1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/stringTable.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "gc_implementation/g1/bufferingOopClosure.hpp"
35 #include "gc_implementation/g1/concurrentG1Refine.hpp"
36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
40 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
41 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
42 #include "gc_implementation/g1/g1EvacFailure.hpp"
43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
44 #include "gc_implementation/g1/g1Log.hpp"
45 #include "gc_implementation/g1/g1MarkSweep.hpp"
46 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
47 #include "gc_implementation/g1/g1RemSet.inline.hpp"
48 #include "gc_implementation/g1/g1StringDedup.hpp"
49 #include "gc_implementation/g1/g1YCTypes.hpp"
50 #include "gc_implementation/g1/heapRegion.inline.hpp"
51 #include "gc_implementation/g1/heapRegionRemSet.hpp"
52 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
53 #include "gc_implementation/g1/vm_operations_g1.hpp"
54 #include "gc_implementation/shared/gcHeapSummary.hpp"
55 #include "gc_implementation/shared/gcTimer.hpp"
56 #include "gc_implementation/shared/gcTrace.hpp"
57 #include "gc_implementation/shared/gcTraceTime.hpp"
58 #include "gc_implementation/shared/isGCActiveMark.hpp"
59 #include "memory/gcLocker.inline.hpp"
60 #include "memory/generationSpec.hpp"
61 #include "memory/iterator.hpp"
62 #include "memory/referenceProcessor.hpp"
63 #include "oops/oop.inline.hpp"
64 #include "oops/oop.pcgc.inline.hpp"
65 #include "runtime/atomic.inline.hpp"
66 #include "runtime/prefetch.inline.hpp"
67 #include "runtime/orderAccess.inline.hpp"
68 #include "runtime/vmThread.hpp"
69 #include "utilities/globalDefinitions.hpp"
70 #include "utilities/ticks.hpp"
71
72 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
73
74 // turn it on so that the contents of the young list (scan-only /
75 // to-be-collected) are printed at "strategic" points before / during
76 // / after the collection --- this is useful for debugging
77 #define YOUNG_LIST_VERBOSE 0
78 // CURRENT STATUS
79 // This file is under construction. Search for "FIXME".
80
81 // INVARIANTS/NOTES
82 //
83 // All allocation activity covered by the G1CollectedHeap interface is
84 // serialized by acquiring the HeapLock. This happens in mem_allocate
85 // and allocate_new_tlab, which are the "entry" points to the
86 // allocation code from the rest of the JVM. (Note that this does not
87 // apply to TLAB allocation, which is not part of this interface: it
88 // is done by clients of this interface.)
89
90 // Notes on implementation of parallelism in different tasks.
91 //
92 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
93 // The number of GC workers is passed to heap_region_par_iterate_chunked().
94 // It does use run_task() which sets _n_workers in the task.
95 // G1ParTask executes g1_process_strong_roots() ->
96 // SharedHeap::process_strong_roots() which calls eventually to
97 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
98 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
99 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
100 //
101
102 // Local to this file.
103
104 class RefineCardTableEntryClosure: public CardTableEntryClosure {
105 bool _concurrent;
106 public:
107 RefineCardTableEntryClosure() : _concurrent(true) { }
108
109 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
110 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
111 // This path is executed by the concurrent refine or mutator threads,
112 // concurrently, and so we do not care if card_ptr contains references
113 // that point into the collection set.
114 assert(!oops_into_cset, "should be");
115
116 if (_concurrent && SuspendibleThreadSet::should_yield()) {
117 // Caller will actually yield.
118 return false;
119 }
120 // Otherwise, we finished successfully; return true.
121 return true;
122 }
123
124 void set_concurrent(bool b) { _concurrent = b; }
125 };
126
127
128 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
129 size_t _num_processed;
130 CardTableModRefBS* _ctbs;
131 int _histo[256];
132
133 public:
134 ClearLoggedCardTableEntryClosure() :
135 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
136 {
137 for (int i = 0; i < 256; i++) _histo[i] = 0;
138 }
139
140 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
141 unsigned char* ujb = (unsigned char*)card_ptr;
142 int ind = (int)(*ujb);
143 _histo[ind]++;
144
145 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
146 _num_processed++;
147
148 return true;
149 }
150
151 size_t num_processed() { return _num_processed; }
152
153 void print_histo() {
154 gclog_or_tty->print_cr("Card table value histogram:");
155 for (int i = 0; i < 256; i++) {
156 if (_histo[i] != 0) {
157 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
158 }
159 }
160 }
161 };
162
163 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
164 private:
165 size_t _num_processed;
166
167 public:
168 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
169
170 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
171 *card_ptr = CardTableModRefBS::dirty_card_val();
172 _num_processed++;
173 return true;
174 }
175
176 size_t num_processed() const { return _num_processed; }
177 };
178
179 YoungList::YoungList(G1CollectedHeap* g1h) :
180 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
181 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
182 guarantee(check_list_empty(false), "just making sure...");
183 }
184
185 void YoungList::push_region(HeapRegion *hr) {
186 assert(!hr->is_young(), "should not already be young");
187 assert(hr->get_next_young_region() == NULL, "cause it should!");
188
189 hr->set_next_young_region(_head);
190 _head = hr;
191
192 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
193 ++_length;
194 }
195
196 void YoungList::add_survivor_region(HeapRegion* hr) {
197 assert(hr->is_survivor(), "should be flagged as survivor region");
198 assert(hr->get_next_young_region() == NULL, "cause it should!");
199
200 hr->set_next_young_region(_survivor_head);
201 if (_survivor_head == NULL) {
202 _survivor_tail = hr;
203 }
204 _survivor_head = hr;
205 ++_survivor_length;
206 }
207
208 void YoungList::empty_list(HeapRegion* list) {
209 while (list != NULL) {
210 HeapRegion* next = list->get_next_young_region();
211 list->set_next_young_region(NULL);
212 list->uninstall_surv_rate_group();
213 list->set_not_young();
214 list = next;
215 }
216 }
217
218 void YoungList::empty_list() {
219 assert(check_list_well_formed(), "young list should be well formed");
220
221 empty_list(_head);
222 _head = NULL;
223 _length = 0;
224
225 empty_list(_survivor_head);
226 _survivor_head = NULL;
227 _survivor_tail = NULL;
228 _survivor_length = 0;
229
230 _last_sampled_rs_lengths = 0;
231
232 assert(check_list_empty(false), "just making sure...");
233 }
234
235 bool YoungList::check_list_well_formed() {
236 bool ret = true;
237
238 uint length = 0;
239 HeapRegion* curr = _head;
240 HeapRegion* last = NULL;
241 while (curr != NULL) {
242 if (!curr->is_young()) {
243 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
244 "incorrectly tagged (y: %d, surv: %d)",
245 curr->bottom(), curr->end(),
246 curr->is_young(), curr->is_survivor());
247 ret = false;
248 }
249 ++length;
250 last = curr;
251 curr = curr->get_next_young_region();
252 }
253 ret = ret && (length == _length);
254
255 if (!ret) {
256 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
257 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
258 length, _length);
259 }
260
261 return ret;
262 }
263
264 bool YoungList::check_list_empty(bool check_sample) {
265 bool ret = true;
266
267 if (_length != 0) {
268 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
269 _length);
270 ret = false;
271 }
272 if (check_sample && _last_sampled_rs_lengths != 0) {
273 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
274 ret = false;
275 }
276 if (_head != NULL) {
277 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
278 ret = false;
279 }
280 if (!ret) {
281 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
282 }
283
284 return ret;
285 }
286
287 void
288 YoungList::rs_length_sampling_init() {
289 _sampled_rs_lengths = 0;
290 _curr = _head;
291 }
292
293 bool
294 YoungList::rs_length_sampling_more() {
295 return _curr != NULL;
296 }
297
298 void
299 YoungList::rs_length_sampling_next() {
300 assert( _curr != NULL, "invariant" );
301 size_t rs_length = _curr->rem_set()->occupied();
302
303 _sampled_rs_lengths += rs_length;
304
305 // The current region may not yet have been added to the
306 // incremental collection set (it gets added when it is
307 // retired as the current allocation region).
308 if (_curr->in_collection_set()) {
309 // Update the collection set policy information for this region
310 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
311 }
312
313 _curr = _curr->get_next_young_region();
314 if (_curr == NULL) {
315 _last_sampled_rs_lengths = _sampled_rs_lengths;
316 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
317 }
318 }
319
320 void
321 YoungList::reset_auxilary_lists() {
322 guarantee( is_empty(), "young list should be empty" );
323 assert(check_list_well_formed(), "young list should be well formed");
324
325 // Add survivor regions to SurvRateGroup.
326 _g1h->g1_policy()->note_start_adding_survivor_regions();
327 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
328
329 int young_index_in_cset = 0;
330 for (HeapRegion* curr = _survivor_head;
331 curr != NULL;
332 curr = curr->get_next_young_region()) {
333 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
334
335 // The region is a non-empty survivor so let's add it to
336 // the incremental collection set for the next evacuation
337 // pause.
338 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
339 young_index_in_cset += 1;
340 }
341 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
342 _g1h->g1_policy()->note_stop_adding_survivor_regions();
343
344 _head = _survivor_head;
345 _length = _survivor_length;
346 if (_survivor_head != NULL) {
347 assert(_survivor_tail != NULL, "cause it shouldn't be");
348 assert(_survivor_length > 0, "invariant");
349 _survivor_tail->set_next_young_region(NULL);
350 }
351
352 // Don't clear the survivor list handles until the start of
353 // the next evacuation pause - we need it in order to re-tag
354 // the survivor regions from this evacuation pause as 'young'
355 // at the start of the next.
356
357 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
358
359 assert(check_list_well_formed(), "young list should be well formed");
360 }
361
362 void YoungList::print() {
363 HeapRegion* lists[] = {_head, _survivor_head};
364 const char* names[] = {"YOUNG", "SURVIVOR"};
365
366 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
367 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
368 HeapRegion *curr = lists[list];
369 if (curr == NULL)
370 gclog_or_tty->print_cr(" empty");
371 while (curr != NULL) {
372 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
373 HR_FORMAT_PARAMS(curr),
374 curr->prev_top_at_mark_start(),
375 curr->next_top_at_mark_start(),
376 curr->age_in_surv_rate_group_cond());
377 curr = curr->get_next_young_region();
378 }
379 }
380
381 gclog_or_tty->cr();
382 }
383
384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
385 {
386 // Claim the right to put the region on the dirty cards region list
387 // by installing a self pointer.
388 HeapRegion* next = hr->get_next_dirty_cards_region();
389 if (next == NULL) {
390 HeapRegion* res = (HeapRegion*)
391 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
392 NULL);
393 if (res == NULL) {
394 HeapRegion* head;
395 do {
396 // Put the region to the dirty cards region list.
397 head = _dirty_cards_region_list;
398 next = (HeapRegion*)
399 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
400 if (next == head) {
401 assert(hr->get_next_dirty_cards_region() == hr,
402 "hr->get_next_dirty_cards_region() != hr");
403 if (next == NULL) {
404 // The last region in the list points to itself.
405 hr->set_next_dirty_cards_region(hr);
406 } else {
407 hr->set_next_dirty_cards_region(next);
408 }
409 }
410 } while (next != head);
411 }
412 }
413 }
414
415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
416 {
417 HeapRegion* head;
418 HeapRegion* hr;
419 do {
420 head = _dirty_cards_region_list;
421 if (head == NULL) {
422 return NULL;
423 }
424 HeapRegion* new_head = head->get_next_dirty_cards_region();
425 if (head == new_head) {
426 // The last region.
427 new_head = NULL;
428 }
429 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
430 head);
431 } while (hr != head);
432 assert(hr != NULL, "invariant");
433 hr->set_next_dirty_cards_region(NULL);
434 return hr;
435 }
436
437 void G1CollectedHeap::stop_conc_gc_threads() {
438 _cg1r->stop();
439 _cmThread->stop();
440 if (G1StringDedup::is_enabled()) {
441 G1StringDedup::stop();
442 }
443 }
444
445 #ifdef ASSERT
446 // A region is added to the collection set as it is retired
447 // so an address p can point to a region which will be in the
448 // collection set but has not yet been retired. This method
449 // therefore is only accurate during a GC pause after all
450 // regions have been retired. It is used for debugging
451 // to check if an nmethod has references to objects that can
452 // be move during a partial collection. Though it can be
453 // inaccurate, it is sufficient for G1 because the conservative
454 // implementation of is_scavengable() for G1 will indicate that
455 // all nmethods must be scanned during a partial collection.
456 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
457 if (p == NULL) {
458 return false;
459 }
460 return heap_region_containing(p)->in_collection_set();
461 }
462 #endif
463
464 // Returns true if the reference points to an object that
465 // can move in an incremental collection.
466 bool G1CollectedHeap::is_scavengable(const void* p) {
467 HeapRegion* hr = heap_region_containing(p);
468 return !hr->isHumongous();
469 }
470
471 void G1CollectedHeap::check_ct_logs_at_safepoint() {
472 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
473 CardTableModRefBS* ct_bs = g1_barrier_set();
474
475 // Count the dirty cards at the start.
476 CountNonCleanMemRegionClosure count1(this);
477 ct_bs->mod_card_iterate(&count1);
478 int orig_count = count1.n();
479
480 // First clear the logged cards.
481 ClearLoggedCardTableEntryClosure clear;
482 dcqs.apply_closure_to_all_completed_buffers(&clear);
483 dcqs.iterate_closure_all_threads(&clear, false);
484 clear.print_histo();
485
486 // Now ensure that there's no dirty cards.
487 CountNonCleanMemRegionClosure count2(this);
488 ct_bs->mod_card_iterate(&count2);
489 if (count2.n() != 0) {
490 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
491 count2.n(), orig_count);
492 }
493 guarantee(count2.n() == 0, "Card table should be clean.");
494
495 RedirtyLoggedCardTableEntryClosure redirty;
496 dcqs.apply_closure_to_all_completed_buffers(&redirty);
497 dcqs.iterate_closure_all_threads(&redirty, false);
498 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
499 clear.num_processed(), orig_count);
500 guarantee(redirty.num_processed() == clear.num_processed(),
501 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
502 redirty.num_processed(), clear.num_processed()));
503
504 CountNonCleanMemRegionClosure count3(this);
505 ct_bs->mod_card_iterate(&count3);
506 if (count3.n() != orig_count) {
507 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
508 orig_count, count3.n());
509 guarantee(count3.n() >= orig_count, "Should have restored them all.");
510 }
511 }
512
513 // Private class members.
514
515 G1CollectedHeap* G1CollectedHeap::_g1h;
516
517 // Private methods.
518
519 HeapRegion*
520 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
521 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
522 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
523 if (!_secondary_free_list.is_empty()) {
524 if (G1ConcRegionFreeingVerbose) {
525 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
526 "secondary_free_list has %u entries",
527 _secondary_free_list.length());
528 }
529 // It looks as if there are free regions available on the
530 // secondary_free_list. Let's move them to the free_list and try
531 // again to allocate from it.
532 append_secondary_free_list();
533
534 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
535 "empty we should have moved at least one entry to the free_list");
536 HeapRegion* res = _free_list.remove_region(is_old);
537 if (G1ConcRegionFreeingVerbose) {
538 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
539 "allocated "HR_FORMAT" from secondary_free_list",
540 HR_FORMAT_PARAMS(res));
541 }
542 return res;
543 }
544
545 // Wait here until we get notified either when (a) there are no
546 // more free regions coming or (b) some regions have been moved on
547 // the secondary_free_list.
548 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
549 }
550
551 if (G1ConcRegionFreeingVerbose) {
552 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
553 "could not allocate from secondary_free_list");
554 }
555 return NULL;
556 }
557
558 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
559 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
560 "the only time we use this to allocate a humongous region is "
561 "when we are allocating a single humongous region");
562
563 HeapRegion* res;
564 if (G1StressConcRegionFreeing) {
565 if (!_secondary_free_list.is_empty()) {
566 if (G1ConcRegionFreeingVerbose) {
567 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
568 "forced to look at the secondary_free_list");
569 }
570 res = new_region_try_secondary_free_list(is_old);
571 if (res != NULL) {
572 return res;
573 }
574 }
575 }
576
577 res = _free_list.remove_region(is_old);
578
579 if (res == NULL) {
580 if (G1ConcRegionFreeingVerbose) {
581 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
582 "res == NULL, trying the secondary_free_list");
583 }
584 res = new_region_try_secondary_free_list(is_old);
585 }
586 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
587 // Currently, only attempts to allocate GC alloc regions set
588 // do_expand to true. So, we should only reach here during a
589 // safepoint. If this assumption changes we might have to
590 // reconsider the use of _expand_heap_after_alloc_failure.
591 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
592
593 ergo_verbose1(ErgoHeapSizing,
594 "attempt heap expansion",
595 ergo_format_reason("region allocation request failed")
596 ergo_format_byte("allocation request"),
597 word_size * HeapWordSize);
598 if (expand(word_size * HeapWordSize)) {
599 // Given that expand() succeeded in expanding the heap, and we
600 // always expand the heap by an amount aligned to the heap
601 // region size, the free list should in theory not be empty.
602 // In either case remove_region() will check for NULL.
603 res = _free_list.remove_region(is_old);
604 } else {
605 _expand_heap_after_alloc_failure = false;
606 }
607 }
608 return res;
609 }
610
611 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
612 size_t word_size) {
613 assert(isHumongous(word_size), "word_size should be humongous");
614 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
615
616 uint first = G1_NULL_HRS_INDEX;
617 if (num_regions == 1) {
618 // Only one region to allocate, no need to go through the slower
619 // path. The caller will attempt the expansion if this fails, so
620 // let's not try to expand here too.
621 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
622 if (hr != NULL) {
623 first = hr->hrs_index();
624 } else {
625 first = G1_NULL_HRS_INDEX;
626 }
627 } else {
628 // We can't allocate humongous regions while cleanupComplete() is
629 // running, since some of the regions we find to be empty might not
630 // yet be added to the free list and it is not straightforward to
631 // know which list they are on so that we can remove them. Note
632 // that we only need to do this if we need to allocate more than
633 // one region to satisfy the current humongous allocation
634 // request. If we are only allocating one region we use the common
635 // region allocation code (see above).
636 wait_while_free_regions_coming();
637 append_secondary_free_list_if_not_empty_with_lock();
638
639 if (free_regions() >= num_regions) {
640 first = _hrs.find_contiguous(num_regions);
641 if (first != G1_NULL_HRS_INDEX) {
642 for (uint i = first; i < first + num_regions; ++i) {
643 HeapRegion* hr = region_at(i);
644 assert(hr->is_empty(), "sanity");
645 assert(is_on_master_free_list(hr), "sanity");
646 hr->set_pending_removal(true);
647 }
648 _free_list.remove_all_pending(num_regions);
649 }
650 }
651 }
652 return first;
653 }
654
655 HeapWord*
656 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
657 uint num_regions,
658 size_t word_size) {
659 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
660 assert(isHumongous(word_size), "word_size should be humongous");
661 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
662
663 // Index of last region in the series + 1.
664 uint last = first + num_regions;
665
666 // We need to initialize the region(s) we just discovered. This is
667 // a bit tricky given that it can happen concurrently with
668 // refinement threads refining cards on these regions and
669 // potentially wanting to refine the BOT as they are scanning
670 // those cards (this can happen shortly after a cleanup; see CR
671 // 6991377). So we have to set up the region(s) carefully and in
672 // a specific order.
673
674 // The word size sum of all the regions we will allocate.
675 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
676 assert(word_size <= word_size_sum, "sanity");
677
678 // This will be the "starts humongous" region.
679 HeapRegion* first_hr = region_at(first);
680 // The header of the new object will be placed at the bottom of
681 // the first region.
682 HeapWord* new_obj = first_hr->bottom();
683 // This will be the new end of the first region in the series that
684 // should also match the end of the last region in the series.
685 HeapWord* new_end = new_obj + word_size_sum;
686 // This will be the new top of the first region that will reflect
687 // this allocation.
688 HeapWord* new_top = new_obj + word_size;
689
690 // First, we need to zero the header of the space that we will be
691 // allocating. When we update top further down, some refinement
692 // threads might try to scan the region. By zeroing the header we
693 // ensure that any thread that will try to scan the region will
694 // come across the zero klass word and bail out.
695 //
696 // NOTE: It would not have been correct to have used
697 // CollectedHeap::fill_with_object() and make the space look like
698 // an int array. The thread that is doing the allocation will
699 // later update the object header to a potentially different array
700 // type and, for a very short period of time, the klass and length
701 // fields will be inconsistent. This could cause a refinement
702 // thread to calculate the object size incorrectly.
703 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
704
705 // We will set up the first region as "starts humongous". This
706 // will also update the BOT covering all the regions to reflect
707 // that there is a single object that starts at the bottom of the
708 // first region.
709 first_hr->set_startsHumongous(new_top, new_end);
710
711 // Then, if there are any, we will set up the "continues
712 // humongous" regions.
713 HeapRegion* hr = NULL;
714 for (uint i = first + 1; i < last; ++i) {
715 hr = region_at(i);
716 hr->set_continuesHumongous(first_hr);
717 }
718 // If we have "continues humongous" regions (hr != NULL), then the
719 // end of the last one should match new_end.
720 assert(hr == NULL || hr->end() == new_end, "sanity");
721
722 // Up to this point no concurrent thread would have been able to
723 // do any scanning on any region in this series. All the top
724 // fields still point to bottom, so the intersection between
725 // [bottom,top] and [card_start,card_end] will be empty. Before we
726 // update the top fields, we'll do a storestore to make sure that
727 // no thread sees the update to top before the zeroing of the
728 // object header and the BOT initialization.
729 OrderAccess::storestore();
730
731 // Now that the BOT and the object header have been initialized,
732 // we can update top of the "starts humongous" region.
733 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
734 "new_top should be in this region");
735 first_hr->set_top(new_top);
736 if (_hr_printer.is_active()) {
737 HeapWord* bottom = first_hr->bottom();
738 HeapWord* end = first_hr->orig_end();
739 if ((first + 1) == last) {
740 // the series has a single humongous region
741 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
742 } else {
743 // the series has more than one humongous regions
744 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
745 }
746 }
747
748 // Now, we will update the top fields of the "continues humongous"
749 // regions. The reason we need to do this is that, otherwise,
750 // these regions would look empty and this will confuse parts of
751 // G1. For example, the code that looks for a consecutive number
752 // of empty regions will consider them empty and try to
753 // re-allocate them. We can extend is_empty() to also include
754 // !continuesHumongous(), but it is easier to just update the top
755 // fields here. The way we set top for all regions (i.e., top ==
756 // end for all regions but the last one, top == new_top for the
757 // last one) is actually used when we will free up the humongous
758 // region in free_humongous_region().
759 hr = NULL;
760 for (uint i = first + 1; i < last; ++i) {
761 hr = region_at(i);
762 if ((i + 1) == last) {
763 // last continues humongous region
764 assert(hr->bottom() < new_top && new_top <= hr->end(),
765 "new_top should fall on this region");
766 hr->set_top(new_top);
767 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
768 } else {
769 // not last one
770 assert(new_top > hr->end(), "new_top should be above this region");
771 hr->set_top(hr->end());
772 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
773 }
774 }
775 // If we have continues humongous regions (hr != NULL), then the
776 // end of the last one should match new_end and its top should
777 // match new_top.
778 assert(hr == NULL ||
779 (hr->end() == new_end && hr->top() == new_top), "sanity");
780 check_bitmaps("Humongous Region Allocation", first_hr);
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 check_bitmaps("Full GC Start");
1340 pre_full_gc_dump(gc_timer);
1341
1342 COMPILER2_PRESENT(DerivedPointerTable::clear());
1343
1344 // Disable discovery and empty the discovered lists
1345 // for the CM ref processor.
1346 ref_processor_cm()->disable_discovery();
1347 ref_processor_cm()->abandon_partial_discovery();
1348 ref_processor_cm()->verify_no_references_recorded();
1349
1350 // Abandon current iterations of concurrent marking and concurrent
1351 // refinement, if any are in progress. We have to do this before
1352 // wait_until_scan_finished() below.
1353 concurrent_mark()->abort();
1354
1355 // Make sure we'll choose a new allocation region afterwards.
1356 release_mutator_alloc_region();
1357 abandon_gc_alloc_regions();
1358 g1_rem_set()->cleanupHRRS();
1359
1360 // We should call this after we retire any currently active alloc
1361 // regions so that all the ALLOC / RETIRE events are generated
1362 // before the start GC event.
1363 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1364
1365 // We may have added regions to the current incremental collection
1366 // set between the last GC or pause and now. We need to clear the
1367 // incremental collection set and then start rebuilding it afresh
1368 // after this full GC.
1369 abandon_collection_set(g1_policy()->inc_cset_head());
1370 g1_policy()->clear_incremental_cset();
1371 g1_policy()->stop_incremental_cset_building();
1372
1373 tear_down_region_sets(false /* free_list_only */);
1374 g1_policy()->set_gcs_are_young(true);
1375
1376 // See the comments in g1CollectedHeap.hpp and
1377 // G1CollectedHeap::ref_processing_init() about
1378 // how reference processing currently works in G1.
