the GC alloc regions, so card
4217 // scanning might skip the [saved_mark_word()...top()] area of
4218 // those regions (i.e., the area we allocated objects into
4219 // during the last GC). But it shouldn't. Given that
4220 // saved_mark_word() is conditional on whether the GC time stamp
4221 // on the region is current or not, by incrementing the GC time
4222 // stamp here we invalidate all the GC time stamps on all the
4223 // regions and saved_mark_word() will simply return top() for
4224 // all the regions. This is a nicer way of ensuring this rather
4225 // than iterating over the regions and fixing them. In fact, the
4226 // GC time stamp increment here also ensures that
4227 // saved_mark_word() will return top() between pauses, i.e.,
4228 // during concurrent refinement. So we don't need the
4229 // is_gc_active() check to decided which top to use when
4230 // scanning cards (see CR 7039627).
4231 increment_gc_time_stamp();
4232
4233 verify_after_gc();
4234
4235 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4236 ref_processor_stw()->verify_no_references_recorded();
4237
4238 // CM reference discovery will be re-enabled if necessary.
4239 }
4240
4241 // We should do this after we potentially expand the heap so
4242 // that all the COMMIT events are generated before the end GC
4243 // event, and after we retire the GC alloc regions so that all
4244 // RETIRE events are generated before the end GC event.
4245 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4246
4247 if (mark_in_progress()) {
4248 concurrent_mark()->update_g1_committed();
4249 }
4250
4251 #ifdef TRACESPINNING
4252 ParallelTaskTerminator::print_termination_counts();
4253 #endif
4254
4255 gc_epilogue(false);
4256 }
4257
4258 // Print the remainder of the GC log output.
4259 log_gc_footer(os::elapsedTime() - pause_start_sec);
4260
4261 // It is not yet to safe to tell the concurrent mark to
4262 // start as we have some optional output below. We don't want the
4263 // output from the concurrent mark thread interfering with this
4264 // logging output either.
4265
4266 _hrs.verify_optional();
4267 verify_region_sets_optional();
4268
4269 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4270 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4271
4272 print_heap_after_gc();
4273 trace_heap_after_gc(_gc_tracer_stw);
4274
4275 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4276 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4277 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4278 // before any GC notifications are raised.
4279 g1mm()->update_sizes();
4280
4281 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4282 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4283 _gc_timer_stw->register_gc_end();
4284 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4285 }
4286 // It should now be safe to tell the concurrent mark thread to start
4287 // without its logging output interfering with the logging output
4288 // that came from the pause.
4289
4290 if (should_start_conc_mark) {
4291 // CAUTION: after the doConcurrentMark() call below,
4292 // the concurrent marking thread(s) could be running
4293 // concurrently with us. Make sure that anything after
4294 // this point does not assume that we are the only GC thread
4295 // running. Note: of course, the actual marking work will
4296 // not start until the safepoint itself is released in
4297 // SuspendibleThreadSet::desynchronize().
4298 doConcurrentMark();
4299 }
4300
4301 return true;
4302 }
4303
4304 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4305 {
4306 size_t gclab_word_size;
4307 switch (purpose) {
4308 case GCAllocForSurvived:
4309 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4310 break;
4311 case GCAllocForTenured:
4312 gclab_word_size = _old_plab_stats.desired_plab_sz();
4313 break;
4314 default:
4315 assert(false, "unknown GCAllocPurpose");
4316 gclab_word_size = _old_plab_stats.desired_plab_sz();
4317 break;
4318 }
4319
4320 // Prevent humongous PLAB sizes for two reasons:
4321 // * PLABs are allocated using a similar paths as oops, but should
4322 // never be in a humongous region
4323 // * Allowing humongous PLABs needlessly churns the region free lists
4324 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4325 }
4326
4327 void G1CollectedHeap::init_mutator_alloc_region() {
4328 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4329 _mutator_alloc_region.init();
4330 }
4331
4332 void G1CollectedHeap::release_mutator_alloc_region() {
4333 _mutator_alloc_region.release();
4334 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4335 }
4336
4337 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4338 assert_at_safepoint(true /* should_be_vm_thread */);
4339
4340 _survivor_gc_alloc_region.init();
4341 _old_gc_alloc_region.init();
4342 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4343 _retained_old_gc_alloc_region = NULL;
4344
4345 // We will discard the current GC alloc region if:
4346 // a) it's in the collection set (it can happen!),
4347 // b) it's already full (no point in using it),
4348 // c) it's empty (this means that it was emptied during
4349 // a cleanup and it should be on the free list now), or
4350 // d) it's humongous (this means that it was emptied
4351 // during a cleanup and was added to the free list, but
4352 // has been subsequently used to allocate a humongous
4353 // object that may be less than the region size).
4354 if (retained_region != NULL &&
4355 !retained_region->in_collection_set() &&
4356 !(retained_region->top() == retained_region->end()) &&
4357 !retained_region->is_empty() &&
4358 !retained_region->isHumongous()) {
4359 retained_region->set_saved_mark();
4360 // The retained region was added to the old region set when it was
4361 // retired. We have to remove it now, since we don't allow regions
4362 // we allocate to in the region sets. We'll re-add it later, when
4363 // it's retired again.
4364 _old_set.remove(retained_region);
4365 bool during_im = g1_policy()->during_initial_mark_pause();
4366 retained_region->note_start_of_copying(during_im);
4367 _old_gc_alloc_region.set(retained_region);
4368 _hr_printer.reuse(retained_region);
4369 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4370 }
4371 }
4372
4373 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4374 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4375 _old_gc_alloc_region.count());
4376 _survivor_gc_alloc_region.release();
4377 // If we have an old GC alloc region to release, we'll save it in
4378 // _retained_old_gc_alloc_region. If we don't
4379 // _retained_old_gc_alloc_region will become NULL. This is what we
4380 // want either way so no reason to check explicitly for either
4381 // condition.
4382 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4383
4384 if (ResizePLAB) {
4385 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4386 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4387 }
4388 }
4389
4390 void G1CollectedHeap::abandon_gc_alloc_regions() {
4391 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4392 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4393 _retained_old_gc_alloc_region = NULL;
4394 }
4395
4396 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4397 _drain_in_progress = false;
4398 set_evac_failure_closure(cl);
4399 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4400 }
4401
4402 void G1CollectedHeap::finalize_for_evac_failure() {
4403 assert(_evac_failure_scan_stack != NULL &&
4404 _evac_failure_scan_stack->length() == 0,
4405 "Postcondition");
4406 assert(!_drain_in_progress, "Postcondition");
4407 delete _evac_failure_scan_stack;
4408 _evac_failure_scan_stack = NULL;
4409 }
4410
4411 void G1CollectedHeap::remove_self_forwarding_pointers() {
4412 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4413
4414 double remove_self_forwards_start = os::elapsedTime();
4415
4416 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4417
4418 if (G1CollectedHeap::use_parallel_gc_threads()) {
4419 set_par_threads();
4420 workers()->run_task(&rsfp_task);
4421 set_par_threads(0);
4422 } else {
4423 rsfp_task.work(0);
4424 }
4425
4426 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4427
4428 // Reset the claim values in the regions in the collection set.
4429 reset_cset_heap_region_claim_values();
4430
4431 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4432
4433 // Now restore saved marks, if any.
4434 assert(_objs_with_preserved_marks.size() ==
4435 _preserved_marks_of_objs.size(), "Both or none.");
4436 while (!_objs_with_preserved_marks.is_empty()) {
4437 oop obj = _objs_with_preserved_marks.pop();
4438 markOop m = _preserved_marks_of_objs.pop();
4439 obj->set_mark(m);
4440 }
4441 _objs_with_preserved_marks.clear(true);
4442 _preserved_marks_of_objs.clear(true);
4443
4444 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4445 }
4446
4447 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4448 _evac_failure_scan_stack->push(obj);
4449 }
4450
4451 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4452 assert(_evac_failure_scan_stack != NULL, "precondition");
4453
4454 while (_evac_failure_scan_stack->length() > 0) {
4455 oop obj = _evac_failure_scan_stack->pop();
4456 _evac_failure_closure->set_region(heap_region_containing(obj));
4457 obj->oop_iterate_backwards(_evac_failure_closure);
4458 }
4459 }
4460
4461 oop
4462 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4463 oop old) {
4464 assert(obj_in_cs(old),
4465 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4466 (HeapWord*) old));
4467 markOop m = old->mark();
4468 oop forward_ptr = old->forward_to_atomic(old);
4469 if (forward_ptr == NULL) {
4470 // Forward-to-self succeeded.
4471 assert(_par_scan_state != NULL, "par scan state");
4472 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4473 uint queue_num = _par_scan_state->queue_num();
4474
4475 _evacuation_failed = true;
4476 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4477 if (_evac_failure_closure != cl) {
4478 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4479 assert(!_drain_in_progress,
4480 "Should only be true while someone holds the lock.");
4481 // Set the global evac-failure closure to the current thread's.
4482 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4483 set_evac_failure_closure(cl);
4484 // Now do the common part.
4485 handle_evacuation_failure_common(old, m);
4486 // Reset to NULL.
4487 set_evac_failure_closure(NULL);
4488 } else {
4489 // The lock is already held, and this is recursive.
4490 assert(_drain_in_progress, "This should only be the recursive case.");
4491 handle_evacuation_failure_common(old, m);
4492 }
4493 return old;
4494 } else {
4495 // Forward-to-self failed. Either someone else managed to allocate
4496 // space for this object (old != forward_ptr) or they beat us in
4497 // self-forwarding it (old == forward_ptr).
4498 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4499 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4500 "should not be in the CSet",
4501 (HeapWord*) old, (HeapWord*) forward_ptr));
4502 return forward_ptr;
4503 }
4504 }
4505
4506 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4507 preserve_mark_if_necessary(old, m);
4508
4509 HeapRegion* r = heap_region_containing(old);
4510 if (!r->evacuation_failed()) {
4511 r->set_evacuation_failed(true);
4512 _hr_printer.evac_failure(r);
4513 }
4514
4515 push_on_evac_failure_scan_stack(old);
4516
4517 if (!_drain_in_progress) {
4518 // prevent recursion in copy_to_survivor_space()
4519 _drain_in_progress = true;
4520 drain_evac_failure_scan_stack();
4521 _drain_in_progress = false;
4522 }
4523 }
4524
4525 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4526 assert(evacuation_failed(), "Oversaving!");
4527 // We want to call the "for_promotion_failure" version only in the
4528 // case of a promotion failure.
