1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1YCTypes.hpp"
43 #include "gc_implementation/g1/heapRegion.inline.hpp"
44 #include "gc_implementation/g1/heapRegionRemSet.hpp"
45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
46 #include "gc_implementation/g1/vm_operations_g1.hpp"
47 #include "gc_implementation/shared/gcHeapSummary.hpp"
48 #include "gc_implementation/shared/gcTimer.hpp"
49 #include "gc_implementation/shared/gcTrace.hpp"
50 #include "gc_implementation/shared/gcTraceTime.hpp"
51 #include "gc_implementation/shared/isGCActiveMark.hpp"
52 #include "memory/gcLocker.inline.hpp"
53 #include "memory/generationSpec.hpp"
54 #include "memory/iterator.hpp"
55 #include "memory/referenceProcessor.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/oop.pcgc.inline.hpp"
58 #include "runtime/vmThread.hpp"
59 #include "utilities/ticks.hpp"
60
61 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
62
63 // turn it on so that the contents of the young list (scan-only /
64 // to-be-collected) are printed at "strategic" points before / during
65 // / after the collection --- this is useful for debugging
66 #define YOUNG_LIST_VERBOSE 0
67 // CURRENT STATUS
68 // This file is under construction. Search for "FIXME".
69
70 // INVARIANTS/NOTES
71 //
72 // All allocation activity covered by the G1CollectedHeap interface is
73 // serialized by acquiring the HeapLock. This happens in mem_allocate
74 // and allocate_new_tlab, which are the "entry" points to the
75 // allocation code from the rest of the JVM. (Note that this does not
76 // apply to TLAB allocation, which is not part of this interface: it
77 // is done by clients of this interface.)
78
79 // Notes on implementation of parallelism in different tasks.
80 //
81 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
82 // The number of GC workers is passed to heap_region_par_iterate_chunked().
83 // It does use run_task() which sets _n_workers in the task.
84 // G1ParTask executes g1_process_strong_roots() ->
85 // SharedHeap::process_strong_roots() which calls eventually to
86 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
87 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
88 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
89 //
90
91 // Local to this file.
92
93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
94 SuspendibleThreadSet* _sts;
95 G1RemSet* _g1rs;
96 ConcurrentG1Refine* _cg1r;
97 bool _concurrent;
98 public:
99 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
100 G1RemSet* g1rs,
101 ConcurrentG1Refine* cg1r) :
102 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
103 {}
104 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
105 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
106 // This path is executed by the concurrent refine or mutator threads,
107 // concurrently, and so we do not care if card_ptr contains references
108 // that point into the collection set.
109 assert(!oops_into_cset, "should be");
110
111 if (_concurrent && _sts->should_yield()) {
112 // Caller will actually yield.
113 return false;
114 }
115 // Otherwise, we finished successfully; return true.
116 return true;
117 }
118 void set_concurrent(bool b) { _concurrent = b; }
119 };
120
121
122 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
123 int _calls;
124 G1CollectedHeap* _g1h;
125 CardTableModRefBS* _ctbs;
126 int _histo[256];
127 public:
128 ClearLoggedCardTableEntryClosure() :
129 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
130 {
131 for (int i = 0; i < 256; i++) _histo[i] = 0;
132 }
133 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
134 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
135 _calls++;
136 unsigned char* ujb = (unsigned char*)card_ptr;
137 int ind = (int)(*ujb);
138 _histo[ind]++;
139 *card_ptr = -1;
140 }
141 return true;
142 }
143 int calls() { return _calls; }
144 void print_histo() {
145 gclog_or_tty->print_cr("Card table value histogram:");
146 for (int i = 0; i < 256; i++) {
147 if (_histo[i] != 0) {
148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
149 }
150 }
151 }
152 };
153
154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
155 int _calls;
156 G1CollectedHeap* _g1h;
157 CardTableModRefBS* _ctbs;
158 public:
159 RedirtyLoggedCardTableEntryClosure() :
160 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
161
162 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
163 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
164 _calls++;
165 *card_ptr = 0;
166 }
167 return true;
168 }
169 int calls() { return _calls; }
170 };
171
172 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
173 public:
174 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
175 *card_ptr = CardTableModRefBS::dirty_card_val();
176 return true;
177 }
178 };
179
180 YoungList::YoungList(G1CollectedHeap* g1h) :
181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
183 guarantee(check_list_empty(false), "just making sure...");
184 }
185
186 void YoungList::push_region(HeapRegion *hr) {
187 assert(!hr->is_young(), "should not already be young");
188 assert(hr->get_next_young_region() == NULL, "cause it should!");
189
190 hr->set_next_young_region(_head);
191 _head = hr;
192
193 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
194 ++_length;
195 }
196
197 void YoungList::add_survivor_region(HeapRegion* hr) {
198 assert(hr->is_survivor(), "should be flagged as survivor region");
199 assert(hr->get_next_young_region() == NULL, "cause it should!");
200
201 hr->set_next_young_region(_survivor_head);
202 if (_survivor_head == NULL) {
203 _survivor_tail = hr;
204 }
205 _survivor_head = hr;
206 ++_survivor_length;
207 }
208
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 list->set_not_young();
215 list = next;
216 }
217 }
218
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
221
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
225
226 empty_list(_survivor_head);
227 _survivor_head = NULL;
228 _survivor_tail = NULL;
229 _survivor_length = 0;
230
231 _last_sampled_rs_lengths = 0;
232
233 assert(check_list_empty(false), "just making sure...");
234 }
235
236 bool YoungList::check_list_well_formed() {
237 bool ret = true;
238
239 uint length = 0;
240 HeapRegion* curr = _head;
241 HeapRegion* last = NULL;
242 while (curr != NULL) {
243 if (!curr->is_young()) {
244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
245 "incorrectly tagged (y: %d, surv: %d)",
246 curr->bottom(), curr->end(),
247 curr->is_young(), curr->is_survivor());
248 ret = false;
249 }
250 ++length;
251 last = curr;
252 curr = curr->get_next_young_region();
253 }
254 ret = ret && (length == _length);
255
256 if (!ret) {
257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
258 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
259 length, _length);
260 }
261
262 return ret;
263 }
264
265 bool YoungList::check_list_empty(bool check_sample) {
266 bool ret = true;
267
268 if (_length != 0) {
269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
270 _length);
271 ret = false;
272 }
273 if (check_sample && _last_sampled_rs_lengths != 0) {
274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
275 ret = false;
276 }
277 if (_head != NULL) {
278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
279 ret = false;
280 }
281 if (!ret) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
283 }
284
285 return ret;
286 }
287
288 void
289 YoungList::rs_length_sampling_init() {
290 _sampled_rs_lengths = 0;
291 _curr = _head;
292 }
293
294 bool
295 YoungList::rs_length_sampling_more() {
296 return _curr != NULL;
297 }
298
299 void
300 YoungList::rs_length_sampling_next() {
301 assert( _curr != NULL, "invariant" );
302 size_t rs_length = _curr->rem_set()->occupied();
303
304 _sampled_rs_lengths += rs_length;
305
306 // The current region may not yet have been added to the
307 // incremental collection set (it gets added when it is
308 // retired as the current allocation region).
309 if (_curr->in_collection_set()) {
310 // Update the collection set policy information for this region
311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
312 }
313
314 _curr = _curr->get_next_young_region();
315 if (_curr == NULL) {
316 _last_sampled_rs_lengths = _sampled_rs_lengths;
317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
318 }
319 }
320
321 void
322 YoungList::reset_auxilary_lists() {
323 guarantee( is_empty(), "young list should be empty" );
324 assert(check_list_well_formed(), "young list should be well formed");
325
326 // Add survivor regions to SurvRateGroup.
327 _g1h->g1_policy()->note_start_adding_survivor_regions();
328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
329
330 int young_index_in_cset = 0;
331 for (HeapRegion* curr = _survivor_head;
332 curr != NULL;
333 curr = curr->get_next_young_region()) {
334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
335
336 // The region is a non-empty survivor so let's add it to
337 // the incremental collection set for the next evacuation
338 // pause.
339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
340 young_index_in_cset += 1;
341 }
342 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
343 _g1h->g1_policy()->note_stop_adding_survivor_regions();
344
345 _head = _survivor_head;
346 _length = _survivor_length;
347 if (_survivor_head != NULL) {
348 assert(_survivor_tail != NULL, "cause it shouldn't be");
349 assert(_survivor_length > 0, "invariant");
350 _survivor_tail->set_next_young_region(NULL);
351 }
352
353 // Don't clear the survivor list handles until the start of
354 // the next evacuation pause - we need it in order to re-tag
355 // the survivor regions from this evacuation pause as 'young'
356 // at the start of the next.
357
358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
359
360 assert(check_list_well_formed(), "young list should be well formed");
361 }
362
363 void YoungList::print() {
364 HeapRegion* lists[] = {_head, _survivor_head};
365 const char* names[] = {"YOUNG", "SURVIVOR"};
366
367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
369 HeapRegion *curr = lists[list];
370 if (curr == NULL)
371 gclog_or_tty->print_cr(" empty");
372 while (curr != NULL) {
373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
374 HR_FORMAT_PARAMS(curr),
375 curr->prev_top_at_mark_start(),
376 curr->next_top_at_mark_start(),
377 curr->age_in_surv_rate_group_cond());
378 curr = curr->get_next_young_region();
379 }
380 }
381
382 gclog_or_tty->print_cr("");
383 }
384
385 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
386 {
387 // Claim the right to put the region on the dirty cards region list
388 // by installing a self pointer.
389 HeapRegion* next = hr->get_next_dirty_cards_region();
390 if (next == NULL) {
391 HeapRegion* res = (HeapRegion*)
392 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
393 NULL);
394 if (res == NULL) {
395 HeapRegion* head;
396 do {
397 // Put the region to the dirty cards region list.
398 head = _dirty_cards_region_list;
399 next = (HeapRegion*)
400 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
401 if (next == head) {
402 assert(hr->get_next_dirty_cards_region() == hr,
403 "hr->get_next_dirty_cards_region() != hr");
404 if (next == NULL) {
405 // The last region in the list points to itself.
406 hr->set_next_dirty_cards_region(hr);
407 } else {
408 hr->set_next_dirty_cards_region(next);
409 }
410 }
411 } while (next != head);
412 }
413 }
414 }
415
416 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
417 {
418 HeapRegion* head;
419 HeapRegion* hr;
420 do {
421 head = _dirty_cards_region_list;
422 if (head == NULL) {
423 return NULL;
424 }
425 HeapRegion* new_head = head->get_next_dirty_cards_region();
426 if (head == new_head) {
427 // The last region.
428 new_head = NULL;
429 }
430 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
431 head);
432 } while (hr != head);
433 assert(hr != NULL, "invariant");
434 hr->set_next_dirty_cards_region(NULL);
435 return hr;
436 }
437
438 void G1CollectedHeap::stop_conc_gc_threads() {
439 _cg1r->stop();
440 _cmThread->stop();
441 }
442
443 #ifdef ASSERT
444 // A region is added to the collection set as it is retired
445 // so an address p can point to a region which will be in the
446 // collection set but has not yet been retired. This method
447 // therefore is only accurate during a GC pause after all
448 // regions have been retired. It is used for debugging
449 // to check if an nmethod has references to objects that can
450 // be move during a partial collection. Though it can be
451 // inaccurate, it is sufficient for G1 because the conservative
452 // implementation of is_scavengable() for G1 will indicate that
453 // all nmethods must be scanned during a partial collection.