1379
1380 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1381 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1382
1383 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1384 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1385
1386 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1387 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1388
1389 // Do collection work
1390 {
1391 HandleMark hm; // Discard invalid handles created during gc
1392 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1393 }
1394
1395 assert(free_regions() == 0, "we should not have added any free regions");
1396 rebuild_region_sets(false /* free_list_only */);
1397
1398 // Enqueue any discovered reference objects that have
1399 // not been removed from the discovered lists.
1400 ref_processor_stw()->enqueue_discovered_references();
1401
1402 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1403
1404 MemoryService::track_memory_usage();
1405
1406 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1407 ref_processor_stw()->verify_no_references_recorded();
1408
1409 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1410 ClassLoaderDataGraph::purge();
1411 MetaspaceAux::verify_metrics();
1412
1413 // Note: since we've just done a full GC, concurrent
1414 // marking is no longer active. Therefore we need not
1415 // re-enable reference discovery for the CM ref processor.
1416 // That will be done at the start of the next marking cycle.
1417 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1418 ref_processor_cm()->verify_no_references_recorded();
1419
1420 reset_gc_time_stamp();
1421 // Since everything potentially moved, we will clear all remembered
1422 // sets, and clear all cards. Later we will rebuild remembered
1423 // sets. We will also reset the GC time stamps of the regions.
1424 clear_rsets_post_compaction();
1425 check_gc_time_stamps();
1426
1427 // Resize the heap if necessary.
1428 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1429
1430 if (_hr_printer.is_active()) {
1431 // We should do this after we potentially resize the heap so
1432 // that all the COMMIT / UNCOMMIT events are generated before
1433 // the end GC event.
1434
1435 print_hrs_post_compaction();
1436 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1437 }
1438
1439 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1440 if (hot_card_cache->use_cache()) {
1441 hot_card_cache->reset_card_counts();
1442 hot_card_cache->reset_hot_cache();
1443 }
1444
1445 // Rebuild remembered sets of all regions.
1446 if (G1CollectedHeap::use_parallel_gc_threads()) {
1447 uint n_workers =
1448 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1449 workers()->active_workers(),
1450 Threads::number_of_non_daemon_threads());
1451 assert(UseDynamicNumberOfGCThreads ||
1452 n_workers == workers()->total_workers(),
1453 "If not dynamic should be using all the workers");
1454 workers()->set_active_workers(n_workers);
1455 // Set parallel threads in the heap (_n_par_threads) only
1456 // before a parallel phase and always reset it to 0 after
1457 // the phase so that the number of parallel threads does
1458 // no get carried forward to a serial phase where there
1459 // may be code that is "possibly_parallel".
1460 set_par_threads(n_workers);
1461
1462 ParRebuildRSTask rebuild_rs_task(this);
1463 assert(check_heap_region_claim_values(
1464 HeapRegion::InitialClaimValue), "sanity check");
1465 assert(UseDynamicNumberOfGCThreads ||
1466 workers()->active_workers() == workers()->total_workers(),
1467 "Unless dynamic should use total workers");
1468 // Use the most recent number of active workers
1469 assert(workers()->active_workers() > 0,
1470 "Active workers not properly set");
1471 set_par_threads(workers()->active_workers());
1472 workers()->run_task(&rebuild_rs_task);
1473 set_par_threads(0);
1474 assert(check_heap_region_claim_values(
1475 HeapRegion::RebuildRSClaimValue), "sanity check");
1476 reset_heap_region_claim_values();
1477 } else {
1478 RebuildRSOutOfRegionClosure rebuild_rs(this);
1479 heap_region_iterate(&rebuild_rs);
1480 }
1481
1482 // Rebuild the strong code root lists for each region
1483 rebuild_strong_code_roots();
1484
1485 if (true) { // FIXME
1486 MetaspaceGC::compute_new_size();
1487 }
1488
1489 #ifdef TRACESPINNING
1490 ParallelTaskTerminator::print_termination_counts();
1491 #endif
1492
1493 // Discard all rset updates
1494 JavaThread::dirty_card_queue_set().abandon_logs();
1495 assert(!G1DeferredRSUpdate
1496 || (G1DeferredRSUpdate &&
1497 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1498
1499 _young_list->reset_sampled_info();
1500 // At this point there should be no regions in the
1501 // entire heap tagged as young.
1502 assert(check_young_list_empty(true /* check_heap */),
1503 "young list should be empty at this point");
1504
1505 // Update the number of full collections that have been completed.
1506 increment_old_marking_cycles_completed(false /* concurrent */);
1507
1508 _hrs.verify_optional();
1509 verify_region_sets_optional();
1510
1511 verify_after_gc();
1512
1513 // Clear the previous marking bitmap, if needed for bitmap verification.
1514 // Note we cannot do this when we clear the next marking bitmap in
1515 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1516 // objects marked during a full GC against the previous bitmap.
1517 // But we need to clear it before calling check_bitmaps below since
1518 // the full GC has compacted objects and updated TAMS but not updated
1519 // the prev bitmap.
1520 if (G1VerifyBitmaps) {
1521 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1522 }
1523 check_bitmaps("Full GC End");
1524
1525 // Start a new incremental collection set for the next pause
1526 assert(g1_policy()->collection_set() == NULL, "must be");
1527 g1_policy()->start_incremental_cset_building();
1528
1529 clear_cset_fast_test();
1530
1531 init_mutator_alloc_region();
1532
1533 double end = os::elapsedTime();
1534 g1_policy()->record_full_collection_end();
1535
1536 if (G1Log::fine()) {
1537 g1_policy()->print_heap_transition();
1538 }
1539
1540 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1541 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1542 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1543 // before any GC notifications are raised.
1544 g1mm()->update_sizes();
1545
1546 gc_epilogue(true);
1547 }
1548
1549 if (G1Log::finer()) {
1550 g1_policy()->print_detailed_heap_transition(true /* full */);
1551 }
1552
1553 print_heap_after_gc();
1554 trace_heap_after_gc(gc_tracer);
1555
1556 post_full_gc_dump(gc_timer);
1557
1558 gc_timer->register_gc_end();
1559 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1560 }
1561
1562 return true;
1563 }
1564
1565 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1566 // do_collection() will return whether it succeeded in performing
1567 // the GC. Currently, there is no facility on the
1568 // do_full_collection() API to notify the caller than the collection
1569 // did not succeed (e.g., because it was locked out by the GC
1570 // locker). So, right now, we'll ignore the return value.
1571 bool dummy = do_collection(true, /* explicit_gc */
1572 clear_all_soft_refs,
1573 0 /* word_size */);
1574 }
1575
1576 // This code is mostly copied from TenuredGeneration.
1577 void
1578 G1CollectedHeap::
1579 resize_if_necessary_after_full_collection(size_t word_size) {
1580 // Include the current allocation, if any, and bytes that will be
1581 // pre-allocated to support collections, as "used".
1582 const size_t used_after_gc = used();
1583 const size_t capacity_after_gc = capacity();
1584 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1585
1586 // This is enforced in arguments.cpp.
1587 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1588 "otherwise the code below doesn't make sense");
1589
1590 // We don't have floating point command-line arguments
1591 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1592 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1593 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1594 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1595
1596 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1597 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1598
1599 // We have to be careful here as these two calculations can overflow
1600 // 32-bit size_t's.
1601 double used_after_gc_d = (double) used_after_gc;
1602 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1603 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1604
1605 // Let's make sure that they are both under the max heap size, which
1606 // by default will make them fit into a size_t.
1607 double desired_capacity_upper_bound = (double) max_heap_size;
1608 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1609 desired_capacity_upper_bound);
1610 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1611 desired_capacity_upper_bound);
1612
1613 // We can now safely turn them into size_t's.
1614 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1615 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1616
1617 // This assert only makes sense here, before we adjust them
1618 // with respect to the min and max heap size.
1619 assert(minimum_desired_capacity <= maximum_desired_capacity,
1620 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1621 "maximum_desired_capacity = "SIZE_FORMAT,
1622 minimum_desired_capacity, maximum_desired_capacity));
1623
1624 // Should not be greater than the heap max size. No need to adjust
1625 // it with respect to the heap min size as it's a lower bound (i.e.,
1626 // we'll try to make the capacity larger than it, not smaller).
1627 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1628 // Should not be less than the heap min size. No need to adjust it
1629 // with respect to the heap max size as it's an upper bound (i.e.,
1630 // we'll try to make the capacity smaller than it, not greater).
1631 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1632
1633 if (capacity_after_gc < minimum_desired_capacity) {
1634 // Don't expand unless it's significant
1635 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1636 ergo_verbose4(ErgoHeapSizing,
1637 "attempt heap expansion",
1638 ergo_format_reason("capacity lower than "
1639 "min desired capacity after Full GC")
1640 ergo_format_byte("capacity")
1641 ergo_format_byte("occupancy")
1642 ergo_format_byte_perc("min desired capacity"),
1643 capacity_after_gc, used_after_gc,
1644 minimum_desired_capacity, (double) MinHeapFreeRatio);
1645 expand(expand_bytes);
1646
1647 // No expansion, now see if we want to shrink
1648 } else if (capacity_after_gc > maximum_desired_capacity) {
1649 // Capacity too large, compute shrinking size
1650 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1651 ergo_verbose4(ErgoHeapSizing,
1652 "attempt heap shrinking",
1653 ergo_format_reason("capacity higher than "
1654 "max desired capacity after Full GC")
1655 ergo_format_byte("capacity")
1656 ergo_format_byte("occupancy")
1657 ergo_format_byte_perc("max desired capacity"),
1658 capacity_after_gc, used_after_gc,
1659 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1660 shrink(shrink_bytes);
1661 }
1662 }
1663
1664
1665 HeapWord*
1666 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1667 bool* succeeded) {
1668 assert_at_safepoint(true /* should_be_vm_thread */);
1669
1670 *succeeded = true;
1671 // Let's attempt the allocation first.
1672 HeapWord* result =
1673 attempt_allocation_at_safepoint(word_size,
1674 false /* expect_null_mutator_alloc_region */);
1675 if (result != NULL) {
1676 assert(*succeeded, "sanity");
1677 return result;
1678 }
1679
1680 // In a G1 heap, we're supposed to keep allocation from failing by
1681 // incremental pauses. Therefore, at least for now, we'll favor
1682 // expansion over collection. (This might change in the future if we can
1683 // do something smarter than full collection to satisfy a failed alloc.)
1684 result = expand_and_allocate(word_size);
1685 if (result != NULL) {
1686 assert(*succeeded, "sanity");
1687 return result;
1688 }
1689
1690 // Expansion didn't work, we'll try to do a Full GC.
1691 bool gc_succeeded = do_collection(false, /* explicit_gc */
1692 false, /* clear_all_soft_refs */
1693 word_size);
1694 if (!gc_succeeded) {
1695 *succeeded = false;
1696 return NULL;
1697 }
1698
1699 // Retry the allocation
1700 result = attempt_allocation_at_safepoint(word_size,
1701 true /* expect_null_mutator_alloc_region */);
1702 if (result != NULL) {
1703 assert(*succeeded, "sanity");
1704 return result;
1705 }
1706
1707 // Then, try a Full GC that will collect all soft references.
1708 gc_succeeded = do_collection(false, /* explicit_gc */
1709 true, /* clear_all_soft_refs */
1710 word_size);
1711 if (!gc_succeeded) {
1712 *succeeded = false;
1713 return NULL;
1714 }
1715
1716 // Retry the allocation once more
1717 result = attempt_allocation_at_safepoint(word_size,
1718 true /* expect_null_mutator_alloc_region */);
1719 if (result != NULL) {
1720 assert(*succeeded, "sanity");
1721 return result;
1722 }
1723
1724 assert(!collector_policy()->should_clear_all_soft_refs(),
1725 "Flag should have been handled and cleared prior to this point");
1726
1727 // What else? We might try synchronous finalization later. If the total
1728 // space available is large enough for the allocation, then a more
1729 // complete compaction phase than we've tried so far might be
1730 // appropriate.
1731 assert(*succeeded, "sanity");
1732 return NULL;
1733 }
1734
1735 // Attempting to expand the heap sufficiently
1736 // to support an allocation of the given "word_size". If
1737 // successful, perform the allocation and return the address of the
1738 // allocated block, or else "NULL".
1739
1740 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1741 assert_at_safepoint(true /* should_be_vm_thread */);
1742
1743 verify_region_sets_optional();
1744
1745 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1746 ergo_verbose1(ErgoHeapSizing,
1747 "attempt heap expansion",
1748 ergo_format_reason("allocation request failed")
1749 ergo_format_byte("allocation request"),
1750 word_size * HeapWordSize);
1751 if (expand(expand_bytes)) {
1752 _hrs.verify_optional();
1753 verify_region_sets_optional();
1754 return attempt_allocation_at_safepoint(word_size,
1755 false /* expect_null_mutator_alloc_region */);
1756 }
1757 return NULL;
1758 }
1759
1760 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1761 HeapWord* new_end) {
1762 assert(old_end != new_end, "don't call this otherwise");
1763 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1764
1765 // Update the committed mem region.
1766 _g1_committed.set_end(new_end);
1767 // Tell the card table about the update.
1768 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1769 // Tell the BOT about the update.
1770 _bot_shared->resize(_g1_committed.word_size());
1771 // Tell the hot card cache about the update
1772 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1773 }
1774
1775 bool G1CollectedHeap::expand(size_t expand_bytes) {
1776 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1777 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1778 HeapRegion::GrainBytes);
1779 ergo_verbose2(ErgoHeapSizing,
1780 "expand the heap",
1781 ergo_format_byte("requested expansion amount")
1782 ergo_format_byte("attempted expansion amount"),
1783 expand_bytes, aligned_expand_bytes);
1784
1785 if (_g1_storage.uncommitted_size() == 0) {
1786 ergo_verbose0(ErgoHeapSizing,
1787 "did not expand the heap",
1788 ergo_format_reason("heap already fully expanded"));
1789 return false;
1790 }
1791
1792 // First commit the memory.
1793 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1794 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1795 if (successful) {
1796 // Then propagate this update to the necessary data structures.
1797 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1798 update_committed_space(old_end, new_end);
1799
1800 FreeRegionList expansion_list("Local Expansion List");
1801 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1802 assert(mr.start() == old_end, "post-condition");
1803 // mr might be a smaller region than what was requested if
1804 // expand_by() was unable to allocate the HeapRegion instances
1805 assert(mr.end() <= new_end, "post-condition");
1806
1807 size_t actual_expand_bytes = mr.byte_size();
1808 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1809 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1810 "post-condition");
1811 if (actual_expand_bytes < aligned_expand_bytes) {
1812 // We could not expand _hrs to the desired size. In this case we
1813 // need to shrink the committed space accordingly.
1814 assert(mr.end() < new_end, "invariant");
1815
1816 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1817 // First uncommit the memory.
1818 _g1_storage.shrink_by(diff_bytes);
1819 // Then propagate this update to the necessary data structures.
1820 update_committed_space(new_end, mr.end());
1821 }
1822 _free_list.add_as_tail(&expansion_list);
1823
1824 if (_hr_printer.is_active()) {
1825 HeapWord* curr = mr.start();
1826 while (curr < mr.end()) {
1827 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1828 _hr_printer.commit(curr, curr_end);
1829 curr = curr_end;
1830 }
1831 assert(curr == mr.end(), "post-condition");
1832 }
1833 g1_policy()->record_new_heap_size(n_regions());
1834 } else {
1835 ergo_verbose0(ErgoHeapSizing,
1836 "did not expand the heap",
1837 ergo_format_reason("heap expansion operation failed"));
1838 // The expansion of the virtual storage space was unsuccessful.
1839 // Let's see if it was because we ran out of swap.
1840 if (G1ExitOnExpansionFailure &&
1841 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1842 // We had head room...
1843 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1844 }
1845 }
1846 return successful;
1847 }
1848
1849 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1850 size_t aligned_shrink_bytes =
1851 ReservedSpace::page_align_size_down(shrink_bytes);
1852 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1853 HeapRegion::GrainBytes);
1854 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1855
1856 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1857 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1858 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1859
1860 ergo_verbose3(ErgoHeapSizing,
1861 "shrink the heap",
1862 ergo_format_byte("requested shrinking amount")
1863 ergo_format_byte("aligned shrinking amount")
1864 ergo_format_byte("attempted shrinking amount"),
1865 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1866 if (num_regions_removed > 0) {
1867 _g1_storage.shrink_by(shrunk_bytes);
1868 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1869
1870 if (_hr_printer.is_active()) {
1871 HeapWord* curr = old_end;
1872 while (curr > new_end) {
1873 HeapWord* curr_end = curr;
1874 curr -= HeapRegion::GrainWords;
1875 _hr_printer.uncommit(curr, curr_end);
1876 }
1877 }
1878
1879 _expansion_regions += num_regions_removed;
1880 update_committed_space(old_end, new_end);
1881 HeapRegionRemSet::shrink_heap(n_regions());
1882 g1_policy()->record_new_heap_size(n_regions());
1883 } else {
1884 ergo_verbose0(ErgoHeapSizing,
1885 "did not shrink the heap",
1886 ergo_format_reason("heap shrinking operation failed"));
1887 }
1888 }
1889
1890 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1891 verify_region_sets_optional();
1892
1893 // We should only reach here at the end of a Full GC which means we
1894 // should not not be holding to any GC alloc regions. The method
1895 // below will make sure of that and do any remaining clean up.
1896 abandon_gc_alloc_regions();
1897
1898 // Instead of tearing down / rebuilding the free lists here, we
1899 // could instead use the remove_all_pending() method on free_list to
1900 // remove only the ones that we need to remove.
1901 tear_down_region_sets(true /* free_list_only */);
1902 shrink_helper(shrink_bytes);
1903 rebuild_region_sets(true /* free_list_only */);
1904
1905 _hrs.verify_optional();
1906 verify_region_sets_optional();
1907 }
1908
1909 // Public methods.
1910
1911 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1912 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1913 #endif // _MSC_VER
1914
1915
1916 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1917 SharedHeap(policy_),
1918 _g1_policy(policy_),
1919 _dirty_card_queue_set(false),
1920 _into_cset_dirty_card_queue_set(false),
1921 _is_alive_closure_cm(this),
1922 _is_alive_closure_stw(this),
1923 _ref_processor_cm(NULL),
1924 _ref_processor_stw(NULL),
1925 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1926 _bot_shared(NULL),
1927 _evac_failure_scan_stack(NULL),
1928 _mark_in_progress(false),
1929 _cg1r(NULL), _summary_bytes_used(0),
1930 _g1mm(NULL),
1931 _refine_cte_cl(NULL),
1932 _full_collection(false),
1933 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1934 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1935 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1936 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1937 _free_regions_coming(false),
1938 _young_list(new YoungList(this)),
1939 _gc_time_stamp(0),
1940 _retained_old_gc_alloc_region(NULL),
1941 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1942 _old_plab_stats(OldPLABSize, PLABWeight),
1943 _expand_heap_after_alloc_failure(true),
1944 _surviving_young_words(NULL),
1945 _old_marking_cycles_started(0),
1946 _old_marking_cycles_completed(0),
1947 _concurrent_cycle_started(false),
1948 _in_cset_fast_test(),
1949 _dirty_cards_region_list(NULL),
1950 _worker_cset_start_region(NULL),
1951 _worker_cset_start_region_time_stamp(NULL),
1952 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1953 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1954 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1955 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1956
1957 _g1h = this;
1958 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1959 vm_exit_during_initialization("Failed necessary allocation.");
1960 }
1961
1962 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1963
1964 int n_queues = MAX2((int)ParallelGCThreads, 1);
1965 _task_queues = new RefToScanQueueSet(n_queues);
1966
1967 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1968 assert(n_rem_sets > 0, "Invariant.");
1969
1970 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1971 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1972 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1973
1974 for (int i = 0; i < n_queues; i++) {
1975 RefToScanQueue* q = new RefToScanQueue();
1976 q->initialize();
1977 _task_queues->register_queue(i, q);
1978 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1979 }
1980 clear_cset_start_regions();
1981
1982 // Initialize the G1EvacuationFailureALot counters and flags.
1983 NOT_PRODUCT(reset_evacuation_should_fail();)
1984
1985 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1986 }
1987
1988 jint G1CollectedHeap::initialize() {
1989 CollectedHeap::pre_initialize();
1990 os::enable_vtime();
1991
1992 G1Log::init();
1993
1994 // Necessary to satisfy locking discipline assertions.
1995
1996 MutexLocker x(Heap_lock);
1997
1998 // We have to initialize the printer before committing the heap, as
1999 // it will be used then.
2000 _hr_printer.set_active(G1PrintHeapRegions);
2001
2002 // While there are no constraints in the GC code that HeapWordSize
2003 // be any particular value, there are multiple other areas in the
2004 // system which believe this to be true (e.g. oop->object_size in some
2005 // cases incorrectly returns the size in wordSize units rather than
2006 // HeapWordSize).
2007 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2008
2009 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2010 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2011 size_t heap_alignment = collector_policy()->heap_alignment();
2012
2013 // Ensure that the sizes are properly aligned.
2014 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2015 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2016 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2017
2018 _refine_cte_cl = new RefineCardTableEntryClosure();
2019
2020 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2021
2022 // Reserve the maximum.
2023
2024 // When compressed oops are enabled, the preferred heap base
2025 // is calculated by subtracting the requested size from the
2026 // 32Gb boundary and using the result as the base address for
2027 // heap reservation. If the requested size is not aligned to
2028 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2029 // into the ReservedHeapSpace constructor) then the actual
2030 // base of the reserved heap may end up differing from the
2031 // address that was requested (i.e. the preferred heap base).
2032 // If this happens then we could end up using a non-optimal
2033 // compressed oops mode.
2034
2035 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2036 heap_alignment);
2037
2038 // It is important to do this in a way such that concurrent readers can't
2039 // temporarily think something is in the heap. (I've actually seen this
2040 // happen in asserts: DLD.)
2041 _reserved.set_word_size(0);
2042 _reserved.set_start((HeapWord*)heap_rs.base());
2043 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2044
2045 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2046
2047 // Create the gen rem set (and barrier set) for the entire reserved region.
2048 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2049 set_barrier_set(rem_set()->bs());
2050 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2051 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2052 return JNI_ENOMEM;
2053 }
2054
2055 // Also create a G1 rem set.
2056 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2057
2058 // Carve out the G1 part of the heap.
2059
2060 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2061 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2062 g1_rs.size()/HeapWordSize);
2063
2064 _g1_storage.initialize(g1_rs, 0);
2065 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2066 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2067 (HeapWord*) _g1_reserved.end());
2068 assert(_hrs.max_length() == _expansion_regions,
2069 err_msg("max length: %u expansion regions: %u",
2070 _hrs.max_length(), _expansion_regions));
2071
2072 // Do later initialization work for concurrent refinement.
2073 _cg1r->init();
2074
2075 // 6843694 - ensure that the maximum region index can fit
2076 // in the remembered set structures.
2077 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2078 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2079
2080 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2081 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2082 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2083 "too many cards per region");
2084
2085 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2086
2087 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2088 heap_word_size(init_byte_size));
2089
2090 _g1h = this;
2091
2092 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2093
2094 // Create the ConcurrentMark data structure and thread.
2095 // (Must do this late, so that "max_regions" is defined.)
2096 _cm = new ConcurrentMark(this, heap_rs);
2097 if (_cm == NULL || !_cm->completed_initialization()) {
2098 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2099 return JNI_ENOMEM;
2100 }
2101 _cmThread = _cm->cmThread();
2102
2103 // Initialize the from_card cache structure of HeapRegionRemSet.
2104 HeapRegionRemSet::init_heap(max_regions());
2105
2106 // Now expand into the initial heap size.
2107 if (!expand(init_byte_size)) {
2108 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2109 return JNI_ENOMEM;
2110 }
2111
2112 // Perform any initialization actions delegated to the policy.
2113 g1_policy()->init();
2114
2115 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2116 SATB_Q_FL_lock,
2117 G1SATBProcessCompletedThreshold,
2118 Shared_SATB_Q_lock);
2119
2120 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2121 DirtyCardQ_CBL_mon,
2122 DirtyCardQ_FL_lock,
2123 concurrent_g1_refine()->yellow_zone(),
2124 concurrent_g1_refine()->red_zone(),
2125 Shared_DirtyCardQ_lock);
2126
2127 if (G1DeferredRSUpdate) {
2128 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2129 DirtyCardQ_CBL_mon,
2130 DirtyCardQ_FL_lock,
2131 -1, // never trigger processing
2132 -1, // no limit on length
2133 Shared_DirtyCardQ_lock,
2134 &JavaThread::dirty_card_queue_set());
2135 }
2136
2137 // Initialize the card queue set used to hold cards containing
2138 // references into the collection set.
2139 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2140 DirtyCardQ_CBL_mon,
2141 DirtyCardQ_FL_lock,
2142 -1, // never trigger processing
2143 -1, // no limit on length
2144 Shared_DirtyCardQ_lock,
2145 &JavaThread::dirty_card_queue_set());
2146
2147 // In case we're keeping closure specialization stats, initialize those
2148 // counts and that mechanism.