4529 if (m->must_be_preserved_for_promotion_failure(obj)) {
4530 _objs_with_preserved_marks.push(obj);
4531 _preserved_marks_of_objs.push(m);
4532 }
4533 }
4534
4535 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4536 size_t word_size) {
4537 if (purpose == GCAllocForSurvived) {
4538 HeapWord* result = survivor_attempt_allocation(word_size);
4539 if (result != NULL) {
4540 return result;
4541 } else {
4542 // Let's try to allocate in the old gen in case we can fit the
4543 // object there.
4544 return old_attempt_allocation(word_size);
4545 }
4546 } else {
4547 assert(purpose == GCAllocForTenured, "sanity");
4548 HeapWord* result = old_attempt_allocation(word_size);
4549 if (result != NULL) {
4550 return result;
4551 } else {
4552 // Let's try to allocate in the survivors in case we can fit the
4553 // object there.
4554 return survivor_attempt_allocation(word_size);
4555 }
4556 }
4557
4558 ShouldNotReachHere();
4559 // Trying to keep some compilers happy.
4560 return NULL;
4561 }
4562
4563 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4564 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4565
4566 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4567 : _g1h(g1h),
4568 _refs(g1h->task_queue(queue_num)),
4569 _dcq(&g1h->dirty_card_queue_set()),
4570 _ct_bs(g1h->g1_barrier_set()),
4571 _g1_rem(g1h->g1_rem_set()),
4572 _hash_seed(17), _queue_num(queue_num),
4573 _term_attempts(0),
4574 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4575 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4576 _age_table(false), _scanner(g1h, this, rp),
4577 _strong_roots_time(0), _term_time(0),
4578 _alloc_buffer_waste(0), _undo_waste(0) {
4579 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4580 // we "sacrifice" entry 0 to keep track of surviving bytes for
4581 // non-young regions (where the age is -1)
4582 // We also add a few elements at the beginning and at the end in
4583 // an attempt to eliminate cache contention
4584 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4585 uint array_length = PADDING_ELEM_NUM +
4586 real_length +
4587 PADDING_ELEM_NUM;
4588 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4589 if (_surviving_young_words_base == NULL)
4590 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4591 "Not enough space for young surv histo.");
4592 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4593 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4594
4595 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4596 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4597
4598 _start = os::elapsedTime();
4599 }
4600
4601 void
4602 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4603 {
4604 st->print_raw_cr("GC Termination Stats");
4605 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4606 " ------waste (KiB)------");
4607 st->print_raw_cr("thr ms ms % ms % attempts"
4608 " total alloc undo");
4609 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4610 " ------- ------- -------");
4611 }
4612
4613 void
4614 G1ParScanThreadState::print_termination_stats(int i,
4615 outputStream* const st) const
4616 {
4617 const double elapsed_ms = elapsed_time() * 1000.0;
4618 const double s_roots_ms = strong_roots_time() * 1000.0;
4619 const double term_ms = term_time() * 1000.0;
4620 st->print_cr("%3d %9.2f %9.2f %6.2f "
4621 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4622 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4623 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4624 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4625 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4626 alloc_buffer_waste() * HeapWordSize / K,
4627 undo_waste() * HeapWordSize / K);
4628 }
4629
4630 #ifdef ASSERT
4631 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4632 assert(ref != NULL, "invariant");
4633 assert(UseCompressedOops, "sanity");
4634 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4635 oop p = oopDesc::load_decode_heap_oop(ref);
4636 assert(_g1h->is_in_g1_reserved(p),
4637 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4638 return true;
4639 }
4640
4641 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4642 assert(ref != NULL, "invariant");
4643 if (has_partial_array_mask(ref)) {
4644 // Must be in the collection set--it's already been copied.
4645 oop p = clear_partial_array_mask(ref);
4646 assert(_g1h->obj_in_cs(p),
4647 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4648 } else {
4649 oop p = oopDesc::load_decode_heap_oop(ref);
4650 assert(_g1h->is_in_g1_reserved(p),
4651 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4652 }
4653 return true;
4654 }
4655
4656 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4657 if (ref.is_narrow()) {
4658 return verify_ref((narrowOop*) ref);
4659 } else {
4660 return verify_ref((oop*) ref);
4661 }
4662 }
4663 #endif // ASSERT
4664
4665 void G1ParScanThreadState::trim_queue() {
4666 assert(_evac_failure_cl != NULL, "not set");
4667
4668 StarTask ref;
4669 do {
4670 // Drain the overflow stack first, so other threads can steal.
4671 while (refs()->pop_overflow(ref)) {
4672 deal_with_reference(ref);
4673 }
4674
4675 while (refs()->pop_local(ref)) {
4676 deal_with_reference(ref);
4677 }
4678 } while (!refs()->is_empty());
4679 }
4680
4681 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4682 G1ParScanThreadState* par_scan_state) :
4683 _g1(g1), _par_scan_state(par_scan_state),
4684 _worker_id(par_scan_state->queue_num()) { }
4685
4686 void G1ParCopyHelper::mark_object(oop obj) {
4687 #ifdef ASSERT
4688 HeapRegion* hr = _g1->heap_region_containing(obj);
4689 assert(hr != NULL, "sanity");
4690 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4691 #endif // ASSERT
4692
4693 // We know that the object is not moving so it's safe to read its size.
4694 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4695 }
4696
4697 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4698 #ifdef ASSERT
4699 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4700 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4701 assert(from_obj != to_obj, "should not be self-forwarded");
4702
4703 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4704 assert(from_hr != NULL, "sanity");
4705 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4706
4707 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4708 assert(to_hr != NULL, "sanity");
4709 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4710 #endif // ASSERT
4711
4712 // The object might be in the process of being copied by another
4713 // worker so we cannot trust that its to-space image is
4714 // well-formed. So we have to read its size from its from-space
4715 // image which we know should not be changing.
4716 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4717 }
4718
4719 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4720 size_t word_sz = old->size();
4721 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4722 // +1 to make the -1 indexes valid...
4723 int young_index = from_region->young_index_in_cset()+1;
4724 assert( (from_region->is_young() && young_index > 0) ||
4725 (!from_region->is_young() && young_index == 0), "invariant" );
4726 G1CollectorPolicy* g1p = _g1h->g1_policy();
4727 markOop m = old->mark();
4728 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4729 : m->age();
4730 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4731 word_sz);
4732 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4733 #ifndef PRODUCT
4734 // Should this evacuation fail?
4735 if (_g1h->evacuation_should_fail()) {
4736 if (obj_ptr != NULL) {
4737 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4738 obj_ptr = NULL;
4739 }
4740 }
4741 #endif // !PRODUCT
4742
4743 if (obj_ptr == NULL) {
4744 // This will either forward-to-self, or detect that someone else has
4745 // installed a forwarding pointer.
4746 return _g1h->handle_evacuation_failure_par(this, old);
4747 }
4748
4749 oop obj = oop(obj_ptr);
4750
4751 // We're going to allocate linearly, so might as well prefetch ahead.
4752 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4753
4754 oop forward_ptr = old->forward_to_atomic(obj);
4755 if (forward_ptr == NULL) {
4756 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4757
4758 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4759 // we actually allocated from and update alloc_purpose accordingly
4760 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4761 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4762
4763 if (g1p->track_object_age(alloc_purpose)) {
4764 // We could simply do obj->incr_age(). However, this causes a
4765 // performance issue. obj->incr_age() will first check whether
4766 // the object has a displaced mark by checking its mark word;
4767 // getting the mark word from the new location of the object
4768 // stalls. So, given that we already have the mark word and we
4769 // are about to install it anyway, it's better to increase the
4770 // age on the mark word, when the object does not have a
4771 // displaced mark word. We're not expecting many objects to have
4772 // a displaced marked word, so that case is not optimized
4773 // further (it could be...) and we simply call obj->incr_age().
4774
4775 if (m->has_displaced_mark_helper()) {
4776 // in this case, we have to install the mark word first,
4777 // otherwise obj looks to be forwarded (the old mark word,
4778 // which contains the forward pointer, was copied)
4779 obj->set_mark(m);
4780 obj->incr_age();
4781 } else {
4782 m = m->incr_age();
4783 obj->set_mark(m);
4784 }
4785 age_table()->add(obj, word_sz);
4786 } else {
4787 obj->set_mark(m);
4788 }
4789
4790 if (G1StringDedup::is_enabled()) {
4791 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4792 to_region->is_young(),
4793 queue_num(),
4794 obj);
4795 }
4796
4797 size_t* surv_young_words = surviving_young_words();
4798 surv_young_words[young_index] += word_sz;
4799
4800 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4801 // We keep track of the next start index in the length field of
4802 // the to-space object. The actual length can be found in the
4803 // length field of the from-space object.
4804 arrayOop(obj)->set_length(0);
4805 oop* old_p = set_partial_array_mask(old);
4806 push_on_queue(old_p);
4807 } else {
4808 // No point in using the slower heap_region_containing() method,
4809 // given that we know obj is in the heap.
4810 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4811 obj->oop_iterate_backwards(&_scanner);
4812 }
4813 } else {
4814 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4815 obj = forward_ptr;
4816 }
4817 return obj;
4818 }
4819
4820 template <class T>
4821 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4822 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4823 _scanned_klass->record_modified_oops();
4824 }
4825 }
4826
4827 template <G1Barrier barrier, bool do_mark_object>
4828 template <class T>
4829 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4830 T heap_oop = oopDesc::load_heap_oop(p);
4831
4832 if (oopDesc::is_null(heap_oop)) {
4833 return;
4834 }
4835
4836 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4837
4838 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4839
4840 if (_g1->in_cset_fast_test(obj)) {
4841 oop forwardee;
4842 if (obj->is_forwarded()) {
4843 forwardee = obj->forwardee();
4844 } else {
4845 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4846 }
4847 assert(forwardee != NULL, "forwardee should not be NULL");
4848 oopDesc::encode_store_heap_oop(p, forwardee);
4849 if (do_mark_object && forwardee != obj) {
4850 // If the object is self-forwarded we don't need to explicitly
4851 // mark it, the evacuation failure protocol will do so.
4852 mark_forwarded_object(obj, forwardee);
4853 }
4854
4855 if (barrier == G1BarrierKlass) {
4856 do_klass_barrier(p, forwardee);
4857 }
4858 } else {
4859 // The object is not in collection set. If we're a root scanning
4860 // closure during an initial mark pause (i.e. do_mark_object will
4861 // be true) then attempt to mark the object.