454 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
455 HeapRegion* hr = heap_region_containing(p);
456 return hr != NULL && hr->in_collection_set();
457 }
458 #endif
459
460 // Returns true if the reference points to an object that
461 // can move in an incremental collection.
462 bool G1CollectedHeap::is_scavengable(const void* p) {
463 G1CollectedHeap* g1h = G1CollectedHeap::heap();
464 G1CollectorPolicy* g1p = g1h->g1_policy();
465 HeapRegion* hr = heap_region_containing(p);
466 if (hr == NULL) {
467 // null
468 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
469 return false;
470 } else {
471 return !hr->isHumongous();
472 }
473 }
474
475 void G1CollectedHeap::check_ct_logs_at_safepoint() {
476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
477 CardTableModRefBS* ct_bs = g1_barrier_set();
478
479 // Count the dirty cards at the start.
480 CountNonCleanMemRegionClosure count1(this);
481 ct_bs->mod_card_iterate(&count1);
482 int orig_count = count1.n();
483
484 // First clear the logged cards.
485 ClearLoggedCardTableEntryClosure clear;
486 dcqs.set_closure(&clear);
487 dcqs.apply_closure_to_all_completed_buffers();
488 dcqs.iterate_closure_all_threads(false);
489 clear.print_histo();
490
491 // Now ensure that there's no dirty cards.
492 CountNonCleanMemRegionClosure count2(this);
493 ct_bs->mod_card_iterate(&count2);
494 if (count2.n() != 0) {
495 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
496 count2.n(), orig_count);
497 }
498 guarantee(count2.n() == 0, "Card table should be clean.");
499
500 RedirtyLoggedCardTableEntryClosure redirty;
501 JavaThread::dirty_card_queue_set().set_closure(&redirty);
502 dcqs.apply_closure_to_all_completed_buffers();
503 dcqs.iterate_closure_all_threads(false);
504 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
505 clear.calls(), orig_count);
506 guarantee(redirty.calls() == clear.calls(),
507 "Or else mechanism is broken.");
508
509 CountNonCleanMemRegionClosure count3(this);
510 ct_bs->mod_card_iterate(&count3);
511 if (count3.n() != orig_count) {
512 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
513 orig_count, count3.n());
514 guarantee(count3.n() >= orig_count, "Should have restored them all.");
515 }
516
517 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
518 }
519
520 // Private class members.
521
522 G1CollectedHeap* G1CollectedHeap::_g1h;
523
524 // Private methods.
525
526 HeapRegion*
527 G1CollectedHeap::new_region_try_secondary_free_list() {
528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
529 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
530 if (!_secondary_free_list.is_empty()) {
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "secondary_free_list has %u entries",
534 _secondary_free_list.length());
535 }
536 // It looks as if there are free regions available on the
537 // secondary_free_list. Let's move them to the free_list and try
538 // again to allocate from it.
539 append_secondary_free_list();
540
541 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
542 "empty we should have moved at least one entry to the free_list");
543 HeapRegion* res = _free_list.remove_head();
544 if (G1ConcRegionFreeingVerbose) {
545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
546 "allocated "HR_FORMAT" from secondary_free_list",
547 HR_FORMAT_PARAMS(res));
548 }
549 return res;
550 }
551
552 // Wait here until we get notified either when (a) there are no
553 // more free regions coming or (b) some regions have been moved on
554 // the secondary_free_list.
555 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
556 }
557
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "could not allocate from secondary_free_list");
561 }
562 return NULL;
563 }
564
565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
566 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
567 "the only time we use this to allocate a humongous region is "
568 "when we are allocating a single humongous region");
569
570 HeapRegion* res;
571 if (G1StressConcRegionFreeing) {
572 if (!_secondary_free_list.is_empty()) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "forced to look at the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list();
578 if (res != NULL) {
579 return res;
580 }
581 }
582 }
583 res = _free_list.remove_head_or_null();
584 if (res == NULL) {
585 if (G1ConcRegionFreeingVerbose) {
586 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
587 "res == NULL, trying the secondary_free_list");
588 }
589 res = new_region_try_secondary_free_list();
590 }
591 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
592 // Currently, only attempts to allocate GC alloc regions set
593 // do_expand to true. So, we should only reach here during a
594 // safepoint. If this assumption changes we might have to
595 // reconsider the use of _expand_heap_after_alloc_failure.
596 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
597
598 ergo_verbose1(ErgoHeapSizing,
599 "attempt heap expansion",
600 ergo_format_reason("region allocation request failed")
601 ergo_format_byte("allocation request"),
602 word_size * HeapWordSize);
603 if (expand(word_size * HeapWordSize)) {
604 // Given that expand() succeeded in expanding the heap, and we
605 // always expand the heap by an amount aligned to the heap
606 // region size, the free list should in theory not be empty. So
607 // it would probably be OK to use remove_head(). But the extra
608 // check for NULL is unlikely to be a performance issue here (we
609 // just expanded the heap!) so let's just be conservative and
610 // use remove_head_or_null().
611 res = _free_list.remove_head_or_null();
612 } else {
613 _expand_heap_after_alloc_failure = false;
614 }
615 }
616 return res;
617 }
618
619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
620 size_t word_size) {
621 assert(isHumongous(word_size), "word_size should be humongous");
622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
623
624 uint first = G1_NULL_HRS_INDEX;
625 if (num_regions == 1) {
626 // Only one region to allocate, no need to go through the slower
627 // path. The caller will attempt the expansion if this fails, so
628 // let's not try to expand here too.
629 HeapRegion* hr = new_region(word_size, false /* do_expand */);
630 if (hr != NULL) {
631 first = hr->hrs_index();
632 } else {
633 first = G1_NULL_HRS_INDEX;
634 }
635 } else {
636 // We can't allocate humongous regions while cleanupComplete() is
637 // running, since some of the regions we find to be empty might not
638 // yet be added to the free list and it is not straightforward to
639 // know which list they are on so that we can remove them. Note
640 // that we only need to do this if we need to allocate more than
641 // one region to satisfy the current humongous allocation
642 // request. If we are only allocating one region we use the common
643 // region allocation code (see above).
644 wait_while_free_regions_coming();
645 append_secondary_free_list_if_not_empty_with_lock();
646
647 if (free_regions() >= num_regions) {
648 first = _hrs.find_contiguous(num_regions);
649 if (first != G1_NULL_HRS_INDEX) {
650 for (uint i = first; i < first + num_regions; ++i) {
651 HeapRegion* hr = region_at(i);
652 assert(hr->is_empty(), "sanity");
653 assert(is_on_master_free_list(hr), "sanity");
654 hr->set_pending_removal(true);
655 }
656 _free_list.remove_all_pending(num_regions);
657 }
658 }
659 }
660 return first;
661 }
662
663 HeapWord*
664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
665 uint num_regions,
666 size_t word_size) {
667 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
668 assert(isHumongous(word_size), "word_size should be humongous");
669 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
670
671 // Index of last region in the series + 1.
672 uint last = first + num_regions;
673
674 // We need to initialize the region(s) we just discovered. This is
675 // a bit tricky given that it can happen concurrently with
676 // refinement threads refining cards on these regions and
677 // potentially wanting to refine the BOT as they are scanning
678 // those cards (this can happen shortly after a cleanup; see CR
679 // 6991377). So we have to set up the region(s) carefully and in
680 // a specific order.
681
682 // The word size sum of all the regions we will allocate.
683 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
684 assert(word_size <= word_size_sum, "sanity");
685
686 // This will be the "starts humongous" region.
687 HeapRegion* first_hr = region_at(first);
688 // The header of the new object will be placed at the bottom of
689 // the first region.
690 HeapWord* new_obj = first_hr->bottom();
691 // This will be the new end of the first region in the series that
692 // should also match the end of the last region in the series.
693 HeapWord* new_end = new_obj + word_size_sum;
694 // This will be the new top of the first region that will reflect
695 // this allocation.
696 HeapWord* new_top = new_obj + word_size;
697
698 // First, we need to zero the header of the space that we will be
699 // allocating. When we update top further down, some refinement
700 // threads might try to scan the region. By zeroing the header we
701 // ensure that any thread that will try to scan the region will
702 // come across the zero klass word and bail out.
703 //
704 // NOTE: It would not have been correct to have used
705 // CollectedHeap::fill_with_object() and make the space look like
706 // an int array. The thread that is doing the allocation will
707 // later update the object header to a potentially different array
708 // type and, for a very short period of time, the klass and length
709 // fields will be inconsistent. This could cause a refinement
710 // thread to calculate the object size incorrectly.
711 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
712
713 // We will set up the first region as "starts humongous". This
714 // will also update the BOT covering all the regions to reflect
715 // that there is a single object that starts at the bottom of the
716 // first region.
717 first_hr->set_startsHumongous(new_top, new_end);
718
719 // Then, if there are any, we will set up the "continues
720 // humongous" regions.
721 HeapRegion* hr = NULL;
722 for (uint i = first + 1; i < last; ++i) {
723 hr = region_at(i);
724 hr->set_continuesHumongous(first_hr);
725 }
726 // If we have "continues humongous" regions (hr != NULL), then the
727 // end of the last one should match new_end.
728 assert(hr == NULL || hr->end() == new_end, "sanity");
729
730 // Up to this point no concurrent thread would have been able to
731 // do any scanning on any region in this series. All the top
732 // fields still point to bottom, so the intersection between
733 // [bottom,top] and [card_start,card_end] will be empty. Before we
734 // update the top fields, we'll do a storestore to make sure that
735 // no thread sees the update to top before the zeroing of the
736 // object header and the BOT initialization.
737 OrderAccess::storestore();
738
739 // Now that the BOT and the object header have been initialized,
740 // we can update top of the "starts humongous" region.
741 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
742 "new_top should be in this region");
743 first_hr->set_top(new_top);
744 if (_hr_printer.is_active()) {
745 HeapWord* bottom = first_hr->bottom();
746 HeapWord* end = first_hr->orig_end();
747 if ((first + 1) == last) {
748 // the series has a single humongous region
749 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
750 } else {
751 // the series has more than one humongous regions
752 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
753 }
754 }
755
756 // Now, we will update the top fields of the "continues humongous"
757 // regions. The reason we need to do this is that, otherwise,
758 // these regions would look empty and this will confuse parts of
759 // G1. For example, the code that looks for a consecutive number
760 // of empty regions will consider them empty and try to
761 // re-allocate them. We can extend is_empty() to also include
762 // !continuesHumongous(), but it is easier to just update the top
763 // fields here. The way we set top for all regions (i.e., top ==
764 // end for all regions but the last one, top == new_top for the
765 // last one) is actually used when we will free up the humongous
766 // region in free_humongous_region().
767 hr = NULL;
768 for (uint i = first + 1; i < last; ++i) {
769 hr = region_at(i);
770 if ((i + 1) == last) {
771 // last continues humongous region
772 assert(hr->bottom() < new_top && new_top <= hr->end(),
773 "new_top should fall on this region");
774 hr->set_top(new_top);
775 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
776 } else {
777 // not last one
778 assert(new_top > hr->end(), "new_top should be above this region");
779 hr->set_top(hr->end());
780 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
781 }
782 }
783 // If we have continues humongous regions (hr != NULL), then the
784 // end of the last one should match new_end and its top should
785 // match new_top.
