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/heapRegionSeq.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(!_free_list.is_empty(), "if the secondary_free_list was not "
527 "empty we should have moved at least one entry to the free_list");
528 HeapRegion* res = _free_list.remove_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 = _free_list.remove_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 remove_region() will check for NULL.
595 res = _free_list.remove_region(is_old);
596 } else {
597 _expand_heap_after_alloc_failure = false;
598 }
599 }
600 return res;
601 }
602
603 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
604 size_t word_size) {
605 assert(isHumongous(word_size), "word_size should be humongous");
606 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
607
608 uint first = G1_NULL_HRS_INDEX;
609 if (num_regions == 1) {
610 // Only one region to allocate, no need to go through the slower
611 // path. The caller will attempt the expansion if this fails, so
612 // let's not try to expand here too.
613 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
614 if (hr != NULL) {
615 first = hr->hrs_index();
616 } else {
617 first = G1_NULL_HRS_INDEX;
618 }
619 } else {
620 // We can't allocate humongous regions while cleanupComplete() is
621 // running, since some of the regions we find to be empty might not
622 // yet be added to the free list and it is not straightforward to
623 // know which list they are on so that we can remove them. Note
624 // that we only need to do this if we need to allocate more than
625 // one region to satisfy the current humongous allocation
626 // request. If we are only allocating one region we use the common
627 // region allocation code (see above).
628 wait_while_free_regions_coming();
629 append_secondary_free_list_if_not_empty_with_lock();
630
631 if (free_regions() >= num_regions) {
632 first = _hrs.find_contiguous(num_regions);
633 if (first != G1_NULL_HRS_INDEX) {
634 for (uint i = first; i < first + num_regions; ++i) {
635 HeapRegion* hr = region_at(i);
636 assert(hr->is_empty(), "sanity");
637 assert(is_on_master_free_list(hr), "sanity");
638 hr->set_pending_removal(true);
639 }
640 _free_list.remove_all_pending(num_regions);
641 }
642 }
643 }
644 return first;
645 }
646
647 HeapWord*
648 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
649 uint num_regions,
650 size_t word_size) {
651 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
652 assert(isHumongous(word_size), "word_size should be humongous");
653 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
654
655 // Index of last region in the series + 1.
656 uint last = first + num_regions;
657
658 // We need to initialize the region(s) we just discovered. This is
659 // a bit tricky given that it can happen concurrently with
660 // refinement threads refining cards on these regions and
661 // potentially wanting to refine the BOT as they are scanning
662 // those cards (this can happen shortly after a cleanup; see CR
663 // 6991377). So we have to set up the region(s) carefully and in
664 // a specific order.
665
666 // The word size sum of all the regions we will allocate.
667 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
668 assert(word_size <= word_size_sum, "sanity");
669
670 // This will be the "starts humongous" region.
671 HeapRegion* first_hr = region_at(first);
672 // The header of the new object will be placed at the bottom of
673 // the first region.
674 HeapWord* new_obj = first_hr->bottom();
675 // This will be the new end of the first region in the series that
676 // should also match the end of the last region in the series.
677 HeapWord* new_end = new_obj + word_size_sum;
678 // This will be the new top of the first region that will reflect
679 // this allocation.
680 HeapWord* new_top = new_obj + word_size;
681
682 // First, we need to zero the header of the space that we will be
683 // allocating. When we update top further down, some refinement
684 // threads might try to scan the region. By zeroing the header we
685 // ensure that any thread that will try to scan the region will
686 // come across the zero klass word and bail out.
687 //
688 // NOTE: It would not have been correct to have used
689 // CollectedHeap::fill_with_object() and make the space look like
690 // an int array. The thread that is doing the allocation will
691 // later update the object header to a potentially different array
692 // type and, for a very short period of time, the klass and length
693 // fields will be inconsistent. This could cause a refinement
694 // thread to calculate the object size incorrectly.
695 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
696
697 // We will set up the first region as "starts humongous". This
698 // will also update the BOT covering all the regions to reflect
699 // that there is a single object that starts at the bottom of the
700 // first region.
701 first_hr->set_startsHumongous(new_top, new_end);
702
703 // Then, if there are any, we will set up the "continues
704 // humongous" regions.
705 HeapRegion* hr = NULL;
706 for (uint i = first + 1; i < last; ++i) {
707 hr = region_at(i);
708 hr->set_continuesHumongous(first_hr);
709 }
710 // If we have "continues humongous" regions (hr != NULL), then the
711 // end of the last one should match new_end.
712 assert(hr == NULL || hr->end() == new_end, "sanity");
713
714 // Up to this point no concurrent thread would have been able to
715 // do any scanning on any region in this series. All the top
716 // fields still point to bottom, so the intersection between
717 // [bottom,top] and [card_start,card_end] will be empty. Before we
718 // update the top fields, we'll do a storestore to make sure that
719 // no thread sees the update to top before the zeroing of the
720 // object header and the BOT initialization.
721 OrderAccess::storestore();
722
723 // Now that the BOT and the object header have been initialized,
724 // we can update top of the "starts humongous" region.
725 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
726 "new_top should be in this region");
727 first_hr->set_top(new_top);
728 if (_hr_printer.is_active()) {
729 HeapWord* bottom = first_hr->bottom();
730 HeapWord* end = first_hr->orig_end();
731 if ((first + 1) == last) {
732 // the series has a single humongous region
733 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
734 } else {
735 // the series has more than one humongous regions
736 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
737 }
738 }
739
740 // Now, we will update the top fields of the "continues humongous"
741 // regions. The reason we need to do this is that, otherwise,
742 // these regions would look empty and this will confuse parts of
743 // G1. For example, the code that looks for a consecutive number
744 // of empty regions will consider them empty and try to
745 // re-allocate them. We can extend is_empty() to also include
746 // !continuesHumongous(), but it is easier to just update the top
747 // fields here. The way we set top for all regions (i.e., top ==
748 // end for all regions but the last one, top == new_top for the
749 // last one) is actually used when we will free up the humongous
750 // region in free_humongous_region().
751 hr = NULL;
752 for (uint i = first + 1; i < last; ++i) {
753 hr = region_at(i);
754 if ((i + 1) == last) {
755 // last continues humongous region
756 assert(hr->bottom() < new_top && new_top <= hr->end(),
757 "new_top should fall on this region");
758 hr->set_top(new_top);
759 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
760 } else {
761 // not last one
762 assert(new_top > hr->end(), "new_top should be above this region");
763 hr->set_top(hr->end());
764 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
765 }
766 }
767 // If we have continues humongous regions (hr != NULL), then the
768 // end of the last one should match new_end and its top should
769 // match new_top.
770 assert(hr == NULL ||
771 (hr->end() == new_end && hr->top() == new_top), "sanity");
772 check_bitmaps("Humongous Region Allocation", first_hr);
773
774 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
775 _summary_bytes_used += first_hr->used();
776 _humongous_set.add(first_hr);
777
778 return new_obj;
779 }
780
781 // If could fit into free regions w/o expansion, try.
782 // Otherwise, if can expand, do so.
783 // Otherwise, if using ex regions might help, try with ex given back.
784 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
785 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
786
787 verify_region_sets_optional();
788
789 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
790 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
791 uint x_num = expansion_regions();
792 uint fs = _hrs.free_suffix();
793 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
794 if (first == G1_NULL_HRS_INDEX) {
795 // The only thing we can do now is attempt expansion.
796 if (fs + x_num >= num_regions) {
797 // If the number of regions we're trying to allocate for this
798 // object is at most the number of regions in the free suffix,
799 // then the call to humongous_obj_allocate_find_first() above
800 // should have succeeded and we wouldn't be here.
801 //
802 // We should only be trying to expand when the free suffix is
803 // not sufficient for the object _and_ we have some expansion
804 // room available.
805 assert(num_regions > fs, "earlier allocation should have succeeded");
806
807 ergo_verbose1(ErgoHeapSizing,
808 "attempt heap expansion",
809 ergo_format_reason("humongous allocation request failed")
810 ergo_format_byte("allocation request"),
811 word_size * HeapWordSize);
812 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
813 // Even though the heap was expanded, it might not have
814 // reached the desired size. So, we cannot assume that the
815 // allocation will succeed.
816 first = humongous_obj_allocate_find_first(num_regions, word_size);
817 }
818 }
819 }
820
821 HeapWord* result = NULL;
822 if (first != G1_NULL_HRS_INDEX) {
823 result =
824 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
825 assert(result != NULL, "it should always return a valid result");
826
827 // A successful humongous object allocation changes the used space
828 // information of the old generation so we need to recalculate the
829 // sizes and update the jstat counters here.
830 g1mm()->update_sizes();
831 }
832
833 verify_region_sets_optional();
834
835 return result;
836 }
837
838 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
839 assert_heap_not_locked_and_not_at_safepoint();
840 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
841
842 unsigned int dummy_gc_count_before;
843 int dummy_gclocker_retry_count = 0;
844 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
845 }
846
847 HeapWord*
848 G1CollectedHeap::mem_allocate(size_t word_size,
849 bool* gc_overhead_limit_was_exceeded) {
850 assert_heap_not_locked_and_not_at_safepoint();
851
852 // Loop until the allocation is satisfied, or unsatisfied after GC.
853 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
854 unsigned int gc_count_before;
855
856 HeapWord* result = NULL;
857 if (!isHumongous(word_size)) {
858 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
859 } else {
860 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
861 }
862 if (result != NULL) {
863 return result;
864 }
865
866 // Create the garbage collection operation...
867 VM_G1CollectForAllocation op(gc_count_before, word_size);
868 // ...and get the VM thread to execute it.
869 VMThread::execute(&op);
870
871 if (op.prologue_succeeded() && op.pause_succeeded()) {
872 // If the operation was successful we'll return the result even
873 // if it is NULL. If the allocation attempt failed immediately
874 // after a Full GC, it's unlikely we'll be able to allocate now.
875 HeapWord* result = op.result();
876 if (result != NULL && !isHumongous(word_size)) {
877 // Allocations that take place on VM operations do not do any
878 // card dirtying and we have to do it here. We only have to do
879 // this for non-humongous allocations, though.
880 dirty_young_block(result, word_size);
881 }
882 return result;
883 } else {
884 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
885 return NULL;
886 }
887 assert(op.result() == NULL,
888 "the result should be NULL if the VM op did not succeed");
889 }
890
891 // Give a warning if we seem to be looping forever.
892 if ((QueuedAllocationWarningCount > 0) &&
893 (try_count % QueuedAllocationWarningCount == 0)) {
894 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
895 }
896 }
897
898 ShouldNotReachHere();
899 return NULL;
900 }
901
902 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
903 unsigned int *gc_count_before_ret,
904 int* gclocker_retry_count_ret) {
905 // Make sure you read the note in attempt_allocation_humongous().
906
907 assert_heap_not_locked_and_not_at_safepoint();
908 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
909 "be called for humongous allocation requests");
910
911 // We should only get here after the first-level allocation attempt
912 // (attempt_allocation()) failed to allocate.
913
914 // We will loop until a) we manage to successfully perform the
915 // allocation or b) we successfully schedule a collection which
916 // fails to perform the allocation. b) is the only case when we'll
917 // return NULL.
918 HeapWord* result = NULL;
919 for (int try_count = 1; /* we'll return */; try_count += 1) {
920 bool should_try_gc;
921 unsigned int gc_count_before;
922
923 {
924 MutexLockerEx x(Heap_lock);
925
926 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
927 false /* bot_updates */);
928 if (result != NULL) {
929 return result;
930 }
931
932 // If we reach here, attempt_allocation_locked() above failed to
933 // allocate a new region. So the mutator alloc region should be NULL.
934 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
935
936 if (GC_locker::is_active_and_needs_gc()) {
937 if (g1_policy()->can_expand_young_list()) {
938 // No need for an ergo verbose message here,
939 // can_expand_young_list() does this when it returns true.
940 result = _mutator_alloc_region.attempt_allocation_force(word_size,
941 false /* bot_updates */);
942 if (result != NULL) {
943 return result;
944 }
945 }
946 should_try_gc = false;
947 } else {
948 // The GCLocker may not be active but the GCLocker initiated
949 // GC may not yet have been performed (GCLocker::needs_gc()
950 // returns true). In this case we do not try this GC and
951 // wait until the GCLocker initiated GC is performed, and
952 // then retry the allocation.
953 if (GC_locker::needs_gc()) {
954 should_try_gc = false;
955 } else {
956 // Read the GC count while still holding the Heap_lock.
957 gc_count_before = total_collections();
958 should_try_gc = true;
959 }
960 }
961 }
962
963 if (should_try_gc) {
964 bool succeeded;
965 result = do_collection_pause(word_size, gc_count_before, &succeeded,
966 GCCause::_g1_inc_collection_pause);
967 if (result != NULL) {
968 assert(succeeded, "only way to get back a non-NULL result");
969 return result;
970 }
971
972 if (succeeded) {
973 // If we get here we successfully scheduled a collection which
974 // failed to allocate. No point in trying to allocate
975 // further. We'll just return NULL.
976 MutexLockerEx x(Heap_lock);
977 *gc_count_before_ret = total_collections();
978 return NULL;
979 }
980 } else {
981 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
982 MutexLockerEx x(Heap_lock);
983 *gc_count_before_ret = total_collections();
984 return NULL;
985 }
986 // The GCLocker is either active or the GCLocker initiated
987 // GC has not yet been performed. Stall until it is and
988 // then retry the allocation.
989 GC_locker::stall_until_clear();
990 (*gclocker_retry_count_ret) += 1;
991 }
992
993 // We can reach here if we were unsuccessful in scheduling a
994 // collection (because another thread beat us to it) or if we were
995 // stalled due to the GC locker. In either can we should retry the
996 // allocation attempt in case another thread successfully
997 // performed a collection and reclaimed enough space. We do the
998 // first attempt (without holding the Heap_lock) here and the
999 // follow-on attempt will be at the start of the next loop
1000 // iteration (after taking the Heap_lock).
1001 result = _mutator_alloc_region.attempt_allocation(word_size,
1002 false /* bot_updates */);
1003 if (result != NULL) {
1004 return result;
1005 }
1006
1007 // Give a warning if we seem to be looping forever.
1008 if ((QueuedAllocationWarningCount > 0) &&
1009 (try_count % QueuedAllocationWarningCount == 0)) {
1010 warning("G1CollectedHeap::attempt_allocation_slow() "
1011 "retries %d times", try_count);
1012 }
1013 }
1014
1015 ShouldNotReachHere();
1016 return NULL;
1017 }
1018
1019 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1020 unsigned int * gc_count_before_ret,
1021 int* gclocker_retry_count_ret) {
1022 // The structure of this method has a lot of similarities to
1023 // attempt_allocation_slow(). The reason these two were not merged
1024 // into a single one is that such a method would require several "if
1025 // allocation is not humongous do this, otherwise do that"
1026 // conditional paths which would obscure its flow. In fact, an early
1027 // version of this code did use a unified method which was harder to
1028 // follow and, as a result, it had subtle bugs that were hard to
1029 // track down. So keeping these two methods separate allows each to
1030 // be more readable. It will be good to keep these two in sync as
1031 // much as possible.
1032
1033 assert_heap_not_locked_and_not_at_safepoint();
1034 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1035 "should only be called for humongous allocations");
1036
1037 // Humongous objects can exhaust the heap quickly, so we should check if we
1038 // need to start a marking cycle at each humongous object allocation. We do
1039 // the check before we do the actual allocation. The reason for doing it
1040 // before the allocation is that we avoid having to keep track of the newly
1041 // allocated memory while we do a GC.
1042 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1043 word_size)) {
1044 collect(GCCause::_g1_humongous_allocation);
1045 }
1046
1047 // We will loop until a) we manage to successfully perform the
1048 // allocation or b) we successfully schedule a collection which
1049 // fails to perform the allocation. b) is the only case when we'll
1050 // return NULL.
1051 HeapWord* result = NULL;
1052 for (int try_count = 1; /* we'll return */; try_count += 1) {
1053 bool should_try_gc;
1054 unsigned int gc_count_before;
1055
1056 {
1057 MutexLockerEx x(Heap_lock);
1058
1059 // Given that humongous objects are not allocated in young
1060 // regions, we'll first try to do the allocation without doing a
1061 // collection hoping that there's enough space in the heap.
1062 result = humongous_obj_allocate(word_size);
1063 if (result != NULL) {
1064 return result;
1065 }
1066
1067 if (GC_locker::is_active_and_needs_gc()) {
1068 should_try_gc = false;
1069 } else {
1070 // The GCLocker may not be active but the GCLocker initiated
1071 // GC may not yet have been performed (GCLocker::needs_gc()
1072 // returns true). In this case we do not try this GC and
1073 // wait until the GCLocker initiated GC is performed, and
1074 // then retry the allocation.
1075 if (GC_locker::needs_gc()) {
1076 should_try_gc = false;
1077 } else {
1078 // Read the GC count while still holding the Heap_lock.
1079 gc_count_before = total_collections();
1080 should_try_gc = true;
1081 }
1082 }
1083 }
1084
1085 if (should_try_gc) {
1086 // If we failed to allocate the humongous object, we should try to
1087 // do a collection pause (if we're allowed) in case it reclaims
1088 // enough space for the allocation to succeed after the pause.
1089
1090 bool succeeded;
1091 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1092 GCCause::_g1_humongous_allocation);
1093 if (result != NULL) {
1094 assert(succeeded, "only way to get back a non-NULL result");
1095 return result;
1096 }
1097
1098 if (succeeded) {
1099 // If we get here we successfully scheduled a collection which
1100 // failed to allocate. No point in trying to allocate
1101 // further. We'll just return NULL.
1102 MutexLockerEx x(Heap_lock);
1103 *gc_count_before_ret = total_collections();
1104 return NULL;
1105 }
1106 } else {
1107 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1108 MutexLockerEx x(Heap_lock);
1109 *gc_count_before_ret = total_collections();
1110 return NULL;
1111 }
1112 // The GCLocker is either active or the GCLocker initiated
1113 // GC has not yet been performed. Stall until it is and
1114 // then retry the allocation.
1115 GC_locker::stall_until_clear();
1116 (*gclocker_retry_count_ret) += 1;
1117 }
1118
1119 // We can reach here if we were unsuccessful in scheduling a
1120 // collection (because another thread beat us to it) or if we were
1121 // stalled due to the GC locker. In either can we should retry the
1122 // allocation attempt in case another thread successfully
1123 // performed a collection and reclaimed enough space. Give a
1124 // warning if we seem to be looping forever.
1125
1126 if ((QueuedAllocationWarningCount > 0) &&
1127 (try_count % QueuedAllocationWarningCount == 0)) {
1128 warning("G1CollectedHeap::attempt_allocation_humongous() "
1129 "retries %d times", try_count);
1130 }
1131 }
1132
1133 ShouldNotReachHere();
1134 return NULL;
1135 }
1136
1137 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1138 bool expect_null_mutator_alloc_region) {
1139 assert_at_safepoint(true /* should_be_vm_thread */);
1140 assert(_mutator_alloc_region.get() == NULL ||
1141 !expect_null_mutator_alloc_region,
1142 "the current alloc region was unexpectedly found to be non-NULL");
1143
1144 if (!isHumongous(word_size)) {
1145 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1146 false /* bot_updates */);
1147 } else {
1148 HeapWord* result = humongous_obj_allocate(word_size);
1149 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1150 g1_policy()->set_initiate_conc_mark_if_possible();
1151 }
1152 return result;
1153 }
1154
1155 ShouldNotReachHere();
1156 }
1157
1158 class PostMCRemSetClearClosure: public HeapRegionClosure {
1159 G1CollectedHeap* _g1h;
1160 ModRefBarrierSet* _mr_bs;
1161 public:
1162 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1163 _g1h(g1h), _mr_bs(mr_bs) {}
1164
1165 bool doHeapRegion(HeapRegion* r) {
1166 HeapRegionRemSet* hrrs = r->rem_set();
1167
1168 if (r->continuesHumongous()) {
1169 // We'll assert that the strong code root list and RSet is empty
1170 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1171 assert(hrrs->occupied() == 0, "RSet should be empty");
1172 return false;
1173 }
1174
1175 _g1h->reset_gc_time_stamps(r);
1176 hrrs->clear();
1177 // You might think here that we could clear just the cards
1178 // corresponding to the used region. But no: if we leave a dirty card
1179 // in a region we might allocate into, then it would prevent that card
1180 // from being enqueued, and cause it to be missed.
1181 // Re: the performance cost: we shouldn't be doing full GC anyway!
1182 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1183
1184 return false;
1185 }
1186 };
1187
1188 void G1CollectedHeap::clear_rsets_post_compaction() {
1189 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1190 heap_region_iterate(&rs_clear);
1191 }
1192
1193 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1194 G1CollectedHeap* _g1h;
1195 UpdateRSOopClosure _cl;
1196 int _worker_i;
1197 public:
1198 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1199 _cl(g1->g1_rem_set(), worker_i),
1200 _worker_i(worker_i),
1201 _g1h(g1)
1202 { }
1203
1204 bool doHeapRegion(HeapRegion* r) {
1205 if (!r->continuesHumongous()) {
1206 _cl.set_from(r);
1207 r->oop_iterate(&_cl);
1208 }
1209 return false;
1210 }
1211 };
1212
1213 class ParRebuildRSTask: public AbstractGangTask {
1214 G1CollectedHeap* _g1;
1215 public:
1216 ParRebuildRSTask(G1CollectedHeap* g1)
1217 : AbstractGangTask("ParRebuildRSTask"),
1218 _g1(g1)
1219 { }
1220
1221 void work(uint worker_id) {
1222 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1223 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1224 _g1->workers()->active_workers(),
1225 HeapRegion::RebuildRSClaimValue);
1226 }
1227 };
1228
1229 class PostCompactionPrinterClosure: public HeapRegionClosure {
1230 private:
1231 G1HRPrinter* _hr_printer;
1232 public:
1233 bool doHeapRegion(HeapRegion* hr) {
1234 assert(!hr->is_young(), "not expecting to find young regions");
1235 // We only generate output for non-empty regions.
1236 if (!hr->is_empty()) {
1237 if (!hr->isHumongous()) {
1238 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1239 } else if (hr->startsHumongous()) {
1240 if (hr->region_num() == 1) {
1241 // single humongous region
1242 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1243 } else {
1244 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1245 }
1246 } else {
1247 assert(hr->continuesHumongous(), "only way to get here");
1248 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1249 }
1250 }
1251 return false;
1252 }
1253
1254 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1255 : _hr_printer(hr_printer) { }
1256 };
1257
1258 void G1CollectedHeap::print_hrs_post_compaction() {
1259 PostCompactionPrinterClosure cl(hr_printer());
1260 heap_region_iterate(&cl);
1261 }
1262
1263 bool G1CollectedHeap::do_collection(bool explicit_gc,
1264 bool clear_all_soft_refs,
1265 size_t word_size) {
1266 assert_at_safepoint(true /* should_be_vm_thread */);
1267
1268 if (GC_locker::check_active_before_gc()) {
1269 return false;
1270 }
1271
1272 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1273 gc_timer->register_gc_start();
1274
1275 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1276 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1277
1278 SvcGCMarker sgcm(SvcGCMarker::FULL);
1279 ResourceMark rm;
1280
1281 print_heap_before_gc();
1282 trace_heap_before_gc(gc_tracer);
1283
1284 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1285
1286 verify_region_sets_optional();
1287
1288 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1289 collector_policy()->should_clear_all_soft_refs();
1290
1291 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1292
1293 {
1294 IsGCActiveMark x;
1295
1296 // Timing
1297 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1298 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1299 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1300
1301 {
1302 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1303 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1304 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1305
1306 double start = os::elapsedTime();
1307 g1_policy()->record_full_collection_start();
1308
1309 // Note: When we have a more flexible GC logging framework that
1310 // allows us to add optional attributes to a GC log record we
1311 // could consider timing and reporting how long we wait in the
1312 // following two methods.
1313 wait_while_free_regions_coming();
1314 // If we start the compaction before the CM threads finish
1315 // scanning the root regions we might trip them over as we'll
1316 // be moving objects / updating references. So let's wait until
1317 // they are done. By telling them to abort, they should complete
1318 // early.
1319 _cm->root_regions()->abort();
1320 _cm->root_regions()->wait_until_scan_finished();
1321 append_secondary_free_list_if_not_empty_with_lock();
1322
1323 gc_prologue(true);
1324 increment_total_collections(true /* full gc */);
1325 increment_old_marking_cycles_started();
1326
1327 assert(used() == recalculate_used(), "Should be equal");
1328
1329 verify_before_gc();
1330
1331 check_bitmaps("Full GC Start");
1332 pre_full_gc_dump(gc_timer);
1333
1334 COMPILER2_PRESENT(DerivedPointerTable::clear());
1335
1336 // Disable discovery and empty the discovered lists
1337 // for the CM ref processor.
1338 ref_processor_cm()->disable_discovery();
1339 ref_processor_cm()->abandon_partial_discovery();
1340 ref_processor_cm()->verify_no_references_recorded();
1341
1342 // Abandon current iterations of concurrent marking and concurrent
1343 // refinement, if any are in progress. We have to do this before
1344 // wait_until_scan_finished() below.