4862 if (do_mark_object) {
4863 mark_object(obj);
4864 }
4865 }
4866
4867 if (barrier == G1BarrierEvac) {
4868 _par_scan_state->update_rs(_from, p, _worker_id);
4869 }
4870 }
4871
4872 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4873 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4874
4875 class G1ParEvacuateFollowersClosure : public VoidClosure {
4876 protected:
4877 G1CollectedHeap* _g1h;
4878 G1ParScanThreadState* _par_scan_state;
4879 RefToScanQueueSet* _queues;
4880 ParallelTaskTerminator* _terminator;
4881
4882 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4883 RefToScanQueueSet* queues() { return _queues; }
4884 ParallelTaskTerminator* terminator() { return _terminator; }
4885
4886 public:
4887 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4888 G1ParScanThreadState* par_scan_state,
4889 RefToScanQueueSet* queues,
4890 ParallelTaskTerminator* terminator)
4891 : _g1h(g1h), _par_scan_state(par_scan_state),
4892 _queues(queues), _terminator(terminator) {}
4893
4894 void do_void();
4895
4896 private:
4897 inline bool offer_termination();
4898 };
4899
4900 bool G1ParEvacuateFollowersClosure::offer_termination() {
4901 G1ParScanThreadState* const pss = par_scan_state();
4902 pss->start_term_time();
4903 const bool res = terminator()->offer_termination();
4904 pss->end_term_time();
4905 return res;
4906 }
4907
4908 void G1ParEvacuateFollowersClosure::do_void() {
4909 StarTask stolen_task;
4910 G1ParScanThreadState* const pss = par_scan_state();
4911 pss->trim_queue();
4912
4913 do {
4914 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4915 assert(pss->verify_task(stolen_task), "sanity");
4916 if (stolen_task.is_narrow()) {
4917 pss->deal_with_reference((narrowOop*) stolen_task);
4918 } else {
4919 pss->deal_with_reference((oop*) stolen_task);
4920 }
4921
4922 // We've just processed a reference and we might have made
4923 // available new entries on the queues. So we have to make sure
4924 // we drain the queues as necessary.
4925 pss->trim_queue();
4926 }
4927 } while (!offer_termination());
4928 }
4929
4930 class G1KlassScanClosure : public KlassClosure {
4931 G1ParCopyHelper* _closure;
4932 bool _process_only_dirty;
4933 int _count;
4934 public:
4935 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4936 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4937 void do_klass(Klass* klass) {
4938 // If the klass has not been dirtied we know that there's
4939 // no references into the young gen and we can skip it.
4940 if (!_process_only_dirty || klass->has_modified_oops()) {
4941 // Clean the klass since we're going to scavenge all the metadata.
4942 klass->clear_modified_oops();
4943
4944 // Tell the closure that this klass is the Klass to scavenge
4945 // and is the one to dirty if oops are left pointing into the young gen.
4946 _closure->set_scanned_klass(klass);
4947
4948 klass->oops_do(_closure);
4949
4950 _closure->set_scanned_klass(NULL);
4951 }
4952 _count++;
4953 }
4954 };
4955
4956 class G1ParTask : public AbstractGangTask {
4957 protected:
4958 G1CollectedHeap* _g1h;
4959 RefToScanQueueSet *_queues;
4960 ParallelTaskTerminator _terminator;
4961 uint _n_workers;
4962
4963 Mutex _stats_lock;
4964 Mutex* stats_lock() { return &_stats_lock; }
4965
4966 size_t getNCards() {
4967 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4968 / G1BlockOffsetSharedArray::N_bytes;
4969 }
4970
4971 public:
4972 G1ParTask(G1CollectedHeap* g1h,
4973 RefToScanQueueSet *task_queues)
4974 : AbstractGangTask("G1 collection"),
4975 _g1h(g1h),
4976 _queues(task_queues),
4977 _terminator(0, _queues),
4978 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4979 {}
4980
4981 RefToScanQueueSet* queues() { return _queues; }
4982
4983 RefToScanQueue *work_queue(int i) {
4984 return queues()->queue(i);
4985 }
4986
4987 ParallelTaskTerminator* terminator() { return &_terminator; }
4988
4989 virtual void set_for_termination(int active_workers) {
4990 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4991 // in the young space (_par_seq_tasks) in the G1 heap
4992 // for SequentialSubTasksDone.
4993 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4994 // both of which need setting by set_n_termination().
4995 _g1h->SharedHeap::set_n_termination(active_workers);
4996 _g1h->set_n_termination(active_workers);
4997 terminator()->reset_for_reuse(active_workers);
4998 _n_workers = active_workers;
4999 }
5000
5001 void work(uint worker_id) {
5002 if (worker_id >= _n_workers) return; // no work needed this round
5003
5004 double start_time_ms = os::elapsedTime() * 1000.0;
5005 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5006
5007 {
5008 ResourceMark rm;
5009 HandleMark hm;
5010
5011 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5012
5013 G1ParScanThreadState pss(_g1h, worker_id, rp);
5014 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5015
5016 pss.set_evac_failure_closure(&evac_failure_cl);
5017
5018 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5019 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5020
5021 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5022 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5023
5024 bool only_young = _g1h->g1_policy()->gcs_are_young();
5025 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5026 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5027
5028 OopClosure* scan_root_cl = &only_scan_root_cl;
5029 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5030
5031 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5032 // We also need to mark copied objects.
5033 scan_root_cl = &scan_mark_root_cl;
5034 scan_klasses_cl = &scan_mark_klasses_cl_s;
5035 }
5036
5037 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5038
5039 // Don't scan the scavengable methods in the code cache as part
5040 // of strong root scanning. The code roots that point into a
5041 // region in the collection set are scanned when we scan the
5042 // region's RSet.
5043 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5044
5045 pss.start_strong_roots();
5046 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5047 SharedHeap::ScanningOption(so),
5048 scan_root_cl,
5049 &push_heap_rs_cl,
5050 scan_klasses_cl,
5051 worker_id);
5052 pss.end_strong_roots();
5053
5054 {
5055 double start = os::elapsedTime();
5056 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5057 evac.do_void();
5058 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5059 double term_ms = pss.term_time()*1000.0;
5060 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5061 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5062 }
5063 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5064 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5065
5066 if (ParallelGCVerbose) {
5067 MutexLocker x(stats_lock());
5068 pss.print_termination_stats(worker_id);
5069 }
5070
5071 assert(pss.refs()->is_empty(), "should be empty");
5072
5073 // Close the inner scope so that the ResourceMark and HandleMark
5074 // destructors are executed here and are included as part of the
5075 // "GC Worker Time".
5076 }
5077
5078 double end_time_ms = os::elapsedTime() * 1000.0;
5079 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5080 }
5081 };
5082
5083 // *** Common G1 Evacuation Stuff
5084
5085 // This method is run in a GC worker.
5086
5087 void
5088 G1CollectedHeap::
5089 g1_process_strong_roots(bool is_scavenging,
5090 ScanningOption so,
5091 OopClosure* scan_non_heap_roots,
5092 OopsInHeapRegionClosure* scan_rs,
5093 G1KlassScanClosure* scan_klasses,
5094 uint worker_i) {
5095
5096 // First scan the strong roots
5097 double ext_roots_start = os::elapsedTime();
5098 double closure_app_time_sec = 0.0;
5099
5100 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5101
5102 process_strong_roots(false, // no scoping; this is parallel code
5103 so,
5104 &buf_scan_non_heap_roots,
5105 scan_klasses
5106 );
5107
5108 // Now the CM ref_processor roots.
5109 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5110 // We need to treat the discovered reference lists of the
5111 // concurrent mark ref processor as roots and keep entries
5112 // (which are added by the marking threads) on them live
5113 // until they can be processed at the end of marking.
5114 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5115 }
5116
5117 // Finish up any enqueued closure apps (attributed as object copy time).
5118 buf_scan_non_heap_roots.done();
5119
5120 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5121
5122 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5123
5124 double ext_root_time_ms =
5125 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5126
5127 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5128
5129 // During conc marking we have to filter the per-thread SATB buffers
5130 // to make sure we remove any oops into the CSet (which will show up
5131 // as implicitly live).
5132 double satb_filtering_ms = 0.0;
5133 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5134 if (mark_in_progress()) {
5135 double satb_filter_start = os::elapsedTime();
5136
5137 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5138
5139 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5140 }
5141 }
5142 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5143
5144 // If this is an initial mark pause, and we're not scanning
5145 // the entire code cache, we need to mark the oops in the
5146 // strong code root lists for the regions that are not in
5147 // the collection set.
5148 // Note all threads participate in this set of root tasks.
5149 double mark_strong_code_roots_ms = 0.0;
5150 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5151 double mark_strong_roots_start = os::elapsedTime();
5152 mark_strong_code_roots(worker_i);
5153 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5154 }
5155 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5156
5157 // Now scan the complement of the collection set.