786 assert(hr == NULL ||
787 (hr->end() == new_end && hr->top() == new_top), "sanity");
788
789 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
790 _summary_bytes_used += first_hr->used();
791 _humongous_set.add(first_hr);
792
793 return new_obj;
794 }
795
796 // If could fit into free regions w/o expansion, try.
797 // Otherwise, if can expand, do so.
798 // Otherwise, if using ex regions might help, try with ex given back.
799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
800 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
801
802 verify_region_sets_optional();
803
804 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
805 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
806 uint x_num = expansion_regions();
807 uint fs = _hrs.free_suffix();
808 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
809 if (first == G1_NULL_HRS_INDEX) {
810 // The only thing we can do now is attempt expansion.
811 if (fs + x_num >= num_regions) {
812 // If the number of regions we're trying to allocate for this
813 // object is at most the number of regions in the free suffix,
814 // then the call to humongous_obj_allocate_find_first() above
815 // should have succeeded and we wouldn't be here.
816 //
817 // We should only be trying to expand when the free suffix is
818 // not sufficient for the object _and_ we have some expansion
819 // room available.
820 assert(num_regions > fs, "earlier allocation should have succeeded");
821
822 ergo_verbose1(ErgoHeapSizing,
823 "attempt heap expansion",
824 ergo_format_reason("humongous allocation request failed")
825 ergo_format_byte("allocation request"),
826 word_size * HeapWordSize);
827 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
828 // Even though the heap was expanded, it might not have
829 // reached the desired size. So, we cannot assume that the
830 // allocation will succeed.
831 first = humongous_obj_allocate_find_first(num_regions, word_size);
832 }
833 }
834 }
835
836 HeapWord* result = NULL;
837 if (first != G1_NULL_HRS_INDEX) {
838 result =
839 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
840 assert(result != NULL, "it should always return a valid result");
841
842 // A successful humongous object allocation changes the used space
843 // information of the old generation so we need to recalculate the
844 // sizes and update the jstat counters here.
845 g1mm()->update_sizes();
846 }
847
848 verify_region_sets_optional();
849
850 return result;
851 }
852
853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
856
857 unsigned int dummy_gc_count_before;
858 int dummy_gclocker_retry_count = 0;
859 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
860 }
861
862 HeapWord*
863 G1CollectedHeap::mem_allocate(size_t word_size,
864 bool* gc_overhead_limit_was_exceeded) {
865 assert_heap_not_locked_and_not_at_safepoint();
866
867 // Loop until the allocation is satisfied, or unsatisfied after GC.
868 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
869 unsigned int gc_count_before;
870
871 HeapWord* result = NULL;
872 if (!isHumongous(word_size)) {
873 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
874 } else {
875 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
876 }
877 if (result != NULL) {
878 return result;
879 }
880
881 // Create the garbage collection operation...
882 VM_G1CollectForAllocation op(gc_count_before, word_size);
883 // ...and get the VM thread to execute it.
884 VMThread::execute(&op);
885
886 if (op.prologue_succeeded() && op.pause_succeeded()) {
887 // If the operation was successful we'll return the result even
888 // if it is NULL. If the allocation attempt failed immediately
889 // after a Full GC, it's unlikely we'll be able to allocate now.
890 HeapWord* result = op.result();
891 if (result != NULL && !isHumongous(word_size)) {
892 // Allocations that take place on VM operations do not do any
893 // card dirtying and we have to do it here. We only have to do
894 // this for non-humongous allocations, though.
895 dirty_young_block(result, word_size);
896 }
897 return result;
898 } else {
899 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
900 return NULL;
901 }
902 assert(op.result() == NULL,
903 "the result should be NULL if the VM op did not succeed");
904 }
905
906 // Give a warning if we seem to be looping forever.
907 if ((QueuedAllocationWarningCount > 0) &&
908 (try_count % QueuedAllocationWarningCount == 0)) {
909 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
910 }
911 }
912
913 ShouldNotReachHere();
914 return NULL;
915 }
916
917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
918 unsigned int *gc_count_before_ret,
919 int* gclocker_retry_count_ret) {
920 // Make sure you read the note in attempt_allocation_humongous().
921
922 assert_heap_not_locked_and_not_at_safepoint();
923 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
924 "be called for humongous allocation requests");
925
926 // We should only get here after the first-level allocation attempt
927 // (attempt_allocation()) failed to allocate.
928
929 // We will loop until a) we manage to successfully perform the
930 // allocation or b) we successfully schedule a collection which
931 // fails to perform the allocation. b) is the only case when we'll
932 // return NULL.
933 HeapWord* result = NULL;
934 for (int try_count = 1; /* we'll return */; try_count += 1) {
935 bool should_try_gc;
936 unsigned int gc_count_before;
937
938 {
939 MutexLockerEx x(Heap_lock);
940
941 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
942 false /* bot_updates */);
943 if (result != NULL) {
944 return result;
945 }
946
947 // If we reach here, attempt_allocation_locked() above failed to
948 // allocate a new region. So the mutator alloc region should be NULL.
949 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
950
951 if (GC_locker::is_active_and_needs_gc()) {
952 if (g1_policy()->can_expand_young_list()) {
953 // No need for an ergo verbose message here,
954 // can_expand_young_list() does this when it returns true.
955 result = _mutator_alloc_region.attempt_allocation_force(word_size,
956 false /* bot_updates */);
957 if (result != NULL) {
958 return result;
959 }
960 }
961 should_try_gc = false;
962 } else {
963 // The GCLocker may not be active but the GCLocker initiated
964 // GC may not yet have been performed (GCLocker::needs_gc()
965 // returns true). In this case we do not try this GC and
966 // wait until the GCLocker initiated GC is performed, and
967 // then retry the allocation.
968 if (GC_locker::needs_gc()) {
969 should_try_gc = false;
970 } else {
971 // Read the GC count while still holding the Heap_lock.
972 gc_count_before = total_collections();
973 should_try_gc = true;
974 }
975 }
976 }
977
978 if (should_try_gc) {
979 bool succeeded;
980 result = do_collection_pause(word_size, gc_count_before, &succeeded,
981 GCCause::_g1_inc_collection_pause);
982 if (result != NULL) {
983 assert(succeeded, "only way to get back a non-NULL result");
984 return result;
985 }
986
987 if (succeeded) {
988 // If we get here we successfully scheduled a collection which
989 // failed to allocate. No point in trying to allocate
990 // further. We'll just return NULL.
991 MutexLockerEx x(Heap_lock);
992 *gc_count_before_ret = total_collections();
993 return NULL;
994 }
995 } else {
996 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
997 MutexLockerEx x(Heap_lock);
998 *gc_count_before_ret = total_collections();
999 return NULL;
1000 }
1001 // The GCLocker is either active or the GCLocker initiated
1002 // GC has not yet been performed. Stall until it is and
1003 // then retry the allocation.
1004 GC_locker::stall_until_clear();
1005 (*gclocker_retry_count_ret) += 1;
1006 }
1007
1008 // We can reach here if we were unsuccessful in scheduling a
1009 // collection (because another thread beat us to it) or if we were
1010 // stalled due to the GC locker. In either can we should retry the
1011 // allocation attempt in case another thread successfully
1012 // performed a collection and reclaimed enough space. We do the
1013 // first attempt (without holding the Heap_lock) here and the
1014 // follow-on attempt will be at the start of the next loop
1015 // iteration (after taking the Heap_lock).
1016 result = _mutator_alloc_region.attempt_allocation(word_size,
1017 false /* bot_updates */);
1018 if (result != NULL) {
1019 return result;
1020 }
1021
1022 // Give a warning if we seem to be looping forever.
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_slow() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1035 unsigned int * gc_count_before_ret,
1036 int* gclocker_retry_count_ret) {
1037 // The structure of this method has a lot of similarities to
1038 // attempt_allocation_slow(). The reason these two were not merged
1039 // into a single one is that such a method would require several "if
1040 // allocation is not humongous do this, otherwise do that"
1041 // conditional paths which would obscure its flow. In fact, an early
1042 // version of this code did use a unified method which was harder to
1043 // follow and, as a result, it had subtle bugs that were hard to
1044 // track down. So keeping these two methods separate allows each to
1045 // be more readable. It will be good to keep these two in sync as
1046 // much as possible.
1047
1048 assert_heap_not_locked_and_not_at_safepoint();
1049 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1050 "should only be called for humongous allocations");
1051
1052 // Humongous objects can exhaust the heap quickly, so we should check if we
1053 // need to start a marking cycle at each humongous object allocation. We do
1054 // the check before we do the actual allocation. The reason for doing it
1055 // before the allocation is that we avoid having to keep track of the newly
1056 // allocated memory while we do a GC.
1057 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1058 word_size)) {
1059 collect(GCCause::_g1_humongous_allocation);
1060 }
1061
1062 // We will loop until a) we manage to successfully perform the
1063 // allocation or b) we successfully schedule a collection which
1064 // fails to perform the allocation. b) is the only case when we'll
1065 // return NULL.
1066 HeapWord* result = NULL;
1067 for (int try_count = 1; /* we'll return */; try_count += 1) {
1068 bool should_try_gc;
1069 unsigned int gc_count_before;
1070
1071 {
1072 MutexLockerEx x(Heap_lock);
1073
1074 // Given that humongous objects are not allocated in young
1075 // regions, we'll first try to do the allocation without doing a
1076 // collection hoping that there's enough space in the heap.
1077 result = humongous_obj_allocate(word_size);
1078 if (result != NULL) {
1079 return result;
1080 }
1081
1082 if (GC_locker::is_active_and_needs_gc()) {
1083 should_try_gc = false;
1084 } else {
1085 // The GCLocker may not be active but the GCLocker initiated
1086 // GC may not yet have been performed (GCLocker::needs_gc()
1087 // returns true). In this case we do not try this GC and
1088 // wait until the GCLocker initiated GC is performed, and
1089 // then retry the allocation.
1090 if (GC_locker::needs_gc()) {
1091 should_try_gc = false;
1092 } else {
1093 // Read the GC count while still holding the Heap_lock.
1094 gc_count_before = total_collections();
1095 should_try_gc = true;
1096 }
1097 }
1098 }
1099
1100 if (should_try_gc) {
1101 // If we failed to allocate the humongous object, we should try to
1102 // do a collection pause (if we're allowed) in case it reclaims
1103 // enough space for the allocation to succeed after the pause.
1104
1105 bool succeeded;
1106 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1107 GCCause::_g1_humongous_allocation);
1108 if (result != NULL) {
1109 assert(succeeded, "only way to get back a non-NULL result");
1110 return result;
1111 }
1112
1113 if (succeeded) {
1114 // If we get here we successfully scheduled a collection which
1115 // failed to allocate. No point in trying to allocate
1116 // further. We'll just return NULL.
1117 MutexLockerEx x(Heap_lock);
1118 *gc_count_before_ret = total_collections();
1119 return NULL;
1120 }
1121 } else {
1122 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1123 MutexLockerEx x(Heap_lock);
1124 *gc_count_before_ret = total_collections();
1125 return NULL;
1126 }
1127 // The GCLocker is either active or the GCLocker initiated
1128 // GC has not yet been performed. Stall until it is and
1129 // then retry the allocation.