1345 concurrent_mark()->abort();
1346
1347 // Make sure we'll choose a new allocation region afterwards.
1348 release_mutator_alloc_region();
1349 abandon_gc_alloc_regions();
1350 g1_rem_set()->cleanupHRRS();
1351
1352 // We should call this after we retire any currently active alloc
1353 // regions so that all the ALLOC / RETIRE events are generated
1354 // before the start GC event.
1355 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1356
1357 // We may have added regions to the current incremental collection
1358 // set between the last GC or pause and now. We need to clear the
1359 // incremental collection set and then start rebuilding it afresh
1360 // after this full GC.
1361 abandon_collection_set(g1_policy()->inc_cset_head());
1362 g1_policy()->clear_incremental_cset();
1363 g1_policy()->stop_incremental_cset_building();
1364
1365 tear_down_region_sets(false /* free_list_only */);
1366 g1_policy()->set_gcs_are_young(true);
1367
1368 // See the comments in g1CollectedHeap.hpp and
1369 // G1CollectedHeap::ref_processing_init() about
1370 // how reference processing currently works in G1.
1371
1372 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1373 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1374
1375 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1376 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1377
1378 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1379 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1380
1381 // Do collection work
1382 {
1383 HandleMark hm; // Discard invalid handles created during gc
1384 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1385 }
1386
1387 assert(free_regions() == 0, "we should not have added any free regions");
1388 rebuild_region_sets(false /* free_list_only */);
1389
1390 // Enqueue any discovered reference objects that have
1391 // not been removed from the discovered lists.
1392 ref_processor_stw()->enqueue_discovered_references();
1393
1394 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1395
1396 MemoryService::track_memory_usage();
1397
1398 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1399 ref_processor_stw()->verify_no_references_recorded();
1400
1401 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1402 ClassLoaderDataGraph::purge();
1403 MetaspaceAux::verify_metrics();
1404
1405 // Note: since we've just done a full GC, concurrent
1406 // marking is no longer active. Therefore we need not
1407 // re-enable reference discovery for the CM ref processor.
1408 // That will be done at the start of the next marking cycle.
1409 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1410 ref_processor_cm()->verify_no_references_recorded();
1411
1412 reset_gc_time_stamp();
1413 // Since everything potentially moved, we will clear all remembered
1414 // sets, and clear all cards. Later we will rebuild remembered
1415 // sets. We will also reset the GC time stamps of the regions.
1416 clear_rsets_post_compaction();
1417 check_gc_time_stamps();
1418
1419 // Resize the heap if necessary.
1420 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1421
1422 if (_hr_printer.is_active()) {
1423 // We should do this after we potentially resize the heap so
1424 // that all the COMMIT / UNCOMMIT events are generated before
1425 // the end GC event.
1426
1427 print_hrs_post_compaction();
1428 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1429 }
1430
1431 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1432 if (hot_card_cache->use_cache()) {
1433 hot_card_cache->reset_card_counts();
1434 hot_card_cache->reset_hot_cache();
1435 }
1436
1437 // Rebuild remembered sets of all regions.
1438 if (G1CollectedHeap::use_parallel_gc_threads()) {
1439 uint n_workers =
1440 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1441 workers()->active_workers(),
1442 Threads::number_of_non_daemon_threads());
1443 assert(UseDynamicNumberOfGCThreads ||
1444 n_workers == workers()->total_workers(),
1445 "If not dynamic should be using all the workers");
1446 workers()->set_active_workers(n_workers);
1447 // Set parallel threads in the heap (_n_par_threads) only
1448 // before a parallel phase and always reset it to 0 after
1449 // the phase so that the number of parallel threads does
1450 // no get carried forward to a serial phase where there
1451 // may be code that is "possibly_parallel".
1452 set_par_threads(n_workers);
1453
1454 ParRebuildRSTask rebuild_rs_task(this);
1455 assert(check_heap_region_claim_values(
1456 HeapRegion::InitialClaimValue), "sanity check");
1457 assert(UseDynamicNumberOfGCThreads ||
1458 workers()->active_workers() == workers()->total_workers(),
1459 "Unless dynamic should use total workers");
1460 // Use the most recent number of active workers
1461 assert(workers()->active_workers() > 0,
1462 "Active workers not properly set");
1463 set_par_threads(workers()->active_workers());
1464 workers()->run_task(&rebuild_rs_task);
1465 set_par_threads(0);
1466 assert(check_heap_region_claim_values(
1467 HeapRegion::RebuildRSClaimValue), "sanity check");
1468 reset_heap_region_claim_values();
1469 } else {
1470 RebuildRSOutOfRegionClosure rebuild_rs(this);
1471 heap_region_iterate(&rebuild_rs);
1472 }
1473
1474 // Rebuild the strong code root lists for each region
1475 rebuild_strong_code_roots();
1476
1477 if (true) { // FIXME
1478 MetaspaceGC::compute_new_size();
1479 }
1480
1481 #ifdef TRACESPINNING
1482 ParallelTaskTerminator::print_termination_counts();
1483 #endif
1484
1485 // Discard all rset updates
1486 JavaThread::dirty_card_queue_set().abandon_logs();
1487 assert(!G1DeferredRSUpdate
1488 || (G1DeferredRSUpdate &&
1489 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1490
1491 _young_list->reset_sampled_info();
1492 // At this point there should be no regions in the
1493 // entire heap tagged as young.
1494 assert(check_young_list_empty(true /* check_heap */),
1495 "young list should be empty at this point");
1496
1497 // Update the number of full collections that have been completed.
1498 increment_old_marking_cycles_completed(false /* concurrent */);
1499
1500 _hrs.verify_optional();
1501 verify_region_sets_optional();
1502
1503 verify_after_gc();
1504
1505 // Clear the previous marking bitmap, if needed for bitmap verification.
1506 // Note we cannot do this when we clear the next marking bitmap in
1507 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1508 // objects marked during a full GC against the previous bitmap.
1509 // But we need to clear it before calling check_bitmaps below since
1510 // the full GC has compacted objects and updated TAMS but not updated
1511 // the prev bitmap.
1512 if (G1VerifyBitmaps) {
1513 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1514 }
1515 check_bitmaps("Full GC End");
1516
1517 // Start a new incremental collection set for the next pause
1518 assert(g1_policy()->collection_set() == NULL, "must be");
1519 g1_policy()->start_incremental_cset_building();
1520
1521 clear_cset_fast_test();
1522
1523 init_mutator_alloc_region();
1524
1525 double end = os::elapsedTime();
1526 g1_policy()->record_full_collection_end();
1527
1528 if (G1Log::fine()) {
1529 g1_policy()->print_heap_transition();
1530 }
1531
1532 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1533 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1534 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1535 // before any GC notifications are raised.
1536 g1mm()->update_sizes();
1537
1538 gc_epilogue(true);
1539 }
1540
1541 if (G1Log::finer()) {
1542 g1_policy()->print_detailed_heap_transition(true /* full */);
1543 }
1544
1545 print_heap_after_gc();
1546 trace_heap_after_gc(gc_tracer);
1547
1548 post_full_gc_dump(gc_timer);
1549
1550 gc_timer->register_gc_end();
1551 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1552 }
1553
1554 return true;
1555 }
1556
1557 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1558 // do_collection() will return whether it succeeded in performing
1559 // the GC. Currently, there is no facility on the
1560 // do_full_collection() API to notify the caller than the collection
1561 // did not succeed (e.g., because it was locked out by the GC
1562 // locker). So, right now, we'll ignore the return value.
1563 bool dummy = do_collection(true, /* explicit_gc */
1564 clear_all_soft_refs,
1565 0 /* word_size */);
1566 }
1567
1568 // This code is mostly copied from TenuredGeneration.
1569 void
1570 G1CollectedHeap::
1571 resize_if_necessary_after_full_collection(size_t word_size) {
1572 // Include the current allocation, if any, and bytes that will be
1573 // pre-allocated to support collections, as "used".
1574 const size_t used_after_gc = used();
1575 const size_t capacity_after_gc = capacity();
1576 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1577
1578 // This is enforced in arguments.cpp.
1579 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1580 "otherwise the code below doesn't make sense");
1581
1582 // We don't have floating point command-line arguments
1583 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1584 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1585 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1586 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1587
1588 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1589 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1590
1591 // We have to be careful here as these two calculations can overflow
1592 // 32-bit size_t's.
1593 double used_after_gc_d = (double) used_after_gc;
1594 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1595 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1596
1597 // Let's make sure that they are both under the max heap size, which
1598 // by default will make them fit into a size_t.
1599 double desired_capacity_upper_bound = (double) max_heap_size;
1600 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1601 desired_capacity_upper_bound);
1602 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1603 desired_capacity_upper_bound);
1604
1605 // We can now safely turn them into size_t's.
1606 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1607 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1608
1609 // This assert only makes sense here, before we adjust them
1610 // with respect to the min and max heap size.
1611 assert(minimum_desired_capacity <= maximum_desired_capacity,
1612 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1613 "maximum_desired_capacity = "SIZE_FORMAT,
1614 minimum_desired_capacity, maximum_desired_capacity));
1615
1616 // Should not be greater than the heap max size. No need to adjust
1617 // it with respect to the heap min size as it's a lower bound (i.e.,
1618 // we'll try to make the capacity larger than it, not smaller).
1619 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1620 // Should not be less than the heap min size. No need to adjust it
1621 // with respect to the heap max size as it's an upper bound (i.e.,
1622 // we'll try to make the capacity smaller than it, not greater).
1623 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1624
1625 if (capacity_after_gc < minimum_desired_capacity) {
1626 // Don't expand unless it's significant
1627 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1628 ergo_verbose4(ErgoHeapSizing,
1629 "attempt heap expansion",
1630 ergo_format_reason("capacity lower than "
1631 "min desired capacity after Full GC")
1632 ergo_format_byte("capacity")
1633 ergo_format_byte("occupancy")
1634 ergo_format_byte_perc("min desired capacity"),
1635 capacity_after_gc, used_after_gc,
1636 minimum_desired_capacity, (double) MinHeapFreeRatio);
1637 expand(expand_bytes);
1638
1639 // No expansion, now see if we want to shrink
1640 } else if (capacity_after_gc > maximum_desired_capacity) {
1641 // Capacity too large, compute shrinking size
1642 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1643 ergo_verbose4(ErgoHeapSizing,
1644 "attempt heap shrinking",
1645 ergo_format_reason("capacity higher than "
1646 "max desired capacity after Full GC")
1647 ergo_format_byte("capacity")
1648 ergo_format_byte("occupancy")
1649 ergo_format_byte_perc("max desired capacity"),
1650 capacity_after_gc, used_after_gc,
1651 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1652 shrink(shrink_bytes);
1653 }
1654 }
1655
1656
1657 HeapWord*
1658 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1659 bool* succeeded) {
1660 assert_at_safepoint(true /* should_be_vm_thread */);
1661
1662 *succeeded = true;
1663 // Let's attempt the allocation first.
1664 HeapWord* result =
1665 attempt_allocation_at_safepoint(word_size,
1666 false /* expect_null_mutator_alloc_region */);
1667 if (result != NULL) {
1668 assert(*succeeded, "sanity");
1669 return result;
1670 }
1671
1672 // In a G1 heap, we're supposed to keep allocation from failing by
1673 // incremental pauses. Therefore, at least for now, we'll favor
1674 // expansion over collection. (This might change in the future if we can
1675 // do something smarter than full collection to satisfy a failed alloc.)
1676 result = expand_and_allocate(word_size);
1677 if (result != NULL) {
1678 assert(*succeeded, "sanity");
1679 return result;
1680 }
1681
1682 // Expansion didn't work, we'll try to do a Full GC.
1683 bool gc_succeeded = do_collection(false, /* explicit_gc */
1684 false, /* clear_all_soft_refs */
1685 word_size);
1686 if (!gc_succeeded) {
1687 *succeeded = false;
1688 return NULL;
1689 }
1690
1691 // Retry the allocation
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 // Then, try a Full GC that will collect all soft references.
1700 gc_succeeded = do_collection(false, /* explicit_gc */
1701 true, /* clear_all_soft_refs */
1702 word_size);
1703 if (!gc_succeeded) {
1704 *succeeded = false;
1705 return NULL;
1706 }
1707
1708 // Retry the allocation once more
1709 result = attempt_allocation_at_safepoint(word_size,
1710 true /* expect_null_mutator_alloc_region */);
1711 if (result != NULL) {
1712 assert(*succeeded, "sanity");
1713 return result;
1714 }
1715
1716 assert(!collector_policy()->should_clear_all_soft_refs(),
1717 "Flag should have been handled and cleared prior to this point");
1718
1719 // What else? We might try synchronous finalization later. If the total
1720 // space available is large enough for the allocation, then a more
1721 // complete compaction phase than we've tried so far might be
1722 // appropriate.
1723 assert(*succeeded, "sanity");
1724 return NULL;
1725 }
1726
1727 // Attempting to expand the heap sufficiently
1728 // to support an allocation of the given "word_size". If
1729 // successful, perform the allocation and return the address of the
1730 // allocated block, or else "NULL".
1731
1732 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1733 assert_at_safepoint(true /* should_be_vm_thread */);
1734
1735 verify_region_sets_optional();
1736
1737 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1738 ergo_verbose1(ErgoHeapSizing,
1739 "attempt heap expansion",
1740 ergo_format_reason("allocation request failed")
1741 ergo_format_byte("allocation request"),
1742 word_size * HeapWordSize);
1743 if (expand(expand_bytes)) {
1744 _hrs.verify_optional();
1745 verify_region_sets_optional();
1746 return attempt_allocation_at_safepoint(word_size,
1747 false /* expect_null_mutator_alloc_region */);
1748 }
1749 return NULL;
1750 }
1751
1752 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1753 HeapWord* new_end) {
1754 assert(old_end != new_end, "don't call this otherwise");
1755 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1756
1757 // Update the committed mem region.
1758 _g1_committed.set_end(new_end);
1759 // Tell the card table about the update.
1760 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1761 // Tell the BOT about the update.
1762 _bot_shared->resize(_g1_committed.word_size());
1763 // Tell the hot card cache about the update
1764 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1765 }
1766
1767 bool G1CollectedHeap::expand(size_t expand_bytes) {
1768 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1769 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1770 HeapRegion::GrainBytes);
1771 ergo_verbose2(ErgoHeapSizing,
1772 "expand the heap",
1773 ergo_format_byte("requested expansion amount")
1774 ergo_format_byte("attempted expansion amount"),
1775 expand_bytes, aligned_expand_bytes);
1776
1777 if (_g1_storage.uncommitted_size() == 0) {
1778 ergo_verbose0(ErgoHeapSizing,
1779 "did not expand the heap",
1780 ergo_format_reason("heap already fully expanded"));
1781 return false;
1782 }
1783
1784 // First commit the memory.
1785 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1786 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1787 if (successful) {
1788 // Then propagate this update to the necessary data structures.
1789 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1790 update_committed_space(old_end, new_end);
1791
1792 FreeRegionList expansion_list("Local Expansion List");
1793 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1794 assert(mr.start() == old_end, "post-condition");
1795 // mr might be a smaller region than what was requested if
1796 // expand_by() was unable to allocate the HeapRegion instances
1797 assert(mr.end() <= new_end, "post-condition");
1798
1799 size_t actual_expand_bytes = mr.byte_size();
1800 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1801 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1802 "post-condition");
1803 if (actual_expand_bytes < aligned_expand_bytes) {
1804 // We could not expand _hrs to the desired size. In this case we
1805 // need to shrink the committed space accordingly.
1806 assert(mr.end() < new_end, "invariant");
1807
1808 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1809 // First uncommit the memory.
1810 _g1_storage.shrink_by(diff_bytes);
1811 // Then propagate this update to the necessary data structures.
1812 update_committed_space(new_end, mr.end());
1813 }
1814 _free_list.add_as_tail(&expansion_list);
1815
1816 if (_hr_printer.is_active()) {
1817 HeapWord* curr = mr.start();
1818 while (curr < mr.end()) {
1819 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1820 _hr_printer.commit(curr, curr_end);
1821 curr = curr_end;
1822 }
1823 assert(curr == mr.end(), "post-condition");
1824 }
1825 g1_policy()->record_new_heap_size(n_regions());
1826 } else {
1827 ergo_verbose0(ErgoHeapSizing,
1828 "did not expand the heap",
1829 ergo_format_reason("heap expansion operation failed"));
1830 // The expansion of the virtual storage space was unsuccessful.
1831 // Let's see if it was because we ran out of swap.
1832 if (G1ExitOnExpansionFailure &&
1833 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1834 // We had head room...
1835 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1836 }
1837 }
1838 return successful;
1839 }
1840
1841 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1842 size_t aligned_shrink_bytes =
1843 ReservedSpace::page_align_size_down(shrink_bytes);
1844 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1845 HeapRegion::GrainBytes);
1846 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1847
1848 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1849 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1850 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1851
1852 ergo_verbose3(ErgoHeapSizing,
1853 "shrink the heap",
1854 ergo_format_byte("requested shrinking amount")
1855 ergo_format_byte("aligned shrinking amount")
1856 ergo_format_byte("attempted shrinking amount"),
1857 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1858 if (num_regions_removed > 0) {
1859 _g1_storage.shrink_by(shrunk_bytes);
1860 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1861
1862 if (_hr_printer.is_active()) {
1863 HeapWord* curr = old_end;
1864 while (curr > new_end) {
1865 HeapWord* curr_end = curr;
1866 curr -= HeapRegion::GrainWords;
1867 _hr_printer.uncommit(curr, curr_end);
1868 }
1869 }
1870
1871 _expansion_regions += num_regions_removed;
1872 update_committed_space(old_end, new_end);
1873 HeapRegionRemSet::shrink_heap(n_regions());
1874 g1_policy()->record_new_heap_size(n_regions());
1875 } else {
1876 ergo_verbose0(ErgoHeapSizing,
1877 "did not shrink the heap",
1878 ergo_format_reason("heap shrinking operation failed"));
1879 }
1880 }
1881
1882 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1883 verify_region_sets_optional();
1884
1885 // We should only reach here at the end of a Full GC which means we
1886 // should not not be holding to any GC alloc regions. The method
1887 // below will make sure of that and do any remaining clean up.
1888 abandon_gc_alloc_regions();
1889
1890 // Instead of tearing down / rebuilding the free lists here, we
1891 // could instead use the remove_all_pending() method on free_list to
1892 // remove only the ones that we need to remove.
1893 tear_down_region_sets(true /* free_list_only */);
1894 shrink_helper(shrink_bytes);
1895 rebuild_region_sets(true /* free_list_only */);
1896
1897 _hrs.verify_optional();
1898 verify_region_sets_optional();
1899 }
1900
1901 // Public methods.
1902
1903 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1904 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1905 #endif // _MSC_VER
1906
1907
1908 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1909 SharedHeap(policy_),
1910 _g1_policy(policy_),
1911 _dirty_card_queue_set(false),
1912 _into_cset_dirty_card_queue_set(false),
1913 _is_alive_closure_cm(this),
1914 _is_alive_closure_stw(this),
1915 _ref_processor_cm(NULL),
1916 _ref_processor_stw(NULL),
1917 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1918 _bot_shared(NULL),
1919 _evac_failure_scan_stack(NULL),
1920 _mark_in_progress(false),
1921 _cg1r(NULL), _summary_bytes_used(0),
1922 _g1mm(NULL),
1923 _refine_cte_cl(NULL),
1924 _full_collection(false),
1925 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1926 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1927 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1928 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1929 _free_regions_coming(false),
1930 _young_list(new YoungList(this)),
1931 _gc_time_stamp(0),
1932 _retained_old_gc_alloc_region(NULL),
1933 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1934 _old_plab_stats(OldPLABSize, PLABWeight),
1935 _expand_heap_after_alloc_failure(true),
1936 _surviving_young_words(NULL),
1937 _old_marking_cycles_started(0),
1938 _old_marking_cycles_completed(0),
1939 _concurrent_cycle_started(false),
1940 _in_cset_fast_test(),
1941 _dirty_cards_region_list(NULL),
1942 _worker_cset_start_region(NULL),
1943 _worker_cset_start_region_time_stamp(NULL),
1944 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1945 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1946 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1947 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1948
1949 _g1h = this;
1950 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1951 vm_exit_during_initialization("Failed necessary allocation.");
1952 }
1953
1954 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1955
1956 int n_queues = MAX2((int)ParallelGCThreads, 1);
1957 _task_queues = new RefToScanQueueSet(n_queues);
1958
1959 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1960 assert(n_rem_sets > 0, "Invariant.");
1961
1962 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1963 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1964 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1965
1966 for (int i = 0; i < n_queues; i++) {
1967 RefToScanQueue* q = new RefToScanQueue();
1968 q->initialize();
1969 _task_queues->register_queue(i, q);
1970 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1971 }
1972 clear_cset_start_regions();
1973
1974 // Initialize the G1EvacuationFailureALot counters and flags.
1975 NOT_PRODUCT(reset_evacuation_should_fail();)
1976
1977 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1978 }
1979
1980 jint G1CollectedHeap::initialize() {
1981 CollectedHeap::pre_initialize();
1982 os::enable_vtime();
1983
1984 G1Log::init();
1985
1986 // Necessary to satisfy locking discipline assertions.
1987
1988 MutexLocker x(Heap_lock);
1989
1990 // We have to initialize the printer before committing the heap, as
1991 // it will be used then.
1992 _hr_printer.set_active(G1PrintHeapRegions);
1993
1994 // While there are no constraints in the GC code that HeapWordSize
1995 // be any particular value, there are multiple other areas in the
1996 // system which believe this to be true (e.g. oop->object_size in some
1997 // cases incorrectly returns the size in wordSize units rather than
1998 // HeapWordSize).
1999 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2000
2001 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2002 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2003 size_t heap_alignment = collector_policy()->heap_alignment();
2004
2005 // Ensure that the sizes are properly aligned.
2006 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2007 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2008 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2009
2010 _refine_cte_cl = new RefineCardTableEntryClosure();
2011
2012 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2013
2014 // Reserve the maximum.
2015
2016 // When compressed oops are enabled, the preferred heap base
2017 // is calculated by subtracting the requested size from the
2018 // 32Gb boundary and using the result as the base address for
2019 // heap reservation. If the requested size is not aligned to
2020 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2021 // into the ReservedHeapSpace constructor) then the actual
2022 // base of the reserved heap may end up differing from the
2023 // address that was requested (i.e. the preferred heap base).
2024 // If this happens then we could end up using a non-optimal
2025 // compressed oops mode.
2026
2027 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2028 heap_alignment);
2029
2030 // It is important to do this in a way such that concurrent readers can't
2031 // temporarily think something is in the heap. (I've actually seen this
2032 // happen in asserts: DLD.)
2033 _reserved.set_word_size(0);
2034 _reserved.set_start((HeapWord*)heap_rs.base());
2035 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2036
2037 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2038
2039 // Create the gen rem set (and barrier set) for the entire reserved region.
2040 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2041 set_barrier_set(rem_set()->bs());
2042 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2043 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2044 return JNI_ENOMEM;
2045 }
2046
2047 // Also create a G1 rem set.
2048 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2049
2050 // Carve out the G1 part of the heap.
2051
2052 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2053 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2054 g1_rs.size()/HeapWordSize);
2055
2056 _g1_storage.initialize(g1_rs, 0);
2057 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2058 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2059 (HeapWord*) _g1_reserved.end());
2060 assert(_hrs.max_length() == _expansion_regions,
2061 err_msg("max length: %u expansion regions: %u",
2062 _hrs.max_length(), _expansion_regions));
2063
2064 // Do later initialization work for concurrent refinement.
2065 _cg1r->init();
2066
2067 // 6843694 - ensure that the maximum region index can fit
2068 // in the remembered set structures.
2069 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2070 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2071
2072 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2073 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2074 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2075 "too many cards per region");
2076
2077 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2078
2079 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2080 heap_word_size(init_byte_size));
2081
2082 _g1h = this;
2083
2084 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2085
2086 // Create the ConcurrentMark data structure and thread.
2087 // (Must do this late, so that "max_regions" is defined.)
2088 _cm = new ConcurrentMark(this, heap_rs);
2089 if (_cm == NULL || !_cm->completed_initialization()) {
2090 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2091 return JNI_ENOMEM;
2092 }
2093 _cmThread = _cm->cmThread();
2094
2095 // Initialize the from_card cache structure of HeapRegionRemSet.
2096 HeapRegionRemSet::init_heap(max_regions());
2097
2098 // Now expand into the initial heap size.
2099 if (!expand(init_byte_size)) {
2100 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2101 return JNI_ENOMEM;
2102 }
2103
2104 // Perform any initialization actions delegated to the policy.
2105 g1_policy()->init();
2106
2107 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2108 SATB_Q_FL_lock,
2109 G1SATBProcessCompletedThreshold,
2110 Shared_SATB_Q_lock);
2111
2112 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2113 DirtyCardQ_CBL_mon,
2114 DirtyCardQ_FL_lock,
2115 concurrent_g1_refine()->yellow_zone(),
2116 concurrent_g1_refine()->red_zone(),
2117 Shared_DirtyCardQ_lock);
2118
2119 if (G1DeferredRSUpdate) {
2120 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2121 DirtyCardQ_CBL_mon,
2122 DirtyCardQ_FL_lock,
2123 -1, // never trigger processing
2124 -1, // no limit on length
2125 Shared_DirtyCardQ_lock,
2126 &JavaThread::dirty_card_queue_set());
2127 }
2128
2129 // Initialize the card queue set used to hold cards containing
2130 // references into the collection set.
