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 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess.
27 #endif
28
29 #include "precompiled.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "gc_implementation/g1/bufferingOopClosure.hpp"
33 #include "gc_implementation/g1/concurrentG1Refine.hpp"
34 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
35 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
36 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
37 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
38 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
39 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
40 #include "gc_implementation/g1/g1EvacFailure.hpp"
41 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
42 #include "gc_implementation/g1/g1Log.hpp"
43 #include "gc_implementation/g1/g1MarkSweep.hpp"
44 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
45 #include "gc_implementation/g1/g1RemSet.inline.hpp"
46 #include "gc_implementation/g1/g1StringDedup.hpp"
47 #include "gc_implementation/g1/g1YCTypes.hpp"
48 #include "gc_implementation/g1/heapRegion.inline.hpp"
49 #include "gc_implementation/g1/heapRegionRemSet.hpp"
50 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
51 #include "gc_implementation/g1/vm_operations_g1.hpp"
52 #include "gc_implementation/shared/gcHeapSummary.hpp"
53 #include "gc_implementation/shared/gcTimer.hpp"
54 #include "gc_implementation/shared/gcTrace.hpp"
55 #include "gc_implementation/shared/gcTraceTime.hpp"
56 #include "gc_implementation/shared/isGCActiveMark.hpp"
57 #include "memory/gcLocker.inline.hpp"
58 #include "memory/generationSpec.hpp"
59 #include "memory/iterator.hpp"
60 #include "memory/referenceProcessor.hpp"
61 #include "oops/oop.inline.hpp"
62 #include "oops/oop.pcgc.inline.hpp"
63 #include "runtime/prefetch.inline.hpp"
64 #include "runtime/orderAccess.inline.hpp"
65 #include "runtime/vmThread.hpp"
66 #include "utilities/ticks.hpp"
67
68 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
69
70 // turn it on so that the contents of the young list (scan-only /
71 // to-be-collected) are printed at "strategic" points before / during
72 // / after the collection --- this is useful for debugging
73 #define YOUNG_LIST_VERBOSE 0
74 // CURRENT STATUS
75 // This file is under construction. Search for "FIXME".
76
77 // INVARIANTS/NOTES
78 //
79 // All allocation activity covered by the G1CollectedHeap interface is
80 // serialized by acquiring the HeapLock. This happens in mem_allocate
81 // and allocate_new_tlab, which are the "entry" points to the
82 // allocation code from the rest of the JVM. (Note that this does not
83 // apply to TLAB allocation, which is not part of this interface: it
84 // is done by clients of this interface.)
85
86 // Notes on implementation of parallelism in different tasks.
87 //
88 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
89 // The number of GC workers is passed to heap_region_par_iterate_chunked().
90 // It does use run_task() which sets _n_workers in the task.
91 // G1ParTask executes g1_process_strong_roots() ->
92 // SharedHeap::process_strong_roots() which calls eventually to
93 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
94 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
95 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
96 //
97
98 // Local to this file.
99
100 class RefineCardTableEntryClosure: public CardTableEntryClosure {
101 bool _concurrent;
102 public:
103 RefineCardTableEntryClosure() : _concurrent(true) { }
104
105 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
106 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
107 // This path is executed by the concurrent refine or mutator threads,
108 // concurrently, and so we do not care if card_ptr contains references
109 // that point into the collection set.
110 assert(!oops_into_cset, "should be");
111
112 if (_concurrent && SuspendibleThreadSet::should_yield()) {
113 // Caller will actually yield.
114 return false;
115 }
116 // Otherwise, we finished successfully; return true.
117 return true;
118 }
119
120 void set_concurrent(bool b) { _concurrent = b; }
121 };
122
123
124 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
125 size_t _num_processed;
126 CardTableModRefBS* _ctbs;
127 int _histo[256];
128
129 public:
130 ClearLoggedCardTableEntryClosure() :
131 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
132 {
133 for (int i = 0; i < 256; i++) _histo[i] = 0;
134 }
135
136 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
137 unsigned char* ujb = (unsigned char*)card_ptr;
138 int ind = (int)(*ujb);
139 _histo[ind]++;
140
141 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
142 _num_processed++;
143
144 return true;
145 }
146
147 size_t num_processed() { return _num_processed; }
148
149 void print_histo() {
150 gclog_or_tty->print_cr("Card table value histogram:");
151 for (int i = 0; i < 256; i++) {
152 if (_histo[i] != 0) {
153 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
154 }
155 }
156 }
157 };
158
159 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
160 private:
161 size_t _num_processed;
162
163 public:
164 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
165
166 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
167 *card_ptr = CardTableModRefBS::dirty_card_val();
168 _num_processed++;
169 return true;
170 }
171
172 size_t num_processed() const { return _num_processed; }
173 };
174
175 YoungList::YoungList(G1CollectedHeap* g1h) :
176 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
177 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
178 guarantee(check_list_empty(false), "just making sure...");
179 }
180
181 void YoungList::push_region(HeapRegion *hr) {
182 assert(!hr->is_young(), "should not already be young");
183 assert(hr->get_next_young_region() == NULL, "cause it should!");
184
185 hr->set_next_young_region(_head);
186 _head = hr;
187
188 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
189 ++_length;
190 }
191
192 void YoungList::add_survivor_region(HeapRegion* hr) {
193 assert(hr->is_survivor(), "should be flagged as survivor region");
194 assert(hr->get_next_young_region() == NULL, "cause it should!");
195
196 hr->set_next_young_region(_survivor_head);
197 if (_survivor_head == NULL) {
198 _survivor_tail = hr;
199 }
200 _survivor_head = hr;
201 ++_survivor_length;
202 }
203
204 void YoungList::empty_list(HeapRegion* list) {
205 while (list != NULL) {
206 HeapRegion* next = list->get_next_young_region();
207 list->set_next_young_region(NULL);
208 list->uninstall_surv_rate_group();
209 list->set_not_young();
210 list = next;
211 }
212 }
213
214 void YoungList::empty_list() {
215 assert(check_list_well_formed(), "young list should be well formed");
216
217 empty_list(_head);
218 _head = NULL;
219 _length = 0;
220
221 empty_list(_survivor_head);
222 _survivor_head = NULL;
223 _survivor_tail = NULL;
224 _survivor_length = 0;
225
226 _last_sampled_rs_lengths = 0;
227
228 assert(check_list_empty(false), "just making sure...");
229 }
230
231 bool YoungList::check_list_well_formed() {
232 bool ret = true;
233
234 uint length = 0;
235 HeapRegion* curr = _head;
236 HeapRegion* last = NULL;
237 while (curr != NULL) {
238 if (!curr->is_young()) {
239 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
240 "incorrectly tagged (y: %d, surv: %d)",
241 curr->bottom(), curr->end(),
242 curr->is_young(), curr->is_survivor());
243 ret = false;
244 }
245 ++length;
246 last = curr;
247 curr = curr->get_next_young_region();
248 }
249 ret = ret && (length == _length);
250
251 if (!ret) {
252 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
253 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
254 length, _length);
255 }
256
257 return ret;
258 }
259
260 bool YoungList::check_list_empty(bool check_sample) {
261 bool ret = true;
262
263 if (_length != 0) {
264 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
265 _length);
266 ret = false;
267 }
268 if (check_sample && _last_sampled_rs_lengths != 0) {
269 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
270 ret = false;
271 }
272 if (_head != NULL) {
273 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
274 ret = false;
275 }
276 if (!ret) {
277 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
278 }
279
280 return ret;
281 }
282
283 void
284 YoungList::rs_length_sampling_init() {
285 _sampled_rs_lengths = 0;
286 _curr = _head;
287 }
288
289 bool
290 YoungList::rs_length_sampling_more() {
291 return _curr != NULL;
292 }
293
294 void
295 YoungList::rs_length_sampling_next() {
296 assert( _curr != NULL, "invariant" );
297 size_t rs_length = _curr->rem_set()->occupied();
298
299 _sampled_rs_lengths += rs_length;
300
301 // The current region may not yet have been added to the
302 // incremental collection set (it gets added when it is
303 // retired as the current allocation region).
304 if (_curr->in_collection_set()) {
305 // Update the collection set policy information for this region
306 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
307 }
308
309 _curr = _curr->get_next_young_region();
310 if (_curr == NULL) {
311 _last_sampled_rs_lengths = _sampled_rs_lengths;
312 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
313 }
314 }
315
316 void
317 YoungList::reset_auxilary_lists() {
318 guarantee( is_empty(), "young list should be empty" );
319 assert(check_list_well_formed(), "young list should be well formed");
320
321 // Add survivor regions to SurvRateGroup.
322 _g1h->g1_policy()->note_start_adding_survivor_regions();
323 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
324
325 int young_index_in_cset = 0;
326 for (HeapRegion* curr = _survivor_head;
327 curr != NULL;
328 curr = curr->get_next_young_region()) {
329 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
330
331 // The region is a non-empty survivor so let's add it to
332 // the incremental collection set for the next evacuation
333 // pause.
334 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
335 young_index_in_cset += 1;
336 }
337 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
338 _g1h->g1_policy()->note_stop_adding_survivor_regions();
339
340 _head = _survivor_head;
341 _length = _survivor_length;
342 if (_survivor_head != NULL) {
343 assert(_survivor_tail != NULL, "cause it shouldn't be");
344 assert(_survivor_length > 0, "invariant");
345 _survivor_tail->set_next_young_region(NULL);
346 }
347
348 // Don't clear the survivor list handles until the start of
349 // the next evacuation pause - we need it in order to re-tag
350 // the survivor regions from this evacuation pause as 'young'
351 // at the start of the next.
352
353 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
354
355 assert(check_list_well_formed(), "young list should be well formed");
356 }
357
358 void YoungList::print() {
359 HeapRegion* lists[] = {_head, _survivor_head};
360 const char* names[] = {"YOUNG", "SURVIVOR"};
361
362 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
363 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
364 HeapRegion *curr = lists[list];
365 if (curr == NULL)
366 gclog_or_tty->print_cr(" empty");
367 while (curr != NULL) {
368 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
369 HR_FORMAT_PARAMS(curr),
370 curr->prev_top_at_mark_start(),
371 curr->next_top_at_mark_start(),
372 curr->age_in_surv_rate_group_cond());
373 curr = curr->get_next_young_region();
374 }
375 }
376
377 gclog_or_tty->cr();
378 }
379
380 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
381 {
382 // Claim the right to put the region on the dirty cards region list
383 // by installing a self pointer.
384 HeapRegion* next = hr->get_next_dirty_cards_region();
385 if (next == NULL) {
386 HeapRegion* res = (HeapRegion*)
387 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
388 NULL);
389 if (res == NULL) {
390 HeapRegion* head;
391 do {
392 // Put the region to the dirty cards region list.
393 head = _dirty_cards_region_list;
394 next = (HeapRegion*)
395 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
396 if (next == head) {
397 assert(hr->get_next_dirty_cards_region() == hr,
398 "hr->get_next_dirty_cards_region() != hr");
399 if (next == NULL) {
400 // The last region in the list points to itself.
401 hr->set_next_dirty_cards_region(hr);
402 } else {
403 hr->set_next_dirty_cards_region(next);
404 }
405 }
406 } while (next != head);
407 }
408 }
409 }
410
411 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
412 {
413 HeapRegion* head;
414 HeapRegion* hr;
415 do {
416 head = _dirty_cards_region_list;
417 if (head == NULL) {
418 return NULL;
419 }
420 HeapRegion* new_head = head->get_next_dirty_cards_region();
421 if (head == new_head) {
422 // The last region.
423 new_head = NULL;
424 }
425 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
426 head);
427 } while (hr != head);
428 assert(hr != NULL, "invariant");
429 hr->set_next_dirty_cards_region(NULL);
430 return hr;
431 }
432
433 #ifdef ASSERT
434 // A region is added to the collection set as it is retired
435 // so an address p can point to a region which will be in the
436 // collection set but has not yet been retired. This method
437 // therefore is only accurate during a GC pause after all
438 // regions have been retired. It is used for debugging
439 // to check if an nmethod has references to objects that can
440 // be move during a partial collection. Though it can be
441 // inaccurate, it is sufficient for G1 because the conservative
442 // implementation of is_scavengable() for G1 will indicate that
443 // all nmethods must be scanned during a partial collection.
444 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
445 HeapRegion* hr = heap_region_containing(p);
446 return hr != NULL && hr->in_collection_set();
447 }
448 #endif
449
450 // Returns true if the reference points to an object that
451 // can move in an incremental collection.
452 bool G1CollectedHeap::is_scavengable(const void* p) {
453 G1CollectedHeap* g1h = G1CollectedHeap::heap();
454 G1CollectorPolicy* g1p = g1h->g1_policy();
455 HeapRegion* hr = heap_region_containing(p);
456 if (hr == NULL) {
457 // null
458 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
459 return false;
460 } else {
461 return !hr->isHumongous();
462 }
463 }
464
465 void G1CollectedHeap::check_ct_logs_at_safepoint() {
466 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
467 CardTableModRefBS* ct_bs = g1_barrier_set();
468
469 // Count the dirty cards at the start.
470 CountNonCleanMemRegionClosure count1(this);
471 ct_bs->mod_card_iterate(&count1);
472 int orig_count = count1.n();
473
474 // First clear the logged cards.
475 ClearLoggedCardTableEntryClosure clear;
476 dcqs.apply_closure_to_all_completed_buffers(&clear);
477 dcqs.iterate_closure_all_threads(&clear, false);
478 clear.print_histo();
479
480 // Now ensure that there's no dirty cards.
481 CountNonCleanMemRegionClosure count2(this);
482 ct_bs->mod_card_iterate(&count2);
483 if (count2.n() != 0) {
484 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
485 count2.n(), orig_count);
486 }
487 guarantee(count2.n() == 0, "Card table should be clean.");
488
489 RedirtyLoggedCardTableEntryClosure redirty;
490 dcqs.apply_closure_to_all_completed_buffers(&redirty);
491 dcqs.iterate_closure_all_threads(&redirty, false);
492 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
493 clear.num_processed(), orig_count);
494 guarantee(redirty.num_processed() == clear.num_processed(),
495 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
496 redirty.num_processed(), clear.num_processed()));
497
498 CountNonCleanMemRegionClosure count3(this);
499 ct_bs->mod_card_iterate(&count3);
500 if (count3.n() != orig_count) {
501 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
502 orig_count, count3.n());
503 guarantee(count3.n() >= orig_count, "Should have restored them all.");
504 }
505 }
506
507 // Private class members.
508
509 G1CollectedHeap* G1CollectedHeap::_g1h;
510
511 // Private methods.
512
513 HeapRegion*
514 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
515 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
516 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
517 if (!_secondary_free_list.is_empty()) {
518 if (G1ConcRegionFreeingVerbose) {
519 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
520 "secondary_free_list has %u entries",
521 _secondary_free_list.length());
522 }
523 // It looks as if there are free regions available on the
524 // secondary_free_list. Let's move them to the free_list and try
525 // again to allocate from it.
526 append_secondary_free_list();
527
528 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
529 "empty we should have moved at least one entry to the free_list");
530 HeapRegion* res = _free_list.remove_region(is_old);
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "allocated "HR_FORMAT" from secondary_free_list",
534 HR_FORMAT_PARAMS(res));
535 }
536 return res;
537 }
538
539 // Wait here until we get notified either when (a) there are no
540 // more free regions coming or (b) some regions have been moved on
541 // the secondary_free_list.
542 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
543 }
544
545 if (G1ConcRegionFreeingVerbose) {
546 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
547 "could not allocate from secondary_free_list");
548 }
549 return NULL;
550 }
551
552 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
553 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
554 "the only time we use this to allocate a humongous region is "
555 "when we are allocating a single humongous region");
556
557 HeapRegion* res;
558 if (G1StressConcRegionFreeing) {
559 if (!_secondary_free_list.is_empty()) {
560 if (G1ConcRegionFreeingVerbose) {
561 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
562 "forced to look at the secondary_free_list");
563 }
564 res = new_region_try_secondary_free_list(is_old);
565 if (res != NULL) {
566 return res;
567 }
568 }
569 }
570
571 res = _free_list.remove_region(is_old);
572
573 if (res == NULL) {
574 if (G1ConcRegionFreeingVerbose) {
575 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
576 "res == NULL, trying the secondary_free_list");
577 }
578 res = new_region_try_secondary_free_list(is_old);
579 }
580 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
581 // Currently, only attempts to allocate GC alloc regions set
582 // do_expand to true. So, we should only reach here during a
583 // safepoint. If this assumption changes we might have to
584 // reconsider the use of _expand_heap_after_alloc_failure.
585 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
586
587 ergo_verbose1(ErgoHeapSizing,
588 "attempt heap expansion",
589 ergo_format_reason("region allocation request failed")
590 ergo_format_byte("allocation request"),
591 word_size * HeapWordSize);
592 if (expand(word_size * HeapWordSize)) {
593 // Given that expand() succeeded in expanding the heap, and we
594 // always expand the heap by an amount aligned to the heap
595 // region size, the free list should in theory not be empty.
596 // In either case remove_region() will check for NULL.
597 res = _free_list.remove_region(is_old);
598 } else {
599 _expand_heap_after_alloc_failure = false;
600 }
601 }
602 return res;
603 }
604
605 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
606 size_t word_size) {
607 assert(isHumongous(word_size), "word_size should be humongous");
608 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
609
610 uint first = G1_NULL_HRS_INDEX;
611 if (num_regions == 1) {
612 // Only one region to allocate, no need to go through the slower
613 // path. The caller will attempt the expansion if this fails, so
614 // let's not try to expand here too.
615 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
616 if (hr != NULL) {
617 first = hr->hrs_index();
618 } else {
619 first = G1_NULL_HRS_INDEX;
620 }
621 } else {
622 // We can't allocate humongous regions while cleanupComplete() is
623 // running, since some of the regions we find to be empty might not
624 // yet be added to the free list and it is not straightforward to
625 // know which list they are on so that we can remove them. Note
626 // that we only need to do this if we need to allocate more than
627 // one region to satisfy the current humongous allocation
628 // request. If we are only allocating one region we use the common
629 // region allocation code (see above).
630 wait_while_free_regions_coming();
631 append_secondary_free_list_if_not_empty_with_lock();
632
633 if (free_regions() >= num_regions) {
634 first = _hrs.find_contiguous(num_regions);
635 if (first != G1_NULL_HRS_INDEX) {
636 for (uint i = first; i < first + num_regions; ++i) {
637 HeapRegion* hr = region_at(i);
638 assert(hr->is_empty(), "sanity");
639 assert(is_on_master_free_list(hr), "sanity");
640 hr->set_pending_removal(true);
641 }
642 _free_list.remove_all_pending(num_regions);
643 }
644 }
645 }
646 return first;
647 }
648
649 HeapWord*
650 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
651 uint num_regions,
652 size_t word_size) {
653 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
654 assert(isHumongous(word_size), "word_size should be humongous");
655 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
656
657 // Index of last region in the series + 1.
658 uint last = first + num_regions;
659
660 // We need to initialize the region(s) we just discovered. This is
661 // a bit tricky given that it can happen concurrently with
662 // refinement threads refining cards on these regions and
663 // potentially wanting to refine the BOT as they are scanning
664 // those cards (this can happen shortly after a cleanup; see CR
665 // 6991377). So we have to set up the region(s) carefully and in
666 // a specific order.
667
668 // The word size sum of all the regions we will allocate.
669 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
670 assert(word_size <= word_size_sum, "sanity");
671
672 // This will be the "starts humongous" region.
673 HeapRegion* first_hr = region_at(first);
674 // The header of the new object will be placed at the bottom of
675 // the first region.
676 HeapWord* new_obj = first_hr->bottom();
677 // This will be the new end of the first region in the series that
678 // should also match the end of the last region in the series.
679 HeapWord* new_end = new_obj + word_size_sum;
680 // This will be the new top of the first region that will reflect
681 // this allocation.
682 HeapWord* new_top = new_obj + word_size;
683
684 // First, we need to zero the header of the space that we will be
685 // allocating. When we update top further down, some refinement
686 // threads might try to scan the region. By zeroing the header we
687 // ensure that any thread that will try to scan the region will
688 // come across the zero klass word and bail out.
689 //
690 // NOTE: It would not have been correct to have used
691 // CollectedHeap::fill_with_object() and make the space look like
692 // an int array. The thread that is doing the allocation will
693 // later update the object header to a potentially different array
694 // type and, for a very short period of time, the klass and length
695 // fields will be inconsistent. This could cause a refinement
696 // thread to calculate the object size incorrectly.
697 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
698
699 // We will set up the first region as "starts humongous". This
700 // will also update the BOT covering all the regions to reflect
701 // that there is a single object that starts at the bottom of the
702 // first region.
703 first_hr->set_startsHumongous(new_top, new_end);
704
705 // Then, if there are any, we will set up the "continues
706 // humongous" regions.
707 HeapRegion* hr = NULL;
708 for (uint i = first + 1; i < last; ++i) {
709 hr = region_at(i);
710 hr->set_continuesHumongous(first_hr);
711 }
712 // If we have "continues humongous" regions (hr != NULL), then the
713 // end of the last one should match new_end.
714 assert(hr == NULL || hr->end() == new_end, "sanity");
715
716 // Up to this point no concurrent thread would have been able to
717 // do any scanning on any region in this series. All the top
718 // fields still point to bottom, so the intersection between
719 // [bottom,top] and [card_start,card_end] will be empty. Before we
720 // update the top fields, we'll do a storestore to make sure that
721 // no thread sees the update to top before the zeroing of the
722 // object header and the BOT initialization.
723 OrderAccess::storestore();
724
725 // Now that the BOT and the object header have been initialized,
726 // we can update top of the "starts humongous" region.
727 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
728 "new_top should be in this region");
729 first_hr->set_top(new_top);
730 if (_hr_printer.is_active()) {
731 HeapWord* bottom = first_hr->bottom();
732 HeapWord* end = first_hr->orig_end();
733 if ((first + 1) == last) {
734 // the series has a single humongous region
735 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
736 } else {
737 // the series has more than one humongous regions
738 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
739 }
740 }
741
742 // Now, we will update the top fields of the "continues humongous"
743 // regions. The reason we need to do this is that, otherwise,
744 // these regions would look empty and this will confuse parts of
745 // G1. For example, the code that looks for a consecutive number
746 // of empty regions will consider them empty and try to
747 // re-allocate them. We can extend is_empty() to also include
748 // !continuesHumongous(), but it is easier to just update the top
749 // fields here. The way we set top for all regions (i.e., top ==
750 // end for all regions but the last one, top == new_top for the
751 // last one) is actually used when we will free up the humongous
752 // region in free_humongous_region().
753 hr = NULL;
754 for (uint i = first + 1; i < last; ++i) {
755 hr = region_at(i);
756 if ((i + 1) == last) {
757 // last continues humongous region
758 assert(hr->bottom() < new_top && new_top <= hr->end(),
759 "new_top should fall on this region");
760 hr->set_top(new_top);
761 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
762 } else {
763 // not last one
764 assert(new_top > hr->end(), "new_top should be above this region");
765 hr->set_top(hr->end());
766 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
767 }
768 }
769 // If we have continues humongous regions (hr != NULL), then the
770 // end of the last one should match new_end and its top should
771 // match new_top.
772 assert(hr == NULL ||
773 (hr->end() == new_end && hr->top() == new_top), "sanity");
774
775 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
776 _summary_bytes_used += first_hr->used();
777 _humongous_set.add(first_hr);
778
779 return new_obj;
780 }
781
782 // If could fit into free regions w/o expansion, try.
783 // Otherwise, if can expand, do so.
784 // Otherwise, if using ex regions might help, try with ex given back.
785 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
786 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
787
788 verify_region_sets_optional();
789
790 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
791 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
792 uint x_num = expansion_regions();
793 uint fs = _hrs.free_suffix();
794 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
795 if (first == G1_NULL_HRS_INDEX) {
796 // The only thing we can do now is attempt expansion.
797 if (fs + x_num >= num_regions) {
798 // If the number of regions we're trying to allocate for this
799 // object is at most the number of regions in the free suffix,
800 // then the call to humongous_obj_allocate_find_first() above
801 // should have succeeded and we wouldn't be here.
802 //
803 // We should only be trying to expand when the free suffix is
804 // not sufficient for the object _and_ we have some expansion
805 // room available.
806 assert(num_regions > fs, "earlier allocation should have succeeded");
807
808 ergo_verbose1(ErgoHeapSizing,
809 "attempt heap expansion",
810 ergo_format_reason("humongous allocation request failed")
811 ergo_format_byte("allocation request"),
812 word_size * HeapWordSize);
813 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
814 // Even though the heap was expanded, it might not have
815 // reached the desired size. So, we cannot assume that the
816 // allocation will succeed.
817 first = humongous_obj_allocate_find_first(num_regions, word_size);
818 }
819 }
820 }
821
822 HeapWord* result = NULL;
823 if (first != G1_NULL_HRS_INDEX) {
824 result =
825 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
826 assert(result != NULL, "it should always return a valid result");
827
828 // A successful humongous object allocation changes the used space
829 // information of the old generation so we need to recalculate the
830 // sizes and update the jstat counters here.
831 g1mm()->update_sizes();
832 }
833
834 verify_region_sets_optional();
835
836 return result;
837 }
838
839 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
840 assert_heap_not_locked_and_not_at_safepoint();
841 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
842
843 unsigned int dummy_gc_count_before;
844 int dummy_gclocker_retry_count = 0;
845 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
846 }
847
848 HeapWord*
849 G1CollectedHeap::mem_allocate(size_t word_size,
850 bool* gc_overhead_limit_was_exceeded) {
851 assert_heap_not_locked_and_not_at_safepoint();
852
853 // Loop until the allocation is satisfied, or unsatisfied after GC.