1130 GC_locker::stall_until_clear();
1131 (*gclocker_retry_count_ret) += 1;
1132 }
1133
1134 // We can reach here if we were unsuccessful in scheduling a
1135 // collection (because another thread beat us to it) or if we were
1136 // stalled due to the GC locker. In either can we should retry the
1137 // allocation attempt in case another thread successfully
1138 // performed a collection and reclaimed enough space. Give a
1139 // warning if we seem to be looping forever.
1140
1141 if ((QueuedAllocationWarningCount > 0) &&
1142 (try_count % QueuedAllocationWarningCount == 0)) {
1143 warning("G1CollectedHeap::attempt_allocation_humongous() "
1144 "retries %d times", try_count);
1145 }
1146 }
1147
1148 ShouldNotReachHere();
1149 return NULL;
1150 }
1151
1152 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1153 bool expect_null_mutator_alloc_region) {
1154 assert_at_safepoint(true /* should_be_vm_thread */);
1155 assert(_mutator_alloc_region.get() == NULL ||
1156 !expect_null_mutator_alloc_region,
1157 "the current alloc region was unexpectedly found to be non-NULL");
1158
1159 if (!isHumongous(word_size)) {
1160 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1161 false /* bot_updates */);
1162 } else {
1163 HeapWord* result = humongous_obj_allocate(word_size);
1164 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1165 g1_policy()->set_initiate_conc_mark_if_possible();
1166 }
1167 return result;
1168 }
1169
1170 ShouldNotReachHere();
1171 }
1172
1173 class PostMCRemSetClearClosure: public HeapRegionClosure {
1174 G1CollectedHeap* _g1h;
1175 ModRefBarrierSet* _mr_bs;
1176 public:
1177 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1178 _g1h(g1h), _mr_bs(mr_bs) {}
1179
1180 bool doHeapRegion(HeapRegion* r) {
1181 HeapRegionRemSet* hrrs = r->rem_set();
1182
1183 if (r->continuesHumongous()) {
1184 // We'll assert that the strong code root list and RSet is empty
1185 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1186 assert(hrrs->occupied() == 0, "RSet should be empty");
1187 return false;
1188 }
1189
1190 _g1h->reset_gc_time_stamps(r);
1191 hrrs->clear();
1192 // You might think here that we could clear just the cards
1193 // corresponding to the used region. But no: if we leave a dirty card
1194 // in a region we might allocate into, then it would prevent that card
1195 // from being enqueued, and cause it to be missed.
1196 // Re: the performance cost: we shouldn't be doing full GC anyway!
1197 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1198
1199 return false;
1200 }
1201 };
1202
1203 void G1CollectedHeap::clear_rsets_post_compaction() {
1204 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1205 heap_region_iterate(&rs_clear);
1206 }
1207
1208 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1209 G1CollectedHeap* _g1h;
1210 UpdateRSOopClosure _cl;
1211 int _worker_i;
1212 public:
1213 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1214 _cl(g1->g1_rem_set(), worker_i),
1215 _worker_i(worker_i),
1216 _g1h(g1)
1217 { }
1218
1219 bool doHeapRegion(HeapRegion* r) {
1220 if (!r->continuesHumongous()) {
1221 _cl.set_from(r);
1222 r->oop_iterate(&_cl);
1223 }
1224 return false;
1225 }
1226 };
1227
1228 class ParRebuildRSTask: public AbstractGangTask {
1229 G1CollectedHeap* _g1;
1230 public:
1231 ParRebuildRSTask(G1CollectedHeap* g1)
1232 : AbstractGangTask("ParRebuildRSTask"),
1233 _g1(g1)
1234 { }
1235
1236 void work(uint worker_id) {
1237 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1238 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1239 _g1->workers()->active_workers(),
1240 HeapRegion::RebuildRSClaimValue);
1241 }
1242 };
1243
1244 class PostCompactionPrinterClosure: public HeapRegionClosure {
1245 private:
1246 G1HRPrinter* _hr_printer;
1247 public:
1248 bool doHeapRegion(HeapRegion* hr) {
1249 assert(!hr->is_young(), "not expecting to find young regions");
1250 // We only generate output for non-empty regions.
1251 if (!hr->is_empty()) {
1252 if (!hr->isHumongous()) {
1253 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1254 } else if (hr->startsHumongous()) {
1255 if (hr->region_num() == 1) {
1256 // single humongous region
1257 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1258 } else {
1259 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1260 }
1261 } else {
1262 assert(hr->continuesHumongous(), "only way to get here");
1263 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1264 }
1265 }
1266 return false;
1267 }
1268
1269 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1270 : _hr_printer(hr_printer) { }
1271 };
1272
1273 void G1CollectedHeap::print_hrs_post_compaction() {
1274 PostCompactionPrinterClosure cl(hr_printer());
1275 heap_region_iterate(&cl);
1276 }
1277
1278 bool G1CollectedHeap::do_collection(bool explicit_gc,
1279 bool clear_all_soft_refs,
1280 size_t word_size) {
1281 assert_at_safepoint(true /* should_be_vm_thread */);
1282
1283 if (GC_locker::check_active_before_gc()) {
1284 return false;
1285 }
1286
1287 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1288 gc_timer->register_gc_start();
1289
1290 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1291 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1292
1293 SvcGCMarker sgcm(SvcGCMarker::FULL);
1294 ResourceMark rm;
1295
1296 print_heap_before_gc();
1297 trace_heap_before_gc(gc_tracer);
1298
1299 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1300
1301 verify_region_sets_optional();
1302
1303 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1304 collector_policy()->should_clear_all_soft_refs();
1305
1306 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1307
1308 {
1309 IsGCActiveMark x;
1310
1311 // Timing
1312 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1313 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1314 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1315
1316 {
1317 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1318 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1319 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1320
1321 double start = os::elapsedTime();
1322 g1_policy()->record_full_collection_start();
1323
1324 // Note: When we have a more flexible GC logging framework that
1325 // allows us to add optional attributes to a GC log record we
1326 // could consider timing and reporting how long we wait in the
1327 // following two methods.
1328 wait_while_free_regions_coming();
1329 // If we start the compaction before the CM threads finish
1330 // scanning the root regions we might trip them over as we'll
1331 // be moving objects / updating references. So let's wait until
1332 // they are done. By telling them to abort, they should complete
1333 // early.
1334 _cm->root_regions()->abort();
1335 _cm->root_regions()->wait_until_scan_finished();
1336 append_secondary_free_list_if_not_empty_with_lock();
1337
1338 gc_prologue(true);
1339 increment_total_collections(true /* full gc */);
1340 increment_old_marking_cycles_started();
1341
1342 assert(used() == recalculate_used(), "Should be equal");
1343
1344 verify_before_gc();
1345
1346 pre_full_gc_dump(gc_timer);
1347
1348 COMPILER2_PRESENT(DerivedPointerTable::clear());
1349
1350 // Disable discovery and empty the discovered lists
1351 // for the CM ref processor.
1352 ref_processor_cm()->disable_discovery();
1353 ref_processor_cm()->abandon_partial_discovery();
1354 ref_processor_cm()->verify_no_references_recorded();
1355
1356 // Abandon current iterations of concurrent marking and concurrent
1357 // refinement, if any are in progress. We have to do this before
1358 // wait_until_scan_finished() below.
1359 concurrent_mark()->abort();
1360
1361 // Make sure we'll choose a new allocation region afterwards.
1362 release_mutator_alloc_region();
1363 abandon_gc_alloc_regions();
1364 g1_rem_set()->cleanupHRRS();
1365
1366 // We should call this after we retire any currently active alloc
1367 // regions so that all the ALLOC / RETIRE events are generated
1368 // before the start GC event.
1369 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1370
1371 // We may have added regions to the current incremental collection
1372 // set between the last GC or pause and now. We need to clear the
1373 // incremental collection set and then start rebuilding it afresh
1374 // after this full GC.
1375 abandon_collection_set(g1_policy()->inc_cset_head());
1376 g1_policy()->clear_incremental_cset();
1377 g1_policy()->stop_incremental_cset_building();
1378
1379 tear_down_region_sets(false /* free_list_only */);
1380 g1_policy()->set_gcs_are_young(true);
1381
1382 // See the comments in g1CollectedHeap.hpp and
1383 // G1CollectedHeap::ref_processing_init() about
1384 // how reference processing currently works in G1.
1385
1386 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1387 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1388
1389 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1390 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1391
1392 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1393 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1394
1395 // Do collection work
1396 {
1397 HandleMark hm; // Discard invalid handles created during gc
1398 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1399 }
1400
1401 assert(free_regions() == 0, "we should not have added any free regions");
1402 rebuild_region_sets(false /* free_list_only */);
1403
1404 // Enqueue any discovered reference objects that have
1405 // not been removed from the discovered lists.
1406 ref_processor_stw()->enqueue_discovered_references();
1407
1408 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1409
1410 MemoryService::track_memory_usage();
1411
1412 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1413 ref_processor_stw()->verify_no_references_recorded();
1414
1415 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1416 ClassLoaderDataGraph::purge();
1417 MetaspaceAux::verify_metrics();
1418
1419 // Note: since we've just done a full GC, concurrent
1420 // marking is no longer active. Therefore we need not
1421 // re-enable reference discovery for the CM ref processor.
1422 // That will be done at the start of the next marking cycle.
1423 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1424 ref_processor_cm()->verify_no_references_recorded();
1425
1426 reset_gc_time_stamp();
1427 // Since everything potentially moved, we will clear all remembered
1428 // sets, and clear all cards. Later we will rebuild remembered
1429 // sets. We will also reset the GC time stamps of the regions.
1430 clear_rsets_post_compaction();
1431 check_gc_time_stamps();
1432
1433 // Resize the heap if necessary.
1434 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1435
1436 if (_hr_printer.is_active()) {
1437 // We should do this after we potentially resize the heap so
1438 // that all the COMMIT / UNCOMMIT events are generated before
1439 // the end GC event.
1440
1441 print_hrs_post_compaction();
1442 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1443 }
1444
1445 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1446 if (hot_card_cache->use_cache()) {
1447 hot_card_cache->reset_card_counts();
1448 hot_card_cache->reset_hot_cache();
1449 }
1450
1451 // Rebuild remembered sets of all regions.
1452 if (G1CollectedHeap::use_parallel_gc_threads()) {
1453 uint n_workers =
1454 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1455 workers()->active_workers(),
1456 Threads::number_of_non_daemon_threads());
1457 assert(UseDynamicNumberOfGCThreads ||
1458 n_workers == workers()->total_workers(),
1459 "If not dynamic should be using all the workers");
1460 workers()->set_active_workers(n_workers);
1461 // Set parallel threads in the heap (_n_par_threads) only
1462 // before a parallel phase and always reset it to 0 after
1463 // the phase so that the number of parallel threads does
1464 // no get carried forward to a serial phase where there
1465 // may be code that is "possibly_parallel".