2131 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2132 DirtyCardQ_CBL_mon,
2133 DirtyCardQ_FL_lock,
2134 -1, // never trigger processing
2135 -1, // no limit on length
2136 Shared_DirtyCardQ_lock,
2137 &JavaThread::dirty_card_queue_set());
2138
2139 // In case we're keeping closure specialization stats, initialize those
2140 // counts and that mechanism.
2141 SpecializationStats::clear();
2142
2143 // Here we allocate the dummy full region that is required by the
2144 // G1AllocRegion class. If we don't pass an address in the reserved
2145 // space here, lots of asserts fire.
2146
2147 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2148 _g1_reserved.start());
2149 // We'll re-use the same region whether the alloc region will
2150 // require BOT updates or not and, if it doesn't, then a non-young
2151 // region will complain that it cannot support allocations without
2152 // BOT updates. So we'll tag the dummy region as young to avoid that.
2153 dummy_region->set_young();
2154 // Make sure it's full.
2155 dummy_region->set_top(dummy_region->end());
2156 G1AllocRegion::setup(this, dummy_region);
2157
2158 init_mutator_alloc_region();
2159
2160 // Do create of the monitoring and management support so that
2161 // values in the heap have been properly initialized.
2162 _g1mm = new G1MonitoringSupport(this);
2163
2164 G1StringDedup::initialize();
2165
2166 return JNI_OK;
2167 }
2168
2169 void G1CollectedHeap::stop() {
2170 // Stop all concurrent threads. We do this to make sure these threads
2171 // do not continue to execute and access resources (e.g. gclog_or_tty)
2172 // that are destroyed during shutdown.
2173 _cg1r->stop();
2174 _cmThread->stop();
2175 if (G1StringDedup::is_enabled()) {
2176 G1StringDedup::stop();
2177 }
2178 }
2179
2180 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2181 return HeapRegion::max_region_size();
2182 }
2183
2184 void G1CollectedHeap::ref_processing_init() {
2185 // Reference processing in G1 currently works as follows:
2186 //
2187 // * There are two reference processor instances. One is
2188 // used to record and process discovered references
2189 // during concurrent marking; the other is used to
2190 // record and process references during STW pauses
2191 // (both full and incremental).
2192 // * Both ref processors need to 'span' the entire heap as
2193 // the regions in the collection set may be dotted around.
2194 //
2195 // * For the concurrent marking ref processor:
2196 // * Reference discovery is enabled at initial marking.
2197 // * Reference discovery is disabled and the discovered
2198 // references processed etc during remarking.
2199 // * Reference discovery is MT (see below).
2200 // * Reference discovery requires a barrier (see below).
2201 // * Reference processing may or may not be MT
2202 // (depending on the value of ParallelRefProcEnabled
2203 // and ParallelGCThreads).
2204 // * A full GC disables reference discovery by the CM
2205 // ref processor and abandons any entries on it's
2206 // discovered lists.
2207 //
2208 // * For the STW processor:
2209 // * Non MT discovery is enabled at the start of a full GC.
2210 // * Processing and enqueueing during a full GC is non-MT.
2211 // * During a full GC, references are processed after marking.
2212 //
2213 // * Discovery (may or may not be MT) is enabled at the start
2214 // of an incremental evacuation pause.
2215 // * References are processed near the end of a STW evacuation pause.
2216 // * For both types of GC:
2217 // * Discovery is atomic - i.e. not concurrent.
2218 // * Reference discovery will not need a barrier.
2219
2220 SharedHeap::ref_processing_init();
2221 MemRegion mr = reserved_region();
2222
2223 // Concurrent Mark ref processor
2224 _ref_processor_cm =
2225 new ReferenceProcessor(mr, // span
2226 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2227 // mt processing
2228 (int) ParallelGCThreads,
2229 // degree of mt processing
2230 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2231 // mt discovery
2232 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2233 // degree of mt discovery
2234 false,
2235 // Reference discovery is not atomic
2236 &_is_alive_closure_cm);
2237 // is alive closure
2238 // (for efficiency/performance)
2239
2240 // STW ref processor
2241 _ref_processor_stw =
2242 new ReferenceProcessor(mr, // span
2243 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2244 // mt processing
2245 MAX2((int)ParallelGCThreads, 1),
2246 // degree of mt processing
2247 (ParallelGCThreads > 1),
2248 // mt discovery
2249 MAX2((int)ParallelGCThreads, 1),
2250 // degree of mt discovery
2251 true,
2252 // Reference discovery is atomic
2253 &_is_alive_closure_stw);
2254 // is alive closure
2255 // (for efficiency/performance)
2256 }
2257
2258 size_t G1CollectedHeap::capacity() const {
2259 return _g1_committed.byte_size();
2260 }
2261
2262 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2263 assert(!hr->continuesHumongous(), "pre-condition");
2264 hr->reset_gc_time_stamp();
2265 if (hr->startsHumongous()) {
2266 uint first_index = hr->hrs_index() + 1;
2267 uint last_index = hr->last_hc_index();
2268 for (uint i = first_index; i < last_index; i += 1) {
2269 HeapRegion* chr = region_at(i);
2270 assert(chr->continuesHumongous(), "sanity");
2271 chr->reset_gc_time_stamp();
2272 }
2273 }
2274 }
2275
2276 #ifndef PRODUCT
2277 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2278 private:
2279 unsigned _gc_time_stamp;
2280 bool _failures;
2281
2282 public:
2283 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2284 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2285
2286 virtual bool doHeapRegion(HeapRegion* hr) {
2287 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2288 if (_gc_time_stamp != region_gc_time_stamp) {
2289 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2290 "expected %d", HR_FORMAT_PARAMS(hr),
2291 region_gc_time_stamp, _gc_time_stamp);
2292 _failures = true;
2293 }
2294 return false;
2295 }
2296
2297 bool failures() { return _failures; }
2298 };
2299
2300 void G1CollectedHeap::check_gc_time_stamps() {
2301 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2302 heap_region_iterate(&cl);
2303 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2304 }
2305 #endif // PRODUCT
2306
2307 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2308 DirtyCardQueue* into_cset_dcq,
2309 bool concurrent,
2310 uint worker_i) {
2311 // Clean cards in the hot card cache
2312 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2313 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2314
2315 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2316 int n_completed_buffers = 0;
2317 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2318 n_completed_buffers++;
2319 }
2320 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2321 dcqs.clear_n_completed_buffers();
2322 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2323 }
2324
2325
2326 // Computes the sum of the storage used by the various regions.
2327
2328 size_t G1CollectedHeap::used() const {
2329 assert(Heap_lock->owner() != NULL,
2330 "Should be owned on this thread's behalf.");
2331 size_t result = _summary_bytes_used;
2332 // Read only once in case it is set to NULL concurrently
2333 HeapRegion* hr = _mutator_alloc_region.get();
2334 if (hr != NULL)
2335 result += hr->used();
2336 return result;
2337 }
2338
2339 size_t G1CollectedHeap::used_unlocked() const {
2340 size_t result = _summary_bytes_used;
2341 return result;
2342 }
2343
2344 class SumUsedClosure: public HeapRegionClosure {
2345 size_t _used;
2346 public:
2347 SumUsedClosure() : _used(0) {}
2348 bool doHeapRegion(HeapRegion* r) {
2349 if (!r->continuesHumongous()) {
2350 _used += r->used();
2351 }
2352 return false;
2353 }
2354 size_t result() { return _used; }
2355 };
2356
2357 size_t G1CollectedHeap::recalculate_used() const {
2358 double recalculate_used_start = os::elapsedTime();
2359
2360 SumUsedClosure blk;
2361 heap_region_iterate(&blk);
2362
2363 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2364 return blk.result();
2365 }
2366
2367 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2368 switch (cause) {
2369 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2370 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2371 case GCCause::_g1_humongous_allocation: return true;
2372 default: return false;
2373 }
2374 }
2375
2376 #ifndef PRODUCT
2377 void G1CollectedHeap::allocate_dummy_regions() {
2378 // Let's fill up most of the region
2379 size_t word_size = HeapRegion::GrainWords - 1024;
2380 // And as a result the region we'll allocate will be humongous.
2381 guarantee(isHumongous(word_size), "sanity");
2382
2383 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2384 // Let's use the existing mechanism for the allocation
2385 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2386 if (dummy_obj != NULL) {
2387 MemRegion mr(dummy_obj, word_size);
2388 CollectedHeap::fill_with_object(mr);
2389 } else {
2390 // If we can't allocate once, we probably cannot allocate
2391 // again. Let's get out of the loop.
2392 break;
2393 }
2394 }
2395 }
2396 #endif // !PRODUCT
2397
2398 void G1CollectedHeap::increment_old_marking_cycles_started() {
2399 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2400 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2401 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2402 _old_marking_cycles_started, _old_marking_cycles_completed));
2403
2404 _old_marking_cycles_started++;
2405 }
2406
2407 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2408 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2409
2410 // We assume that if concurrent == true, then the caller is a
2411 // concurrent thread that was joined the Suspendible Thread
2412 // Set. If there's ever a cheap way to check this, we should add an
2413 // assert here.
2414
2415 // Given that this method is called at the end of a Full GC or of a
2416 // concurrent cycle, and those can be nested (i.e., a Full GC can
2417 // interrupt a concurrent cycle), the number of full collections
2418 // completed should be either one (in the case where there was no
2419 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2420 // behind the number of full collections started.
2421
2422 // This is the case for the inner caller, i.e. a Full GC.
2423 assert(concurrent ||
2424 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2425 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2426 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2427 "is inconsistent with _old_marking_cycles_completed = %u",
2428 _old_marking_cycles_started, _old_marking_cycles_completed));
2429
2430 // This is the case for the outer caller, i.e. the concurrent cycle.
2431 assert(!concurrent ||
2432 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2433 err_msg("for outer caller (concurrent cycle): "
2434 "_old_marking_cycles_started = %u "
2435 "is inconsistent with _old_marking_cycles_completed = %u",
2436 _old_marking_cycles_started, _old_marking_cycles_completed));
2437
2438 _old_marking_cycles_completed += 1;
2439
2440 // We need to clear the "in_progress" flag in the CM thread before
2441 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2442 // is set) so that if a waiter requests another System.gc() it doesn't
2443 // incorrectly see that a marking cycle is still in progress.
2444 if (concurrent) {
2445 _cmThread->clear_in_progress();
2446 }
2447
2448 // This notify_all() will ensure that a thread that called
2449 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2450 // and it's waiting for a full GC to finish will be woken up. It is
2451 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2452 FullGCCount_lock->notify_all();
2453 }
2454
2455 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2456 _concurrent_cycle_started = true;
2457 _gc_timer_cm->register_gc_start(start_time);
2458
2459 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2460 trace_heap_before_gc(_gc_tracer_cm);
2461 }
2462
2463 void G1CollectedHeap::register_concurrent_cycle_end() {
2464 if (_concurrent_cycle_started) {
2465 if (_cm->has_aborted()) {
2466 _gc_tracer_cm->report_concurrent_mode_failure();
2467 }
2468
2469 _gc_timer_cm->register_gc_end();
2470 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2471
2472 _concurrent_cycle_started = false;
2473 }
2474 }
2475
2476 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2477 if (_concurrent_cycle_started) {
2478 trace_heap_after_gc(_gc_tracer_cm);
2479 }
2480 }
2481
2482 G1YCType G1CollectedHeap::yc_type() {
2483 bool is_young = g1_policy()->gcs_are_young();
2484 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2485 bool is_during_mark = mark_in_progress();
2486
2487 if (is_initial_mark) {
2488 return InitialMark;
2489 } else if (is_during_mark) {
2490 return DuringMark;
2491 } else if (is_young) {
2492 return Normal;
2493 } else {
2494 return Mixed;
2495 }
2496 }
2497
2498 void G1CollectedHeap::collect(GCCause::Cause cause) {
2499 assert_heap_not_locked();
2500
2501 unsigned int gc_count_before;
2502 unsigned int old_marking_count_before;
2503 bool retry_gc;
2504
2505 do {
2506 retry_gc = false;
2507
2508 {
2509 MutexLocker ml(Heap_lock);
2510
2511 // Read the GC count while holding the Heap_lock
2512 gc_count_before = total_collections();
2513 old_marking_count_before = _old_marking_cycles_started;
2514 }
2515
2516 if (should_do_concurrent_full_gc(cause)) {
2517 // Schedule an initial-mark evacuation pause that will start a
2518 // concurrent cycle. We're setting word_size to 0 which means that
2519 // we are not requesting a post-GC allocation.
2520 VM_G1IncCollectionPause op(gc_count_before,
2521 0, /* word_size */
2522 true, /* should_initiate_conc_mark */
2523 g1_policy()->max_pause_time_ms(),
2524 cause);
2525
2526 VMThread::execute(&op);
2527 if (!op.pause_succeeded()) {
2528 if (old_marking_count_before == _old_marking_cycles_started) {
2529 retry_gc = op.should_retry_gc();
2530 } else {
2531 // A Full GC happened while we were trying to schedule the
2532 // initial-mark GC. No point in starting a new cycle given
2533 // that the whole heap was collected anyway.
2534 }
2535
2536 if (retry_gc) {
2537 if (GC_locker::is_active_and_needs_gc()) {
2538 GC_locker::stall_until_clear();
2539 }
2540 }
2541 }
2542 } else {
2543 if (cause == GCCause::_gc_locker
2544 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2545
2546 // Schedule a standard evacuation pause. We're setting word_size
2547 // to 0 which means that we are not requesting a post-GC allocation.
2548 VM_G1IncCollectionPause op(gc_count_before,
2549 0, /* word_size */
2550 false, /* should_initiate_conc_mark */
2551 g1_policy()->max_pause_time_ms(),
2552 cause);
2553 VMThread::execute(&op);
2554 } else {
2555 // Schedule a Full GC.
2556 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2557 VMThread::execute(&op);
2558 }
2559 }
2560 } while (retry_gc);
2561 }
2562
2563 bool G1CollectedHeap::is_in(const void* p) const {
2564 if (_g1_committed.contains(p)) {
2565 // Given that we know that p is in the committed space,
2566 // heap_region_containing_raw() should successfully
2567 // return the containing region.
2568 HeapRegion* hr = heap_region_containing_raw(p);
2569 return hr->is_in(p);
2570 } else {
2571 return false;
2572 }
2573 }
2574
2575 // Iteration functions.
2576
2577 // Iterates an OopClosure over all ref-containing fields of objects
2578 // within a HeapRegion.
2579
2580 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2581 MemRegion _mr;
2582 ExtendedOopClosure* _cl;
2583 public:
2584 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2585 : _mr(mr), _cl(cl) {}
2586 bool doHeapRegion(HeapRegion* r) {
2587 if (!r->continuesHumongous()) {
2588 r->oop_iterate(_cl);
2589 }
2590 return false;
2591 }
2592 };
2593
2594 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2595 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2596 heap_region_iterate(&blk);
2597 }
2598
2599 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2600 IterateOopClosureRegionClosure blk(mr, cl);
2601 heap_region_iterate(&blk);
2602 }
2603
2604 // Iterates an ObjectClosure over all objects within a HeapRegion.
2605
2606 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2607 ObjectClosure* _cl;
2608 public:
2609 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2610 bool doHeapRegion(HeapRegion* r) {
2611 if (! r->continuesHumongous()) {
2612 r->object_iterate(_cl);
2613 }
2614 return false;
2615 }
2616 };
2617
2618 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2619 IterateObjectClosureRegionClosure blk(cl);
2620 heap_region_iterate(&blk);
2621 }
2622
2623 // Calls a SpaceClosure on a HeapRegion.
2624
2625 class SpaceClosureRegionClosure: public HeapRegionClosure {
2626 SpaceClosure* _cl;
2627 public:
2628 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2629 bool doHeapRegion(HeapRegion* r) {
2630 _cl->do_space(r);
2631 return false;
2632 }
2633 };
2634
2635 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2636 SpaceClosureRegionClosure blk(cl);
2637 heap_region_iterate(&blk);
2638 }
2639
2640 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2641 _hrs.iterate(cl);
2642 }
2643
2644 void
2645 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2646 uint worker_id,
2647 uint no_of_par_workers,
2648 jint claim_value) {
2649 const uint regions = n_regions();
2650 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2651 no_of_par_workers :
2652 1);
2653 assert(UseDynamicNumberOfGCThreads ||
2654 no_of_par_workers == workers()->total_workers(),
2655 "Non dynamic should use fixed number of workers");
2656 // try to spread out the starting points of the workers
2657 const HeapRegion* start_hr =
2658 start_region_for_worker(worker_id, no_of_par_workers);
2659 const uint start_index = start_hr->hrs_index();
2660
2661 // each worker will actually look at all regions
2662 for (uint count = 0; count < regions; ++count) {
2663 const uint index = (start_index + count) % regions;
2664 assert(0 <= index && index < regions, "sanity");
2665 HeapRegion* r = region_at(index);
2666 // we'll ignore "continues humongous" regions (we'll process them
2667 // when we come across their corresponding "start humongous"
2668 // region) and regions already claimed
2669 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2670 continue;
2671 }
2672 // OK, try to claim it
2673 if (r->claimHeapRegion(claim_value)) {
2674 // success!
2675 assert(!r->continuesHumongous(), "sanity");
2676 if (r->startsHumongous()) {
2677 // If the region is "starts humongous" we'll iterate over its
2678 // "continues humongous" first; in fact we'll do them
2679 // first. The order is important. In on case, calling the
2680 // closure on the "starts humongous" region might de-allocate
2681 // and clear all its "continues humongous" regions and, as a
2682 // result, we might end up processing them twice. So, we'll do
2683 // them first (notice: most closures will ignore them anyway) and
2684 // then we'll do the "starts humongous" region.
2685 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2686 HeapRegion* chr = region_at(ch_index);
2687
2688 // if the region has already been claimed or it's not
2689 // "continues humongous" we're done
2690 if (chr->claim_value() == claim_value ||
2691 !chr->continuesHumongous()) {
2692 break;
2693 }
2694
2695 // No one should have claimed it directly. We can given
2696 // that we claimed its "starts humongous" region.
2697 assert(chr->claim_value() != claim_value, "sanity");
2698 assert(chr->humongous_start_region() == r, "sanity");
2699
2700 if (chr->claimHeapRegion(claim_value)) {
2701 // we should always be able to claim it; no one else should
2702 // be trying to claim this region
2703
2704 bool res2 = cl->doHeapRegion(chr);
2705 assert(!res2, "Should not abort");
2706
2707 // Right now, this holds (i.e., no closure that actually
2708 // does something with "continues humongous" regions
2709 // clears them). We might have to weaken it in the future,
2710 // but let's leave these two asserts here for extra safety.
2711 assert(chr->continuesHumongous(), "should still be the case");
2712 assert(chr->humongous_start_region() == r, "sanity");
2713 } else {
2714 guarantee(false, "we should not reach here");
2715 }
2716 }
2717 }
2718
2719 assert(!r->continuesHumongous(), "sanity");
2720 bool res = cl->doHeapRegion(r);
2721 assert(!res, "Should not abort");
2722 }
2723 }
2724 }
2725
2726 class ResetClaimValuesClosure: public HeapRegionClosure {
2727 public:
2728 bool doHeapRegion(HeapRegion* r) {
2729 r->set_claim_value(HeapRegion::InitialClaimValue);
2730 return false;
2731 }
2732 };
2733
2734 void G1CollectedHeap::reset_heap_region_claim_values() {
2735 ResetClaimValuesClosure blk;
2736 heap_region_iterate(&blk);
2737 }
2738
2739 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2740 ResetClaimValuesClosure blk;
2741 collection_set_iterate(&blk);
2742 }
2743
2744 #ifdef ASSERT
2745 // This checks whether all regions in the heap have the correct claim
2746 // value. I also piggy-backed on this a check to ensure that the
2747 // humongous_start_region() information on "continues humongous"
2748 // regions is correct.
2749
2750 class CheckClaimValuesClosure : public HeapRegionClosure {
2751 private:
2752 jint _claim_value;
2753 uint _failures;
2754 HeapRegion* _sh_region;
2755
2756 public:
2757 CheckClaimValuesClosure(jint claim_value) :
2758 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2759 bool doHeapRegion(HeapRegion* r) {
2760 if (r->claim_value() != _claim_value) {
2761 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2762 "claim value = %d, should be %d",
2763 HR_FORMAT_PARAMS(r),
2764 r->claim_value(), _claim_value);
2765 ++_failures;
2766 }
2767 if (!r->isHumongous()) {
2768 _sh_region = NULL;
2769 } else if (r->startsHumongous()) {
2770 _sh_region = r;
2771 } else if (r->continuesHumongous()) {
2772 if (r->humongous_start_region() != _sh_region) {
2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2774 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2775 HR_FORMAT_PARAMS(r),
2776 r->humongous_start_region(),
2777 _sh_region);
2778 ++_failures;
2779 }
2780 }
2781 return false;
2782 }
2783 uint failures() { return _failures; }
2784 };
2785
2786 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2787 CheckClaimValuesClosure cl(claim_value);
2788 heap_region_iterate(&cl);
2789 return cl.failures() == 0;
2790 }
2791
2792 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2793 private:
2794 jint _claim_value;
2795 uint _failures;
2796
2797 public:
2798 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2799 _claim_value(claim_value), _failures(0) { }
2800
2801 uint failures() { return _failures; }
2802
2803 bool doHeapRegion(HeapRegion* hr) {
2804 assert(hr->in_collection_set(), "how?");
2805 assert(!hr->isHumongous(), "H-region in CSet");
2806 if (hr->claim_value() != _claim_value) {
2807 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2808 "claim value = %d, should be %d",
2809 HR_FORMAT_PARAMS(hr),
2810 hr->claim_value(), _claim_value);
2811 _failures += 1;
2812 }
2813 return false;
2814 }
2815 };
2816
2817 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2818 CheckClaimValuesInCSetHRClosure cl(claim_value);
2819 collection_set_iterate(&cl);
2820 return cl.failures() == 0;
2821 }
2822 #endif // ASSERT
2823
2824 // Clear the cached CSet starting regions and (more importantly)
2825 // the time stamps. Called when we reset the GC time stamp.
2826 void G1CollectedHeap::clear_cset_start_regions() {
2827 assert(_worker_cset_start_region != NULL, "sanity");
2828 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2829
2830 int n_queues = MAX2((int)ParallelGCThreads, 1);
2831 for (int i = 0; i < n_queues; i++) {
2832 _worker_cset_start_region[i] = NULL;
2833 _worker_cset_start_region_time_stamp[i] = 0;
2834 }
2835 }
2836
2837 // Given the id of a worker, obtain or calculate a suitable
2838 // starting region for iterating over the current collection set.
2839 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2840 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2841
2842 HeapRegion* result = NULL;
2843 unsigned gc_time_stamp = get_gc_time_stamp();
2844
2845 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2846 // Cached starting region for current worker was set
2847 // during the current pause - so it's valid.
2848 // Note: the cached starting heap region may be NULL
2849 // (when the collection set is empty).
2850 result = _worker_cset_start_region[worker_i];
2851 assert(result == NULL || result->in_collection_set(), "sanity");
2852 return result;
2853 }
2854
2855 // The cached entry was not valid so let's calculate
2856 // a suitable starting heap region for this worker.
2857
2858 // We want the parallel threads to start their collection
2859 // set iteration at different collection set regions to
2860 // avoid contention.
2861 // If we have:
2862 // n collection set regions
2863 // p threads
2864 // Then thread t will start at region floor ((t * n) / p)
2865
2866 result = g1_policy()->collection_set();
2867 if (G1CollectedHeap::use_parallel_gc_threads()) {
2868 uint cs_size = g1_policy()->cset_region_length();
2869 uint active_workers = workers()->active_workers();
2870 assert(UseDynamicNumberOfGCThreads ||
2871 active_workers == workers()->total_workers(),
2872 "Unless dynamic should use total workers");
2873
2874 uint end_ind = (cs_size * worker_i) / active_workers;
2875 uint start_ind = 0;
2876
2877 if (worker_i > 0 &&
2878 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2879 // Previous workers starting region is valid
2880 // so let's iterate from there
2881 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2882 result = _worker_cset_start_region[worker_i - 1];
2883 }
2884
2885 for (uint i = start_ind; i < end_ind; i++) {
2886 result = result->next_in_collection_set();
2887 }
2888 }
2889
2890 // Note: the calculated starting heap region may be NULL
2891 // (when the collection set is empty).