854 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
855 unsigned int gc_count_before;
856
857 HeapWord* result = NULL;
858 if (!isHumongous(word_size)) {
859 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
860 } else {
861 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
862 }
863 if (result != NULL) {
864 return result;
865 }
866
867 // Create the garbage collection operation...
868 VM_G1CollectForAllocation op(gc_count_before, word_size);
869 // ...and get the VM thread to execute it.
870 VMThread::execute(&op);
871
872 if (op.prologue_succeeded() && op.pause_succeeded()) {
873 // If the operation was successful we'll return the result even
874 // if it is NULL. If the allocation attempt failed immediately
875 // after a Full GC, it's unlikely we'll be able to allocate now.
876 HeapWord* result = op.result();
877 if (result != NULL && !isHumongous(word_size)) {
878 // Allocations that take place on VM operations do not do any
879 // card dirtying and we have to do it here. We only have to do
880 // this for non-humongous allocations, though.
881 dirty_young_block(result, word_size);
882 }
883 return result;
884 } else {
885 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
886 return NULL;
887 }
888 assert(op.result() == NULL,
889 "the result should be NULL if the VM op did not succeed");
890 }
891
892 // Give a warning if we seem to be looping forever.
893 if ((QueuedAllocationWarningCount > 0) &&
894 (try_count % QueuedAllocationWarningCount == 0)) {
895 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
896 }
897 }
898
899 ShouldNotReachHere();
900 return NULL;
901 }
902
903 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
904 unsigned int *gc_count_before_ret,
905 int* gclocker_retry_count_ret) {
906 // Make sure you read the note in attempt_allocation_humongous().
907
908 assert_heap_not_locked_and_not_at_safepoint();
909 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
910 "be called for humongous allocation requests");
911
912 // We should only get here after the first-level allocation attempt
913 // (attempt_allocation()) failed to allocate.
914
915 // We will loop until a) we manage to successfully perform the
916 // allocation or b) we successfully schedule a collection which
917 // fails to perform the allocation. b) is the only case when we'll
918 // return NULL.
919 HeapWord* result = NULL;
920 for (int try_count = 1; /* we'll return */; try_count += 1) {
921 bool should_try_gc;
922 unsigned int gc_count_before;
923
924 {
925 MutexLockerEx x(Heap_lock);
926
927 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
928 false /* bot_updates */);
929 if (result != NULL) {
930 return result;
931 }
932
933 // If we reach here, attempt_allocation_locked() above failed to
934 // allocate a new region. So the mutator alloc region should be NULL.
935 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
936
937 if (GC_locker::is_active_and_needs_gc()) {
938 if (g1_policy()->can_expand_young_list()) {
939 // No need for an ergo verbose message here,
940 // can_expand_young_list() does this when it returns true.
941 result = _mutator_alloc_region.attempt_allocation_force(word_size,
942 false /* bot_updates */);
943 if (result != NULL) {
944 return result;
945 }
946 }
947 should_try_gc = false;
948 } else {
949 // The GCLocker may not be active but the GCLocker initiated
950 // GC may not yet have been performed (GCLocker::needs_gc()
951 // returns true). In this case we do not try this GC and
952 // wait until the GCLocker initiated GC is performed, and
953 // then retry the allocation.
954 if (GC_locker::needs_gc()) {
955 should_try_gc = false;
956 } else {
957 // Read the GC count while still holding the Heap_lock.
958 gc_count_before = total_collections();
959 should_try_gc = true;
960 }
961 }
962 }
963
964 if (should_try_gc) {
965 bool succeeded;
966 result = do_collection_pause(word_size, gc_count_before, &succeeded,
967 GCCause::_g1_inc_collection_pause);
968 if (result != NULL) {
969 assert(succeeded, "only way to get back a non-NULL result");
970 return result;
971 }
972
973 if (succeeded) {
974 // If we get here we successfully scheduled a collection which
975 // failed to allocate. No point in trying to allocate
976 // further. We'll just return NULL.
977 MutexLockerEx x(Heap_lock);
978 *gc_count_before_ret = total_collections();
979 return NULL;
980 }
981 } else {
982 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
983 MutexLockerEx x(Heap_lock);
984 *gc_count_before_ret = total_collections();
985 return NULL;
986 }
987 // The GCLocker is either active or the GCLocker initiated
988 // GC has not yet been performed. Stall until it is and
989 // then retry the allocation.
990 GC_locker::stall_until_clear();
991 (*gclocker_retry_count_ret) += 1;
992 }
993
994 // We can reach here if we were unsuccessful in scheduling a
995 // collection (because another thread beat us to it) or if we were
996 // stalled due to the GC locker. In either can we should retry the
997 // allocation attempt in case another thread successfully
998 // performed a collection and reclaimed enough space. We do the
999 // first attempt (without holding the Heap_lock) here and the
1000 // follow-on attempt will be at the start of the next loop
1001 // iteration (after taking the Heap_lock).
1002 result = _mutator_alloc_region.attempt_allocation(word_size,
1003 false /* bot_updates */);
1004 if (result != NULL) {
1005 return result;
1006 }
1007
1008 // Give a warning if we seem to be looping forever.
1009 if ((QueuedAllocationWarningCount > 0) &&
1010 (try_count % QueuedAllocationWarningCount == 0)) {
1011 warning("G1CollectedHeap::attempt_allocation_slow() "
1012 "retries %d times", try_count);
1013 }
1014 }
1015
1016 ShouldNotReachHere();
1017 return NULL;
1018 }
1019
1020 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1021 unsigned int * gc_count_before_ret,
1022 int* gclocker_retry_count_ret) {
1023 // The structure of this method has a lot of similarities to
1024 // attempt_allocation_slow(). The reason these two were not merged
1025 // into a single one is that such a method would require several "if
1026 // allocation is not humongous do this, otherwise do that"
1027 // conditional paths which would obscure its flow. In fact, an early
1028 // version of this code did use a unified method which was harder to
1029 // follow and, as a result, it had subtle bugs that were hard to
1030 // track down. So keeping these two methods separate allows each to
1031 // be more readable. It will be good to keep these two in sync as
1032 // much as possible.
1033
1034 assert_heap_not_locked_and_not_at_safepoint();
1035 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1036 "should only be called for humongous allocations");
1037
1038 // Humongous objects can exhaust the heap quickly, so we should check if we
1039 // need to start a marking cycle at each humongous object allocation. We do
1040 // the check before we do the actual allocation. The reason for doing it
1041 // before the allocation is that we avoid having to keep track of the newly
1042 // allocated memory while we do a GC.
1043 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1044 word_size)) {
1045 collect(GCCause::_g1_humongous_allocation);
1046 }
1047
1048 // We will loop until a) we manage to successfully perform the
1049 // allocation or b) we successfully schedule a collection which
1050 // fails to perform the allocation. b) is the only case when we'll
1051 // return NULL.
1052 HeapWord* result = NULL;
1053 for (int try_count = 1; /* we'll return */; try_count += 1) {
1054 bool should_try_gc;
1055 unsigned int gc_count_before;
1056
1057 {
1058 MutexLockerEx x(Heap_lock);
1059
1060 // Given that humongous objects are not allocated in young
1061 // regions, we'll first try to do the allocation without doing a
1062 // collection hoping that there's enough space in the heap.
1063 result = humongous_obj_allocate(word_size);
1064 if (result != NULL) {
1065 return result;
1066 }
1067
1068 if (GC_locker::is_active_and_needs_gc()) {
1069 should_try_gc = false;
1070 } else {
1071 // The GCLocker may not be active but the GCLocker initiated
1072 // GC may not yet have been performed (GCLocker::needs_gc()
1073 // returns true). In this case we do not try this GC and
1074 // wait until the GCLocker initiated GC is performed, and
1075 // then retry the allocation.
1076 if (GC_locker::needs_gc()) {
1077 should_try_gc = false;
1078 } else {
1079 // Read the GC count while still holding the Heap_lock.
1080 gc_count_before = total_collections();
1081 should_try_gc = true;
1082 }
1083 }
1084 }
1085
1086 if (should_try_gc) {
1087 // If we failed to allocate the humongous object, we should try to
1088 // do a collection pause (if we're allowed) in case it reclaims
1089 // enough space for the allocation to succeed after the pause.
1090
1091 bool succeeded;
1092 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1093 GCCause::_g1_humongous_allocation);
1094 if (result != NULL) {
1095 assert(succeeded, "only way to get back a non-NULL result");
1096 return result;
1097 }
1098
1099 if (succeeded) {
1100 // If we get here we successfully scheduled a collection which
1101 // failed to allocate. No point in trying to allocate
1102 // further. We'll just return NULL.
1103 MutexLockerEx x(Heap_lock);
1104 *gc_count_before_ret = total_collections();
1105 return NULL;
1106 }
1107 } else {
1108 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1109 MutexLockerEx x(Heap_lock);
1110 *gc_count_before_ret = total_collections();
1111 return NULL;
1112 }
1113 // The GCLocker is either active or the GCLocker initiated
1114 // GC has not yet been performed. Stall until it is and
1115 // then retry the allocation.
1116 GC_locker::stall_until_clear();
1117 (*gclocker_retry_count_ret) += 1;
1118 }
1119
1120 // We can reach here if we were unsuccessful in scheduling a
1121 // collection (because another thread beat us to it) or if we were
1122 // stalled due to the GC locker. In either can we should retry the
1123 // allocation attempt in case another thread successfully
1124 // performed a collection and reclaimed enough space. Give a
1125 // warning if we seem to be looping forever.
1126
1127 if ((QueuedAllocationWarningCount > 0) &&
1128 (try_count % QueuedAllocationWarningCount == 0)) {
1129 warning("G1CollectedHeap::attempt_allocation_humongous() "
1130 "retries %d times", try_count);
1131 }
1132 }
1133
1134 ShouldNotReachHere();
1135 return NULL;
1136 }
1137
1138 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1139 bool expect_null_mutator_alloc_region) {
1140 assert_at_safepoint(true /* should_be_vm_thread */);
1141 assert(_mutator_alloc_region.get() == NULL ||
1142 !expect_null_mutator_alloc_region,
1143 "the current alloc region was unexpectedly found to be non-NULL");
1144
1145 if (!isHumongous(word_size)) {
1146 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1147 false /* bot_updates */);
1148 } else {
1149 HeapWord* result = humongous_obj_allocate(word_size);
1150 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1151 g1_policy()->set_initiate_conc_mark_if_possible();
1152 }
1153 return result;
1154 }
1155
1156 ShouldNotReachHere();
1157 }
1158
1159 class PostMCRemSetClearClosure: public HeapRegionClosure {
1160 G1CollectedHeap* _g1h;
1161 ModRefBarrierSet* _mr_bs;
1162 public:
1163 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1164 _g1h(g1h), _mr_bs(mr_bs) {}
1165
1166 bool doHeapRegion(HeapRegion* r) {
1167 HeapRegionRemSet* hrrs = r->rem_set();
1168
1169 if (r->continuesHumongous()) {
1170 // We'll assert that the strong code root list and RSet is empty
1171 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1172 assert(hrrs->occupied() == 0, "RSet should be empty");
1173 return false;
1174 }
1175
1176 _g1h->reset_gc_time_stamps(r);
1177 hrrs->clear();
1178 // You might think here that we could clear just the cards
1179 // corresponding to the used region. But no: if we leave a dirty card
1180 // in a region we might allocate into, then it would prevent that card
1181 // from being enqueued, and cause it to be missed.
1182 // Re: the performance cost: we shouldn't be doing full GC anyway!
1183 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1184
1185 return false;
1186 }
1187 };
1188
1189 void G1CollectedHeap::clear_rsets_post_compaction() {
1190 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1191 heap_region_iterate(&rs_clear);
1192 }
1193
1194 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1195 G1CollectedHeap* _g1h;
1196 UpdateRSOopClosure _cl;
1197 int _worker_i;
1198 public:
1199 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1200 _cl(g1->g1_rem_set(), worker_i),
1201 _worker_i(worker_i),
1202 _g1h(g1)
1203 { }
1204
1205 bool doHeapRegion(HeapRegion* r) {
1206 if (!r->continuesHumongous()) {
1207 _cl.set_from(r);
1208 r->oop_iterate(&_cl);
1209 }
1210 return false;
1211 }
1212 };
1213
1214 class ParRebuildRSTask: public AbstractGangTask {
1215 G1CollectedHeap* _g1;
1216 public:
1217 ParRebuildRSTask(G1CollectedHeap* g1)
1218 : AbstractGangTask("ParRebuildRSTask"),
1219 _g1(g1)
1220 { }
1221
1222 void work(uint worker_id) {
1223 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1224 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1225 _g1->workers()->active_workers(),
1226 HeapRegion::RebuildRSClaimValue);
1227 }
1228 };
1229
1230 class PostCompactionPrinterClosure: public HeapRegionClosure {
1231 private:
1232 G1HRPrinter* _hr_printer;
1233 public:
1234 bool doHeapRegion(HeapRegion* hr) {
1235 assert(!hr->is_young(), "not expecting to find young regions");
1236 // We only generate output for non-empty regions.
1237 if (!hr->is_empty()) {
1238 if (!hr->isHumongous()) {
1239 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1240 } else if (hr->startsHumongous()) {
1241 if (hr->region_num() == 1) {
1242 // single humongous region
1243 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1244 } else {
1245 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1246 }
1247 } else {
1248 assert(hr->continuesHumongous(), "only way to get here");
1249 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1250 }
1251 }
1252 return false;
1253 }
1254
1255 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1256 : _hr_printer(hr_printer) { }
1257 };
1258
1259 void G1CollectedHeap::print_hrs_post_compaction() {
1260 PostCompactionPrinterClosure cl(hr_printer());
1261 heap_region_iterate(&cl);
1262 }
1263
1264 bool G1CollectedHeap::do_collection(bool explicit_gc,
1265 bool clear_all_soft_refs,
1266 size_t word_size) {
1267 assert_at_safepoint(true /* should_be_vm_thread */);
1268
1269 if (GC_locker::check_active_before_gc()) {
1270 return false;
1271 }
1272
1273 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1274 gc_timer->register_gc_start();
1275
1276 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1277 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1278
1279 SvcGCMarker sgcm(SvcGCMarker::FULL);
1280 ResourceMark rm;
1281
1282 print_heap_before_gc();
1283 trace_heap_before_gc(gc_tracer);
1284
1285 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1286
1287 verify_region_sets_optional();
1288
1289 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1290 collector_policy()->should_clear_all_soft_refs();
1291
1292 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1293
1294 {
1295 IsGCActiveMark x;
1296
1297 // Timing
1298 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1299 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1300 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1301
1302 {
1303 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1304 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1305 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1306
1307 double start = os::elapsedTime();
1308 g1_policy()->record_full_collection_start();
1309
1310 // Note: When we have a more flexible GC logging framework that
1311 // allows us to add optional attributes to a GC log record we
1312 // could consider timing and reporting how long we wait in the
1313 // following two methods.
1314 wait_while_free_regions_coming();
1315 // If we start the compaction before the CM threads finish
1316 // scanning the root regions we might trip them over as we'll
1317 // be moving objects / updating references. So let's wait until
1318 // they are done. By telling them to abort, they should complete
1319 // early.
1320 _cm->root_regions()->abort();
1321 _cm->root_regions()->wait_until_scan_finished();
1322 append_secondary_free_list_if_not_empty_with_lock();
1323
1324 gc_prologue(true);
1325 increment_total_collections(true /* full gc */);
1326 increment_old_marking_cycles_started();
1327
1328 assert(used() == recalculate_used(), "Should be equal");
1329
1330 verify_before_gc();
1331
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 // Start a new incremental collection set for the next pause
1506 assert(g1_policy()->collection_set() == NULL, "must be");
1507 g1_policy()->start_incremental_cset_building();
1508
1509 clear_cset_fast_test();
1510
1511 init_mutator_alloc_region();
1512
1513 double end = os::elapsedTime();
1514 g1_policy()->record_full_collection_end();
1515
1516 if (G1Log::fine()) {
1517 g1_policy()->print_heap_transition();
1518 }
1519
1520 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1521 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1522 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1523 // before any GC notifications are raised.
1524 g1mm()->update_sizes();
1525
1526 gc_epilogue(true);
1527 }
1528
1529 if (G1Log::finer()) {
1530 g1_policy()->print_detailed_heap_transition(true /* full */);
1531 }
1532
1533 print_heap_after_gc();
1534 trace_heap_after_gc(gc_tracer);
1535
1536 post_full_gc_dump(gc_timer);
1537
1538 gc_timer->register_gc_end();
1539 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1540 }
1541
1542 return true;
1543 }
1544
1545 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1546 // do_collection() will return whether it succeeded in performing
1547 // the GC. Currently, there is no facility on the
1548 // do_full_collection() API to notify the caller than the collection
1549 // did not succeed (e.g., because it was locked out by the GC
1550 // locker). So, right now, we'll ignore the return value.
1551 bool dummy = do_collection(true, /* explicit_gc */
1552 clear_all_soft_refs,
1553 0 /* word_size */);
1554 }
1555
1556 // This code is mostly copied from TenuredGeneration.
1557 void
1558 G1CollectedHeap::
1559 resize_if_necessary_after_full_collection(size_t word_size) {
1560 // Include the current allocation, if any, and bytes that will be
1561 // pre-allocated to support collections, as "used".
1562 const size_t used_after_gc = used();
1563 const size_t capacity_after_gc = capacity();
1564 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1565
1566 // This is enforced in arguments.cpp.
1567 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1568 "otherwise the code below doesn't make sense");
1569
1570 // We don't have floating point command-line arguments
1571 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1572 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1573 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1574 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1575
1576 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1577 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1578
1579 // We have to be careful here as these two calculations can overflow
1580 // 32-bit size_t's.
1581 double used_after_gc_d = (double) used_after_gc;
1582 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1583 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1584
1585 // Let's make sure that they are both under the max heap size, which
1586 // by default will make them fit into a size_t.
1587 double desired_capacity_upper_bound = (double) max_heap_size;
1588 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1589 desired_capacity_upper_bound);
1590 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1591 desired_capacity_upper_bound);
1592
1593 // We can now safely turn them into size_t's.
1594 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1595 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1596
1597 // This assert only makes sense here, before we adjust them
1598 // with respect to the min and max heap size.
1599 assert(minimum_desired_capacity <= maximum_desired_capacity,
1600 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1601 "maximum_desired_capacity = "SIZE_FORMAT,
1602 minimum_desired_capacity, maximum_desired_capacity));
1603
1604 // Should not be greater than the heap max size. No need to adjust
1605 // it with respect to the heap min size as it's a lower bound (i.e.,
1606 // we'll try to make the capacity larger than it, not smaller).
1607 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1608 // Should not be less than the heap min size. No need to adjust it
1609 // with respect to the heap max size as it's an upper bound (i.e.,
1610 // we'll try to make the capacity smaller than it, not greater).
1611 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1612
1613 if (capacity_after_gc < minimum_desired_capacity) {
1614 // Don't expand unless it's significant
1615 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1616 ergo_verbose4(ErgoHeapSizing,
1617 "attempt heap expansion",
1618 ergo_format_reason("capacity lower than "
1619 "min desired capacity after Full GC")
1620 ergo_format_byte("capacity")
1621 ergo_format_byte("occupancy")
1622 ergo_format_byte_perc("min desired capacity"),
1623 capacity_after_gc, used_after_gc,
1624 minimum_desired_capacity, (double) MinHeapFreeRatio);
1625 expand(expand_bytes);
1626
1627 // No expansion, now see if we want to shrink
1628 } else if (capacity_after_gc > maximum_desired_capacity) {
1629 // Capacity too large, compute shrinking size
1630 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1631 ergo_verbose4(ErgoHeapSizing,
1632 "attempt heap shrinking",
1633 ergo_format_reason("capacity higher than "
1634 "max desired capacity after Full GC")
1635 ergo_format_byte("capacity")
1636 ergo_format_byte("occupancy")
1637 ergo_format_byte_perc("max desired capacity"),
1638 capacity_after_gc, used_after_gc,
1639 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1640 shrink(shrink_bytes);
1641 }
1642 }
1643
1644
1645 HeapWord*
1646 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1647 bool* succeeded) {
1648 assert_at_safepoint(true /* should_be_vm_thread */);
1649
1650 *succeeded = true;
1651 // Let's attempt the allocation first.
1652 HeapWord* result =
1653 attempt_allocation_at_safepoint(word_size,
1654 false /* expect_null_mutator_alloc_region */);
1655 if (result != NULL) {
1656 assert(*succeeded, "sanity");
1657 return result;
1658 }
1659
1660 // In a G1 heap, we're supposed to keep allocation from failing by
1661 // incremental pauses. Therefore, at least for now, we'll favor
1662 // expansion over collection. (This might change in the future if we can
1663 // do something smarter than full collection to satisfy a failed alloc.)
1664 result = expand_and_allocate(word_size);
1665 if (result != NULL) {
1666 assert(*succeeded, "sanity");
1667 return result;
1668 }
1669
1670 // Expansion didn't work, we'll try to do a Full GC.
1671 bool gc_succeeded = do_collection(false, /* explicit_gc */
1672 false, /* clear_all_soft_refs */
1673 word_size);
1674 if (!gc_succeeded) {
1675 *succeeded = false;
1676 return NULL;
1677 }
1678
1679 // Retry the allocation
1680 result = attempt_allocation_at_safepoint(word_size,
1681 true /* expect_null_mutator_alloc_region */);
1682 if (result != NULL) {
1683 assert(*succeeded, "sanity");
1684 return result;
1685 }
1686
1687 // Then, try a Full GC that will collect all soft references.
1688 gc_succeeded = do_collection(false, /* explicit_gc */
1689 true, /* clear_all_soft_refs */
1690 word_size);
1691 if (!gc_succeeded) {
1692 *succeeded = false;
1693 return NULL;
1694 }
1695
1696 // Retry the allocation once more
1697 result = attempt_allocation_at_safepoint(word_size,
1698 true /* expect_null_mutator_alloc_region */);
1699 if (result != NULL) {
1700 assert(*succeeded, "sanity");
1701 return result;
1702 }
1703
1704 assert(!collector_policy()->should_clear_all_soft_refs(),
1705 "Flag should have been handled and cleared prior to this point");
1706
1707 // What else? We might try synchronous finalization later. If the total
1708 // space available is large enough for the allocation, then a more
1709 // complete compaction phase than we've tried so far might be
1710 // appropriate.
1711 assert(*succeeded, "sanity");
1712 return NULL;
1713 }
1714
1715 // Attempting to expand the heap sufficiently
1716 // to support an allocation of the given "word_size". If
1717 // successful, perform the allocation and return the address of the
1718 // allocated block, or else "NULL".
1719
1720 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1721 assert_at_safepoint(true /* should_be_vm_thread */);
1722
1723 verify_region_sets_optional();
1724
1725 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1726 ergo_verbose1(ErgoHeapSizing,
1727 "attempt heap expansion",
1728 ergo_format_reason("allocation request failed")
1729 ergo_format_byte("allocation request"),
1730 word_size * HeapWordSize);
1731 if (expand(expand_bytes)) {
1732 _hrs.verify_optional();
1733 verify_region_sets_optional();
1734 return attempt_allocation_at_safepoint(word_size,
1735 false /* expect_null_mutator_alloc_region */);
1736 }
1737 return NULL;
1738 }
1739
1740 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1741 HeapWord* new_end) {
1742 assert(old_end != new_end, "don't call this otherwise");
1743 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1744
1745 // Update the committed mem region.
1746 _g1_committed.set_end(new_end);
1747 // Tell the card table about the update.
1748 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1749 // Tell the BOT about the update.
1750 _bot_shared->resize(_g1_committed.word_size());
1751 // Tell the hot card cache about the update
1752 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1753 }
1754
1755 bool G1CollectedHeap::expand(size_t expand_bytes) {
1756 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1757 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1758 HeapRegion::GrainBytes);
1759 ergo_verbose2(ErgoHeapSizing,
1760 "expand the heap",
1761 ergo_format_byte("requested expansion amount")
1762 ergo_format_byte("attempted expansion amount"),
1763 expand_bytes, aligned_expand_bytes);
1764
1765 if (_g1_storage.uncommitted_size() == 0) {
1766 ergo_verbose0(ErgoHeapSizing,
1767 "did not expand the heap",
1768 ergo_format_reason("heap already fully expanded"));
1769 return false;
1770 }
1771
1772 // First commit the memory.
1773 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1774 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1775 if (successful) {
1776 // Then propagate this update to the necessary data structures.
1777 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1778 update_committed_space(old_end, new_end);
1779
1780 FreeRegionList expansion_list("Local Expansion List");
1781 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1782 assert(mr.start() == old_end, "post-condition");
1783 // mr might be a smaller region than what was requested if
1784 // expand_by() was unable to allocate the HeapRegion instances
1785 assert(mr.end() <= new_end, "post-condition");
1786
1787 size_t actual_expand_bytes = mr.byte_size();
1788 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1789 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1790 "post-condition");
1791 if (actual_expand_bytes < aligned_expand_bytes) {
1792 // We could not expand _hrs to the desired size. In this case we
1793 // need to shrink the committed space accordingly.
1794 assert(mr.end() < new_end, "invariant");
1795
1796 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1797 // First uncommit the memory.