1466 set_par_threads(n_workers);
1467
1468 ParRebuildRSTask rebuild_rs_task(this);
1469 assert(check_heap_region_claim_values(
1470 HeapRegion::InitialClaimValue), "sanity check");
1471 assert(UseDynamicNumberOfGCThreads ||
1472 workers()->active_workers() == workers()->total_workers(),
1473 "Unless dynamic should use total workers");
1474 // Use the most recent number of active workers
1475 assert(workers()->active_workers() > 0,
1476 "Active workers not properly set");
1477 set_par_threads(workers()->active_workers());
1478 workers()->run_task(&rebuild_rs_task);
1479 set_par_threads(0);
1480 assert(check_heap_region_claim_values(
1481 HeapRegion::RebuildRSClaimValue), "sanity check");
1482 reset_heap_region_claim_values();
1483 } else {
1484 RebuildRSOutOfRegionClosure rebuild_rs(this);
1485 heap_region_iterate(&rebuild_rs);
1486 }
1487
1488 // Rebuild the strong code root lists for each region
1489 rebuild_strong_code_roots();
1490
1491 if (true) { // FIXME
1492 MetaspaceGC::compute_new_size();
1493 }
1494
1495 #ifdef TRACESPINNING
1496 ParallelTaskTerminator::print_termination_counts();
1497 #endif
1498
1499 // Discard all rset updates
1500 JavaThread::dirty_card_queue_set().abandon_logs();
1501 assert(!G1DeferredRSUpdate
1502 || (G1DeferredRSUpdate &&
1503 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1504
1505 _young_list->reset_sampled_info();
1506 // At this point there should be no regions in the
1507 // entire heap tagged as young.
1508 assert(check_young_list_empty(true /* check_heap */),
1509 "young list should be empty at this point");
1510
1511 // Update the number of full collections that have been completed.
1512 increment_old_marking_cycles_completed(false /* concurrent */);
1513
1514 _hrs.verify_optional();
1515 verify_region_sets_optional();
1516
1517 verify_after_gc();
1518
1519 // Start a new incremental collection set for the next pause
1520 assert(g1_policy()->collection_set() == NULL, "must be");
1521 g1_policy()->start_incremental_cset_building();
1522
1523 // Clear the _cset_fast_test bitmap in anticipation of adding
1524 // regions to the incremental collection set for the next
1525 // evacuation pause.
1526 clear_cset_fast_test();
1527
1528 init_mutator_alloc_region();
1529
1530 double end = os::elapsedTime();
1531 g1_policy()->record_full_collection_end();
1532
1533 if (G1Log::fine()) {
1534 g1_policy()->print_heap_transition();
1535 }
1536
1537 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1538 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1539 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1540 // before any GC notifications are raised.
1541 g1mm()->update_sizes();
1542
1543 gc_epilogue(true);
1544 }
1545
1546 if (G1Log::finer()) {
1547 g1_policy()->print_detailed_heap_transition(true /* full */);
1548 }
1549
1550 print_heap_after_gc();
1551 trace_heap_after_gc(gc_tracer);
1552
1553 post_full_gc_dump(gc_timer);
1554
1555 gc_timer->register_gc_end();
1556 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1557 }
1558
1559 return true;
1560 }
1561
1562 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1563 // do_collection() will return whether it succeeded in performing
1564 // the GC. Currently, there is no facility on the
1565 // do_full_collection() API to notify the caller than the collection
1566 // did not succeed (e.g., because it was locked out by the GC
1567 // locker). So, right now, we'll ignore the return value.
1568 bool dummy = do_collection(true, /* explicit_gc */
1569 clear_all_soft_refs,
1570 0 /* word_size */);
1571 }
1572
1573 // This code is mostly copied from TenuredGeneration.
1574 void
1575 G1CollectedHeap::
1576 resize_if_necessary_after_full_collection(size_t word_size) {
1577 // Include the current allocation, if any, and bytes that will be
1578 // pre-allocated to support collections, as "used".
1579 const size_t used_after_gc = used();
1580 const size_t capacity_after_gc = capacity();
1581 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1582
1583 // This is enforced in arguments.cpp.
1584 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1585 "otherwise the code below doesn't make sense");
1586
1587 // We don't have floating point command-line arguments
1588 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1589 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1590 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1591 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1592
1593 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1594 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1595
1596 // We have to be careful here as these two calculations can overflow
1597 // 32-bit size_t's.
1598 double used_after_gc_d = (double) used_after_gc;
1599 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1600 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1601
1602 // Let's make sure that they are both under the max heap size, which
1603 // by default will make them fit into a size_t.
1604 double desired_capacity_upper_bound = (double) max_heap_size;
1605 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1606 desired_capacity_upper_bound);
1607 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1608 desired_capacity_upper_bound);
1609
1610 // We can now safely turn them into size_t's.
1611 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1612 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1613
1614 // This assert only makes sense here, before we adjust them
1615 // with respect to the min and max heap size.
1616 assert(minimum_desired_capacity <= maximum_desired_capacity,
1617 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1618 "maximum_desired_capacity = "SIZE_FORMAT,
1619 minimum_desired_capacity, maximum_desired_capacity));
1620
1621 // Should not be greater than the heap max size. No need to adjust
1622 // it with respect to the heap min size as it's a lower bound (i.e.,
1623 // we'll try to make the capacity larger than it, not smaller).
1624 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1625 // Should not be less than the heap min size. No need to adjust it
1626 // with respect to the heap max size as it's an upper bound (i.e.,
1627 // we'll try to make the capacity smaller than it, not greater).
1628 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1629
1630 if (capacity_after_gc < minimum_desired_capacity) {
1631 // Don't expand unless it's significant
1632 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1633 ergo_verbose4(ErgoHeapSizing,
1634 "attempt heap expansion",
1635 ergo_format_reason("capacity lower than "
1636 "min desired capacity after Full GC")
1637 ergo_format_byte("capacity")
1638 ergo_format_byte("occupancy")
1639 ergo_format_byte_perc("min desired capacity"),
1640 capacity_after_gc, used_after_gc,
1641 minimum_desired_capacity, (double) MinHeapFreeRatio);
1642 expand(expand_bytes);
1643
1644 // No expansion, now see if we want to shrink
1645 } else if (capacity_after_gc > maximum_desired_capacity) {
1646 // Capacity too large, compute shrinking size
1647 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1648 ergo_verbose4(ErgoHeapSizing,
1649 "attempt heap shrinking",
1650 ergo_format_reason("capacity higher than "
1651 "max desired capacity after Full GC")
1652 ergo_format_byte("capacity")
1653 ergo_format_byte("occupancy")
1654 ergo_format_byte_perc("max desired capacity"),
1655 capacity_after_gc, used_after_gc,
1656 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1657 shrink(shrink_bytes);
1658 }
1659 }
1660
1661
1662 HeapWord*
1663 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1664 bool* succeeded) {
1665 assert_at_safepoint(true /* should_be_vm_thread */);
1666
1667 *succeeded = true;
1668 // Let's attempt the allocation first.
1669 HeapWord* result =
1670 attempt_allocation_at_safepoint(word_size,
1671 false /* expect_null_mutator_alloc_region */);
1672 if (result != NULL) {
1673 assert(*succeeded, "sanity");
1674 return result;
1675 }
1676
1677 // In a G1 heap, we're supposed to keep allocation from failing by
1678 // incremental pauses. Therefore, at least for now, we'll favor
1679 // expansion over collection. (This might change in the future if we can
1680 // do something smarter than full collection to satisfy a failed alloc.)
1681 result = expand_and_allocate(word_size);
1682 if (result != NULL) {
1683 assert(*succeeded, "sanity");
1684 return result;
1685 }
1686
1687 // Expansion didn't work, we'll try to do a Full GC.
1688 bool gc_succeeded = do_collection(false, /* explicit_gc */
1689 false, /* clear_all_soft_refs */
1690 word_size);
1691 if (!gc_succeeded) {
1692 *succeeded = false;
1693 return NULL;
1694 }
1695
1696 // Retry the allocation
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 // Then, try a Full GC that will collect all soft references.
1705 gc_succeeded = do_collection(false, /* explicit_gc */
1706 true, /* clear_all_soft_refs */
1707 word_size);
1708 if (!gc_succeeded) {
1709 *succeeded = false;
1710 return NULL;
1711 }
1712
1713 // Retry the allocation once more
1714 result = attempt_allocation_at_safepoint(word_size,
1715 true /* expect_null_mutator_alloc_region */);
1716 if (result != NULL) {
1717 assert(*succeeded, "sanity");
1718 return result;
1719 }
1720
1721 assert(!collector_policy()->should_clear_all_soft_refs(),
1722 "Flag should have been handled and cleared prior to this point");
1723
1724 // What else? We might try synchronous finalization later. If the total
1725 // space available is large enough for the allocation, then a more
1726 // complete compaction phase than we've tried so far might be
1727 // appropriate.
1728 assert(*succeeded, "sanity");
1729 return NULL;
1730 }
1731
1732 // Attempting to expand the heap sufficiently
1733 // to support an allocation of the given "word_size". If
1734 // successful, perform the allocation and return the address of the
1735 // allocated block, or else "NULL".
1736
1737 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1738 assert_at_safepoint(true /* should_be_vm_thread */);
1739
1740 verify_region_sets_optional();
1741
1742 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1743 ergo_verbose1(ErgoHeapSizing,
1744 "attempt heap expansion",
1745 ergo_format_reason("allocation request failed")
1746 ergo_format_byte("allocation request"),
1747 word_size * HeapWordSize);
1748 if (expand(expand_bytes)) {
1749 _hrs.verify_optional();
1750 verify_region_sets_optional();
1751 return attempt_allocation_at_safepoint(word_size,
1752 false /* expect_null_mutator_alloc_region */);
1753 }
1754 return NULL;
1755 }
1756
1757 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1758 HeapWord* new_end) {
1759 assert(old_end != new_end, "don't call this otherwise");
1760 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1761
1762 // Update the committed mem region.
1763 _g1_committed.set_end(new_end);
1764 // Tell the card table about the update.
1765 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1766 // Tell the BOT about the update.
1767 _bot_shared->resize(_g1_committed.word_size());
1768 // Tell the hot card cache about the update
1769 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1770 }
1771
1772 bool G1CollectedHeap::expand(size_t expand_bytes) {
1773 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1774 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1775 HeapRegion::GrainBytes);
1776 ergo_verbose2(ErgoHeapSizing,
1777 "expand the heap",
1778 ergo_format_byte("requested expansion amount")
1779 ergo_format_byte("attempted expansion amount"),
1780 expand_bytes, aligned_expand_bytes);
1781
1782 if (_g1_storage.uncommitted_size() == 0) {
1783 ergo_verbose0(ErgoHeapSizing,
1784 "did not expand the heap",
1785 ergo_format_reason("heap already fully expanded"));
1786 return false;
1787 }
1788
1789 // First commit the memory.
1790 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1791 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1792 if (successful) {
1793 // Then propagate this update to the necessary data structures.
1794 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1795 update_committed_space(old_end, new_end);
1796
1797 FreeRegionList expansion_list("Local Expansion List");
1798 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1799 assert(mr.start() == old_end, "post-condition");
1800 // mr might be a smaller region than what was requested if
1801 // expand_by() was unable to allocate the HeapRegion instances
1802 assert(mr.end() <= new_end, "post-condition");
1803
1804 size_t actual_expand_bytes = mr.byte_size();
1805 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1806 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1807 "post-condition");
1808 if (actual_expand_bytes < aligned_expand_bytes) {
1809 // We could not expand _hrs to the desired size. In this case we
1810 // need to shrink the committed space accordingly.
1811 assert(mr.end() < new_end, "invariant");
1812
1813 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1814 // First uncommit the memory.