2892 assert(result == NULL || result->in_collection_set(), "sanity");
2893 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2894 "should be updated only once per pause");
2895 _worker_cset_start_region[worker_i] = result;
2896 OrderAccess::storestore();
2897 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2898 return result;
2899 }
2900
2901 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2902 uint no_of_par_workers) {
2903 uint worker_num =
2904 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2905 assert(UseDynamicNumberOfGCThreads ||
2906 no_of_par_workers == workers()->total_workers(),
2907 "Non dynamic should use fixed number of workers");
2908 const uint start_index = n_regions() * worker_i / worker_num;
2909 return region_at(start_index);
2910 }
2911
2912 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2913 HeapRegion* r = g1_policy()->collection_set();
2914 while (r != NULL) {
2915 HeapRegion* next = r->next_in_collection_set();
2916 if (cl->doHeapRegion(r)) {
2917 cl->incomplete();
2918 return;
2919 }
2920 r = next;
2921 }
2922 }
2923
2924 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2925 HeapRegionClosure *cl) {
2926 if (r == NULL) {
2927 // The CSet is empty so there's nothing to do.
2928 return;
2929 }
2930
2931 assert(r->in_collection_set(),
2932 "Start region must be a member of the collection set.");
2933 HeapRegion* cur = r;
2934 while (cur != NULL) {
2935 HeapRegion* next = cur->next_in_collection_set();
2936 if (cl->doHeapRegion(cur) && false) {
2937 cl->incomplete();
2938 return;
2939 }
2940 cur = next;
2941 }
2942 cur = g1_policy()->collection_set();
2943 while (cur != r) {
2944 HeapRegion* next = cur->next_in_collection_set();
2945 if (cl->doHeapRegion(cur) && false) {
2946 cl->incomplete();
2947 return;
2948 }
2949 cur = next;
2950 }
2951 }
2952
2953 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2954 // We're not using an iterator given that it will wrap around when
2955 // it reaches the last region and this is not what we want here.
2956 uint index = from->hrs_index() + 1;
2957 while (index < n_regions()) {
2958 HeapRegion* hr = region_at(index);
2959 if (!hr->isHumongous()) {
2960 return hr;
2961 }
2962 index += 1;
2963 }
2964 return NULL;
2965 }
2966
2967 Space* G1CollectedHeap::space_containing(const void* addr) const {
2968 return heap_region_containing(addr);
2969 }
2970
2971 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2972 Space* sp = space_containing(addr);
2973 return sp->block_start(addr);
2974 }
2975
2976 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2977 Space* sp = space_containing(addr);
2978 return sp->block_size(addr);
2979 }
2980
2981 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2982 Space* sp = space_containing(addr);
2983 return sp->block_is_obj(addr);
2984 }
2985
2986 bool G1CollectedHeap::supports_tlab_allocation() const {
2987 return true;
2988 }
2989
2990 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2991 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2992 }
2993
2994 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2995 return young_list()->eden_used_bytes();
2996 }
2997
2998 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2999 // must be smaller than the humongous object limit.
3000 size_t G1CollectedHeap::max_tlab_size() const {
3001 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3002 }
3003
3004 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3005 // Return the remaining space in the cur alloc region, but not less than
3006 // the min TLAB size.
3007
3008 // Also, this value can be at most the humongous object threshold,
3009 // since we can't allow tlabs to grow big enough to accommodate
3010 // humongous objects.
3011
3012 HeapRegion* hr = _mutator_alloc_region.get();
3013 size_t max_tlab = max_tlab_size() * wordSize;
3014 if (hr == NULL) {
3015 return max_tlab;
3016 } else {
3017 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3018 }
3019 }
3020
3021 size_t G1CollectedHeap::max_capacity() const {
3022 return _g1_reserved.byte_size();
3023 }
3024
3025 jlong G1CollectedHeap::millis_since_last_gc() {
3026 // assert(false, "NYI");
3027 return 0;
3028 }
3029
3030 void G1CollectedHeap::prepare_for_verify() {
3031 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3032 ensure_parsability(false);
3033 }
3034 g1_rem_set()->prepare_for_verify();
3035 }
3036
3037 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3038 VerifyOption vo) {
3039 switch (vo) {
3040 case VerifyOption_G1UsePrevMarking:
3041 return hr->obj_allocated_since_prev_marking(obj);
3042 case VerifyOption_G1UseNextMarking:
3043 return hr->obj_allocated_since_next_marking(obj);
3044 case VerifyOption_G1UseMarkWord:
3045 return false;
3046 default:
3047 ShouldNotReachHere();
3048 }
3049 return false; // keep some compilers happy
3050 }
3051
3052 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3053 switch (vo) {
3054 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3055 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3056 case VerifyOption_G1UseMarkWord: return NULL;
3057 default: ShouldNotReachHere();
3058 }
3059 return NULL; // keep some compilers happy
3060 }
3061
3062 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3063 switch (vo) {
3064 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3065 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3066 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3067 default: ShouldNotReachHere();
3068 }
3069 return false; // keep some compilers happy
3070 }
3071
3072 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3073 switch (vo) {
3074 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3075 case VerifyOption_G1UseNextMarking: return "NTAMS";
3076 case VerifyOption_G1UseMarkWord: return "NONE";
3077 default: ShouldNotReachHere();
3078 }
3079 return NULL; // keep some compilers happy
3080 }
3081
3082 class VerifyRootsClosure: public OopClosure {
3083 private:
3084 G1CollectedHeap* _g1h;
3085 VerifyOption _vo;
3086 bool _failures;
3087 public:
3088 // _vo == UsePrevMarking -> use "prev" marking information,
3089 // _vo == UseNextMarking -> use "next" marking information,
3090 // _vo == UseMarkWord -> use mark word from object header.
3091 VerifyRootsClosure(VerifyOption vo) :
3092 _g1h(G1CollectedHeap::heap()),
3093 _vo(vo),
3094 _failures(false) { }
3095
3096 bool failures() { return _failures; }
3097
3098 template <class T> void do_oop_nv(T* p) {
3099 T heap_oop = oopDesc::load_heap_oop(p);
3100 if (!oopDesc::is_null(heap_oop)) {
3101 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3102 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3103 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3104 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3105 if (_vo == VerifyOption_G1UseMarkWord) {
3106 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3107 }
3108 obj->print_on(gclog_or_tty);
3109 _failures = true;
3110 }
3111 }
3112 }
3113
3114 void do_oop(oop* p) { do_oop_nv(p); }
3115 void do_oop(narrowOop* p) { do_oop_nv(p); }
3116 };
3117
3118 class G1VerifyCodeRootOopClosure: public OopClosure {
3119 G1CollectedHeap* _g1h;
3120 OopClosure* _root_cl;
3121 nmethod* _nm;
3122 VerifyOption _vo;
3123 bool _failures;
3124
3125 template <class T> void do_oop_work(T* p) {
3126 // First verify that this root is live
3127 _root_cl->do_oop(p);
3128
3129 if (!G1VerifyHeapRegionCodeRoots) {
3130 // We're not verifying the code roots attached to heap region.
3131 return;
3132 }
3133
3134 // Don't check the code roots during marking verification in a full GC
3135 if (_vo == VerifyOption_G1UseMarkWord) {
3136 return;
3137 }
3138
3139 // Now verify that the current nmethod (which contains p) is
3140 // in the code root list of the heap region containing the
3141 // object referenced by p.
3142
3143 T heap_oop = oopDesc::load_heap_oop(p);
3144 if (!oopDesc::is_null(heap_oop)) {
3145 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3146
3147 // Now fetch the region containing the object
3148 HeapRegion* hr = _g1h->heap_region_containing(obj);
3149 HeapRegionRemSet* hrrs = hr->rem_set();
3150 // Verify that the strong code root list for this region
3151 // contains the nmethod
3152 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3153 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3154 "from nmethod "PTR_FORMAT" not in strong "
3155 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3156 p, _nm, hr->bottom(), hr->end());
3157 _failures = true;
3158 }
3159 }
3160 }
3161
3162 public:
3163 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3164 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3165
3166 void do_oop(oop* p) { do_oop_work(p); }
3167 void do_oop(narrowOop* p) { do_oop_work(p); }
3168
3169 void set_nmethod(nmethod* nm) { _nm = nm; }
3170 bool failures() { return _failures; }
3171 };
3172
3173 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3174 G1VerifyCodeRootOopClosure* _oop_cl;
3175
3176 public:
3177 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3178 _oop_cl(oop_cl) {}
3179
3180 void do_code_blob(CodeBlob* cb) {
3181 nmethod* nm = cb->as_nmethod_or_null();
3182 if (nm != NULL) {
3183 _oop_cl->set_nmethod(nm);
3184 nm->oops_do(_oop_cl);
3185 }
3186 }
3187 };
3188
3189 class YoungRefCounterClosure : public OopClosure {
3190 G1CollectedHeap* _g1h;
3191 int _count;
3192 public:
3193 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3194 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3195 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3196
3197 int count() { return _count; }
3198 void reset_count() { _count = 0; };
3199 };
3200
3201 class VerifyKlassClosure: public KlassClosure {
3202 YoungRefCounterClosure _young_ref_counter_closure;
3203 OopClosure *_oop_closure;
3204 public:
3205 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3206 void do_klass(Klass* k) {
3207 k->oops_do(_oop_closure);
3208
3209 _young_ref_counter_closure.reset_count();
3210 k->oops_do(&_young_ref_counter_closure);
3211 if (_young_ref_counter_closure.count() > 0) {
3212 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3213 }
3214 }
3215 };
3216
3217 class VerifyLivenessOopClosure: public OopClosure {
3218 G1CollectedHeap* _g1h;
3219 VerifyOption _vo;
3220 public:
3221 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3222 _g1h(g1h), _vo(vo)
3223 { }
3224 void do_oop(narrowOop *p) { do_oop_work(p); }
3225 void do_oop( oop *p) { do_oop_work(p); }
3226
3227 template <class T> void do_oop_work(T *p) {
3228 oop obj = oopDesc::load_decode_heap_oop(p);
3229 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3230 "Dead object referenced by a not dead object");
3231 }
3232 };
3233
3234 class VerifyObjsInRegionClosure: public ObjectClosure {
3235 private:
3236 G1CollectedHeap* _g1h;
3237 size_t _live_bytes;
3238 HeapRegion *_hr;
3239 VerifyOption _vo;
3240 public:
3241 // _vo == UsePrevMarking -> use "prev" marking information,
3242 // _vo == UseNextMarking -> use "next" marking information,
3243 // _vo == UseMarkWord -> use mark word from object header.
3244 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3245 : _live_bytes(0), _hr(hr), _vo(vo) {
3246 _g1h = G1CollectedHeap::heap();
3247 }
3248 void do_object(oop o) {
3249 VerifyLivenessOopClosure isLive(_g1h, _vo);
3250 assert(o != NULL, "Huh?");
3251 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3252 // If the object is alive according to the mark word,
3253 // then verify that the marking information agrees.
3254 // Note we can't verify the contra-positive of the
3255 // above: if the object is dead (according to the mark
3256 // word), it may not be marked, or may have been marked
3257 // but has since became dead, or may have been allocated
3258 // since the last marking.
3259 if (_vo == VerifyOption_G1UseMarkWord) {
3260 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3261 }
3262
3263 o->oop_iterate_no_header(&isLive);
3264 if (!_hr->obj_allocated_since_prev_marking(o)) {
3265 size_t obj_size = o->size(); // Make sure we don't overflow
3266 _live_bytes += (obj_size * HeapWordSize);
3267 }
3268 }
3269 }
3270 size_t live_bytes() { return _live_bytes; }
3271 };
3272
3273 class PrintObjsInRegionClosure : public ObjectClosure {
3274 HeapRegion *_hr;
3275 G1CollectedHeap *_g1;
3276 public:
3277 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3278 _g1 = G1CollectedHeap::heap();
3279 };
3280
3281 void do_object(oop o) {
3282 if (o != NULL) {
3283 HeapWord *start = (HeapWord *) o;
3284 size_t word_sz = o->size();
3285 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3286 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3287 (void*) o, word_sz,
3288 _g1->isMarkedPrev(o),
3289 _g1->isMarkedNext(o),
3290 _hr->obj_allocated_since_prev_marking(o));
3291 HeapWord *end = start + word_sz;
3292 HeapWord *cur;
3293 int *val;
3294 for (cur = start; cur < end; cur++) {
3295 val = (int *) cur;
3296 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3297 }
3298 }
3299 }
3300 };
3301
3302 class VerifyRegionClosure: public HeapRegionClosure {
3303 private:
3304 bool _par;
3305 VerifyOption _vo;
3306 bool _failures;
3307 public:
3308 // _vo == UsePrevMarking -> use "prev" marking information,
3309 // _vo == UseNextMarking -> use "next" marking information,
3310 // _vo == UseMarkWord -> use mark word from object header.
3311 VerifyRegionClosure(bool par, VerifyOption vo)
3312 : _par(par),
3313 _vo(vo),
3314 _failures(false) {}
3315
3316 bool failures() {
3317 return _failures;
3318 }
3319
3320 bool doHeapRegion(HeapRegion* r) {
3321 if (!r->continuesHumongous()) {
3322 bool failures = false;
3323 r->verify(_vo, &failures);
3324 if (failures) {
3325 _failures = true;
3326 } else {
3327 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3328 r->object_iterate(¬_dead_yet_cl);
3329 if (_vo != VerifyOption_G1UseNextMarking) {
3330 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3331 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3332 "max_live_bytes "SIZE_FORMAT" "
3333 "< calculated "SIZE_FORMAT,
3334 r->bottom(), r->end(),
3335 r->max_live_bytes(),
3336 not_dead_yet_cl.live_bytes());
3337 _failures = true;
3338 }
3339 } else {
3340 // When vo == UseNextMarking we cannot currently do a sanity
3341 // check on the live bytes as the calculation has not been
3342 // finalized yet.
3343 }
3344 }
3345 }
3346 return false; // stop the region iteration if we hit a failure
3347 }
3348 };
3349
3350 // This is the task used for parallel verification of the heap regions
3351
3352 class G1ParVerifyTask: public AbstractGangTask {
3353 private:
3354 G1CollectedHeap* _g1h;
3355 VerifyOption _vo;
3356 bool _failures;
3357
3358 public:
3359 // _vo == UsePrevMarking -> use "prev" marking information,
3360 // _vo == UseNextMarking -> use "next" marking information,
3361 // _vo == UseMarkWord -> use mark word from object header.
3362 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3363 AbstractGangTask("Parallel verify task"),
3364 _g1h(g1h),
3365 _vo(vo),
3366 _failures(false) { }
3367
3368 bool failures() {
3369 return _failures;
3370 }
3371
3372 void work(uint worker_id) {
3373 HandleMark hm;
3374 VerifyRegionClosure blk(true, _vo);
3375 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3376 _g1h->workers()->active_workers(),
3377 HeapRegion::ParVerifyClaimValue);
3378 if (blk.failures()) {
3379 _failures = true;
3380 }
3381 }
3382 };
3383
3384 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3385 if (SafepointSynchronize::is_at_safepoint()) {
3386 assert(Thread::current()->is_VM_thread(),
3387 "Expected to be executed serially by the VM thread at this point");
3388
3389 if (!silent) { gclog_or_tty->print("Roots "); }
3390 VerifyRootsClosure rootsCl(vo);
3391 VerifyKlassClosure klassCl(this, &rootsCl);
3392 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3393
3394 // We apply the relevant closures to all the oops in the
3395 // system dictionary, class loader data graph, the string table
3396 // and the nmethods in the code cache.
3397 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3398 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3399
3400 process_all_roots(true, // activate StrongRootsScope
3401 SO_AllCodeCache, // roots scanning options
3402 &rootsCl,
3403 &cldCl,
3404 &blobsCl);
3405
3406 bool failures = rootsCl.failures() || codeRootsCl.failures();
3407
3408 if (vo != VerifyOption_G1UseMarkWord) {
3409 // If we're verifying during a full GC then the region sets
3410 // will have been torn down at the start of the GC. Therefore
3411 // verifying the region sets will fail. So we only verify
3412 // the region sets when not in a full GC.
3413 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3414 verify_region_sets();
3415 }
3416
3417 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3418 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3419 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3420 "sanity check");
3421
3422 G1ParVerifyTask task(this, vo);
3423 assert(UseDynamicNumberOfGCThreads ||
3424 workers()->active_workers() == workers()->total_workers(),
3425 "If not dynamic should be using all the workers");
3426 int n_workers = workers()->active_workers();
3427 set_par_threads(n_workers);
3428 workers()->run_task(&task);
3429 set_par_threads(0);
3430 if (task.failures()) {
3431 failures = true;
3432 }
3433
3434 // Checks that the expected amount of parallel work was done.
3435 // The implication is that n_workers is > 0.
3436 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3437 "sanity check");
3438
3439 reset_heap_region_claim_values();
3440
3441 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3442 "sanity check");
3443 } else {
3444 VerifyRegionClosure blk(false, vo);
3445 heap_region_iterate(&blk);
3446 if (blk.failures()) {
3447 failures = true;
3448 }
3449 }
3450 if (!silent) gclog_or_tty->print("RemSet ");
3451 rem_set()->verify();
3452
3453 if (G1StringDedup::is_enabled()) {
3454 if (!silent) gclog_or_tty->print("StrDedup ");
3455 G1StringDedup::verify();
3456 }
3457
3458 if (failures) {
3459 gclog_or_tty->print_cr("Heap:");
3460 // It helps to have the per-region information in the output to
3461 // help us track down what went wrong. This is why we call
3462 // print_extended_on() instead of print_on().
3463 print_extended_on(gclog_or_tty);
3464 gclog_or_tty->cr();
3465 #ifndef PRODUCT
3466 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3467 concurrent_mark()->print_reachable("at-verification-failure",
3468 vo, false /* all */);
3469 }
3470 #endif
3471 gclog_or_tty->flush();
3472 }
3473 guarantee(!failures, "there should not have been any failures");
3474 } else {
3475 if (!silent) {
3476 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3477 if (G1StringDedup::is_enabled()) {
3478 gclog_or_tty->print(", StrDedup");
3479 }
3480 gclog_or_tty->print(") ");
3481 }
3482 }
3483 }
3484
3485 void G1CollectedHeap::verify(bool silent) {
3486 verify(silent, VerifyOption_G1UsePrevMarking);
3487 }
3488
3489 double G1CollectedHeap::verify(bool guard, const char* msg) {
3490 double verify_time_ms = 0.0;
3491
3492 if (guard && total_collections() >= VerifyGCStartAt) {
3493 double verify_start = os::elapsedTime();
3494 HandleMark hm; // Discard invalid handles created during verification
3495 prepare_for_verify();
3496 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3497 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3498 }
3499
3500 return verify_time_ms;
3501 }
3502
3503 void G1CollectedHeap::verify_before_gc() {
3504 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3505 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3506 }
3507
3508 void G1CollectedHeap::verify_after_gc() {
3509 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3510 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3511 }
3512
3513 class PrintRegionClosure: public HeapRegionClosure {
3514 outputStream* _st;
3515 public:
3516 PrintRegionClosure(outputStream* st) : _st(st) {}
3517 bool doHeapRegion(HeapRegion* r) {
3518 r->print_on(_st);
3519 return false;
3520 }
3521 };
3522
3523 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3524 const HeapRegion* hr,
3525 const VerifyOption vo) const {
3526 switch (vo) {
3527 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3528 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3529 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3530 default: ShouldNotReachHere();
3531 }
3532 return false; // keep some compilers happy
3533 }
3534
3535 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3536 const VerifyOption vo) const {
3537 switch (vo) {
3538 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3539 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3540 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3541 default: ShouldNotReachHere();
3542 }
3543 return false; // keep some compilers happy
3544 }
3545
3546 void G1CollectedHeap::print_on(outputStream* st) const {
3547 st->print(" %-20s", "garbage-first heap");
3548 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3549 capacity()/K, used_unlocked()/K);
3550 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3551 _g1_storage.low_boundary(),
3552 _g1_storage.high(),
3553 _g1_storage.high_boundary());
3554 st->cr();
3555 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3556 uint young_regions = _young_list->length();
3557 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3558 (size_t) young_regions * HeapRegion::GrainBytes / K);
3559 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3560 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3561 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3562 st->cr();
3563 MetaspaceAux::print_on(st);
3564 }
3565
3566 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3567 print_on(st);
3568
3569 // Print the per-region information.
3570 st->cr();
3571 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3572 "HS=humongous(starts), HC=humongous(continues), "
3573 "CS=collection set, F=free, TS=gc time stamp, "
3574 "PTAMS=previous top-at-mark-start, "
3575 "NTAMS=next top-at-mark-start)");
3576 PrintRegionClosure blk(st);
3577 heap_region_iterate(&blk);
3578 }
3579
3580 void G1CollectedHeap::print_on_error(outputStream* st) const {
3581 this->CollectedHeap::print_on_error(st);
3582
3583 if (_cm != NULL) {
3584 st->cr();
3585 _cm->print_on_error(st);
3586 }
3587 }
3588
3589 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3590 if (G1CollectedHeap::use_parallel_gc_threads()) {
3591 workers()->print_worker_threads_on(st);
3592 }
3593 _cmThread->print_on(st);
3594 st->cr();
3595 _cm->print_worker_threads_on(st);
3596 _cg1r->print_worker_threads_on(st);
3597 if (G1StringDedup::is_enabled()) {
3598 G1StringDedup::print_worker_threads_on(st);
3599 }
3600 }
3601
3602 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3603 if (G1CollectedHeap::use_parallel_gc_threads()) {
3604 workers()->threads_do(tc);
3605 }
3606 tc->do_thread(_cmThread);
3607 _cg1r->threads_do(tc);
3608 if (G1StringDedup::is_enabled()) {
3609 G1StringDedup::threads_do(tc);
3610 }
3611 }
3612
3613 void G1CollectedHeap::print_tracing_info() const {
3614 // We'll overload this to mean "trace GC pause statistics."
3615 if (TraceYoungGenTime || TraceOldGenTime) {
3616 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3617 // to that.
3618 g1_policy()->print_tracing_info();
3619 }
3620 if (G1SummarizeRSetStats) {
3621 g1_rem_set()->print_summary_info();
3622 }
3623 if (G1SummarizeConcMark) {
3624 concurrent_mark()->print_summary_info();
3625 }
3626 g1_policy()->print_yg_surv_rate_info();
3627 SpecializationStats::print();
3628 }
3629
3630 #ifndef PRODUCT
3631 // Helpful for debugging RSet issues.
3632
3633 class PrintRSetsClosure : public HeapRegionClosure {
3634 private:
3635 const char* _msg;
3636 size_t _occupied_sum;
3637
3638 public:
3639 bool doHeapRegion(HeapRegion* r) {
3640 HeapRegionRemSet* hrrs = r->rem_set();
3641 size_t occupied = hrrs->occupied();
3642 _occupied_sum += occupied;
3643
3644 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3645 HR_FORMAT_PARAMS(r));
3646 if (occupied == 0) {
3647 gclog_or_tty->print_cr(" RSet is empty");
3648 } else {
3649 hrrs->print();
3650 }
3651 gclog_or_tty->print_cr("----------");
3652 return false;
3653 }
3654
3655 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3656 gclog_or_tty->cr();
3657 gclog_or_tty->print_cr("========================================");
3658 gclog_or_tty->print_cr("%s", msg);
3659 gclog_or_tty->cr();
3660 }
3661
3662 ~PrintRSetsClosure() {
3663 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3664 gclog_or_tty->print_cr("========================================");
3665 gclog_or_tty->cr();
3666 }
3667 };
3668
3669 void G1CollectedHeap::print_cset_rsets() {
3670 PrintRSetsClosure cl("Printing CSet RSets");
3671 collection_set_iterate(&cl);
3672 }
3673
3674 void G1CollectedHeap::print_all_rsets() {
3675 PrintRSetsClosure cl("Printing All RSets");;
3676 heap_region_iterate(&cl);
3677 }
3678 #endif // PRODUCT
3679
3680 G1CollectedHeap* G1CollectedHeap::heap() {
3681 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3682 "not a garbage-first heap");
3683 return _g1h;
3684 }
3685
3686 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3687 // always_do_update_barrier = false;
3688 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3689 // Fill TLAB's and such
3690 accumulate_statistics_all_tlabs();
3691 ensure_parsability(true);
3692
3693 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3694 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3695 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3696 }
3697 }
3698
3699 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3700
3701 if (G1SummarizeRSetStats &&
3702 (G1SummarizeRSetStatsPeriod > 0) &&
3703 // we are at the end of the GC. Total collections has already been increased.
3704 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3705 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3706 }
3707
3708 // FIXME: what is this about?
3709 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3710 // is set.