1798 _g1_storage.shrink_by(diff_bytes);
1799 // Then propagate this update to the necessary data structures.
1800 update_committed_space(new_end, mr.end());
1801 }
1802 _free_list.add_as_tail(&expansion_list);
1803
1804 if (_hr_printer.is_active()) {
1805 HeapWord* curr = mr.start();
1806 while (curr < mr.end()) {
1807 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1808 _hr_printer.commit(curr, curr_end);
1809 curr = curr_end;
1810 }
1811 assert(curr == mr.end(), "post-condition");
1812 }
1813 g1_policy()->record_new_heap_size(n_regions());
1814 } else {
1815 ergo_verbose0(ErgoHeapSizing,
1816 "did not expand the heap",
1817 ergo_format_reason("heap expansion operation failed"));
1818 // The expansion of the virtual storage space was unsuccessful.
1819 // Let's see if it was because we ran out of swap.
1820 if (G1ExitOnExpansionFailure &&
1821 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1822 // We had head room...
1823 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1824 }
1825 }
1826 return successful;
1827 }
1828
1829 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1830 size_t aligned_shrink_bytes =
1831 ReservedSpace::page_align_size_down(shrink_bytes);
1832 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1833 HeapRegion::GrainBytes);
1834 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1835
1836 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1837 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1838 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1839
1840 ergo_verbose3(ErgoHeapSizing,
1841 "shrink the heap",
1842 ergo_format_byte("requested shrinking amount")
1843 ergo_format_byte("aligned shrinking amount")
1844 ergo_format_byte("attempted shrinking amount"),
1845 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1846 if (num_regions_removed > 0) {
1847 _g1_storage.shrink_by(shrunk_bytes);
1848 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1849
1850 if (_hr_printer.is_active()) {
1851 HeapWord* curr = old_end;
1852 while (curr > new_end) {
1853 HeapWord* curr_end = curr;
1854 curr -= HeapRegion::GrainWords;
1855 _hr_printer.uncommit(curr, curr_end);
1856 }
1857 }
1858
1859 _expansion_regions += num_regions_removed;
1860 update_committed_space(old_end, new_end);
1861 HeapRegionRemSet::shrink_heap(n_regions());
1862 g1_policy()->record_new_heap_size(n_regions());
1863 } else {
1864 ergo_verbose0(ErgoHeapSizing,
1865 "did not shrink the heap",
1866 ergo_format_reason("heap shrinking operation failed"));
1867 }
1868 }
1869
1870 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1871 verify_region_sets_optional();
1872
1873 // We should only reach here at the end of a Full GC which means we
1874 // should not not be holding to any GC alloc regions. The method
1875 // below will make sure of that and do any remaining clean up.
1876 abandon_gc_alloc_regions();
1877
1878 // Instead of tearing down / rebuilding the free lists here, we
1879 // could instead use the remove_all_pending() method on free_list to
1880 // remove only the ones that we need to remove.
1881 tear_down_region_sets(true /* free_list_only */);
1882 shrink_helper(shrink_bytes);
1883 rebuild_region_sets(true /* free_list_only */);
1884
1885 _hrs.verify_optional();
1886 verify_region_sets_optional();
1887 }
1888
1889 // Public methods.
1890
1891 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1892 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1893 #endif // _MSC_VER
1894
1895
1896 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1897 SharedHeap(policy_),
1898 _g1_policy(policy_),
1899 _dirty_card_queue_set(false),
1900 _into_cset_dirty_card_queue_set(false),
1901 _is_alive_closure_cm(this),
1902 _is_alive_closure_stw(this),
1903 _ref_processor_cm(NULL),
1904 _ref_processor_stw(NULL),
1905 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1906 _bot_shared(NULL),
1907 _evac_failure_scan_stack(NULL),
1908 _mark_in_progress(false),
1909 _cg1r(NULL), _summary_bytes_used(0),
1910 _g1mm(NULL),
1911 _refine_cte_cl(NULL),
1912 _full_collection(false),
1913 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1914 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1915 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1916 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1917 _free_regions_coming(false),
1918 _young_list(new YoungList(this)),
1919 _gc_time_stamp(0),
1920 _retained_old_gc_alloc_region(NULL),
1921 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1922 _old_plab_stats(OldPLABSize, PLABWeight),
1923 _expand_heap_after_alloc_failure(true),
1924 _surviving_young_words(NULL),
1925 _old_marking_cycles_started(0),
1926 _old_marking_cycles_completed(0),
1927 _concurrent_cycle_started(false),
1928 _in_cset_fast_test(),
1929 _dirty_cards_region_list(NULL),
1930 _worker_cset_start_region(NULL),
1931 _worker_cset_start_region_time_stamp(NULL),
1932 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1933 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1934 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1935 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1936
1937 _g1h = this;
1938 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1939 vm_exit_during_initialization("Failed necessary allocation.");
1940 }
1941
1942 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1943
1944 int n_queues = MAX2((int)ParallelGCThreads, 1);
1945 _task_queues = new RefToScanQueueSet(n_queues);
1946
1947 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1948 assert(n_rem_sets > 0, "Invariant.");
1949
1950 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1951 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1952 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1953
1954 for (int i = 0; i < n_queues; i++) {
1955 RefToScanQueue* q = new RefToScanQueue();
1956 q->initialize();
1957 _task_queues->register_queue(i, q);
1958 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1959 }
1960 clear_cset_start_regions();
1961
1962 // Initialize the G1EvacuationFailureALot counters and flags.
1963 NOT_PRODUCT(reset_evacuation_should_fail();)
1964
1965 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1966 }
1967
1968 jint G1CollectedHeap::initialize() {
1969 CollectedHeap::pre_initialize();
1970 os::enable_vtime();
1971
1972 G1Log::init();
1973
1974 // Necessary to satisfy locking discipline assertions.
1975
1976 MutexLocker x(Heap_lock);
1977
1978 // We have to initialize the printer before committing the heap, as
1979 // it will be used then.
1980 _hr_printer.set_active(G1PrintHeapRegions);
1981
1982 // While there are no constraints in the GC code that HeapWordSize
1983 // be any particular value, there are multiple other areas in the
1984 // system which believe this to be true (e.g. oop->object_size in some
1985 // cases incorrectly returns the size in wordSize units rather than
1986 // HeapWordSize).
1987 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1988
1989 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1990 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1991 size_t heap_alignment = collector_policy()->heap_alignment();
1992
1993 // Ensure that the sizes are properly aligned.
1994 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1995 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1996 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1997
1998 _refine_cte_cl = new RefineCardTableEntryClosure();
1999
2000 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2001
2002 // Reserve the maximum.
2003
2004 // When compressed oops are enabled, the preferred heap base
2005 // is calculated by subtracting the requested size from the
2006 // 32Gb boundary and using the result as the base address for
2007 // heap reservation. If the requested size is not aligned to
2008 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2009 // into the ReservedHeapSpace constructor) then the actual
2010 // base of the reserved heap may end up differing from the
2011 // address that was requested (i.e. the preferred heap base).
2012 // If this happens then we could end up using a non-optimal
2013 // compressed oops mode.
2014
2015 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2016 heap_alignment);
2017
2018 // It is important to do this in a way such that concurrent readers can't
2019 // temporarily think something is in the heap. (I've actually seen this
2020 // happen in asserts: DLD.)
2021 _reserved.set_word_size(0);
2022 _reserved.set_start((HeapWord*)heap_rs.base());
2023 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2024
2025 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2026
2027 // Create the gen rem set (and barrier set) for the entire reserved region.
2028 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2029 set_barrier_set(rem_set()->bs());
2030 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2031 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2032 return JNI_ENOMEM;
2033 }
2034
2035 // Also create a G1 rem set.
2036 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2037
2038 // Carve out the G1 part of the heap.
2039
2040 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2041 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2042 g1_rs.size()/HeapWordSize);
2043
2044 _g1_storage.initialize(g1_rs, 0);
2045 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2046 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2047 (HeapWord*) _g1_reserved.end());
2048 assert(_hrs.max_length() == _expansion_regions,
2049 err_msg("max length: %u expansion regions: %u",
2050 _hrs.max_length(), _expansion_regions));
2051
2052 // Do later initialization work for concurrent refinement.
2053 _cg1r->init();
2054
2055 // 6843694 - ensure that the maximum region index can fit
2056 // in the remembered set structures.
2057 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2058 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2059
2060 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2061 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2062 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2063 "too many cards per region");
2064
2065 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2066
2067 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2068 heap_word_size(init_byte_size));
2069
2070 _g1h = this;
2071
2072 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2073
2074 // Create the ConcurrentMark data structure and thread.
2075 // (Must do this late, so that "max_regions" is defined.)
2076 _cm = new ConcurrentMark(this, heap_rs);
2077 if (_cm == NULL || !_cm->completed_initialization()) {
2078 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2079 return JNI_ENOMEM;
2080 }
2081 _cmThread = _cm->cmThread();
2082
2083 // Initialize the from_card cache structure of HeapRegionRemSet.
2084 HeapRegionRemSet::init_heap(max_regions());
2085
2086 // Now expand into the initial heap size.
2087 if (!expand(init_byte_size)) {
2088 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2089 return JNI_ENOMEM;
2090 }
2091
2092 // Perform any initialization actions delegated to the policy.
2093 g1_policy()->init();
2094
2095 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2096 SATB_Q_FL_lock,
2097 G1SATBProcessCompletedThreshold,
2098 Shared_SATB_Q_lock);
2099
2100 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2101 DirtyCardQ_CBL_mon,
2102 DirtyCardQ_FL_lock,
2103 concurrent_g1_refine()->yellow_zone(),
2104 concurrent_g1_refine()->red_zone(),
2105 Shared_DirtyCardQ_lock);
2106
2107 if (G1DeferredRSUpdate) {
2108 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2109 DirtyCardQ_CBL_mon,
2110 DirtyCardQ_FL_lock,
2111 -1, // never trigger processing
2112 -1, // no limit on length
2113 Shared_DirtyCardQ_lock,
2114 &JavaThread::dirty_card_queue_set());
2115 }
2116
2117 // Initialize the card queue set used to hold cards containing
2118 // references into the collection set.
2119 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2120 DirtyCardQ_CBL_mon,
2121 DirtyCardQ_FL_lock,
2122 -1, // never trigger processing
2123 -1, // no limit on length
2124 Shared_DirtyCardQ_lock,
2125 &JavaThread::dirty_card_queue_set());
2126
2127 // In case we're keeping closure specialization stats, initialize those
2128 // counts and that mechanism.
2129 SpecializationStats::clear();
2130
2131 // Here we allocate the dummy full region that is required by the
2132 // G1AllocRegion class. If we don't pass an address in the reserved
2133 // space here, lots of asserts fire.
2134
2135 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2136 _g1_reserved.start());
2137 // We'll re-use the same region whether the alloc region will
2138 // require BOT updates or not and, if it doesn't, then a non-young
2139 // region will complain that it cannot support allocations without
2140 // BOT updates. So we'll tag the dummy region as young to avoid that.
2141 dummy_region->set_young();
2142 // Make sure it's full.
2143 dummy_region->set_top(dummy_region->end());
2144 G1AllocRegion::setup(this, dummy_region);
2145
2146 init_mutator_alloc_region();
2147
2148 // Do create of the monitoring and management support so that
2149 // values in the heap have been properly initialized.
2150 _g1mm = new G1MonitoringSupport(this);
2151
2152 G1StringDedup::initialize();
2153
2154 return JNI_OK;
2155 }
2156
2157 void G1CollectedHeap::stop() {
2158 // Stop all concurrent threads. We do this to make sure these threads
2159 // do not continue to execute and access resources (e.g. gclog_or_tty)
2160 // that are destroyed during shutdown.
2161 _cg1r->stop();
2162 _cmThread->stop();
2163 if (G1StringDedup::is_enabled()) {
2164 G1StringDedup::stop();
2165 }
2166 }
2167
2168 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2169 return HeapRegion::max_region_size();
2170 }
2171
2172 void G1CollectedHeap::ref_processing_init() {
2173 // Reference processing in G1 currently works as follows:
2174 //
2175 // * There are two reference processor instances. One is
2176 // used to record and process discovered references
2177 // during concurrent marking; the other is used to
2178 // record and process references during STW pauses
2179 // (both full and incremental).
2180 // * Both ref processors need to 'span' the entire heap as
2181 // the regions in the collection set may be dotted around.
2182 //
2183 // * For the concurrent marking ref processor:
2184 // * Reference discovery is enabled at initial marking.
2185 // * Reference discovery is disabled and the discovered
2186 // references processed etc during remarking.
2187 // * Reference discovery is MT (see below).
2188 // * Reference discovery requires a barrier (see below).
2189 // * Reference processing may or may not be MT
2190 // (depending on the value of ParallelRefProcEnabled
2191 // and ParallelGCThreads).
2192 // * A full GC disables reference discovery by the CM
2193 // ref processor and abandons any entries on it's
2194 // discovered lists.
2195 //
2196 // * For the STW processor:
2197 // * Non MT discovery is enabled at the start of a full GC.
2198 // * Processing and enqueueing during a full GC is non-MT.
2199 // * During a full GC, references are processed after marking.
2200 //
2201 // * Discovery (may or may not be MT) is enabled at the start
2202 // of an incremental evacuation pause.
2203 // * References are processed near the end of a STW evacuation pause.
2204 // * For both types of GC:
2205 // * Discovery is atomic - i.e. not concurrent.
2206 // * Reference discovery will not need a barrier.
2207
2208 SharedHeap::ref_processing_init();
2209 MemRegion mr = reserved_region();
2210
2211 // Concurrent Mark ref processor
2212 _ref_processor_cm =
2213 new ReferenceProcessor(mr, // span
2214 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2215 // mt processing
2216 (int) ParallelGCThreads,
2217 // degree of mt processing
2218 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2219 // mt discovery
2220 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2221 // degree of mt discovery
2222 false,
2223 // Reference discovery is not atomic
2224 &_is_alive_closure_cm);
2225 // is alive closure
2226 // (for efficiency/performance)
2227
2228 // STW ref processor
2229 _ref_processor_stw =
2230 new ReferenceProcessor(mr, // span
2231 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2232 // mt processing
2233 MAX2((int)ParallelGCThreads, 1),
2234 // degree of mt processing
2235 (ParallelGCThreads > 1),
2236 // mt discovery
2237 MAX2((int)ParallelGCThreads, 1),
2238 // degree of mt discovery
2239 true,
2240 // Reference discovery is atomic
2241 &_is_alive_closure_stw);
2242 // is alive closure
2243 // (for efficiency/performance)
2244 }
2245
2246 size_t G1CollectedHeap::capacity() const {
2247 return _g1_committed.byte_size();
2248 }
2249
2250 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2251 assert(!hr->continuesHumongous(), "pre-condition");
2252 hr->reset_gc_time_stamp();
2253 if (hr->startsHumongous()) {
2254 uint first_index = hr->hrs_index() + 1;
2255 uint last_index = hr->last_hc_index();
2256 for (uint i = first_index; i < last_index; i += 1) {
2257 HeapRegion* chr = region_at(i);
2258 assert(chr->continuesHumongous(), "sanity");
2259 chr->reset_gc_time_stamp();
2260 }
2261 }
2262 }
2263
2264 #ifndef PRODUCT
2265 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2266 private:
2267 unsigned _gc_time_stamp;
2268 bool _failures;
2269
2270 public:
2271 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2272 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2273
2274 virtual bool doHeapRegion(HeapRegion* hr) {
2275 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2276 if (_gc_time_stamp != region_gc_time_stamp) {
2277 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2278 "expected %d", HR_FORMAT_PARAMS(hr),
2279 region_gc_time_stamp, _gc_time_stamp);
2280 _failures = true;
2281 }
2282 return false;
2283 }
2284
2285 bool failures() { return _failures; }
2286 };
2287
2288 void G1CollectedHeap::check_gc_time_stamps() {
2289 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2290 heap_region_iterate(&cl);
2291 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2292 }
2293 #endif // PRODUCT
2294
2295 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2296 DirtyCardQueue* into_cset_dcq,
2297 bool concurrent,
2298 uint worker_i) {
2299 // Clean cards in the hot card cache
2300 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2301 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2302
2303 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2304 int n_completed_buffers = 0;
2305 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2306 n_completed_buffers++;
2307 }
2308 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2309 dcqs.clear_n_completed_buffers();
2310 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2311 }
2312
2313
2314 // Computes the sum of the storage used by the various regions.
2315
2316 size_t G1CollectedHeap::used() const {
2317 assert(Heap_lock->owner() != NULL,
2318 "Should be owned on this thread's behalf.");
2319 size_t result = _summary_bytes_used;
2320 // Read only once in case it is set to NULL concurrently
2321 HeapRegion* hr = _mutator_alloc_region.get();
2322 if (hr != NULL)
2323 result += hr->used();
2324 return result;
2325 }
2326
2327 size_t G1CollectedHeap::used_unlocked() const {
2328 size_t result = _summary_bytes_used;
2329 return result;
2330 }
2331
2332 class SumUsedClosure: public HeapRegionClosure {
2333 size_t _used;
2334 public:
2335 SumUsedClosure() : _used(0) {}
2336 bool doHeapRegion(HeapRegion* r) {
2337 if (!r->continuesHumongous()) {
2338 _used += r->used();
2339 }
2340 return false;
2341 }
2342 size_t result() { return _used; }
2343 };
2344
2345 size_t G1CollectedHeap::recalculate_used() const {
2346 double recalculate_used_start = os::elapsedTime();
2347
2348 SumUsedClosure blk;
2349 heap_region_iterate(&blk);
2350
2351 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2352 return blk.result();
2353 }
2354
2355 size_t G1CollectedHeap::unsafe_max_alloc() {
2356 if (free_regions() > 0) return HeapRegion::GrainBytes;
2357 // otherwise, is there space in the current allocation region?
2358
2359 // We need to store the current allocation region in a local variable
2360 // here. The problem is that this method doesn't take any locks and
2361 // there may be other threads which overwrite the current allocation
2362 // region field. attempt_allocation(), for example, sets it to NULL
2363 // and this can happen *after* the NULL check here but before the call
2364 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2365 // to be a problem in the optimized build, since the two loads of the
2366 // current allocation region field are optimized away.
2367 HeapRegion* hr = _mutator_alloc_region.get();
2368 if (hr == NULL) {
2369 return 0;
2370 }
2371 return hr->free();
2372 }
2373
2374 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2375 switch (cause) {
2376 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2377 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2378 case GCCause::_g1_humongous_allocation: return true;
2379 default: return false;
2380 }
2381 }
2382
2383 #ifndef PRODUCT
2384 void G1CollectedHeap::allocate_dummy_regions() {
2385 // Let's fill up most of the region
2386 size_t word_size = HeapRegion::GrainWords - 1024;
2387 // And as a result the region we'll allocate will be humongous.
2388 guarantee(isHumongous(word_size), "sanity");
2389
2390 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2391 // Let's use the existing mechanism for the allocation
2392 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2393 if (dummy_obj != NULL) {
2394 MemRegion mr(dummy_obj, word_size);
2395 CollectedHeap::fill_with_object(mr);
2396 } else {
2397 // If we can't allocate once, we probably cannot allocate
2398 // again. Let's get out of the loop.
2399 break;
2400 }
2401 }
2402 }
2403 #endif // !PRODUCT
2404
2405 void G1CollectedHeap::increment_old_marking_cycles_started() {
2406 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2407 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2408 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2409 _old_marking_cycles_started, _old_marking_cycles_completed));
2410
2411 _old_marking_cycles_started++;
2412 }
2413
2414 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2415 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2416
2417 // We assume that if concurrent == true, then the caller is a
2418 // concurrent thread that was joined the Suspendible Thread
2419 // Set. If there's ever a cheap way to check this, we should add an
2420 // assert here.
2421
2422 // Given that this method is called at the end of a Full GC or of a
2423 // concurrent cycle, and those can be nested (i.e., a Full GC can
2424 // interrupt a concurrent cycle), the number of full collections
2425 // completed should be either one (in the case where there was no
2426 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2427 // behind the number of full collections started.
2428
2429 // This is the case for the inner caller, i.e. a Full GC.
2430 assert(concurrent ||
2431 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2432 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2433 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2434 "is inconsistent with _old_marking_cycles_completed = %u",
2435 _old_marking_cycles_started, _old_marking_cycles_completed));
2436
2437 // This is the case for the outer caller, i.e. the concurrent cycle.
2438 assert(!concurrent ||
2439 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2440 err_msg("for outer caller (concurrent cycle): "
2441 "_old_marking_cycles_started = %u "
2442 "is inconsistent with _old_marking_cycles_completed = %u",
2443 _old_marking_cycles_started, _old_marking_cycles_completed));
2444
2445 _old_marking_cycles_completed += 1;
2446
2447 // We need to clear the "in_progress" flag in the CM thread before
2448 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2449 // is set) so that if a waiter requests another System.gc() it doesn't
2450 // incorrectly see that a marking cycle is still in progress.
2451 if (concurrent) {
2452 _cmThread->clear_in_progress();
2453 }
2454
2455 // This notify_all() will ensure that a thread that called
2456 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2457 // and it's waiting for a full GC to finish will be woken up. It is
2458 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2459 FullGCCount_lock->notify_all();
2460 }
2461
2462 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2463 _concurrent_cycle_started = true;
2464 _gc_timer_cm->register_gc_start(start_time);
2465
2466 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2467 trace_heap_before_gc(_gc_tracer_cm);
2468 }
2469
2470 void G1CollectedHeap::register_concurrent_cycle_end() {
2471 if (_concurrent_cycle_started) {
2472 if (_cm->has_aborted()) {
2473 _gc_tracer_cm->report_concurrent_mode_failure();
2474 }
2475
2476 _gc_timer_cm->register_gc_end();
2477 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2478
2479 _concurrent_cycle_started = false;
2480 }
2481 }
2482
2483 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2484 if (_concurrent_cycle_started) {
2485 trace_heap_after_gc(_gc_tracer_cm);
2486 }
2487 }
2488
2489 G1YCType G1CollectedHeap::yc_type() {
2490 bool is_young = g1_policy()->gcs_are_young();
2491 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2492 bool is_during_mark = mark_in_progress();
2493
2494 if (is_initial_mark) {
2495 return InitialMark;
2496 } else if (is_during_mark) {
2497 return DuringMark;
2498 } else if (is_young) {
2499 return Normal;
2500 } else {
2501 return Mixed;
2502 }
2503 }
2504
2505 void G1CollectedHeap::collect(GCCause::Cause cause) {
2506 assert_heap_not_locked();
2507
2508 unsigned int gc_count_before;
2509 unsigned int old_marking_count_before;
2510 bool retry_gc;
2511
2512 do {
2513 retry_gc = false;
2514
2515 {
2516 MutexLocker ml(Heap_lock);
2517
2518 // Read the GC count while holding the Heap_lock
2519 gc_count_before = total_collections();
2520 old_marking_count_before = _old_marking_cycles_started;
2521 }
2522
2523 if (should_do_concurrent_full_gc(cause)) {
2524 // Schedule an initial-mark evacuation pause that will start a
2525 // concurrent cycle. We're setting word_size to 0 which means that
2526 // we are not requesting a post-GC allocation.
2527 VM_G1IncCollectionPause op(gc_count_before,
2528 0, /* word_size */
2529 true, /* should_initiate_conc_mark */
2530 g1_policy()->max_pause_time_ms(),
2531 cause);
2532
2533 VMThread::execute(&op);
2534 if (!op.pause_succeeded()) {
2535 if (old_marking_count_before == _old_marking_cycles_started) {
2536 retry_gc = op.should_retry_gc();
2537 } else {
2538 // A Full GC happened while we were trying to schedule the
2539 // initial-mark GC. No point in starting a new cycle given
2540 // that the whole heap was collected anyway.
2541 }
2542
2543 if (retry_gc) {
2544 if (GC_locker::is_active_and_needs_gc()) {
2545 GC_locker::stall_until_clear();
2546 }
2547 }
2548 }
2549 } else {
2550 if (cause == GCCause::_gc_locker
2551 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2552
2553 // Schedule a standard evacuation pause. We're setting word_size
2554 // to 0 which means that we are not requesting a post-GC allocation.
2555 VM_G1IncCollectionPause op(gc_count_before,
2556 0, /* word_size */
2557 false, /* should_initiate_conc_mark */
2558 g1_policy()->max_pause_time_ms(),
2559 cause);
2560 VMThread::execute(&op);
2561 } else {
2562 // Schedule a Full GC.
2563 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2564 VMThread::execute(&op);
2565 }
2566 }
2567 } while (retry_gc);
2568 }
2569
2570 bool G1CollectedHeap::is_in(const void* p) const {
2571 if (_g1_committed.contains(p)) {
2572 // Given that we know that p is in the committed space,
2573 // heap_region_containing_raw() should successfully
2574 // return the containing region.
2575 HeapRegion* hr = heap_region_containing_raw(p);
2576 return hr->is_in(p);
2577 } else {
2578 return false;
2579 }
2580 }
2581
2582 // Iteration functions.
2583
2584 // Iterates an OopClosure over all ref-containing fields of objects
2585 // within a HeapRegion.
2586
2587 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2588 MemRegion _mr;
2589 ExtendedOopClosure* _cl;
2590 public:
2591 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2592 : _mr(mr), _cl(cl) {}
2593 bool doHeapRegion(HeapRegion* r) {
2594 if (!r->continuesHumongous()) {
2595 r->oop_iterate(_cl);
2596 }
2597 return false;
2598 }
2599 };
2600
2601 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2602 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2603 heap_region_iterate(&blk);
2604 }
2605
2606 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2607 IterateOopClosureRegionClosure blk(mr, cl);
2608 heap_region_iterate(&blk);
2609 }
2610
2611 // Iterates an ObjectClosure over all objects within a HeapRegion.