1815 _g1_storage.shrink_by(diff_bytes);
1816 // Then propagate this update to the necessary data structures.
1817 update_committed_space(new_end, mr.end());
1818 }
1819 _free_list.add_as_tail(&expansion_list);
1820
1821 if (_hr_printer.is_active()) {
1822 HeapWord* curr = mr.start();
1823 while (curr < mr.end()) {
1824 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1825 _hr_printer.commit(curr, curr_end);
1826 curr = curr_end;
1827 }
1828 assert(curr == mr.end(), "post-condition");
1829 }
1830 g1_policy()->record_new_heap_size(n_regions());
1831 } else {
1832 ergo_verbose0(ErgoHeapSizing,
1833 "did not expand the heap",
1834 ergo_format_reason("heap expansion operation failed"));
1835 // The expansion of the virtual storage space was unsuccessful.
1836 // Let's see if it was because we ran out of swap.
1837 if (G1ExitOnExpansionFailure &&
1838 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1839 // We had head room...
1840 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1841 }
1842 }
1843 return successful;
1844 }
1845
1846 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1847 size_t aligned_shrink_bytes =
1848 ReservedSpace::page_align_size_down(shrink_bytes);
1849 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1850 HeapRegion::GrainBytes);
1851 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1852
1853 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1854 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1855 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1856
1857 ergo_verbose3(ErgoHeapSizing,
1858 "shrink the heap",
1859 ergo_format_byte("requested shrinking amount")
1860 ergo_format_byte("aligned shrinking amount")
1861 ergo_format_byte("attempted shrinking amount"),
1862 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1863 if (num_regions_removed > 0) {
1864 _g1_storage.shrink_by(shrunk_bytes);
1865 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1866
1867 if (_hr_printer.is_active()) {
1868 HeapWord* curr = old_end;
1869 while (curr > new_end) {
1870 HeapWord* curr_end = curr;
1871 curr -= HeapRegion::GrainWords;
1872 _hr_printer.uncommit(curr, curr_end);
1873 }
1874 }
1875
1876 _expansion_regions += num_regions_removed;
1877 update_committed_space(old_end, new_end);
1878 HeapRegionRemSet::shrink_heap(n_regions());
1879 g1_policy()->record_new_heap_size(n_regions());
1880 } else {
1881 ergo_verbose0(ErgoHeapSizing,
1882 "did not shrink the heap",
1883 ergo_format_reason("heap shrinking operation failed"));
1884 }
1885 }
1886
1887 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1888 verify_region_sets_optional();
1889
1890 // We should only reach here at the end of a Full GC which means we
1891 // should not not be holding to any GC alloc regions. The method
1892 // below will make sure of that and do any remaining clean up.
1893 abandon_gc_alloc_regions();
1894
1895 // Instead of tearing down / rebuilding the free lists here, we
1896 // could instead use the remove_all_pending() method on free_list to
1897 // remove only the ones that we need to remove.
1898 tear_down_region_sets(true /* free_list_only */);
1899 shrink_helper(shrink_bytes);
1900 rebuild_region_sets(true /* free_list_only */);
1901
1902 _hrs.verify_optional();
1903 verify_region_sets_optional();
1904 }
1905
1906 // Public methods.
1907
1908 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1909 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1910 #endif // _MSC_VER
1911
1912
1913 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1914 SharedHeap(policy_),
1915 _g1_policy(policy_),
1916 _dirty_card_queue_set(false),
1917 _into_cset_dirty_card_queue_set(false),
1918 _is_alive_closure_cm(this),
1919 _is_alive_closure_stw(this),
1920 _ref_processor_cm(NULL),
1921 _ref_processor_stw(NULL),
1922 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1923 _bot_shared(NULL),
1924 _evac_failure_scan_stack(NULL),
1925 _mark_in_progress(false),
1926 _cg1r(NULL), _summary_bytes_used(0),
1927 _g1mm(NULL),
1928 _refine_cte_cl(NULL),
1929 _full_collection(false),
1930 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1931 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1932 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1933 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1934 _free_regions_coming(false),
1935 _young_list(new YoungList(this)),
1936 _gc_time_stamp(0),
1937 _retained_old_gc_alloc_region(NULL),
1938 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1939 _old_plab_stats(OldPLABSize, PLABWeight),
1940 _expand_heap_after_alloc_failure(true),
1941 _surviving_young_words(NULL),
1942 _old_marking_cycles_started(0),
1943 _old_marking_cycles_completed(0),
1944 _concurrent_cycle_started(false),
1945 _in_cset_fast_test(NULL),
1946 _in_cset_fast_test_base(NULL),
1947 _dirty_cards_region_list(NULL),
1948 _worker_cset_start_region(NULL),
1949 _worker_cset_start_region_time_stamp(NULL),
1950 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1951 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1952 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1953 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1954
1955 _g1h = this;
1956 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1957 vm_exit_during_initialization("Failed necessary allocation.");
1958 }
1959
1960 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1961
1962 int n_queues = MAX2((int)ParallelGCThreads, 1);
1963 _task_queues = new RefToScanQueueSet(n_queues);
1964
1965 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1966 assert(n_rem_sets > 0, "Invariant.");
1967
1968 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1969 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1970 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1971
1972 for (int i = 0; i < n_queues; i++) {
1973 RefToScanQueue* q = new RefToScanQueue();
1974 q->initialize();
1975 _task_queues->register_queue(i, q);
1976 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1977 }
1978 clear_cset_start_regions();
1979
1980 // Initialize the G1EvacuationFailureALot counters and flags.
1981 NOT_PRODUCT(reset_evacuation_should_fail();)
1982
1983 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1984 }
1985
1986 jint G1CollectedHeap::initialize() {
1987 CollectedHeap::pre_initialize();
1988 os::enable_vtime();
1989
1990 G1Log::init();
1991
1992 // Necessary to satisfy locking discipline assertions.
1993
1994 MutexLocker x(Heap_lock);
1995
1996 // We have to initialize the printer before committing the heap, as
1997 // it will be used then.
1998 _hr_printer.set_active(G1PrintHeapRegions);
1999
2000 // While there are no constraints in the GC code that HeapWordSize
2001 // be any particular value, there are multiple other areas in the
2002 // system which believe this to be true (e.g. oop->object_size in some
2003 // cases incorrectly returns the size in wordSize units rather than
2004 // HeapWordSize).
2005 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2006
2007 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2008 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2009 size_t heap_alignment = collector_policy()->heap_alignment();
2010
2011 // Ensure that the sizes are properly aligned.
2012 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2013 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2014 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2015
2016 _cg1r = new ConcurrentG1Refine(this);
2017
2018 // Reserve the maximum.
2019
2020 // When compressed oops are enabled, the preferred heap base
2021 // is calculated by subtracting the requested size from the
2022 // 32Gb boundary and using the result as the base address for
2023 // heap reservation. If the requested size is not aligned to
2024 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2025 // into the ReservedHeapSpace constructor) then the actual
2026 // base of the reserved heap may end up differing from the
2027 // address that was requested (i.e. the preferred heap base).
2028 // If this happens then we could end up using a non-optimal
2029 // compressed oops mode.
2030
2031 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2032 heap_alignment);
2033
2034 // It is important to do this in a way such that concurrent readers can't
2035 // temporarily think something is in the heap. (I've actually seen this
2036 // happen in asserts: DLD.)
2037 _reserved.set_word_size(0);
2038 _reserved.set_start((HeapWord*)heap_rs.base());
2039 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2040
2041 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2042
2043 // Create the gen rem set (and barrier set) for the entire reserved region.
2044 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2045 set_barrier_set(rem_set()->bs());
2046 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2047 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2048 return JNI_ENOMEM;
2049 }
2050
2051 // Also create a G1 rem set.
2052 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2053
2054 // Carve out the G1 part of the heap.
2055
2056 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2057 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2058 g1_rs.size()/HeapWordSize);
2059
2060 _g1_storage.initialize(g1_rs, 0);
2061 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2062 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2063 (HeapWord*) _g1_reserved.end());
2064 assert(_hrs.max_length() == _expansion_regions,
2065 err_msg("max length: %u expansion regions: %u",
2066 _hrs.max_length(), _expansion_regions));
2067
2068 // Do later initialization work for concurrent refinement.
2069 _cg1r->init();
2070
2071 // 6843694 - ensure that the maximum region index can fit
2072 // in the remembered set structures.
2073 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2074 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2075
2076 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2077 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2078 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2079 "too many cards per region");
2080
2081 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2082
2083 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2084 heap_word_size(init_byte_size));
2085
2086 _g1h = this;
2087
2088 _in_cset_fast_test_length = max_regions();
2089 _in_cset_fast_test_base =
2090 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2091
2092 // We're biasing _in_cset_fast_test to avoid subtracting the
2093 // beginning of the heap every time we want to index; basically
2094 // it's the same with what we do with the card table.
2095 _in_cset_fast_test = _in_cset_fast_test_base -
2096 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2097
2098 // Clear the _cset_fast_test bitmap in anticipation of adding
2099 // regions to the incremental collection set for the first
2100 // evacuation pause.
2101 clear_cset_fast_test();
2102
2103 // Create the ConcurrentMark data structure and thread.
2104 // (Must do this late, so that "max_regions" is defined.)
2105 _cm = new ConcurrentMark(this, heap_rs);
2106 if (_cm == NULL || !_cm->completed_initialization()) {
2107 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2108 return JNI_ENOMEM;
2109 }
2110 _cmThread = _cm->cmThread();
2111
2112 // Initialize the from_card cache structure of HeapRegionRemSet.
2113 HeapRegionRemSet::init_heap(max_regions());
2114
2115 // Now expand into the initial heap size.
2116 if (!expand(init_byte_size)) {
2117 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2118 return JNI_ENOMEM;
2119 }
2120
2121 // Perform any initialization actions delegated to the policy.
2122 g1_policy()->init();
2123
2124 _refine_cte_cl =
2125 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2126 g1_rem_set(),
2127 concurrent_g1_refine());
2128 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2129
2130 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2131 SATB_Q_FL_lock,
2132 G1SATBProcessCompletedThreshold,
2133 Shared_SATB_Q_lock);
2134
2135 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2136 DirtyCardQ_FL_lock,
2137 concurrent_g1_refine()->yellow_zone(),
2138 concurrent_g1_refine()->red_zone(),
2139 Shared_DirtyCardQ_lock);
2140
2141 if (G1DeferredRSUpdate) {
2142 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2143 DirtyCardQ_FL_lock,
2144 -1, // never trigger processing
2145 -1, // no limit on length
2146 Shared_DirtyCardQ_lock,
2147 &JavaThread::dirty_card_queue_set());
2148 }
2149
2150 // Initialize the card queue set used to hold cards containing
2151 // references into the collection set.
2152 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2153 DirtyCardQ_FL_lock,
2154 -1, // never trigger processing
2155 -1, // no limit on length
2156 Shared_DirtyCardQ_lock,
2157 &JavaThread::dirty_card_queue_set());
2158
2159 // In case we're keeping closure specialization stats, initialize those
2160 // counts and that mechanism.
2161 SpecializationStats::clear();
2162
2163 // Here we allocate the dummy full region that is required by the
2164 // G1AllocRegion class. If we don't pass an address in the reserved
2165 // space here, lots of asserts fire.