3711 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3712 "derived pointer present"));
3713 // always_do_update_barrier = true;
3714
3715 resize_all_tlabs();
3716
3717 // We have just completed a GC. Update the soft reference
3718 // policy with the new heap occupancy
3719 Universe::update_heap_info_at_gc();
3720 }
3721
3722 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3723 unsigned int gc_count_before,
3724 bool* succeeded,
3725 GCCause::Cause gc_cause) {
3726 assert_heap_not_locked_and_not_at_safepoint();
3727 g1_policy()->record_stop_world_start();
3728 VM_G1IncCollectionPause op(gc_count_before,
3729 word_size,
3730 false, /* should_initiate_conc_mark */
3731 g1_policy()->max_pause_time_ms(),
3732 gc_cause);
3733 VMThread::execute(&op);
3734
3735 HeapWord* result = op.result();
3736 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3737 assert(result == NULL || ret_succeeded,
3738 "the result should be NULL if the VM did not succeed");
3739 *succeeded = ret_succeeded;
3740
3741 assert_heap_not_locked();
3742 return result;
3743 }
3744
3745 void
3746 G1CollectedHeap::doConcurrentMark() {
3747 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3748 if (!_cmThread->in_progress()) {
3749 _cmThread->set_started();
3750 CGC_lock->notify();
3751 }
3752 }
3753
3754 size_t G1CollectedHeap::pending_card_num() {
3755 size_t extra_cards = 0;
3756 JavaThread *curr = Threads::first();
3757 while (curr != NULL) {
3758 DirtyCardQueue& dcq = curr->dirty_card_queue();
3759 extra_cards += dcq.size();
3760 curr = curr->next();
3761 }
3762 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3763 size_t buffer_size = dcqs.buffer_size();
3764 size_t buffer_num = dcqs.completed_buffers_num();
3765
3766 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3767 // in bytes - not the number of 'entries'. We need to convert
3768 // into a number of cards.
3769 return (buffer_size * buffer_num + extra_cards) / oopSize;
3770 }
3771
3772 size_t G1CollectedHeap::cards_scanned() {
3773 return g1_rem_set()->cardsScanned();
3774 }
3775
3776 void
3777 G1CollectedHeap::setup_surviving_young_words() {
3778 assert(_surviving_young_words == NULL, "pre-condition");
3779 uint array_length = g1_policy()->young_cset_region_length();
3780 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3781 if (_surviving_young_words == NULL) {
3782 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3783 "Not enough space for young surv words summary.");
3784 }
3785 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3786 #ifdef ASSERT
3787 for (uint i = 0; i < array_length; ++i) {
3788 assert( _surviving_young_words[i] == 0, "memset above" );
3789 }
3790 #endif // !ASSERT
3791 }
3792
3793 void
3794 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3795 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3796 uint array_length = g1_policy()->young_cset_region_length();
3797 for (uint i = 0; i < array_length; ++i) {
3798 _surviving_young_words[i] += surv_young_words[i];
3799 }
3800 }
3801
3802 void
3803 G1CollectedHeap::cleanup_surviving_young_words() {
3804 guarantee( _surviving_young_words != NULL, "pre-condition" );
3805 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3806 _surviving_young_words = NULL;
3807 }
3808
3809 #ifdef ASSERT
3810 class VerifyCSetClosure: public HeapRegionClosure {
3811 public:
3812 bool doHeapRegion(HeapRegion* hr) {
3813 // Here we check that the CSet region's RSet is ready for parallel
3814 // iteration. The fields that we'll verify are only manipulated
3815 // when the region is part of a CSet and is collected. Afterwards,
3816 // we reset these fields when we clear the region's RSet (when the
3817 // region is freed) so they are ready when the region is
3818 // re-allocated. The only exception to this is if there's an
3819 // evacuation failure and instead of freeing the region we leave
3820 // it in the heap. In that case, we reset these fields during
3821 // evacuation failure handling.
3822 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3823
3824 // Here's a good place to add any other checks we'd like to
3825 // perform on CSet regions.
3826 return false;
3827 }
3828 };
3829 #endif // ASSERT
3830
3831 #if TASKQUEUE_STATS
3832 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3833 st->print_raw_cr("GC Task Stats");
3834 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3835 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3836 }
3837
3838 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3839 print_taskqueue_stats_hdr(st);
3840
3841 TaskQueueStats totals;
3842 const int n = workers() != NULL ? workers()->total_workers() : 1;
3843 for (int i = 0; i < n; ++i) {
3844 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3845 totals += task_queue(i)->stats;
3846 }
3847 st->print_raw("tot "); totals.print(st); st->cr();
3848
3849 DEBUG_ONLY(totals.verify());
3850 }
3851
3852 void G1CollectedHeap::reset_taskqueue_stats() {
3853 const int n = workers() != NULL ? workers()->total_workers() : 1;
3854 for (int i = 0; i < n; ++i) {
3855 task_queue(i)->stats.reset();
3856 }
3857 }
3858 #endif // TASKQUEUE_STATS
3859
3860 void G1CollectedHeap::log_gc_header() {
3861 if (!G1Log::fine()) {
3862 return;
3863 }
3864
3865 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3866
3867 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3868 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3869 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3870
3871 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3872 }
3873
3874 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3875 if (!G1Log::fine()) {
3876 return;
3877 }
3878
3879 if (G1Log::finer()) {
3880 if (evacuation_failed()) {
3881 gclog_or_tty->print(" (to-space exhausted)");
3882 }
3883 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3884 g1_policy()->phase_times()->note_gc_end();
3885 g1_policy()->phase_times()->print(pause_time_sec);
3886 g1_policy()->print_detailed_heap_transition();
3887 } else {
3888 if (evacuation_failed()) {
3889 gclog_or_tty->print("--");
3890 }
3891 g1_policy()->print_heap_transition();
3892 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3893 }
3894 gclog_or_tty->flush();
3895 }
3896
3897 bool
3898 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3899 assert_at_safepoint(true /* should_be_vm_thread */);
3900 guarantee(!is_gc_active(), "collection is not reentrant");
3901
3902 if (GC_locker::check_active_before_gc()) {
3903 return false;
3904 }
3905
3906 _gc_timer_stw->register_gc_start();
3907
3908 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3909
3910 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3911 ResourceMark rm;
3912
3913 print_heap_before_gc();
3914 trace_heap_before_gc(_gc_tracer_stw);
3915
3916 verify_region_sets_optional();
3917 verify_dirty_young_regions();
3918
3919 // This call will decide whether this pause is an initial-mark
3920 // pause. If it is, during_initial_mark_pause() will return true
3921 // for the duration of this pause.
3922 g1_policy()->decide_on_conc_mark_initiation();
3923
3924 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3925 assert(!g1_policy()->during_initial_mark_pause() ||
3926 g1_policy()->gcs_are_young(), "sanity");
3927
3928 // We also do not allow mixed GCs during marking.
3929 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3930
3931 // Record whether this pause is an initial mark. When the current
3932 // thread has completed its logging output and it's safe to signal
3933 // the CM thread, the flag's value in the policy has been reset.
3934 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3935
3936 // Inner scope for scope based logging, timers, and stats collection
3937 {
3938 EvacuationInfo evacuation_info;
3939
3940 if (g1_policy()->during_initial_mark_pause()) {
3941 // We are about to start a marking cycle, so we increment the
3942 // full collection counter.
3943 increment_old_marking_cycles_started();
3944 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3945 }
3946
3947 _gc_tracer_stw->report_yc_type(yc_type());
3948
3949 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3950
3951 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3952 workers()->active_workers() : 1);
3953 double pause_start_sec = os::elapsedTime();
3954 g1_policy()->phase_times()->note_gc_start(active_workers);
3955 log_gc_header();
3956
3957 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3958 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3959
3960 // If the secondary_free_list is not empty, append it to the
3961 // free_list. No need to wait for the cleanup operation to finish;
3962 // the region allocation code will check the secondary_free_list
3963 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3964 // set, skip this step so that the region allocation code has to
3965 // get entries from the secondary_free_list.
3966 if (!G1StressConcRegionFreeing) {
3967 append_secondary_free_list_if_not_empty_with_lock();
3968 }
3969
3970 assert(check_young_list_well_formed(), "young list should be well formed");
3971 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3972 "sanity check");
3973
3974 // Don't dynamically change the number of GC threads this early. A value of
3975 // 0 is used to indicate serial work. When parallel work is done,
3976 // it will be set.
3977
3978 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3979 IsGCActiveMark x;
3980
3981 gc_prologue(false);
3982 increment_total_collections(false /* full gc */);
3983 increment_gc_time_stamp();
3984
3985 verify_before_gc();
3986
3987 check_bitmaps("GC Start");
3988
3989 COMPILER2_PRESENT(DerivedPointerTable::clear());
3990
3991 // Please see comment in g1CollectedHeap.hpp and
3992 // G1CollectedHeap::ref_processing_init() to see how
3993 // reference processing currently works in G1.
3994
3995 // Enable discovery in the STW reference processor
3996 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3997 true /*verify_no_refs*/);
3998
3999 {
4000 // We want to temporarily turn off discovery by the
4001 // CM ref processor, if necessary, and turn it back on
4002 // on again later if we do. Using a scoped
4003 // NoRefDiscovery object will do this.
4004 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4005
4006 // Forget the current alloc region (we might even choose it to be part
4007 // of the collection set!).
4008 release_mutator_alloc_region();
4009
4010 // We should call this after we retire the mutator alloc
4011 // region(s) so that all the ALLOC / RETIRE events are generated
4012 // before the start GC event.
4013 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4014
4015 // This timing is only used by the ergonomics to handle our pause target.
4016 // It is unclear why this should not include the full pause. We will
4017 // investigate this in CR 7178365.
4018 //
4019 // Preserving the old comment here if that helps the investigation:
4020 //
4021 // The elapsed time induced by the start time below deliberately elides
4022 // the possible verification above.
4023 double sample_start_time_sec = os::elapsedTime();
4024
4025 #if YOUNG_LIST_VERBOSE
4026 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4027 _young_list->print();
4028 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4029 #endif // YOUNG_LIST_VERBOSE
4030
4031 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4032
4033 double scan_wait_start = os::elapsedTime();
4034 // We have to wait until the CM threads finish scanning the
4035 // root regions as it's the only way to ensure that all the
4036 // objects on them have been correctly scanned before we start
4037 // moving them during the GC.
4038 bool waited = _cm->root_regions()->wait_until_scan_finished();
4039 double wait_time_ms = 0.0;
4040 if (waited) {
4041 double scan_wait_end = os::elapsedTime();
4042 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4043 }
4044 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4045
4046 #if YOUNG_LIST_VERBOSE
4047 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4048 _young_list->print();
4049 #endif // YOUNG_LIST_VERBOSE
4050
4051 if (g1_policy()->during_initial_mark_pause()) {
4052 concurrent_mark()->checkpointRootsInitialPre();
4053 }
4054
4055 #if YOUNG_LIST_VERBOSE
4056 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4057 _young_list->print();
4058 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4059 #endif // YOUNG_LIST_VERBOSE
4060
4061 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4062
4063 _cm->note_start_of_gc();
4064 // We should not verify the per-thread SATB buffers given that
4065 // we have not filtered them yet (we'll do so during the
4066 // GC). We also call this after finalize_cset() to
4067 // ensure that the CSet has been finalized.
4068 _cm->verify_no_cset_oops(true /* verify_stacks */,
4069 true /* verify_enqueued_buffers */,
4070 false /* verify_thread_buffers */,
4071 true /* verify_fingers */);
4072
4073 if (_hr_printer.is_active()) {
4074 HeapRegion* hr = g1_policy()->collection_set();
4075 while (hr != NULL) {
4076 G1HRPrinter::RegionType type;
4077 if (!hr->is_young()) {
4078 type = G1HRPrinter::Old;
4079 } else if (hr->is_survivor()) {
4080 type = G1HRPrinter::Survivor;
4081 } else {
4082 type = G1HRPrinter::Eden;
4083 }
4084 _hr_printer.cset(hr);
4085 hr = hr->next_in_collection_set();
4086 }
4087 }
4088
4089 #ifdef ASSERT
4090 VerifyCSetClosure cl;
4091 collection_set_iterate(&cl);
4092 #endif // ASSERT
4093
4094 setup_surviving_young_words();
4095
4096 // Initialize the GC alloc regions.
4097 init_gc_alloc_regions(evacuation_info);
4098
4099 // Actually do the work...
4100 evacuate_collection_set(evacuation_info);
4101
4102 // We do this to mainly verify the per-thread SATB buffers
4103 // (which have been filtered by now) since we didn't verify
4104 // them earlier. No point in re-checking the stacks / enqueued
4105 // buffers given that the CSet has not changed since last time
4106 // we checked.
4107 _cm->verify_no_cset_oops(false /* verify_stacks */,
4108 false /* verify_enqueued_buffers */,
4109 true /* verify_thread_buffers */,
4110 true /* verify_fingers */);
4111
4112 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4113 g1_policy()->clear_collection_set();
4114
4115 cleanup_surviving_young_words();
4116
4117 // Start a new incremental collection set for the next pause.
4118 g1_policy()->start_incremental_cset_building();
4119
4120 clear_cset_fast_test();
4121
4122 _young_list->reset_sampled_info();
4123
4124 // Don't check the whole heap at this point as the
4125 // GC alloc regions from this pause have been tagged
4126 // as survivors and moved on to the survivor list.
4127 // Survivor regions will fail the !is_young() check.
4128 assert(check_young_list_empty(false /* check_heap */),
4129 "young list should be empty");
4130
4131 #if YOUNG_LIST_VERBOSE
4132 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4133 _young_list->print();
4134 #endif // YOUNG_LIST_VERBOSE
4135
4136 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4137 _young_list->first_survivor_region(),
4138 _young_list->last_survivor_region());
4139
4140 _young_list->reset_auxilary_lists();
4141
4142 if (evacuation_failed()) {
4143 _summary_bytes_used = recalculate_used();
4144 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4145 for (uint i = 0; i < n_queues; i++) {
4146 if (_evacuation_failed_info_array[i].has_failed()) {
4147 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4148 }
4149 }
4150 } else {
4151 // The "used" of the the collection set have already been subtracted
4152 // when they were freed. Add in the bytes evacuated.
4153 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4154 }
4155
4156 if (g1_policy()->during_initial_mark_pause()) {
4157 // We have to do this before we notify the CM threads that
4158 // they can start working to make sure that all the
4159 // appropriate initialization is done on the CM object.
4160 concurrent_mark()->checkpointRootsInitialPost();
4161 set_marking_started();
4162 // Note that we don't actually trigger the CM thread at
4163 // this point. We do that later when we're sure that
4164 // the current thread has completed its logging output.
4165 }
4166
4167 allocate_dummy_regions();
4168
4169 #if YOUNG_LIST_VERBOSE
4170 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4171 _young_list->print();
4172 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4173 #endif // YOUNG_LIST_VERBOSE
4174
4175 init_mutator_alloc_region();
4176
4177 {
4178 size_t expand_bytes = g1_policy()->expansion_amount();
4179 if (expand_bytes > 0) {
4180 size_t bytes_before = capacity();
4181 // No need for an ergo verbose message here,
4182 // expansion_amount() does this when it returns a value > 0.
4183 if (!expand(expand_bytes)) {
4184 // We failed to expand the heap so let's verify that
4185 // committed/uncommitted amount match the backing store
4186 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4187 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4188 }
4189 }
4190 }
4191
4192 // We redo the verification but now wrt to the new CSet which
4193 // has just got initialized after the previous CSet was freed.
4194 _cm->verify_no_cset_oops(true /* verify_stacks */,
4195 true /* verify_enqueued_buffers */,
4196 true /* verify_thread_buffers */,
4197 true /* verify_fingers */);
4198 _cm->note_end_of_gc();
4199
4200 // This timing is only used by the ergonomics to handle our pause target.
4201 // It is unclear why this should not include the full pause. We will
4202 // investigate this in CR 7178365.
4203 double sample_end_time_sec = os::elapsedTime();
4204 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4205 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4206
4207 MemoryService::track_memory_usage();
4208
4209 // In prepare_for_verify() below we'll need to scan the deferred
4210 // update buffers to bring the RSets up-to-date if
4211 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4212 // the update buffers we'll probably need to scan cards on the
4213 // regions we just allocated to (i.e., the GC alloc
4214 // regions). However, during the last GC we called
4215 // set_saved_mark() on all the GC alloc regions, so card
4216 // scanning might skip the [saved_mark_word()...top()] area of
4217 // those regions (i.e., the area we allocated objects into
4218 // during the last GC). But it shouldn't. Given that
4219 // saved_mark_word() is conditional on whether the GC time stamp
4220 // on the region is current or not, by incrementing the GC time
4221 // stamp here we invalidate all the GC time stamps on all the
4222 // regions and saved_mark_word() will simply return top() for
4223 // all the regions. This is a nicer way of ensuring this rather
4224 // than iterating over the regions and fixing them. In fact, the
4225 // GC time stamp increment here also ensures that
4226 // saved_mark_word() will return top() between pauses, i.e.,
4227 // during concurrent refinement. So we don't need the
4228 // is_gc_active() check to decided which top to use when
4229 // scanning cards (see CR 7039627).
4230 increment_gc_time_stamp();
4231
4232 verify_after_gc();
4233 check_bitmaps("GC End");
4234
4235 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4236 ref_processor_stw()->verify_no_references_recorded();
4237
4238 // CM reference discovery will be re-enabled if necessary.
4239 }
4240
4241 // We should do this after we potentially expand the heap so
4242 // that all the COMMIT events are generated before the end GC
4243 // event, and after we retire the GC alloc regions so that all
4244 // RETIRE events are generated before the end GC event.
4245 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4246
4247 if (mark_in_progress()) {
4248 concurrent_mark()->update_g1_committed();
4249 }
4250
4251 #ifdef TRACESPINNING
4252 ParallelTaskTerminator::print_termination_counts();
4253 #endif
4254
4255 gc_epilogue(false);
4256 }
4257
4258 // Print the remainder of the GC log output.
4259 log_gc_footer(os::elapsedTime() - pause_start_sec);
4260
4261 // It is not yet to safe to tell the concurrent mark to
4262 // start as we have some optional output below. We don't want the
4263 // output from the concurrent mark thread interfering with this
4264 // logging output either.
4265
4266 _hrs.verify_optional();
4267 verify_region_sets_optional();
4268
4269 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4270 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4271
4272 print_heap_after_gc();
4273 trace_heap_after_gc(_gc_tracer_stw);
4274
4275 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4276 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4277 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4278 // before any GC notifications are raised.
4279 g1mm()->update_sizes();
4280
4281 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4282 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4283 _gc_timer_stw->register_gc_end();
4284 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4285 }
4286 // It should now be safe to tell the concurrent mark thread to start
4287 // without its logging output interfering with the logging output
4288 // that came from the pause.
4289
4290 if (should_start_conc_mark) {
4291 // CAUTION: after the doConcurrentMark() call below,
4292 // the concurrent marking thread(s) could be running
4293 // concurrently with us. Make sure that anything after
4294 // this point does not assume that we are the only GC thread
4295 // running. Note: of course, the actual marking work will
4296 // not start until the safepoint itself is released in
4297 // SuspendibleThreadSet::desynchronize().
4298 doConcurrentMark();
4299 }
4300
4301 return true;
4302 }
4303
4304 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4305 {
4306 size_t gclab_word_size;
4307 switch (purpose) {
4308 case GCAllocForSurvived:
4309 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4310 break;
4311 case GCAllocForTenured:
4312 gclab_word_size = _old_plab_stats.desired_plab_sz();
4313 break;
4314 default:
4315 assert(false, "unknown GCAllocPurpose");
4316 gclab_word_size = _old_plab_stats.desired_plab_sz();
4317 break;
4318 }
4319
4320 // Prevent humongous PLAB sizes for two reasons:
4321 // * PLABs are allocated using a similar paths as oops, but should
4322 // never be in a humongous region
4323 // * Allowing humongous PLABs needlessly churns the region free lists
4324 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4325 }
4326
4327 void G1CollectedHeap::init_mutator_alloc_region() {
4328 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4329 _mutator_alloc_region.init();
4330 }
4331
4332 void G1CollectedHeap::release_mutator_alloc_region() {
4333 _mutator_alloc_region.release();
4334 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4335 }
4336
4337 void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) {
4338 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4339 _retained_old_gc_alloc_region = NULL;
4340
4341 // We will discard the current GC alloc region if:
4342 // a) it's in the collection set (it can happen!),
4343 // b) it's already full (no point in using it),
4344 // c) it's empty (this means that it was emptied during
4345 // a cleanup and it should be on the free list now), or
4346 // d) it's humongous (this means that it was emptied
4347 // during a cleanup and was added to the free list, but
4348 // has been subsequently used to allocate a humongous
4349 // object that may be less than the region size).
4350 if (retained_region != NULL &&
4351 !retained_region->in_collection_set() &&
4352 !(retained_region->top() == retained_region->end()) &&
4353 !retained_region->is_empty() &&
4354 !retained_region->isHumongous()) {
4355 retained_region->record_top_and_timestamp();
4356 // The retained region was added to the old region set when it was
4357 // retired. We have to remove it now, since we don't allow regions
4358 // we allocate to in the region sets. We'll re-add it later, when
4359 // it's retired again.
4360 _old_set.remove(retained_region);
4361 bool during_im = g1_policy()->during_initial_mark_pause();
4362 retained_region->note_start_of_copying(during_im);
4363 _old_gc_alloc_region.set(retained_region);
4364 _hr_printer.reuse(retained_region);
4365 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4366 }
4367 }
4368
4369 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4370 assert_at_safepoint(true /* should_be_vm_thread */);
4371
4372 _survivor_gc_alloc_region.init();
4373 _old_gc_alloc_region.init();
4374
4375 use_retained_old_gc_alloc_region(evacuation_info);
4376 }
4377
4378 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4379 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4380 _old_gc_alloc_region.count());
4381 _survivor_gc_alloc_region.release();
4382 // If we have an old GC alloc region to release, we'll save it in
4383 // _retained_old_gc_alloc_region. If we don't
4384 // _retained_old_gc_alloc_region will become NULL. This is what we
4385 // want either way so no reason to check explicitly for either
4386 // condition.
4387 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4388
4389 if (ResizePLAB) {
4390 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4391 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4392 }
4393 }
4394
4395 void G1CollectedHeap::abandon_gc_alloc_regions() {
4396 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4397 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4398 _retained_old_gc_alloc_region = NULL;
4399 }
4400
4401 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4402 _drain_in_progress = false;
4403 set_evac_failure_closure(cl);
4404 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4405 }
4406
4407 void G1CollectedHeap::finalize_for_evac_failure() {
4408 assert(_evac_failure_scan_stack != NULL &&
4409 _evac_failure_scan_stack->length() == 0,
4410 "Postcondition");
4411 assert(!_drain_in_progress, "Postcondition");
4412 delete _evac_failure_scan_stack;
4413 _evac_failure_scan_stack = NULL;
4414 }
4415
4416 void G1CollectedHeap::remove_self_forwarding_pointers() {
4417 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4418
4419 double remove_self_forwards_start = os::elapsedTime();
4420
4421 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4422
4423 if (G1CollectedHeap::use_parallel_gc_threads()) {
4424 set_par_threads();
4425 workers()->run_task(&rsfp_task);
4426 set_par_threads(0);
4427 } else {
4428 rsfp_task.work(0);
4429 }
4430
4431 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4432
4433 // Reset the claim values in the regions in the collection set.
4434 reset_cset_heap_region_claim_values();
4435
4436 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4437
4438 // Now restore saved marks, if any.
4439 assert(_objs_with_preserved_marks.size() ==
4440 _preserved_marks_of_objs.size(), "Both or none.");
4441 while (!_objs_with_preserved_marks.is_empty()) {
4442 oop obj = _objs_with_preserved_marks.pop();
4443 markOop m = _preserved_marks_of_objs.pop();
4444 obj->set_mark(m);
4445 }
4446 _objs_with_preserved_marks.clear(true);
4447 _preserved_marks_of_objs.clear(true);
4448
4449 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4450 }
4451
4452 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4453 _evac_failure_scan_stack->push(obj);
4454 }
4455
4456 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4457 assert(_evac_failure_scan_stack != NULL, "precondition");
4458
4459 while (_evac_failure_scan_stack->length() > 0) {
4460 oop obj = _evac_failure_scan_stack->pop();
4461 _evac_failure_closure->set_region(heap_region_containing(obj));
4462 obj->oop_iterate_backwards(_evac_failure_closure);
4463 }
4464 }
4465
4466 oop
4467 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4468 oop old) {
4469 assert(obj_in_cs(old),
4470 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4471 (HeapWord*) old));
4472 markOop m = old->mark();
4473 oop forward_ptr = old->forward_to_atomic(old);
4474 if (forward_ptr == NULL) {
4475 // Forward-to-self succeeded.
4476 assert(_par_scan_state != NULL, "par scan state");
4477 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4478 uint queue_num = _par_scan_state->queue_num();
4479
4480 _evacuation_failed = true;
4481 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4482 if (_evac_failure_closure != cl) {
4483 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4484 assert(!_drain_in_progress,
4485 "Should only be true while someone holds the lock.");
4486 // Set the global evac-failure closure to the current thread's.
4487 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4488 set_evac_failure_closure(cl);
4489 // Now do the common part.
4490 handle_evacuation_failure_common(old, m);
4491 // Reset to NULL.
4492 set_evac_failure_closure(NULL);
4493 } else {
4494 // The lock is already held, and this is recursive.
4495 assert(_drain_in_progress, "This should only be the recursive case.");
4496 handle_evacuation_failure_common(old, m);
4497 }
4498 return old;
4499 } else {
4500 // Forward-to-self failed. Either someone else managed to allocate
4501 // space for this object (old != forward_ptr) or they beat us in
4502 // self-forwarding it (old == forward_ptr).