2149 SpecializationStats::clear();
2150
2151 // Here we allocate the dummy full region that is required by the
2152 // G1AllocRegion class. If we don't pass an address in the reserved
2153 // space here, lots of asserts fire.
2154
2155 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2156 _g1_reserved.start());
2157 // We'll re-use the same region whether the alloc region will
2158 // require BOT updates or not and, if it doesn't, then a non-young
2159 // region will complain that it cannot support allocations without
2160 // BOT updates. So we'll tag the dummy region as young to avoid that.
2161 dummy_region->set_young();
2162 // Make sure it's full.
2163 dummy_region->set_top(dummy_region->end());
2164 G1AllocRegion::setup(this, dummy_region);
2165
2166 init_mutator_alloc_region();
2167
2168 // Do create of the monitoring and management support so that
2169 // values in the heap have been properly initialized.
2170 _g1mm = new G1MonitoringSupport(this);
2171
2172 G1StringDedup::initialize();
2173
2174 return JNI_OK;
2175 }
2176
2177 void G1CollectedHeap::stop() {
2178 #if 0
2179 // Stopping concurrent worker threads is currently disabled until
2180 // some bugs in concurrent mark has been resolve. Without fixing
2181 // those bugs first we risk haning during VM exit when trying to
2182 // stop these threads.
2183
2184 // Abort any ongoing concurrent root region scanning and stop all
2185 // concurrent threads. We do this to make sure these threads do
2186 // not continue to execute and access resources (e.g. gclog_or_tty)
2187 // that are destroyed during shutdown.
2188 _cm->root_regions()->abort();
2189 _cm->root_regions()->wait_until_scan_finished();
2190 stop_conc_gc_threads();
2191 #endif
2192 }
2193
2194 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2195 return HeapRegion::max_region_size();
2196 }
2197
2198 void G1CollectedHeap::ref_processing_init() {
2199 // Reference processing in G1 currently works as follows:
2200 //
2201 // * There are two reference processor instances. One is
2202 // used to record and process discovered references
2203 // during concurrent marking; the other is used to
2204 // record and process references during STW pauses
2205 // (both full and incremental).
2206 // * Both ref processors need to 'span' the entire heap as
2207 // the regions in the collection set may be dotted around.
2208 //
2209 // * For the concurrent marking ref processor:
2210 // * Reference discovery is enabled at initial marking.
2211 // * Reference discovery is disabled and the discovered
2212 // references processed etc during remarking.
2213 // * Reference discovery is MT (see below).
2214 // * Reference discovery requires a barrier (see below).
2215 // * Reference processing may or may not be MT
2216 // (depending on the value of ParallelRefProcEnabled
2217 // and ParallelGCThreads).
2218 // * A full GC disables reference discovery by the CM
2219 // ref processor and abandons any entries on it's
2220 // discovered lists.
2221 //
2222 // * For the STW processor:
2223 // * Non MT discovery is enabled at the start of a full GC.
2224 // * Processing and enqueueing during a full GC is non-MT.
2225 // * During a full GC, references are processed after marking.
2226 //
2227 // * Discovery (may or may not be MT) is enabled at the start
2228 // of an incremental evacuation pause.
2229 // * References are processed near the end of a STW evacuation pause.
2230 // * For both types of GC:
2231 // * Discovery is atomic - i.e. not concurrent.
2232 // * Reference discovery will not need a barrier.
2233
2234 SharedHeap::ref_processing_init();
2235 MemRegion mr = reserved_region();
2236
2237 // Concurrent Mark ref processor
2238 _ref_processor_cm =
2239 new ReferenceProcessor(mr, // span
2240 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2241 // mt processing
2242 (int) ParallelGCThreads,
2243 // degree of mt processing
2244 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2245 // mt discovery
2246 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2247 // degree of mt discovery
2248 false,
2249 // Reference discovery is not atomic
2250 &_is_alive_closure_cm,
2251 // is alive closure
2252 // (for efficiency/performance)
2253 true);
2254 // Setting next fields of discovered
2255 // lists requires a barrier.
2256
2257 // STW ref processor
2258 _ref_processor_stw =
2259 new ReferenceProcessor(mr, // span
2260 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2261 // mt processing
2262 MAX2((int)ParallelGCThreads, 1),
2263 // degree of mt processing
2264 (ParallelGCThreads > 1),
2265 // mt discovery
2266 MAX2((int)ParallelGCThreads, 1),
2267 // degree of mt discovery
2268 true,
2269 // Reference discovery is atomic
2270 &_is_alive_closure_stw,
2271 // is alive closure
2272 // (for efficiency/performance)
2273 false);
2274 // Setting next fields of discovered
2275 // lists does not require a barrier.
2276 }
2277
2278 size_t G1CollectedHeap::capacity() const {
2279 return _g1_committed.byte_size();
2280 }
2281
2282 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2283 assert(!hr->continuesHumongous(), "pre-condition");
2284 hr->reset_gc_time_stamp();
2285 if (hr->startsHumongous()) {
2286 uint first_index = hr->hrs_index() + 1;
2287 uint last_index = hr->last_hc_index();
2288 for (uint i = first_index; i < last_index; i += 1) {
2289 HeapRegion* chr = region_at(i);
2290 assert(chr->continuesHumongous(), "sanity");
2291 chr->reset_gc_time_stamp();
2292 }
2293 }
2294 }
2295
2296 #ifndef PRODUCT
2297 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2298 private:
2299 unsigned _gc_time_stamp;
2300 bool _failures;
2301
2302 public:
2303 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2304 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2305
2306 virtual bool doHeapRegion(HeapRegion* hr) {
2307 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2308 if (_gc_time_stamp != region_gc_time_stamp) {
2309 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2310 "expected %d", HR_FORMAT_PARAMS(hr),
2311 region_gc_time_stamp, _gc_time_stamp);
2312 _failures = true;
2313 }
2314 return false;
2315 }
2316
2317 bool failures() { return _failures; }
2318 };
2319
2320 void G1CollectedHeap::check_gc_time_stamps() {
2321 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2322 heap_region_iterate(&cl);
2323 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2324 }
2325 #endif // PRODUCT
2326
2327 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2328 DirtyCardQueue* into_cset_dcq,
2329 bool concurrent,
2330 uint worker_i) {
2331 // Clean cards in the hot card cache
2332 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2333 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2334
2335 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2336 int n_completed_buffers = 0;
2337 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2338 n_completed_buffers++;
2339 }
2340 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2341 dcqs.clear_n_completed_buffers();
2342 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2343 }
2344
2345
2346 // Computes the sum of the storage used by the various regions.
2347
2348 size_t G1CollectedHeap::used() const {
2349 assert(Heap_lock->owner() != NULL,
2350 "Should be owned on this thread's behalf.");
2351 size_t result = _summary_bytes_used;
2352 // Read only once in case it is set to NULL concurrently
2353 HeapRegion* hr = _mutator_alloc_region.get();
2354 if (hr != NULL)
2355 result += hr->used();
2356 return result;
2357 }
2358
2359 size_t G1CollectedHeap::used_unlocked() const {
2360 size_t result = _summary_bytes_used;
2361 return result;
2362 }
2363
2364 class SumUsedClosure: public HeapRegionClosure {
2365 size_t _used;
2366 public:
2367 SumUsedClosure() : _used(0) {}
2368 bool doHeapRegion(HeapRegion* r) {
2369 if (!r->continuesHumongous()) {
2370 _used += r->used();
2371 }
2372 return false;
2373 }
2374 size_t result() { return _used; }
2375 };
2376
2377 size_t G1CollectedHeap::recalculate_used() const {
2378 double recalculate_used_start = os::elapsedTime();
2379
2380 SumUsedClosure blk;
2381 heap_region_iterate(&blk);
2382
2383 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2384 return blk.result();
2385 }
2386
2387 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2388 switch (cause) {
2389 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2390 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2391 case GCCause::_g1_humongous_allocation: return true;
2392 default: return false;
2393 }
2394 }
2395
2396 #ifndef PRODUCT
2397 void G1CollectedHeap::allocate_dummy_regions() {
2398 // Let's fill up most of the region
2399 size_t word_size = HeapRegion::GrainWords - 1024;
2400 // And as a result the region we'll allocate will be humongous.
2401 guarantee(isHumongous(word_size), "sanity");
2402
2403 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2404 // Let's use the existing mechanism for the allocation
2405 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2406 if (dummy_obj != NULL) {
2407 MemRegion mr(dummy_obj, word_size);
2408 CollectedHeap::fill_with_object(mr);
2409 } else {
2410 // If we can't allocate once, we probably cannot allocate
2411 // again. Let's get out of the loop.
2412 break;
2413 }
2414 }
2415 }
2416 #endif // !PRODUCT
2417
2418 void G1CollectedHeap::increment_old_marking_cycles_started() {
2419 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2420 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2421 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2422 _old_marking_cycles_started, _old_marking_cycles_completed));
2423
2424 _old_marking_cycles_started++;
2425 }
2426
2427 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2428 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2429
2430 // We assume that if concurrent == true, then the caller is a
2431 // concurrent thread that was joined the Suspendible Thread
2432 // Set. If there's ever a cheap way to check this, we should add an
2433 // assert here.
2434
2435 // Given that this method is called at the end of a Full GC or of a
2436 // concurrent cycle, and those can be nested (i.e., a Full GC can
2437 // interrupt a concurrent cycle), the number of full collections
2438 // completed should be either one (in the case where there was no
2439 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2440 // behind the number of full collections started.
2441
2442 // This is the case for the inner caller, i.e. a Full GC.
2443 assert(concurrent ||
2444 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2445 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2446 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2447 "is inconsistent with _old_marking_cycles_completed = %u",
2448 _old_marking_cycles_started, _old_marking_cycles_completed));
2449
2450 // This is the case for the outer caller, i.e. the concurrent cycle.
2451 assert(!concurrent ||
2452 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2453 err_msg("for outer caller (concurrent cycle): "
2454 "_old_marking_cycles_started = %u "
2455 "is inconsistent with _old_marking_cycles_completed = %u",
2456 _old_marking_cycles_started, _old_marking_cycles_completed));
2457
2458 _old_marking_cycles_completed += 1;
2459
2460 // We need to clear the "in_progress" flag in the CM thread before
2461 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2462 // is set) so that if a waiter requests another System.gc() it doesn't
2463 // incorrectly see that a marking cycle is still in progress.
2464 if (concurrent) {
2465 _cmThread->clear_in_progress();
2466 }
2467
2468 // This notify_all() will ensure that a thread that called
2469 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2470 // and it's waiting for a full GC to finish will be woken up. It is
2471 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2472 FullGCCount_lock->notify_all();
2473 }
2474
2475 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2476 _concurrent_cycle_started = true;
2477 _gc_timer_cm->register_gc_start(start_time);
2478
2479 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2480 trace_heap_before_gc(_gc_tracer_cm);
2481 }
2482
2483 void G1CollectedHeap::register_concurrent_cycle_end() {
2484 if (_concurrent_cycle_started) {
2485 if (_cm->has_aborted()) {
2486 _gc_tracer_cm->report_concurrent_mode_failure();
2487 }
2488
2489 _gc_timer_cm->register_gc_end();
2490 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2491
2492 _concurrent_cycle_started = false;
2493 }
2494 }
2495
2496 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2497 if (_concurrent_cycle_started) {
2498 trace_heap_after_gc(_gc_tracer_cm);
2499 }
2500 }
2501
2502 G1YCType G1CollectedHeap::yc_type() {
2503 bool is_young = g1_policy()->gcs_are_young();
2504 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2505 bool is_during_mark = mark_in_progress();
2506
2507 if (is_initial_mark) {
2508 return InitialMark;
2509 } else if (is_during_mark) {
2510 return DuringMark;
2511 } else if (is_young) {
2512 return Normal;
2513 } else {
2514 return Mixed;
2515 }
2516 }
2517
2518 void G1CollectedHeap::collect(GCCause::Cause cause) {
2519 assert_heap_not_locked();
2520
2521 unsigned int gc_count_before;
2522 unsigned int old_marking_count_before;
2523 bool retry_gc;
2524
2525 do {
2526 retry_gc = false;
2527
2528 {
2529 MutexLocker ml(Heap_lock);
2530
2531 // Read the GC count while holding the Heap_lock
2532 gc_count_before = total_collections();
2533 old_marking_count_before = _old_marking_cycles_started;
2534 }
2535
2536 if (should_do_concurrent_full_gc(cause)) {
2537 // Schedule an initial-mark evacuation pause that will start a
2538 // concurrent cycle. We're setting word_size to 0 which means that
2539 // we are not requesting a post-GC allocation.
2540 VM_G1IncCollectionPause op(gc_count_before,
2541 0, /* word_size */
2542 true, /* should_initiate_conc_mark */
2543 g1_policy()->max_pause_time_ms(),
2544 cause);
2545
2546 VMThread::execute(&op);
2547 if (!op.pause_succeeded()) {
2548 if (old_marking_count_before == _old_marking_cycles_started) {
2549 retry_gc = op.should_retry_gc();
2550 } else {
2551 // A Full GC happened while we were trying to schedule the
2552 // initial-mark GC. No point in starting a new cycle given
2553 // that the whole heap was collected anyway.
2554 }
2555
2556 if (retry_gc) {
2557 if (GC_locker::is_active_and_needs_gc()) {
2558 GC_locker::stall_until_clear();
2559 }
2560 }
2561 }
2562 } else {
2563 if (cause == GCCause::_gc_locker
2564 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2565
2566 // Schedule a standard evacuation pause. We're setting word_size
2567 // to 0 which means that we are not requesting a post-GC allocation.
2568 VM_G1IncCollectionPause op(gc_count_before,
2569 0, /* word_size */
2570 false, /* should_initiate_conc_mark */
2571 g1_policy()->max_pause_time_ms(),
2572 cause);
2573 VMThread::execute(&op);
2574 } else {
2575 // Schedule a Full GC.
2576 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2577 VMThread::execute(&op);
2578 }
2579 }
2580 } while (retry_gc);
2581 }
2582
2583 bool G1CollectedHeap::is_in(const void* p) const {
2584 if (_g1_committed.contains(p)) {
2585 // Given that we know that p is in the committed space,
2586 // heap_region_containing_raw() should successfully
2587 // return the containing region.
2588 HeapRegion* hr = heap_region_containing_raw(p);
2589 return hr->is_in(p);
2590 } else {
2591 return false;
2592 }
2593 }
2594
2595 // Iteration functions.
2596
2597 // Iterates an OopClosure over all ref-containing fields of objects
2598 // within a HeapRegion.
2599
2600 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2601 MemRegion _mr;
2602 ExtendedOopClosure* _cl;
2603 public:
2604 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2605 : _mr(mr), _cl(cl) {}
2606 bool doHeapRegion(HeapRegion* r) {
2607 if (!r->continuesHumongous()) {
2608 r->oop_iterate(_cl);
2609 }
2610 return false;
2611 }
2612 };
2613
2614 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2615 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2616 heap_region_iterate(&blk);
2617 }
2618
2619 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2620 IterateOopClosureRegionClosure blk(mr, cl);
2621 heap_region_iterate(&blk);
2622 }
2623
2624 // Iterates an ObjectClosure over all objects within a HeapRegion.
2625
2626 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2627 ObjectClosure* _cl;
2628 public:
2629 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2630 bool doHeapRegion(HeapRegion* r) {
2631 if (! r->continuesHumongous()) {
2632 r->object_iterate(_cl);
2633 }
2634 return false;
2635 }
2636 };
2637
2638 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2639 IterateObjectClosureRegionClosure blk(cl);
2640 heap_region_iterate(&blk);
2641 }
2642
2643 // Calls a SpaceClosure on a HeapRegion.
2644
2645 class SpaceClosureRegionClosure: public HeapRegionClosure {
2646 SpaceClosure* _cl;
2647 public:
2648 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2649 bool doHeapRegion(HeapRegion* r) {
2650 _cl->do_space(r);
2651 return false;
2652 }
2653 };
2654
2655 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2656 SpaceClosureRegionClosure blk(cl);
2657 heap_region_iterate(&blk);
2658 }
2659
2660 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2661 _hrs.iterate(cl);
2662 }
2663
2664 void
2665 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2666 uint worker_id,
2667 uint no_of_par_workers,
2668 jint claim_value) {
2669 const uint regions = n_regions();
2670 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2671 no_of_par_workers :
2672 1);
2673 assert(UseDynamicNumberOfGCThreads ||
2674 no_of_par_workers == workers()->total_workers(),
2675 "Non dynamic should use fixed number of workers");
2676 // try to spread out the starting points of the workers
2677 const HeapRegion* start_hr =
2678 start_region_for_worker(worker_id, no_of_par_workers);
2679 const uint start_index = start_hr->hrs_index();
2680
2681 // each worker will actually look at all regions
2682 for (uint count = 0; count < regions; ++count) {
2683 const uint index = (start_index + count) % regions;
2684 assert(0 <= index && index < regions, "sanity");
2685 HeapRegion* r = region_at(index);
2686 // we'll ignore "continues humongous" regions (we'll process them
2687 // when we come across their corresponding "start humongous"
2688 // region) and regions already claimed
2689 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2690 continue;
2691 }
2692 // OK, try to claim it
2693 if (r->claimHeapRegion(claim_value)) {
2694 // success!
2695 assert(!r->continuesHumongous(), "sanity");
2696 if (r->startsHumongous()) {
2697 // If the region is "starts humongous" we'll iterate over its
2698 // "continues humongous" first; in fact we'll do them
2699 // first. The order is important. In on case, calling the
2700 // closure on the "starts humongous" region might de-allocate
2701 // and clear all its "continues humongous" regions and, as a
2702 // result, we might end up processing them twice. So, we'll do
2703 // them first (notice: most closures will ignore them anyway) and
2704 // then we'll do the "starts humongous" region.
2705 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2706 HeapRegion* chr = region_at(ch_index);
2707
2708 // if the region has already been claimed or it's not
2709 // "continues humongous" we're done
2710 if (chr->claim_value() == claim_value ||
2711 !chr->continuesHumongous()) {
2712 break;
2713 }
2714
2715 // No one should have claimed it directly. We can given
2716 // that we claimed its "starts humongous" region.
2717 assert(chr->claim_value() != claim_value, "sanity");
2718 assert(chr->humongous_start_region() == r, "sanity");
2719
2720 if (chr->claimHeapRegion(claim_value)) {
2721 // we should always be able to claim it; no one else should
2722 // be trying to claim this region
2723
2724 bool res2 = cl->doHeapRegion(chr);
2725 assert(!res2, "Should not abort");
2726
2727 // Right now, this holds (i.e., no closure that actually
2728 // does something with "continues humongous" regions
2729 // clears them). We might have to weaken it in the future,
2730 // but let's leave these two asserts here for extra safety.
2731 assert(chr->continuesHumongous(), "should still be the case");
2732 assert(chr->humongous_start_region() == r, "sanity");
2733 } else {
2734 guarantee(false, "we should not reach here");
2735 }
2736 }
2737 }
2738
2739 assert(!r->continuesHumongous(), "sanity");
2740 bool res = cl->doHeapRegion(r);
2741 assert(!res, "Should not abort");
2742 }
2743 }
2744 }
2745
2746 class ResetClaimValuesClosure: public HeapRegionClosure {
2747 public:
2748 bool doHeapRegion(HeapRegion* r) {
2749 r->set_claim_value(HeapRegion::InitialClaimValue);
2750 return false;
2751 }
2752 };
2753
2754 void G1CollectedHeap::reset_heap_region_claim_values() {
2755 ResetClaimValuesClosure blk;
2756 heap_region_iterate(&blk);
2757 }
2758
2759 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2760 ResetClaimValuesClosure blk;
2761 collection_set_iterate(&blk);
2762 }
2763
2764 #ifdef ASSERT
2765 // This checks whether all regions in the heap have the correct claim
2766 // value. I also piggy-backed on this a check to ensure that the
2767 // humongous_start_region() information on "continues humongous"
2768 // regions is correct.
2769
2770 class CheckClaimValuesClosure : public HeapRegionClosure {
2771 private:
2772 jint _claim_value;
2773 uint _failures;
2774 HeapRegion* _sh_region;
2775
2776 public:
2777 CheckClaimValuesClosure(jint claim_value) :
2778 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2779 bool doHeapRegion(HeapRegion* r) {
2780 if (r->claim_value() != _claim_value) {
2781 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2782 "claim value = %d, should be %d",
2783 HR_FORMAT_PARAMS(r),
2784 r->claim_value(), _claim_value);
2785 ++_failures;
2786 }
2787 if (!r->isHumongous()) {
2788 _sh_region = NULL;
2789 } else if (r->startsHumongous()) {
2790 _sh_region = r;
2791 } else if (r->continuesHumongous()) {
2792 if (r->humongous_start_region() != _sh_region) {
2793 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2794 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2795 HR_FORMAT_PARAMS(r),
2796 r->humongous_start_region(),
2797 _sh_region);
2798 ++_failures;
2799 }
2800 }
2801 return false;
2802 }
2803 uint failures() { return _failures; }
2804 };
2805
2806 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2807 CheckClaimValuesClosure cl(claim_value);
2808 heap_region_iterate(&cl);
2809 return cl.failures() == 0;
2810 }
2811
2812 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2813 private:
2814 jint _claim_value;
2815 uint _failures;
2816
2817 public:
2818 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2819 _claim_value(claim_value), _failures(0) { }
2820
2821 uint failures() { return _failures; }
2822
2823 bool doHeapRegion(HeapRegion* hr) {
2824 assert(hr->in_collection_set(), "how?");
2825 assert(!hr->isHumongous(), "H-region in CSet");
2826 if (hr->claim_value() != _claim_value) {
2827 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2828 "claim value = %d, should be %d",
2829 HR_FORMAT_PARAMS(hr),
2830 hr->claim_value(), _claim_value);
2831 _failures += 1;
2832 }
2833 return false;
2834 }
2835 };
2836
2837 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2838 CheckClaimValuesInCSetHRClosure cl(claim_value);
2839 collection_set_iterate(&cl);
2840 return cl.failures() == 0;
2841 }
2842 #endif // ASSERT
2843
2844 // Clear the cached CSet starting regions and (more importantly)
2845 // the time stamps. Called when we reset the GC time stamp.
2846 void G1CollectedHeap::clear_cset_start_regions() {
2847 assert(_worker_cset_start_region != NULL, "sanity");
2848 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2849
2850 int n_queues = MAX2((int)ParallelGCThreads, 1);
2851 for (int i = 0; i < n_queues; i++) {
2852 _worker_cset_start_region[i] = NULL;
2853 _worker_cset_start_region_time_stamp[i] = 0;
2854 }
2855 }
2856
2857 // Given the id of a worker, obtain or calculate a suitable
2858 // starting region for iterating over the current collection set.
2859 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2860 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2861
2862 HeapRegion* result = NULL;
2863 unsigned gc_time_stamp = get_gc_time_stamp();
2864
2865 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2866 // Cached starting region for current worker was set
2867 // during the current pause - so it's valid.
2868 // Note: the cached starting heap region may be NULL
2869 // (when the collection set is empty).
2870 result = _worker_cset_start_region[worker_i];
2871 assert(result == NULL || result->in_collection_set(), "sanity");
2872 return result;
2873 }
2874
2875 // The cached entry was not valid so let's calculate
2876 // a suitable starting heap region for this worker.
2877
2878 // We want the parallel threads to start their collection
2879 // set iteration at different collection set regions to
2880 // avoid contention.
2881 // If we have:
2882 // n collection set regions
2883 // p threads
2884 // Then thread t will start at region floor ((t * n) / p)
2885
2886 result = g1_policy()->collection_set();
2887 if (G1CollectedHeap::use_parallel_gc_threads()) {
2888 uint cs_size = g1_policy()->cset_region_length();
2889 uint active_workers = workers()->active_workers();
2890 assert(UseDynamicNumberOfGCThreads ||
2891 active_workers == workers()->total_workers(),
2892 "Unless dynamic should use total workers");
2893
2894 uint end_ind = (cs_size * worker_i) / active_workers;
2895 uint start_ind = 0;
2896
2897 if (worker_i > 0 &&
2898 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2899 // Previous workers starting region is valid
2900 // so let's iterate from there
2901 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2902 result = _worker_cset_start_region[worker_i - 1];
2903 }
2904
2905 for (uint i = start_ind; i < end_ind; i++) {
2906 result = result->next_in_collection_set();
2907 }
2908 }
2909
2910 // Note: the calculated starting heap region may be NULL
2911 // (when the collection set is empty).