5158 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5159 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5160
5161 _process_strong_tasks->all_tasks_completed();
5162 }
5163
5164 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5165 private:
5166 BoolObjectClosure* _is_alive;
5167 int _initial_string_table_size;
5168 int _initial_symbol_table_size;
5169
5170 bool _process_strings;
5171 int _strings_processed;
5172 int _strings_removed;
5173
5174 bool _process_symbols;
5175 int _symbols_processed;
5176 int _symbols_removed;
5177
5178 bool _do_in_parallel;
5179 public:
5180 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5181 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5182 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5183 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5184 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5185
5186 _initial_string_table_size = StringTable::the_table()->table_size();
5187 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5188 if (process_strings) {
5189 StringTable::clear_parallel_claimed_index();
5190 }
5191 if (process_symbols) {
5192 SymbolTable::clear_parallel_claimed_index();
5193 }
5194 }
5195
5196 ~G1StringSymbolTableUnlinkTask() {
5197 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5198 err_msg("claim value %d after unlink less than initial string table size %d",
5199 StringTable::parallel_claimed_index(), _initial_string_table_size));
5200 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5201 err_msg("claim value %d after unlink less than initial symbol table size %d",
5202 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5203 }
5204
5205 void work(uint worker_id) {
5206 if (_do_in_parallel) {
5207 int strings_processed = 0;
5208 int strings_removed = 0;
5209 int symbols_processed = 0;
5210 int symbols_removed = 0;
5211 if (_process_strings) {
5212 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5213 Atomic::add(strings_processed, &_strings_processed);
5214 Atomic::add(strings_removed, &_strings_removed);
5215 }
5216 if (_process_symbols) {
5217 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5218 Atomic::add(symbols_processed, &_symbols_processed);
5219 Atomic::add(symbols_removed, &_symbols_removed);
5220 }
5221 } else {
5222 if (_process_strings) {
5223 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5224 }
5225 if (_process_symbols) {
5226 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5227 }
5228 }
5229 }
5230
5231 size_t strings_processed() const { return (size_t)_strings_processed; }
5232 size_t strings_removed() const { return (size_t)_strings_removed; }
5233
5234 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5235 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5236 };
5237
5238 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5239 bool process_strings, bool process_symbols) {
5240 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5241 _g1h->workers()->active_workers() : 1);
5242
5243 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5244 if (G1CollectedHeap::use_parallel_gc_threads()) {
5245 set_par_threads(n_workers);
5246 workers()->run_task(&g1_unlink_task);
5247 set_par_threads(0);
5248 } else {
5249 g1_unlink_task.work(0);
5250 }
5251 if (G1TraceStringSymbolTableScrubbing) {
5252 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5253 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5254 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5255 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5256 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5257 }
5258
5259 if (G1StringDedup::is_enabled()) {
5260 G1StringDedup::unlink(is_alive);
5261 }
5262 }
5263
5264 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
5265 public:
5266 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
5267 *card_ptr = CardTableModRefBS::dirty_card_val();
5268 return true;
5269 }
5270 };
5271
5272 void G1CollectedHeap::redirty_logged_cards() {
5273 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5274 double redirty_logged_cards_start = os::elapsedTime();
5275
5276 RedirtyLoggedCardTableEntryFastClosure redirty;
5277 dirty_card_queue_set().set_closure(&redirty);
5278 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5279
5280 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5281 dcq.merge_bufferlists(&dirty_card_queue_set());
5282 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5283
5284 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5285 }
5286
5287 // Weak Reference Processing support
5288
5289 // An always "is_alive" closure that is used to preserve referents.
5290 // If the object is non-null then it's alive. Used in the preservation
5291 // of referent objects that are pointed to by reference objects
5292 // discovered by the CM ref processor.
5293 class G1AlwaysAliveClosure: public BoolObjectClosure {
5294 G1CollectedHeap* _g1;
5295 public:
5296 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5297 bool do_object_b(oop p) {
5298 if (p != NULL) {
5299 return true;
5300 }
5301 return false;
5302 }
5303 };
5304
5305 bool G1STWIsAliveClosure::do_object_b(oop p) {
5306 // An object is reachable if it is outside the collection set,
5307 // or is inside and copied.
5308 return !_g1->obj_in_cs(p) || p->is_forwarded();
5309 }
5310
5311 // Non Copying Keep Alive closure
5312 class G1KeepAliveClosure: public OopClosure {
5313 G1CollectedHeap* _g1;
5314 public:
5315 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5316 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5317 void do_oop( oop* p) {
5318 oop obj = *p;
5319
5320 if (_g1->obj_in_cs(obj)) {
5321 assert( obj->is_forwarded(), "invariant" );
5322 *p = obj->forwardee();
5323 }
5324 }
5325 };
5326
5327 // Copying Keep Alive closure - can be called from both
5328 // serial and parallel code as long as different worker
5329 // threads utilize different G1ParScanThreadState instances
5330 // and different queues.
5331
5332 class G1CopyingKeepAliveClosure: public OopClosure {
5333 G1CollectedHeap* _g1h;
5334 OopClosure* _copy_non_heap_obj_cl;
5335 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5336 G1ParScanThreadState* _par_scan_state;
5337
5338 public:
5339 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5340 OopClosure* non_heap_obj_cl,
5341 OopsInHeapRegionClosure* metadata_obj_cl,
5342 G1ParScanThreadState* pss):
5343 _g1h(g1h),
5344 _copy_non_heap_obj_cl(non_heap_obj_cl),
5345 _copy_metadata_obj_cl(metadata_obj_cl),
5346 _par_scan_state(pss)
5347 {}
5348
5349 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5350 virtual void do_oop( oop* p) { do_oop_work(p); }
5351
5352 template <class T> void do_oop_work(T* p) {
5353 oop obj = oopDesc::load_decode_heap_oop(p);
5354
5355 if (_g1h->obj_in_cs(obj)) {
5356 // If the referent object has been forwarded (either copied
5357 // to a new location or to itself in the event of an
5358 // evacuation failure) then we need to update the reference
5359 // field and, if both reference and referent are in the G1
5360 // heap, update the RSet for the referent.
5361 //
5362 // If the referent has not been forwarded then we have to keep
5363 // it alive by policy. Therefore we have copy the referent.
5364 //
5365 // If the reference field is in the G1 heap then we can push
5366 // on the PSS queue. When the queue is drained (after each
5367 // phase of reference processing) the object and it's followers
5368 // will be copied, the reference field set to point to the
5369 // new location, and the RSet updated. Otherwise we need to
5370 // use the the non-heap or metadata closures directly to copy
5371 // the referent object and update the pointer, while avoiding
5372 // updating the RSet.
5373
5374 if (_g1h->is_in_g1_reserved(p)) {
5375 _par_scan_state->push_on_queue(p);
5376 } else {
5377 assert(!ClassLoaderDataGraph::contains((address)p),
5378 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5379 PTR_FORMAT, p));
5380 _copy_non_heap_obj_cl->do_oop(p);
5381 }
5382 }
5383 }
5384 };
5385
5386 // Serial drain queue closure. Called as the 'complete_gc'
5387 // closure for each discovered list in some of the
5388 // reference processing phases.
5389
5390 class G1STWDrainQueueClosure: public VoidClosure {
5391 protected:
5392 G1CollectedHeap* _g1h;
5393 G1ParScanThreadState* _par_scan_state;
5394
5395 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5396
5397 public:
5398 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5399 _g1h(g1h),
5400 _par_scan_state(pss)
5401 { }
5402
5403 void do_void() {
5404 G1ParScanThreadState* const pss = par_scan_state();
5405 pss->trim_queue();
5406 }
5407 };
5408
5409 // Parallel Reference Processing closures
5410
5411 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5412 // processing during G1 evacuation pauses.
5413
5414 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5415 private:
5416 G1CollectedHeap* _g1h;
5417 RefToScanQueueSet* _queues;
5418 FlexibleWorkGang* _workers;
5419 int _active_workers;
5420
5421 public:
5422 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5423 FlexibleWorkGang* workers,
5424 RefToScanQueueSet *task_queues,
5425 int n_workers) :
5426 _g1h(g1h),
5427 _queues(task_queues),
5428 _workers(workers),
5429 _active_workers(n_workers)
5430 {
5431 assert(n_workers > 0, "shouldn't call this otherwise");
5432 }
5433
5434 // Executes the given task using concurrent marking worker threads.
5435 virtual void execute(ProcessTask& task);
5436 virtual void execute(EnqueueTask& task);
5437 };
5438
5439 // Gang task for possibly parallel reference processing
5440
5441 class G1STWRefProcTaskProxy: public AbstractGangTask {
5442 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5443 ProcessTask& _proc_task;
5444 G1CollectedHeap* _g1h;
5445 RefToScanQueueSet *_task_queues;
5446 ParallelTaskTerminator* _terminator;
5447
5448 public:
5449 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5450 G1CollectedHeap* g1h,
5451 RefToScanQueueSet *task_queues,
5452 ParallelTaskTerminator* terminator) :
5453 AbstractGangTask("Process reference objects in parallel"),
5454 _proc_task(proc_task),
5455 _g1h(g1h),
5456 _task_queues(task_queues),
5457 _terminator(terminator)
5458 {}
5459
5460 virtual void work(uint worker_id) {
5461 // The reference processing task executed by a single worker.
5462 ResourceMark rm;
5463 HandleMark hm;
5464
5465 G1STWIsAliveClosure is_alive(_g1h);
5466
5467 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5468 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5469
5470 pss.set_evac_failure_closure(&evac_failure_cl);
5471
5472 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5473 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5474
5475 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5476 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5477
5478 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5479 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5480
5481 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5482 // We also need to mark copied objects.
5483 copy_non_heap_cl = ©_mark_non_heap_cl;
5484 copy_metadata_cl = ©_mark_metadata_cl;
5485 }
5486
5487 // Keep alive closure.
5488 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5489
5490 // Complete GC closure
5491 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5492
5493 // Call the reference processing task's work routine.
5494 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5495
5496 // Note we cannot assert that the refs array is empty here as not all
5497 // of the processing tasks (specifically phase2 - pp2_work) execute
5498 // the complete_gc closure (which ordinarily would drain the queue) so
5499 // the queue may not be empty.
5500 }
5501 };
5502
5503 // Driver routine for parallel reference processing.
5504 // Creates an instance of the ref processing gang
5505 // task and has the worker threads execute it.
5506 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5507 assert(_workers != NULL, "Need parallel worker threads.");
5508
5509 ParallelTaskTerminator terminator(_active_workers, _queues);
5510 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5511
5512 _g1h->set_par_threads(_active_workers);
5513 _workers->run_task(&proc_task_proxy);
5514 _g1h->set_par_threads(0);
5515 }
5516
5517 // Gang task for parallel reference enqueueing.
5518
5519 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5520 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5521 EnqueueTask& _enq_task;
5522
5523 public:
5524 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5525 AbstractGangTask("Enqueue reference objects in parallel"),
5526 _enq_task(enq_task)
5527 { }
5528
5529 virtual void work(uint worker_id) {
5530 _enq_task.work(worker_id);
5531 }
5532 };
5533
5534 // Driver routine for parallel reference enqueueing.
5535 // Creates an instance of the ref enqueueing gang
5536 // task and has the worker threads execute it.
5537
5538 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5539 assert(_workers != NULL, "Need parallel worker threads.");
5540
5541 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5542
5543 _g1h->set_par_threads(_active_workers);
5544 _workers->run_task(&enq_task_proxy);
5545 _g1h->set_par_threads(0);
5546 }
5547
5548 // End of weak reference support closures
5549
5550 // Abstract task used to preserve (i.e. copy) any referent objects
5551 // that are in the collection set and are pointed to by reference
5552 // objects discovered by the CM ref processor.