2612
2613 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2614 ObjectClosure* _cl;
2615 public:
2616 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2617 bool doHeapRegion(HeapRegion* r) {
2618 if (! r->continuesHumongous()) {
2619 r->object_iterate(_cl);
2620 }
2621 return false;
2622 }
2623 };
2624
2625 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2626 IterateObjectClosureRegionClosure blk(cl);
2627 heap_region_iterate(&blk);
2628 }
2629
2630 // Calls a SpaceClosure on a HeapRegion.
2631
2632 class SpaceClosureRegionClosure: public HeapRegionClosure {
2633 SpaceClosure* _cl;
2634 public:
2635 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2636 bool doHeapRegion(HeapRegion* r) {
2637 _cl->do_space(r);
2638 return false;
2639 }
2640 };
2641
2642 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2643 SpaceClosureRegionClosure blk(cl);
2644 heap_region_iterate(&blk);
2645 }
2646
2647 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2648 _hrs.iterate(cl);
2649 }
2650
2651 void
2652 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2653 uint worker_id,
2654 uint no_of_par_workers,
2655 jint claim_value) {
2656 const uint regions = n_regions();
2657 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2658 no_of_par_workers :
2659 1);
2660 assert(UseDynamicNumberOfGCThreads ||
2661 no_of_par_workers == workers()->total_workers(),
2662 "Non dynamic should use fixed number of workers");
2663 // try to spread out the starting points of the workers
2664 const HeapRegion* start_hr =
2665 start_region_for_worker(worker_id, no_of_par_workers);
2666 const uint start_index = start_hr->hrs_index();
2667
2668 // each worker will actually look at all regions
2669 for (uint count = 0; count < regions; ++count) {
2670 const uint index = (start_index + count) % regions;
2671 assert(0 <= index && index < regions, "sanity");
2672 HeapRegion* r = region_at(index);
2673 // we'll ignore "continues humongous" regions (we'll process them
2674 // when we come across their corresponding "start humongous"
2675 // region) and regions already claimed
2676 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2677 continue;
2678 }
2679 // OK, try to claim it
2680 if (r->claimHeapRegion(claim_value)) {
2681 // success!
2682 assert(!r->continuesHumongous(), "sanity");
2683 if (r->startsHumongous()) {
2684 // If the region is "starts humongous" we'll iterate over its
2685 // "continues humongous" first; in fact we'll do them
2686 // first. The order is important. In on case, calling the
2687 // closure on the "starts humongous" region might de-allocate
2688 // and clear all its "continues humongous" regions and, as a
2689 // result, we might end up processing them twice. So, we'll do
2690 // them first (notice: most closures will ignore them anyway) and
2691 // then we'll do the "starts humongous" region.
2692 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2693 HeapRegion* chr = region_at(ch_index);
2694
2695 // if the region has already been claimed or it's not
2696 // "continues humongous" we're done
2697 if (chr->claim_value() == claim_value ||
2698 !chr->continuesHumongous()) {
2699 break;
2700 }
2701
2702 // No one should have claimed it directly. We can given
2703 // that we claimed its "starts humongous" region.
2704 assert(chr->claim_value() != claim_value, "sanity");
2705 assert(chr->humongous_start_region() == r, "sanity");
2706
2707 if (chr->claimHeapRegion(claim_value)) {
2708 // we should always be able to claim it; no one else should
2709 // be trying to claim this region
2710
2711 bool res2 = cl->doHeapRegion(chr);
2712 assert(!res2, "Should not abort");
2713
2714 // Right now, this holds (i.e., no closure that actually
2715 // does something with "continues humongous" regions
2716 // clears them). We might have to weaken it in the future,
2717 // but let's leave these two asserts here for extra safety.
2718 assert(chr->continuesHumongous(), "should still be the case");
2719 assert(chr->humongous_start_region() == r, "sanity");
2720 } else {
2721 guarantee(false, "we should not reach here");
2722 }
2723 }
2724 }
2725
2726 assert(!r->continuesHumongous(), "sanity");
2727 bool res = cl->doHeapRegion(r);
2728 assert(!res, "Should not abort");
2729 }
2730 }
2731 }
2732
2733 class ResetClaimValuesClosure: public HeapRegionClosure {
2734 public:
2735 bool doHeapRegion(HeapRegion* r) {
2736 r->set_claim_value(HeapRegion::InitialClaimValue);
2737 return false;
2738 }
2739 };
2740
2741 void G1CollectedHeap::reset_heap_region_claim_values() {
2742 ResetClaimValuesClosure blk;
2743 heap_region_iterate(&blk);
2744 }
2745
2746 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2747 ResetClaimValuesClosure blk;
2748 collection_set_iterate(&blk);
2749 }
2750
2751 #ifdef ASSERT
2752 // This checks whether all regions in the heap have the correct claim
2753 // value. I also piggy-backed on this a check to ensure that the
2754 // humongous_start_region() information on "continues humongous"
2755 // regions is correct.
2756
2757 class CheckClaimValuesClosure : public HeapRegionClosure {
2758 private:
2759 jint _claim_value;
2760 uint _failures;
2761 HeapRegion* _sh_region;
2762
2763 public:
2764 CheckClaimValuesClosure(jint claim_value) :
2765 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2766 bool doHeapRegion(HeapRegion* r) {
2767 if (r->claim_value() != _claim_value) {
2768 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2769 "claim value = %d, should be %d",
2770 HR_FORMAT_PARAMS(r),
2771 r->claim_value(), _claim_value);
2772 ++_failures;
2773 }
2774 if (!r->isHumongous()) {
2775 _sh_region = NULL;
2776 } else if (r->startsHumongous()) {
2777 _sh_region = r;
2778 } else if (r->continuesHumongous()) {
2779 if (r->humongous_start_region() != _sh_region) {
2780 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2781 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2782 HR_FORMAT_PARAMS(r),
2783 r->humongous_start_region(),
2784 _sh_region);
2785 ++_failures;
2786 }
2787 }
2788 return false;
2789 }
2790 uint failures() { return _failures; }
2791 };
2792
2793 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2794 CheckClaimValuesClosure cl(claim_value);
2795 heap_region_iterate(&cl);
2796 return cl.failures() == 0;
2797 }
2798
2799 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2800 private:
2801 jint _claim_value;
2802 uint _failures;
2803
2804 public:
2805 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2806 _claim_value(claim_value), _failures(0) { }
2807
2808 uint failures() { return _failures; }
2809
2810 bool doHeapRegion(HeapRegion* hr) {
2811 assert(hr->in_collection_set(), "how?");
2812 assert(!hr->isHumongous(), "H-region in CSet");
2813 if (hr->claim_value() != _claim_value) {
2814 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2815 "claim value = %d, should be %d",
2816 HR_FORMAT_PARAMS(hr),
2817 hr->claim_value(), _claim_value);
2818 _failures += 1;
2819 }
2820 return false;
2821 }
2822 };
2823
2824 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2825 CheckClaimValuesInCSetHRClosure cl(claim_value);
2826 collection_set_iterate(&cl);
2827 return cl.failures() == 0;
2828 }
2829 #endif // ASSERT
2830
2831 // Clear the cached CSet starting regions and (more importantly)
2832 // the time stamps. Called when we reset the GC time stamp.
2833 void G1CollectedHeap::clear_cset_start_regions() {
2834 assert(_worker_cset_start_region != NULL, "sanity");
2835 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2836
2837 int n_queues = MAX2((int)ParallelGCThreads, 1);
2838 for (int i = 0; i < n_queues; i++) {
2839 _worker_cset_start_region[i] = NULL;
2840 _worker_cset_start_region_time_stamp[i] = 0;
2841 }
2842 }
2843
2844 // Given the id of a worker, obtain or calculate a suitable
2845 // starting region for iterating over the current collection set.
2846 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2847 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2848
2849 HeapRegion* result = NULL;
2850 unsigned gc_time_stamp = get_gc_time_stamp();
2851
2852 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2853 // Cached starting region for current worker was set
2854 // during the current pause - so it's valid.
2855 // Note: the cached starting heap region may be NULL
2856 // (when the collection set is empty).
2857 result = _worker_cset_start_region[worker_i];
2858 assert(result == NULL || result->in_collection_set(), "sanity");
2859 return result;
2860 }
2861
2862 // The cached entry was not valid so let's calculate
2863 // a suitable starting heap region for this worker.
2864
2865 // We want the parallel threads to start their collection
2866 // set iteration at different collection set regions to
2867 // avoid contention.
2868 // If we have:
2869 // n collection set regions
2870 // p threads
2871 // Then thread t will start at region floor ((t * n) / p)
2872
2873 result = g1_policy()->collection_set();
2874 if (G1CollectedHeap::use_parallel_gc_threads()) {
2875 uint cs_size = g1_policy()->cset_region_length();
2876 uint active_workers = workers()->active_workers();
2877 assert(UseDynamicNumberOfGCThreads ||
2878 active_workers == workers()->total_workers(),
2879 "Unless dynamic should use total workers");
2880
2881 uint end_ind = (cs_size * worker_i) / active_workers;
2882 uint start_ind = 0;
2883
2884 if (worker_i > 0 &&
2885 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2886 // Previous workers starting region is valid
2887 // so let's iterate from there
2888 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2889 result = _worker_cset_start_region[worker_i - 1];
2890 }
2891
2892 for (uint i = start_ind; i < end_ind; i++) {
2893 result = result->next_in_collection_set();
2894 }
2895 }
2896
2897 // Note: the calculated starting heap region may be NULL
2898 // (when the collection set is empty).
2899 assert(result == NULL || result->in_collection_set(), "sanity");
2900 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2901 "should be updated only once per pause");
2902 _worker_cset_start_region[worker_i] = result;
2903 OrderAccess::storestore();
2904 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2905 return result;
2906 }
2907
2908 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2909 uint no_of_par_workers) {
2910 uint worker_num =
2911 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2912 assert(UseDynamicNumberOfGCThreads ||
2913 no_of_par_workers == workers()->total_workers(),
2914 "Non dynamic should use fixed number of workers");
2915 const uint start_index = n_regions() * worker_i / worker_num;
2916 return region_at(start_index);
2917 }
2918
2919 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2920 HeapRegion* r = g1_policy()->collection_set();
2921 while (r != NULL) {
2922 HeapRegion* next = r->next_in_collection_set();
2923 if (cl->doHeapRegion(r)) {
2924 cl->incomplete();
2925 return;
2926 }
2927 r = next;
2928 }
2929 }
2930
2931 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2932 HeapRegionClosure *cl) {
2933 if (r == NULL) {
2934 // The CSet is empty so there's nothing to do.
2935 return;
2936 }
2937
2938 assert(r->in_collection_set(),
2939 "Start region must be a member of the collection set.");
2940 HeapRegion* cur = r;
2941 while (cur != NULL) {
2942 HeapRegion* next = cur->next_in_collection_set();
2943 if (cl->doHeapRegion(cur) && false) {
2944 cl->incomplete();
2945 return;
2946 }
2947 cur = next;
2948 }
2949 cur = g1_policy()->collection_set();
2950 while (cur != r) {
2951 HeapRegion* next = cur->next_in_collection_set();
2952 if (cl->doHeapRegion(cur) && false) {
2953 cl->incomplete();
2954 return;
2955 }
2956 cur = next;
2957 }
2958 }
2959
2960 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2961 return n_regions() > 0 ? region_at(0) : NULL;
2962 }
2963
2964
2965 Space* G1CollectedHeap::space_containing(const void* addr) const {
2966 Space* res = heap_region_containing(addr);
2967 return res;
2968 }
2969
2970 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2971 Space* sp = space_containing(addr);
2972 if (sp != NULL) {
2973 return sp->block_start(addr);
2974 }
2975 return NULL;
2976 }
2977
2978 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2979 Space* sp = space_containing(addr);
2980 assert(sp != NULL, "block_size of address outside of heap");
2981 return sp->block_size(addr);
2982 }
2983
2984 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2985 Space* sp = space_containing(addr);
2986 return sp->block_is_obj(addr);
2987 }
2988
2989 bool G1CollectedHeap::supports_tlab_allocation() const {
2990 return true;
2991 }
2992
2993 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2994 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2995 }
2996
2997 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2998 return young_list()->eden_used_bytes();
2999 }
3000
3001 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3002 // must be smaller than the humongous object limit.
3003 size_t G1CollectedHeap::max_tlab_size() const {
3004 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3005 }
3006
3007 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3008 // Return the remaining space in the cur alloc region, but not less than
3009 // the min TLAB size.
3010
3011 // Also, this value can be at most the humongous object threshold,
3012 // since we can't allow tlabs to grow big enough to accommodate
3013 // humongous objects.
3014
3015 HeapRegion* hr = _mutator_alloc_region.get();
3016 size_t max_tlab = max_tlab_size() * wordSize;
3017 if (hr == NULL) {
3018 return max_tlab;
3019 } else {
3020 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3021 }
3022 }
3023
3024 size_t G1CollectedHeap::max_capacity() const {
3025 return _g1_reserved.byte_size();
3026 }
3027
3028 jlong G1CollectedHeap::millis_since_last_gc() {
3029 // assert(false, "NYI");
3030 return 0;
3031 }
3032
3033 void G1CollectedHeap::prepare_for_verify() {
3034 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3035 ensure_parsability(false);
3036 }
3037 g1_rem_set()->prepare_for_verify();
3038 }
3039
3040 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3041 VerifyOption vo) {
3042 switch (vo) {
3043 case VerifyOption_G1UsePrevMarking:
3044 return hr->obj_allocated_since_prev_marking(obj);
3045 case VerifyOption_G1UseNextMarking:
3046 return hr->obj_allocated_since_next_marking(obj);
3047 case VerifyOption_G1UseMarkWord:
3048 return false;
3049 default:
3050 ShouldNotReachHere();
3051 }
3052 return false; // keep some compilers happy
3053 }
3054
3055 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3056 switch (vo) {
3057 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3058 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3059 case VerifyOption_G1UseMarkWord: return NULL;
3060 default: ShouldNotReachHere();
3061 }
3062 return NULL; // keep some compilers happy
3063 }
3064
3065 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3066 switch (vo) {
3067 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3068 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3069 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3070 default: ShouldNotReachHere();
3071 }
3072 return false; // keep some compilers happy
3073 }
3074
3075 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3076 switch (vo) {
3077 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3078 case VerifyOption_G1UseNextMarking: return "NTAMS";
3079 case VerifyOption_G1UseMarkWord: return "NONE";
3080 default: ShouldNotReachHere();
3081 }
3082 return NULL; // keep some compilers happy
3083 }
3084
3085 class VerifyRootsClosure: public OopClosure {
3086 private:
3087 G1CollectedHeap* _g1h;
3088 VerifyOption _vo;
3089 bool _failures;
3090 public:
3091 // _vo == UsePrevMarking -> use "prev" marking information,
3092 // _vo == UseNextMarking -> use "next" marking information,
3093 // _vo == UseMarkWord -> use mark word from object header.
3094 VerifyRootsClosure(VerifyOption vo) :
3095 _g1h(G1CollectedHeap::heap()),
3096 _vo(vo),
3097 _failures(false) { }
3098
3099 bool failures() { return _failures; }
3100
3101 template <class T> void do_oop_nv(T* p) {
3102 T heap_oop = oopDesc::load_heap_oop(p);
3103 if (!oopDesc::is_null(heap_oop)) {
3104 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3105 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3106 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3107 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3108 if (_vo == VerifyOption_G1UseMarkWord) {
3109 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3110 }
3111 obj->print_on(gclog_or_tty);
3112 _failures = true;
3113 }
3114 }
3115 }
3116
3117 void do_oop(oop* p) { do_oop_nv(p); }
3118 void do_oop(narrowOop* p) { do_oop_nv(p); }
3119 };
3120
3121 class G1VerifyCodeRootOopClosure: public OopClosure {
3122 G1CollectedHeap* _g1h;
3123 OopClosure* _root_cl;
3124 nmethod* _nm;
3125 VerifyOption _vo;
3126 bool _failures;
3127
3128 template <class T> void do_oop_work(T* p) {
3129 // First verify that this root is live
3130 _root_cl->do_oop(p);
3131
3132 if (!G1VerifyHeapRegionCodeRoots) {
3133 // We're not verifying the code roots attached to heap region.
3134 return;
3135 }
3136
3137 // Don't check the code roots during marking verification in a full GC
3138 if (_vo == VerifyOption_G1UseMarkWord) {
3139 return;
3140 }
3141
3142 // Now verify that the current nmethod (which contains p) is
3143 // in the code root list of the heap region containing the
3144 // object referenced by p.
3145
3146 T heap_oop = oopDesc::load_heap_oop(p);
3147 if (!oopDesc::is_null(heap_oop)) {
3148 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3149
3150 // Now fetch the region containing the object
3151 HeapRegion* hr = _g1h->heap_region_containing(obj);
3152 HeapRegionRemSet* hrrs = hr->rem_set();
3153 // Verify that the strong code root list for this region
3154 // contains the nmethod
3155 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3156 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3157 "from nmethod "PTR_FORMAT" not in strong "
3158 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3159 p, _nm, hr->bottom(), hr->end());
3160 _failures = true;
3161 }
3162 }
3163 }
3164
3165 public:
3166 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3167 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3168
3169 void do_oop(oop* p) { do_oop_work(p); }
3170 void do_oop(narrowOop* p) { do_oop_work(p); }
3171
3172 void set_nmethod(nmethod* nm) { _nm = nm; }
3173 bool failures() { return _failures; }
3174 };
3175
3176 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3177 G1VerifyCodeRootOopClosure* _oop_cl;
3178
3179 public:
3180 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3181 _oop_cl(oop_cl) {}
3182
3183 void do_code_blob(CodeBlob* cb) {
3184 nmethod* nm = cb->as_nmethod_or_null();
3185 if (nm != NULL) {
3186 _oop_cl->set_nmethod(nm);
3187 nm->oops_do(_oop_cl);
3188 }
3189 }
3190 };
3191
3192 class YoungRefCounterClosure : public OopClosure {
3193 G1CollectedHeap* _g1h;
3194 int _count;
3195 public:
3196 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3197 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3198 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3199
3200 int count() { return _count; }
3201 void reset_count() { _count = 0; };
3202 };
3203
3204 class VerifyKlassClosure: public KlassClosure {
3205 YoungRefCounterClosure _young_ref_counter_closure;
3206 OopClosure *_oop_closure;
3207 public:
3208 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3209 void do_klass(Klass* k) {
3210 k->oops_do(_oop_closure);
3211
3212 _young_ref_counter_closure.reset_count();
3213 k->oops_do(&_young_ref_counter_closure);
3214 if (_young_ref_counter_closure.count() > 0) {
3215 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3216 }
3217 }
3218 };
3219
3220 class VerifyLivenessOopClosure: public OopClosure {
3221 G1CollectedHeap* _g1h;
3222 VerifyOption _vo;
3223 public:
3224 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3225 _g1h(g1h), _vo(vo)
3226 { }
3227 void do_oop(narrowOop *p) { do_oop_work(p); }
3228 void do_oop( oop *p) { do_oop_work(p); }
3229
3230 template <class T> void do_oop_work(T *p) {
3231 oop obj = oopDesc::load_decode_heap_oop(p);
3232 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3233 "Dead object referenced by a not dead object");
3234 }
3235 };
3236
3237 class VerifyObjsInRegionClosure: public ObjectClosure {
3238 private:
3239 G1CollectedHeap* _g1h;
3240 size_t _live_bytes;
3241 HeapRegion *_hr;
3242 VerifyOption _vo;
3243 public:
3244 // _vo == UsePrevMarking -> use "prev" marking information,
3245 // _vo == UseNextMarking -> use "next" marking information,
3246 // _vo == UseMarkWord -> use mark word from object header.
3247 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3248 : _live_bytes(0), _hr(hr), _vo(vo) {
3249 _g1h = G1CollectedHeap::heap();
3250 }
3251 void do_object(oop o) {
3252 VerifyLivenessOopClosure isLive(_g1h, _vo);
3253 assert(o != NULL, "Huh?");
3254 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3255 // If the object is alive according to the mark word,
3256 // then verify that the marking information agrees.
3257 // Note we can't verify the contra-positive of the
3258 // above: if the object is dead (according to the mark
3259 // word), it may not be marked, or may have been marked
3260 // but has since became dead, or may have been allocated
3261 // since the last marking.
3262 if (_vo == VerifyOption_G1UseMarkWord) {
3263 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3264 }
3265
3266 o->oop_iterate_no_header(&isLive);
3267 if (!_hr->obj_allocated_since_prev_marking(o)) {
3268 size_t obj_size = o->size(); // Make sure we don't overflow
3269 _live_bytes += (obj_size * HeapWordSize);
3270 }
3271 }
3272 }
3273 size_t live_bytes() { return _live_bytes; }
3274 };
3275
3276 class PrintObjsInRegionClosure : public ObjectClosure {
3277 HeapRegion *_hr;
3278 G1CollectedHeap *_g1;
3279 public:
3280 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3281 _g1 = G1CollectedHeap::heap();
3282 };
3283
3284 void do_object(oop o) {
3285 if (o != NULL) {
3286 HeapWord *start = (HeapWord *) o;
3287 size_t word_sz = o->size();
3288 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3289 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3290 (void*) o, word_sz,
3291 _g1->isMarkedPrev(o),
3292 _g1->isMarkedNext(o),
3293 _hr->obj_allocated_since_prev_marking(o));
3294 HeapWord *end = start + word_sz;
3295 HeapWord *cur;
3296 int *val;
3297 for (cur = start; cur < end; cur++) {
3298 val = (int *) cur;
3299 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3300 }
3301 }
3302 }
3303 };
3304
3305 class VerifyRegionClosure: public HeapRegionClosure {
3306 private:
3307 bool _par;
3308 VerifyOption _vo;
3309 bool _failures;
3310 public:
3311 // _vo == UsePrevMarking -> use "prev" marking information,
3312 // _vo == UseNextMarking -> use "next" marking information,
3313 // _vo == UseMarkWord -> use mark word from object header.
3314 VerifyRegionClosure(bool par, VerifyOption vo)
3315 : _par(par),
3316 _vo(vo),
3317 _failures(false) {}
3318
3319 bool failures() {
3320 return _failures;
3321 }
3322
3323 bool doHeapRegion(HeapRegion* r) {
3324 if (!r->continuesHumongous()) {
3325 bool failures = false;
3326 r->verify(_vo, &failures);
3327 if (failures) {
3328 _failures = true;
3329 } else {
3330 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3331 r->object_iterate(¬_dead_yet_cl);
3332 if (_vo != VerifyOption_G1UseNextMarking) {
3333 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3334 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3335 "max_live_bytes "SIZE_FORMAT" "
3336 "< calculated "SIZE_FORMAT,
3337 r->bottom(), r->end(),
3338 r->max_live_bytes(),
3339 not_dead_yet_cl.live_bytes());
3340 _failures = true;
3341 }
3342 } else {
3343 // When vo == UseNextMarking we cannot currently do a sanity
3344 // check on the live bytes as the calculation has not been
3345 // finalized yet.
3346 }
3347 }
3348 }
3349 return false; // stop the region iteration if we hit a failure
3350 }
3351 };
3352
3353 // This is the task used for parallel verification of the heap regions
3354
3355 class G1ParVerifyTask: public AbstractGangTask {
3356 private:
3357 G1CollectedHeap* _g1h;
3358 VerifyOption _vo;
3359 bool _failures;
3360
3361 public:
3362 // _vo == UsePrevMarking -> use "prev" marking information,
3363 // _vo == UseNextMarking -> use "next" marking information,
3364 // _vo == UseMarkWord -> use mark word from object header.
3365 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3366 AbstractGangTask("Parallel verify task"),
3367 _g1h(g1h),
3368 _vo(vo),
3369 _failures(false) { }
3370
3371 bool failures() {
3372 return _failures;
3373 }
3374
3375 void work(uint worker_id) {
3376 HandleMark hm;
3377 VerifyRegionClosure blk(true, _vo);
3378 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3379 _g1h->workers()->active_workers(),
3380 HeapRegion::ParVerifyClaimValue);
3381 if (blk.failures()) {
3382 _failures = true;
3383 }
3384 }
3385 };
3386
3387 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3388 if (SafepointSynchronize::is_at_safepoint()) {
3389 assert(Thread::current()->is_VM_thread(),
3390 "Expected to be executed serially by the VM thread at this point");
3391
3392 if (!silent) { gclog_or_tty->print("Roots "); }
3393 VerifyRootsClosure rootsCl(vo);
3394 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3395 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3396 VerifyKlassClosure klassCl(this, &rootsCl);
3397
3398 // We apply the relevant closures to all the oops in the
3399 // system dictionary, the string table and the code cache.
3400 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3401
3402 // Need cleared claim bits for the strong roots processing
3403 ClassLoaderDataGraph::clear_claimed_marks();
3404
3405 process_strong_roots(true, // activate StrongRootsScope
3406 false, // we set "is scavenging" to false,
3407 // so we don't reset the dirty cards.
3408 ScanningOption(so), // roots scanning options
3409 &rootsCl,
3410 &blobsCl,
3411 &klassCl
3412 );
3413
3414 bool failures = rootsCl.failures() || codeRootsCl.failures();
3415
3416 if (vo != VerifyOption_G1UseMarkWord) {
3417 // If we're verifying during a full GC then the region sets
3418 // will have been torn down at the start of the GC. Therefore
3419 // verifying the region sets will fail. So we only verify
3420 // the region sets when not in a full GC.