4503 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4504 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4505 "should not be in the CSet",
4506 (HeapWord*) old, (HeapWord*) forward_ptr));
4507 return forward_ptr;
4508 }
4509 }
4510
4511 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4512 preserve_mark_if_necessary(old, m);
4513
4514 HeapRegion* r = heap_region_containing(old);
4515 if (!r->evacuation_failed()) {
4516 r->set_evacuation_failed(true);
4517 _hr_printer.evac_failure(r);
4518 }
4519
4520 push_on_evac_failure_scan_stack(old);
4521
4522 if (!_drain_in_progress) {
4523 // prevent recursion in copy_to_survivor_space()
4524 _drain_in_progress = true;
4525 drain_evac_failure_scan_stack();
4526 _drain_in_progress = false;
4527 }
4528 }
4529
4530 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4531 assert(evacuation_failed(), "Oversaving!");
4532 // We want to call the "for_promotion_failure" version only in the
4533 // case of a promotion failure.
4534 if (m->must_be_preserved_for_promotion_failure(obj)) {
4535 _objs_with_preserved_marks.push(obj);
4536 _preserved_marks_of_objs.push(m);
4537 }
4538 }
4539
4540 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4541 size_t word_size) {
4542 if (purpose == GCAllocForSurvived) {
4543 HeapWord* result = survivor_attempt_allocation(word_size);
4544 if (result != NULL) {
4545 return result;
4546 } else {
4547 // Let's try to allocate in the old gen in case we can fit the
4548 // object there.
4549 return old_attempt_allocation(word_size);
4550 }
4551 } else {
4552 assert(purpose == GCAllocForTenured, "sanity");
4553 HeapWord* result = old_attempt_allocation(word_size);
4554 if (result != NULL) {
4555 return result;
4556 } else {
4557 // Let's try to allocate in the survivors in case we can fit the
4558 // object there.
4559 return survivor_attempt_allocation(word_size);
4560 }
4561 }
4562
4563 ShouldNotReachHere();
4564 // Trying to keep some compilers happy.
4565 return NULL;
4566 }
4567
4568 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4569 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4570
4571 void G1ParCopyHelper::mark_object(oop obj) {
4572 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4573
4574 // We know that the object is not moving so it's safe to read its size.
4575 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4576 }
4577
4578 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4579 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4580 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4581 assert(from_obj != to_obj, "should not be self-forwarded");
4582
4583 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4584 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4585
4586 // The object might be in the process of being copied by another
4587 // worker so we cannot trust that its to-space image is
4588 // well-formed. So we have to read its size from its from-space
4589 // image which we know should not be changing.
4590 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4591 }
4592
4593 template <class T>
4594 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4595 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4596 _scanned_klass->record_modified_oops();
4597 }
4598 }
4599
4600 template <G1Barrier barrier, G1Mark do_mark_object>
4601 template <class T>
4602 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4603 T heap_oop = oopDesc::load_heap_oop(p);
4604
4605 if (oopDesc::is_null(heap_oop)) {
4606 return;
4607 }
4608
4609 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4610
4611 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4612
4613 if (_g1->in_cset_fast_test(obj)) {
4614 oop forwardee;
4615 if (obj->is_forwarded()) {
4616 forwardee = obj->forwardee();
4617 } else {
4618 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4619 }
4620 assert(forwardee != NULL, "forwardee should not be NULL");
4621 oopDesc::encode_store_heap_oop(p, forwardee);
4622 if (do_mark_object != G1MarkNone && forwardee != obj) {
4623 // If the object is self-forwarded we don't need to explicitly
4624 // mark it, the evacuation failure protocol will do so.
4625 mark_forwarded_object(obj, forwardee);
4626 }
4627
4628 if (barrier == G1BarrierKlass) {
4629 do_klass_barrier(p, forwardee);
4630 }
4631 } else {
4632 // The object is not in collection set. If we're a root scanning
4633 // closure during an initial mark pause then attempt to mark the object.
4634 if (do_mark_object == G1MarkFromRoot) {
4635 mark_object(obj);
4636 }
4637 }
4638
4639 if (barrier == G1BarrierEvac) {
4640 _par_scan_state->update_rs(_from, p, _worker_id);
4641 }
4642 }
4643
4644 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4645 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4646
4647 class G1ParEvacuateFollowersClosure : public VoidClosure {
4648 protected:
4649 G1CollectedHeap* _g1h;
4650 G1ParScanThreadState* _par_scan_state;
4651 RefToScanQueueSet* _queues;
4652 ParallelTaskTerminator* _terminator;
4653
4654 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4655 RefToScanQueueSet* queues() { return _queues; }
4656 ParallelTaskTerminator* terminator() { return _terminator; }
4657
4658 public:
4659 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4660 G1ParScanThreadState* par_scan_state,
4661 RefToScanQueueSet* queues,
4662 ParallelTaskTerminator* terminator)
4663 : _g1h(g1h), _par_scan_state(par_scan_state),
4664 _queues(queues), _terminator(terminator) {}
4665
4666 void do_void();
4667
4668 private:
4669 inline bool offer_termination();
4670 };
4671
4672 bool G1ParEvacuateFollowersClosure::offer_termination() {
4673 G1ParScanThreadState* const pss = par_scan_state();
4674 pss->start_term_time();
4675 const bool res = terminator()->offer_termination();
4676 pss->end_term_time();
4677 return res;
4678 }
4679
4680 void G1ParEvacuateFollowersClosure::do_void() {
4681 G1ParScanThreadState* const pss = par_scan_state();
4682 pss->trim_queue();
4683 do {
4684 pss->steal_and_trim_queue(queues());
4685 } while (!offer_termination());
4686 }
4687
4688 class G1KlassScanClosure : public KlassClosure {
4689 G1ParCopyHelper* _closure;
4690 bool _process_only_dirty;
4691 int _count;
4692 public:
4693 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4694 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4695 void do_klass(Klass* klass) {
4696 // If the klass has not been dirtied we know that there's
4697 // no references into the young gen and we can skip it.
4698 if (!_process_only_dirty || klass->has_modified_oops()) {
4699 // Clean the klass since we're going to scavenge all the metadata.
4700 klass->clear_modified_oops();
4701
4702 // Tell the closure that this klass is the Klass to scavenge
4703 // and is the one to dirty if oops are left pointing into the young gen.
4704 _closure->set_scanned_klass(klass);
4705
4706 klass->oops_do(_closure);
4707
4708 _closure->set_scanned_klass(NULL);
4709 }
4710 _count++;
4711 }
4712 };
4713
4714 class G1ParTask : public AbstractGangTask {
4715 protected:
4716 G1CollectedHeap* _g1h;
4717 RefToScanQueueSet *_queues;
4718 ParallelTaskTerminator _terminator;
4719 uint _n_workers;
4720
4721 Mutex _stats_lock;
4722 Mutex* stats_lock() { return &_stats_lock; }
4723
4724 size_t getNCards() {
4725 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4726 / G1BlockOffsetSharedArray::N_bytes;
4727 }
4728
4729 public:
4730 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4731 : AbstractGangTask("G1 collection"),
4732 _g1h(g1h),
4733 _queues(task_queues),
4734 _terminator(0, _queues),
4735 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4736 {}
4737
4738 RefToScanQueueSet* queues() { return _queues; }
4739
4740 RefToScanQueue *work_queue(int i) {
4741 return queues()->queue(i);
4742 }
4743
4744 ParallelTaskTerminator* terminator() { return &_terminator; }
4745
4746 virtual void set_for_termination(int active_workers) {
4747 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4748 // in the young space (_par_seq_tasks) in the G1 heap
4749 // for SequentialSubTasksDone.
4750 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4751 // both of which need setting by set_n_termination().
4752 _g1h->SharedHeap::set_n_termination(active_workers);
4753 _g1h->set_n_termination(active_workers);
4754 terminator()->reset_for_reuse(active_workers);
4755 _n_workers = active_workers;
4756 }
4757
4758 // Helps out with CLD processing.
4759 //
4760 // During InitialMark we need to:
4761 // 1) Scavenge all CLDs for the young GC.
4762 // 2) Mark all objects directly reachable from strong CLDs.
4763 template <G1Mark do_mark_object>
4764 class G1CLDClosure : public CLDClosure {
4765 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4766 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4767 G1KlassScanClosure _klass_in_cld_closure;
4768 bool _claim;
4769
4770 public:
4771 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4772 bool only_young, bool claim)
4773 : _oop_closure(oop_closure),
4774 _oop_in_klass_closure(oop_closure->g1(),
4775 oop_closure->pss(),
4776 oop_closure->rp()),
4777 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4778 _claim(claim) {
4779
4780 }
4781
4782 void do_cld(ClassLoaderData* cld) {
4783 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4784 }
4785 };
4786
4787 class G1CodeBlobClosure: public CodeBlobClosure {
4788 OopClosure* _f;
4789
4790 public:
4791 G1CodeBlobClosure(OopClosure* f) : _f(f) {}
4792 void do_code_blob(CodeBlob* blob) {
4793 nmethod* that = blob->as_nmethod_or_null();
4794 if (that != NULL) {
4795 if (!that->test_set_oops_do_mark()) {
4796 that->oops_do(_f);
4797 that->fix_oop_relocations();
4798 }
4799 }
4800 }
4801 };
4802
4803 void work(uint worker_id) {
4804 if (worker_id >= _n_workers) return; // no work needed this round
4805
4806 double start_time_ms = os::elapsedTime() * 1000.0;
4807 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4808
4809 {
4810 ResourceMark rm;
4811 HandleMark hm;
4812
4813 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4814
4815 G1ParScanThreadState pss(_g1h, worker_id, rp);
4816 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4817
4818 pss.set_evac_failure_closure(&evac_failure_cl);
4819
4820 bool only_young = _g1h->g1_policy()->gcs_are_young();
4821
4822 // Non-IM young GC.
4823 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4824 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4825 only_young, // Only process dirty klasses.
4826 false); // No need to claim CLDs.
4827 // IM young GC.
4828 // Strong roots closures.
4829 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4830 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4831 false, // Process all klasses.
4832 true); // Need to claim CLDs.
4833 // Weak roots closures.
4834 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4835 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4836 false, // Process all klasses.
4837 true); // Need to claim CLDs.
4838
4839 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4840 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4841 // IM Weak code roots are handled later.
4842
4843 OopClosure* strong_root_cl;
4844 OopClosure* weak_root_cl;
4845 CLDClosure* strong_cld_cl;
4846 CLDClosure* weak_cld_cl;
4847 CodeBlobClosure* strong_code_cl;
4848
4849 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4850 // We also need to mark copied objects.
4851 strong_root_cl = &scan_mark_root_cl;
4852 weak_root_cl = &scan_mark_weak_root_cl;
4853 strong_cld_cl = &scan_mark_cld_cl;
4854 weak_cld_cl = &scan_mark_weak_cld_cl;
4855 strong_code_cl = &scan_mark_code_cl;
4856 } else {
4857 strong_root_cl = &scan_only_root_cl;
4858 weak_root_cl = &scan_only_root_cl;
4859 strong_cld_cl = &scan_only_cld_cl;
4860 weak_cld_cl = &scan_only_cld_cl;
4861 strong_code_cl = &scan_only_code_cl;
4862 }
4863
4864
4865 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4866
4867 pss.start_strong_roots();
4868 _g1h->g1_process_roots(strong_root_cl,
4869 weak_root_cl,
4870 &push_heap_rs_cl,
4871 strong_cld_cl,
4872 weak_cld_cl,
4873 strong_code_cl,
4874 worker_id);
4875
4876 pss.end_strong_roots();
4877
4878 {
4879 double start = os::elapsedTime();
4880 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4881 evac.do_void();
4882 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4883 double term_ms = pss.term_time()*1000.0;
4884 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4885 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4886 }
4887 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4888 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4889
4890 if (ParallelGCVerbose) {
4891 MutexLocker x(stats_lock());
4892 pss.print_termination_stats(worker_id);
4893 }
4894
4895 assert(pss.queue_is_empty(), "should be empty");
4896
4897 // Close the inner scope so that the ResourceMark and HandleMark
4898 // destructors are executed here and are included as part of the
4899 // "GC Worker Time".
4900 }
4901
4902 double end_time_ms = os::elapsedTime() * 1000.0;
4903 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4904 }
4905 };
4906
4907 // *** Common G1 Evacuation Stuff
4908
4909 // This method is run in a GC worker.
4910
4911 void
4912 G1CollectedHeap::
4913 g1_process_roots(OopClosure* scan_non_heap_roots,
4914 OopClosure* scan_non_heap_weak_roots,
4915 OopsInHeapRegionClosure* scan_rs,
4916 CLDClosure* scan_strong_clds,
4917 CLDClosure* scan_weak_clds,
4918 CodeBlobClosure* scan_strong_code,
4919 uint worker_i) {
4920
4921 // First scan the shared roots.
4922 double ext_roots_start = os::elapsedTime();
4923 double closure_app_time_sec = 0.0;
4924
4925 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4926
4927 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4928 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4929
4930 process_roots(false, // no scoping; this is parallel code
4931 SharedHeap::SO_None,
4932 &buf_scan_non_heap_roots,
4933 &buf_scan_non_heap_weak_roots,
4934 scan_strong_clds,
4935 // Initial Mark handles the weak CLDs separately.
4936 (during_im ? NULL : scan_weak_clds),
4937 scan_strong_code);
4938
4939 // Now the CM ref_processor roots.
4940 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4941 // We need to treat the discovered reference lists of the
4942 // concurrent mark ref processor as roots and keep entries
4943 // (which are added by the marking threads) on them live
4944 // until they can be processed at the end of marking.
4945 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4946 }
4947
4948 if (during_im) {
4949 // Barrier to make sure all workers passed
4950 // the strong CLD and strong nmethods phases.
4951 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4952
4953 // Now take the complement of the strong CLDs.
4954 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4955 }
4956
4957 // Finish up any enqueued closure apps (attributed as object copy time).
4958 buf_scan_non_heap_roots.done();
4959 buf_scan_non_heap_weak_roots.done();
4960
4961 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4962 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4963
4964 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4965
4966 double ext_root_time_ms =
4967 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4968
4969 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4970
4971 // During conc marking we have to filter the per-thread SATB buffers
4972 // to make sure we remove any oops into the CSet (which will show up
4973 // as implicitly live).
4974 double satb_filtering_ms = 0.0;
4975 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4976 if (mark_in_progress()) {
4977 double satb_filter_start = os::elapsedTime();
4978
4979 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4980
4981 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4982 }
4983 }
4984 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4985
4986 // Now scan the complement of the collection set.
4987 MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations);
4988
4989 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4990
4991 _process_strong_tasks->all_tasks_completed();
4992 }
4993
4994 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4995 private:
4996 BoolObjectClosure* _is_alive;
4997 int _initial_string_table_size;
4998 int _initial_symbol_table_size;
4999
5000 bool _process_strings;
5001 int _strings_processed;
5002 int _strings_removed;
5003
5004 bool _process_symbols;
5005 int _symbols_processed;
5006 int _symbols_removed;
5007
5008 bool _do_in_parallel;
5009 public:
5010 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5011 AbstractGangTask("String/Symbol Unlinking"),
5012 _is_alive(is_alive),
5013 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5014 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5015 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5016
5017 _initial_string_table_size = StringTable::the_table()->table_size();
5018 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5019 if (process_strings) {
5020 StringTable::clear_parallel_claimed_index();
5021 }
5022 if (process_symbols) {
5023 SymbolTable::clear_parallel_claimed_index();
5024 }
5025 }
5026
5027 ~G1StringSymbolTableUnlinkTask() {
5028 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5029 err_msg("claim value %d after unlink less than initial string table size %d",
5030 StringTable::parallel_claimed_index(), _initial_string_table_size));
5031 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5032 err_msg("claim value %d after unlink less than initial symbol table size %d",
5033 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5034
5035 if (G1TraceStringSymbolTableScrubbing) {
5036 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5037 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5038 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5039 strings_processed(), strings_removed(),
5040 symbols_processed(), symbols_removed());
5041 }
5042 }
5043
5044 void work(uint worker_id) {
5045 if (_do_in_parallel) {
5046 int strings_processed = 0;
5047 int strings_removed = 0;
5048 int symbols_processed = 0;
5049 int symbols_removed = 0;
5050 if (_process_strings) {
5051 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5052 Atomic::add(strings_processed, &_strings_processed);
5053 Atomic::add(strings_removed, &_strings_removed);
5054 }
5055 if (_process_symbols) {
5056 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5057 Atomic::add(symbols_processed, &_symbols_processed);
5058 Atomic::add(symbols_removed, &_symbols_removed);
5059 }
5060 } else {
5061 if (_process_strings) {
5062 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5063 }
5064 if (_process_symbols) {
5065 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5066 }
5067 }
5068 }
5069
5070 size_t strings_processed() const { return (size_t)_strings_processed; }
5071 size_t strings_removed() const { return (size_t)_strings_removed; }
5072
5073 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5074 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5075 };
5076
5077 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
5078 private:
5079 static Monitor* _lock;
5080
5081 BoolObjectClosure* const _is_alive;
5082 const bool _unloading_occurred;
5083 const uint _num_workers;
5084
5085 // Variables used to claim nmethods.
5086 nmethod* _first_nmethod;
5087 volatile nmethod* _claimed_nmethod;
5088
5089 // The list of nmethods that need to be processed by the second pass.
5090 volatile nmethod* _postponed_list;
5091 volatile uint _num_entered_barrier;
5092
5093 public:
5094 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
5095 _is_alive(is_alive),
5096 _unloading_occurred(unloading_occurred),
5097 _num_workers(num_workers),
5098 _first_nmethod(NULL),
5099 _claimed_nmethod(NULL),
5100 _postponed_list(NULL),
5101 _num_entered_barrier(0)
5102 {
5103 nmethod::increase_unloading_clock();
5104 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
5105 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
5106 }
5107
5108 ~G1CodeCacheUnloadingTask() {
5109 CodeCache::verify_clean_inline_caches();
5110
5111 CodeCache::set_needs_cache_clean(false);
5112 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
5113
5114 CodeCache::verify_icholder_relocations();
5115 }
5116
5117 private:
5118 void add_to_postponed_list(nmethod* nm) {
5119 nmethod* old;
5120 do {
5121 old = (nmethod*)_postponed_list;
5122 nm->set_unloading_next(old);
5123 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
5124 }
5125
5126 void clean_nmethod(nmethod* nm) {
5127 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
5128
5129 if (postponed) {
5130 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
5131 add_to_postponed_list(nm);
5132 }
5133
5134 // Mark that this thread has been cleaned/unloaded.
5135 // After this call, it will be safe to ask if this nmethod was unloaded or not.
5136 nm->set_unloading_clock(nmethod::global_unloading_clock());
5137 }
5138
5139 void clean_nmethod_postponed(nmethod* nm) {
5140 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
5141 }
5142
5143 static const int MaxClaimNmethods = 16;
5144
5145 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
5146 nmethod* first;
5147 nmethod* last;
5148
5149 do {
5150 *num_claimed_nmethods = 0;
5151
5152 first = last = (nmethod*)_claimed_nmethod;
5153
5154 if (first != NULL) {
5155 for (int i = 0; i < MaxClaimNmethods; i++) {
5156 last = CodeCache::alive_nmethod(CodeCache::next(last));
5157
5158 if (last == NULL) {
5159 break;
5160 }
5161
5162 claimed_nmethods[i] = last;
5163 (*num_claimed_nmethods)++;
5164 }
5165 }
5166
5167 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
5168 }
5169
5170 nmethod* claim_postponed_nmethod() {
5171 nmethod* claim;
5172 nmethod* next;
5173
5174 do {
5175 claim = (nmethod*)_postponed_list;
5176 if (claim == NULL) {
5177 return NULL;
5178 }
5179
5180 next = claim->unloading_next();
5181
5182 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
5183
5184 return claim;
5185 }
5186
5187 public:
5188 // Mark that we're done with the first pass of nmethod cleaning.
5189 void barrier_mark(uint worker_id) {
5190 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5191 _num_entered_barrier++;
5192 if (_num_entered_barrier == _num_workers) {
5193 ml.notify_all();
5194 }
5195 }
5196
5197 // See if we have to wait for the other workers to
5198 // finish their first-pass nmethod cleaning work.
5199 void barrier_wait(uint worker_id) {
5200 if (_num_entered_barrier < _num_workers) {
5201 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5202 while (_num_entered_barrier < _num_workers) {
5203 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5204 }
5205 }
5206 }
5207
5208 // Cleaning and unloading of nmethods. Some work has to be postponed
5209 // to the second pass, when we know which nmethods survive.
5210 void work_first_pass(uint worker_id) {
5211 // The first nmethods is claimed by the first worker.
5212 if (worker_id == 0 && _first_nmethod != NULL) {
5213 clean_nmethod(_first_nmethod);
5214 _first_nmethod = NULL;
5215 }
5216
5217 int num_claimed_nmethods;
5218 nmethod* claimed_nmethods[MaxClaimNmethods];
5219
5220 while (true) {
5221 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5222
5223 if (num_claimed_nmethods == 0) {
5224 break;
5225 }
5226
5227 for (int i = 0; i < num_claimed_nmethods; i++) {
5228 clean_nmethod(claimed_nmethods[i]);
5229 }
5230 }
5231 }
5232
5233 void work_second_pass(uint worker_id) {
5234 nmethod* nm;
5235 // Take care of postponed nmethods.
5236 while ((nm = claim_postponed_nmethod()) != NULL) {
5237 clean_nmethod_postponed(nm);
5238 }
5239 }
5240 };
5241
5242 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5243
5244 class G1KlassCleaningTask : public StackObj {
5245 BoolObjectClosure* _is_alive;
5246 volatile jint _clean_klass_tree_claimed;
5247 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5248
5249 public:
5250 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5251 _is_alive(is_alive),
5252 _clean_klass_tree_claimed(0),
5253 _klass_iterator() {
5254 }
5255
5256 private:
5257 bool claim_clean_klass_tree_task() {
5258 if (_clean_klass_tree_claimed) {
5259 return false;
5260 }
5261
5262 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5263 }
5264
5265 InstanceKlass* claim_next_klass() {
5266 Klass* klass;
5267 do {
5268 klass =_klass_iterator.next_klass();
5269 } while (klass != NULL && !klass->oop_is_instance());
5270
5271 return (InstanceKlass*)klass;
5272 }
5273
5274 public:
5275
5276 void clean_klass(InstanceKlass* ik) {
5277 ik->clean_implementors_list(_is_alive);
5278 ik->clean_method_data(_is_alive);
5279
5280 // G1 specific cleanup work that has
5281 // been moved here to be done in parallel.
5282 ik->clean_dependent_nmethods();
5283 }
5284
5285 void work() {
5286 ResourceMark rm;
5287
5288 // One worker will clean the subklass/sibling klass tree.
5289 if (claim_clean_klass_tree_task()) {
5290 Klass::clean_subklass_tree(_is_alive);
5291 }
5292
5293 // All workers will help cleaning the classes,
5294 InstanceKlass* klass;
5295 while ((klass = claim_next_klass()) != NULL) {
5296 clean_klass(klass);
5297 }
5298 }
5299 };
5300
5301 // To minimize the remark pause times, the tasks below are done in parallel.
5302 class G1ParallelCleaningTask : public AbstractGangTask {
5303 private:
5304 G1StringSymbolTableUnlinkTask _string_symbol_task;
5305 G1CodeCacheUnloadingTask _code_cache_task;
5306 G1KlassCleaningTask _klass_cleaning_task;
5307
5308 public:
5309 // The constructor is run in the VMThread.
5310 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5311 AbstractGangTask("Parallel Cleaning"),
5312 _string_symbol_task(is_alive, process_strings, process_symbols),
5313 _code_cache_task(num_workers, is_alive, unloading_occurred),
5314 _klass_cleaning_task(is_alive) {
5315 }
5316
5317 // The parallel work done by all worker threads.
5318 void work(uint worker_id) {
5319 // Do first pass of code cache cleaning.
5320 _code_cache_task.work_first_pass(worker_id);
5321
5322 // Let the threads, mark that the first pass is done.
5323 _code_cache_task.barrier_mark(worker_id);
5324
5325 // Clean the Strings and Symbols.
5326 _string_symbol_task.work(worker_id);
5327
5328 // Wait for all workers to finish the first code cache cleaning pass.
5329 _code_cache_task.barrier_wait(worker_id);
5330
5331 // Do the second code cache cleaning work, which realize on
5332 // the liveness information gathered during the first pass.
5333 _code_cache_task.work_second_pass(worker_id);
5334
5335 // Clean all klasses that were not unloaded.