2166
2167 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2168 _g1_reserved.start());
2169 // We'll re-use the same region whether the alloc region will
2170 // require BOT updates or not and, if it doesn't, then a non-young
2171 // region will complain that it cannot support allocations without
2172 // BOT updates. So we'll tag the dummy region as young to avoid that.
2173 dummy_region->set_young();
2174 // Make sure it's full.
2175 dummy_region->set_top(dummy_region->end());
2176 G1AllocRegion::setup(this, dummy_region);
2177
2178 init_mutator_alloc_region();
2179
2180 // Do create of the monitoring and management support so that
2181 // values in the heap have been properly initialized.
2182 _g1mm = new G1MonitoringSupport(this);
2183
2184 return JNI_OK;
2185 }
2186
2187 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2188 return HeapRegion::max_region_size();
2189 }
2190
2191 void G1CollectedHeap::ref_processing_init() {
2192 // Reference processing in G1 currently works as follows:
2193 //
2194 // * There are two reference processor instances. One is
2195 // used to record and process discovered references
2196 // during concurrent marking; the other is used to
2197 // record and process references during STW pauses
2198 // (both full and incremental).
2199 // * Both ref processors need to 'span' the entire heap as
2200 // the regions in the collection set may be dotted around.
2201 //
2202 // * For the concurrent marking ref processor:
2203 // * Reference discovery is enabled at initial marking.
2204 // * Reference discovery is disabled and the discovered
2205 // references processed etc during remarking.
2206 // * Reference discovery is MT (see below).
2207 // * Reference discovery requires a barrier (see below).
2208 // * Reference processing may or may not be MT
2209 // (depending on the value of ParallelRefProcEnabled
2210 // and ParallelGCThreads).
2211 // * A full GC disables reference discovery by the CM
2212 // ref processor and abandons any entries on it's
2213 // discovered lists.
2214 //
2215 // * For the STW processor:
2216 // * Non MT discovery is enabled at the start of a full GC.
2217 // * Processing and enqueueing during a full GC is non-MT.
2218 // * During a full GC, references are processed after marking.
2219 //
2220 // * Discovery (may or may not be MT) is enabled at the start
2221 // of an incremental evacuation pause.
2222 // * References are processed near the end of a STW evacuation pause.
2223 // * For both types of GC:
2224 // * Discovery is atomic - i.e. not concurrent.
2225 // * Reference discovery will not need a barrier.
2226
2227 SharedHeap::ref_processing_init();
2228 MemRegion mr = reserved_region();
2229
2230 // Concurrent Mark ref processor
2231 _ref_processor_cm =
2232 new ReferenceProcessor(mr, // span
2233 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2234 // mt processing
2235 (int) ParallelGCThreads,
2236 // degree of mt processing
2237 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2238 // mt discovery
2239 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2240 // degree of mt discovery
2241 false,
2242 // Reference discovery is not atomic
2243 &_is_alive_closure_cm,
2244 // is alive closure
2245 // (for efficiency/performance)
2246 true);
2247 // Setting next fields of discovered
2248 // lists requires a barrier.
2249
2250 // STW ref processor
2251 _ref_processor_stw =
2252 new ReferenceProcessor(mr, // span
2253 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2254 // mt processing
2255 MAX2((int)ParallelGCThreads, 1),
2256 // degree of mt processing
2257 (ParallelGCThreads > 1),
2258 // mt discovery
2259 MAX2((int)ParallelGCThreads, 1),
2260 // degree of mt discovery
2261 true,
2262 // Reference discovery is atomic
2263 &_is_alive_closure_stw,
2264 // is alive closure
2265 // (for efficiency/performance)
2266 false);
2267 // Setting next fields of discovered
2268 // lists does not require a barrier.
2269 }
2270
2271 size_t G1CollectedHeap::capacity() const {
2272 return _g1_committed.byte_size();
2273 }
2274
2275 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2276 assert(!hr->continuesHumongous(), "pre-condition");
2277 hr->reset_gc_time_stamp();
2278 if (hr->startsHumongous()) {
2279 uint first_index = hr->hrs_index() + 1;
2280 uint last_index = hr->last_hc_index();
2281 for (uint i = first_index; i < last_index; i += 1) {
2282 HeapRegion* chr = region_at(i);
2283 assert(chr->continuesHumongous(), "sanity");
2284 chr->reset_gc_time_stamp();
2285 }
2286 }
2287 }
2288
2289 #ifndef PRODUCT
2290 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2291 private:
2292 unsigned _gc_time_stamp;
2293 bool _failures;
2294
2295 public:
2296 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2297 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2298
2299 virtual bool doHeapRegion(HeapRegion* hr) {
2300 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2301 if (_gc_time_stamp != region_gc_time_stamp) {
2302 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2303 "expected %d", HR_FORMAT_PARAMS(hr),
2304 region_gc_time_stamp, _gc_time_stamp);
2305 _failures = true;
2306 }
2307 return false;
2308 }
2309
2310 bool failures() { return _failures; }
2311 };
2312
2313 void G1CollectedHeap::check_gc_time_stamps() {
2314 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2315 heap_region_iterate(&cl);
2316 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2317 }
2318 #endif // PRODUCT
2319
2320 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2321 DirtyCardQueue* into_cset_dcq,
2322 bool concurrent,
2323 int worker_i) {
2324 // Clean cards in the hot card cache
2325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2326 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2327
2328 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2329 int n_completed_buffers = 0;
2330 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2331 n_completed_buffers++;
2332 }
2333 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2334 dcqs.clear_n_completed_buffers();
2335 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2336 }
2337
2338
2339 // Computes the sum of the storage used by the various regions.
2340
2341 size_t G1CollectedHeap::used() const {
2342 assert(Heap_lock->owner() != NULL,
2343 "Should be owned on this thread's behalf.");
2344 size_t result = _summary_bytes_used;
2345 // Read only once in case it is set to NULL concurrently
2346 HeapRegion* hr = _mutator_alloc_region.get();
2347 if (hr != NULL)
2348 result += hr->used();
2349 return result;
2350 }
2351
2352 size_t G1CollectedHeap::used_unlocked() const {
2353 size_t result = _summary_bytes_used;
2354 return result;
2355 }
2356
2357 class SumUsedClosure: public HeapRegionClosure {
2358 size_t _used;
2359 public:
2360 SumUsedClosure() : _used(0) {}
2361 bool doHeapRegion(HeapRegion* r) {
2362 if (!r->continuesHumongous()) {
2363 _used += r->used();
2364 }
2365 return false;
2366 }
2367 size_t result() { return _used; }
2368 };
2369
2370 size_t G1CollectedHeap::recalculate_used() const {
2371 SumUsedClosure blk;
2372 heap_region_iterate(&blk);
2373 return blk.result();
2374 }
2375
2376 size_t G1CollectedHeap::unsafe_max_alloc() {
2377 if (free_regions() > 0) return HeapRegion::GrainBytes;
2378 // otherwise, is there space in the current allocation region?
2379
2380 // We need to store the current allocation region in a local variable
2381 // here. The problem is that this method doesn't take any locks and
2382 // there may be other threads which overwrite the current allocation
2383 // region field. attempt_allocation(), for example, sets it to NULL
2384 // and this can happen *after* the NULL check here but before the call
2385 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2386 // to be a problem in the optimized build, since the two loads of the
2387 // current allocation region field are optimized away.
2388 HeapRegion* hr = _mutator_alloc_region.get();
2389 if (hr == NULL) {
2390 return 0;
2391 }
2392 return hr->free();
2393 }
2394
2395 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2396 switch (cause) {
2397 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2398 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2399 case GCCause::_g1_humongous_allocation: return true;
2400 default: return false;
2401 }
2402 }
2403
2404 #ifndef PRODUCT
2405 void G1CollectedHeap::allocate_dummy_regions() {
2406 // Let's fill up most of the region
2407 size_t word_size = HeapRegion::GrainWords - 1024;
2408 // And as a result the region we'll allocate will be humongous.
2409 guarantee(isHumongous(word_size), "sanity");
2410
2411 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2412 // Let's use the existing mechanism for the allocation
2413 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2414 if (dummy_obj != NULL) {
2415 MemRegion mr(dummy_obj, word_size);
2416 CollectedHeap::fill_with_object(mr);
2417 } else {
2418 // If we can't allocate once, we probably cannot allocate
2419 // again. Let's get out of the loop.
2420 break;
2421 }
2422 }
2423 }
2424 #endif // !PRODUCT
2425
2426 void G1CollectedHeap::increment_old_marking_cycles_started() {
2427 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2428 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2429 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2430 _old_marking_cycles_started, _old_marking_cycles_completed));
2431
2432 _old_marking_cycles_started++;
2433 }
2434
2435 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2436 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2437
2438 // We assume that if concurrent == true, then the caller is a
2439 // concurrent thread that was joined the Suspendible Thread
2440 // Set. If there's ever a cheap way to check this, we should add an
2441 // assert here.
2442
2443 // Given that this method is called at the end of a Full GC or of a
2444 // concurrent cycle, and those can be nested (i.e., a Full GC can
2445 // interrupt a concurrent cycle), the number of full collections
2446 // completed should be either one (in the case where there was no
2447 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2448 // behind the number of full collections started.
2449
2450 // This is the case for the inner caller, i.e. a Full GC.
2451 assert(concurrent ||
2452 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2453 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2454 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2455 "is inconsistent with _old_marking_cycles_completed = %u",
2456 _old_marking_cycles_started, _old_marking_cycles_completed));
2457
2458 // This is the case for the outer caller, i.e. the concurrent cycle.
2459 assert(!concurrent ||
2460 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2461 err_msg("for outer caller (concurrent cycle): "
2462 "_old_marking_cycles_started = %u "
2463 "is inconsistent with _old_marking_cycles_completed = %u",
2464 _old_marking_cycles_started, _old_marking_cycles_completed));
2465
2466 _old_marking_cycles_completed += 1;
2467
2468 // We need to clear the "in_progress" flag in the CM thread before
2469 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2470 // is set) so that if a waiter requests another System.gc() it doesn't
2471 // incorrectly see that a marking cycle is still in progress.
2472 if (concurrent) {
2473 _cmThread->clear_in_progress();
2474 }
2475
2476 // This notify_all() will ensure that a thread that called
2477 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2478 // and it's waiting for a full GC to finish will be woken up. It is
2479 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2480 FullGCCount_lock->notify_all();
2481 }
2482
2483 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2484 _concurrent_cycle_started = true;
2485 _gc_timer_cm->register_gc_start(start_time);
2486
2487 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2488 trace_heap_before_gc(_gc_tracer_cm);
2489 }
2490
2491 void G1CollectedHeap::register_concurrent_cycle_end() {
2492 if (_concurrent_cycle_started) {
2493 if (_cm->has_aborted()) {
2494 _gc_tracer_cm->report_concurrent_mode_failure();
2495 }
2496
2497 _gc_timer_cm->register_gc_end();
2498 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2499
2500 _concurrent_cycle_started = false;
2501 }
2502 }
2503
2504 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2505 if (_concurrent_cycle_started) {
2506 trace_heap_after_gc(_gc_tracer_cm);
2507 }
2508 }
2509
2510 G1YCType G1CollectedHeap::yc_type() {
2511 bool is_young = g1_policy()->gcs_are_young();
2512 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2513 bool is_during_mark = mark_in_progress();
2514
2515 if (is_initial_mark) {
2516 return InitialMark;
2517 } else if (is_during_mark) {
2518 return DuringMark;
2519 } else if (is_young) {
2520 return Normal;
2521 } else {
2522 return Mixed;
2523 }
2524 }
2525
2526 void G1CollectedHeap::collect(GCCause::Cause cause) {
2527 assert_heap_not_locked();
2528
2529 unsigned int gc_count_before;
2530 unsigned int old_marking_count_before;
2531 bool retry_gc;
2532
2533 do {
2534 retry_gc = false;
2535
2536 {
2537 MutexLocker ml(Heap_lock);
2538
2539 // Read the GC count while holding the Heap_lock
2540 gc_count_before = total_collections();
2541 old_marking_count_before = _old_marking_cycles_started;
2542 }
2543
2544 if (should_do_concurrent_full_gc(cause)) {
2545 // Schedule an initial-mark evacuation pause that will start a
2546 // concurrent cycle. We're setting word_size to 0 which means that
2547 // we are not requesting a post-GC allocation.