5553
5554 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5555 protected:
5556 G1CollectedHeap* _g1h;
5557 RefToScanQueueSet *_queues;
5558 ParallelTaskTerminator _terminator;
5559 uint _n_workers;
5560
5561 public:
5562 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5563 AbstractGangTask("ParPreserveCMReferents"),
5564 _g1h(g1h),
5565 _queues(task_queues),
5566 _terminator(workers, _queues),
5567 _n_workers(workers)
5568 { }
5569
5570 void work(uint worker_id) {
5571 ResourceMark rm;
5572 HandleMark hm;
5573
5574 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5575 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5576
5577 pss.set_evac_failure_closure(&evac_failure_cl);
5578
5579 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5580
5581
5582 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5583 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5584
5585 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5586 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5587
5588 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5589 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5590
5591 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5592 // We also need to mark copied objects.
5593 copy_non_heap_cl = ©_mark_non_heap_cl;
5594 copy_metadata_cl = ©_mark_metadata_cl;
5595 }
5596
5597 // Is alive closure
5598 G1AlwaysAliveClosure always_alive(_g1h);
5599
5600 // Copying keep alive closure. Applied to referent objects that need
5601 // to be copied.
5602 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5603
5604 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5605
5606 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5607 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5608
5609 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5610 // So this must be true - but assert just in case someone decides to
5611 // change the worker ids.
5612 assert(0 <= worker_id && worker_id < limit, "sanity");
5613 assert(!rp->discovery_is_atomic(), "check this code");
5614
5615 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5616 for (uint idx = worker_id; idx < limit; idx += stride) {
5617 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5618
5619 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5620 while (iter.has_next()) {
5621 // Since discovery is not atomic for the CM ref processor, we
5622 // can see some null referent objects.
5623 iter.load_ptrs(DEBUG_ONLY(true));
5624 oop ref = iter.obj();
5625
5626 // This will filter nulls.
5627 if (iter.is_referent_alive()) {
5628 iter.make_referent_alive();
5629 }
5630 iter.move_to_next();
5631 }
5632 }
5633
5634 // Drain the queue - which may cause stealing
5635 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5636 drain_queue.do_void();
5637 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5638 assert(pss.refs()->is_empty(), "should be");
5639 }
5640 };
5641
5642 // Weak Reference processing during an evacuation pause (part 1).
5643 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5644 double ref_proc_start = os::elapsedTime();
5645
5646 ReferenceProcessor* rp = _ref_processor_stw;
5647 assert(rp->discovery_enabled(), "should have been enabled");
5648
5649 // Any reference objects, in the collection set, that were 'discovered'
5650 // by the CM ref processor should have already been copied (either by
5651 // applying the external root copy closure to the discovered lists, or
5652 // by following an RSet entry).
5653 //
5654 // But some of the referents, that are in the collection set, that these
5655 // reference objects point to may not have been copied: the STW ref
5656 // processor would have seen that the reference object had already
5657 // been 'discovered' and would have skipped discovering the reference,
5658 // but would not have treated the reference object as a regular oop.
5659 // As a result the copy closure would not have been applied to the
5660 // referent object.
5661 //
5662 // We need to explicitly copy these referent objects - the references
5663 // will be processed at the end of remarking.
5664 //
5665 // We also need to do this copying before we process the reference
5666 // objects discovered by the STW ref processor in case one of these
5667 // referents points to another object which is also referenced by an
5668 // object discovered by the STW ref processor.
5669
5670 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5671 no_of_gc_workers == workers()->active_workers(),
5672 "Need to reset active GC workers");
5673
5674 set_par_threads(no_of_gc_workers);
5675 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5676 no_of_gc_workers,
5677 _task_queues);
5678
5679 if (G1CollectedHeap::use_parallel_gc_threads()) {
5680 workers()->run_task(&keep_cm_referents);
5681 } else {
5682 keep_cm_referents.work(0);
5683 }
5684
5685 set_par_threads(0);
5686
5687 // Closure to test whether a referent is alive.
5688 G1STWIsAliveClosure is_alive(this);
5689
5690 // Even when parallel reference processing is enabled, the processing
5691 // of JNI refs is serial and performed serially by the current thread
5692 // rather than by a worker. The following PSS will be used for processing
5693 // JNI refs.
5694
5695 // Use only a single queue for this PSS.
5696 G1ParScanThreadState pss(this, 0, NULL);
5697
5698 // We do not embed a reference processor in the copying/scanning
5699 // closures while we're actually processing the discovered
5700 // reference objects.
5701 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5702
5703 pss.set_evac_failure_closure(&evac_failure_cl);
5704
5705 assert(pss.refs()->is_empty(), "pre-condition");
5706
5707 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5708 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5709
5710 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5711 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5712
5713 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5714 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5715
5716 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5717 // We also need to mark copied objects.
5718 copy_non_heap_cl = ©_mark_non_heap_cl;
5719 copy_metadata_cl = ©_mark_metadata_cl;
5720 }
5721
5722 // Keep alive closure.
5723 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5724
5725 // Serial Complete GC closure
5726 G1STWDrainQueueClosure drain_queue(this, &pss);
5727
5728 // Setup the soft refs policy...
5729 rp->setup_policy(false);
5730
5731 ReferenceProcessorStats stats;
5732 if (!rp->processing_is_mt()) {
5733 // Serial reference processing...
5734 stats = rp->process_discovered_references(&is_alive,
5735 &keep_alive,
5736 &drain_queue,
5737 NULL,
5738 _gc_timer_stw);
5739 } else {
5740 // Parallel reference processing
5741 assert(rp->num_q() == no_of_gc_workers, "sanity");
5742 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5743
5744 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5745 stats = rp->process_discovered_references(&is_alive,
5746 &keep_alive,
5747 &drain_queue,
5748 &par_task_executor,
5749 _gc_timer_stw);
5750 }
5751
5752 _gc_tracer_stw->report_gc_reference_stats(stats);
5753
5754 // We have completed copying any necessary live referent objects.
5755 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5756
5757 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5758 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5759 }
5760
5761 // Weak Reference processing during an evacuation pause (part 2).
5762 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5763 double ref_enq_start = os::elapsedTime();
5764
5765 ReferenceProcessor* rp = _ref_processor_stw;
5766 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5767
5768 // Now enqueue any remaining on the discovered lists on to
5769 // the pending list.
5770 if (!rp->processing_is_mt()) {
5771 // Serial reference processing...
5772 rp->enqueue_discovered_references();
5773 } else {
5774 // Parallel reference enqueueing
5775
5776 assert(no_of_gc_workers == workers()->active_workers(),
5777 "Need to reset active workers");
5778 assert(rp->num_q() == no_of_gc_workers, "sanity");
5779 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5780
5781 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5782 rp->enqueue_discovered_references(&par_task_executor);
5783 }
5784
5785 rp->verify_no_references_recorded();
5786 assert(!rp->discovery_enabled(), "should have been disabled");
5787
5788 // FIXME
5789 // CM's reference processing also cleans up the string and symbol tables.
5790 // Should we do that here also? We could, but it is a serial operation
5791 // and could significantly increase the pause time.
5792
5793 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5794 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5795 }
5796
5797 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5798 _expand_heap_after_alloc_failure = true;
5799 _evacuation_failed = false;
5800
5801 // Should G1EvacuationFailureALot be in effect for this GC?
5802 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5803
5804 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5805
5806 // Disable the hot card cache.
5807 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5808 hot_card_cache->reset_hot_cache_claimed_index();
5809 hot_card_cache->set_use_cache(false);
5810
5811 uint n_workers;
5812 if (G1CollectedHeap::use_parallel_gc_threads()) {
5813 n_workers =
5814 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5815 workers()->active_workers(),
5816 Threads::number_of_non_daemon_threads());
5817 assert(UseDynamicNumberOfGCThreads ||
5818 n_workers == workers()->total_workers(),
5819 "If not dynamic should be using all the workers");
5820 workers()->set_active_workers(n_workers);
5821 set_par_threads(n_workers);
5822 } else {
5823 assert(n_par_threads() == 0,
5824 "Should be the original non-parallel value");
5825 n_workers = 1;
5826 }
5827
5828 G1ParTask g1_par_task(this, _task_queues);
5829
5830 init_for_evac_failure(NULL);
5831
5832 rem_set()->prepare_for_younger_refs_iterate(true);
5833
5834 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5835 double start_par_time_sec = os::elapsedTime();
5836 double end_par_time_sec;
5837
5838 {
5839 StrongRootsScope srs(this);
5840
5841 if (G1CollectedHeap::use_parallel_gc_threads()) {
5842 // The individual threads will set their evac-failure closures.
5843 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5844 // These tasks use ShareHeap::_process_strong_tasks
5845 assert(UseDynamicNumberOfGCThreads ||
5846 workers()->active_workers() == workers()->total_workers(),
5847 "If not dynamic should be using all the workers");
5848 workers()->run_task(&g1_par_task);
5849 } else {
5850 g1_par_task.set_for_termination(n_workers);
5851 g1_par_task.work(0);
5852 }
5853 end_par_time_sec = os::elapsedTime();
5854
5855 // Closing the inner scope will execute the destructor
5856 // for the StrongRootsScope object. We record the current
5857 // elapsed time before closing the scope so that time
5858 // taken for the SRS destructor is NOT included in the
5859 // reported parallel time.
5860 }
5861
5862 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5863 g1_policy()->phase_times()->record_par_time(par_time_ms);
5864
5865 double code_root_fixup_time_ms =
5866 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5867 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5868
5869 set_par_threads(0);
5870
5871 // Process any discovered reference objects - we have
5872 // to do this _before_ we retire the GC alloc regions
5873 // as we may have to copy some 'reachable' referent
5874 // objects (and their reachable sub-graphs) that were
5875 // not copied during the pause.
5876 process_discovered_references(n_workers);
5877
5878 // Weak root processing.
5879 {
5880 G1STWIsAliveClosure is_alive(this);
5881 G1KeepAliveClosure keep_alive(this);
5882 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5883 if (G1StringDedup::is_enabled()) {
5884 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5885 }
5886 }
5887
5888 release_gc_alloc_regions(n_workers, evacuation_info);
5889 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5890
5891 // Reset and re-enable the hot card cache.
5892 // Note the counts for the cards in the regions in the
5893 // collection set are reset when the collection set is freed.
5894 hot_card_cache->reset_hot_cache();
5895 hot_card_cache->set_use_cache(true);
5896
5897 // Migrate the strong code roots attached to each region in
5898 // the collection set. Ideally we would like to do this
5899 // after we have finished the scanning/evacuation of the
5900 // strong code roots for a particular heap region.