2912 assert(result == NULL || result->in_collection_set(), "sanity");
2913 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2914 "should be updated only once per pause");
2915 _worker_cset_start_region[worker_i] = result;
2916 OrderAccess::storestore();
2917 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2918 return result;
2919 }
2920
2921 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2922 uint no_of_par_workers) {
2923 uint worker_num =
2924 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2925 assert(UseDynamicNumberOfGCThreads ||
2926 no_of_par_workers == workers()->total_workers(),
2927 "Non dynamic should use fixed number of workers");
2928 const uint start_index = n_regions() * worker_i / worker_num;
2929 return region_at(start_index);
2930 }
2931
2932 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2933 HeapRegion* r = g1_policy()->collection_set();
2934 while (r != NULL) {
2935 HeapRegion* next = r->next_in_collection_set();
2936 if (cl->doHeapRegion(r)) {
2937 cl->incomplete();
2938 return;
2939 }
2940 r = next;
2941 }
2942 }
2943
2944 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2945 HeapRegionClosure *cl) {
2946 if (r == NULL) {
2947 // The CSet is empty so there's nothing to do.
2948 return;
2949 }
2950
2951 assert(r->in_collection_set(),
2952 "Start region must be a member of the collection set.");
2953 HeapRegion* cur = r;
2954 while (cur != NULL) {
2955 HeapRegion* next = cur->next_in_collection_set();
2956 if (cl->doHeapRegion(cur) && false) {
2957 cl->incomplete();
2958 return;
2959 }
2960 cur = next;
2961 }
2962 cur = g1_policy()->collection_set();
2963 while (cur != r) {
2964 HeapRegion* next = cur->next_in_collection_set();
2965 if (cl->doHeapRegion(cur) && false) {
2966 cl->incomplete();
2967 return;
2968 }
2969 cur = next;
2970 }
2971 }
2972
2973 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2974 return n_regions() > 0 ? region_at(0) : NULL;
2975 }
2976
2977
2978 Space* G1CollectedHeap::space_containing(const void* addr) const {
2979 return heap_region_containing(addr);
2980 }
2981
2982 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2983 Space* sp = space_containing(addr);
2984 return sp->block_start(addr);
2985 }
2986
2987 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2988 Space* sp = space_containing(addr);
2989 return sp->block_size(addr);
2990 }
2991
2992 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2993 Space* sp = space_containing(addr);
2994 return sp->block_is_obj(addr);
2995 }
2996
2997 bool G1CollectedHeap::supports_tlab_allocation() const {
2998 return true;
2999 }
3000
3001 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3002 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
3003 }
3004
3005 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3006 return young_list()->eden_used_bytes();
3007 }
3008
3009 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3010 // must be smaller than the humongous object limit.
3011 size_t G1CollectedHeap::max_tlab_size() const {
3012 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3013 }
3014
3015 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3016 // Return the remaining space in the cur alloc region, but not less than
3017 // the min TLAB size.
3018
3019 // Also, this value can be at most the humongous object threshold,
3020 // since we can't allow tlabs to grow big enough to accommodate
3021 // humongous objects.
3022
3023 HeapRegion* hr = _mutator_alloc_region.get();
3024 size_t max_tlab = max_tlab_size() * wordSize;
3025 if (hr == NULL) {
3026 return max_tlab;
3027 } else {
3028 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3029 }
3030 }
3031
3032 size_t G1CollectedHeap::max_capacity() const {
3033 return _g1_reserved.byte_size();
3034 }
3035
3036 jlong G1CollectedHeap::millis_since_last_gc() {
3037 // assert(false, "NYI");
3038 return 0;
3039 }
3040
3041 void G1CollectedHeap::prepare_for_verify() {
3042 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3043 ensure_parsability(false);
3044 }
3045 g1_rem_set()->prepare_for_verify();
3046 }
3047
3048 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3049 VerifyOption vo) {
3050 switch (vo) {
3051 case VerifyOption_G1UsePrevMarking:
3052 return hr->obj_allocated_since_prev_marking(obj);
3053 case VerifyOption_G1UseNextMarking:
3054 return hr->obj_allocated_since_next_marking(obj);
3055 case VerifyOption_G1UseMarkWord:
3056 return false;
3057 default:
3058 ShouldNotReachHere();
3059 }
3060 return false; // keep some compilers happy
3061 }
3062
3063 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3064 switch (vo) {
3065 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3066 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3067 case VerifyOption_G1UseMarkWord: return NULL;
3068 default: ShouldNotReachHere();
3069 }
3070 return NULL; // keep some compilers happy
3071 }
3072
3073 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3074 switch (vo) {
3075 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3076 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3077 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3078 default: ShouldNotReachHere();
3079 }
3080 return false; // keep some compilers happy
3081 }
3082
3083 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3084 switch (vo) {
3085 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3086 case VerifyOption_G1UseNextMarking: return "NTAMS";
3087 case VerifyOption_G1UseMarkWord: return "NONE";
3088 default: ShouldNotReachHere();
3089 }
3090 return NULL; // keep some compilers happy
3091 }
3092
3093 class VerifyRootsClosure: public OopClosure {
3094 private:
3095 G1CollectedHeap* _g1h;
3096 VerifyOption _vo;
3097 bool _failures;
3098 public:
3099 // _vo == UsePrevMarking -> use "prev" marking information,
3100 // _vo == UseNextMarking -> use "next" marking information,
3101 // _vo == UseMarkWord -> use mark word from object header.
3102 VerifyRootsClosure(VerifyOption vo) :
3103 _g1h(G1CollectedHeap::heap()),
3104 _vo(vo),
3105 _failures(false) { }
3106
3107 bool failures() { return _failures; }
3108
3109 template <class T> void do_oop_nv(T* p) {
3110 T heap_oop = oopDesc::load_heap_oop(p);
3111 if (!oopDesc::is_null(heap_oop)) {
3112 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3113 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3114 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3115 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3116 if (_vo == VerifyOption_G1UseMarkWord) {
3117 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3118 }
3119 obj->print_on(gclog_or_tty);
3120 _failures = true;
3121 }
3122 }
3123 }
3124
3125 void do_oop(oop* p) { do_oop_nv(p); }
3126 void do_oop(narrowOop* p) { do_oop_nv(p); }
3127 };
3128
3129 class G1VerifyCodeRootOopClosure: public OopClosure {
3130 G1CollectedHeap* _g1h;
3131 OopClosure* _root_cl;
3132 nmethod* _nm;
3133 VerifyOption _vo;
3134 bool _failures;
3135
3136 template <class T> void do_oop_work(T* p) {
3137 // First verify that this root is live
3138 _root_cl->do_oop(p);
3139
3140 if (!G1VerifyHeapRegionCodeRoots) {
3141 // We're not verifying the code roots attached to heap region.
3142 return;
3143 }
3144
3145 // Don't check the code roots during marking verification in a full GC
3146 if (_vo == VerifyOption_G1UseMarkWord) {
3147 return;
3148 }
3149
3150 // Now verify that the current nmethod (which contains p) is
3151 // in the code root list of the heap region containing the
3152 // object referenced by p.
3153
3154 T heap_oop = oopDesc::load_heap_oop(p);
3155 if (!oopDesc::is_null(heap_oop)) {
3156 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3157
3158 // Now fetch the region containing the object
3159 HeapRegion* hr = _g1h->heap_region_containing(obj);
3160 HeapRegionRemSet* hrrs = hr->rem_set();
3161 // Verify that the strong code root list for this region
3162 // contains the nmethod
3163 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3164 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3165 "from nmethod "PTR_FORMAT" not in strong "
3166 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3167 p, _nm, hr->bottom(), hr->end());
3168 _failures = true;
3169 }
3170 }
3171 }
3172
3173 public:
3174 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3175 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3176
3177 void do_oop(oop* p) { do_oop_work(p); }
3178 void do_oop(narrowOop* p) { do_oop_work(p); }
3179
3180 void set_nmethod(nmethod* nm) { _nm = nm; }
3181 bool failures() { return _failures; }
3182 };
3183
3184 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3185 G1VerifyCodeRootOopClosure* _oop_cl;
3186
3187 public:
3188 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3189 _oop_cl(oop_cl) {}
3190
3191 void do_code_blob(CodeBlob* cb) {
3192 nmethod* nm = cb->as_nmethod_or_null();
3193 if (nm != NULL) {
3194 _oop_cl->set_nmethod(nm);
3195 nm->oops_do(_oop_cl);
3196 }
3197 }
3198 };
3199
3200 class YoungRefCounterClosure : public OopClosure {
3201 G1CollectedHeap* _g1h;
3202 int _count;
3203 public:
3204 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3205 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3206 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3207
3208 int count() { return _count; }
3209 void reset_count() { _count = 0; };
3210 };
3211
3212 class VerifyKlassClosure: public KlassClosure {
3213 YoungRefCounterClosure _young_ref_counter_closure;
3214 OopClosure *_oop_closure;
3215 public:
3216 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3217 void do_klass(Klass* k) {
3218 k->oops_do(_oop_closure);
3219
3220 _young_ref_counter_closure.reset_count();
3221 k->oops_do(&_young_ref_counter_closure);
3222 if (_young_ref_counter_closure.count() > 0) {
3223 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3224 }
3225 }
3226 };
3227
3228 class VerifyLivenessOopClosure: public OopClosure {
3229 G1CollectedHeap* _g1h;
3230 VerifyOption _vo;
3231 public:
3232 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3233 _g1h(g1h), _vo(vo)
3234 { }
3235 void do_oop(narrowOop *p) { do_oop_work(p); }
3236 void do_oop( oop *p) { do_oop_work(p); }
3237
3238 template <class T> void do_oop_work(T *p) {
3239 oop obj = oopDesc::load_decode_heap_oop(p);
3240 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3241 "Dead object referenced by a not dead object");
3242 }
3243 };
3244
3245 class VerifyObjsInRegionClosure: public ObjectClosure {
3246 private:
3247 G1CollectedHeap* _g1h;
3248 size_t _live_bytes;
3249 HeapRegion *_hr;
3250 VerifyOption _vo;
3251 public:
3252 // _vo == UsePrevMarking -> use "prev" marking information,
3253 // _vo == UseNextMarking -> use "next" marking information,
3254 // _vo == UseMarkWord -> use mark word from object header.
3255 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3256 : _live_bytes(0), _hr(hr), _vo(vo) {
3257 _g1h = G1CollectedHeap::heap();
3258 }
3259 void do_object(oop o) {
3260 VerifyLivenessOopClosure isLive(_g1h, _vo);
3261 assert(o != NULL, "Huh?");
3262 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3263 // If the object is alive according to the mark word,
3264 // then verify that the marking information agrees.
3265 // Note we can't verify the contra-positive of the
3266 // above: if the object is dead (according to the mark
3267 // word), it may not be marked, or may have been marked
3268 // but has since became dead, or may have been allocated
3269 // since the last marking.
3270 if (_vo == VerifyOption_G1UseMarkWord) {
3271 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3272 }
3273
3274 o->oop_iterate_no_header(&isLive);
3275 if (!_hr->obj_allocated_since_prev_marking(o)) {
3276 size_t obj_size = o->size(); // Make sure we don't overflow
3277 _live_bytes += (obj_size * HeapWordSize);
3278 }
3279 }
3280 }
3281 size_t live_bytes() { return _live_bytes; }
3282 };
3283
3284 class PrintObjsInRegionClosure : public ObjectClosure {
3285 HeapRegion *_hr;
3286 G1CollectedHeap *_g1;
3287 public:
3288 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3289 _g1 = G1CollectedHeap::heap();
3290 };
3291
3292 void do_object(oop o) {
3293 if (o != NULL) {
3294 HeapWord *start = (HeapWord *) o;
3295 size_t word_sz = o->size();
3296 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3297 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3298 (void*) o, word_sz,
3299 _g1->isMarkedPrev(o),
3300 _g1->isMarkedNext(o),
3301 _hr->obj_allocated_since_prev_marking(o));
3302 HeapWord *end = start + word_sz;
3303 HeapWord *cur;
3304 int *val;
3305 for (cur = start; cur < end; cur++) {
3306 val = (int *) cur;
3307 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3308 }
3309 }
3310 }
3311 };
3312
3313 class VerifyRegionClosure: public HeapRegionClosure {
3314 private:
3315 bool _par;
3316 VerifyOption _vo;
3317 bool _failures;
3318 public:
3319 // _vo == UsePrevMarking -> use "prev" marking information,
3320 // _vo == UseNextMarking -> use "next" marking information,
3321 // _vo == UseMarkWord -> use mark word from object header.
3322 VerifyRegionClosure(bool par, VerifyOption vo)
3323 : _par(par),
3324 _vo(vo),
3325 _failures(false) {}
3326
3327 bool failures() {
3328 return _failures;
3329 }
3330
3331 bool doHeapRegion(HeapRegion* r) {
3332 if (!r->continuesHumongous()) {
3333 bool failures = false;
3334 r->verify(_vo, &failures);
3335 if (failures) {
3336 _failures = true;
3337 } else {
3338 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3339 r->object_iterate(¬_dead_yet_cl);
3340 if (_vo != VerifyOption_G1UseNextMarking) {
3341 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3342 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3343 "max_live_bytes "SIZE_FORMAT" "
3344 "< calculated "SIZE_FORMAT,
3345 r->bottom(), r->end(),
3346 r->max_live_bytes(),
3347 not_dead_yet_cl.live_bytes());
3348 _failures = true;
3349 }
3350 } else {
3351 // When vo == UseNextMarking we cannot currently do a sanity
3352 // check on the live bytes as the calculation has not been
3353 // finalized yet.
3354 }
3355 }
3356 }
3357 return false; // stop the region iteration if we hit a failure
3358 }
3359 };
3360
3361 // This is the task used for parallel verification of the heap regions
3362
3363 class G1ParVerifyTask: public AbstractGangTask {
3364 private:
3365 G1CollectedHeap* _g1h;
3366 VerifyOption _vo;
3367 bool _failures;
3368
3369 public:
3370 // _vo == UsePrevMarking -> use "prev" marking information,
3371 // _vo == UseNextMarking -> use "next" marking information,
3372 // _vo == UseMarkWord -> use mark word from object header.
3373 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3374 AbstractGangTask("Parallel verify task"),
3375 _g1h(g1h),
3376 _vo(vo),
3377 _failures(false) { }
3378
3379 bool failures() {
3380 return _failures;
3381 }
3382
3383 void work(uint worker_id) {
3384 HandleMark hm;
3385 VerifyRegionClosure blk(true, _vo);
3386 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3387 _g1h->workers()->active_workers(),
3388 HeapRegion::ParVerifyClaimValue);
3389 if (blk.failures()) {
3390 _failures = true;
3391 }
3392 }
3393 };
3394
3395 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3396 if (SafepointSynchronize::is_at_safepoint()) {
3397 assert(Thread::current()->is_VM_thread(),
3398 "Expected to be executed serially by the VM thread at this point");
3399
3400 if (!silent) { gclog_or_tty->print("Roots "); }
3401 VerifyRootsClosure rootsCl(vo);
3402 VerifyKlassClosure klassCl(this, &rootsCl);
3403
3404 // We apply the relevant closures to all the oops in the
3405 // system dictionary, class loader data graph and the string table.
3406 // Don't verify the code cache here, since it's verified below.
3407 const int so = SO_AllClasses | SO_Strings;
3408
3409 // Need cleared claim bits for the strong roots processing
3410 ClassLoaderDataGraph::clear_claimed_marks();
3411
3412 process_strong_roots(true, // activate StrongRootsScope
3413 ScanningOption(so), // roots scanning options
3414 &rootsCl,
3415 &klassCl
3416 );
3417
3418 // Verify the nmethods in the code cache.
3419 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3420 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3421 CodeCache::blobs_do(&blobsCl);
3422
3423 bool failures = rootsCl.failures() || codeRootsCl.failures();
3424
3425 if (vo != VerifyOption_G1UseMarkWord) {
3426 // If we're verifying during a full GC then the region sets
3427 // will have been torn down at the start of the GC. Therefore
3428 // verifying the region sets will fail. So we only verify
3429 // the region sets when not in a full GC.
3430 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3431 verify_region_sets();
3432 }
3433
3434 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3435 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3436 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3437 "sanity check");
3438
3439 G1ParVerifyTask task(this, vo);
3440 assert(UseDynamicNumberOfGCThreads ||
3441 workers()->active_workers() == workers()->total_workers(),
3442 "If not dynamic should be using all the workers");
3443 int n_workers = workers()->active_workers();
3444 set_par_threads(n_workers);
3445 workers()->run_task(&task);
3446 set_par_threads(0);
3447 if (task.failures()) {
3448 failures = true;
3449 }
3450
3451 // Checks that the expected amount of parallel work was done.
3452 // The implication is that n_workers is > 0.
3453 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3454 "sanity check");
3455
3456 reset_heap_region_claim_values();
3457
3458 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3459 "sanity check");
3460 } else {
3461 VerifyRegionClosure blk(false, vo);
3462 heap_region_iterate(&blk);
3463 if (blk.failures()) {
3464 failures = true;
3465 }
3466 }
3467 if (!silent) gclog_or_tty->print("RemSet ");
3468 rem_set()->verify();
3469
3470 if (G1StringDedup::is_enabled()) {
3471 if (!silent) gclog_or_tty->print("StrDedup ");
3472 G1StringDedup::verify();
3473 }
3474
3475 if (failures) {
3476 gclog_or_tty->print_cr("Heap:");
3477 // It helps to have the per-region information in the output to
3478 // help us track down what went wrong. This is why we call
3479 // print_extended_on() instead of print_on().
3480 print_extended_on(gclog_or_tty);
3481 gclog_or_tty->cr();
3482 #ifndef PRODUCT
3483 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3484 concurrent_mark()->print_reachable("at-verification-failure",
3485 vo, false /* all */);
3486 }
3487 #endif
3488 gclog_or_tty->flush();
3489 }
3490 guarantee(!failures, "there should not have been any failures");
3491 } else {
3492 if (!silent) {
3493 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3494 if (G1StringDedup::is_enabled()) {
3495 gclog_or_tty->print(", StrDedup");
3496 }
3497 gclog_or_tty->print(") ");
3498 }
3499 }
3500 }
3501
3502 void G1CollectedHeap::verify(bool silent) {
3503 verify(silent, VerifyOption_G1UsePrevMarking);
3504 }
3505
3506 double G1CollectedHeap::verify(bool guard, const char* msg) {
3507 double verify_time_ms = 0.0;
3508
3509 if (guard && total_collections() >= VerifyGCStartAt) {
3510 double verify_start = os::elapsedTime();
3511 HandleMark hm; // Discard invalid handles created during verification
3512 prepare_for_verify();
3513 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3514 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3515 }
3516
3517 return verify_time_ms;
3518 }
3519
3520 void G1CollectedHeap::verify_before_gc() {
3521 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3522 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3523 }
3524
3525 void G1CollectedHeap::verify_after_gc() {
3526 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3527 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3528 }
3529
3530 class PrintRegionClosure: public HeapRegionClosure {
3531 outputStream* _st;
3532 public:
3533 PrintRegionClosure(outputStream* st) : _st(st) {}
3534 bool doHeapRegion(HeapRegion* r) {
3535 r->print_on(_st);
3536 return false;
3537 }
3538 };
3539
3540 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3541 const HeapRegion* hr,
3542 const VerifyOption vo) const {
3543 switch (vo) {
3544 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3545 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3546 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3547 default: ShouldNotReachHere();
3548 }
3549 return false; // keep some compilers happy
3550 }
3551
3552 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3553 const VerifyOption vo) const {
3554 switch (vo) {
3555 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3556 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3557 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3558 default: ShouldNotReachHere();
3559 }
3560 return false; // keep some compilers happy
3561 }
3562
3563 void G1CollectedHeap::print_on(outputStream* st) const {
3564 st->print(" %-20s", "garbage-first heap");
3565 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3566 capacity()/K, used_unlocked()/K);
3567 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3568 _g1_storage.low_boundary(),
3569 _g1_storage.high(),
3570 _g1_storage.high_boundary());
3571 st->cr();
3572 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3573 uint young_regions = _young_list->length();
3574 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3575 (size_t) young_regions * HeapRegion::GrainBytes / K);
3576 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3577 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3578 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3579 st->cr();
3580 MetaspaceAux::print_on(st);
3581 }
3582
3583 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3584 print_on(st);
3585
3586 // Print the per-region information.
3587 st->cr();
3588 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3589 "HS=humongous(starts), HC=humongous(continues), "
3590 "CS=collection set, F=free, TS=gc time stamp, "
3591 "PTAMS=previous top-at-mark-start, "
3592 "NTAMS=next top-at-mark-start)");
3593 PrintRegionClosure blk(st);
3594 heap_region_iterate(&blk);
3595 }
3596
3597 void G1CollectedHeap::print_on_error(outputStream* st) const {
3598 this->CollectedHeap::print_on_error(st);
3599
3600 if (_cm != NULL) {
3601 st->cr();
3602 _cm->print_on_error(st);
3603 }
3604 }
3605
3606 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3607 if (G1CollectedHeap::use_parallel_gc_threads()) {
3608 workers()->print_worker_threads_on(st);
3609 }
3610 _cmThread->print_on(st);
3611 st->cr();
3612 _cm->print_worker_threads_on(st);
3613 _cg1r->print_worker_threads_on(st);
3614 if (G1StringDedup::is_enabled()) {
3615 G1StringDedup::print_worker_threads_on(st);
3616 }
3617 }
3618
3619 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3620 if (G1CollectedHeap::use_parallel_gc_threads()) {
3621 workers()->threads_do(tc);
3622 }
3623 tc->do_thread(_cmThread);
3624 _cg1r->threads_do(tc);
3625 if (G1StringDedup::is_enabled()) {
3626 G1StringDedup::threads_do(tc);
3627 }
3628 }
3629
3630 void G1CollectedHeap::print_tracing_info() const {
3631 // We'll overload this to mean "trace GC pause statistics."
3632 if (TraceGen0Time || TraceGen1Time) {
3633 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3634 // to that.
3635 g1_policy()->print_tracing_info();
3636 }
3637 if (G1SummarizeRSetStats) {
3638 g1_rem_set()->print_summary_info();
3639 }
3640 if (G1SummarizeConcMark) {
3641 concurrent_mark()->print_summary_info();
3642 }
3643 g1_policy()->print_yg_surv_rate_info();
3644 SpecializationStats::print();
3645 }
3646
3647 #ifndef PRODUCT
3648 // Helpful for debugging RSet issues.
3649
3650 class PrintRSetsClosure : public HeapRegionClosure {
3651 private:
3652 const char* _msg;
3653 size_t _occupied_sum;
3654
3655 public:
3656 bool doHeapRegion(HeapRegion* r) {
3657 HeapRegionRemSet* hrrs = r->rem_set();
3658 size_t occupied = hrrs->occupied();
3659 _occupied_sum += occupied;
3660
3661 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3662 HR_FORMAT_PARAMS(r));
3663 if (occupied == 0) {
3664 gclog_or_tty->print_cr(" RSet is empty");
3665 } else {
3666 hrrs->print();
3667 }
3668 gclog_or_tty->print_cr("----------");
3669 return false;
3670 }
3671
3672 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3673 gclog_or_tty->cr();
3674 gclog_or_tty->print_cr("========================================");
3675 gclog_or_tty->print_cr("%s", msg);
3676 gclog_or_tty->cr();
3677 }
3678
3679 ~PrintRSetsClosure() {
3680 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3681 gclog_or_tty->print_cr("========================================");
3682 gclog_or_tty->cr();
3683 }
3684 };
3685
3686 void G1CollectedHeap::print_cset_rsets() {
3687 PrintRSetsClosure cl("Printing CSet RSets");
3688 collection_set_iterate(&cl);
3689 }
3690
3691 void G1CollectedHeap::print_all_rsets() {
3692 PrintRSetsClosure cl("Printing All RSets");;
3693 heap_region_iterate(&cl);
3694 }
3695 #endif // PRODUCT
3696
3697 G1CollectedHeap* G1CollectedHeap::heap() {
3698 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3699 "not a garbage-first heap");
3700 return _g1h;
3701 }
3702
3703 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3704 // always_do_update_barrier = false;
3705 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3706 // Fill TLAB's and such
3707 accumulate_statistics_all_tlabs();
3708 ensure_parsability(true);
3709
3710 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3711 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3712 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3713 }
3714 }
3715
3716 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3717
3718 if (G1SummarizeRSetStats &&
3719 (G1SummarizeRSetStatsPeriod > 0) &&
3720 // we are at the end of the GC. Total collections has already been increased.
3721 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3722 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3723 }
3724
3725 // FIXME: what is this about?
3726 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3727 // is set.