3421 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3422 verify_region_sets();
3423 }
3424
3425 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3426 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3427 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3428 "sanity check");
3429
3430 G1ParVerifyTask task(this, vo);
3431 assert(UseDynamicNumberOfGCThreads ||
3432 workers()->active_workers() == workers()->total_workers(),
3433 "If not dynamic should be using all the workers");
3434 int n_workers = workers()->active_workers();
3435 set_par_threads(n_workers);
3436 workers()->run_task(&task);
3437 set_par_threads(0);
3438 if (task.failures()) {
3439 failures = true;
3440 }
3441
3442 // Checks that the expected amount of parallel work was done.
3443 // The implication is that n_workers is > 0.
3444 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3445 "sanity check");
3446
3447 reset_heap_region_claim_values();
3448
3449 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3450 "sanity check");
3451 } else {
3452 VerifyRegionClosure blk(false, vo);
3453 heap_region_iterate(&blk);
3454 if (blk.failures()) {
3455 failures = true;
3456 }
3457 }
3458 if (!silent) gclog_or_tty->print("RemSet ");
3459 rem_set()->verify();
3460
3461 if (G1StringDedup::is_enabled()) {
3462 if (!silent) gclog_or_tty->print("StrDedup ");
3463 G1StringDedup::verify();
3464 }
3465
3466 if (failures) {
3467 gclog_or_tty->print_cr("Heap:");
3468 // It helps to have the per-region information in the output to
3469 // help us track down what went wrong. This is why we call
3470 // print_extended_on() instead of print_on().
3471 print_extended_on(gclog_or_tty);
3472 gclog_or_tty->cr();
3473 #ifndef PRODUCT
3474 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3475 concurrent_mark()->print_reachable("at-verification-failure",
3476 vo, false /* all */);
3477 }
3478 #endif
3479 gclog_or_tty->flush();
3480 }
3481 guarantee(!failures, "there should not have been any failures");
3482 } else {
3483 if (!silent) {
3484 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3485 if (G1StringDedup::is_enabled()) {
3486 gclog_or_tty->print(", StrDedup");
3487 }
3488 gclog_or_tty->print(") ");
3489 }
3490 }
3491 }
3492
3493 void G1CollectedHeap::verify(bool silent) {
3494 verify(silent, VerifyOption_G1UsePrevMarking);
3495 }
3496
3497 double G1CollectedHeap::verify(bool guard, const char* msg) {
3498 double verify_time_ms = 0.0;
3499
3500 if (guard && total_collections() >= VerifyGCStartAt) {
3501 double verify_start = os::elapsedTime();
3502 HandleMark hm; // Discard invalid handles created during verification
3503 prepare_for_verify();
3504 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3505 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3506 }
3507
3508 return verify_time_ms;
3509 }
3510
3511 void G1CollectedHeap::verify_before_gc() {
3512 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3513 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3514 }
3515
3516 void G1CollectedHeap::verify_after_gc() {
3517 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3518 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3519 }
3520
3521 class PrintRegionClosure: public HeapRegionClosure {
3522 outputStream* _st;
3523 public:
3524 PrintRegionClosure(outputStream* st) : _st(st) {}
3525 bool doHeapRegion(HeapRegion* r) {
3526 r->print_on(_st);
3527 return false;
3528 }
3529 };
3530
3531 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3532 const HeapRegion* hr,
3533 const VerifyOption vo) const {
3534 switch (vo) {
3535 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3536 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3537 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3538 default: ShouldNotReachHere();
3539 }
3540 return false; // keep some compilers happy
3541 }
3542
3543 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3544 const VerifyOption vo) const {
3545 switch (vo) {
3546 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3547 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3548 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3549 default: ShouldNotReachHere();
3550 }
3551 return false; // keep some compilers happy
3552 }
3553
3554 void G1CollectedHeap::print_on(outputStream* st) const {
3555 st->print(" %-20s", "garbage-first heap");
3556 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3557 capacity()/K, used_unlocked()/K);
3558 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3559 _g1_storage.low_boundary(),
3560 _g1_storage.high(),
3561 _g1_storage.high_boundary());
3562 st->cr();
3563 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3564 uint young_regions = _young_list->length();
3565 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3566 (size_t) young_regions * HeapRegion::GrainBytes / K);
3567 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3568 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3569 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3570 st->cr();
3571 MetaspaceAux::print_on(st);
3572 }
3573
3574 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3575 print_on(st);
3576
3577 // Print the per-region information.
3578 st->cr();
3579 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3580 "HS=humongous(starts), HC=humongous(continues), "
3581 "CS=collection set, F=free, TS=gc time stamp, "
3582 "PTAMS=previous top-at-mark-start, "
3583 "NTAMS=next top-at-mark-start)");
3584 PrintRegionClosure blk(st);
3585 heap_region_iterate(&blk);
3586 }
3587
3588 void G1CollectedHeap::print_on_error(outputStream* st) const {
3589 this->CollectedHeap::print_on_error(st);
3590
3591 if (_cm != NULL) {
3592 st->cr();
3593 _cm->print_on_error(st);
3594 }
3595 }
3596
3597 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3598 if (G1CollectedHeap::use_parallel_gc_threads()) {
3599 workers()->print_worker_threads_on(st);
3600 }
3601 _cmThread->print_on(st);
3602 st->cr();
3603 _cm->print_worker_threads_on(st);
3604 _cg1r->print_worker_threads_on(st);
3605 if (G1StringDedup::is_enabled()) {
3606 G1StringDedup::print_worker_threads_on(st);
3607 }
3608 }
3609
3610 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3611 if (G1CollectedHeap::use_parallel_gc_threads()) {
3612 workers()->threads_do(tc);
3613 }
3614 tc->do_thread(_cmThread);
3615 _cg1r->threads_do(tc);
3616 if (G1StringDedup::is_enabled()) {
3617 G1StringDedup::threads_do(tc);
3618 }
3619 }
3620
3621 void G1CollectedHeap::print_tracing_info() const {
3622 // We'll overload this to mean "trace GC pause statistics."
3623 if (TraceGen0Time || TraceGen1Time) {
3624 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3625 // to that.
3626 g1_policy()->print_tracing_info();
3627 }
3628 if (G1SummarizeRSetStats) {
3629 g1_rem_set()->print_summary_info();
3630 }
3631 if (G1SummarizeConcMark) {
3632 concurrent_mark()->print_summary_info();
3633 }
3634 g1_policy()->print_yg_surv_rate_info();
3635 SpecializationStats::print();
3636 }
3637
3638 #ifndef PRODUCT
3639 // Helpful for debugging RSet issues.
3640
3641 class PrintRSetsClosure : public HeapRegionClosure {
3642 private:
3643 const char* _msg;
3644 size_t _occupied_sum;
3645
3646 public:
3647 bool doHeapRegion(HeapRegion* r) {
3648 HeapRegionRemSet* hrrs = r->rem_set();
3649 size_t occupied = hrrs->occupied();
3650 _occupied_sum += occupied;
3651
3652 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3653 HR_FORMAT_PARAMS(r));
3654 if (occupied == 0) {
3655 gclog_or_tty->print_cr(" RSet is empty");
3656 } else {
3657 hrrs->print();
3658 }
3659 gclog_or_tty->print_cr("----------");
3660 return false;
3661 }
3662
3663 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3664 gclog_or_tty->cr();
3665 gclog_or_tty->print_cr("========================================");
3666 gclog_or_tty->print_cr("%s", msg);
3667 gclog_or_tty->cr();
3668 }
3669
3670 ~PrintRSetsClosure() {
3671 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3672 gclog_or_tty->print_cr("========================================");
3673 gclog_or_tty->cr();
3674 }
3675 };
3676
3677 void G1CollectedHeap::print_cset_rsets() {
3678 PrintRSetsClosure cl("Printing CSet RSets");
3679 collection_set_iterate(&cl);
3680 }
3681
3682 void G1CollectedHeap::print_all_rsets() {
3683 PrintRSetsClosure cl("Printing All RSets");;
3684 heap_region_iterate(&cl);
3685 }
3686 #endif // PRODUCT
3687
3688 G1CollectedHeap* G1CollectedHeap::heap() {
3689 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3690 "not a garbage-first heap");
3691 return _g1h;
3692 }
3693
3694 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3695 // always_do_update_barrier = false;
3696 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3697 // Fill TLAB's and such
3698 accumulate_statistics_all_tlabs();
3699 ensure_parsability(true);
3700
3701 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3702 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3703 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3704 }
3705 }
3706
3707 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3708
3709 if (G1SummarizeRSetStats &&
3710 (G1SummarizeRSetStatsPeriod > 0) &&
3711 // we are at the end of the GC. Total collections has already been increased.
3712 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3713 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3714 }
3715
3716 // FIXME: what is this about?
3717 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3718 // is set.
3719 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3720 "derived pointer present"));
3721 // always_do_update_barrier = true;
3722
3723 resize_all_tlabs();
3724
3725 // We have just completed a GC. Update the soft reference
3726 // policy with the new heap occupancy
3727 Universe::update_heap_info_at_gc();
3728 }
3729
3730 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3731 unsigned int gc_count_before,
3732 bool* succeeded,
3733 GCCause::Cause gc_cause) {
3734 assert_heap_not_locked_and_not_at_safepoint();
3735 g1_policy()->record_stop_world_start();
3736 VM_G1IncCollectionPause op(gc_count_before,
3737 word_size,
3738 false, /* should_initiate_conc_mark */
3739 g1_policy()->max_pause_time_ms(),
3740 gc_cause);
3741 VMThread::execute(&op);
3742
3743 HeapWord* result = op.result();
3744 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3745 assert(result == NULL || ret_succeeded,
3746 "the result should be NULL if the VM did not succeed");
3747 *succeeded = ret_succeeded;
3748
3749 assert_heap_not_locked();
3750 return result;
3751 }
3752
3753 void
3754 G1CollectedHeap::doConcurrentMark() {
3755 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3756 if (!_cmThread->in_progress()) {
3757 _cmThread->set_started();
3758 CGC_lock->notify();
3759 }
3760 }
3761
3762 size_t G1CollectedHeap::pending_card_num() {
3763 size_t extra_cards = 0;
3764 JavaThread *curr = Threads::first();
3765 while (curr != NULL) {
3766 DirtyCardQueue& dcq = curr->dirty_card_queue();
3767 extra_cards += dcq.size();
3768 curr = curr->next();
3769 }
3770 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3771 size_t buffer_size = dcqs.buffer_size();
3772 size_t buffer_num = dcqs.completed_buffers_num();
3773
3774 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3775 // in bytes - not the number of 'entries'. We need to convert
3776 // into a number of cards.
3777 return (buffer_size * buffer_num + extra_cards) / oopSize;
3778 }
3779
3780 size_t G1CollectedHeap::cards_scanned() {
3781 return g1_rem_set()->cardsScanned();
3782 }
3783
3784 void
3785 G1CollectedHeap::setup_surviving_young_words() {
3786 assert(_surviving_young_words == NULL, "pre-condition");
3787 uint array_length = g1_policy()->young_cset_region_length();
3788 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3789 if (_surviving_young_words == NULL) {
3790 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3791 "Not enough space for young surv words summary.");
3792 }
3793 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3794 #ifdef ASSERT
3795 for (uint i = 0; i < array_length; ++i) {
3796 assert( _surviving_young_words[i] == 0, "memset above" );
3797 }
3798 #endif // !ASSERT
3799 }
3800
3801 void
3802 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3803 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3804 uint array_length = g1_policy()->young_cset_region_length();
3805 for (uint i = 0; i < array_length; ++i) {
3806 _surviving_young_words[i] += surv_young_words[i];
3807 }
3808 }
3809
3810 void
3811 G1CollectedHeap::cleanup_surviving_young_words() {
3812 guarantee( _surviving_young_words != NULL, "pre-condition" );
3813 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3814 _surviving_young_words = NULL;
3815 }
3816
3817 #ifdef ASSERT
3818 class VerifyCSetClosure: public HeapRegionClosure {
3819 public:
3820 bool doHeapRegion(HeapRegion* hr) {
3821 // Here we check that the CSet region's RSet is ready for parallel
3822 // iteration. The fields that we'll verify are only manipulated
3823 // when the region is part of a CSet and is collected. Afterwards,
3824 // we reset these fields when we clear the region's RSet (when the
3825 // region is freed) so they are ready when the region is
3826 // re-allocated. The only exception to this is if there's an
3827 // evacuation failure and instead of freeing the region we leave
3828 // it in the heap. In that case, we reset these fields during
3829 // evacuation failure handling.
3830 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3831
3832 // Here's a good place to add any other checks we'd like to
3833 // perform on CSet regions.
3834 return false;
3835 }
3836 };
3837 #endif // ASSERT
3838
3839 #if TASKQUEUE_STATS
3840 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3841 st->print_raw_cr("GC Task Stats");
3842 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3843 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3844 }
3845
3846 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3847 print_taskqueue_stats_hdr(st);
3848
3849 TaskQueueStats totals;
3850 const int n = workers() != NULL ? workers()->total_workers() : 1;
3851 for (int i = 0; i < n; ++i) {
3852 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3853 totals += task_queue(i)->stats;
3854 }
3855 st->print_raw("tot "); totals.print(st); st->cr();
3856
3857 DEBUG_ONLY(totals.verify());
3858 }
3859
3860 void G1CollectedHeap::reset_taskqueue_stats() {
3861 const int n = workers() != NULL ? workers()->total_workers() : 1;
3862 for (int i = 0; i < n; ++i) {
3863 task_queue(i)->stats.reset();
3864 }
3865 }
3866 #endif // TASKQUEUE_STATS
3867
3868 void G1CollectedHeap::log_gc_header() {
3869 if (!G1Log::fine()) {
3870 return;
3871 }
3872
3873 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3874
3875 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3876 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3877 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3878
3879 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3880 }
3881
3882 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3883 if (!G1Log::fine()) {
3884 return;
3885 }
3886
3887 if (G1Log::finer()) {
3888 if (evacuation_failed()) {
3889 gclog_or_tty->print(" (to-space exhausted)");
3890 }
3891 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3892 g1_policy()->phase_times()->note_gc_end();
3893 g1_policy()->phase_times()->print(pause_time_sec);
3894 g1_policy()->print_detailed_heap_transition();
3895 } else {
3896 if (evacuation_failed()) {
3897 gclog_or_tty->print("--");
3898 }
3899 g1_policy()->print_heap_transition();
3900 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3901 }
3902 gclog_or_tty->flush();
3903 }
3904
3905 bool
3906 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3907 assert_at_safepoint(true /* should_be_vm_thread */);
3908 guarantee(!is_gc_active(), "collection is not reentrant");
3909
3910 if (GC_locker::check_active_before_gc()) {
3911 return false;
3912 }
3913
3914 _gc_timer_stw->register_gc_start();
3915
3916 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3917
3918 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3919 ResourceMark rm;
3920
3921 print_heap_before_gc();
3922 trace_heap_before_gc(_gc_tracer_stw);
3923
3924 verify_region_sets_optional();
3925 verify_dirty_young_regions();
3926
3927 // This call will decide whether this pause is an initial-mark
3928 // pause. If it is, during_initial_mark_pause() will return true
3929 // for the duration of this pause.
3930 g1_policy()->decide_on_conc_mark_initiation();
3931
3932 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3933 assert(!g1_policy()->during_initial_mark_pause() ||
3934 g1_policy()->gcs_are_young(), "sanity");
3935
3936 // We also do not allow mixed GCs during marking.
3937 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3938
3939 // Record whether this pause is an initial mark. When the current
3940 // thread has completed its logging output and it's safe to signal
3941 // the CM thread, the flag's value in the policy has been reset.
3942 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3943
3944 // Inner scope for scope based logging, timers, and stats collection
3945 {
3946 EvacuationInfo evacuation_info;
3947
3948 if (g1_policy()->during_initial_mark_pause()) {
3949 // We are about to start a marking cycle, so we increment the
3950 // full collection counter.
3951 increment_old_marking_cycles_started();
3952 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3953 }
3954
3955 _gc_tracer_stw->report_yc_type(yc_type());
3956
3957 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3958
3959 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3960 workers()->active_workers() : 1);
3961 double pause_start_sec = os::elapsedTime();
3962 g1_policy()->phase_times()->note_gc_start(active_workers);
3963 log_gc_header();
3964
3965 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3966 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3967
3968 // If the secondary_free_list is not empty, append it to the
3969 // free_list. No need to wait for the cleanup operation to finish;
3970 // the region allocation code will check the secondary_free_list
3971 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3972 // set, skip this step so that the region allocation code has to
3973 // get entries from the secondary_free_list.
3974 if (!G1StressConcRegionFreeing) {
3975 append_secondary_free_list_if_not_empty_with_lock();
3976 }
3977
3978 assert(check_young_list_well_formed(), "young list should be well formed");
3979 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3980 "sanity check");
3981
3982 // Don't dynamically change the number of GC threads this early. A value of
3983 // 0 is used to indicate serial work. When parallel work is done,
3984 // it will be set.
3985
3986 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3987 IsGCActiveMark x;
3988
3989 gc_prologue(false);
3990 increment_total_collections(false /* full gc */);
3991 increment_gc_time_stamp();
3992
3993 verify_before_gc();
3994
3995 COMPILER2_PRESENT(DerivedPointerTable::clear());
3996
3997 // Please see comment in g1CollectedHeap.hpp and
3998 // G1CollectedHeap::ref_processing_init() to see how
3999 // reference processing currently works in G1.
4000
4001 // Enable discovery in the STW reference processor
4002 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4003 true /*verify_no_refs*/);
4004
4005 {
4006 // We want to temporarily turn off discovery by the
4007 // CM ref processor, if necessary, and turn it back on
4008 // on again later if we do. Using a scoped
4009 // NoRefDiscovery object will do this.
4010 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4011
4012 // Forget the current alloc region (we might even choose it to be part
4013 // of the collection set!).
4014 release_mutator_alloc_region();
4015
4016 // We should call this after we retire the mutator alloc
4017 // region(s) so that all the ALLOC / RETIRE events are generated
4018 // before the start GC event.
4019 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4020
4021 // This timing is only used by the ergonomics to handle our pause target.
4022 // It is unclear why this should not include the full pause. We will
4023 // investigate this in CR 7178365.
4024 //
4025 // Preserving the old comment here if that helps the investigation:
4026 //
4027 // The elapsed time induced by the start time below deliberately elides
4028 // the possible verification above.
4029 double sample_start_time_sec = os::elapsedTime();
4030
4031 #if YOUNG_LIST_VERBOSE
4032 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4033 _young_list->print();
4034 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4035 #endif // YOUNG_LIST_VERBOSE
4036
4037 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4038
4039 double scan_wait_start = os::elapsedTime();
4040 // We have to wait until the CM threads finish scanning the
4041 // root regions as it's the only way to ensure that all the
4042 // objects on them have been correctly scanned before we start
4043 // moving them during the GC.
4044 bool waited = _cm->root_regions()->wait_until_scan_finished();
4045 double wait_time_ms = 0.0;
4046 if (waited) {
4047 double scan_wait_end = os::elapsedTime();
4048 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4049 }
4050 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4051
4052 #if YOUNG_LIST_VERBOSE
4053 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4054 _young_list->print();
4055 #endif // YOUNG_LIST_VERBOSE
4056
4057 if (g1_policy()->during_initial_mark_pause()) {
4058 concurrent_mark()->checkpointRootsInitialPre();
4059 }
4060
4061 #if YOUNG_LIST_VERBOSE
4062 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4063 _young_list->print();
4064 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4065 #endif // YOUNG_LIST_VERBOSE
4066
4067 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4068
4069 _cm->note_start_of_gc();
4070 // We should not verify the per-thread SATB buffers given that
4071 // we have not filtered them yet (we'll do so during the
4072 // GC). We also call this after finalize_cset() to
4073 // ensure that the CSet has been finalized.
4074 _cm->verify_no_cset_oops(true /* verify_stacks */,
4075 true /* verify_enqueued_buffers */,
4076 false /* verify_thread_buffers */,
4077 true /* verify_fingers */);
4078
4079 if (_hr_printer.is_active()) {
4080 HeapRegion* hr = g1_policy()->collection_set();
4081 while (hr != NULL) {
4082 G1HRPrinter::RegionType type;
4083 if (!hr->is_young()) {
4084 type = G1HRPrinter::Old;
4085 } else if (hr->is_survivor()) {
4086 type = G1HRPrinter::Survivor;
4087 } else {
4088 type = G1HRPrinter::Eden;
4089 }
4090 _hr_printer.cset(hr);
4091 hr = hr->next_in_collection_set();
4092 }
4093 }
4094
4095 #ifdef ASSERT
4096 VerifyCSetClosure cl;
4097 collection_set_iterate(&cl);
4098 #endif // ASSERT
4099
4100 setup_surviving_young_words();
4101
4102 // Initialize the GC alloc regions.
4103 init_gc_alloc_regions(evacuation_info);
4104
4105 // Actually do the work...
4106 evacuate_collection_set(evacuation_info);
4107
4108 // We do this to mainly verify the per-thread SATB buffers
4109 // (which have been filtered by now) since we didn't verify
4110 // them earlier. No point in re-checking the stacks / enqueued
4111 // buffers given that the CSet has not changed since last time
4112 // we checked.
4113 _cm->verify_no_cset_oops(false /* verify_stacks */,
4114 false /* verify_enqueued_buffers */,
4115 true /* verify_thread_buffers */,
4116 true /* verify_fingers */);
4117
4118 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4119 g1_policy()->clear_collection_set();
4120
4121 cleanup_surviving_young_words();
4122
4123 // Start a new incremental collection set for the next pause.
4124 g1_policy()->start_incremental_cset_building();
4125
4126 clear_cset_fast_test();
4127
4128 _young_list->reset_sampled_info();
4129
4130 // Don't check the whole heap at this point as the
4131 // GC alloc regions from this pause have been tagged
4132 // as survivors and moved on to the survivor list.
4133 // Survivor regions will fail the !is_young() check.
4134 assert(check_young_list_empty(false /* check_heap */),
4135 "young list should be empty");
4136
4137 #if YOUNG_LIST_VERBOSE
4138 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4139 _young_list->print();
4140 #endif // YOUNG_LIST_VERBOSE
4141
4142 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4143 _young_list->first_survivor_region(),
4144 _young_list->last_survivor_region());
4145
4146 _young_list->reset_auxilary_lists();
4147
4148 if (evacuation_failed()) {
4149 _summary_bytes_used = recalculate_used();
4150 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4151 for (uint i = 0; i < n_queues; i++) {
4152 if (_evacuation_failed_info_array[i].has_failed()) {
4153 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4154 }
4155 }
4156 } else {
4157 // The "used" of the the collection set have already been subtracted
4158 // when they were freed. Add in the bytes evacuated.
4159 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4160 }
4161
4162 if (g1_policy()->during_initial_mark_pause()) {
4163 // We have to do this before we notify the CM threads that
4164 // they can start working to make sure that all the
4165 // appropriate initialization is done on the CM object.
4166 concurrent_mark()->checkpointRootsInitialPost();
4167 set_marking_started();
4168 // Note that we don't actually trigger the CM thread at
4169 // this point. We do that later when we're sure that
4170 // the current thread has completed its logging output.
4171 }
4172
4173 allocate_dummy_regions();
4174
4175 #if YOUNG_LIST_VERBOSE
4176 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4177 _young_list->print();
4178 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4179 #endif // YOUNG_LIST_VERBOSE
4180
4181 init_mutator_alloc_region();
4182
4183 {
4184 size_t expand_bytes = g1_policy()->expansion_amount();
4185 if (expand_bytes > 0) {
4186 size_t bytes_before = capacity();
4187 // No need for an ergo verbose message here,
4188 // expansion_amount() does this when it returns a value > 0.
4189 if (!expand(expand_bytes)) {
4190 // We failed to expand the heap so let's verify that
4191 // committed/uncommitted amount match the backing store
4192 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4193 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4194 }
4195 }
4196 }
4197
4198 // We redo the verification but now wrt to the new CSet which
4199 // has just got initialized after the previous CSet was freed.
4200 _cm->verify_no_cset_oops(true /* verify_stacks */,
4201 true /* verify_enqueued_buffers */,
4202 true /* verify_thread_buffers */,
4203 true /* verify_fingers */);
4204 _cm->note_end_of_gc();
4205
4206 // This timing is only used by the ergonomics to handle our pause target.
4207 // It is unclear why this should not include the full pause. We will
4208 // investigate this in CR 7178365.
4209 double sample_end_time_sec = os::elapsedTime();
4210 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4211 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4212
4213 MemoryService::track_memory_usage();
4214
4215 // In prepare_for_verify() below we'll need to scan the deferred
4216 // update buffers to bring the RSets up-to-date if
4217 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4218 // the update buffers we'll probably need to scan cards on the
4219 // regions we just allocated to (i.e., the GC alloc
4220 // regions). However, during the last GC we called
4221 // set_saved_mark() on all the GC alloc regions, so card
4222 // scanning might skip the [saved_mark_word()...top()] area of
4223 // those regions (i.e., the area we allocated objects into
4224 // during the last GC). But it shouldn't. Given that
4225 // saved_mark_word() is conditional on whether the GC time stamp
4226 // on the region is current or not, by incrementing the GC time
4227 // stamp here we invalidate all the GC time stamps on all the
4228 // regions and saved_mark_word() will simply return top() for
4229 // all the regions. This is a nicer way of ensuring this rather
4230 // than iterating over the regions and fixing them. In fact, the
4231 // GC time stamp increment here also ensures that
4232 // saved_mark_word() will return top() between pauses, i.e.,
4233 // during concurrent refinement. So we don't need the
4234 // is_gc_active() check to decided which top to use when
4235 // scanning cards (see CR 7039627).