5336 _klass_cleaning_task.work();
5337 }
5338 };
5339
5340
5341 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5342 bool process_strings,
5343 bool process_symbols,
5344 bool class_unloading_occurred) {
5345 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5346 workers()->active_workers() : 1);
5347
5348 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5349 n_workers, class_unloading_occurred);
5350 if (G1CollectedHeap::use_parallel_gc_threads()) {
5351 set_par_threads(n_workers);
5352 workers()->run_task(&g1_unlink_task);
5353 set_par_threads(0);
5354 } else {
5355 g1_unlink_task.work(0);
5356 }
5357 }
5358
5359 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5360 bool process_strings, bool process_symbols) {
5361 {
5362 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5363 _g1h->workers()->active_workers() : 1);
5364 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5365 if (G1CollectedHeap::use_parallel_gc_threads()) {
5366 set_par_threads(n_workers);
5367 workers()->run_task(&g1_unlink_task);
5368 set_par_threads(0);
5369 } else {
5370 g1_unlink_task.work(0);
5371 }
5372 }
5373
5374 if (G1StringDedup::is_enabled()) {
5375 G1StringDedup::unlink(is_alive);
5376 }
5377 }
5378
5379 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5380 private:
5381 DirtyCardQueueSet* _queue;
5382 public:
5383 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5384
5385 virtual void work(uint worker_id) {
5386 double start_time = os::elapsedTime();
5387
5388 RedirtyLoggedCardTableEntryClosure cl;
5389 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5390 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5391 } else {
5392 _queue->apply_closure_to_all_completed_buffers(&cl);
5393 }
5394
5395 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5396 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5397 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5398 }
5399 };
5400
5401 void G1CollectedHeap::redirty_logged_cards() {
5402 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5403 double redirty_logged_cards_start = os::elapsedTime();
5404
5405 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5406 _g1h->workers()->active_workers() : 1);
5407
5408 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5409 dirty_card_queue_set().reset_for_par_iteration();
5410 if (use_parallel_gc_threads()) {
5411 set_par_threads(n_workers);
5412 workers()->run_task(&redirty_task);
5413 set_par_threads(0);
5414 } else {
5415 redirty_task.work(0);
5416 }
5417
5418 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5419 dcq.merge_bufferlists(&dirty_card_queue_set());
5420 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5421
5422 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5423 }
5424
5425 // Weak Reference Processing support
5426
5427 // An always "is_alive" closure that is used to preserve referents.
5428 // If the object is non-null then it's alive. Used in the preservation
5429 // of referent objects that are pointed to by reference objects
5430 // discovered by the CM ref processor.
5431 class G1AlwaysAliveClosure: public BoolObjectClosure {
5432 G1CollectedHeap* _g1;
5433 public:
5434 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5435 bool do_object_b(oop p) {
5436 if (p != NULL) {
5437 return true;
5438 }
5439 return false;
5440 }
5441 };
5442
5443 bool G1STWIsAliveClosure::do_object_b(oop p) {
5444 // An object is reachable if it is outside the collection set,
5445 // or is inside and copied.
5446 return !_g1->obj_in_cs(p) || p->is_forwarded();
5447 }
5448
5449 // Non Copying Keep Alive closure
5450 class G1KeepAliveClosure: public OopClosure {
5451 G1CollectedHeap* _g1;
5452 public:
5453 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5454 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5455 void do_oop( oop* p) {
5456 oop obj = *p;
5457
5458 if (_g1->obj_in_cs(obj)) {
5459 assert( obj->is_forwarded(), "invariant" );
5460 *p = obj->forwardee();
5461 }
5462 }
5463 };
5464
5465 // Copying Keep Alive closure - can be called from both
5466 // serial and parallel code as long as different worker
5467 // threads utilize different G1ParScanThreadState instances
5468 // and different queues.
5469
5470 class G1CopyingKeepAliveClosure: public OopClosure {
5471 G1CollectedHeap* _g1h;
5472 OopClosure* _copy_non_heap_obj_cl;
5473 G1ParScanThreadState* _par_scan_state;
5474
5475 public:
5476 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5477 OopClosure* non_heap_obj_cl,
5478 G1ParScanThreadState* pss):
5479 _g1h(g1h),
5480 _copy_non_heap_obj_cl(non_heap_obj_cl),
5481 _par_scan_state(pss)
5482 {}
5483
5484 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5485 virtual void do_oop( oop* p) { do_oop_work(p); }
5486
5487 template <class T> void do_oop_work(T* p) {
5488 oop obj = oopDesc::load_decode_heap_oop(p);
5489
5490 if (_g1h->obj_in_cs(obj)) {
5491 // If the referent object has been forwarded (either copied
5492 // to a new location or to itself in the event of an
5493 // evacuation failure) then we need to update the reference
5494 // field and, if both reference and referent are in the G1
5495 // heap, update the RSet for the referent.
5496 //
5497 // If the referent has not been forwarded then we have to keep
5498 // it alive by policy. Therefore we have copy the referent.
5499 //
5500 // If the reference field is in the G1 heap then we can push
5501 // on the PSS queue. When the queue is drained (after each
5502 // phase of reference processing) the object and it's followers
5503 // will be copied, the reference field set to point to the
5504 // new location, and the RSet updated. Otherwise we need to
5505 // use the the non-heap or metadata closures directly to copy
5506 // the referent object and update the pointer, while avoiding
5507 // updating the RSet.
5508
5509 if (_g1h->is_in_g1_reserved(p)) {
5510 _par_scan_state->push_on_queue(p);
5511 } else {
5512 assert(!Metaspace::contains((const void*)p),
5513 err_msg("Unexpectedly found a pointer from metadata: "
5514 PTR_FORMAT, p));
5515 _copy_non_heap_obj_cl->do_oop(p);
5516 }
5517 }
5518 }
5519 };
5520
5521 // Serial drain queue closure. Called as the 'complete_gc'
5522 // closure for each discovered list in some of the
5523 // reference processing phases.
5524
5525 class G1STWDrainQueueClosure: public VoidClosure {
5526 protected:
5527 G1CollectedHeap* _g1h;
5528 G1ParScanThreadState* _par_scan_state;
5529
5530 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5531
5532 public:
5533 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5534 _g1h(g1h),
5535 _par_scan_state(pss)
5536 { }
5537
5538 void do_void() {
5539 G1ParScanThreadState* const pss = par_scan_state();
5540 pss->trim_queue();
5541 }
5542 };
5543
5544 // Parallel Reference Processing closures
5545
5546 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5547 // processing during G1 evacuation pauses.
5548
5549 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5550 private:
5551 G1CollectedHeap* _g1h;
5552 RefToScanQueueSet* _queues;
5553 FlexibleWorkGang* _workers;
5554 int _active_workers;
5555
5556 public:
5557 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5558 FlexibleWorkGang* workers,
5559 RefToScanQueueSet *task_queues,
5560 int n_workers) :
5561 _g1h(g1h),
5562 _queues(task_queues),
5563 _workers(workers),
5564 _active_workers(n_workers)
5565 {
5566 assert(n_workers > 0, "shouldn't call this otherwise");
5567 }
5568
5569 // Executes the given task using concurrent marking worker threads.
5570 virtual void execute(ProcessTask& task);
5571 virtual void execute(EnqueueTask& task);
5572 };
5573
5574 // Gang task for possibly parallel reference processing
5575
5576 class G1STWRefProcTaskProxy: public AbstractGangTask {
5577 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5578 ProcessTask& _proc_task;
5579 G1CollectedHeap* _g1h;
5580 RefToScanQueueSet *_task_queues;
5581 ParallelTaskTerminator* _terminator;
5582
5583 public:
5584 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5585 G1CollectedHeap* g1h,
5586 RefToScanQueueSet *task_queues,
5587 ParallelTaskTerminator* terminator) :
5588 AbstractGangTask("Process reference objects in parallel"),
5589 _proc_task(proc_task),
5590 _g1h(g1h),
5591 _task_queues(task_queues),
5592 _terminator(terminator)
5593 {}
5594
5595 virtual void work(uint worker_id) {
5596 // The reference processing task executed by a single worker.
5597 ResourceMark rm;
5598 HandleMark hm;
5599
5600 G1STWIsAliveClosure is_alive(_g1h);
5601
5602 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5603 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5604
5605 pss.set_evac_failure_closure(&evac_failure_cl);
5606
5607 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5608
5609 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5610
5611 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5612
5613 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5614 // We also need to mark copied objects.
5615 copy_non_heap_cl = ©_mark_non_heap_cl;
5616 }
5617
5618 // Keep alive closure.
5619 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5620
5621 // Complete GC closure
5622 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5623
5624 // Call the reference processing task's work routine.
5625 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5626
5627 // Note we cannot assert that the refs array is empty here as not all
5628 // of the processing tasks (specifically phase2 - pp2_work) execute
5629 // the complete_gc closure (which ordinarily would drain the queue) so
5630 // the queue may not be empty.
5631 }
5632 };
5633
5634 // Driver routine for parallel reference processing.
5635 // Creates an instance of the ref processing gang
5636 // task and has the worker threads execute it.
5637 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5638 assert(_workers != NULL, "Need parallel worker threads.");
5639
5640 ParallelTaskTerminator terminator(_active_workers, _queues);
5641 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5642
5643 _g1h->set_par_threads(_active_workers);
5644 _workers->run_task(&proc_task_proxy);
5645 _g1h->set_par_threads(0);
5646 }
5647
5648 // Gang task for parallel reference enqueueing.
5649
5650 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5651 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5652 EnqueueTask& _enq_task;
5653
5654 public:
5655 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5656 AbstractGangTask("Enqueue reference objects in parallel"),
5657 _enq_task(enq_task)
5658 { }
5659
5660 virtual void work(uint worker_id) {
5661 _enq_task.work(worker_id);
5662 }
5663 };
5664
5665 // Driver routine for parallel reference enqueueing.
5666 // Creates an instance of the ref enqueueing gang
5667 // task and has the worker threads execute it.
5668
5669 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5670 assert(_workers != NULL, "Need parallel worker threads.");
5671
5672 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5673
5674 _g1h->set_par_threads(_active_workers);
5675 _workers->run_task(&enq_task_proxy);
5676 _g1h->set_par_threads(0);
5677 }
5678
5679 // End of weak reference support closures
5680
5681 // Abstract task used to preserve (i.e. copy) any referent objects
5682 // that are in the collection set and are pointed to by reference
5683 // objects discovered by the CM ref processor.
5684
5685 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5686 protected:
5687 G1CollectedHeap* _g1h;
5688 RefToScanQueueSet *_queues;
5689 ParallelTaskTerminator _terminator;
5690 uint _n_workers;
5691
5692 public:
5693 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5694 AbstractGangTask("ParPreserveCMReferents"),
5695 _g1h(g1h),
5696 _queues(task_queues),
5697 _terminator(workers, _queues),
5698 _n_workers(workers)
5699 { }
5700
5701 void work(uint worker_id) {
5702 ResourceMark rm;
5703 HandleMark hm;
5704
5705 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5706 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5707
5708 pss.set_evac_failure_closure(&evac_failure_cl);
5709
5710 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5711
5712 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5713
5714 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5715
5716 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5717
5718 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5719 // We also need to mark copied objects.
5720 copy_non_heap_cl = ©_mark_non_heap_cl;
5721 }
5722
5723 // Is alive closure
5724 G1AlwaysAliveClosure always_alive(_g1h);
5725
5726 // Copying keep alive closure. Applied to referent objects that need
5727 // to be copied.
5728 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5729
5730 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5731
5732 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5733 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5734
5735 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5736 // So this must be true - but assert just in case someone decides to
5737 // change the worker ids.
5738 assert(0 <= worker_id && worker_id < limit, "sanity");
5739 assert(!rp->discovery_is_atomic(), "check this code");
5740
5741 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5742 for (uint idx = worker_id; idx < limit; idx += stride) {
5743 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5744
5745 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5746 while (iter.has_next()) {
5747 // Since discovery is not atomic for the CM ref processor, we
5748 // can see some null referent objects.
5749 iter.load_ptrs(DEBUG_ONLY(true));
5750 oop ref = iter.obj();
5751
5752 // This will filter nulls.
5753 if (iter.is_referent_alive()) {
5754 iter.make_referent_alive();
5755 }
5756 iter.move_to_next();
5757 }
5758 }
5759
5760 // Drain the queue - which may cause stealing
5761 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5762 drain_queue.do_void();
5763 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5764 assert(pss.queue_is_empty(), "should be");
5765 }
5766 };
5767
5768 // Weak Reference processing during an evacuation pause (part 1).
5769 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5770 double ref_proc_start = os::elapsedTime();
5771
5772 ReferenceProcessor* rp = _ref_processor_stw;
5773 assert(rp->discovery_enabled(), "should have been enabled");
5774
5775 // Any reference objects, in the collection set, that were 'discovered'
5776 // by the CM ref processor should have already been copied (either by
5777 // applying the external root copy closure to the discovered lists, or
5778 // by following an RSet entry).
5779 //
5780 // But some of the referents, that are in the collection set, that these
5781 // reference objects point to may not have been copied: the STW ref
5782 // processor would have seen that the reference object had already
5783 // been 'discovered' and would have skipped discovering the reference,
5784 // but would not have treated the reference object as a regular oop.
5785 // As a result the copy closure would not have been applied to the
5786 // referent object.
5787 //
5788 // We need to explicitly copy these referent objects - the references
5789 // will be processed at the end of remarking.
5790 //
5791 // We also need to do this copying before we process the reference
5792 // objects discovered by the STW ref processor in case one of these
5793 // referents points to another object which is also referenced by an
5794 // object discovered by the STW ref processor.
5795
5796 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5797 no_of_gc_workers == workers()->active_workers(),
5798 "Need to reset active GC workers");
5799
5800 set_par_threads(no_of_gc_workers);
5801 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5802 no_of_gc_workers,
5803 _task_queues);
5804
5805 if (G1CollectedHeap::use_parallel_gc_threads()) {
5806 workers()->run_task(&keep_cm_referents);
5807 } else {
5808 keep_cm_referents.work(0);
5809 }
5810
5811 set_par_threads(0);
5812
5813 // Closure to test whether a referent is alive.
5814 G1STWIsAliveClosure is_alive(this);
5815
5816 // Even when parallel reference processing is enabled, the processing
5817 // of JNI refs is serial and performed serially by the current thread
5818 // rather than by a worker. The following PSS will be used for processing
5819 // JNI refs.
5820
5821 // Use only a single queue for this PSS.
5822 G1ParScanThreadState pss(this, 0, NULL);
5823
5824 // We do not embed a reference processor in the copying/scanning
5825 // closures while we're actually processing the discovered
5826 // reference objects.
5827 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5828
5829 pss.set_evac_failure_closure(&evac_failure_cl);
5830
5831 assert(pss.queue_is_empty(), "pre-condition");
5832
5833 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5834
5835 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5836
5837 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5838
5839 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5840 // We also need to mark copied objects.
5841 copy_non_heap_cl = ©_mark_non_heap_cl;
5842 }
5843
5844 // Keep alive closure.
5845 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5846
5847 // Serial Complete GC closure
5848 G1STWDrainQueueClosure drain_queue(this, &pss);
5849
5850 // Setup the soft refs policy...
5851 rp->setup_policy(false);
5852
5853 ReferenceProcessorStats stats;
5854 if (!rp->processing_is_mt()) {
5855 // Serial reference processing...
5856 stats = rp->process_discovered_references(&is_alive,
5857 &keep_alive,
5858 &drain_queue,
5859 NULL,
5860 _gc_timer_stw,
5861 _gc_tracer_stw->gc_id());
5862 } else {
5863 // Parallel reference processing
5864 assert(rp->num_q() == no_of_gc_workers, "sanity");
5865 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5866
5867 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5868 stats = rp->process_discovered_references(&is_alive,
5869 &keep_alive,
5870 &drain_queue,
5871 &par_task_executor,
5872 _gc_timer_stw,
5873 _gc_tracer_stw->gc_id());
5874 }
5875
5876 _gc_tracer_stw->report_gc_reference_stats(stats);
5877
5878 // We have completed copying any necessary live referent objects.
5879 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5880
5881 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5882 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5883 }
5884
5885 // Weak Reference processing during an evacuation pause (part 2).
5886 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5887 double ref_enq_start = os::elapsedTime();
5888
5889 ReferenceProcessor* rp = _ref_processor_stw;
5890 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5891
5892 // Now enqueue any remaining on the discovered lists on to
5893 // the pending list.
5894 if (!rp->processing_is_mt()) {
5895 // Serial reference processing...
5896 rp->enqueue_discovered_references();
5897 } else {
5898 // Parallel reference enqueueing
5899
5900 assert(no_of_gc_workers == workers()->active_workers(),
5901 "Need to reset active workers");
5902 assert(rp->num_q() == no_of_gc_workers, "sanity");
5903 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5904
5905 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5906 rp->enqueue_discovered_references(&par_task_executor);
5907 }
5908
5909 rp->verify_no_references_recorded();
5910 assert(!rp->discovery_enabled(), "should have been disabled");
5911
5912 // FIXME
5913 // CM's reference processing also cleans up the string and symbol tables.
5914 // Should we do that here also? We could, but it is a serial operation
5915 // and could significantly increase the pause time.
5916
5917 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5918 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5919 }
5920
5921 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5922 _expand_heap_after_alloc_failure = true;
5923 _evacuation_failed = false;
5924
5925 // Should G1EvacuationFailureALot be in effect for this GC?
5926 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5927
5928 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5929
5930 // Disable the hot card cache.
5931 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5932 hot_card_cache->reset_hot_cache_claimed_index();
5933 hot_card_cache->set_use_cache(false);
5934
5935 uint n_workers;
5936 if (G1CollectedHeap::use_parallel_gc_threads()) {
5937 n_workers =
5938 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5939 workers()->active_workers(),
5940 Threads::number_of_non_daemon_threads());
5941 assert(UseDynamicNumberOfGCThreads ||
5942 n_workers == workers()->total_workers(),
5943 "If not dynamic should be using all the workers");
5944 workers()->set_active_workers(n_workers);
5945 set_par_threads(n_workers);
5946 } else {
5947 assert(n_par_threads() == 0,
5948 "Should be the original non-parallel value");
5949 n_workers = 1;
5950 }
5951
5952 G1ParTask g1_par_task(this, _task_queues);
5953
5954 init_for_evac_failure(NULL);
5955
5956 rem_set()->prepare_for_younger_refs_iterate(true);
5957
5958 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5959 double start_par_time_sec = os::elapsedTime();
5960 double end_par_time_sec;
5961
5962 {
5963 StrongRootsScope srs(this);
5964 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5965 if (g1_policy()->during_initial_mark_pause()) {
5966 ClassLoaderDataGraph::clear_claimed_marks();
5967 }
5968
5969 if (G1CollectedHeap::use_parallel_gc_threads()) {
5970 // The individual threads will set their evac-failure closures.
5971 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5972 // These tasks use ShareHeap::_process_strong_tasks
5973 assert(UseDynamicNumberOfGCThreads ||
5974 workers()->active_workers() == workers()->total_workers(),
5975 "If not dynamic should be using all the workers");
5976 workers()->run_task(&g1_par_task);
5977 } else {
5978 g1_par_task.set_for_termination(n_workers);
5979 g1_par_task.work(0);
5980 }
5981 end_par_time_sec = os::elapsedTime();
5982
5983 // Closing the inner scope will execute the destructor
5984 // for the StrongRootsScope object. We record the current
5985 // elapsed time before closing the scope so that time
5986 // taken for the SRS destructor is NOT included in the
5987 // reported parallel time.
5988 }
5989
5990 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5991 g1_policy()->phase_times()->record_par_time(par_time_ms);
5992
5993 double code_root_fixup_time_ms =
5994 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5995 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5996
5997 set_par_threads(0);
5998
5999 // Process any discovered reference objects - we have
6000 // to do this _before_ we retire the GC alloc regions
6001 // as we may have to copy some 'reachable' referent
6002 // objects (and their reachable sub-graphs) that were
6003 // not copied during the pause.
6004 process_discovered_references(n_workers);
6005
6006 // Weak root processing.
6007 {
6008 G1STWIsAliveClosure is_alive(this);
6009 G1KeepAliveClosure keep_alive(this);
6010 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
6011 if (G1StringDedup::is_enabled()) {
6012 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
6013 }
6014 }
6015
6016 release_gc_alloc_regions(n_workers, evacuation_info);
6017 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
6018
6019 // Reset and re-enable the hot card cache.
6020 // Note the counts for the cards in the regions in the
6021 // collection set are reset when the collection set is freed.
6022 hot_card_cache->reset_hot_cache();
6023 hot_card_cache->set_use_cache(true);
6024
6025 // Migrate the strong code roots attached to each region in
6026 // the collection set. Ideally we would like to do this
6027 // after we have finished the scanning/evacuation of the
6028 // strong code roots for a particular heap region.
6029 migrate_strong_code_roots();
6030
6031 purge_code_root_memory();
6032
6033 if (g1_policy()->during_initial_mark_pause()) {
6034 // Reset the claim values set during marking the strong code roots
6035 reset_heap_region_claim_values();
6036 }
6037
6038 finalize_for_evac_failure();
6039
6040 if (evacuation_failed()) {
6041 remove_self_forwarding_pointers();
6042
6043 // Reset the G1EvacuationFailureALot counters and flags
6044 // Note: the values are reset only when an actual
6045 // evacuation failure occurs.
6046 NOT_PRODUCT(reset_evacuation_should_fail();)
6047 }
6048
6049 // Enqueue any remaining references remaining on the STW
6050 // reference processor's discovered lists. We need to do
6051 // this after the card table is cleaned (and verified) as
6052 // the act of enqueueing entries on to the pending list
6053 // will log these updates (and dirty their associated
6054 // cards). We need these updates logged to update any
6055 // RSets.
6056 enqueue_discovered_references(n_workers);
6057
6058 if (G1DeferredRSUpdate) {
6059 redirty_logged_cards();
6060 }
6061 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
6062 }
6063
6064 void G1CollectedHeap::free_region(HeapRegion* hr,
6065 FreeRegionList* free_list,
6066 bool par,
6067 bool locked) {
6068 assert(!hr->isHumongous(), "this is only for non-humongous regions");
6069 assert(!hr->is_empty(), "the region should not be empty");
6070 assert(free_list != NULL, "pre-condition");
6071
6072 if (G1VerifyBitmaps) {
6073 MemRegion mr(hr->bottom(), hr->end());
6074 concurrent_mark()->clearRangePrevBitmap(mr);
6075 }
6076
6077 // Clear the card counts for this region.
6078 // Note: we only need to do this if the region is not young
6079 // (since we don't refine cards in young regions).
6080 if (!hr->is_young()) {
6081 _cg1r->hot_card_cache()->reset_card_counts(hr);
6082 }
6083 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
6084 free_list->add_ordered(hr);
6085 }
6086
6087 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
6088 FreeRegionList* free_list,
6089 bool par) {
6090 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6091 assert(free_list != NULL, "pre-condition");
6092
6093 size_t hr_capacity = hr->capacity();
6094 // We need to read this before we make the region non-humongous,
6095 // otherwise the information will be gone.
6096 uint last_index = hr->last_hc_index();
6097 hr->set_notHumongous();
6098 free_region(hr, free_list, par);
6099
6100 uint i = hr->hrs_index() + 1;
6101 while (i < last_index) {
6102 HeapRegion* curr_hr = region_at(i);
6103 assert(curr_hr->continuesHumongous(), "invariant");
6104 curr_hr->set_notHumongous();
6105 free_region(curr_hr, free_list, par);
6106 i += 1;
6107 }
6108 }
6109
6110 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6111 const HeapRegionSetCount& humongous_regions_removed) {
6112 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6113 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6114 _old_set.bulk_remove(old_regions_removed);
6115 _humongous_set.bulk_remove(humongous_regions_removed);
6116 }
6117
6118 }
6119
6120 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6121 assert(list != NULL, "list can't be null");
6122 if (!list->is_empty()) {
6123 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6124 _free_list.add_ordered(list);
6125 }
6126 }
6127
6128 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6129 assert(_summary_bytes_used >= bytes,
6130 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6131 _summary_bytes_used, bytes));
6132 _summary_bytes_used -= bytes;
6133 }
6134
6135 class G1ParCleanupCTTask : public AbstractGangTask {
6136 G1SATBCardTableModRefBS* _ct_bs;
6137 G1CollectedHeap* _g1h;
6138 HeapRegion* volatile _su_head;
6139 public:
6140 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6141 G1CollectedHeap* g1h) :
6142 AbstractGangTask("G1 Par Cleanup CT Task"),
6143 _ct_bs(ct_bs), _g1h(g1h) { }
6144
6145 void work(uint worker_id) {
6146 HeapRegion* r;
6147 while (r = _g1h->pop_dirty_cards_region()) {
6148 clear_cards(r);
6149 }
6150 }
6151
6152 void clear_cards(HeapRegion* r) {
6153 // Cards of the survivors should have already been dirtied.
6154 if (!r->is_survivor()) {
6155 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6156 }
6157 }
6158 };
6159
6160 #ifndef PRODUCT
6161 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6162 G1CollectedHeap* _g1h;
6163 G1SATBCardTableModRefBS* _ct_bs;
6164 public:
6165 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6166 : _g1h(g1h), _ct_bs(ct_bs) { }
6167 virtual bool doHeapRegion(HeapRegion* r) {
6168 if (r->is_survivor()) {
6169 _g1h->verify_dirty_region(r);
6170 } else {
6171 _g1h->verify_not_dirty_region(r);
6172 }
6173 return false;
6174 }
6175 };
6176
6177 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6178 // All of the region should be clean.