3728 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3729 "derived pointer present"));
3730 // always_do_update_barrier = true;
3731
3732 resize_all_tlabs();
3733
3734 // We have just completed a GC. Update the soft reference
3735 // policy with the new heap occupancy
3736 Universe::update_heap_info_at_gc();
3737 }
3738
3739 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3740 unsigned int gc_count_before,
3741 bool* succeeded,
3742 GCCause::Cause gc_cause) {
3743 assert_heap_not_locked_and_not_at_safepoint();
3744 g1_policy()->record_stop_world_start();
3745 VM_G1IncCollectionPause op(gc_count_before,
3746 word_size,
3747 false, /* should_initiate_conc_mark */
3748 g1_policy()->max_pause_time_ms(),
3749 gc_cause);
3750 VMThread::execute(&op);
3751
3752 HeapWord* result = op.result();
3753 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3754 assert(result == NULL || ret_succeeded,
3755 "the result should be NULL if the VM did not succeed");
3756 *succeeded = ret_succeeded;
3757
3758 assert_heap_not_locked();
3759 return result;
3760 }
3761
3762 void
3763 G1CollectedHeap::doConcurrentMark() {
3764 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3765 if (!_cmThread->in_progress()) {
3766 _cmThread->set_started();
3767 CGC_lock->notify();
3768 }
3769 }
3770
3771 size_t G1CollectedHeap::pending_card_num() {
3772 size_t extra_cards = 0;
3773 JavaThread *curr = Threads::first();
3774 while (curr != NULL) {
3775 DirtyCardQueue& dcq = curr->dirty_card_queue();
3776 extra_cards += dcq.size();
3777 curr = curr->next();
3778 }
3779 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3780 size_t buffer_size = dcqs.buffer_size();
3781 size_t buffer_num = dcqs.completed_buffers_num();
3782
3783 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3784 // in bytes - not the number of 'entries'. We need to convert
3785 // into a number of cards.
3786 return (buffer_size * buffer_num + extra_cards) / oopSize;
3787 }
3788
3789 size_t G1CollectedHeap::cards_scanned() {
3790 return g1_rem_set()->cardsScanned();
3791 }
3792
3793 void
3794 G1CollectedHeap::setup_surviving_young_words() {
3795 assert(_surviving_young_words == NULL, "pre-condition");
3796 uint array_length = g1_policy()->young_cset_region_length();
3797 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3798 if (_surviving_young_words == NULL) {
3799 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3800 "Not enough space for young surv words summary.");
3801 }
3802 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3803 #ifdef ASSERT
3804 for (uint i = 0; i < array_length; ++i) {
3805 assert( _surviving_young_words[i] == 0, "memset above" );
3806 }
3807 #endif // !ASSERT
3808 }
3809
3810 void
3811 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3812 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3813 uint array_length = g1_policy()->young_cset_region_length();
3814 for (uint i = 0; i < array_length; ++i) {
3815 _surviving_young_words[i] += surv_young_words[i];
3816 }
3817 }
3818
3819 void
3820 G1CollectedHeap::cleanup_surviving_young_words() {
3821 guarantee( _surviving_young_words != NULL, "pre-condition" );
3822 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3823 _surviving_young_words = NULL;
3824 }
3825
3826 #ifdef ASSERT
3827 class VerifyCSetClosure: public HeapRegionClosure {
3828 public:
3829 bool doHeapRegion(HeapRegion* hr) {
3830 // Here we check that the CSet region's RSet is ready for parallel
3831 // iteration. The fields that we'll verify are only manipulated
3832 // when the region is part of a CSet and is collected. Afterwards,
3833 // we reset these fields when we clear the region's RSet (when the
3834 // region is freed) so they are ready when the region is
3835 // re-allocated. The only exception to this is if there's an
3836 // evacuation failure and instead of freeing the region we leave
3837 // it in the heap. In that case, we reset these fields during
3838 // evacuation failure handling.
3839 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3840
3841 // Here's a good place to add any other checks we'd like to
3842 // perform on CSet regions.
3843 return false;
3844 }
3845 };
3846 #endif // ASSERT
3847
3848 #if TASKQUEUE_STATS
3849 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3850 st->print_raw_cr("GC Task Stats");
3851 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3852 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3853 }
3854
3855 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3856 print_taskqueue_stats_hdr(st);
3857
3858 TaskQueueStats totals;
3859 const int n = workers() != NULL ? workers()->total_workers() : 1;
3860 for (int i = 0; i < n; ++i) {
3861 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3862 totals += task_queue(i)->stats;
3863 }
3864 st->print_raw("tot "); totals.print(st); st->cr();
3865
3866 DEBUG_ONLY(totals.verify());
3867 }
3868
3869 void G1CollectedHeap::reset_taskqueue_stats() {
3870 const int n = workers() != NULL ? workers()->total_workers() : 1;
3871 for (int i = 0; i < n; ++i) {
3872 task_queue(i)->stats.reset();
3873 }
3874 }
3875 #endif // TASKQUEUE_STATS
3876
3877 void G1CollectedHeap::log_gc_header() {
3878 if (!G1Log::fine()) {
3879 return;
3880 }
3881
3882 gclog_or_tty->date_stamp(PrintGCDateStamps);
3883 gclog_or_tty->stamp(PrintGCTimeStamps);
3884
3885 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3886 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3887 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3888
3889 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3890 }
3891
3892 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3893 if (!G1Log::fine()) {
3894 return;
3895 }
3896
3897 if (G1Log::finer()) {
3898 if (evacuation_failed()) {
3899 gclog_or_tty->print(" (to-space exhausted)");
3900 }
3901 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3902 g1_policy()->phase_times()->note_gc_end();
3903 g1_policy()->phase_times()->print(pause_time_sec);
3904 g1_policy()->print_detailed_heap_transition();
3905 } else {
3906 if (evacuation_failed()) {
3907 gclog_or_tty->print("--");
3908 }
3909 g1_policy()->print_heap_transition();
3910 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3911 }
3912 gclog_or_tty->flush();
3913 }
3914
3915 bool
3916 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3917 assert_at_safepoint(true /* should_be_vm_thread */);
3918 guarantee(!is_gc_active(), "collection is not reentrant");
3919
3920 if (GC_locker::check_active_before_gc()) {
3921 return false;
3922 }
3923
3924 _gc_timer_stw->register_gc_start();
3925
3926 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3927
3928 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3929 ResourceMark rm;
3930
3931 print_heap_before_gc();
3932 trace_heap_before_gc(_gc_tracer_stw);
3933
3934 verify_region_sets_optional();
3935 verify_dirty_young_regions();
3936
3937 // This call will decide whether this pause is an initial-mark
3938 // pause. If it is, during_initial_mark_pause() will return true
3939 // for the duration of this pause.
3940 g1_policy()->decide_on_conc_mark_initiation();
3941
3942 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3943 assert(!g1_policy()->during_initial_mark_pause() ||
3944 g1_policy()->gcs_are_young(), "sanity");
3945
3946 // We also do not allow mixed GCs during marking.
3947 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3948
3949 // Record whether this pause is an initial mark. When the current
3950 // thread has completed its logging output and it's safe to signal
3951 // the CM thread, the flag's value in the policy has been reset.
3952 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3953
3954 // Inner scope for scope based logging, timers, and stats collection
3955 {
3956 EvacuationInfo evacuation_info;
3957
3958 if (g1_policy()->during_initial_mark_pause()) {
3959 // We are about to start a marking cycle, so we increment the
3960 // full collection counter.
3961 increment_old_marking_cycles_started();
3962 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3963 }
3964
3965 _gc_tracer_stw->report_yc_type(yc_type());
3966
3967 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3968
3969 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3970 workers()->active_workers() : 1);
3971 double pause_start_sec = os::elapsedTime();
3972 g1_policy()->phase_times()->note_gc_start(active_workers);
3973 log_gc_header();
3974
3975 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3976 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3977
3978 // If the secondary_free_list is not empty, append it to the
3979 // free_list. No need to wait for the cleanup operation to finish;
3980 // the region allocation code will check the secondary_free_list
3981 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3982 // set, skip this step so that the region allocation code has to
3983 // get entries from the secondary_free_list.
3984 if (!G1StressConcRegionFreeing) {
3985 append_secondary_free_list_if_not_empty_with_lock();
3986 }
3987
3988 assert(check_young_list_well_formed(), "young list should be well formed");
3989 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3990 "sanity check");
3991
3992 // Don't dynamically change the number of GC threads this early. A value of
3993 // 0 is used to indicate serial work. When parallel work is done,
3994 // it will be set.
3995
3996 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3997 IsGCActiveMark x;
3998
3999 gc_prologue(false);
4000 increment_total_collections(false /* full gc */);
4001 increment_gc_time_stamp();
4002
4003 verify_before_gc();
4004 check_bitmaps("GC Start");
4005
4006 COMPILER2_PRESENT(DerivedPointerTable::clear());
4007
4008 // Please see comment in g1CollectedHeap.hpp and
4009 // G1CollectedHeap::ref_processing_init() to see how
4010 // reference processing currently works in G1.
4011
4012 // Enable discovery in the STW reference processor
4013 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4014 true /*verify_no_refs*/);
4015
4016 {
4017 // We want to temporarily turn off discovery by the
4018 // CM ref processor, if necessary, and turn it back on
4019 // on again later if we do. Using a scoped
4020 // NoRefDiscovery object will do this.
4021 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4022
4023 // Forget the current alloc region (we might even choose it to be part
4024 // of the collection set!).
4025 release_mutator_alloc_region();
4026
4027 // We should call this after we retire the mutator alloc
4028 // region(s) so that all the ALLOC / RETIRE events are generated
4029 // before the start GC event.
4030 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4031
4032 // This timing is only used by the ergonomics to handle our pause target.
4033 // It is unclear why this should not include the full pause. We will
4034 // investigate this in CR 7178365.
4035 //
4036 // Preserving the old comment here if that helps the investigation:
4037 //
4038 // The elapsed time induced by the start time below deliberately elides
4039 // the possible verification above.
4040 double sample_start_time_sec = os::elapsedTime();
4041
4042 #if YOUNG_LIST_VERBOSE
4043 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4044 _young_list->print();
4045 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4046 #endif // YOUNG_LIST_VERBOSE
4047
4048 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4049
4050 double scan_wait_start = os::elapsedTime();
4051 // We have to wait until the CM threads finish scanning the
4052 // root regions as it's the only way to ensure that all the
4053 // objects on them have been correctly scanned before we start
4054 // moving them during the GC.
4055 bool waited = _cm->root_regions()->wait_until_scan_finished();
4056 double wait_time_ms = 0.0;
4057 if (waited) {
4058 double scan_wait_end = os::elapsedTime();
4059 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4060 }
4061 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4062
4063 #if YOUNG_LIST_VERBOSE
4064 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4065 _young_list->print();
4066 #endif // YOUNG_LIST_VERBOSE
4067
4068 if (g1_policy()->during_initial_mark_pause()) {
4069 concurrent_mark()->checkpointRootsInitialPre();
4070 }
4071
4072 #if YOUNG_LIST_VERBOSE
4073 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4074 _young_list->print();
4075 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4076 #endif // YOUNG_LIST_VERBOSE
4077
4078 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4079
4080 _cm->note_start_of_gc();
4081 // We should not verify the per-thread SATB buffers given that
4082 // we have not filtered them yet (we'll do so during the
4083 // GC). We also call this after finalize_cset() to
4084 // ensure that the CSet has been finalized.
4085 _cm->verify_no_cset_oops(true /* verify_stacks */,
4086 true /* verify_enqueued_buffers */,
4087 false /* verify_thread_buffers */,
4088 true /* verify_fingers */);
4089
4090 if (_hr_printer.is_active()) {
4091 HeapRegion* hr = g1_policy()->collection_set();
4092 while (hr != NULL) {
4093 G1HRPrinter::RegionType type;
4094 if (!hr->is_young()) {
4095 type = G1HRPrinter::Old;
4096 } else if (hr->is_survivor()) {
4097 type = G1HRPrinter::Survivor;
4098 } else {
4099 type = G1HRPrinter::Eden;
4100 }
4101 _hr_printer.cset(hr);
4102 hr = hr->next_in_collection_set();
4103 }
4104 }
4105
4106 #ifdef ASSERT
4107 VerifyCSetClosure cl;
4108 collection_set_iterate(&cl);
4109 #endif // ASSERT
4110
4111 setup_surviving_young_words();
4112
4113 // Initialize the GC alloc regions.
4114 init_gc_alloc_regions(evacuation_info);
4115
4116 // Actually do the work...
4117 evacuate_collection_set(evacuation_info);
4118
4119 // We do this to mainly verify the per-thread SATB buffers
4120 // (which have been filtered by now) since we didn't verify
4121 // them earlier. No point in re-checking the stacks / enqueued
4122 // buffers given that the CSet has not changed since last time
4123 // we checked.
4124 _cm->verify_no_cset_oops(false /* verify_stacks */,
4125 false /* verify_enqueued_buffers */,
4126 true /* verify_thread_buffers */,
4127 true /* verify_fingers */);
4128
4129 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4130 g1_policy()->clear_collection_set();
4131
4132 cleanup_surviving_young_words();
4133
4134 // Start a new incremental collection set for the next pause.
4135 g1_policy()->start_incremental_cset_building();
4136
4137 clear_cset_fast_test();
4138
4139 _young_list->reset_sampled_info();
4140
4141 // Don't check the whole heap at this point as the
4142 // GC alloc regions from this pause have been tagged
4143 // as survivors and moved on to the survivor list.
4144 // Survivor regions will fail the !is_young() check.
4145 assert(check_young_list_empty(false /* check_heap */),
4146 "young list should be empty");
4147
4148 #if YOUNG_LIST_VERBOSE
4149 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4150 _young_list->print();
4151 #endif // YOUNG_LIST_VERBOSE
4152
4153 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4154 _young_list->first_survivor_region(),
4155 _young_list->last_survivor_region());
4156
4157 _young_list->reset_auxilary_lists();
4158
4159 if (evacuation_failed()) {
4160 _summary_bytes_used = recalculate_used();
4161 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4162 for (uint i = 0; i < n_queues; i++) {
4163 if (_evacuation_failed_info_array[i].has_failed()) {
4164 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4165 }
4166 }
4167 } else {
4168 // The "used" of the the collection set have already been subtracted
4169 // when they were freed. Add in the bytes evacuated.
4170 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4171 }
4172
4173 if (g1_policy()->during_initial_mark_pause()) {
4174 // We have to do this before we notify the CM threads that
4175 // they can start working to make sure that all the
4176 // appropriate initialization is done on the CM object.
4177 concurrent_mark()->checkpointRootsInitialPost();
4178 set_marking_started();
4179 // Note that we don't actually trigger the CM thread at
4180 // this point. We do that later when we're sure that
4181 // the current thread has completed its logging output.
4182 }
4183
4184 allocate_dummy_regions();
4185
4186 #if YOUNG_LIST_VERBOSE
4187 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4188 _young_list->print();
4189 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4190 #endif // YOUNG_LIST_VERBOSE
4191
4192 init_mutator_alloc_region();
4193
4194 {
4195 size_t expand_bytes = g1_policy()->expansion_amount();
4196 if (expand_bytes > 0) {
4197 size_t bytes_before = capacity();
4198 // No need for an ergo verbose message here,
4199 // expansion_amount() does this when it returns a value > 0.
4200 if (!expand(expand_bytes)) {
4201 // We failed to expand the heap so let's verify that
4202 // committed/uncommitted amount match the backing store
4203 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4204 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4205 }
4206 }
4207 }
4208
4209 // We redo the verification but now wrt to the new CSet which
4210 // has just got initialized after the previous CSet was freed.
4211 _cm->verify_no_cset_oops(true /* verify_stacks */,
4212 true /* verify_enqueued_buffers */,
4213 true /* verify_thread_buffers */,
4214 true /* verify_fingers */);
4215 _cm->note_end_of_gc();
4216
4217 // This timing is only used by the ergonomics to handle our pause target.
4218 // It is unclear why this should not include the full pause. We will
4219 // investigate this in CR 7178365.
4220 double sample_end_time_sec = os::elapsedTime();
4221 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4222 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4223
4224 MemoryService::track_memory_usage();
4225
4226 // In prepare_for_verify() below we'll need to scan the deferred
4227 // update buffers to bring the RSets up-to-date if
4228 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4229 // the update buffers we'll probably need to scan cards on the
4230 // regions we just allocated to (i.e., the GC alloc
4231 // regions). However, during the last GC we called
4232 // set_saved_mark() on all the GC alloc regions, so card
4233 // scanning might skip the [saved_mark_word()...top()] area of
4234 // those regions (i.e., the area we allocated objects into
4235 // during the last GC). But it shouldn't. Given that
4236 // saved_mark_word() is conditional on whether the GC time stamp
4237 // on the region is current or not, by incrementing the GC time
4238 // stamp here we invalidate all the GC time stamps on all the
4239 // regions and saved_mark_word() will simply return top() for
4240 // all the regions. This is a nicer way of ensuring this rather
4241 // than iterating over the regions and fixing them. In fact, the
4242 // GC time stamp increment here also ensures that
4243 // saved_mark_word() will return top() between pauses, i.e.,
4244 // during concurrent refinement. So we don't need the
4245 // is_gc_active() check to decided which top to use when
4246 // scanning cards (see CR 7039627).
4247 increment_gc_time_stamp();
4248
4249 verify_after_gc();
4250 check_bitmaps("GC End");
4251
4252 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4253 ref_processor_stw()->verify_no_references_recorded();
4254
4255 // CM reference discovery will be re-enabled if necessary.
4256 }
4257
4258 // We should do this after we potentially expand the heap so
4259 // that all the COMMIT events are generated before the end GC
4260 // event, and after we retire the GC alloc regions so that all
4261 // RETIRE events are generated before the end GC event.
4262 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4263
4264 if (mark_in_progress()) {
4265 concurrent_mark()->update_g1_committed();
4266 }
4267
4268 #ifdef TRACESPINNING
4269 ParallelTaskTerminator::print_termination_counts();
4270 #endif
4271
4272 gc_epilogue(false);
4273 }
4274
4275 // Print the remainder of the GC log output.
4276 log_gc_footer(os::elapsedTime() - pause_start_sec);
4277
4278 // It is not yet to safe to tell the concurrent mark to
4279 // start as we have some optional output below. We don't want the
4280 // output from the concurrent mark thread interfering with this
4281 // logging output either.
4282
4283 _hrs.verify_optional();
4284 verify_region_sets_optional();
4285
4286 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4287 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4288
4289 print_heap_after_gc();
4290 trace_heap_after_gc(_gc_tracer_stw);
4291
4292 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4293 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4294 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4295 // before any GC notifications are raised.
4296 g1mm()->update_sizes();
4297
4298 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4299 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4300 _gc_timer_stw->register_gc_end();
4301 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4302 }
4303 // It should now be safe to tell the concurrent mark thread to start
4304 // without its logging output interfering with the logging output
4305 // that came from the pause.
4306
4307 if (should_start_conc_mark) {
4308 // CAUTION: after the doConcurrentMark() call below,
4309 // the concurrent marking thread(s) could be running
4310 // concurrently with us. Make sure that anything after
4311 // this point does not assume that we are the only GC thread
4312 // running. Note: of course, the actual marking work will
4313 // not start until the safepoint itself is released in
4314 // SuspendibleThreadSet::desynchronize().
4315 doConcurrentMark();
4316 }
4317
4318 return true;
4319 }
4320
4321 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4322 {
4323 size_t gclab_word_size;
4324 switch (purpose) {
4325 case GCAllocForSurvived:
4326 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4327 break;
4328 case GCAllocForTenured:
4329 gclab_word_size = _old_plab_stats.desired_plab_sz();
4330 break;
4331 default:
4332 assert(false, "unknown GCAllocPurpose");
4333 gclab_word_size = _old_plab_stats.desired_plab_sz();
4334 break;
4335 }
4336
4337 // Prevent humongous PLAB sizes for two reasons:
4338 // * PLABs are allocated using a similar paths as oops, but should
4339 // never be in a humongous region
4340 // * Allowing humongous PLABs needlessly churns the region free lists
4341 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4342 }
4343
4344 void G1CollectedHeap::init_mutator_alloc_region() {
4345 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4346 _mutator_alloc_region.init();
4347 }
4348
4349 void G1CollectedHeap::release_mutator_alloc_region() {
4350 _mutator_alloc_region.release();
4351 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4352 }
4353
4354 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4355 assert_at_safepoint(true /* should_be_vm_thread */);
4356
4357 _survivor_gc_alloc_region.init();
4358 _old_gc_alloc_region.init();
4359 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4360 _retained_old_gc_alloc_region = NULL;
4361
4362 // We will discard the current GC alloc region if:
4363 // a) it's in the collection set (it can happen!),
4364 // b) it's already full (no point in using it),
4365 // c) it's empty (this means that it was emptied during
4366 // a cleanup and it should be on the free list now), or
4367 // d) it's humongous (this means that it was emptied
4368 // during a cleanup and was added to the free list, but
4369 // has been subsequently used to allocate a humongous
4370 // object that may be less than the region size).
4371 if (retained_region != NULL &&
4372 !retained_region->in_collection_set() &&
4373 !(retained_region->top() == retained_region->end()) &&
4374 !retained_region->is_empty() &&
4375 !retained_region->isHumongous()) {
4376 retained_region->set_saved_mark();
4377 // The retained region was added to the old region set when it was
4378 // retired. We have to remove it now, since we don't allow regions
4379 // we allocate to in the region sets. We'll re-add it later, when
4380 // it's retired again.
4381 _old_set.remove(retained_region);
4382 bool during_im = g1_policy()->during_initial_mark_pause();
4383 retained_region->note_start_of_copying(during_im);
4384 _old_gc_alloc_region.set(retained_region);
4385 _hr_printer.reuse(retained_region);
4386 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4387 }
4388 }
4389
4390 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4391 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4392 _old_gc_alloc_region.count());
4393 _survivor_gc_alloc_region.release();
4394 // If we have an old GC alloc region to release, we'll save it in
4395 // _retained_old_gc_alloc_region. If we don't
4396 // _retained_old_gc_alloc_region will become NULL. This is what we
4397 // want either way so no reason to check explicitly for either
4398 // condition.
4399 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4400
4401 if (ResizePLAB) {
4402 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4403 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4404 }
4405 }
4406
4407 void G1CollectedHeap::abandon_gc_alloc_regions() {
4408 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4409 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4410 _retained_old_gc_alloc_region = NULL;
4411 }
4412
4413 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4414 _drain_in_progress = false;
4415 set_evac_failure_closure(cl);
4416 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4417 }
4418
4419 void G1CollectedHeap::finalize_for_evac_failure() {
4420 assert(_evac_failure_scan_stack != NULL &&
4421 _evac_failure_scan_stack->length() == 0,
4422 "Postcondition");
4423 assert(!_drain_in_progress, "Postcondition");
4424 delete _evac_failure_scan_stack;
4425 _evac_failure_scan_stack = NULL;
4426 }
4427
4428 void G1CollectedHeap::remove_self_forwarding_pointers() {
4429 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4430
4431 double remove_self_forwards_start = os::elapsedTime();
4432
4433 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4434
4435 if (G1CollectedHeap::use_parallel_gc_threads()) {
4436 set_par_threads();
4437 workers()->run_task(&rsfp_task);
4438 set_par_threads(0);
4439 } else {
4440 rsfp_task.work(0);
4441 }
4442
4443 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4444
4445 // Reset the claim values in the regions in the collection set.
4446 reset_cset_heap_region_claim_values();
4447
4448 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4449
4450 // Now restore saved marks, if any.
4451 assert(_objs_with_preserved_marks.size() ==
4452 _preserved_marks_of_objs.size(), "Both or none.");
4453 while (!_objs_with_preserved_marks.is_empty()) {
4454 oop obj = _objs_with_preserved_marks.pop();
4455 markOop m = _preserved_marks_of_objs.pop();
4456 obj->set_mark(m);
4457 }
4458 _objs_with_preserved_marks.clear(true);
4459 _preserved_marks_of_objs.clear(true);
4460
4461 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4462 }
4463
4464 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4465 _evac_failure_scan_stack->push(obj);
4466 }
4467
4468 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4469 assert(_evac_failure_scan_stack != NULL, "precondition");
4470
4471 while (_evac_failure_scan_stack->length() > 0) {
4472 oop obj = _evac_failure_scan_stack->pop();
4473 _evac_failure_closure->set_region(heap_region_containing(obj));
4474 obj->oop_iterate_backwards(_evac_failure_closure);
4475 }
4476 }
4477
4478 oop
4479 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4480 oop old) {
4481 assert(obj_in_cs(old),
4482 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4483 (HeapWord*) old));
4484 markOop m = old->mark();
4485 oop forward_ptr = old->forward_to_atomic(old);
4486 if (forward_ptr == NULL) {
4487 // Forward-to-self succeeded.
4488 assert(_par_scan_state != NULL, "par scan state");
4489 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4490 uint queue_num = _par_scan_state->queue_num();
4491
4492 _evacuation_failed = true;
4493 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4494 if (_evac_failure_closure != cl) {
4495 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4496 assert(!_drain_in_progress,
4497 "Should only be true while someone holds the lock.");
4498 // Set the global evac-failure closure to the current thread's.
4499 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4500 set_evac_failure_closure(cl);
4501 // Now do the common part.
4502 handle_evacuation_failure_common(old, m);
4503 // Reset to NULL.
4504 set_evac_failure_closure(NULL);
4505 } else {
4506 // The lock is already held, and this is recursive.
4507 assert(_drain_in_progress, "This should only be the recursive case.");
4508 handle_evacuation_failure_common(old, m);
4509 }
4510 return old;
4511 } else {
4512 // Forward-to-self failed. Either someone else managed to allocate
4513 // space for this object (old != forward_ptr) or they beat us in
4514 // self-forwarding it (old == forward_ptr).