4236 increment_gc_time_stamp();
4237
4238 verify_after_gc();
4239
4240 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4241 ref_processor_stw()->verify_no_references_recorded();
4242
4243 // CM reference discovery will be re-enabled if necessary.
4244 }
4245
4246 // We should do this after we potentially expand the heap so
4247 // that all the COMMIT events are generated before the end GC
4248 // event, and after we retire the GC alloc regions so that all
4249 // RETIRE events are generated before the end GC event.
4250 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4251
4252 if (mark_in_progress()) {
4253 concurrent_mark()->update_g1_committed();
4254 }
4255
4256 #ifdef TRACESPINNING
4257 ParallelTaskTerminator::print_termination_counts();
4258 #endif
4259
4260 gc_epilogue(false);
4261 }
4262
4263 // Print the remainder of the GC log output.
4264 log_gc_footer(os::elapsedTime() - pause_start_sec);
4265
4266 // It is not yet to safe to tell the concurrent mark to
4267 // start as we have some optional output below. We don't want the
4268 // output from the concurrent mark thread interfering with this
4269 // logging output either.
4270
4271 _hrs.verify_optional();
4272 verify_region_sets_optional();
4273
4274 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4275 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4276
4277 print_heap_after_gc();
4278 trace_heap_after_gc(_gc_tracer_stw);
4279
4280 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4281 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4282 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4283 // before any GC notifications are raised.
4284 g1mm()->update_sizes();
4285
4286 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4287 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4288 _gc_timer_stw->register_gc_end();
4289 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4290 }
4291 // It should now be safe to tell the concurrent mark thread to start
4292 // without its logging output interfering with the logging output
4293 // that came from the pause.
4294
4295 if (should_start_conc_mark) {
4296 // CAUTION: after the doConcurrentMark() call below,
4297 // the concurrent marking thread(s) could be running
4298 // concurrently with us. Make sure that anything after
4299 // this point does not assume that we are the only GC thread
4300 // running. Note: of course, the actual marking work will
4301 // not start until the safepoint itself is released in
4302 // SuspendibleThreadSet::desynchronize().
4303 doConcurrentMark();
4304 }
4305
4306 return true;
4307 }
4308
4309 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4310 {
4311 size_t gclab_word_size;
4312 switch (purpose) {
4313 case GCAllocForSurvived:
4314 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4315 break;
4316 case GCAllocForTenured:
4317 gclab_word_size = _old_plab_stats.desired_plab_sz();
4318 break;
4319 default:
4320 assert(false, "unknown GCAllocPurpose");
4321 gclab_word_size = _old_plab_stats.desired_plab_sz();
4322 break;
4323 }
4324
4325 // Prevent humongous PLAB sizes for two reasons:
4326 // * PLABs are allocated using a similar paths as oops, but should
4327 // never be in a humongous region
4328 // * Allowing humongous PLABs needlessly churns the region free lists
4329 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4330 }
4331
4332 void G1CollectedHeap::init_mutator_alloc_region() {
4333 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4334 _mutator_alloc_region.init();
4335 }
4336
4337 void G1CollectedHeap::release_mutator_alloc_region() {
4338 _mutator_alloc_region.release();
4339 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4340 }
4341
4342 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4343 assert_at_safepoint(true /* should_be_vm_thread */);
4344
4345 _survivor_gc_alloc_region.init();
4346 _old_gc_alloc_region.init();
4347 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4348 _retained_old_gc_alloc_region = NULL;
4349
4350 // We will discard the current GC alloc region if:
4351 // a) it's in the collection set (it can happen!),
4352 // b) it's already full (no point in using it),
4353 // c) it's empty (this means that it was emptied during
4354 // a cleanup and it should be on the free list now), or
4355 // d) it's humongous (this means that it was emptied
4356 // during a cleanup and was added to the free list, but
4357 // has been subsequently used to allocate a humongous
4358 // object that may be less than the region size).
4359 if (retained_region != NULL &&
4360 !retained_region->in_collection_set() &&
4361 !(retained_region->top() == retained_region->end()) &&
4362 !retained_region->is_empty() &&
4363 !retained_region->isHumongous()) {
4364 retained_region->set_saved_mark();
4365 // The retained region was added to the old region set when it was
4366 // retired. We have to remove it now, since we don't allow regions
4367 // we allocate to in the region sets. We'll re-add it later, when
4368 // it's retired again.
4369 _old_set.remove(retained_region);
4370 bool during_im = g1_policy()->during_initial_mark_pause();
4371 retained_region->note_start_of_copying(during_im);
4372 _old_gc_alloc_region.set(retained_region);
4373 _hr_printer.reuse(retained_region);
4374 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4375 }
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 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4572 : _g1h(g1h),
4573 _refs(g1h->task_queue(queue_num)),
4574 _dcq(&g1h->dirty_card_queue_set()),
4575 _ct_bs(g1h->g1_barrier_set()),
4576 _g1_rem(g1h->g1_rem_set()),
4577 _hash_seed(17), _queue_num(queue_num),
4578 _term_attempts(0),
4579 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4580 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4581 _age_table(false), _scanner(g1h, this, rp),
4582 _strong_roots_time(0), _term_time(0),
4583 _alloc_buffer_waste(0), _undo_waste(0) {
4584 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4585 // we "sacrifice" entry 0 to keep track of surviving bytes for
4586 // non-young regions (where the age is -1)
4587 // We also add a few elements at the beginning and at the end in
4588 // an attempt to eliminate cache contention
4589 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4590 uint array_length = PADDING_ELEM_NUM +
4591 real_length +
4592 PADDING_ELEM_NUM;
4593 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4594 if (_surviving_young_words_base == NULL)
4595 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4596 "Not enough space for young surv histo.");
4597 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4598 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4599
4600 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4601 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4602
4603 _start = os::elapsedTime();
4604 }
4605
4606 void
4607 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4608 {
4609 st->print_raw_cr("GC Termination Stats");
4610 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4611 " ------waste (KiB)------");
4612 st->print_raw_cr("thr ms ms % ms % attempts"
4613 " total alloc undo");
4614 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4615 " ------- ------- -------");
4616 }
4617
4618 void
4619 G1ParScanThreadState::print_termination_stats(int i,
4620 outputStream* const st) const
4621 {
4622 const double elapsed_ms = elapsed_time() * 1000.0;
4623 const double s_roots_ms = strong_roots_time() * 1000.0;
4624 const double term_ms = term_time() * 1000.0;
4625 st->print_cr("%3d %9.2f %9.2f %6.2f "
4626 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4627 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4628 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4629 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4630 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4631 alloc_buffer_waste() * HeapWordSize / K,
4632 undo_waste() * HeapWordSize / K);
4633 }
4634
4635 #ifdef ASSERT
4636 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4637 assert(ref != NULL, "invariant");
4638 assert(UseCompressedOops, "sanity");
4639 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4640 oop p = oopDesc::load_decode_heap_oop(ref);
4641 assert(_g1h->is_in_g1_reserved(p),
4642 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4643 return true;
4644 }
4645
4646 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4647 assert(ref != NULL, "invariant");
4648 if (has_partial_array_mask(ref)) {
4649 // Must be in the collection set--it's already been copied.
4650 oop p = clear_partial_array_mask(ref);
4651 assert(_g1h->obj_in_cs(p),
4652 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4653 } else {
4654 oop p = oopDesc::load_decode_heap_oop(ref);
4655 assert(_g1h->is_in_g1_reserved(p),
4656 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4657 }
4658 return true;
4659 }
4660
4661 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4662 if (ref.is_narrow()) {
4663 return verify_ref((narrowOop*) ref);
4664 } else {
4665 return verify_ref((oop*) ref);
4666 }
4667 }
4668 #endif // ASSERT
4669
4670 void G1ParScanThreadState::trim_queue() {
4671 assert(_evac_failure_cl != NULL, "not set");
4672
4673 StarTask ref;
4674 do {
4675 // Drain the overflow stack first, so other threads can steal.
4676 while (refs()->pop_overflow(ref)) {
4677 deal_with_reference(ref);
4678 }
4679
4680 while (refs()->pop_local(ref)) {
4681 deal_with_reference(ref);
4682 }
4683 } while (!refs()->is_empty());
4684 }
4685
4686 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4687 G1ParScanThreadState* par_scan_state) :
4688 _g1(g1), _par_scan_state(par_scan_state),
4689 _worker_id(par_scan_state->queue_num()) { }
4690
4691 void G1ParCopyHelper::mark_object(oop obj) {
4692 #ifdef ASSERT
4693 HeapRegion* hr = _g1->heap_region_containing(obj);
4694 assert(hr != NULL, "sanity");
4695 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4696 #endif // ASSERT
4697
4698 // We know that the object is not moving so it's safe to read its size.
4699 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4700 }
4701
4702 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4703 #ifdef ASSERT
4704 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4705 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4706 assert(from_obj != to_obj, "should not be self-forwarded");
4707
4708 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4709 assert(from_hr != NULL, "sanity");
4710 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4711
4712 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4713 assert(to_hr != NULL, "sanity");
4714 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4715 #endif // ASSERT
4716
4717 // The object might be in the process of being copied by another
4718 // worker so we cannot trust that its to-space image is
4719 // well-formed. So we have to read its size from its from-space
4720 // image which we know should not be changing.
4721 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4722 }
4723
4724 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4725 size_t word_sz = old->size();
4726 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4727 // +1 to make the -1 indexes valid...
4728 int young_index = from_region->young_index_in_cset()+1;
4729 assert( (from_region->is_young() && young_index > 0) ||
4730 (!from_region->is_young() && young_index == 0), "invariant" );
4731 G1CollectorPolicy* g1p = _g1h->g1_policy();
4732 markOop m = old->mark();
4733 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4734 : m->age();
4735 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4736 word_sz);
4737 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4738 #ifndef PRODUCT
4739 // Should this evacuation fail?
4740 if (_g1h->evacuation_should_fail()) {
4741 if (obj_ptr != NULL) {
4742 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4743 obj_ptr = NULL;
4744 }
4745 }
4746 #endif // !PRODUCT
4747
4748 if (obj_ptr == NULL) {
4749 // This will either forward-to-self, or detect that someone else has
4750 // installed a forwarding pointer.
4751 return _g1h->handle_evacuation_failure_par(this, old);
4752 }
4753
4754 oop obj = oop(obj_ptr);
4755
4756 // We're going to allocate linearly, so might as well prefetch ahead.
4757 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4758
4759 oop forward_ptr = old->forward_to_atomic(obj);
4760 if (forward_ptr == NULL) {
4761 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4762
4763 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4764 // we actually allocated from and update alloc_purpose accordingly
4765 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4766 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4767
4768 if (g1p->track_object_age(alloc_purpose)) {
4769 // We could simply do obj->incr_age(). However, this causes a
4770 // performance issue. obj->incr_age() will first check whether
4771 // the object has a displaced mark by checking its mark word;
4772 // getting the mark word from the new location of the object
4773 // stalls. So, given that we already have the mark word and we
4774 // are about to install it anyway, it's better to increase the
4775 // age on the mark word, when the object does not have a
4776 // displaced mark word. We're not expecting many objects to have
4777 // a displaced marked word, so that case is not optimized
4778 // further (it could be...) and we simply call obj->incr_age().
4779
4780 if (m->has_displaced_mark_helper()) {
4781 // in this case, we have to install the mark word first,
4782 // otherwise obj looks to be forwarded (the old mark word,
4783 // which contains the forward pointer, was copied)
4784 obj->set_mark(m);
4785 obj->incr_age();
4786 } else {
4787 m = m->incr_age();
4788 obj->set_mark(m);
4789 }
4790 age_table()->add(obj, word_sz);
4791 } else {
4792 obj->set_mark(m);
4793 }
4794
4795 if (G1StringDedup::is_enabled()) {
4796 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4797 to_region->is_young(),
4798 queue_num(),
4799 obj);
4800 }
4801
4802 size_t* surv_young_words = surviving_young_words();
4803 surv_young_words[young_index] += word_sz;
4804
4805 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4806 // We keep track of the next start index in the length field of
4807 // the to-space object. The actual length can be found in the
4808 // length field of the from-space object.
4809 arrayOop(obj)->set_length(0);
4810 oop* old_p = set_partial_array_mask(old);
4811 push_on_queue(old_p);
4812 } else {
4813 // No point in using the slower heap_region_containing() method,
4814 // given that we know obj is in the heap.
4815 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4816 obj->oop_iterate_backwards(&_scanner);
4817 }
4818 } else {
4819 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4820 obj = forward_ptr;
4821 }
4822 return obj;
4823 }
4824
4825 template <class T>
4826 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4827 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4828 _scanned_klass->record_modified_oops();
4829 }
4830 }
4831
4832 template <G1Barrier barrier, bool do_mark_object>
4833 template <class T>
4834 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4835 T heap_oop = oopDesc::load_heap_oop(p);
4836
4837 if (oopDesc::is_null(heap_oop)) {
4838 return;
4839 }
4840
4841 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4842
4843 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4844
4845 if (_g1->in_cset_fast_test(obj)) {
4846 oop forwardee;
4847 if (obj->is_forwarded()) {
4848 forwardee = obj->forwardee();
4849 } else {
4850 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4851 }
4852 assert(forwardee != NULL, "forwardee should not be NULL");
4853 oopDesc::encode_store_heap_oop(p, forwardee);
4854 if (do_mark_object && forwardee != obj) {
4855 // If the object is self-forwarded we don't need to explicitly
4856 // mark it, the evacuation failure protocol will do so.
4857 mark_forwarded_object(obj, forwardee);
4858 }
4859
4860 if (barrier == G1BarrierKlass) {
4861 do_klass_barrier(p, forwardee);
4862 }
4863 } else {
4864 // The object is not in collection set. If we're a root scanning
4865 // closure during an initial mark pause (i.e. do_mark_object will
4866 // be true) then attempt to mark the object.
4867 if (do_mark_object) {
4868 mark_object(obj);
4869 }
4870 }
4871
4872 if (barrier == G1BarrierEvac) {
4873 _par_scan_state->update_rs(_from, p, _worker_id);
4874 }
4875 }
4876
4877 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4878 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4879
4880 class G1ParEvacuateFollowersClosure : public VoidClosure {
4881 protected:
4882 G1CollectedHeap* _g1h;
4883 G1ParScanThreadState* _par_scan_state;
4884 RefToScanQueueSet* _queues;
4885 ParallelTaskTerminator* _terminator;
4886
4887 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4888 RefToScanQueueSet* queues() { return _queues; }
4889 ParallelTaskTerminator* terminator() { return _terminator; }
4890
4891 public:
4892 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4893 G1ParScanThreadState* par_scan_state,
4894 RefToScanQueueSet* queues,
4895 ParallelTaskTerminator* terminator)
4896 : _g1h(g1h), _par_scan_state(par_scan_state),
4897 _queues(queues), _terminator(terminator) {}
4898
4899 void do_void();
4900
4901 private:
4902 inline bool offer_termination();
4903 };
4904
4905 bool G1ParEvacuateFollowersClosure::offer_termination() {
4906 G1ParScanThreadState* const pss = par_scan_state();
4907 pss->start_term_time();
4908 const bool res = terminator()->offer_termination();
4909 pss->end_term_time();
4910 return res;
4911 }
4912
4913 void G1ParEvacuateFollowersClosure::do_void() {
4914 StarTask stolen_task;
4915 G1ParScanThreadState* const pss = par_scan_state();
4916 pss->trim_queue();
4917
4918 do {
4919 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4920 assert(pss->verify_task(stolen_task), "sanity");
4921 if (stolen_task.is_narrow()) {
4922 pss->deal_with_reference((narrowOop*) stolen_task);
4923 } else {
4924 pss->deal_with_reference((oop*) stolen_task);
4925 }
4926
4927 // We've just processed a reference and we might have made
4928 // available new entries on the queues. So we have to make sure
4929 // we drain the queues as necessary.
4930 pss->trim_queue();
4931 }
4932 } while (!offer_termination());
4933 }
4934
4935 class G1KlassScanClosure : public KlassClosure {
4936 G1ParCopyHelper* _closure;
4937 bool _process_only_dirty;
4938 int _count;
4939 public:
4940 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4941 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4942 void do_klass(Klass* klass) {
4943 // If the klass has not been dirtied we know that there's
4944 // no references into the young gen and we can skip it.
4945 if (!_process_only_dirty || klass->has_modified_oops()) {
4946 // Clean the klass since we're going to scavenge all the metadata.
4947 klass->clear_modified_oops();
4948
4949 // Tell the closure that this klass is the Klass to scavenge
4950 // and is the one to dirty if oops are left pointing into the young gen.
4951 _closure->set_scanned_klass(klass);
4952
4953 klass->oops_do(_closure);
4954
4955 _closure->set_scanned_klass(NULL);
4956 }
4957 _count++;
4958 }
4959 };
4960
4961 class G1ParTask : public AbstractGangTask {
4962 protected:
4963 G1CollectedHeap* _g1h;
4964 RefToScanQueueSet *_queues;
4965 ParallelTaskTerminator _terminator;
4966 uint _n_workers;
4967
4968 Mutex _stats_lock;
4969 Mutex* stats_lock() { return &_stats_lock; }
4970
4971 size_t getNCards() {
4972 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4973 / G1BlockOffsetSharedArray::N_bytes;
4974 }
4975
4976 public:
4977 G1ParTask(G1CollectedHeap* g1h,
4978 RefToScanQueueSet *task_queues)
4979 : AbstractGangTask("G1 collection"),
4980 _g1h(g1h),
4981 _queues(task_queues),
4982 _terminator(0, _queues),
4983 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4984 {}
4985
4986 RefToScanQueueSet* queues() { return _queues; }
4987
4988 RefToScanQueue *work_queue(int i) {
4989 return queues()->queue(i);
4990 }
4991
4992 ParallelTaskTerminator* terminator() { return &_terminator; }
4993
4994 virtual void set_for_termination(int active_workers) {
4995 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4996 // in the young space (_par_seq_tasks) in the G1 heap
4997 // for SequentialSubTasksDone.
4998 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4999 // both of which need setting by set_n_termination().
5000 _g1h->SharedHeap::set_n_termination(active_workers);
5001 _g1h->set_n_termination(active_workers);
5002 terminator()->reset_for_reuse(active_workers);
5003 _n_workers = active_workers;
5004 }
5005
5006 void work(uint worker_id) {
5007 if (worker_id >= _n_workers) return; // no work needed this round
5008
5009 double start_time_ms = os::elapsedTime() * 1000.0;
5010 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5011
5012 {
5013 ResourceMark rm;
5014 HandleMark hm;
5015
5016 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5017
5018 G1ParScanThreadState pss(_g1h, worker_id, rp);
5019 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5020
5021 pss.set_evac_failure_closure(&evac_failure_cl);
5022
5023 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5024 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5025
5026 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5027 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5028
5029 bool only_young = _g1h->g1_policy()->gcs_are_young();
5030 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5031 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5032
5033 OopClosure* scan_root_cl = &only_scan_root_cl;
5034 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5035
5036 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5037 // We also need to mark copied objects.
5038 scan_root_cl = &scan_mark_root_cl;
5039 scan_klasses_cl = &scan_mark_klasses_cl_s;
5040 }
5041
5042 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5043
5044 // Don't scan the scavengable methods in the code cache as part
5045 // of strong root scanning. The code roots that point into a
5046 // region in the collection set are scanned when we scan the
5047 // region's RSet.
5048 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5049
5050 pss.start_strong_roots();
5051 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5052 SharedHeap::ScanningOption(so),
5053 scan_root_cl,
5054 &push_heap_rs_cl,
5055 scan_klasses_cl,
5056 worker_id);
5057 pss.end_strong_roots();
5058
5059 {
5060 double start = os::elapsedTime();
5061 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5062 evac.do_void();
5063 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5064 double term_ms = pss.term_time()*1000.0;
5065 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5066 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5067 }
5068 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5069 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5070
5071 if (ParallelGCVerbose) {
5072 MutexLocker x(stats_lock());
5073 pss.print_termination_stats(worker_id);
5074 }
5075
5076 assert(pss.refs()->is_empty(), "should be empty");
5077
5078 // Close the inner scope so that the ResourceMark and HandleMark
5079 // destructors are executed here and are included as part of the
5080 // "GC Worker Time".
5081 }
5082
5083 double end_time_ms = os::elapsedTime() * 1000.0;
5084 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5085 }
5086 };
5087
5088 // *** Common G1 Evacuation Stuff
5089
5090 // This method is run in a GC worker.
5091
5092 void
5093 G1CollectedHeap::
5094 g1_process_strong_roots(bool is_scavenging,
5095 ScanningOption so,
5096 OopClosure* scan_non_heap_roots,
5097 OopsInHeapRegionClosure* scan_rs,
5098 G1KlassScanClosure* scan_klasses,
5099 uint worker_i) {
5100
5101 // First scan the strong roots
5102 double ext_roots_start = os::elapsedTime();
5103 double closure_app_time_sec = 0.0;
5104
5105 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5106
5107 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5108 // Walk the code cache/strong code roots w/o buffering, because StarTask
5109 // cannot handle unaligned oop locations.
5110 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5111
5112 process_strong_roots(false, // no scoping; this is parallel code
5113 is_scavenging, so,
5114 &buf_scan_non_heap_roots,
5115 &eager_scan_code_roots,
5116 scan_klasses
5117 );
5118
5119 // Now the CM ref_processor roots.
5120 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5121 // We need to treat the discovered reference lists of the
5122 // concurrent mark ref processor as roots and keep entries
5123 // (which are added by the marking threads) on them live
5124 // until they can be processed at the end of marking.
5125 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5126 }
5127
5128 // Finish up any enqueued closure apps (attributed as object copy time).
5129 buf_scan_non_heap_roots.done();
5130
5131 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5132
5133 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5134
5135 double ext_root_time_ms =
5136 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5137
5138 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5139
5140 // During conc marking we have to filter the per-thread SATB buffers
5141 // to make sure we remove any oops into the CSet (which will show up
5142 // as implicitly live).
5143 double satb_filtering_ms = 0.0;
5144 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5145 if (mark_in_progress()) {
5146 double satb_filter_start = os::elapsedTime();
5147
5148 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5149
5150 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5151 }
5152 }
5153 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5154
5155 // If this is an initial mark pause, and we're not scanning
5156 // the entire code cache, we need to mark the oops in the
5157 // strong code root lists for the regions that are not in
5158 // the collection set.
5159 // Note all threads participate in this set of root tasks.
5160 double mark_strong_code_roots_ms = 0.0;
5161 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5162 double mark_strong_roots_start = os::elapsedTime();
5163 mark_strong_code_roots(worker_i);
5164 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5165 }
5166 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5167
5168 // Now scan the complement of the collection set.
5169 if (scan_rs != NULL) {
5170 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5171 }
5172 _process_strong_tasks->all_tasks_completed();
5173 }
5174
5175 void
5176 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5177 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5178 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5179 }
5180
5181 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5182 private:
5183 BoolObjectClosure* _is_alive;
5184 int _initial_string_table_size;
5185 int _initial_symbol_table_size;
5186
5187 bool _process_strings;
5188 int _strings_processed;
5189 int _strings_removed;
5190
5191 bool _process_symbols;
5192 int _symbols_processed;
5193 int _symbols_removed;
5194
5195 bool _do_in_parallel;
5196 public:
5197 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5198 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5199 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5200 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5201 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5202
5203 _initial_string_table_size = StringTable::the_table()->table_size();
5204 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5205 if (process_strings) {
5206 StringTable::clear_parallel_claimed_index();
5207 }
5208 if (process_symbols) {
5209 SymbolTable::clear_parallel_claimed_index();
5210 }
5211 }
5212
5213 ~G1StringSymbolTableUnlinkTask() {
5214 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5215 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5216 StringTable::parallel_claimed_index(), _initial_string_table_size));
5217 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5218 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5219 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5220 }
5221
5222 void work(uint worker_id) {
5223 if (_do_in_parallel) {
5224 int strings_processed = 0;
5225 int strings_removed = 0;
5226 int symbols_processed = 0;
5227 int symbols_removed = 0;
5228 if (_process_strings) {
5229 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5230 Atomic::add(strings_processed, &_strings_processed);
5231 Atomic::add(strings_removed, &_strings_removed);
5232 }
5233 if (_process_symbols) {
5234 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5235 Atomic::add(symbols_processed, &_symbols_processed);
5236 Atomic::add(symbols_removed, &_symbols_removed);
5237 }
5238 } else {
5239 if (_process_strings) {
5240 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5241 }
5242 if (_process_symbols) {
5243 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5244 }
5245 }
5246 }
5247
5248 size_t strings_processed() const { return (size_t)_strings_processed; }
5249 size_t strings_removed() const { return (size_t)_strings_removed; }
5250
5251 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5252 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5253 };
5254
5255 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5256 bool process_strings, bool process_symbols) {
5257 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5258 _g1h->workers()->active_workers() : 1);
5259
5260 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5261 if (G1CollectedHeap::use_parallel_gc_threads()) {
5262 set_par_threads(n_workers);
5263 workers()->run_task(&g1_unlink_task);
5264 set_par_threads(0);
5265 } else {
5266 g1_unlink_task.work(0);
5267 }
5268 if (G1TraceStringSymbolTableScrubbing) {
5269 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5270 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5271 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5272 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5273 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5274 }
5275
5276 if (G1StringDedup::is_enabled()) {
5277 G1StringDedup::unlink(is_alive);
5278 }
5279 }
5280
5281 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5282 private:
5283 DirtyCardQueueSet* _queue;
5284 public:
5285 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5286
5287 virtual void work(uint worker_id) {
5288 double start_time = os::elapsedTime();
5289
5290 RedirtyLoggedCardTableEntryClosure cl;
5291 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5292 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5293 } else {
5294 _queue->apply_closure_to_all_completed_buffers(&cl);
5295 }
5296
5297 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5298 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5299 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5300 }
5301 };
5302
5303 void G1CollectedHeap::redirty_logged_cards() {
5304 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5305 double redirty_logged_cards_start = os::elapsedTime();
5306
5307 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5308 _g1h->workers()->active_workers() : 1);
5309
5310 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5311 dirty_card_queue_set().reset_for_par_iteration();
5312 if (use_parallel_gc_threads()) {
5313 set_par_threads(n_workers);
5314 workers()->run_task(&redirty_task);
5315 set_par_threads(0);
5316 } else {
5317 redirty_task.work(0);
5318 }
5319
5320 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5321 dcq.merge_bufferlists(&dirty_card_queue_set());
5322 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5323
5324 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5325 }
5326
5327 // Weak Reference Processing support
5328
5329 // An always "is_alive" closure that is used to preserve referents.