5901 migrate_strong_code_roots();
5902
5903 purge_code_root_memory();
5904
5905 if (g1_policy()->during_initial_mark_pause()) {
5906 // Reset the claim values set during marking the strong code roots
5907 reset_heap_region_claim_values();
5908 }
5909
5910 finalize_for_evac_failure();
5911
5912 if (evacuation_failed()) {
5913 remove_self_forwarding_pointers();
5914
5915 // Reset the G1EvacuationFailureALot counters and flags
5916 // Note: the values are reset only when an actual
5917 // evacuation failure occurs.
5918 NOT_PRODUCT(reset_evacuation_should_fail();)
5919 }
5920
5921 // Enqueue any remaining references remaining on the STW
5922 // reference processor's discovered lists. We need to do
5923 // this after the card table is cleaned (and verified) as
5924 // the act of enqueueing entries on to the pending list
5925 // will log these updates (and dirty their associated
5926 // cards). We need these updates logged to update any
5927 // RSets.
5928 enqueue_discovered_references(n_workers);
5929
5930 if (G1DeferredRSUpdate) {
5931 redirty_logged_cards();
5932 }
5933 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5934 }
5935
5936 void G1CollectedHeap::free_region(HeapRegion* hr,
5937 FreeRegionList* free_list,
5938 bool par,
5939 bool locked) {
5940 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5941 assert(!hr->is_empty(), "the region should not be empty");
5942 assert(free_list != NULL, "pre-condition");
5943
5944 // Clear the card counts for this region.
5945 // Note: we only need to do this if the region is not young
5946 // (since we don't refine cards in young regions).
5947 if (!hr->is_young()) {
5948 _cg1r->hot_card_cache()->reset_card_counts(hr);
5949 }
5950 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5951 free_list->add_ordered(hr);
5952 }
5953
5954 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5955 FreeRegionList* free_list,
5956 bool par) {
5957 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5958 assert(free_list != NULL, "pre-condition");
5959
5960 size_t hr_capacity = hr->capacity();
5961 // We need to read this before we make the region non-humongous,
5962 // otherwise the information will be gone.
5963 uint last_index = hr->last_hc_index();
5964 hr->set_notHumongous();
5965 free_region(hr, free_list, par);
5966
5967 uint i = hr->hrs_index() + 1;
5968 while (i < last_index) {
5969 HeapRegion* curr_hr = region_at(i);
5970 assert(curr_hr->continuesHumongous(), "invariant");
5971 curr_hr->set_notHumongous();
5972 free_region(curr_hr, free_list, par);
5973 i += 1;
5974 }
5975 }
5976
5977 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5978 const HeapRegionSetCount& humongous_regions_removed) {
5979 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5980 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5981 _old_set.bulk_remove(old_regions_removed);
5982 _humongous_set.bulk_remove(humongous_regions_removed);
5983 }
5984
5985 }
5986
5987 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5988 assert(list != NULL, "list can't be null");
5989 if (!list->is_empty()) {
5990 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5991 _free_list.add_ordered(list);
5992 }
5993 }
5994
5995 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5996 assert(_summary_bytes_used >= bytes,
5997 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
5998 _summary_bytes_used, bytes));
5999 _summary_bytes_used -= bytes;
6000 }
6001
6002 class G1ParCleanupCTTask : public AbstractGangTask {
6003 G1SATBCardTableModRefBS* _ct_bs;
6004 G1CollectedHeap* _g1h;
6005 HeapRegion* volatile _su_head;
6006 public:
6007 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6008 G1CollectedHeap* g1h) :
6009 AbstractGangTask("G1 Par Cleanup CT Task"),
6010 _ct_bs(ct_bs), _g1h(g1h) { }
6011
6012 void work(uint worker_id) {
6013 HeapRegion* r;
6014 while (r = _g1h->pop_dirty_cards_region()) {
6015 clear_cards(r);
6016 }
6017 }
6018
6019 void clear_cards(HeapRegion* r) {
6020 // Cards of the survivors should have already been dirtied.
6021 if (!r->is_survivor()) {
6022 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6023 }
6024 }
6025 };
6026
6027 #ifndef PRODUCT
6028 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6029 G1CollectedHeap* _g1h;
6030 G1SATBCardTableModRefBS* _ct_bs;
6031 public:
6032 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6033 : _g1h(g1h), _ct_bs(ct_bs) { }
6034 virtual bool doHeapRegion(HeapRegion* r) {
6035 if (r->is_survivor()) {
6036 _g1h->verify_dirty_region(r);
6037 } else {
6038 _g1h->verify_not_dirty_region(r);
6039 }
6040 return false;
6041 }
6042 };
6043
6044 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6045 // All of the region should be clean.
6046 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6047 MemRegion mr(hr->bottom(), hr->end());
6048 ct_bs->verify_not_dirty_region(mr);
6049 }
6050
6051 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6052 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6053 // dirty allocated blocks as they allocate them. The thread that
6054 // retires each region and replaces it with a new one will do a
6055 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6056 // not dirty that area (one less thing to have to do while holding
6057 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6058 // is dirty.
6059 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6060 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6061 if (hr->is_young()) {
6062 ct_bs->verify_g1_young_region(mr);
6063 } else {
6064 ct_bs->verify_dirty_region(mr);
6065 }
6066 }
6067
6068 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6069 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6070 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6071 verify_dirty_region(hr);
6072 }
6073 }
6074
6075 void G1CollectedHeap::verify_dirty_young_regions() {
6076 verify_dirty_young_list(_young_list->first_region());
6077 }
6078 #endif
6079
6080 void G1CollectedHeap::cleanUpCardTable() {
6081 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6082 double start = os::elapsedTime();
6083
6084 {
6085 // Iterate over the dirty cards region list.
6086 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6087
6088 if (G1CollectedHeap::use_parallel_gc_threads()) {
6089 set_par_threads();
6090 workers()->run_task(&cleanup_task);
6091 set_par_threads(0);
6092 } else {
6093 while (_dirty_cards_region_list) {
6094 HeapRegion* r = _dirty_cards_region_list;
6095 cleanup_task.clear_cards(r);
6096 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6097 if (_dirty_cards_region_list == r) {
6098 // The last region.
6099 _dirty_cards_region_list = NULL;
6100 }
6101 r->set_next_dirty_cards_region(NULL);
6102 }
6103 }
6104 #ifndef PRODUCT
6105 if (G1VerifyCTCleanup || VerifyAfterGC) {
6106 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6107 heap_region_iterate(&cleanup_verifier);
6108 }
6109 #endif
6110 }
6111
6112 double elapsed = os::elapsedTime() - start;
6113 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6114 }
6115
6116 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6117 size_t pre_used = 0;
6118 FreeRegionList local_free_list("Local List for CSet Freeing");
6119
6120 double young_time_ms = 0.0;
6121 double non_young_time_ms = 0.0;
6122
6123 // Since the collection set is a superset of the the young list,
6124 // all we need to do to clear the young list is clear its
6125 // head and length, and unlink any young regions in the code below
6126 _young_list->clear();
6127
6128 G1CollectorPolicy* policy = g1_policy();
6129
6130 double start_sec = os::elapsedTime();
6131 bool non_young = true;
6132
6133 HeapRegion* cur = cs_head;
6134 int age_bound = -1;
6135 size_t rs_lengths = 0;
6136
6137 while (cur != NULL) {
6138 assert(!is_on_master_free_list(cur), "sanity");
6139 if (non_young) {
6140 if (cur->is_young()) {
6141 double end_sec = os::elapsedTime();
6142 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6143 non_young_time_ms += elapsed_ms;
6144
6145 start_sec = os::elapsedTime();
6146 non_young = false;
6147 }
6148 } else {
6149 if (!cur->is_young()) {
6150 double end_sec = os::elapsedTime();
6151 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6152 young_time_ms += elapsed_ms;
6153
6154 start_sec = os::elapsedTime();
6155 non_young = true;
6156 }
6157 }
6158
6159 rs_lengths += cur->rem_set()->occupied_locked();
6160
6161 HeapRegion* next = cur->next_in_collection_set();
6162 assert(cur->in_collection_set(), "bad CS");
6163 cur->set_next_in_collection_set(NULL);
6164 cur->set_in_collection_set(false);
6165
6166 if (cur->is_young()) {
6167 int index = cur->young_index_in_cset();
6168 assert(index != -1, "invariant");
6169 assert((uint) index < policy->young_cset_region_length(), "invariant");
6170 size_t words_survived = _surviving_young_words[index];
6171 cur->record_surv_words_in_group(words_survived);
6172
6173 // At this point the we have 'popped' cur from the collection set
6174 // (linked via next_in_collection_set()) but it is still in the
6175 // young list (linked via next_young_region()). Clear the
6176 // _next_young_region field.
6177 cur->set_next_young_region(NULL);
6178 } else {
6179 int index = cur->young_index_in_cset();
6180 assert(index == -1, "invariant");
6181 }
6182
6183 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6184 (!cur->is_young() && cur->young_index_in_cset() == -1),
6185 "invariant" );
6186
6187 if (!cur->evacuation_failed()) {
6188 MemRegion used_mr = cur->used_region();
6189
6190 // And the region is empty.
6191 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6192 pre_used += cur->used();
6193 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6194 } else {
6195 cur->uninstall_surv_rate_group();
6196 if (cur->is_young()) {
6197 cur->set_young_index_in_cset(-1);
6198 }
6199 cur->set_not_young();
6200 cur->set_evacuation_failed(false);
6201 // The region is now considered to be old.
6202 _old_set.add(cur);
6203 evacuation_info.increment_collectionset_used_after(cur->used());
6204 }
6205 cur = next;
6206 }
6207
6208 evacuation_info.set_regions_freed(local_free_list.length());
6209 policy->record_max_rs_lengths(rs_lengths);
6210 policy->cset_regions_freed();
6211
6212 double end_sec = os::elapsedTime();
6213 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6214
6215 if (non_young) {
6216 non_young_time_ms += elapsed_ms;
6217 } else {
6218 young_time_ms += elapsed_ms;
6219 }
6220
6221 prepend_to_freelist(&local_free_list);
6222 decrement_summary_bytes(pre_used);
6223 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6224 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6225 }
6226
6227 // This routine is similar to the above but does not record
6228 // any policy statistics or update free lists; we are abandoning
6229 // the current incremental collection set in preparation of a
6230 // full collection. After the full GC we will start to build up
6231 // the incremental collection set again.