6179 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6180 MemRegion mr(hr->bottom(), hr->end());
6181 ct_bs->verify_not_dirty_region(mr);
6182 }
6183
6184 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6185 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6186 // dirty allocated blocks as they allocate them. The thread that
6187 // retires each region and replaces it with a new one will do a
6188 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6189 // not dirty that area (one less thing to have to do while holding
6190 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6191 // is dirty.
6192 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6193 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6194 if (hr->is_young()) {
6195 ct_bs->verify_g1_young_region(mr);
6196 } else {
6197 ct_bs->verify_dirty_region(mr);
6198 }
6199 }
6200
6201 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6202 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6203 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6204 verify_dirty_region(hr);
6205 }
6206 }
6207
6208 void G1CollectedHeap::verify_dirty_young_regions() {
6209 verify_dirty_young_list(_young_list->first_region());
6210 }
6211
6212 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6213 HeapWord* tams, HeapWord* end) {
6214 guarantee(tams <= end,
6215 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6216 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6217 if (result < end) {
6218 gclog_or_tty->cr();
6219 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6220 bitmap_name, result);
6221 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6222 bitmap_name, tams, end);
6223 return false;
6224 }
6225 return true;
6226 }
6227
6228 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6229 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6230 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6231
6232 HeapWord* bottom = hr->bottom();
6233 HeapWord* ptams = hr->prev_top_at_mark_start();
6234 HeapWord* ntams = hr->next_top_at_mark_start();
6235 HeapWord* end = hr->end();
6236
6237 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6238
6239 bool res_n = true;
6240 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6241 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6242 // if we happen to be in that state.
6243 if (mark_in_progress() || !_cmThread->in_progress()) {
6244 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6245 }
6246 if (!res_p || !res_n) {
6247 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6248 HR_FORMAT_PARAMS(hr));
6249 gclog_or_tty->print_cr("#### Caller: %s", caller);
6250 return false;
6251 }
6252 return true;
6253 }
6254
6255 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6256 if (!G1VerifyBitmaps) return;
6257
6258 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6259 }
6260
6261 class G1VerifyBitmapClosure : public HeapRegionClosure {
6262 private:
6263 const char* _caller;
6264 G1CollectedHeap* _g1h;
6265 bool _failures;
6266
6267 public:
6268 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6269 _caller(caller), _g1h(g1h), _failures(false) { }
6270
6271 bool failures() { return _failures; }
6272
6273 virtual bool doHeapRegion(HeapRegion* hr) {
6274 if (hr->continuesHumongous()) return false;
6275
6276 bool result = _g1h->verify_bitmaps(_caller, hr);
6277 if (!result) {
6278 _failures = true;
6279 }
6280 return false;
6281 }
6282 };
6283
6284 void G1CollectedHeap::check_bitmaps(const char* caller) {
6285 if (!G1VerifyBitmaps) return;
6286
6287 G1VerifyBitmapClosure cl(caller, this);
6288 heap_region_iterate(&cl);
6289 guarantee(!cl.failures(), "bitmap verification");
6290 }
6291 #endif // PRODUCT
6292
6293 void G1CollectedHeap::cleanUpCardTable() {
6294 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6295 double start = os::elapsedTime();
6296
6297 {
6298 // Iterate over the dirty cards region list.
6299 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6300
6301 if (G1CollectedHeap::use_parallel_gc_threads()) {
6302 set_par_threads();
6303 workers()->run_task(&cleanup_task);
6304 set_par_threads(0);
6305 } else {
6306 while (_dirty_cards_region_list) {
6307 HeapRegion* r = _dirty_cards_region_list;
6308 cleanup_task.clear_cards(r);
6309 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6310 if (_dirty_cards_region_list == r) {
6311 // The last region.
6312 _dirty_cards_region_list = NULL;
6313 }
6314 r->set_next_dirty_cards_region(NULL);
6315 }
6316 }
6317 #ifndef PRODUCT
6318 if (G1VerifyCTCleanup || VerifyAfterGC) {
6319 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6320 heap_region_iterate(&cleanup_verifier);
6321 }
6322 #endif
6323 }
6324
6325 double elapsed = os::elapsedTime() - start;
6326 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6327 }
6328
6329 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6330 size_t pre_used = 0;
6331 FreeRegionList local_free_list("Local List for CSet Freeing");
6332
6333 double young_time_ms = 0.0;
6334 double non_young_time_ms = 0.0;
6335
6336 // Since the collection set is a superset of the the young list,
6337 // all we need to do to clear the young list is clear its
6338 // head and length, and unlink any young regions in the code below
6339 _young_list->clear();
6340
6341 G1CollectorPolicy* policy = g1_policy();
6342
6343 double start_sec = os::elapsedTime();
6344 bool non_young = true;
6345
6346 HeapRegion* cur = cs_head;
6347 int age_bound = -1;
6348 size_t rs_lengths = 0;
6349
6350 while (cur != NULL) {
6351 assert(!is_on_master_free_list(cur), "sanity");
6352 if (non_young) {
6353 if (cur->is_young()) {
6354 double end_sec = os::elapsedTime();
6355 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6356 non_young_time_ms += elapsed_ms;
6357
6358 start_sec = os::elapsedTime();
6359 non_young = false;
6360 }
6361 } else {
6362 if (!cur->is_young()) {
6363 double end_sec = os::elapsedTime();
6364 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6365 young_time_ms += elapsed_ms;
6366
6367 start_sec = os::elapsedTime();
6368 non_young = true;
6369 }
6370 }
6371
6372 rs_lengths += cur->rem_set()->occupied_locked();
6373
6374 HeapRegion* next = cur->next_in_collection_set();
6375 assert(cur->in_collection_set(), "bad CS");
6376 cur->set_next_in_collection_set(NULL);
6377 cur->set_in_collection_set(false);
6378
6379 if (cur->is_young()) {
6380 int index = cur->young_index_in_cset();
6381 assert(index != -1, "invariant");
6382 assert((uint) index < policy->young_cset_region_length(), "invariant");
6383 size_t words_survived = _surviving_young_words[index];
6384 cur->record_surv_words_in_group(words_survived);
6385
6386 // At this point the we have 'popped' cur from the collection set
6387 // (linked via next_in_collection_set()) but it is still in the
6388 // young list (linked via next_young_region()). Clear the
6389 // _next_young_region field.
6390 cur->set_next_young_region(NULL);
6391 } else {
6392 int index = cur->young_index_in_cset();
6393 assert(index == -1, "invariant");
6394 }
6395
6396 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6397 (!cur->is_young() && cur->young_index_in_cset() == -1),
6398 "invariant" );
6399
6400 if (!cur->evacuation_failed()) {
6401 MemRegion used_mr = cur->used_region();
6402
6403 // And the region is empty.
6404 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6405 pre_used += cur->used();
6406 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6407 } else {
6408 cur->uninstall_surv_rate_group();
6409 if (cur->is_young()) {
6410 cur->set_young_index_in_cset(-1);
6411 }
6412 cur->set_not_young();
6413 cur->set_evacuation_failed(false);
6414 // The region is now considered to be old.
6415 _old_set.add(cur);
6416 evacuation_info.increment_collectionset_used_after(cur->used());
6417 }
6418 cur = next;
6419 }
6420
6421 evacuation_info.set_regions_freed(local_free_list.length());
6422 policy->record_max_rs_lengths(rs_lengths);
6423 policy->cset_regions_freed();
6424
6425 double end_sec = os::elapsedTime();
6426 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6427
6428 if (non_young) {
6429 non_young_time_ms += elapsed_ms;
6430 } else {
6431 young_time_ms += elapsed_ms;
6432 }
6433
6434 prepend_to_freelist(&local_free_list);
6435 decrement_summary_bytes(pre_used);
6436 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6437 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6438 }
6439
6440 // This routine is similar to the above but does not record
6441 // any policy statistics or update free lists; we are abandoning
6442 // the current incremental collection set in preparation of a
6443 // full collection. After the full GC we will start to build up
6444 // the incremental collection set again.
6445 // This is only called when we're doing a full collection
6446 // and is immediately followed by the tearing down of the young list.
6447
6448 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6449 HeapRegion* cur = cs_head;
6450
6451 while (cur != NULL) {
6452 HeapRegion* next = cur->next_in_collection_set();
6453 assert(cur->in_collection_set(), "bad CS");
6454 cur->set_next_in_collection_set(NULL);
6455 cur->set_in_collection_set(false);
6456 cur->set_young_index_in_cset(-1);
6457 cur = next;
6458 }
6459 }
6460
6461 void G1CollectedHeap::set_free_regions_coming() {
6462 if (G1ConcRegionFreeingVerbose) {
6463 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6464 "setting free regions coming");
6465 }
6466
6467 assert(!free_regions_coming(), "pre-condition");
6468 _free_regions_coming = true;
6469 }
6470
6471 void G1CollectedHeap::reset_free_regions_coming() {
6472 assert(free_regions_coming(), "pre-condition");
6473
6474 {
6475 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6476 _free_regions_coming = false;
6477 SecondaryFreeList_lock->notify_all();
6478 }
6479
6480 if (G1ConcRegionFreeingVerbose) {
6481 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6482 "reset free regions coming");
6483 }
6484 }
6485
6486 void G1CollectedHeap::wait_while_free_regions_coming() {
6487 // Most of the time we won't have to wait, so let's do a quick test
6488 // first before we take the lock.
6489 if (!free_regions_coming()) {
6490 return;
6491 }
6492
6493 if (G1ConcRegionFreeingVerbose) {
6494 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6495 "waiting for free regions");
6496 }
6497
6498 {
6499 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6500 while (free_regions_coming()) {
6501 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6502 }
6503 }
6504
6505 if (G1ConcRegionFreeingVerbose) {
6506 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6507 "done waiting for free regions");
6508 }
6509 }
6510
6511 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6512 assert(heap_lock_held_for_gc(),
6513 "the heap lock should already be held by or for this thread");
6514 _young_list->push_region(hr);
6515 }
6516
6517 class NoYoungRegionsClosure: public HeapRegionClosure {
6518 private:
6519 bool _success;
6520 public:
6521 NoYoungRegionsClosure() : _success(true) { }
6522 bool doHeapRegion(HeapRegion* r) {
6523 if (r->is_young()) {
6524 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6525 r->bottom(), r->end());
6526 _success = false;
6527 }
6528 return false;
6529 }
6530 bool success() { return _success; }
6531 };
6532
6533 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6534 bool ret = _young_list->check_list_empty(check_sample);
6535
6536 if (check_heap) {
6537 NoYoungRegionsClosure closure;
6538 heap_region_iterate(&closure);
6539 ret = ret && closure.success();
6540 }
6541
6542 return ret;
6543 }
6544
6545 class TearDownRegionSetsClosure : public HeapRegionClosure {
6546 private:
6547 HeapRegionSet *_old_set;
6548
6549 public:
6550 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6551
6552 bool doHeapRegion(HeapRegion* r) {
6553 if (r->is_empty()) {
6554 // We ignore empty regions, we'll empty the free list afterwards
6555 } else if (r->is_young()) {
6556 // We ignore young regions, we'll empty the young list afterwards
6557 } else if (r->isHumongous()) {
6558 // We ignore humongous regions, we're not tearing down the
6559 // humongous region set
6560 } else {
6561 // The rest should be old
6562 _old_set->remove(r);
6563 }
6564 return false;
6565 }
6566
6567 ~TearDownRegionSetsClosure() {
6568 assert(_old_set->is_empty(), "post-condition");
6569 }
6570 };
6571
6572 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6573 assert_at_safepoint(true /* should_be_vm_thread */);
6574
6575 if (!free_list_only) {
6576 TearDownRegionSetsClosure cl(&_old_set);
6577 heap_region_iterate(&cl);
6578
6579 // Note that emptying the _young_list is postponed and instead done as
6580 // the first step when rebuilding the regions sets again. The reason for
6581 // this is that during a full GC string deduplication needs to know if
6582 // a collected region was young or old when the full GC was initiated.
6583 }
6584 _free_list.remove_all();
6585 }
6586
6587 class RebuildRegionSetsClosure : public HeapRegionClosure {
6588 private:
6589 bool _free_list_only;
6590 HeapRegionSet* _old_set;
6591 FreeRegionList* _free_list;
6592 size_t _total_used;
6593
6594 public:
6595 RebuildRegionSetsClosure(bool free_list_only,
6596 HeapRegionSet* old_set, FreeRegionList* free_list) :
6597 _free_list_only(free_list_only),
6598 _old_set(old_set), _free_list(free_list), _total_used(0) {
6599 assert(_free_list->is_empty(), "pre-condition");
6600 if (!free_list_only) {
6601 assert(_old_set->is_empty(), "pre-condition");
6602 }
6603 }
6604
6605 bool doHeapRegion(HeapRegion* r) {
6606 if (r->continuesHumongous()) {
6607 return false;
6608 }
6609
6610 if (r->is_empty()) {
6611 // Add free regions to the free list
6612 _free_list->add_as_tail(r);
6613 } else if (!_free_list_only) {
6614 assert(!r->is_young(), "we should not come across young regions");
6615
6616 if (r->startsHumongous()) {
6617 // We ignore humongous regions, we left the humongous set unchanged
6618 } else if (r->continuesHumongous()) {
6619 } else {
6620 // The rest should be old, add them to the old set
6621 _old_set->add(r);
6622 }
6623 _total_used += r->used();
6624 }
6625
6626 return false;
6627 }
6628
6629 size_t total_used() {
6630 return _total_used;
6631 }
6632 };
6633
6634 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6635 assert_at_safepoint(true /* should_be_vm_thread */);
6636
6637 if (!free_list_only) {
6638 _young_list->empty_list();
6639 }
6640
6641 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6642 heap_region_iterate(&cl);
6643
6644 if (!free_list_only) {
6645 _summary_bytes_used = cl.total_used();
6646 }
6647 assert(_summary_bytes_used == recalculate_used(),
6648 err_msg("inconsistent _summary_bytes_used, "
6649 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6650 _summary_bytes_used, recalculate_used()));
6651 }
6652
6653 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6654 _refine_cte_cl->set_concurrent(concurrent);
6655 }
6656
6657 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6658 HeapRegion* hr = heap_region_containing(p);
6659 return hr->is_in(p);
6660 }
6661
6662 // Methods for the mutator alloc region
6663
6664 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6665 bool force) {
6666 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6667 assert(!force || g1_policy()->can_expand_young_list(),
6668 "if force is true we should be able to expand the young list");
6669 bool young_list_full = g1_policy()->is_young_list_full();
6670 if (force || !young_list_full) {
6671 HeapRegion* new_alloc_region = new_region(word_size,
6672 false /* is_old */,
6673 false /* do_expand */);
6674 if (new_alloc_region != NULL) {
6675 set_region_short_lived_locked(new_alloc_region);
6676 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6677 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6678 return new_alloc_region;
6679 }
6680 }
6681 return NULL;
6682 }
6683
6684 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6685 size_t allocated_bytes) {
6686 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6687 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6688
6689 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6690 _summary_bytes_used += allocated_bytes;
6691 _hr_printer.retire(alloc_region);
6692 // We update the eden sizes here, when the region is retired,
6693 // instead of when it's allocated, since this is the point that its
6694 // used space has been recored in _summary_bytes_used.
6695 g1mm()->update_eden_size();
6696 }
6697
6698 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6699 bool force) {
6700 return _g1h->new_mutator_alloc_region(word_size, force);
6701 }
6702
6703 void G1CollectedHeap::set_par_threads() {
6704 // Don't change the number of workers. Use the value previously set
6705 // in the workgroup.
6706 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6707 uint n_workers = workers()->active_workers();
6708 assert(UseDynamicNumberOfGCThreads ||
6709 n_workers == workers()->total_workers(),
6710 "Otherwise should be using the total number of workers");
6711 if (n_workers == 0) {
6712 assert(false, "Should have been set in prior evacuation pause.");
6713 n_workers = ParallelGCThreads;
6714 workers()->set_active_workers(n_workers);
6715 }
6716 set_par_threads(n_workers);
6717 }
6718
6719 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6720 size_t allocated_bytes) {
6721 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6722 }
6723
6724 // Methods for the GC alloc regions
6725
6726 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6727 uint count,
6728 GCAllocPurpose ap) {
6729 assert(FreeList_lock->owned_by_self(), "pre-condition");
6730
6731 if (count < g1_policy()->max_regions(ap)) {
6732 bool survivor = (ap == GCAllocForSurvived);
6733 HeapRegion* new_alloc_region = new_region(word_size,
6734 !survivor,
6735 true /* do_expand */);
6736 if (new_alloc_region != NULL) {
6737 // We really only need to do this for old regions given that we
6738 // should never scan survivors. But it doesn't hurt to do it
6739 // for survivors too.
6740 new_alloc_region->record_top_and_timestamp();
6741 if (survivor) {
6742 new_alloc_region->set_survivor();
6743 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6744 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6745 } else {
6746 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6747 check_bitmaps("Old Region Allocation", new_alloc_region);
6748 }
6749 bool during_im = g1_policy()->during_initial_mark_pause();
6750 new_alloc_region->note_start_of_copying(during_im);
6751 return new_alloc_region;
6752 } else {
6753 g1_policy()->note_alloc_region_limit_reached(ap);
6754 }
6755 }
6756 return NULL;
6757 }
6758
6759 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6760 size_t allocated_bytes,
6761 GCAllocPurpose ap) {
6762 bool during_im = g1_policy()->during_initial_mark_pause();
6763 alloc_region->note_end_of_copying(during_im);
6764 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6765 if (ap == GCAllocForSurvived) {
6766 young_list()->add_survivor_region(alloc_region);
6767 } else {
6768 _old_set.add(alloc_region);
6769 }
6770 _hr_printer.retire(alloc_region);
6771 }
6772
6773 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6774 bool force) {
6775 assert(!force, "not supported for GC alloc regions");
6776 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6777 }
6778
6779 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6780 size_t allocated_bytes) {
6781 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6782 GCAllocForSurvived);
6783 }
6784
6785 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6786 bool force) {
6787 assert(!force, "not supported for GC alloc regions");
6788 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6789 }
6790
6791 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6792 size_t allocated_bytes) {
6793 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6794 GCAllocForTenured);
6795 }
6796 // Heap region set verification
6797
6798 class VerifyRegionListsClosure : public HeapRegionClosure {
6799 private:
6800 HeapRegionSet* _old_set;
6801 HeapRegionSet* _humongous_set;
6802 FreeRegionList* _free_list;
6803
6804 public:
6805 HeapRegionSetCount _old_count;
6806 HeapRegionSetCount _humongous_count;
6807 HeapRegionSetCount _free_count;
6808
6809 VerifyRegionListsClosure(HeapRegionSet* old_set,
6810 HeapRegionSet* humongous_set,
6811 FreeRegionList* free_list) :
6812 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6813 _old_count(), _humongous_count(), _free_count(){ }
6814
6815 bool doHeapRegion(HeapRegion* hr) {
6816 if (hr->continuesHumongous()) {
6817 return false;
6818 }
6819
6820 if (hr->is_young()) {
6821 // TODO
6822 } else if (hr->startsHumongous()) {
6823 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6824 _humongous_count.increment(1u, hr->capacity());
6825 } else if (hr->is_empty()) {
6826 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6827 _free_count.increment(1u, hr->capacity());
6828 } else {
6829 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6830 _old_count.increment(1u, hr->capacity());
6831 }
6832 return false;
6833 }
6834
6835 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6836 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6837 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6838 old_set->total_capacity_bytes(), _old_count.capacity()));
6839
6840 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6841 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6842 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6843
6844 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6845 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6846 free_list->total_capacity_bytes(), _free_count.capacity()));
6847 }
6848 };
6849
6850 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6851 HeapWord* bottom) {
6852 HeapWord* end = bottom + HeapRegion::GrainWords;
6853 MemRegion mr(bottom, end);
6854 assert(_g1_reserved.contains(mr), "invariant");
6855 // This might return NULL if the allocation fails
6856 return new HeapRegion(hrs_index, _bot_shared, mr);
6857 }
6858
6859 void G1CollectedHeap::verify_region_sets() {
6860 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6861
6862 // First, check the explicit lists.
6863 _free_list.verify_list();
6864 {
6865 // Given that a concurrent operation might be adding regions to
6866 // the secondary free list we have to take the lock before
6867 // verifying it.
6868 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6869 _secondary_free_list.verify_list();
6870 }
6871
6872 // If a concurrent region freeing operation is in progress it will
6873 // be difficult to correctly attributed any free regions we come
6874 // across to the correct free list given that they might belong to
6875 // one of several (free_list, secondary_free_list, any local lists,
6876 // etc.). So, if that's the case we will skip the rest of the
6877 // verification operation. Alternatively, waiting for the concurrent
6878 // operation to complete will have a non-trivial effect on the GC's
6879 // operation (no concurrent operation will last longer than the
6880 // interval between two calls to verification) and it might hide
6881 // any issues that we would like to catch during testing.
6882 if (free_regions_coming()) {
6883 return;
6884 }
6885
6886 // Make sure we append the secondary_free_list on the free_list so
6887 // that all free regions we will come across can be safely
6888 // attributed to the free_list.
6889 append_secondary_free_list_if_not_empty_with_lock();
6890
6891 // Finally, make sure that the region accounting in the lists is
6892 // consistent with what we see in the heap.
6893
6894 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6895 heap_region_iterate(&cl);
6896 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6897 }
6898
6899 // Optimized nmethod scanning
6900
6901 class RegisterNMethodOopClosure: public OopClosure {
6902 G1CollectedHeap* _g1h;
6903 nmethod* _nm;
6904
6905 template <class T> void do_oop_work(T* p) {
6906 T heap_oop = oopDesc::load_heap_oop(p);
6907 if (!oopDesc::is_null(heap_oop)) {
6908 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6909 HeapRegion* hr = _g1h->heap_region_containing(obj);
6910 assert(!hr->continuesHumongous(),
6911 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6912 " starting at "HR_FORMAT,
6913 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6914
6915 // HeapRegion::add_strong_code_root() avoids adding duplicate
6916 // entries but having duplicates is OK since we "mark" nmethods
6917 // as visited when we scan the strong code root lists during the GC.
6918 hr->add_strong_code_root(_nm);
6919 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6920 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6921 _nm, HR_FORMAT_PARAMS(hr)));
6922 }
6923 }
6924
6925 public:
6926 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6927 _g1h(g1h), _nm(nm) {}
6928
6929 void do_oop(oop* p) { do_oop_work(p); }
6930 void do_oop(narrowOop* p) { do_oop_work(p); }
6931 };
6932
6933 class UnregisterNMethodOopClosure: public OopClosure {
6934 G1CollectedHeap* _g1h;
6935 nmethod* _nm;
6936
6937 template <class T> void do_oop_work(T* p) {
6938 T heap_oop = oopDesc::load_heap_oop(p);
6939 if (!oopDesc::is_null(heap_oop)) {
6940 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6941 HeapRegion* hr = _g1h->heap_region_containing(obj);
6942 assert(!hr->continuesHumongous(),
6943 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6944 " starting at "HR_FORMAT,
6945 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6946
6947 hr->remove_strong_code_root(_nm);
6948 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6949 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6950 _nm, HR_FORMAT_PARAMS(hr)));
6951 }
6952 }
6953
6954 public:
6955 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6956 _g1h(g1h), _nm(nm) {}
6957
6958 void do_oop(oop* p) { do_oop_work(p); }
6959 void do_oop(narrowOop* p) { do_oop_work(p); }
6960 };
6961
6962 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6963 CollectedHeap::register_nmethod(nm);
6964
6965 guarantee(nm != NULL, "sanity");
6966 RegisterNMethodOopClosure reg_cl(this, nm);
6967 nm->oops_do(®_cl);
6968 }
6969
6970 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6971 CollectedHeap::unregister_nmethod(nm);
6972
6973 guarantee(nm != NULL, "sanity");
6974 UnregisterNMethodOopClosure reg_cl(this, nm);
6975 nm->oops_do(®_cl, true);
6976 }
6977
6978 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6979 public:
6980 bool doHeapRegion(HeapRegion *hr) {
6981 assert(!hr->isHumongous(),
6982 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6983 HR_FORMAT_PARAMS(hr)));
6984 hr->migrate_strong_code_roots();
6985 return false;
6986 }
6987 };
6988
6989 void G1CollectedHeap::migrate_strong_code_roots() {
6990 MigrateCodeRootsHeapRegionClosure cl;
6991 double migrate_start = os::elapsedTime();
6992 collection_set_iterate(&cl);
6993 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6994 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6995 }
6996
6997 void G1CollectedHeap::purge_code_root_memory() {
6998 double purge_start = os::elapsedTime();
6999 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
7000 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
7001 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
7002 }
7003
7004 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
7005 G1CollectedHeap* _g1h;
7006
7007 public:
7008 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7009 _g1h(g1h) {}
7010
7011 void do_code_blob(CodeBlob* cb) {
7012 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7013 if (nm == NULL) {
7014 return;
7015 }
7016
7017 if (ScavengeRootsInCode) {
7018 _g1h->register_nmethod(nm);
7019 }
7020 }
7021 };
7022
7023 void G1CollectedHeap::rebuild_strong_code_roots() {
7024 RebuildStrongCodeRootClosure blob_cl(this);
7025 CodeCache::blobs_do(&blob_cl);
7026 }