5330 // If the object is non-null then it's alive. Used in the preservation
5331 // of referent objects that are pointed to by reference objects
5332 // discovered by the CM ref processor.
5333 class G1AlwaysAliveClosure: public BoolObjectClosure {
5334 G1CollectedHeap* _g1;
5335 public:
5336 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5337 bool do_object_b(oop p) {
5338 if (p != NULL) {
5339 return true;
5340 }
5341 return false;
5342 }
5343 };
5344
5345 bool G1STWIsAliveClosure::do_object_b(oop p) {
5346 // An object is reachable if it is outside the collection set,
5347 // or is inside and copied.
5348 return !_g1->obj_in_cs(p) || p->is_forwarded();
5349 }
5350
5351 // Non Copying Keep Alive closure
5352 class G1KeepAliveClosure: public OopClosure {
5353 G1CollectedHeap* _g1;
5354 public:
5355 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5356 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5357 void do_oop( oop* p) {
5358 oop obj = *p;
5359
5360 if (_g1->obj_in_cs(obj)) {
5361 assert( obj->is_forwarded(), "invariant" );
5362 *p = obj->forwardee();
5363 }
5364 }
5365 };
5366
5367 // Copying Keep Alive closure - can be called from both
5368 // serial and parallel code as long as different worker
5369 // threads utilize different G1ParScanThreadState instances
5370 // and different queues.
5371
5372 class G1CopyingKeepAliveClosure: public OopClosure {
5373 G1CollectedHeap* _g1h;
5374 OopClosure* _copy_non_heap_obj_cl;
5375 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5376 G1ParScanThreadState* _par_scan_state;
5377
5378 public:
5379 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5380 OopClosure* non_heap_obj_cl,
5381 OopsInHeapRegionClosure* metadata_obj_cl,
5382 G1ParScanThreadState* pss):
5383 _g1h(g1h),
5384 _copy_non_heap_obj_cl(non_heap_obj_cl),
5385 _copy_metadata_obj_cl(metadata_obj_cl),
5386 _par_scan_state(pss)
5387 {}
5388
5389 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5390 virtual void do_oop( oop* p) { do_oop_work(p); }
5391
5392 template <class T> void do_oop_work(T* p) {
5393 oop obj = oopDesc::load_decode_heap_oop(p);
5394
5395 if (_g1h->obj_in_cs(obj)) {
5396 // If the referent object has been forwarded (either copied
5397 // to a new location or to itself in the event of an
5398 // evacuation failure) then we need to update the reference
5399 // field and, if both reference and referent are in the G1
5400 // heap, update the RSet for the referent.
5401 //
5402 // If the referent has not been forwarded then we have to keep
5403 // it alive by policy. Therefore we have copy the referent.
5404 //
5405 // If the reference field is in the G1 heap then we can push
5406 // on the PSS queue. When the queue is drained (after each
5407 // phase of reference processing) the object and it's followers
5408 // will be copied, the reference field set to point to the
5409 // new location, and the RSet updated. Otherwise we need to
5410 // use the the non-heap or metadata closures directly to copy
5411 // the referent object and update the pointer, while avoiding
5412 // updating the RSet.
5413
5414 if (_g1h->is_in_g1_reserved(p)) {
5415 _par_scan_state->push_on_queue(p);
5416 } else {
5417 assert(!Metaspace::contains((const void*)p),
5418 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5419 PTR_FORMAT, p));
5420 _copy_non_heap_obj_cl->do_oop(p);
5421 }
5422 }
5423 }
5424 };
5425
5426 // Serial drain queue closure. Called as the 'complete_gc'
5427 // closure for each discovered list in some of the
5428 // reference processing phases.
5429
5430 class G1STWDrainQueueClosure: public VoidClosure {
5431 protected:
5432 G1CollectedHeap* _g1h;
5433 G1ParScanThreadState* _par_scan_state;
5434
5435 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5436
5437 public:
5438 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5439 _g1h(g1h),
5440 _par_scan_state(pss)
5441 { }
5442
5443 void do_void() {
5444 G1ParScanThreadState* const pss = par_scan_state();
5445 pss->trim_queue();
5446 }
5447 };
5448
5449 // Parallel Reference Processing closures
5450
5451 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5452 // processing during G1 evacuation pauses.
5453
5454 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5455 private:
5456 G1CollectedHeap* _g1h;
5457 RefToScanQueueSet* _queues;
5458 FlexibleWorkGang* _workers;
5459 int _active_workers;
5460
5461 public:
5462 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5463 FlexibleWorkGang* workers,
5464 RefToScanQueueSet *task_queues,
5465 int n_workers) :
5466 _g1h(g1h),
5467 _queues(task_queues),
5468 _workers(workers),
5469 _active_workers(n_workers)
5470 {
5471 assert(n_workers > 0, "shouldn't call this otherwise");
5472 }
5473
5474 // Executes the given task using concurrent marking worker threads.
5475 virtual void execute(ProcessTask& task);
5476 virtual void execute(EnqueueTask& task);
5477 };
5478
5479 // Gang task for possibly parallel reference processing
5480
5481 class G1STWRefProcTaskProxy: public AbstractGangTask {
5482 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5483 ProcessTask& _proc_task;
5484 G1CollectedHeap* _g1h;
5485 RefToScanQueueSet *_task_queues;
5486 ParallelTaskTerminator* _terminator;
5487
5488 public:
5489 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5490 G1CollectedHeap* g1h,
5491 RefToScanQueueSet *task_queues,
5492 ParallelTaskTerminator* terminator) :
5493 AbstractGangTask("Process reference objects in parallel"),
5494 _proc_task(proc_task),
5495 _g1h(g1h),
5496 _task_queues(task_queues),
5497 _terminator(terminator)
5498 {}
5499
5500 virtual void work(uint worker_id) {
5501 // The reference processing task executed by a single worker.
5502 ResourceMark rm;
5503 HandleMark hm;
5504
5505 G1STWIsAliveClosure is_alive(_g1h);
5506
5507 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5508 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5509
5510 pss.set_evac_failure_closure(&evac_failure_cl);
5511
5512 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5513 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5514
5515 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5516 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5517
5518 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5519 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5520
5521 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5522 // We also need to mark copied objects.
5523 copy_non_heap_cl = ©_mark_non_heap_cl;
5524 copy_metadata_cl = ©_mark_metadata_cl;
5525 }
5526
5527 // Keep alive closure.
5528 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5529
5530 // Complete GC closure
5531 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5532
5533 // Call the reference processing task's work routine.
5534 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5535
5536 // Note we cannot assert that the refs array is empty here as not all
5537 // of the processing tasks (specifically phase2 - pp2_work) execute
5538 // the complete_gc closure (which ordinarily would drain the queue) so
5539 // the queue may not be empty.
5540 }
5541 };
5542
5543 // Driver routine for parallel reference processing.
5544 // Creates an instance of the ref processing gang
5545 // task and has the worker threads execute it.
5546 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5547 assert(_workers != NULL, "Need parallel worker threads.");
5548
5549 ParallelTaskTerminator terminator(_active_workers, _queues);
5550 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5551
5552 _g1h->set_par_threads(_active_workers);
5553 _workers->run_task(&proc_task_proxy);
5554 _g1h->set_par_threads(0);
5555 }
5556
5557 // Gang task for parallel reference enqueueing.
5558
5559 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5560 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5561 EnqueueTask& _enq_task;
5562
5563 public:
5564 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5565 AbstractGangTask("Enqueue reference objects in parallel"),
5566 _enq_task(enq_task)
5567 { }
5568
5569 virtual void work(uint worker_id) {
5570 _enq_task.work(worker_id);
5571 }
5572 };
5573
5574 // Driver routine for parallel reference enqueueing.
5575 // Creates an instance of the ref enqueueing gang
5576 // task and has the worker threads execute it.
5577
5578 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5579 assert(_workers != NULL, "Need parallel worker threads.");
5580
5581 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5582
5583 _g1h->set_par_threads(_active_workers);
5584 _workers->run_task(&enq_task_proxy);
5585 _g1h->set_par_threads(0);
5586 }
5587
5588 // End of weak reference support closures
5589
5590 // Abstract task used to preserve (i.e. copy) any referent objects
5591 // that are in the collection set and are pointed to by reference
5592 // objects discovered by the CM ref processor.
5593
5594 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5595 protected:
5596 G1CollectedHeap* _g1h;
5597 RefToScanQueueSet *_queues;
5598 ParallelTaskTerminator _terminator;
5599 uint _n_workers;
5600
5601 public:
5602 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5603 AbstractGangTask("ParPreserveCMReferents"),
5604 _g1h(g1h),
5605 _queues(task_queues),
5606 _terminator(workers, _queues),
5607 _n_workers(workers)
5608 { }
5609
5610 void work(uint worker_id) {
5611 ResourceMark rm;
5612 HandleMark hm;
5613
5614 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5615 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5616
5617 pss.set_evac_failure_closure(&evac_failure_cl);
5618
5619 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5620
5621
5622 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5623 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5624
5625 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5626 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5627
5628 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5629 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5630
5631 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5632 // We also need to mark copied objects.
5633 copy_non_heap_cl = ©_mark_non_heap_cl;
5634 copy_metadata_cl = ©_mark_metadata_cl;
5635 }
5636
5637 // Is alive closure
5638 G1AlwaysAliveClosure always_alive(_g1h);
5639
5640 // Copying keep alive closure. Applied to referent objects that need
5641 // to be copied.
5642 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5643
5644 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5645
5646 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5647 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5648
5649 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5650 // So this must be true - but assert just in case someone decides to
5651 // change the worker ids.
5652 assert(0 <= worker_id && worker_id < limit, "sanity");
5653 assert(!rp->discovery_is_atomic(), "check this code");
5654
5655 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5656 for (uint idx = worker_id; idx < limit; idx += stride) {
5657 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5658
5659 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5660 while (iter.has_next()) {
5661 // Since discovery is not atomic for the CM ref processor, we
5662 // can see some null referent objects.
5663 iter.load_ptrs(DEBUG_ONLY(true));
5664 oop ref = iter.obj();
5665
5666 // This will filter nulls.
5667 if (iter.is_referent_alive()) {
5668 iter.make_referent_alive();
5669 }
5670 iter.move_to_next();
5671 }
5672 }
5673
5674 // Drain the queue - which may cause stealing
5675 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5676 drain_queue.do_void();
5677 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5678 assert(pss.refs()->is_empty(), "should be");
5679 }
5680 };
5681
5682 // Weak Reference processing during an evacuation pause (part 1).
5683 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5684 double ref_proc_start = os::elapsedTime();
5685
5686 ReferenceProcessor* rp = _ref_processor_stw;
5687 assert(rp->discovery_enabled(), "should have been enabled");
5688
5689 // Any reference objects, in the collection set, that were 'discovered'
5690 // by the CM ref processor should have already been copied (either by
5691 // applying the external root copy closure to the discovered lists, or
5692 // by following an RSet entry).
5693 //
5694 // But some of the referents, that are in the collection set, that these
5695 // reference objects point to may not have been copied: the STW ref
5696 // processor would have seen that the reference object had already
5697 // been 'discovered' and would have skipped discovering the reference,
5698 // but would not have treated the reference object as a regular oop.
5699 // As a result the copy closure would not have been applied to the
5700 // referent object.
5701 //
5702 // We need to explicitly copy these referent objects - the references
5703 // will be processed at the end of remarking.
5704 //
5705 // We also need to do this copying before we process the reference
5706 // objects discovered by the STW ref processor in case one of these
5707 // referents points to another object which is also referenced by an
5708 // object discovered by the STW ref processor.
5709
5710 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5711 no_of_gc_workers == workers()->active_workers(),
5712 "Need to reset active GC workers");
5713
5714 set_par_threads(no_of_gc_workers);
5715 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5716 no_of_gc_workers,
5717 _task_queues);
5718
5719 if (G1CollectedHeap::use_parallel_gc_threads()) {
5720 workers()->run_task(&keep_cm_referents);
5721 } else {
5722 keep_cm_referents.work(0);
5723 }
5724
5725 set_par_threads(0);
5726
5727 // Closure to test whether a referent is alive.
5728 G1STWIsAliveClosure is_alive(this);
5729
5730 // Even when parallel reference processing is enabled, the processing
5731 // of JNI refs is serial and performed serially by the current thread
5732 // rather than by a worker. The following PSS will be used for processing
5733 // JNI refs.
5734
5735 // Use only a single queue for this PSS.
5736 G1ParScanThreadState pss(this, 0, NULL);
5737
5738 // We do not embed a reference processor in the copying/scanning
5739 // closures while we're actually processing the discovered
5740 // reference objects.
5741 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5742
5743 pss.set_evac_failure_closure(&evac_failure_cl);
5744
5745 assert(pss.refs()->is_empty(), "pre-condition");
5746
5747 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5748 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5749
5750 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5751 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5752
5753 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5754 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5755
5756 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5757 // We also need to mark copied objects.
5758 copy_non_heap_cl = ©_mark_non_heap_cl;
5759 copy_metadata_cl = ©_mark_metadata_cl;
5760 }
5761
5762 // Keep alive closure.
5763 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5764
5765 // Serial Complete GC closure
5766 G1STWDrainQueueClosure drain_queue(this, &pss);
5767
5768 // Setup the soft refs policy...
5769 rp->setup_policy(false);
5770
5771 ReferenceProcessorStats stats;
5772 if (!rp->processing_is_mt()) {
5773 // Serial reference processing...
5774 stats = rp->process_discovered_references(&is_alive,
5775 &keep_alive,
5776 &drain_queue,
5777 NULL,
5778 _gc_timer_stw,
5779 _gc_tracer_stw->gc_id());
5780 } else {
5781 // Parallel reference processing
5782 assert(rp->num_q() == no_of_gc_workers, "sanity");
5783 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5784
5785 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5786 stats = rp->process_discovered_references(&is_alive,
5787 &keep_alive,
5788 &drain_queue,
5789 &par_task_executor,
5790 _gc_timer_stw,
5791 _gc_tracer_stw->gc_id());
5792 }
5793
5794 _gc_tracer_stw->report_gc_reference_stats(stats);
5795
5796 // We have completed copying any necessary live referent objects.
5797 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5798
5799 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5800 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5801 }
5802
5803 // Weak Reference processing during an evacuation pause (part 2).
5804 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5805 double ref_enq_start = os::elapsedTime();
5806
5807 ReferenceProcessor* rp = _ref_processor_stw;
5808 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5809
5810 // Now enqueue any remaining on the discovered lists on to
5811 // the pending list.
5812 if (!rp->processing_is_mt()) {
5813 // Serial reference processing...
5814 rp->enqueue_discovered_references();
5815 } else {
5816 // Parallel reference enqueueing
5817
5818 assert(no_of_gc_workers == workers()->active_workers(),
5819 "Need to reset active workers");
5820 assert(rp->num_q() == no_of_gc_workers, "sanity");
5821 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5822
5823 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5824 rp->enqueue_discovered_references(&par_task_executor);
5825 }
5826
5827 rp->verify_no_references_recorded();
5828 assert(!rp->discovery_enabled(), "should have been disabled");
5829
5830 // FIXME
5831 // CM's reference processing also cleans up the string and symbol tables.
5832 // Should we do that here also? We could, but it is a serial operation
5833 // and could significantly increase the pause time.
5834
5835 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5836 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5837 }
5838
5839 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5840 _expand_heap_after_alloc_failure = true;
5841 _evacuation_failed = false;
5842
5843 // Should G1EvacuationFailureALot be in effect for this GC?
5844 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5845
5846 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5847
5848 // Disable the hot card cache.
5849 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5850 hot_card_cache->reset_hot_cache_claimed_index();
5851 hot_card_cache->set_use_cache(false);
5852
5853 uint n_workers;
5854 if (G1CollectedHeap::use_parallel_gc_threads()) {
5855 n_workers =
5856 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5857 workers()->active_workers(),
5858 Threads::number_of_non_daemon_threads());
5859 assert(UseDynamicNumberOfGCThreads ||
5860 n_workers == workers()->total_workers(),
5861 "If not dynamic should be using all the workers");
5862 workers()->set_active_workers(n_workers);
5863 set_par_threads(n_workers);
5864 } else {
5865 assert(n_par_threads() == 0,
5866 "Should be the original non-parallel value");
5867 n_workers = 1;
5868 }
5869
5870 G1ParTask g1_par_task(this, _task_queues);
5871
5872 init_for_evac_failure(NULL);
5873
5874 rem_set()->prepare_for_younger_refs_iterate(true);
5875
5876 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5877 double start_par_time_sec = os::elapsedTime();
5878 double end_par_time_sec;
5879
5880 {
5881 StrongRootsScope srs(this);
5882
5883 if (G1CollectedHeap::use_parallel_gc_threads()) {
5884 // The individual threads will set their evac-failure closures.
5885 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5886 // These tasks use ShareHeap::_process_strong_tasks
5887 assert(UseDynamicNumberOfGCThreads ||
5888 workers()->active_workers() == workers()->total_workers(),
5889 "If not dynamic should be using all the workers");
5890 workers()->run_task(&g1_par_task);
5891 } else {
5892 g1_par_task.set_for_termination(n_workers);
5893 g1_par_task.work(0);
5894 }
5895 end_par_time_sec = os::elapsedTime();
5896
5897 // Closing the inner scope will execute the destructor
5898 // for the StrongRootsScope object. We record the current
5899 // elapsed time before closing the scope so that time
5900 // taken for the SRS destructor is NOT included in the
5901 // reported parallel time.
5902 }
5903
5904 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5905 g1_policy()->phase_times()->record_par_time(par_time_ms);
5906
5907 double code_root_fixup_time_ms =
5908 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5909 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5910
5911 set_par_threads(0);
5912
5913 // Process any discovered reference objects - we have
5914 // to do this _before_ we retire the GC alloc regions
5915 // as we may have to copy some 'reachable' referent
5916 // objects (and their reachable sub-graphs) that were
5917 // not copied during the pause.
5918 process_discovered_references(n_workers);
5919
5920 // Weak root processing.
5921 {
5922 G1STWIsAliveClosure is_alive(this);
5923 G1KeepAliveClosure keep_alive(this);
5924 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5925 if (G1StringDedup::is_enabled()) {
5926 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5927 }
5928 }
5929
5930 release_gc_alloc_regions(n_workers, evacuation_info);
5931 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5932
5933 // Reset and re-enable the hot card cache.
5934 // Note the counts for the cards in the regions in the
5935 // collection set are reset when the collection set is freed.
5936 hot_card_cache->reset_hot_cache();
5937 hot_card_cache->set_use_cache(true);
5938
5939 // Migrate the strong code roots attached to each region in
5940 // the collection set. Ideally we would like to do this
5941 // after we have finished the scanning/evacuation of the
5942 // strong code roots for a particular heap region.
5943 migrate_strong_code_roots();
5944
5945 purge_code_root_memory();
5946
5947 if (g1_policy()->during_initial_mark_pause()) {
5948 // Reset the claim values set during marking the strong code roots
5949 reset_heap_region_claim_values();
5950 }
5951
5952 finalize_for_evac_failure();
5953
5954 if (evacuation_failed()) {
5955 remove_self_forwarding_pointers();
5956
5957 // Reset the G1EvacuationFailureALot counters and flags
5958 // Note: the values are reset only when an actual
5959 // evacuation failure occurs.
5960 NOT_PRODUCT(reset_evacuation_should_fail();)
5961 }
5962
5963 // Enqueue any remaining references remaining on the STW
5964 // reference processor's discovered lists. We need to do
5965 // this after the card table is cleaned (and verified) as
5966 // the act of enqueueing entries on to the pending list
5967 // will log these updates (and dirty their associated
5968 // cards). We need these updates logged to update any
5969 // RSets.
5970 enqueue_discovered_references(n_workers);
5971
5972 if (G1DeferredRSUpdate) {
5973 redirty_logged_cards();
5974 }
5975 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5976 }
5977
5978 void G1CollectedHeap::free_region(HeapRegion* hr,
5979 FreeRegionList* free_list,
5980 bool par,
5981 bool locked) {
5982 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5983 assert(!hr->is_empty(), "the region should not be empty");
5984 assert(free_list != NULL, "pre-condition");
5985
5986 // Clear the card counts for this region.
5987 // Note: we only need to do this if the region is not young
5988 // (since we don't refine cards in young regions).
5989 if (!hr->is_young()) {
5990 _cg1r->hot_card_cache()->reset_card_counts(hr);
5991 }
5992 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5993 free_list->add_ordered(hr);
5994 }
5995
5996 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5997 FreeRegionList* free_list,
5998 bool par) {
5999 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6000 assert(free_list != NULL, "pre-condition");
6001
6002 size_t hr_capacity = hr->capacity();
6003 // We need to read this before we make the region non-humongous,
6004 // otherwise the information will be gone.
6005 uint last_index = hr->last_hc_index();
6006 hr->set_notHumongous();
6007 free_region(hr, free_list, par);
6008
6009 uint i = hr->hrs_index() + 1;
6010 while (i < last_index) {
6011 HeapRegion* curr_hr = region_at(i);
6012 assert(curr_hr->continuesHumongous(), "invariant");
6013 curr_hr->set_notHumongous();
6014 free_region(curr_hr, free_list, par);
6015 i += 1;
6016 }
6017 }
6018
6019 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6020 const HeapRegionSetCount& humongous_regions_removed) {
6021 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6022 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6023 _old_set.bulk_remove(old_regions_removed);
6024 _humongous_set.bulk_remove(humongous_regions_removed);
6025 }
6026
6027 }
6028
6029 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6030 assert(list != NULL, "list can't be null");
6031 if (!list->is_empty()) {
6032 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6033 _free_list.add_ordered(list);
6034 }
6035 }
6036
6037 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6038 assert(_summary_bytes_used >= bytes,
6039 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6040 _summary_bytes_used, bytes));
6041 _summary_bytes_used -= bytes;
6042 }
6043
6044 class G1ParCleanupCTTask : public AbstractGangTask {
6045 G1SATBCardTableModRefBS* _ct_bs;
6046 G1CollectedHeap* _g1h;
6047 HeapRegion* volatile _su_head;
6048 public:
6049 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6050 G1CollectedHeap* g1h) :
6051 AbstractGangTask("G1 Par Cleanup CT Task"),
6052 _ct_bs(ct_bs), _g1h(g1h) { }
6053
6054 void work(uint worker_id) {
6055 HeapRegion* r;
6056 while (r = _g1h->pop_dirty_cards_region()) {
6057 clear_cards(r);
6058 }
6059 }
6060
6061 void clear_cards(HeapRegion* r) {
6062 // Cards of the survivors should have already been dirtied.
6063 if (!r->is_survivor()) {
6064 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6065 }
6066 }
6067 };
6068
6069 #ifndef PRODUCT
6070 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6071 G1CollectedHeap* _g1h;
6072 G1SATBCardTableModRefBS* _ct_bs;
6073 public:
6074 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6075 : _g1h(g1h), _ct_bs(ct_bs) { }
6076 virtual bool doHeapRegion(HeapRegion* r) {
6077 if (r->is_survivor()) {
6078 _g1h->verify_dirty_region(r);
6079 } else {
6080 _g1h->verify_not_dirty_region(r);
6081 }
6082 return false;
6083 }
6084 };
6085
6086 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6087 // All of the region should be clean.
6088 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6089 MemRegion mr(hr->bottom(), hr->end());
6090 ct_bs->verify_not_dirty_region(mr);
6091 }
6092
6093 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6094 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6095 // dirty allocated blocks as they allocate them. The thread that
6096 // retires each region and replaces it with a new one will do a
6097 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6098 // not dirty that area (one less thing to have to do while holding
6099 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6100 // is dirty.