4515 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4516 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4517 "should not be in the CSet",
4518 (HeapWord*) old, (HeapWord*) forward_ptr));
4519 return forward_ptr;
4520 }
4521 }
4522
4523 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4524 preserve_mark_if_necessary(old, m);
4525
4526 HeapRegion* r = heap_region_containing(old);
4527 if (!r->evacuation_failed()) {
4528 r->set_evacuation_failed(true);
4529 _hr_printer.evac_failure(r);
4530 }
4531
4532 push_on_evac_failure_scan_stack(old);
4533
4534 if (!_drain_in_progress) {
4535 // prevent recursion in copy_to_survivor_space()
4536 _drain_in_progress = true;
4537 drain_evac_failure_scan_stack();
4538 _drain_in_progress = false;
4539 }
4540 }
4541
4542 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4543 assert(evacuation_failed(), "Oversaving!");
4544 // We want to call the "for_promotion_failure" version only in the
4545 // case of a promotion failure.
4546 if (m->must_be_preserved_for_promotion_failure(obj)) {
4547 _objs_with_preserved_marks.push(obj);
4548 _preserved_marks_of_objs.push(m);
4549 }
4550 }
4551
4552 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4553 size_t word_size) {
4554 if (purpose == GCAllocForSurvived) {
4555 HeapWord* result = survivor_attempt_allocation(word_size);
4556 if (result != NULL) {
4557 return result;
4558 } else {
4559 // Let's try to allocate in the old gen in case we can fit the
4560 // object there.
4561 return old_attempt_allocation(word_size);
4562 }
4563 } else {
4564 assert(purpose == GCAllocForTenured, "sanity");
4565 HeapWord* result = old_attempt_allocation(word_size);
4566 if (result != NULL) {
4567 return result;
4568 } else {
4569 // Let's try to allocate in the survivors in case we can fit the
4570 // object there.
4571 return survivor_attempt_allocation(word_size);
4572 }
4573 }
4574
4575 ShouldNotReachHere();
4576 // Trying to keep some compilers happy.
4577 return NULL;
4578 }
4579
4580 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4581 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4582
4583 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4584 : _g1h(g1h),
4585 _refs(g1h->task_queue(queue_num)),
4586 _dcq(&g1h->dirty_card_queue_set()),
4587 _ct_bs(g1h->g1_barrier_set()),
4588 _g1_rem(g1h->g1_rem_set()),
4589 _hash_seed(17), _queue_num(queue_num),
4590 _term_attempts(0),
4591 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4592 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4593 _age_table(false), _scanner(g1h, this, rp),
4594 _strong_roots_time(0), _term_time(0),
4595 _alloc_buffer_waste(0), _undo_waste(0) {
4596 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4597 // we "sacrifice" entry 0 to keep track of surviving bytes for
4598 // non-young regions (where the age is -1)
4599 // We also add a few elements at the beginning and at the end in
4600 // an attempt to eliminate cache contention
4601 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4602 uint array_length = PADDING_ELEM_NUM +
4603 real_length +
4604 PADDING_ELEM_NUM;
4605 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4606 if (_surviving_young_words_base == NULL)
4607 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4608 "Not enough space for young surv histo.");
4609 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4610 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4611
4612 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4613 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4614
4615 _start = os::elapsedTime();
4616 }
4617
4618 void
4619 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4620 {
4621 st->print_raw_cr("GC Termination Stats");
4622 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4623 " ------waste (KiB)------");
4624 st->print_raw_cr("thr ms ms % ms % attempts"
4625 " total alloc undo");
4626 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4627 " ------- ------- -------");
4628 }
4629
4630 void
4631 G1ParScanThreadState::print_termination_stats(int i,
4632 outputStream* const st) const
4633 {
4634 const double elapsed_ms = elapsed_time() * 1000.0;
4635 const double s_roots_ms = strong_roots_time() * 1000.0;
4636 const double term_ms = term_time() * 1000.0;
4637 st->print_cr("%3d %9.2f %9.2f %6.2f "
4638 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4639 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4640 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4641 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4642 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4643 alloc_buffer_waste() * HeapWordSize / K,
4644 undo_waste() * HeapWordSize / K);
4645 }
4646
4647 #ifdef ASSERT
4648 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4649 assert(ref != NULL, "invariant");
4650 assert(UseCompressedOops, "sanity");
4651 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4652 oop p = oopDesc::load_decode_heap_oop(ref);
4653 assert(_g1h->is_in_g1_reserved(p),
4654 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4655 return true;
4656 }
4657
4658 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4659 assert(ref != NULL, "invariant");
4660 if (has_partial_array_mask(ref)) {
4661 // Must be in the collection set--it's already been copied.
4662 oop p = clear_partial_array_mask(ref);
4663 assert(_g1h->obj_in_cs(p),
4664 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4665 } else {
4666 oop p = oopDesc::load_decode_heap_oop(ref);
4667 assert(_g1h->is_in_g1_reserved(p),
4668 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4669 }
4670 return true;
4671 }
4672
4673 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4674 if (ref.is_narrow()) {
4675 return verify_ref((narrowOop*) ref);
4676 } else {
4677 return verify_ref((oop*) ref);
4678 }
4679 }
4680 #endif // ASSERT
4681
4682 void G1ParScanThreadState::trim_queue() {
4683 assert(_evac_failure_cl != NULL, "not set");
4684
4685 StarTask ref;
4686 do {
4687 // Drain the overflow stack first, so other threads can steal.
4688 while (refs()->pop_overflow(ref)) {
4689 deal_with_reference(ref);
4690 }
4691
4692 while (refs()->pop_local(ref)) {
4693 deal_with_reference(ref);
4694 }
4695 } while (!refs()->is_empty());
4696 }
4697
4698 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4699 G1ParScanThreadState* par_scan_state) :
4700 _g1(g1), _par_scan_state(par_scan_state),
4701 _worker_id(par_scan_state->queue_num()) { }
4702
4703 void G1ParCopyHelper::mark_object(oop obj) {
4704 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4705
4706 // We know that the object is not moving so it's safe to read its size.
4707 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4708 }
4709
4710 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4711 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4712 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4713 assert(from_obj != to_obj, "should not be self-forwarded");
4714
4715 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4716 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4717
4718 // The object might be in the process of being copied by another
4719 // worker so we cannot trust that its to-space image is
4720 // well-formed. So we have to read its size from its from-space
4721 // image which we know should not be changing.
4722 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4723 }
4724
4725 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4726 size_t word_sz = old->size();
4727 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4728 // +1 to make the -1 indexes valid...
4729 int young_index = from_region->young_index_in_cset()+1;
4730 assert( (from_region->is_young() && young_index > 0) ||
4731 (!from_region->is_young() && young_index == 0), "invariant" );
4732 G1CollectorPolicy* g1p = _g1h->g1_policy();
4733 markOop m = old->mark();
4734 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4735 : m->age();
4736 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4737 word_sz);
4738 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4739 #ifndef PRODUCT
4740 // Should this evacuation fail?
4741 if (_g1h->evacuation_should_fail()) {
4742 if (obj_ptr != NULL) {
4743 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4744 obj_ptr = NULL;
4745 }
4746 }
4747 #endif // !PRODUCT
4748
4749 if (obj_ptr == NULL) {
4750 // This will either forward-to-self, or detect that someone else has
4751 // installed a forwarding pointer.
4752 return _g1h->handle_evacuation_failure_par(this, old);
4753 }
4754
4755 oop obj = oop(obj_ptr);
4756
4757 // We're going to allocate linearly, so might as well prefetch ahead.
4758 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4759
4760 oop forward_ptr = old->forward_to_atomic(obj);
4761 if (forward_ptr == NULL) {
4762 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4763
4764 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4765 // we actually allocated from and update alloc_purpose accordingly
4766 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4767 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4768
4769 if (g1p->track_object_age(alloc_purpose)) {
4770 // We could simply do obj->incr_age(). However, this causes a
4771 // performance issue. obj->incr_age() will first check whether
4772 // the object has a displaced mark by checking its mark word;
4773 // getting the mark word from the new location of the object
4774 // stalls. So, given that we already have the mark word and we
4775 // are about to install it anyway, it's better to increase the
4776 // age on the mark word, when the object does not have a
4777 // displaced mark word. We're not expecting many objects to have
4778 // a displaced marked word, so that case is not optimized
4779 // further (it could be...) and we simply call obj->incr_age().
4780
4781 if (m->has_displaced_mark_helper()) {
4782 // in this case, we have to install the mark word first,
4783 // otherwise obj looks to be forwarded (the old mark word,
4784 // which contains the forward pointer, was copied)
4785 obj->set_mark(m);
4786 obj->incr_age();
4787 } else {
4788 m = m->incr_age();
4789 obj->set_mark(m);
4790 }
4791 age_table()->add(obj, word_sz);
4792 } else {
4793 obj->set_mark(m);
4794 }
4795
4796 if (G1StringDedup::is_enabled()) {
4797 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4798 to_region->is_young(),
4799 queue_num(),
4800 obj);
4801 }
4802
4803 size_t* surv_young_words = surviving_young_words();
4804 surv_young_words[young_index] += word_sz;
4805
4806 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4807 // We keep track of the next start index in the length field of
4808 // the to-space object. The actual length can be found in the
4809 // length field of the from-space object.
4810 arrayOop(obj)->set_length(0);
4811 oop* old_p = set_partial_array_mask(old);
4812 push_on_queue(old_p);
4813 } else {
4814 // No point in using the slower heap_region_containing() method,
4815 // given that we know obj is in the heap.
4816 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4817 obj->oop_iterate_backwards(&_scanner);
4818 }
4819 } else {
4820 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4821 obj = forward_ptr;
4822 }
4823 return obj;
4824 }
4825
4826 template <class T>
4827 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4828 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4829 _scanned_klass->record_modified_oops();
4830 }
4831 }
4832
4833 template <G1Barrier barrier, bool do_mark_object>
4834 template <class T>
4835 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4836 T heap_oop = oopDesc::load_heap_oop(p);
4837
4838 if (oopDesc::is_null(heap_oop)) {
4839 return;
4840 }
4841
4842 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4843
4844 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4845
4846 if (_g1->in_cset_fast_test(obj)) {
4847 oop forwardee;
4848 if (obj->is_forwarded()) {
4849 forwardee = obj->forwardee();
4850 } else {
4851 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4852 }
4853 assert(forwardee != NULL, "forwardee should not be NULL");
4854 oopDesc::encode_store_heap_oop(p, forwardee);
4855 if (do_mark_object && forwardee != obj) {
4856 // If the object is self-forwarded we don't need to explicitly
4857 // mark it, the evacuation failure protocol will do so.
4858 mark_forwarded_object(obj, forwardee);
4859 }
4860
4861 if (barrier == G1BarrierKlass) {
4862 do_klass_barrier(p, forwardee);
4863 }
4864 } else {
4865 // The object is not in collection set. If we're a root scanning
4866 // closure during an initial mark pause (i.e. do_mark_object will
4867 // be true) then attempt to mark the object.
4868 if (do_mark_object) {
4869 mark_object(obj);
4870 }
4871 }
4872
4873 if (barrier == G1BarrierEvac) {
4874 _par_scan_state->update_rs(_from, p, _worker_id);
4875 }
4876 }
4877
4878 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4879 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4880
4881 class G1ParEvacuateFollowersClosure : public VoidClosure {
4882 protected:
4883 G1CollectedHeap* _g1h;
4884 G1ParScanThreadState* _par_scan_state;
4885 RefToScanQueueSet* _queues;
4886 ParallelTaskTerminator* _terminator;
4887
4888 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4889 RefToScanQueueSet* queues() { return _queues; }
4890 ParallelTaskTerminator* terminator() { return _terminator; }
4891
4892 public:
4893 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4894 G1ParScanThreadState* par_scan_state,
4895 RefToScanQueueSet* queues,
4896 ParallelTaskTerminator* terminator)
4897 : _g1h(g1h), _par_scan_state(par_scan_state),
4898 _queues(queues), _terminator(terminator) {}
4899
4900 void do_void();
4901
4902 private:
4903 inline bool offer_termination();
4904 };
4905
4906 bool G1ParEvacuateFollowersClosure::offer_termination() {
4907 G1ParScanThreadState* const pss = par_scan_state();
4908 pss->start_term_time();
4909 const bool res = terminator()->offer_termination();
4910 pss->end_term_time();
4911 return res;
4912 }
4913
4914 void G1ParEvacuateFollowersClosure::do_void() {
4915 StarTask stolen_task;
4916 G1ParScanThreadState* const pss = par_scan_state();
4917 pss->trim_queue();
4918
4919 do {
4920 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4921 assert(pss->verify_task(stolen_task), "sanity");
4922 if (stolen_task.is_narrow()) {
4923 pss->deal_with_reference((narrowOop*) stolen_task);
4924 } else {
4925 pss->deal_with_reference((oop*) stolen_task);
4926 }
4927
4928 // We've just processed a reference and we might have made
4929 // available new entries on the queues. So we have to make sure
4930 // we drain the queues as necessary.
4931 pss->trim_queue();
4932 }
4933 } while (!offer_termination());
4934 }
4935
4936 class G1KlassScanClosure : public KlassClosure {
4937 G1ParCopyHelper* _closure;
4938 bool _process_only_dirty;
4939 int _count;
4940 public:
4941 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4942 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4943 void do_klass(Klass* klass) {
4944 // If the klass has not been dirtied we know that there's
4945 // no references into the young gen and we can skip it.
4946 if (!_process_only_dirty || klass->has_modified_oops()) {
4947 // Clean the klass since we're going to scavenge all the metadata.
4948 klass->clear_modified_oops();
4949
4950 // Tell the closure that this klass is the Klass to scavenge
4951 // and is the one to dirty if oops are left pointing into the young gen.
4952 _closure->set_scanned_klass(klass);
4953
4954 klass->oops_do(_closure);
4955
4956 _closure->set_scanned_klass(NULL);
4957 }
4958 _count++;
4959 }
4960 };
4961
4962 class G1ParTask : public AbstractGangTask {
4963 protected:
4964 G1CollectedHeap* _g1h;
4965 RefToScanQueueSet *_queues;
4966 ParallelTaskTerminator _terminator;
4967 uint _n_workers;
4968
4969 Mutex _stats_lock;
4970 Mutex* stats_lock() { return &_stats_lock; }
4971
4972 size_t getNCards() {
4973 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4974 / G1BlockOffsetSharedArray::N_bytes;
4975 }
4976
4977 public:
4978 G1ParTask(G1CollectedHeap* g1h,
4979 RefToScanQueueSet *task_queues)
4980 : AbstractGangTask("G1 collection"),
4981 _g1h(g1h),
4982 _queues(task_queues),
4983 _terminator(0, _queues),
4984 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4985 {}
4986
4987 RefToScanQueueSet* queues() { return _queues; }
4988
4989 RefToScanQueue *work_queue(int i) {
4990 return queues()->queue(i);
4991 }
4992
4993 ParallelTaskTerminator* terminator() { return &_terminator; }
4994
4995 virtual void set_for_termination(int active_workers) {
4996 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4997 // in the young space (_par_seq_tasks) in the G1 heap
4998 // for SequentialSubTasksDone.
4999 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5000 // both of which need setting by set_n_termination().
5001 _g1h->SharedHeap::set_n_termination(active_workers);
5002 _g1h->set_n_termination(active_workers);
5003 terminator()->reset_for_reuse(active_workers);
5004 _n_workers = active_workers;
5005 }
5006
5007 void work(uint worker_id) {
5008 if (worker_id >= _n_workers) return; // no work needed this round
5009
5010 double start_time_ms = os::elapsedTime() * 1000.0;
5011 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5012
5013 {
5014 ResourceMark rm;
5015 HandleMark hm;
5016
5017 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5018
5019 G1ParScanThreadState pss(_g1h, worker_id, rp);
5020 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5021
5022 pss.set_evac_failure_closure(&evac_failure_cl);
5023
5024 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5025 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5026
5027 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5028 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5029
5030 bool only_young = _g1h->g1_policy()->gcs_are_young();
5031 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5032 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5033
5034 OopClosure* scan_root_cl = &only_scan_root_cl;
5035 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5036
5037 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5038 // We also need to mark copied objects.
5039 scan_root_cl = &scan_mark_root_cl;
5040 scan_klasses_cl = &scan_mark_klasses_cl_s;
5041 }
5042
5043 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5044
5045 // Don't scan the scavengable methods in the code cache as part
5046 // of strong root scanning. The code roots that point into a
5047 // region in the collection set are scanned when we scan the
5048 // region's RSet.
5049 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5050
5051 pss.start_strong_roots();
5052 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5053 SharedHeap::ScanningOption(so),
5054 scan_root_cl,
5055 &push_heap_rs_cl,
5056 scan_klasses_cl,
5057 worker_id);
5058 pss.end_strong_roots();
5059
5060 {
5061 double start = os::elapsedTime();
5062 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5063 evac.do_void();
5064 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5065 double term_ms = pss.term_time()*1000.0;
5066 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5067 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5068 }
5069 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5070 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5071
5072 if (ParallelGCVerbose) {
5073 MutexLocker x(stats_lock());
5074 pss.print_termination_stats(worker_id);
5075 }
5076
5077 assert(pss.refs()->is_empty(), "should be empty");
5078
5079 // Close the inner scope so that the ResourceMark and HandleMark
5080 // destructors are executed here and are included as part of the
5081 // "GC Worker Time".
5082 }
5083
5084 double end_time_ms = os::elapsedTime() * 1000.0;
5085 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5086 }
5087 };
5088
5089 // *** Common G1 Evacuation Stuff
5090
5091 // This method is run in a GC worker.
5092
5093 void
5094 G1CollectedHeap::
5095 g1_process_strong_roots(bool is_scavenging,
5096 ScanningOption so,
5097 OopClosure* scan_non_heap_roots,
5098 OopsInHeapRegionClosure* scan_rs,
5099 G1KlassScanClosure* scan_klasses,
5100 uint worker_i) {
5101
5102 // First scan the strong roots
5103 double ext_roots_start = os::elapsedTime();
5104 double closure_app_time_sec = 0.0;
5105
5106 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5107
5108 process_strong_roots(false, // no scoping; this is parallel code
5109 so,
5110 &buf_scan_non_heap_roots,
5111 scan_klasses
5112 );
5113
5114 // Now the CM ref_processor roots.
5115 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5116 // We need to treat the discovered reference lists of the
5117 // concurrent mark ref processor as roots and keep entries
5118 // (which are added by the marking threads) on them live
5119 // until they can be processed at the end of marking.
5120 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5121 }
5122
5123 // Finish up any enqueued closure apps (attributed as object copy time).
5124 buf_scan_non_heap_roots.done();
5125
5126 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5127
5128 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5129
5130 double ext_root_time_ms =
5131 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5132
5133 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5134
5135 // During conc marking we have to filter the per-thread SATB buffers
5136 // to make sure we remove any oops into the CSet (which will show up
5137 // as implicitly live).
5138 double satb_filtering_ms = 0.0;
5139 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5140 if (mark_in_progress()) {
5141 double satb_filter_start = os::elapsedTime();
5142
5143 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5144
5145 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5146 }
5147 }
5148 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5149
5150 // If this is an initial mark pause, and we're not scanning
5151 // the entire code cache, we need to mark the oops in the
5152 // strong code root lists for the regions that are not in
5153 // the collection set.
5154 // Note all threads participate in this set of root tasks.
5155 double mark_strong_code_roots_ms = 0.0;
5156 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5157 double mark_strong_roots_start = os::elapsedTime();
5158 mark_strong_code_roots(worker_i);
5159 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5160 }
5161 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5162
5163 // Now scan the complement of the collection set.
5164 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5165 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5166
5167 _process_strong_tasks->all_tasks_completed();
5168 }
5169
5170 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5171 private:
5172 BoolObjectClosure* _is_alive;
5173 int _initial_string_table_size;
5174 int _initial_symbol_table_size;
5175
5176 bool _process_strings;
5177 int _strings_processed;
5178 int _strings_removed;
5179
5180 bool _process_symbols;
5181 int _symbols_processed;
5182 int _symbols_removed;
5183
5184 bool _do_in_parallel;
5185 public:
5186 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5187 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5188 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5189 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5190 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5191
5192 _initial_string_table_size = StringTable::the_table()->table_size();
5193 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5194 if (process_strings) {
5195 StringTable::clear_parallel_claimed_index();
5196 }
5197 if (process_symbols) {
5198 SymbolTable::clear_parallel_claimed_index();
5199 }
5200 }
5201
5202 ~G1StringSymbolTableUnlinkTask() {
5203 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5204 err_msg("claim value %d after unlink less than initial string table size %d",
5205 StringTable::parallel_claimed_index(), _initial_string_table_size));
5206 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5207 err_msg("claim value %d after unlink less than initial symbol table size %d",
5208 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5209 }
5210
5211 void work(uint worker_id) {
5212 if (_do_in_parallel) {
5213 int strings_processed = 0;
5214 int strings_removed = 0;
5215 int symbols_processed = 0;
5216 int symbols_removed = 0;
5217 if (_process_strings) {
5218 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5219 Atomic::add(strings_processed, &_strings_processed);
5220 Atomic::add(strings_removed, &_strings_removed);
5221 }
5222 if (_process_symbols) {
5223 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5224 Atomic::add(symbols_processed, &_symbols_processed);
5225 Atomic::add(symbols_removed, &_symbols_removed);
5226 }
5227 } else {
5228 if (_process_strings) {
5229 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5230 }
5231 if (_process_symbols) {
5232 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5233 }
5234 }
5235 }
5236
5237 size_t strings_processed() const { return (size_t)_strings_processed; }
5238 size_t strings_removed() const { return (size_t)_strings_removed; }
5239
5240 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5241 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5242 };
5243
5244 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5245 bool process_strings, bool process_symbols) {
5246 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5247 _g1h->workers()->active_workers() : 1);
5248
5249 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5250 if (G1CollectedHeap::use_parallel_gc_threads()) {
5251 set_par_threads(n_workers);
5252 workers()->run_task(&g1_unlink_task);
5253 set_par_threads(0);
5254 } else {
5255 g1_unlink_task.work(0);
5256 }
5257 if (G1TraceStringSymbolTableScrubbing) {
5258 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5259 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5260 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5261 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5262 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5263 }
5264
5265 if (G1StringDedup::is_enabled()) {
5266 G1StringDedup::unlink(is_alive);
5267 }
5268 }
5269
5270 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5271 private:
5272 DirtyCardQueueSet* _queue;
5273 public:
5274 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5275
5276 virtual void work(uint worker_id) {
5277 double start_time = os::elapsedTime();
5278
5279 RedirtyLoggedCardTableEntryClosure cl;
5280 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5281 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5282 } else {
5283 _queue->apply_closure_to_all_completed_buffers(&cl);
5284 }
5285
5286 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5287 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5288 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5289 }
5290 };
5291
5292 void G1CollectedHeap::redirty_logged_cards() {
5293 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5294 double redirty_logged_cards_start = os::elapsedTime();
5295
5296 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5297 _g1h->workers()->active_workers() : 1);
5298
5299 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5300 dirty_card_queue_set().reset_for_par_iteration();
5301 if (use_parallel_gc_threads()) {
5302 set_par_threads(n_workers);
5303 workers()->run_task(&redirty_task);
5304 set_par_threads(0);
5305 } else {
5306 redirty_task.work(0);
5307 }
5308
5309 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5310 dcq.merge_bufferlists(&dirty_card_queue_set());
5311 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5312
5313 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5314 }
5315
5316 // Weak Reference Processing support
5317
5318 // An always "is_alive" closure that is used to preserve referents.
5319 // If the object is non-null then it's alive. Used in the preservation
5320 // of referent objects that are pointed to by reference objects
5321 // discovered by the CM ref processor.
5322 class G1AlwaysAliveClosure: public BoolObjectClosure {
5323 G1CollectedHeap* _g1;
5324 public:
5325 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5326 bool do_object_b(oop p) {
5327 if (p != NULL) {
5328 return true;
5329 }
5330 return false;
5331 }
5332 };
5333
5334 bool G1STWIsAliveClosure::do_object_b(oop p) {
5335 // An object is reachable if it is outside the collection set,
5336 // or is inside and copied.
5337 return !_g1->obj_in_cs(p) || p->is_forwarded();
5338 }
5339
5340 // Non Copying Keep Alive closure
5341 class G1KeepAliveClosure: public OopClosure {
5342 G1CollectedHeap* _g1;
5343 public:
5344 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5345 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5346 void do_oop( oop* p) {
5347 oop obj = *p;
5348
5349 if (_g1->obj_in_cs(obj)) {
5350 assert( obj->is_forwarded(), "invariant" );
5351 *p = obj->forwardee();
5352 }
5353 }
5354 };
5355
5356 // Copying Keep Alive closure - can be called from both
5357 // serial and parallel code as long as different worker
5358 // threads utilize different G1ParScanThreadState instances
5359 // and different queues.
