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