6101 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6102 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6103 if (hr->is_young()) {
6104 ct_bs->verify_g1_young_region(mr);
6105 } else {
6106 ct_bs->verify_dirty_region(mr);
6107 }
6108 }
6109
6110 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6111 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6112 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6113 verify_dirty_region(hr);
6114 }
6115 }
6116
6117 void G1CollectedHeap::verify_dirty_young_regions() {
6118 verify_dirty_young_list(_young_list->first_region());
6119 }
6120 #endif
6121
6122 void G1CollectedHeap::cleanUpCardTable() {
6123 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6124 double start = os::elapsedTime();
6125
6126 {
6127 // Iterate over the dirty cards region list.
6128 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6129
6130 if (G1CollectedHeap::use_parallel_gc_threads()) {
6131 set_par_threads();
6132 workers()->run_task(&cleanup_task);
6133 set_par_threads(0);
6134 } else {
6135 while (_dirty_cards_region_list) {
6136 HeapRegion* r = _dirty_cards_region_list;
6137 cleanup_task.clear_cards(r);
6138 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6139 if (_dirty_cards_region_list == r) {
6140 // The last region.
6141 _dirty_cards_region_list = NULL;
6142 }
6143 r->set_next_dirty_cards_region(NULL);
6144 }
6145 }
6146 #ifndef PRODUCT
6147 if (G1VerifyCTCleanup || VerifyAfterGC) {
6148 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6149 heap_region_iterate(&cleanup_verifier);
6150 }
6151 #endif
6152 }
6153
6154 double elapsed = os::elapsedTime() - start;
6155 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6156 }
6157
6158 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6159 size_t pre_used = 0;
6160 FreeRegionList local_free_list("Local List for CSet Freeing");
6161
6162 double young_time_ms = 0.0;
6163 double non_young_time_ms = 0.0;
6164
6165 // Since the collection set is a superset of the the young list,
6166 // all we need to do to clear the young list is clear its
6167 // head and length, and unlink any young regions in the code below
6168 _young_list->clear();
6169
6170 G1CollectorPolicy* policy = g1_policy();
6171
6172 double start_sec = os::elapsedTime();
6173 bool non_young = true;
6174
6175 HeapRegion* cur = cs_head;
6176 int age_bound = -1;
6177 size_t rs_lengths = 0;
6178
6179 while (cur != NULL) {
6180 assert(!is_on_master_free_list(cur), "sanity");
6181 if (non_young) {
6182 if (cur->is_young()) {
6183 double end_sec = os::elapsedTime();
6184 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6185 non_young_time_ms += elapsed_ms;
6186
6187 start_sec = os::elapsedTime();
6188 non_young = false;
6189 }
6190 } else {
6191 if (!cur->is_young()) {
6192 double end_sec = os::elapsedTime();
6193 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6194 young_time_ms += elapsed_ms;
6195
6196 start_sec = os::elapsedTime();
6197 non_young = true;
6198 }
6199 }
6200
6201 rs_lengths += cur->rem_set()->occupied_locked();
6202
6203 HeapRegion* next = cur->next_in_collection_set();
6204 assert(cur->in_collection_set(), "bad CS");
6205 cur->set_next_in_collection_set(NULL);
6206 cur->set_in_collection_set(false);
6207
6208 if (cur->is_young()) {
6209 int index = cur->young_index_in_cset();
6210 assert(index != -1, "invariant");
6211 assert((uint) index < policy->young_cset_region_length(), "invariant");
6212 size_t words_survived = _surviving_young_words[index];
6213 cur->record_surv_words_in_group(words_survived);
6214
6215 // At this point the we have 'popped' cur from the collection set
6216 // (linked via next_in_collection_set()) but it is still in the
6217 // young list (linked via next_young_region()). Clear the
6218 // _next_young_region field.
6219 cur->set_next_young_region(NULL);
6220 } else {
6221 int index = cur->young_index_in_cset();
6222 assert(index == -1, "invariant");
6223 }
6224
6225 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6226 (!cur->is_young() && cur->young_index_in_cset() == -1),
6227 "invariant" );
6228
6229 if (!cur->evacuation_failed()) {
6230 MemRegion used_mr = cur->used_region();
6231
6232 // And the region is empty.
6233 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6234 pre_used += cur->used();
6235 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6236 } else {
6237 cur->uninstall_surv_rate_group();
6238 if (cur->is_young()) {
6239 cur->set_young_index_in_cset(-1);
6240 }
6241 cur->set_not_young();
6242 cur->set_evacuation_failed(false);
6243 // The region is now considered to be old.
6244 _old_set.add(cur);
6245 evacuation_info.increment_collectionset_used_after(cur->used());
6246 }
6247 cur = next;
6248 }
6249
6250 evacuation_info.set_regions_freed(local_free_list.length());
6251 policy->record_max_rs_lengths(rs_lengths);
6252 policy->cset_regions_freed();
6253
6254 double end_sec = os::elapsedTime();
6255 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6256
6257 if (non_young) {
6258 non_young_time_ms += elapsed_ms;
6259 } else {
6260 young_time_ms += elapsed_ms;
6261 }
6262
6263 prepend_to_freelist(&local_free_list);
6264 decrement_summary_bytes(pre_used);
6265 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6266 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6267 }
6268
6269 // This routine is similar to the above but does not record
6270 // any policy statistics or update free lists; we are abandoning
6271 // the current incremental collection set in preparation of a
6272 // full collection. After the full GC we will start to build up
6273 // the incremental collection set again.
6274 // This is only called when we're doing a full collection
6275 // and is immediately followed by the tearing down of the young list.
6276
6277 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6278 HeapRegion* cur = cs_head;
6279
6280 while (cur != NULL) {
6281 HeapRegion* next = cur->next_in_collection_set();
6282 assert(cur->in_collection_set(), "bad CS");
6283 cur->set_next_in_collection_set(NULL);
6284 cur->set_in_collection_set(false);
6285 cur->set_young_index_in_cset(-1);
6286 cur = next;
6287 }
6288 }
6289
6290 void G1CollectedHeap::set_free_regions_coming() {
6291 if (G1ConcRegionFreeingVerbose) {
6292 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6293 "setting free regions coming");
6294 }
6295
6296 assert(!free_regions_coming(), "pre-condition");
6297 _free_regions_coming = true;
6298 }
6299
6300 void G1CollectedHeap::reset_free_regions_coming() {
6301 assert(free_regions_coming(), "pre-condition");
6302
6303 {
6304 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6305 _free_regions_coming = false;
6306 SecondaryFreeList_lock->notify_all();
6307 }
6308
6309 if (G1ConcRegionFreeingVerbose) {
6310 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6311 "reset free regions coming");
6312 }
6313 }
6314
6315 void G1CollectedHeap::wait_while_free_regions_coming() {
6316 // Most of the time we won't have to wait, so let's do a quick test
6317 // first before we take the lock.
6318 if (!free_regions_coming()) {
6319 return;
6320 }
6321
6322 if (G1ConcRegionFreeingVerbose) {
6323 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6324 "waiting for free regions");
6325 }
6326
6327 {
6328 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6329 while (free_regions_coming()) {
6330 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6331 }
6332 }
6333
6334 if (G1ConcRegionFreeingVerbose) {
6335 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6336 "done waiting for free regions");
6337 }
6338 }
6339
6340 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6341 assert(heap_lock_held_for_gc(),
6342 "the heap lock should already be held by or for this thread");
6343 _young_list->push_region(hr);
6344 }
6345
6346 class NoYoungRegionsClosure: public HeapRegionClosure {
6347 private:
6348 bool _success;
6349 public:
6350 NoYoungRegionsClosure() : _success(true) { }
6351 bool doHeapRegion(HeapRegion* r) {
6352 if (r->is_young()) {
6353 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6354 r->bottom(), r->end());
6355 _success = false;
6356 }
6357 return false;
6358 }
6359 bool success() { return _success; }
6360 };
6361
6362 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6363 bool ret = _young_list->check_list_empty(check_sample);
6364
6365 if (check_heap) {
6366 NoYoungRegionsClosure closure;
6367 heap_region_iterate(&closure);
6368 ret = ret && closure.success();
6369 }
6370
6371 return ret;
6372 }
6373
6374 class TearDownRegionSetsClosure : public HeapRegionClosure {
6375 private:
6376 HeapRegionSet *_old_set;
6377
6378 public:
6379 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6380
6381 bool doHeapRegion(HeapRegion* r) {
6382 if (r->is_empty()) {
6383 // We ignore empty regions, we'll empty the free list afterwards
6384 } else if (r->is_young()) {
6385 // We ignore young regions, we'll empty the young list afterwards
6386 } else if (r->isHumongous()) {
6387 // We ignore humongous regions, we're not tearing down the
6388 // humongous region set
6389 } else {
6390 // The rest should be old
6391 _old_set->remove(r);
6392 }
6393 return false;
6394 }
6395
6396 ~TearDownRegionSetsClosure() {
6397 assert(_old_set->is_empty(), "post-condition");
6398 }
6399 };
6400
6401 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6402 assert_at_safepoint(true /* should_be_vm_thread */);
6403
6404 if (!free_list_only) {
6405 TearDownRegionSetsClosure cl(&_old_set);
6406 heap_region_iterate(&cl);
6407
6408 // Note that emptying the _young_list is postponed and instead done as
6409 // the first step when rebuilding the regions sets again. The reason for
6410 // this is that during a full GC string deduplication needs to know if
6411 // a collected region was young or old when the full GC was initiated.
6412 }
6413 _free_list.remove_all();
6414 }
6415
6416 class RebuildRegionSetsClosure : public HeapRegionClosure {
6417 private:
6418 bool _free_list_only;
6419 HeapRegionSet* _old_set;
6420 FreeRegionList* _free_list;
6421 size_t _total_used;
6422
6423 public:
6424 RebuildRegionSetsClosure(bool free_list_only,
6425 HeapRegionSet* old_set, FreeRegionList* free_list) :
6426 _free_list_only(free_list_only),
6427 _old_set(old_set), _free_list(free_list), _total_used(0) {
6428 assert(_free_list->is_empty(), "pre-condition");
6429 if (!free_list_only) {
6430 assert(_old_set->is_empty(), "pre-condition");
6431 }
6432 }
6433
6434 bool doHeapRegion(HeapRegion* r) {
6435 if (r->continuesHumongous()) {
6436 return false;
6437 }
6438
6439 if (r->is_empty()) {
6440 // Add free regions to the free list
6441 _free_list->add_as_tail(r);
6442 } else if (!_free_list_only) {
6443 assert(!r->is_young(), "we should not come across young regions");
6444
6445 if (r->isHumongous()) {
6446 // We ignore humongous regions, we left the humongous set unchanged
6447 } else {
6448 // The rest should be old, add them to the old set
6449 _old_set->add(r);
6450 }
6451 _total_used += r->used();
6452 }
6453
6454 return false;
6455 }
6456
6457 size_t total_used() {
6458 return _total_used;
6459 }
6460 };
6461
6462 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6463 assert_at_safepoint(true /* should_be_vm_thread */);
6464
6465 if (!free_list_only) {
6466 _young_list->empty_list();
6467 }
6468
6469 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6470 heap_region_iterate(&cl);
6471
6472 if (!free_list_only) {
6473 _summary_bytes_used = cl.total_used();
6474 }
6475 assert(_summary_bytes_used == recalculate_used(),
6476 err_msg("inconsistent _summary_bytes_used, "
6477 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6478 _summary_bytes_used, recalculate_used()));
6479 }
6480
6481 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6482 _refine_cte_cl->set_concurrent(concurrent);
6483 }
6484
6485 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6486 HeapRegion* hr = heap_region_containing(p);
6487 if (hr == NULL) {
6488 return false;
6489 } else {
6490 return hr->is_in(p);
6491 }
6492 }
6493
6494 // Methods for the mutator alloc region
6495
6496 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6497 bool force) {
6498 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6499 assert(!force || g1_policy()->can_expand_young_list(),
6500 "if force is true we should be able to expand the young list");
6501 bool young_list_full = g1_policy()->is_young_list_full();
6502 if (force || !young_list_full) {
6503 HeapRegion* new_alloc_region = new_region(word_size,
6504 false /* is_old */,
6505 false /* do_expand */);
6506 if (new_alloc_region != NULL) {
6507 set_region_short_lived_locked(new_alloc_region);
6508 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6509 return new_alloc_region;
6510 }
6511 }
6512 return NULL;
6513 }
6514
6515 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6516 size_t allocated_bytes) {
6517 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6518 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6519
6520 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6521 _summary_bytes_used += allocated_bytes;
6522 _hr_printer.retire(alloc_region);
6523 // We update the eden sizes here, when the region is retired,
6524 // instead of when it's allocated, since this is the point that its
6525 // used space has been recored in _summary_bytes_used.
6526 g1mm()->update_eden_size();
6527 }
6528
6529 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6530 bool force) {
6531 return _g1h->new_mutator_alloc_region(word_size, force);
6532 }
6533
6534 void G1CollectedHeap::set_par_threads() {
6535 // Don't change the number of workers. Use the value previously set
6536 // in the workgroup.
6537 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6538 uint n_workers = workers()->active_workers();
6539 assert(UseDynamicNumberOfGCThreads ||
6540 n_workers == workers()->total_workers(),
6541 "Otherwise should be using the total number of workers");
6542 if (n_workers == 0) {
6543 assert(false, "Should have been set in prior evacuation pause.");
6544 n_workers = ParallelGCThreads;
6545 workers()->set_active_workers(n_workers);
6546 }
6547 set_par_threads(n_workers);
6548 }
6549
6550 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6551 size_t allocated_bytes) {
6552 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6553 }
6554
6555 // Methods for the GC alloc regions
6556
6557 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6558 uint count,
6559 GCAllocPurpose ap) {
6560 assert(FreeList_lock->owned_by_self(), "pre-condition");
6561
6562 if (count < g1_policy()->max_regions(ap)) {
6563 bool survivor = (ap == GCAllocForSurvived);
6564 HeapRegion* new_alloc_region = new_region(word_size,
6565 !survivor,
6566 true /* do_expand */);
6567 if (new_alloc_region != NULL) {
6568 // We really only need to do this for old regions given that we
6569 // should never scan survivors. But it doesn't hurt to do it
6570 // for survivors too.
6571 new_alloc_region->set_saved_mark();
6572 if (survivor) {
6573 new_alloc_region->set_survivor();
6574 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6575 } else {
6576 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6577 }
6578 bool during_im = g1_policy()->during_initial_mark_pause();
6579 new_alloc_region->note_start_of_copying(during_im);
6580 return new_alloc_region;
6581 } else {
6582 g1_policy()->note_alloc_region_limit_reached(ap);
6583 }
6584 }
6585 return NULL;
6586 }
6587
6588 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6589 size_t allocated_bytes,
6590 GCAllocPurpose ap) {
6591 bool during_im = g1_policy()->during_initial_mark_pause();
6592 alloc_region->note_end_of_copying(during_im);
6593 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6594 if (ap == GCAllocForSurvived) {
6595 young_list()->add_survivor_region(alloc_region);
6596 } else {
6597 _old_set.add(alloc_region);
6598 }
6599 _hr_printer.retire(alloc_region);
6600 }
6601
6602 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6603 bool force) {
6604 assert(!force, "not supported for GC alloc regions");
6605 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6606 }
6607
6608 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6609 size_t allocated_bytes) {
6610 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6611 GCAllocForSurvived);
6612 }
6613
6614 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6615 bool force) {
6616 assert(!force, "not supported for GC alloc regions");
6617 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6618 }
6619
6620 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6621 size_t allocated_bytes) {
6622 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6623 GCAllocForTenured);
6624 }
6625 // Heap region set verification
6626
6627 class VerifyRegionListsClosure : public HeapRegionClosure {
6628 private:
6629 HeapRegionSet* _old_set;
6630 HeapRegionSet* _humongous_set;
6631 FreeRegionList* _free_list;
6632
6633 public:
6634 HeapRegionSetCount _old_count;
6635 HeapRegionSetCount _humongous_count;
6636 HeapRegionSetCount _free_count;
6637
6638 VerifyRegionListsClosure(HeapRegionSet* old_set,
6639 HeapRegionSet* humongous_set,
6640 FreeRegionList* free_list) :
6641 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6642 _old_count(), _humongous_count(), _free_count(){ }
6643
6644 bool doHeapRegion(HeapRegion* hr) {
6645 if (hr->continuesHumongous()) {
6646 return false;
6647 }
6648
6649 if (hr->is_young()) {
6650 // TODO
6651 } else if (hr->startsHumongous()) {
6652 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num()));
6653 _humongous_count.increment(1u, hr->capacity());
6654 } else if (hr->is_empty()) {
6655 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num()));
6656 _free_count.increment(1u, hr->capacity());
6657 } else {
6658 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num()));
6659 _old_count.increment(1u, hr->capacity());
6660 }
6661 return false;
6662 }
6663
6664 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6665 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6666 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6667 old_set->total_capacity_bytes(), _old_count.capacity()));
6668
6669 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6670 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6671 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6672
6673 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6674 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6675 free_list->total_capacity_bytes(), _free_count.capacity()));
6676 }
6677 };
6678
6679 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6680 HeapWord* bottom) {
6681 HeapWord* end = bottom + HeapRegion::GrainWords;
6682 MemRegion mr(bottom, end);
6683 assert(_g1_reserved.contains(mr), "invariant");
6684 // This might return NULL if the allocation fails
6685 return new HeapRegion(hrs_index, _bot_shared, mr);
6686 }
6687
6688 void G1CollectedHeap::verify_region_sets() {
6689 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6690
6691 // First, check the explicit lists.
6692 _free_list.verify_list();
6693 {
6694 // Given that a concurrent operation might be adding regions to
6695 // the secondary free list we have to take the lock before
6696 // verifying it.
6697 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6698 _secondary_free_list.verify_list();
6699 }
6700
6701 // If a concurrent region freeing operation is in progress it will
6702 // be difficult to correctly attributed any free regions we come
6703 // across to the correct free list given that they might belong to
6704 // one of several (free_list, secondary_free_list, any local lists,
6705 // etc.). So, if that's the case we will skip the rest of the
6706 // verification operation. Alternatively, waiting for the concurrent
6707 // operation to complete will have a non-trivial effect on the GC's
6708 // operation (no concurrent operation will last longer than the
6709 // interval between two calls to verification) and it might hide
6710 // any issues that we would like to catch during testing.
6711 if (free_regions_coming()) {
6712 return;
6713 }
6714
6715 // Make sure we append the secondary_free_list on the free_list so
6716 // that all free regions we will come across can be safely
6717 // attributed to the free_list.
6718 append_secondary_free_list_if_not_empty_with_lock();
6719
6720 // Finally, make sure that the region accounting in the lists is
6721 // consistent with what we see in the heap.
6722
6723 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6724 heap_region_iterate(&cl);
6725 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6726 }
6727
6728 // Optimized nmethod scanning
6729
6730 class RegisterNMethodOopClosure: public OopClosure {
6731 G1CollectedHeap* _g1h;
6732 nmethod* _nm;
6733
6734 template <class T> void do_oop_work(T* p) {
6735 T heap_oop = oopDesc::load_heap_oop(p);
6736 if (!oopDesc::is_null(heap_oop)) {
6737 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6738 HeapRegion* hr = _g1h->heap_region_containing(obj);
6739 assert(!hr->continuesHumongous(),
6740 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6741 " starting at "HR_FORMAT,
6742 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6743
6744 // HeapRegion::add_strong_code_root() avoids adding duplicate
6745 // entries but having duplicates is OK since we "mark" nmethods
6746 // as visited when we scan the strong code root lists during the GC.
6747 hr->add_strong_code_root(_nm);
6748 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6749 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6750 _nm, HR_FORMAT_PARAMS(hr)));
6751 }
6752 }
6753
6754 public:
6755 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6756 _g1h(g1h), _nm(nm) {}
6757
6758 void do_oop(oop* p) { do_oop_work(p); }
6759 void do_oop(narrowOop* p) { do_oop_work(p); }
6760 };
6761
6762 class UnregisterNMethodOopClosure: public OopClosure {
6763 G1CollectedHeap* _g1h;
6764 nmethod* _nm;
6765
6766 template <class T> void do_oop_work(T* p) {
6767 T heap_oop = oopDesc::load_heap_oop(p);
6768 if (!oopDesc::is_null(heap_oop)) {
6769 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6770 HeapRegion* hr = _g1h->heap_region_containing(obj);
6771 assert(!hr->continuesHumongous(),
6772 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6773 " starting at "HR_FORMAT,
6774 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6775
6776 hr->remove_strong_code_root(_nm);
6777 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6778 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6779 _nm, HR_FORMAT_PARAMS(hr)));
6780 }
6781 }
6782
6783 public:
6784 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6785 _g1h(g1h), _nm(nm) {}
6786
6787 void do_oop(oop* p) { do_oop_work(p); }
6788 void do_oop(narrowOop* p) { do_oop_work(p); }
6789 };
6790
6791 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6792 CollectedHeap::register_nmethod(nm);
6793
6794 guarantee(nm != NULL, "sanity");
6795 RegisterNMethodOopClosure reg_cl(this, nm);
6796 nm->oops_do(®_cl);
6797 }
6798
6799 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6800 CollectedHeap::unregister_nmethod(nm);
6801
6802 guarantee(nm != NULL, "sanity");
6803 UnregisterNMethodOopClosure reg_cl(this, nm);
6804 nm->oops_do(®_cl, true);
6805 }
6806
6807 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6808 public:
6809 bool doHeapRegion(HeapRegion *hr) {
6810 assert(!hr->isHumongous(),
6811 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6812 HR_FORMAT_PARAMS(hr)));
6813 hr->migrate_strong_code_roots();
6814 return false;
6815 }
6816 };
6817
6818 void G1CollectedHeap::migrate_strong_code_roots() {
6819 MigrateCodeRootsHeapRegionClosure cl;
6820 double migrate_start = os::elapsedTime();
6821 collection_set_iterate(&cl);
6822 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6823 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6824 }
6825
6826 void G1CollectedHeap::purge_code_root_memory() {
6827 double purge_start = os::elapsedTime();
6828 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6829 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6830 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6831 }
6832
6833 // Mark all the code roots that point into regions *not* in the
6834 // collection set.
6835 //
6836 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6837 // walking the the code roots lists of regions not in the collection
6838 // set. Suppose we have an nmethod (M) that points to objects in two
6839 // separate regions - one in the collection set (R1) and one not (R2).
6840 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6841 // nmethod M when walking the code roots for R1. When we come to scan
6842 // the code roots for R2, we would see that M is already marked and it
6843 // would be skipped and the objects in R2 that are referenced from M
6844 // would not be evacuated.
6845
6846 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6847
6848 class MarkStrongCodeRootOopClosure: public OopClosure {
6849 ConcurrentMark* _cm;
6850 HeapRegion* _hr;
6851 uint _worker_id;
6852
6853 template <class T> void do_oop_work(T* p) {
6854 T heap_oop = oopDesc::load_heap_oop(p);
6855 if (!oopDesc::is_null(heap_oop)) {
6856 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6857 // Only mark objects in the region (which is assumed
6858 // to be not in the collection set).
6859 if (_hr->is_in(obj)) {
6860 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6861 }
6862 }
6863 }
6864
6865 public:
6866 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6867 _cm(cm), _hr(hr), _worker_id(worker_id) {
6868 assert(!_hr->in_collection_set(), "sanity");
6869 }
6870
6871 void do_oop(narrowOop* p) { do_oop_work(p); }
6872 void do_oop(oop* p) { do_oop_work(p); }
6873 };
6874
6875 MarkStrongCodeRootOopClosure _oop_cl;
6876
6877 public:
6878 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6879 _oop_cl(cm, hr, worker_id) {}
6880
6881 void do_code_blob(CodeBlob* cb) {
6882 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6883 if (nm != NULL) {
6884 nm->oops_do(&_oop_cl);
6885 }
6886 }
6887 };
6888
6889 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6890 G1CollectedHeap* _g1h;
6891 uint _worker_id;
6892
6893 public:
6894 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6895 _g1h(g1h), _worker_id(worker_id) {}
6896
6897 bool doHeapRegion(HeapRegion *hr) {
6898 HeapRegionRemSet* hrrs = hr->rem_set();
6899 if (hr->continuesHumongous()) {
6900 // Code roots should never be attached to a continuation of a humongous region
6901 assert(hrrs->strong_code_roots_list_length() == 0,
6902 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6903 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6904 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6905 hrrs->strong_code_roots_list_length()));
6906 return false;
6907 }
6908
6909 if (hr->in_collection_set()) {
6910 // Don't mark code roots into regions in the collection set here.
6911 // They will be marked when we scan them.
6912 return false;
6913 }
6914
6915 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6916 hr->strong_code_roots_do(&cb_cl);
6917 return false;
6918 }
6919 };
6920
6921 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6922 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6923 if (G1CollectedHeap::use_parallel_gc_threads()) {
6924 heap_region_par_iterate_chunked(&cl,
6925 worker_id,
6926 workers()->active_workers(),
6927 HeapRegion::ParMarkRootClaimValue);
6928 } else {
6929 heap_region_iterate(&cl);
6930 }
6931 }
6932
6933 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6934 G1CollectedHeap* _g1h;
6935
6936 public:
6937 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6938 _g1h(g1h) {}
6939
6940 void do_code_blob(CodeBlob* cb) {
6941 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6942 if (nm == NULL) {
6943 return;
6944 }
6945
6946 if (ScavengeRootsInCode) {
6947 _g1h->register_nmethod(nm);
6948 }
6949 }
6950 };
6951
6952 void G1CollectedHeap::rebuild_strong_code_roots() {
6953 RebuildStrongCodeRootClosure blob_cl(this);
6954 CodeCache::blobs_do(&blob_cl);
6955 }