5360
5361 class G1CopyingKeepAliveClosure: public OopClosure {
5362 G1CollectedHeap* _g1h;
5363 OopClosure* _copy_non_heap_obj_cl;
5364 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5365 G1ParScanThreadState* _par_scan_state;
5366
5367 public:
5368 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5369 OopClosure* non_heap_obj_cl,
5370 OopsInHeapRegionClosure* metadata_obj_cl,
5371 G1ParScanThreadState* pss):
5372 _g1h(g1h),
5373 _copy_non_heap_obj_cl(non_heap_obj_cl),
5374 _copy_metadata_obj_cl(metadata_obj_cl),
5375 _par_scan_state(pss)
5376 {}
5377
5378 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5379 virtual void do_oop( oop* p) { do_oop_work(p); }
5380
5381 template <class T> void do_oop_work(T* p) {
5382 oop obj = oopDesc::load_decode_heap_oop(p);
5383
5384 if (_g1h->obj_in_cs(obj)) {
5385 // If the referent object has been forwarded (either copied
5386 // to a new location or to itself in the event of an
5387 // evacuation failure) then we need to update the reference
5388 // field and, if both reference and referent are in the G1
5389 // heap, update the RSet for the referent.
5390 //
5391 // If the referent has not been forwarded then we have to keep
5392 // it alive by policy. Therefore we have copy the referent.
5393 //
5394 // If the reference field is in the G1 heap then we can push
5395 // on the PSS queue. When the queue is drained (after each
5396 // phase of reference processing) the object and it's followers
5397 // will be copied, the reference field set to point to the
5398 // new location, and the RSet updated. Otherwise we need to
5399 // use the the non-heap or metadata closures directly to copy
5400 // the referent object and update the pointer, while avoiding
5401 // updating the RSet.
5402
5403 if (_g1h->is_in_g1_reserved(p)) {
5404 _par_scan_state->push_on_queue(p);
5405 } else {
5406 assert(!Metaspace::contains((const void*)p),
5407 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5408 PTR_FORMAT, p));
5409 _copy_non_heap_obj_cl->do_oop(p);
5410 }
5411 }
5412 }
5413 };
5414
5415 // Serial drain queue closure. Called as the 'complete_gc'
5416 // closure for each discovered list in some of the
5417 // reference processing phases.
5418
5419 class G1STWDrainQueueClosure: public VoidClosure {
5420 protected:
5421 G1CollectedHeap* _g1h;
5422 G1ParScanThreadState* _par_scan_state;
5423
5424 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5425
5426 public:
5427 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5428 _g1h(g1h),
5429 _par_scan_state(pss)
5430 { }
5431
5432 void do_void() {
5433 G1ParScanThreadState* const pss = par_scan_state();
5434 pss->trim_queue();
5435 }
5436 };
5437
5438 // Parallel Reference Processing closures
5439
5440 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5441 // processing during G1 evacuation pauses.
5442
5443 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5444 private:
5445 G1CollectedHeap* _g1h;
5446 RefToScanQueueSet* _queues;
5447 FlexibleWorkGang* _workers;
5448 int _active_workers;
5449
5450 public:
5451 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5452 FlexibleWorkGang* workers,
5453 RefToScanQueueSet *task_queues,
5454 int n_workers) :
5455 _g1h(g1h),
5456 _queues(task_queues),
5457 _workers(workers),
5458 _active_workers(n_workers)
5459 {
5460 assert(n_workers > 0, "shouldn't call this otherwise");
5461 }
5462
5463 // Executes the given task using concurrent marking worker threads.
5464 virtual void execute(ProcessTask& task);
5465 virtual void execute(EnqueueTask& task);
5466 };
5467
5468 // Gang task for possibly parallel reference processing
5469
5470 class G1STWRefProcTaskProxy: public AbstractGangTask {
5471 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5472 ProcessTask& _proc_task;
5473 G1CollectedHeap* _g1h;
5474 RefToScanQueueSet *_task_queues;
5475 ParallelTaskTerminator* _terminator;
5476
5477 public:
5478 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5479 G1CollectedHeap* g1h,
5480 RefToScanQueueSet *task_queues,
5481 ParallelTaskTerminator* terminator) :
5482 AbstractGangTask("Process reference objects in parallel"),
5483 _proc_task(proc_task),
5484 _g1h(g1h),
5485 _task_queues(task_queues),
5486 _terminator(terminator)
5487 {}
5488
5489 virtual void work(uint worker_id) {
5490 // The reference processing task executed by a single worker.
5491 ResourceMark rm;
5492 HandleMark hm;
5493
5494 G1STWIsAliveClosure is_alive(_g1h);
5495
5496 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5497 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5498
5499 pss.set_evac_failure_closure(&evac_failure_cl);
5500
5501 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5502 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5503
5504 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5505 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5506
5507 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5508 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5509
5510 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5511 // We also need to mark copied objects.
5512 copy_non_heap_cl = ©_mark_non_heap_cl;
5513 copy_metadata_cl = ©_mark_metadata_cl;
5514 }
5515
5516 // Keep alive closure.
5517 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5518
5519 // Complete GC closure
5520 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5521
5522 // Call the reference processing task's work routine.
5523 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5524
5525 // Note we cannot assert that the refs array is empty here as not all
5526 // of the processing tasks (specifically phase2 - pp2_work) execute
5527 // the complete_gc closure (which ordinarily would drain the queue) so
5528 // the queue may not be empty.
5529 }
5530 };
5531
5532 // Driver routine for parallel reference processing.
5533 // Creates an instance of the ref processing gang
5534 // task and has the worker threads execute it.
5535 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5536 assert(_workers != NULL, "Need parallel worker threads.");
5537
5538 ParallelTaskTerminator terminator(_active_workers, _queues);
5539 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5540
5541 _g1h->set_par_threads(_active_workers);
5542 _workers->run_task(&proc_task_proxy);
5543 _g1h->set_par_threads(0);
5544 }
5545
5546 // Gang task for parallel reference enqueueing.
5547
5548 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5549 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5550 EnqueueTask& _enq_task;
5551
5552 public:
5553 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5554 AbstractGangTask("Enqueue reference objects in parallel"),
5555 _enq_task(enq_task)
5556 { }
5557
5558 virtual void work(uint worker_id) {
5559 _enq_task.work(worker_id);
5560 }
5561 };
5562
5563 // Driver routine for parallel reference enqueueing.
5564 // Creates an instance of the ref enqueueing gang
5565 // task and has the worker threads execute it.
5566
5567 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5568 assert(_workers != NULL, "Need parallel worker threads.");
5569
5570 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5571
5572 _g1h->set_par_threads(_active_workers);
5573 _workers->run_task(&enq_task_proxy);
5574 _g1h->set_par_threads(0);
5575 }
5576
5577 // End of weak reference support closures
5578
5579 // Abstract task used to preserve (i.e. copy) any referent objects
5580 // that are in the collection set and are pointed to by reference
5581 // objects discovered by the CM ref processor.
5582
5583 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5584 protected:
5585 G1CollectedHeap* _g1h;
5586 RefToScanQueueSet *_queues;
5587 ParallelTaskTerminator _terminator;
5588 uint _n_workers;
5589
5590 public:
5591 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5592 AbstractGangTask("ParPreserveCMReferents"),
5593 _g1h(g1h),
5594 _queues(task_queues),
5595 _terminator(workers, _queues),
5596 _n_workers(workers)
5597 { }
5598
5599 void work(uint worker_id) {
5600 ResourceMark rm;
5601 HandleMark hm;
5602
5603 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5604 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5605
5606 pss.set_evac_failure_closure(&evac_failure_cl);
5607
5608 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5609
5610
5611 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5612 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5613
5614 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5615 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5616
5617 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5618 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5619
5620 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5621 // We also need to mark copied objects.
5622 copy_non_heap_cl = ©_mark_non_heap_cl;
5623 copy_metadata_cl = ©_mark_metadata_cl;
5624 }
5625
5626 // Is alive closure
5627 G1AlwaysAliveClosure always_alive(_g1h);
5628
5629 // Copying keep alive closure. Applied to referent objects that need
5630 // to be copied.
5631 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5632
5633 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5634
5635 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5636 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5637
5638 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5639 // So this must be true - but assert just in case someone decides to
5640 // change the worker ids.
5641 assert(0 <= worker_id && worker_id < limit, "sanity");
5642 assert(!rp->discovery_is_atomic(), "check this code");
5643
5644 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5645 for (uint idx = worker_id; idx < limit; idx += stride) {
5646 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5647
5648 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5649 while (iter.has_next()) {
5650 // Since discovery is not atomic for the CM ref processor, we
5651 // can see some null referent objects.
5652 iter.load_ptrs(DEBUG_ONLY(true));
5653 oop ref = iter.obj();
5654
5655 // This will filter nulls.
5656 if (iter.is_referent_alive()) {
5657 iter.make_referent_alive();
5658 }
5659 iter.move_to_next();
5660 }
5661 }
5662
5663 // Drain the queue - which may cause stealing
5664 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5665 drain_queue.do_void();
5666 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5667 assert(pss.refs()->is_empty(), "should be");
5668 }
5669 };
5670
5671 // Weak Reference processing during an evacuation pause (part 1).
5672 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5673 double ref_proc_start = os::elapsedTime();
5674
5675 ReferenceProcessor* rp = _ref_processor_stw;
5676 assert(rp->discovery_enabled(), "should have been enabled");
5677
5678 // Any reference objects, in the collection set, that were 'discovered'
5679 // by the CM ref processor should have already been copied (either by
5680 // applying the external root copy closure to the discovered lists, or
5681 // by following an RSet entry).
5682 //
5683 // But some of the referents, that are in the collection set, that these
5684 // reference objects point to may not have been copied: the STW ref
5685 // processor would have seen that the reference object had already
5686 // been 'discovered' and would have skipped discovering the reference,
5687 // but would not have treated the reference object as a regular oop.
5688 // As a result the copy closure would not have been applied to the
5689 // referent object.
5690 //
5691 // We need to explicitly copy these referent objects - the references
5692 // will be processed at the end of remarking.
5693 //
5694 // We also need to do this copying before we process the reference
5695 // objects discovered by the STW ref processor in case one of these
5696 // referents points to another object which is also referenced by an
5697 // object discovered by the STW ref processor.
5698
5699 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5700 no_of_gc_workers == workers()->active_workers(),
5701 "Need to reset active GC workers");
5702
5703 set_par_threads(no_of_gc_workers);
5704 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5705 no_of_gc_workers,
5706 _task_queues);
5707
5708 if (G1CollectedHeap::use_parallel_gc_threads()) {
5709 workers()->run_task(&keep_cm_referents);
5710 } else {
5711 keep_cm_referents.work(0);
5712 }
5713
5714 set_par_threads(0);
5715
5716 // Closure to test whether a referent is alive.
5717 G1STWIsAliveClosure is_alive(this);
5718
5719 // Even when parallel reference processing is enabled, the processing
5720 // of JNI refs is serial and performed serially by the current thread
5721 // rather than by a worker. The following PSS will be used for processing
5722 // JNI refs.
5723
5724 // Use only a single queue for this PSS.
5725 G1ParScanThreadState pss(this, 0, NULL);
5726
5727 // We do not embed a reference processor in the copying/scanning
5728 // closures while we're actually processing the discovered
5729 // reference objects.
5730 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5731
5732 pss.set_evac_failure_closure(&evac_failure_cl);
5733
5734 assert(pss.refs()->is_empty(), "pre-condition");
5735
5736 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5737 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5738
5739 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5740 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5741
5742 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5743 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5744
5745 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5746 // We also need to mark copied objects.
5747 copy_non_heap_cl = ©_mark_non_heap_cl;
5748 copy_metadata_cl = ©_mark_metadata_cl;
5749 }
5750
5751 // Keep alive closure.
5752 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5753
5754 // Serial Complete GC closure
5755 G1STWDrainQueueClosure drain_queue(this, &pss);
5756
5757 // Setup the soft refs policy...
5758 rp->setup_policy(false);
5759
5760 ReferenceProcessorStats stats;
5761 if (!rp->processing_is_mt()) {
5762 // Serial reference processing...
5763 stats = rp->process_discovered_references(&is_alive,
5764 &keep_alive,
5765 &drain_queue,
5766 NULL,
5767 _gc_timer_stw);
5768 } else {
5769 // Parallel reference processing
5770 assert(rp->num_q() == no_of_gc_workers, "sanity");
5771 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5772
5773 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5774 stats = rp->process_discovered_references(&is_alive,
5775 &keep_alive,
5776 &drain_queue,
5777 &par_task_executor,
5778 _gc_timer_stw);
5779 }
5780
5781 _gc_tracer_stw->report_gc_reference_stats(stats);
5782
5783 // We have completed copying any necessary live referent objects.
5784 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5785
5786 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5787 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5788 }
5789
5790 // Weak Reference processing during an evacuation pause (part 2).
5791 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5792 double ref_enq_start = os::elapsedTime();
5793
5794 ReferenceProcessor* rp = _ref_processor_stw;
5795 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5796
5797 // Now enqueue any remaining on the discovered lists on to
5798 // the pending list.
5799 if (!rp->processing_is_mt()) {
5800 // Serial reference processing...
5801 rp->enqueue_discovered_references();
5802 } else {
5803 // Parallel reference enqueueing
5804
5805 assert(no_of_gc_workers == workers()->active_workers(),
5806 "Need to reset active workers");
5807 assert(rp->num_q() == no_of_gc_workers, "sanity");
5808 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5809
5810 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5811 rp->enqueue_discovered_references(&par_task_executor);
5812 }
5813
5814 rp->verify_no_references_recorded();
5815 assert(!rp->discovery_enabled(), "should have been disabled");
5816
5817 // FIXME
5818 // CM's reference processing also cleans up the string and symbol tables.
5819 // Should we do that here also? We could, but it is a serial operation
5820 // and could significantly increase the pause time.
5821
5822 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5823 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5824 }
5825
5826 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5827 _expand_heap_after_alloc_failure = true;
5828 _evacuation_failed = false;
5829
5830 // Should G1EvacuationFailureALot be in effect for this GC?
5831 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5832
5833 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5834
5835 // Disable the hot card cache.
5836 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5837 hot_card_cache->reset_hot_cache_claimed_index();
5838 hot_card_cache->set_use_cache(false);
5839
5840 uint n_workers;
5841 if (G1CollectedHeap::use_parallel_gc_threads()) {
5842 n_workers =
5843 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5844 workers()->active_workers(),
5845 Threads::number_of_non_daemon_threads());
5846 assert(UseDynamicNumberOfGCThreads ||
5847 n_workers == workers()->total_workers(),
5848 "If not dynamic should be using all the workers");
5849 workers()->set_active_workers(n_workers);
5850 set_par_threads(n_workers);
5851 } else {
5852 assert(n_par_threads() == 0,
5853 "Should be the original non-parallel value");
5854 n_workers = 1;
5855 }
5856
5857 G1ParTask g1_par_task(this, _task_queues);
5858
5859 init_for_evac_failure(NULL);
5860
5861 rem_set()->prepare_for_younger_refs_iterate(true);
5862
5863 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5864 double start_par_time_sec = os::elapsedTime();
5865 double end_par_time_sec;
5866
5867 {
5868 StrongRootsScope srs(this);
5869
5870 if (G1CollectedHeap::use_parallel_gc_threads()) {
5871 // The individual threads will set their evac-failure closures.
5872 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5873 // These tasks use ShareHeap::_process_strong_tasks
5874 assert(UseDynamicNumberOfGCThreads ||
5875 workers()->active_workers() == workers()->total_workers(),
5876 "If not dynamic should be using all the workers");
5877 workers()->run_task(&g1_par_task);
5878 } else {
5879 g1_par_task.set_for_termination(n_workers);
5880 g1_par_task.work(0);
5881 }
5882 end_par_time_sec = os::elapsedTime();
5883
5884 // Closing the inner scope will execute the destructor
5885 // for the StrongRootsScope object. We record the current
5886 // elapsed time before closing the scope so that time
5887 // taken for the SRS destructor is NOT included in the
5888 // reported parallel time.
5889 }
5890
5891 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5892 g1_policy()->phase_times()->record_par_time(par_time_ms);
5893
5894 double code_root_fixup_time_ms =
5895 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5896 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5897
5898 set_par_threads(0);
5899
5900 // Process any discovered reference objects - we have
5901 // to do this _before_ we retire the GC alloc regions
5902 // as we may have to copy some 'reachable' referent
5903 // objects (and their reachable sub-graphs) that were
5904 // not copied during the pause.
5905 process_discovered_references(n_workers);
5906
5907 // Weak root processing.
5908 {
5909 G1STWIsAliveClosure is_alive(this);
5910 G1KeepAliveClosure keep_alive(this);
5911 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5912 if (G1StringDedup::is_enabled()) {
5913 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5914 }
5915 }
5916
5917 release_gc_alloc_regions(n_workers, evacuation_info);
5918 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5919
5920 // Reset and re-enable the hot card cache.
5921 // Note the counts for the cards in the regions in the
5922 // collection set are reset when the collection set is freed.
5923 hot_card_cache->reset_hot_cache();
5924 hot_card_cache->set_use_cache(true);
5925
5926 // Migrate the strong code roots attached to each region in
5927 // the collection set. Ideally we would like to do this
5928 // after we have finished the scanning/evacuation of the
5929 // strong code roots for a particular heap region.
5930 migrate_strong_code_roots();
5931
5932 purge_code_root_memory();
5933
5934 if (g1_policy()->during_initial_mark_pause()) {
5935 // Reset the claim values set during marking the strong code roots
5936 reset_heap_region_claim_values();
5937 }
5938
5939 finalize_for_evac_failure();
5940
5941 if (evacuation_failed()) {
5942 remove_self_forwarding_pointers();
5943
5944 // Reset the G1EvacuationFailureALot counters and flags
5945 // Note: the values are reset only when an actual
5946 // evacuation failure occurs.
5947 NOT_PRODUCT(reset_evacuation_should_fail();)
5948 }
5949
5950 // Enqueue any remaining references remaining on the STW
5951 // reference processor's discovered lists. We need to do
5952 // this after the card table is cleaned (and verified) as
5953 // the act of enqueueing entries on to the pending list
5954 // will log these updates (and dirty their associated
5955 // cards). We need these updates logged to update any
5956 // RSets.
5957 enqueue_discovered_references(n_workers);
5958
5959 if (G1DeferredRSUpdate) {
5960 redirty_logged_cards();
5961 }
5962 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5963 }
5964
5965 void G1CollectedHeap::free_region(HeapRegion* hr,
5966 FreeRegionList* free_list,
5967 bool par,
5968 bool locked) {
5969 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5970 assert(!hr->is_empty(), "the region should not be empty");
5971 assert(free_list != NULL, "pre-condition");
5972
5973 if (G1VerifyBitmaps) {
5974 MemRegion mr(hr->bottom(), hr->end());
5975 concurrent_mark()->clearRangePrevBitmap(mr);
5976 }
5977
5978 // Clear the card counts for this region.
5979 // Note: we only need to do this if the region is not young
5980 // (since we don't refine cards in young regions).
5981 if (!hr->is_young()) {
5982 _cg1r->hot_card_cache()->reset_card_counts(hr);
5983 }
5984 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5985 free_list->add_ordered(hr);
5986 }
5987
5988 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5989 FreeRegionList* free_list,
5990 bool par) {
5991 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5992 assert(free_list != NULL, "pre-condition");
5993
5994 size_t hr_capacity = hr->capacity();
5995 // We need to read this before we make the region non-humongous,
5996 // otherwise the information will be gone.
5997 uint last_index = hr->last_hc_index();
5998 hr->set_notHumongous();
5999 free_region(hr, free_list, par);
6000
6001 uint i = hr->hrs_index() + 1;
6002 while (i < last_index) {
6003 HeapRegion* curr_hr = region_at(i);
6004 assert(curr_hr->continuesHumongous(), "invariant");
6005 curr_hr->set_notHumongous();
6006 free_region(curr_hr, free_list, par);
6007 i += 1;
6008 }
6009 }
6010
6011 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6012 const HeapRegionSetCount& humongous_regions_removed) {
6013 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6014 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6015 _old_set.bulk_remove(old_regions_removed);
6016 _humongous_set.bulk_remove(humongous_regions_removed);
6017 }
6018
6019 }
6020
6021 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6022 assert(list != NULL, "list can't be null");
6023 if (!list->is_empty()) {
6024 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6025 _free_list.add_ordered(list);
6026 }
6027 }
6028
6029 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6030 assert(_summary_bytes_used >= bytes,
6031 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6032 _summary_bytes_used, bytes));
6033 _summary_bytes_used -= bytes;
6034 }
6035
6036 class G1ParCleanupCTTask : public AbstractGangTask {
6037 G1SATBCardTableModRefBS* _ct_bs;
6038 G1CollectedHeap* _g1h;
6039 HeapRegion* volatile _su_head;
6040 public:
6041 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6042 G1CollectedHeap* g1h) :
6043 AbstractGangTask("G1 Par Cleanup CT Task"),
6044 _ct_bs(ct_bs), _g1h(g1h) { }
6045
6046 void work(uint worker_id) {
6047 HeapRegion* r;
6048 while (r = _g1h->pop_dirty_cards_region()) {
6049 clear_cards(r);
6050 }
6051 }
6052
6053 void clear_cards(HeapRegion* r) {
6054 // Cards of the survivors should have already been dirtied.
6055 if (!r->is_survivor()) {
6056 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6057 }
6058 }
6059 };
6060
6061 #ifndef PRODUCT
6062 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6063 G1CollectedHeap* _g1h;
6064 G1SATBCardTableModRefBS* _ct_bs;
6065 public:
6066 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6067 : _g1h(g1h), _ct_bs(ct_bs) { }
6068 virtual bool doHeapRegion(HeapRegion* r) {
6069 if (r->is_survivor()) {
6070 _g1h->verify_dirty_region(r);
6071 } else {
6072 _g1h->verify_not_dirty_region(r);
6073 }
6074 return false;
6075 }
6076 };
6077
6078 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6079 // All of the region should be clean.
6080 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6081 MemRegion mr(hr->bottom(), hr->end());
6082 ct_bs->verify_not_dirty_region(mr);
6083 }
6084
6085 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6086 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6087 // dirty allocated blocks as they allocate them. The thread that
6088 // retires each region and replaces it with a new one will do a
6089 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6090 // not dirty that area (one less thing to have to do while holding
6091 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6092 // is dirty.
6093 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6094 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6095 if (hr->is_young()) {
6096 ct_bs->verify_g1_young_region(mr);
6097 } else {
6098 ct_bs->verify_dirty_region(mr);
6099 }
6100 }
6101
6102 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6103 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6104 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6105 verify_dirty_region(hr);
6106 }
6107 }
6108
6109 void G1CollectedHeap::verify_dirty_young_regions() {
6110 verify_dirty_young_list(_young_list->first_region());
6111 }
6112
6113 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6114 HeapWord* tams, HeapWord* end) {
6115 guarantee(tams <= end,
6116 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6117 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6118 if (result < end) {
6119 gclog_or_tty->cr();
6120 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6121 bitmap_name, result);
6122 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6123 bitmap_name, tams, end);
6124 return false;
6125 }
6126 return true;
6127 }
6128
6129 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6130 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6131 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6132
6133 HeapWord* bottom = hr->bottom();
6134 HeapWord* ptams = hr->prev_top_at_mark_start();
6135 HeapWord* ntams = hr->next_top_at_mark_start();
6136 HeapWord* end = hr->end();
6137
6138 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6139
6140 bool res_n = true;
6141 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6142 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6143 // if we happen to be in that state.
6144 if (mark_in_progress() || !_cmThread->in_progress()) {
6145 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6146 }
6147 if (!res_p || !res_n) {
6148 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6149 HR_FORMAT_PARAMS(hr));
6150 gclog_or_tty->print_cr("#### Caller: %s", caller);
6151 return false;
6152 }
6153 return true;
6154 }
6155
6156 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6157 if (!G1VerifyBitmaps) return;
6158
6159 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6160 }
6161
6162 class G1VerifyBitmapClosure : public HeapRegionClosure {
6163 private:
6164 const char* _caller;
6165 G1CollectedHeap* _g1h;
6166 bool _failures;
6167
6168 public:
6169 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6170 _caller(caller), _g1h(g1h), _failures(false) { }
6171
6172 bool failures() { return _failures; }
6173
6174 virtual bool doHeapRegion(HeapRegion* hr) {
6175 if (hr->continuesHumongous()) return false;
6176
6177 bool result = _g1h->verify_bitmaps(_caller, hr);
6178 if (!result) {
6179 _failures = true;
6180 }
6181 return false;
6182 }
6183 };
6184
6185 void G1CollectedHeap::check_bitmaps(const char* caller) {
6186 if (!G1VerifyBitmaps) return;
6187
6188 G1VerifyBitmapClosure cl(caller, this);
6189 heap_region_iterate(&cl);
6190 guarantee(!cl.failures(), "bitmap verification");
6191 }
6192 #endif // PRODUCT
6193
6194 void G1CollectedHeap::cleanUpCardTable() {
6195 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6196 double start = os::elapsedTime();
6197
6198 {
6199 // Iterate over the dirty cards region list.