6232 // This is only called when we're doing a full collection
6233 // and is immediately followed by the tearing down of the young list.
6234
6235 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6236 HeapRegion* cur = cs_head;
6237
6238 while (cur != NULL) {
6239 HeapRegion* next = cur->next_in_collection_set();
6240 assert(cur->in_collection_set(), "bad CS");
6241 cur->set_next_in_collection_set(NULL);
6242 cur->set_in_collection_set(false);
6243 cur->set_young_index_in_cset(-1);
6244 cur = next;
6245 }
6246 }
6247
6248 void G1CollectedHeap::set_free_regions_coming() {
6249 if (G1ConcRegionFreeingVerbose) {
6250 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6251 "setting free regions coming");
6252 }
6253
6254 assert(!free_regions_coming(), "pre-condition");
6255 _free_regions_coming = true;
6256 }
6257
6258 void G1CollectedHeap::reset_free_regions_coming() {
6259 assert(free_regions_coming(), "pre-condition");
6260
6261 {
6262 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6263 _free_regions_coming = false;
6264 SecondaryFreeList_lock->notify_all();
6265 }
6266
6267 if (G1ConcRegionFreeingVerbose) {
6268 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6269 "reset free regions coming");
6270 }
6271 }
6272
6273 void G1CollectedHeap::wait_while_free_regions_coming() {
6274 // Most of the time we won't have to wait, so let's do a quick test
6275 // first before we take the lock.
6276 if (!free_regions_coming()) {
6277 return;
6278 }
6279
6280 if (G1ConcRegionFreeingVerbose) {
6281 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6282 "waiting for free regions");
6283 }
6284
6285 {
6286 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6287 while (free_regions_coming()) {
6288 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6289 }
6290 }
6291
6292 if (G1ConcRegionFreeingVerbose) {
6293 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6294 "done waiting for free regions");
6295 }
6296 }
6297
6298 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6299 assert(heap_lock_held_for_gc(),
6300 "the heap lock should already be held by or for this thread");
6301 _young_list->push_region(hr);
6302 }
6303
6304 class NoYoungRegionsClosure: public HeapRegionClosure {
6305 private:
6306 bool _success;
6307 public:
6308 NoYoungRegionsClosure() : _success(true) { }
6309 bool doHeapRegion(HeapRegion* r) {
6310 if (r->is_young()) {
6311 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6312 r->bottom(), r->end());
6313 _success = false;
6314 }
6315 return false;
6316 }
6317 bool success() { return _success; }
6318 };
6319
6320 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6321 bool ret = _young_list->check_list_empty(check_sample);
6322
6323 if (check_heap) {
6324 NoYoungRegionsClosure closure;
6325 heap_region_iterate(&closure);
6326 ret = ret && closure.success();
6327 }
6328
6329 return ret;
6330 }
6331
6332 class TearDownRegionSetsClosure : public HeapRegionClosure {
6333 private:
6334 HeapRegionSet *_old_set;
6335
6336 public:
6337 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6338
6339 bool doHeapRegion(HeapRegion* r) {
6340 if (r->is_empty()) {
6341 // We ignore empty regions, we'll empty the free list afterwards
6342 } else if (r->is_young()) {
6343 // We ignore young regions, we'll empty the young list afterwards
6344 } else if (r->isHumongous()) {
6345 // We ignore humongous regions, we're not tearing down the
6346 // humongous region set
6347 } else {
6348 // The rest should be old
6349 _old_set->remove(r);
6350 }
6351 return false;
6352 }
6353
6354 ~TearDownRegionSetsClosure() {
6355 assert(_old_set->is_empty(), "post-condition");
6356 }
6357 };
6358
6359 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6360 assert_at_safepoint(true /* should_be_vm_thread */);
6361
6362 if (!free_list_only) {
6363 TearDownRegionSetsClosure cl(&_old_set);
6364 heap_region_iterate(&cl);
6365
6366 // Note that emptying the _young_list is postponed and instead done as
6367 // the first step when rebuilding the regions sets again. The reason for
6368 // this is that during a full GC string deduplication needs to know if
6369 // a collected region was young or old when the full GC was initiated.
6370 }
6371 _free_list.remove_all();
6372 }
6373
6374 class RebuildRegionSetsClosure : public HeapRegionClosure {
6375 private:
6376 bool _free_list_only;
6377 HeapRegionSet* _old_set;
6378 FreeRegionList* _free_list;
6379 size_t _total_used;
6380
6381 public:
6382 RebuildRegionSetsClosure(bool free_list_only,
6383 HeapRegionSet* old_set, FreeRegionList* free_list) :
6384 _free_list_only(free_list_only),
6385 _old_set(old_set), _free_list(free_list), _total_used(0) {
6386 assert(_free_list->is_empty(), "pre-condition");
6387 if (!free_list_only) {
6388 assert(_old_set->is_empty(), "pre-condition");
6389 }
6390 }
6391
6392 bool doHeapRegion(HeapRegion* r) {
6393 if (r->continuesHumongous()) {
6394 return false;
6395 }
6396
6397 if (r->is_empty()) {
6398 // Add free regions to the free list
6399 _free_list->add_as_tail(r);
6400 } else if (!_free_list_only) {
6401 assert(!r->is_young(), "we should not come across young regions");
6402
6403 if (r->isHumongous()) {
6404 // We ignore humongous regions, we left the humongous set unchanged
6405 } else {
6406 // The rest should be old, add them to the old set
6407 _old_set->add(r);
6408 }
6409 _total_used += r->used();
6410 }
6411
6412 return false;
6413 }
6414
6415 size_t total_used() {
6416 return _total_used;
6417 }
6418 };
6419
6420 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6421 assert_at_safepoint(true /* should_be_vm_thread */);
6422
6423 if (!free_list_only) {
6424 _young_list->empty_list();
6425 }
6426
6427 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6428 heap_region_iterate(&cl);
6429
6430 if (!free_list_only) {
6431 _summary_bytes_used = cl.total_used();
6432 }
6433 assert(_summary_bytes_used == recalculate_used(),
6434 err_msg("inconsistent _summary_bytes_used, "
6435 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6436 _summary_bytes_used, recalculate_used()));
6437 }
6438
6439 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6440 _refine_cte_cl->set_concurrent(concurrent);
6441 }
6442
6443 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6444 HeapRegion* hr = heap_region_containing(p);
6445 if (hr == NULL) {
6446 return false;
6447 } else {
6448 return hr->is_in(p);
6449 }
6450 }
6451
6452 // Methods for the mutator alloc region
6453
6454 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6455 bool force) {
6456 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6457 assert(!force || g1_policy()->can_expand_young_list(),
6458 "if force is true we should be able to expand the young list");
6459 bool young_list_full = g1_policy()->is_young_list_full();
6460 if (force || !young_list_full) {
6461 HeapRegion* new_alloc_region = new_region(word_size,
6462 false /* is_old */,
6463 false /* do_expand */);
6464 if (new_alloc_region != NULL) {
6465 set_region_short_lived_locked(new_alloc_region);
6466 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6467 return new_alloc_region;
6468 }
6469 }
6470 return NULL;
6471 }
6472
6473 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6474 size_t allocated_bytes) {
6475 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6476 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6477
6478 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6479 _summary_bytes_used += allocated_bytes;
6480 _hr_printer.retire(alloc_region);
6481 // We update the eden sizes here, when the region is retired,
6482 // instead of when it's allocated, since this is the point that its
6483 // used space has been recored in _summary_bytes_used.
6484 g1mm()->update_eden_size();
6485 }
6486
6487 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6488 bool force) {
6489 return _g1h->new_mutator_alloc_region(word_size, force);
6490 }
6491
6492 void G1CollectedHeap::set_par_threads() {
6493 // Don't change the number of workers. Use the value previously set
6494 // in the workgroup.
6495 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6496 uint n_workers = workers()->active_workers();
6497 assert(UseDynamicNumberOfGCThreads ||
6498 n_workers == workers()->total_workers(),
6499 "Otherwise should be using the total number of workers");
6500 if (n_workers == 0) {
6501 assert(false, "Should have been set in prior evacuation pause.");
6502 n_workers = ParallelGCThreads;
6503 workers()->set_active_workers(n_workers);
6504 }
6505 set_par_threads(n_workers);
6506 }
6507
6508 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6509 size_t allocated_bytes) {
6510 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6511 }
6512
6513 // Methods for the GC alloc regions
6514
6515 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6516 uint count,
6517 GCAllocPurpose ap) {
6518 assert(FreeList_lock->owned_by_self(), "pre-condition");
6519
6520 if (count < g1_policy()->max_regions(ap)) {
6521 bool survivor = (ap == GCAllocForSurvived);
6522 HeapRegion* new_alloc_region = new_region(word_size,
6523 !survivor,
6524 true /* do_expand */);
6525 if (new_alloc_region != NULL) {
6526 // We really only need to do this for old regions given that we
6527 // should never scan survivors. But it doesn't hurt to do it
6528 // for survivors too.