6200 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6201
6202 if (G1CollectedHeap::use_parallel_gc_threads()) {
6203 set_par_threads();
6204 workers()->run_task(&cleanup_task);
6205 set_par_threads(0);
6206 } else {
6207 while (_dirty_cards_region_list) {
6208 HeapRegion* r = _dirty_cards_region_list;
6209 cleanup_task.clear_cards(r);
6210 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6211 if (_dirty_cards_region_list == r) {
6212 // The last region.
6213 _dirty_cards_region_list = NULL;
6214 }
6215 r->set_next_dirty_cards_region(NULL);
6216 }
6217 }
6218 #ifndef PRODUCT
6219 if (G1VerifyCTCleanup || VerifyAfterGC) {
6220 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6221 heap_region_iterate(&cleanup_verifier);
6222 }
6223 #endif
6224 }
6225
6226 double elapsed = os::elapsedTime() - start;
6227 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6228 }
6229
6230 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6231 size_t pre_used = 0;
6232 FreeRegionList local_free_list("Local List for CSet Freeing");
6233
6234 double young_time_ms = 0.0;
6235 double non_young_time_ms = 0.0;
6236
6237 // Since the collection set is a superset of the the young list,
6238 // all we need to do to clear the young list is clear its
6239 // head and length, and unlink any young regions in the code below
6240 _young_list->clear();
6241
6242 G1CollectorPolicy* policy = g1_policy();
6243
6244 double start_sec = os::elapsedTime();
6245 bool non_young = true;
6246
6247 HeapRegion* cur = cs_head;
6248 int age_bound = -1;
6249 size_t rs_lengths = 0;
6250
6251 while (cur != NULL) {
6252 assert(!is_on_master_free_list(cur), "sanity");
6253 if (non_young) {
6254 if (cur->is_young()) {
6255 double end_sec = os::elapsedTime();
6256 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6257 non_young_time_ms += elapsed_ms;
6258
6259 start_sec = os::elapsedTime();
6260 non_young = false;
6261 }
6262 } else {
6263 if (!cur->is_young()) {
6264 double end_sec = os::elapsedTime();
6265 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6266 young_time_ms += elapsed_ms;
6267
6268 start_sec = os::elapsedTime();
6269 non_young = true;
6270 }
6271 }
6272
6273 rs_lengths += cur->rem_set()->occupied_locked();
6274
6275 HeapRegion* next = cur->next_in_collection_set();
6276 assert(cur->in_collection_set(), "bad CS");
6277 cur->set_next_in_collection_set(NULL);
6278 cur->set_in_collection_set(false);
6279
6280 if (cur->is_young()) {
6281 int index = cur->young_index_in_cset();
6282 assert(index != -1, "invariant");
6283 assert((uint) index < policy->young_cset_region_length(), "invariant");
6284 size_t words_survived = _surviving_young_words[index];
6285 cur->record_surv_words_in_group(words_survived);
6286
6287 // At this point the we have 'popped' cur from the collection set
6288 // (linked via next_in_collection_set()) but it is still in the
6289 // young list (linked via next_young_region()). Clear the
6290 // _next_young_region field.
6291 cur->set_next_young_region(NULL);
6292 } else {
6293 int index = cur->young_index_in_cset();
6294 assert(index == -1, "invariant");
6295 }
6296
6297 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6298 (!cur->is_young() && cur->young_index_in_cset() == -1),
6299 "invariant" );
6300
6301 if (!cur->evacuation_failed()) {
6302 MemRegion used_mr = cur->used_region();
6303
6304 // And the region is empty.
6305 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6306 pre_used += cur->used();
6307 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6308 } else {
6309 cur->uninstall_surv_rate_group();
6310 if (cur->is_young()) {
6311 cur->set_young_index_in_cset(-1);
6312 }
6313 cur->set_not_young();
6314 cur->set_evacuation_failed(false);
6315 // The region is now considered to be old.
6316 _old_set.add(cur);
6317 evacuation_info.increment_collectionset_used_after(cur->used());
6318 }
6319 cur = next;
6320 }
6321
6322 evacuation_info.set_regions_freed(local_free_list.length());
6323 policy->record_max_rs_lengths(rs_lengths);
6324 policy->cset_regions_freed();
6325
6326 double end_sec = os::elapsedTime();
6327 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6328
6329 if (non_young) {
6330 non_young_time_ms += elapsed_ms;
6331 } else {
6332 young_time_ms += elapsed_ms;
6333 }
6334
6335 prepend_to_freelist(&local_free_list);
6336 decrement_summary_bytes(pre_used);
6337 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6338 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6339 }
6340
6341 // This routine is similar to the above but does not record
6342 // any policy statistics or update free lists; we are abandoning
6343 // the current incremental collection set in preparation of a
6344 // full collection. After the full GC we will start to build up
6345 // the incremental collection set again.
6346 // This is only called when we're doing a full collection
6347 // and is immediately followed by the tearing down of the young list.
6348
6349 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6350 HeapRegion* cur = cs_head;
6351
6352 while (cur != NULL) {
6353 HeapRegion* next = cur->next_in_collection_set();
6354 assert(cur->in_collection_set(), "bad CS");
6355 cur->set_next_in_collection_set(NULL);
6356 cur->set_in_collection_set(false);
6357 cur->set_young_index_in_cset(-1);
6358 cur = next;
6359 }
6360 }
6361
6362 void G1CollectedHeap::set_free_regions_coming() {
6363 if (G1ConcRegionFreeingVerbose) {
6364 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6365 "setting free regions coming");
6366 }
6367
6368 assert(!free_regions_coming(), "pre-condition");
6369 _free_regions_coming = true;
6370 }
6371
6372 void G1CollectedHeap::reset_free_regions_coming() {
6373 assert(free_regions_coming(), "pre-condition");
6374
6375 {
6376 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6377 _free_regions_coming = false;
6378 SecondaryFreeList_lock->notify_all();
6379 }
6380
6381 if (G1ConcRegionFreeingVerbose) {
6382 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6383 "reset free regions coming");
6384 }
6385 }
6386
6387 void G1CollectedHeap::wait_while_free_regions_coming() {
6388 // Most of the time we won't have to wait, so let's do a quick test
6389 // first before we take the lock.
6390 if (!free_regions_coming()) {
6391 return;
6392 }
6393
6394 if (G1ConcRegionFreeingVerbose) {
6395 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6396 "waiting for free regions");
6397 }
6398
6399 {
6400 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6401 while (free_regions_coming()) {
6402 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6403 }
6404 }
6405
6406 if (G1ConcRegionFreeingVerbose) {
6407 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6408 "done waiting for free regions");
6409 }
6410 }
6411
6412 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6413 assert(heap_lock_held_for_gc(),
6414 "the heap lock should already be held by or for this thread");
6415 _young_list->push_region(hr);
6416 }
6417
6418 class NoYoungRegionsClosure: public HeapRegionClosure {
6419 private:
6420 bool _success;
6421 public:
6422 NoYoungRegionsClosure() : _success(true) { }
6423 bool doHeapRegion(HeapRegion* r) {
6424 if (r->is_young()) {
6425 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6426 r->bottom(), r->end());
6427 _success = false;
6428 }
6429 return false;
6430 }
6431 bool success() { return _success; }
6432 };
6433
6434 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6435 bool ret = _young_list->check_list_empty(check_sample);
6436
6437 if (check_heap) {
6438 NoYoungRegionsClosure closure;
6439 heap_region_iterate(&closure);
6440 ret = ret && closure.success();
6441 }
6442
6443 return ret;
6444 }
6445
6446 class TearDownRegionSetsClosure : public HeapRegionClosure {
6447 private:
6448 HeapRegionSet *_old_set;
6449
6450 public:
6451 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6452
6453 bool doHeapRegion(HeapRegion* r) {
6454 if (r->is_empty()) {
6455 // We ignore empty regions, we'll empty the free list afterwards
6456 } else if (r->is_young()) {
6457 // We ignore young regions, we'll empty the young list afterwards
6458 } else if (r->isHumongous()) {
6459 // We ignore humongous regions, we're not tearing down the
6460 // humongous region set
6461 } else {
6462 // The rest should be old
6463 _old_set->remove(r);
6464 }
6465 return false;
6466 }
6467
6468 ~TearDownRegionSetsClosure() {
6469 assert(_old_set->is_empty(), "post-condition");
6470 }
6471 };
6472
6473 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6474 assert_at_safepoint(true /* should_be_vm_thread */);
6475
6476 if (!free_list_only) {
6477 TearDownRegionSetsClosure cl(&_old_set);
6478 heap_region_iterate(&cl);
6479
6480 // Note that emptying the _young_list is postponed and instead done as
6481 // the first step when rebuilding the regions sets again. The reason for
6482 // this is that during a full GC string deduplication needs to know if
6483 // a collected region was young or old when the full GC was initiated.
6484 }
6485 _free_list.remove_all();
6486 }
6487
6488 class RebuildRegionSetsClosure : public HeapRegionClosure {
6489 private:
6490 bool _free_list_only;
6491 HeapRegionSet* _old_set;
6492 FreeRegionList* _free_list;
6493 size_t _total_used;
6494
6495 public:
6496 RebuildRegionSetsClosure(bool free_list_only,
6497 HeapRegionSet* old_set, FreeRegionList* free_list) :
6498 _free_list_only(free_list_only),
6499 _old_set(old_set), _free_list(free_list), _total_used(0) {
6500 assert(_free_list->is_empty(), "pre-condition");
6501 if (!free_list_only) {
6502 assert(_old_set->is_empty(), "pre-condition");
6503 }
6504 }
6505
6506 bool doHeapRegion(HeapRegion* r) {
6507 if (r->continuesHumongous()) {
6508 return false;
6509 }
6510
6511 if (r->is_empty()) {
6512 // Add free regions to the free list
6513 _free_list->add_as_tail(r);
6514 } else if (!_free_list_only) {
6515 assert(!r->is_young(), "we should not come across young regions");
6516
6517 if (r->isHumongous()) {
6518 // We ignore humongous regions, we left the humongous set unchanged
6519 } else {
6520 // The rest should be old, add them to the old set
6521 _old_set->add(r);
6522 }
6523 _total_used += r->used();
6524 }
6525
6526 return false;
6527 }
6528
6529 size_t total_used() {
6530 return _total_used;
6531 }
6532 };
6533
6534 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6535 assert_at_safepoint(true /* should_be_vm_thread */);
6536
6537 if (!free_list_only) {
6538 _young_list->empty_list();
6539 }
6540
6541 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6542 heap_region_iterate(&cl);
6543
6544 if (!free_list_only) {
6545 _summary_bytes_used = cl.total_used();
6546 }
6547 assert(_summary_bytes_used == recalculate_used(),
6548 err_msg("inconsistent _summary_bytes_used, "
6549 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6550 _summary_bytes_used, recalculate_used()));
6551 }
6552
6553 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6554 _refine_cte_cl->set_concurrent(concurrent);
6555 }
6556
6557 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6558 HeapRegion* hr = heap_region_containing(p);
6559 return hr->is_in(p);
6560 }
6561
6562 // Methods for the mutator alloc region
6563
6564 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6565 bool force) {
6566 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6567 assert(!force || g1_policy()->can_expand_young_list(),
6568 "if force is true we should be able to expand the young list");
6569 bool young_list_full = g1_policy()->is_young_list_full();
6570 if (force || !young_list_full) {
6571 HeapRegion* new_alloc_region = new_region(word_size,
6572 false /* is_old */,
6573 false /* do_expand */);
6574 if (new_alloc_region != NULL) {
6575 set_region_short_lived_locked(new_alloc_region);
6576 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6577 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6578 return new_alloc_region;
6579 }
6580 }
6581 return NULL;
6582 }
6583
6584 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6585 size_t allocated_bytes) {
6586 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6587 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6588
6589 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6590 _summary_bytes_used += allocated_bytes;
6591 _hr_printer.retire(alloc_region);
6592 // We update the eden sizes here, when the region is retired,
6593 // instead of when it's allocated, since this is the point that its
6594 // used space has been recored in _summary_bytes_used.
6595 g1mm()->update_eden_size();
6596 }
6597
6598 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6599 bool force) {
6600 return _g1h->new_mutator_alloc_region(word_size, force);
6601 }
6602
6603 void G1CollectedHeap::set_par_threads() {
6604 // Don't change the number of workers. Use the value previously set
6605 // in the workgroup.
6606 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6607 uint n_workers = workers()->active_workers();
6608 assert(UseDynamicNumberOfGCThreads ||
6609 n_workers == workers()->total_workers(),
6610 "Otherwise should be using the total number of workers");
6611 if (n_workers == 0) {
6612 assert(false, "Should have been set in prior evacuation pause.");
6613 n_workers = ParallelGCThreads;
6614 workers()->set_active_workers(n_workers);
6615 }
6616 set_par_threads(n_workers);
6617 }
6618
6619 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6620 size_t allocated_bytes) {
6621 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6622 }
6623
6624 // Methods for the GC alloc regions
6625
6626 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6627 uint count,
6628 GCAllocPurpose ap) {
6629 assert(FreeList_lock->owned_by_self(), "pre-condition");
6630
6631 if (count < g1_policy()->max_regions(ap)) {
6632 bool survivor = (ap == GCAllocForSurvived);
6633 HeapRegion* new_alloc_region = new_region(word_size,
6634 !survivor,
6635 true /* do_expand */);
6636 if (new_alloc_region != NULL) {
6637 // We really only need to do this for old regions given that we
6638 // should never scan survivors. But it doesn't hurt to do it
6639 // for survivors too.
6640 new_alloc_region->set_saved_mark();
6641 if (survivor) {
6642 new_alloc_region->set_survivor();
6643 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6644 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6645 } else {
6646 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6647 check_bitmaps("Old Region Allocation", new_alloc_region);
6648 }
6649 bool during_im = g1_policy()->during_initial_mark_pause();
6650 new_alloc_region->note_start_of_copying(during_im);
6651 return new_alloc_region;
6652 } else {
6653 g1_policy()->note_alloc_region_limit_reached(ap);
6654 }
6655 }
6656 return NULL;
6657 }
6658
6659 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6660 size_t allocated_bytes,
6661 GCAllocPurpose ap) {
6662 bool during_im = g1_policy()->during_initial_mark_pause();
6663 alloc_region->note_end_of_copying(during_im);
6664 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6665 if (ap == GCAllocForSurvived) {
6666 young_list()->add_survivor_region(alloc_region);
6667 } else {
6668 _old_set.add(alloc_region);
6669 }
6670 _hr_printer.retire(alloc_region);
6671 }
6672
6673 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6674 bool force) {
6675 assert(!force, "not supported for GC alloc regions");
6676 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6677 }
6678
6679 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6680 size_t allocated_bytes) {
6681 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6682 GCAllocForSurvived);
6683 }
6684
6685 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6686 bool force) {
6687 assert(!force, "not supported for GC alloc regions");
6688 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6689 }
6690
6691 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6692 size_t allocated_bytes) {
6693 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6694 GCAllocForTenured);
6695 }
6696 // Heap region set verification
6697
6698 class VerifyRegionListsClosure : public HeapRegionClosure {
6699 private:
6700 HeapRegionSet* _old_set;
6701 HeapRegionSet* _humongous_set;
6702 FreeRegionList* _free_list;
6703
6704 public:
6705 HeapRegionSetCount _old_count;
6706 HeapRegionSetCount _humongous_count;
6707 HeapRegionSetCount _free_count;
6708
6709 VerifyRegionListsClosure(HeapRegionSet* old_set,
6710 HeapRegionSet* humongous_set,
6711 FreeRegionList* free_list) :
6712 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6713 _old_count(), _humongous_count(), _free_count(){ }
6714
6715 bool doHeapRegion(HeapRegion* hr) {
6716 if (hr->continuesHumongous()) {
6717 return false;
6718 }
6719
6720 if (hr->is_young()) {
6721 // TODO
6722 } else if (hr->startsHumongous()) {
6723 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6724 _humongous_count.increment(1u, hr->capacity());
6725 } else if (hr->is_empty()) {
6726 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6727 _free_count.increment(1u, hr->capacity());
6728 } else {
6729 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6730 _old_count.increment(1u, hr->capacity());
6731 }
6732 return false;
6733 }
6734
6735 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6736 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6737 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6738 old_set->total_capacity_bytes(), _old_count.capacity()));
6739
6740 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6741 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6742 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6743
6744 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6745 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6746 free_list->total_capacity_bytes(), _free_count.capacity()));
6747 }
6748 };
6749
6750 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6751 HeapWord* bottom) {
6752 HeapWord* end = bottom + HeapRegion::GrainWords;
6753 MemRegion mr(bottom, end);
6754 assert(_g1_reserved.contains(mr), "invariant");
6755 // This might return NULL if the allocation fails
6756 return new HeapRegion(hrs_index, _bot_shared, mr);
6757 }
6758
6759 void G1CollectedHeap::verify_region_sets() {
6760 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6761
6762 // First, check the explicit lists.
6763 _free_list.verify_list();
6764 {
6765 // Given that a concurrent operation might be adding regions to
6766 // the secondary free list we have to take the lock before
6767 // verifying it.
6768 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6769 _secondary_free_list.verify_list();
6770 }
6771
6772 // If a concurrent region freeing operation is in progress it will
6773 // be difficult to correctly attributed any free regions we come
6774 // across to the correct free list given that they might belong to
6775 // one of several (free_list, secondary_free_list, any local lists,
6776 // etc.). So, if that's the case we will skip the rest of the
6777 // verification operation. Alternatively, waiting for the concurrent
6778 // operation to complete will have a non-trivial effect on the GC's
6779 // operation (no concurrent operation will last longer than the
6780 // interval between two calls to verification) and it might hide
6781 // any issues that we would like to catch during testing.
6782 if (free_regions_coming()) {
6783 return;
6784 }
6785
6786 // Make sure we append the secondary_free_list on the free_list so
6787 // that all free regions we will come across can be safely
6788 // attributed to the free_list.
6789 append_secondary_free_list_if_not_empty_with_lock();
6790
6791 // Finally, make sure that the region accounting in the lists is
6792 // consistent with what we see in the heap.
6793
6794 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6795 heap_region_iterate(&cl);
6796 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6797 }
6798
6799 // Optimized nmethod scanning
6800
6801 class RegisterNMethodOopClosure: public OopClosure {
6802 G1CollectedHeap* _g1h;
6803 nmethod* _nm;
6804
6805 template <class T> void do_oop_work(T* p) {
6806 T heap_oop = oopDesc::load_heap_oop(p);
6807 if (!oopDesc::is_null(heap_oop)) {
6808 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6809 HeapRegion* hr = _g1h->heap_region_containing(obj);
6810 assert(!hr->continuesHumongous(),
6811 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6812 " starting at "HR_FORMAT,
6813 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6814
6815 // HeapRegion::add_strong_code_root() avoids adding duplicate
6816 // entries but having duplicates is OK since we "mark" nmethods
6817 // as visited when we scan the strong code root lists during the GC.
6818 hr->add_strong_code_root(_nm);
6819 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6820 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6821 _nm, HR_FORMAT_PARAMS(hr)));
6822 }
6823 }
6824
6825 public:
6826 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6827 _g1h(g1h), _nm(nm) {}
6828
6829 void do_oop(oop* p) { do_oop_work(p); }
6830 void do_oop(narrowOop* p) { do_oop_work(p); }
6831 };
6832
6833 class UnregisterNMethodOopClosure: public OopClosure {
6834 G1CollectedHeap* _g1h;
6835 nmethod* _nm;
6836
6837 template <class T> void do_oop_work(T* p) {
6838 T heap_oop = oopDesc::load_heap_oop(p);
6839 if (!oopDesc::is_null(heap_oop)) {
6840 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6841 HeapRegion* hr = _g1h->heap_region_containing(obj);
6842 assert(!hr->continuesHumongous(),
6843 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6844 " starting at "HR_FORMAT,
6845 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6846
6847 hr->remove_strong_code_root(_nm);
6848 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6849 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6850 _nm, HR_FORMAT_PARAMS(hr)));
6851 }
6852 }
6853
6854 public:
6855 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6856 _g1h(g1h), _nm(nm) {}
6857
6858 void do_oop(oop* p) { do_oop_work(p); }
6859 void do_oop(narrowOop* p) { do_oop_work(p); }
6860 };
6861
6862 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6863 CollectedHeap::register_nmethod(nm);
6864
6865 guarantee(nm != NULL, "sanity");
6866 RegisterNMethodOopClosure reg_cl(this, nm);
6867 nm->oops_do(®_cl);
6868 }
6869
6870 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6871 CollectedHeap::unregister_nmethod(nm);
6872
6873 guarantee(nm != NULL, "sanity");
6874 UnregisterNMethodOopClosure reg_cl(this, nm);
6875 nm->oops_do(®_cl, true);
6876 }
6877
6878 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6879 public:
6880 bool doHeapRegion(HeapRegion *hr) {
6881 assert(!hr->isHumongous(),
6882 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6883 HR_FORMAT_PARAMS(hr)));
6884 hr->migrate_strong_code_roots();
6885 return false;
6886 }
6887 };
6888
6889 void G1CollectedHeap::migrate_strong_code_roots() {
6890 MigrateCodeRootsHeapRegionClosure cl;
6891 double migrate_start = os::elapsedTime();
6892 collection_set_iterate(&cl);
6893 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6894 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6895 }
6896
6897 void G1CollectedHeap::purge_code_root_memory() {
6898 double purge_start = os::elapsedTime();
6899 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6900 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6901 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6902 }
6903
6904 // Mark all the code roots that point into regions *not* in the
6905 // collection set.
6906 //
6907 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6908 // walking the the code roots lists of regions not in the collection
6909 // set. Suppose we have an nmethod (M) that points to objects in two
6910 // separate regions - one in the collection set (R1) and one not (R2).
6911 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6912 // nmethod M when walking the code roots for R1. When we come to scan
6913 // the code roots for R2, we would see that M is already marked and it
6914 // would be skipped and the objects in R2 that are referenced from M
6915 // would not be evacuated.
6916
6917 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6918
6919 class MarkStrongCodeRootOopClosure: public OopClosure {
6920 ConcurrentMark* _cm;
6921 HeapRegion* _hr;
6922 uint _worker_id;
6923
6924 template <class T> void do_oop_work(T* p) {
6925 T heap_oop = oopDesc::load_heap_oop(p);
6926 if (!oopDesc::is_null(heap_oop)) {
6927 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6928 // Only mark objects in the region (which is assumed
6929 // to be not in the collection set).
6930 if (_hr->is_in(obj)) {
6931 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6932 }
6933 }
6934 }
6935
6936 public:
6937 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6938 _cm(cm), _hr(hr), _worker_id(worker_id) {
6939 assert(!_hr->in_collection_set(), "sanity");
6940 }
6941
6942 void do_oop(narrowOop* p) { do_oop_work(p); }
6943 void do_oop(oop* p) { do_oop_work(p); }
6944 };
6945
6946 MarkStrongCodeRootOopClosure _oop_cl;
6947
6948 public:
6949 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6950 _oop_cl(cm, hr, worker_id) {}
6951
6952 void do_code_blob(CodeBlob* cb) {
6953 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6954 if (nm != NULL) {
6955 nm->oops_do(&_oop_cl);
6956 }
6957 }
6958 };
6959
6960 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6961 G1CollectedHeap* _g1h;
6962 uint _worker_id;
6963
6964 public:
6965 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6966 _g1h(g1h), _worker_id(worker_id) {}
6967
6968 bool doHeapRegion(HeapRegion *hr) {
6969 HeapRegionRemSet* hrrs = hr->rem_set();
6970 if (hr->continuesHumongous()) {
6971 // Code roots should never be attached to a continuation of a humongous region
6972 assert(hrrs->strong_code_roots_list_length() == 0,
6973 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6974 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6975 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6976 hrrs->strong_code_roots_list_length()));
6977 return false;
6978 }
6979
6980 if (hr->in_collection_set()) {
6981 // Don't mark code roots into regions in the collection set here.
6982 // They will be marked when we scan them.
6983 return false;
6984 }
6985
6986 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6987 hr->strong_code_roots_do(&cb_cl);
6988 return false;
6989 }
6990 };
6991
6992 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6993 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6994 if (G1CollectedHeap::use_parallel_gc_threads()) {
6995 heap_region_par_iterate_chunked(&cl,
6996 worker_id,
6997 workers()->active_workers(),
6998 HeapRegion::ParMarkRootClaimValue);
6999 } else {
7000 heap_region_iterate(&cl);
7001 }
7002 }
7003
7004 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
7005 G1CollectedHeap* _g1h;
7006
7007 public:
7008 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7009 _g1h(g1h) {}
7010
7011 void do_code_blob(CodeBlob* cb) {
7012 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7013 if (nm == NULL) {
7014 return;
7015 }
7016
7017 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
7018 _g1h->register_nmethod(nm);
7019 }
7020 }
7021 };
7022
7023 void G1CollectedHeap::rebuild_strong_code_roots() {
7024 RebuildStrongCodeRootClosure blob_cl(this);
7025 CodeCache::blobs_do(&blob_cl);
7026 }