6529 new_alloc_region->set_saved_mark();
6530 if (survivor) {
6531 new_alloc_region->set_survivor();
6532 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6533 } else {
6534 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6535 }
6536 bool during_im = g1_policy()->during_initial_mark_pause();
6537 new_alloc_region->note_start_of_copying(during_im);
6538 return new_alloc_region;
6539 } else {
6540 g1_policy()->note_alloc_region_limit_reached(ap);
6541 }
6542 }
6543 return NULL;
6544 }
6545
6546 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6547 size_t allocated_bytes,
6548 GCAllocPurpose ap) {
6549 bool during_im = g1_policy()->during_initial_mark_pause();
6550 alloc_region->note_end_of_copying(during_im);
6551 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6552 if (ap == GCAllocForSurvived) {
6553 young_list()->add_survivor_region(alloc_region);
6554 } else {
6555 _old_set.add(alloc_region);
6556 }
6557 _hr_printer.retire(alloc_region);
6558 }
6559
6560 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6561 bool force) {
6562 assert(!force, "not supported for GC alloc regions");
6563 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6564 }
6565
6566 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6567 size_t allocated_bytes) {
6568 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6569 GCAllocForSurvived);
6570 }
6571
6572 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6573 bool force) {
6574 assert(!force, "not supported for GC alloc regions");
6575 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6576 }
6577
6578 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6579 size_t allocated_bytes) {
6580 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6581 GCAllocForTenured);
6582 }
6583 // Heap region set verification
6584
6585 class VerifyRegionListsClosure : public HeapRegionClosure {
6586 private:
6587 HeapRegionSet* _old_set;
6588 HeapRegionSet* _humongous_set;
6589 FreeRegionList* _free_list;
6590
6591 public:
6592 HeapRegionSetCount _old_count;
6593 HeapRegionSetCount _humongous_count;
6594 HeapRegionSetCount _free_count;
6595
6596 VerifyRegionListsClosure(HeapRegionSet* old_set,
6597 HeapRegionSet* humongous_set,
6598 FreeRegionList* free_list) :
6599 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6600 _old_count(), _humongous_count(), _free_count(){ }
6601
6602 bool doHeapRegion(HeapRegion* hr) {
6603 if (hr->continuesHumongous()) {
6604 return false;
6605 }
6606
6607 if (hr->is_young()) {
6608 // TODO
6609 } else if (hr->startsHumongous()) {
6610 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6611 _humongous_count.increment(1u, hr->capacity());
6612 } else if (hr->is_empty()) {
6613 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6614 _free_count.increment(1u, hr->capacity());
6615 } else {
6616 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6617 _old_count.increment(1u, hr->capacity());
6618 }
6619 return false;
6620 }
6621
6622 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6623 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6624 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6625 old_set->total_capacity_bytes(), _old_count.capacity()));
6626
6627 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6628 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6629 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6630
6631 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6632 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6633 free_list->total_capacity_bytes(), _free_count.capacity()));
6634 }
6635 };
6636
6637 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6638 HeapWord* bottom) {
6639 HeapWord* end = bottom + HeapRegion::GrainWords;
6640 MemRegion mr(bottom, end);
6641 assert(_g1_reserved.contains(mr), "invariant");
6642 // This might return NULL if the allocation fails
6643 return new HeapRegion(hrs_index, _bot_shared, mr);
6644 }
6645
6646 void G1CollectedHeap::verify_region_sets() {
6647 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6648
6649 // First, check the explicit lists.
6650 _free_list.verify_list();
6651 {
6652 // Given that a concurrent operation might be adding regions to
6653 // the secondary free list we have to take the lock before
6654 // verifying it.
6655 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6656 _secondary_free_list.verify_list();
6657 }
6658
6659 // If a concurrent region freeing operation is in progress it will
6660 // be difficult to correctly attributed any free regions we come
6661 // across to the correct free list given that they might belong to
6662 // one of several (free_list, secondary_free_list, any local lists,
6663 // etc.). So, if that's the case we will skip the rest of the
6664 // verification operation. Alternatively, waiting for the concurrent
6665 // operation to complete will have a non-trivial effect on the GC's
6666 // operation (no concurrent operation will last longer than the
6667 // interval between two calls to verification) and it might hide
6668 // any issues that we would like to catch during testing.
6669 if (free_regions_coming()) {
6670 return;
6671 }
6672
6673 // Make sure we append the secondary_free_list on the free_list so
6674 // that all free regions we will come across can be safely
6675 // attributed to the free_list.
6676 append_secondary_free_list_if_not_empty_with_lock();
6677
6678 // Finally, make sure that the region accounting in the lists is
6679 // consistent with what we see in the heap.
6680
6681 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6682 heap_region_iterate(&cl);
6683 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6684 }
6685
6686 // Optimized nmethod scanning
6687
6688 class RegisterNMethodOopClosure: public OopClosure {
6689 G1CollectedHeap* _g1h;
6690 nmethod* _nm;
6691
6692 template <class T> void do_oop_work(T* p) {
6693 T heap_oop = oopDesc::load_heap_oop(p);
6694 if (!oopDesc::is_null(heap_oop)) {
6695 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6696 HeapRegion* hr = _g1h->heap_region_containing(obj);
6697 assert(!hr->continuesHumongous(),
6698 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6699 " starting at "HR_FORMAT,
6700 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6701
6702 // HeapRegion::add_strong_code_root() avoids adding duplicate
6703 // entries but having duplicates is OK since we "mark" nmethods
6704 // as visited when we scan the strong code root lists during the GC.
6705 hr->add_strong_code_root(_nm);
6706 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6707 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6708 _nm, HR_FORMAT_PARAMS(hr)));
6709 }
6710 }
6711
6712 public:
6713 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6714 _g1h(g1h), _nm(nm) {}
6715
6716 void do_oop(oop* p) { do_oop_work(p); }
6717 void do_oop(narrowOop* p) { do_oop_work(p); }
6718 };
6719
6720 class UnregisterNMethodOopClosure: public OopClosure {
6721 G1CollectedHeap* _g1h;
6722 nmethod* _nm;
6723
6724 template <class T> void do_oop_work(T* p) {
6725 T heap_oop = oopDesc::load_heap_oop(p);
6726 if (!oopDesc::is_null(heap_oop)) {
6727 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6728 HeapRegion* hr = _g1h->heap_region_containing(obj);
6729 assert(!hr->continuesHumongous(),
6730 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6731 " starting at "HR_FORMAT,
6732 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6733
6734 hr->remove_strong_code_root(_nm);
6735 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6736 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6737 _nm, HR_FORMAT_PARAMS(hr)));
6738 }
6739 }
6740
6741 public:
6742 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6743 _g1h(g1h), _nm(nm) {}
6744
6745 void do_oop(oop* p) { do_oop_work(p); }
6746 void do_oop(narrowOop* p) { do_oop_work(p); }
6747 };
6748
6749 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6750 CollectedHeap::register_nmethod(nm);
6751
6752 guarantee(nm != NULL, "sanity");
6753 RegisterNMethodOopClosure reg_cl(this, nm);
6754 nm->oops_do(®_cl);
6755 }
6756
6757 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6758 CollectedHeap::unregister_nmethod(nm);
6759
6760 guarantee(nm != NULL, "sanity");
6761 UnregisterNMethodOopClosure reg_cl(this, nm);
6762 nm->oops_do(®_cl, true);
6763 }
6764
6765 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6766 public:
6767 bool doHeapRegion(HeapRegion *hr) {
6768 assert(!hr->isHumongous(),
6769 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6770 HR_FORMAT_PARAMS(hr)));
6771 hr->migrate_strong_code_roots();
6772 return false;
6773 }
6774 };
6775
6776 void G1CollectedHeap::migrate_strong_code_roots() {
6777 MigrateCodeRootsHeapRegionClosure cl;
6778 double migrate_start = os::elapsedTime();
6779 collection_set_iterate(&cl);
6780 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6781 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6782 }
6783
6784 void G1CollectedHeap::purge_code_root_memory() {
6785 double purge_start = os::elapsedTime();
6786 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6787 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6788 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6789 }
6790
6791 // Mark all the code roots that point into regions *not* in the
6792 // collection set.
6793 //
6794 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6795 // walking the the code roots lists of regions not in the collection
6796 // set. Suppose we have an nmethod (M) that points to objects in two
6797 // separate regions - one in the collection set (R1) and one not (R2).
6798 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6799 // nmethod M when walking the code roots for R1. When we come to scan
6800 // the code roots for R2, we would see that M is already marked and it
6801 // would be skipped and the objects in R2 that are referenced from M
6802 // would not be evacuated.
6803
6804 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6805
6806 class MarkStrongCodeRootOopClosure: public OopClosure {
6807 ConcurrentMark* _cm;
6808 HeapRegion* _hr;
6809 uint _worker_id;
6810
6811 template <class T> void do_oop_work(T* p) {
6812 T heap_oop = oopDesc::load_heap_oop(p);
6813 if (!oopDesc::is_null(heap_oop)) {
6814 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6815 // Only mark objects in the region (which is assumed
6816 // to be not in the collection set).
6817 if (_hr->is_in(obj)) {
6818 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6819 }
6820 }
6821 }
6822
6823 public:
6824 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6825 _cm(cm), _hr(hr), _worker_id(worker_id) {
6826 assert(!_hr->in_collection_set(), "sanity");
6827 }
6828
6829 void do_oop(narrowOop* p) { do_oop_work(p); }
6830 void do_oop(oop* p) { do_oop_work(p); }
6831 };
6832
6833 MarkStrongCodeRootOopClosure _oop_cl;
6834
6835 public:
6836 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6837 _oop_cl(cm, hr, worker_id) {}
6838
6839 void do_code_blob(CodeBlob* cb) {
6840 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6841 if (nm != NULL) {
6842 nm->oops_do(&_oop_cl);
6843 }
6844 }
6845 };
6846
6847 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6848 G1CollectedHeap* _g1h;
6849 uint _worker_id;
6850
6851 public:
6852 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6853 _g1h(g1h), _worker_id(worker_id) {}
6854
6855 bool doHeapRegion(HeapRegion *hr) {
6856 HeapRegionRemSet* hrrs = hr->rem_set();
6857 if (hr->continuesHumongous()) {
6858 // Code roots should never be attached to a continuation of a humongous region
6859 assert(hrrs->strong_code_roots_list_length() == 0,
6860 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6861 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6862 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6863 hrrs->strong_code_roots_list_length()));
6864 return false;
6865 }
6866
6867 if (hr->in_collection_set()) {
6868 // Don't mark code roots into regions in the collection set here.
6869 // They will be marked when we scan them.
6870 return false;
6871 }
6872
6873 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6874 hr->strong_code_roots_do(&cb_cl);
6875 return false;
6876 }
6877 };
6878
6879 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6880 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6881 if (G1CollectedHeap::use_parallel_gc_threads()) {
6882 heap_region_par_iterate_chunked(&cl,
6883 worker_id,
6884 workers()->active_workers(),
6885 HeapRegion::ParMarkRootClaimValue);
6886 } else {
6887 heap_region_iterate(&cl);
6888 }
6889 }
6890
6891 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6892 G1CollectedHeap* _g1h;
6893
6894 public:
6895 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6896 _g1h(g1h) {}
6897
6898 void do_code_blob(CodeBlob* cb) {
6899 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6900 if (nm == NULL) {
6901 return;
6902 }
6903
6904 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6905 _g1h->register_nmethod(nm);
6906 }
6907 }
6908 };
6909
6910 void G1CollectedHeap::rebuild_strong_code_roots() {
6911 RebuildStrongCodeRootClosure blob_cl(this);
6912 CodeCache::blobs_do(&blob_cl);
6913 }