2548 VM_G1IncCollectionPause op(gc_count_before,
2549 0, /* word_size */
2550 true, /* should_initiate_conc_mark */
2551 g1_policy()->max_pause_time_ms(),
2552 cause);
2553
2554 VMThread::execute(&op);
2555 if (!op.pause_succeeded()) {
2556 if (old_marking_count_before == _old_marking_cycles_started) {
2557 retry_gc = op.should_retry_gc();
2558 } else {
2559 // A Full GC happened while we were trying to schedule the
2560 // initial-mark GC. No point in starting a new cycle given
2561 // that the whole heap was collected anyway.
2562 }
2563
2564 if (retry_gc) {
2565 if (GC_locker::is_active_and_needs_gc()) {
2566 GC_locker::stall_until_clear();
2567 }
2568 }
2569 }
2570 } else {
2571 if (cause == GCCause::_gc_locker
2572 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2573
2574 // Schedule a standard evacuation pause. We're setting word_size
2575 // to 0 which means that we are not requesting a post-GC allocation.
2576 VM_G1IncCollectionPause op(gc_count_before,
2577 0, /* word_size */
2578 false, /* should_initiate_conc_mark */
2579 g1_policy()->max_pause_time_ms(),
2580 cause);
2581 VMThread::execute(&op);
2582 } else {
2583 // Schedule a Full GC.
2584 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2585 VMThread::execute(&op);
2586 }
2587 }
2588 } while (retry_gc);
2589 }
2590
2591 bool G1CollectedHeap::is_in(const void* p) const {
2592 if (_g1_committed.contains(p)) {
2593 // Given that we know that p is in the committed space,
2594 // heap_region_containing_raw() should successfully
2595 // return the containing region.
2596 HeapRegion* hr = heap_region_containing_raw(p);
2597 return hr->is_in(p);
2598 } else {
2599 return false;
2600 }
2601 }
2602
2603 // Iteration functions.
2604
2605 // Iterates an OopClosure over all ref-containing fields of objects
2606 // within a HeapRegion.
2607
2608 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2609 MemRegion _mr;
2610 ExtendedOopClosure* _cl;
2611 public:
2612 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2613 : _mr(mr), _cl(cl) {}
2614 bool doHeapRegion(HeapRegion* r) {
2615 if (!r->continuesHumongous()) {
2616 r->oop_iterate(_cl);
2617 }
2618 return false;
2619 }
2620 };
2621
2622 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2623 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2624 heap_region_iterate(&blk);
2625 }
2626
2627 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2628 IterateOopClosureRegionClosure blk(mr, cl);
2629 heap_region_iterate(&blk);
2630 }
2631
2632 // Iterates an ObjectClosure over all objects within a HeapRegion.
2633
2634 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2635 ObjectClosure* _cl;
2636 public:
2637 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2638 bool doHeapRegion(HeapRegion* r) {
2639 if (! r->continuesHumongous()) {
2640 r->object_iterate(_cl);
2641 }
2642 return false;
2643 }
2644 };
2645
2646 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2647 IterateObjectClosureRegionClosure blk(cl);
2648 heap_region_iterate(&blk);
2649 }
2650
2651 // Calls a SpaceClosure on a HeapRegion.
2652
2653 class SpaceClosureRegionClosure: public HeapRegionClosure {
2654 SpaceClosure* _cl;
2655 public:
2656 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2657 bool doHeapRegion(HeapRegion* r) {
2658 _cl->do_space(r);
2659 return false;
2660 }
2661 };
2662
2663 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2664 SpaceClosureRegionClosure blk(cl);
2665 heap_region_iterate(&blk);
2666 }
2667
2668 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2669 _hrs.iterate(cl);
2670 }
2671
2672 void
2673 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2674 uint worker_id,
2675 uint no_of_par_workers,
2676 jint claim_value) {
2677 const uint regions = n_regions();
2678 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2679 no_of_par_workers :
2680 1);
2681 assert(UseDynamicNumberOfGCThreads ||
2682 no_of_par_workers == workers()->total_workers(),
2683 "Non dynamic should use fixed number of workers");
2684 // try to spread out the starting points of the workers
2685 const HeapRegion* start_hr =
2686 start_region_for_worker(worker_id, no_of_par_workers);
2687 const uint start_index = start_hr->hrs_index();
2688
2689 // each worker will actually look at all regions
2690 for (uint count = 0; count < regions; ++count) {
2691 const uint index = (start_index + count) % regions;
2692 assert(0 <= index && index < regions, "sanity");
2693 HeapRegion* r = region_at(index);
2694 // we'll ignore "continues humongous" regions (we'll process them
2695 // when we come across their corresponding "start humongous"
2696 // region) and regions already claimed
2697 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2698 continue;
2699 }
2700 // OK, try to claim it
2701 if (r->claimHeapRegion(claim_value)) {
2702 // success!
2703 assert(!r->continuesHumongous(), "sanity");
2704 if (r->startsHumongous()) {
2705 // If the region is "starts humongous" we'll iterate over its
2706 // "continues humongous" first; in fact we'll do them
2707 // first. The order is important. In on case, calling the
2708 // closure on the "starts humongous" region might de-allocate
2709 // and clear all its "continues humongous" regions and, as a
2710 // result, we might end up processing them twice. So, we'll do
2711 // them first (notice: most closures will ignore them anyway) and
2712 // then we'll do the "starts humongous" region.
2713 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2714 HeapRegion* chr = region_at(ch_index);
2715
2716 // if the region has already been claimed or it's not
2717 // "continues humongous" we're done
2718 if (chr->claim_value() == claim_value ||
2719 !chr->continuesHumongous()) {
2720 break;
2721 }
2722
2723 // No one should have claimed it directly. We can given
2724 // that we claimed its "starts humongous" region.
2725 assert(chr->claim_value() != claim_value, "sanity");
2726 assert(chr->humongous_start_region() == r, "sanity");
2727
2728 if (chr->claimHeapRegion(claim_value)) {
2729 // we should always be able to claim it; no one else should
2730 // be trying to claim this region
2731
2732 bool res2 = cl->doHeapRegion(chr);
2733 assert(!res2, "Should not abort");
2734
2735 // Right now, this holds (i.e., no closure that actually
2736 // does something with "continues humongous" regions
2737 // clears them). We might have to weaken it in the future,
2738 // but let's leave these two asserts here for extra safety.
2739 assert(chr->continuesHumongous(), "should still be the case");
2740 assert(chr->humongous_start_region() == r, "sanity");
2741 } else {
2742 guarantee(false, "we should not reach here");
2743 }
2744 }
2745 }
2746
2747 assert(!r->continuesHumongous(), "sanity");
2748 bool res = cl->doHeapRegion(r);
2749 assert(!res, "Should not abort");
2750 }
2751 }
2752 }
2753
2754 class ResetClaimValuesClosure: public HeapRegionClosure {
2755 public:
2756 bool doHeapRegion(HeapRegion* r) {
2757 r->set_claim_value(HeapRegion::InitialClaimValue);
2758 return false;
2759 }
2760 };
2761
2762 void G1CollectedHeap::reset_heap_region_claim_values() {
2763 ResetClaimValuesClosure blk;
2764 heap_region_iterate(&blk);
2765 }
2766
2767 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2768 ResetClaimValuesClosure blk;
2769 collection_set_iterate(&blk);
2770 }
2771
2772 #ifdef ASSERT
2773 // This checks whether all regions in the heap have the correct claim
2774 // value. I also piggy-backed on this a check to ensure that the
2775 // humongous_start_region() information on "continues humongous"
2776 // regions is correct.
2777
2778 class CheckClaimValuesClosure : public HeapRegionClosure {
2779 private:
2780 jint _claim_value;
2781 uint _failures;
2782 HeapRegion* _sh_region;
2783
2784 public:
2785 CheckClaimValuesClosure(jint claim_value) :
2786 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2787 bool doHeapRegion(HeapRegion* r) {
2788 if (r->claim_value() != _claim_value) {
2789 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2790 "claim value = %d, should be %d",
2791 HR_FORMAT_PARAMS(r),
2792 r->claim_value(), _claim_value);
2793 ++_failures;
2794 }
2795 if (!r->isHumongous()) {
2796 _sh_region = NULL;
2797 } else if (r->startsHumongous()) {
2798 _sh_region = r;
2799 } else if (r->continuesHumongous()) {
2800 if (r->humongous_start_region() != _sh_region) {
2801 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2802 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2803 HR_FORMAT_PARAMS(r),
2804 r->humongous_start_region(),
2805 _sh_region);
2806 ++_failures;
2807 }
2808 }
2809 return false;
2810 }
2811 uint failures() { return _failures; }
2812 };
2813
2814 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2815 CheckClaimValuesClosure cl(claim_value);
2816 heap_region_iterate(&cl);
2817 return cl.failures() == 0;
2818 }
2819
2820 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2821 private:
2822 jint _claim_value;
2823 uint _failures;
2824
2825 public:
2826 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2827 _claim_value(claim_value), _failures(0) { }
2828
2829 uint failures() { return _failures; }
2830
2831 bool doHeapRegion(HeapRegion* hr) {
2832 assert(hr->in_collection_set(), "how?");
2833 assert(!hr->isHumongous(), "H-region in CSet");
2834 if (hr->claim_value() != _claim_value) {
2835 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2836 "claim value = %d, should be %d",
2837 HR_FORMAT_PARAMS(hr),
2838 hr->claim_value(), _claim_value);
2839 _failures += 1;
2840 }
2841 return false;
2842 }
2843 };
2844
2845 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2846 CheckClaimValuesInCSetHRClosure cl(claim_value);
2847 collection_set_iterate(&cl);
2848 return cl.failures() == 0;
2849 }
2850 #endif // ASSERT
2851
2852 // Clear the cached CSet starting regions and (more importantly)
2853 // the time stamps. Called when we reset the GC time stamp.
2854 void G1CollectedHeap::clear_cset_start_regions() {
2855 assert(_worker_cset_start_region != NULL, "sanity");
2856 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2857
2858 int n_queues = MAX2((int)ParallelGCThreads, 1);
2859 for (int i = 0; i < n_queues; i++) {
2860 _worker_cset_start_region[i] = NULL;
2861 _worker_cset_start_region_time_stamp[i] = 0;
2862 }
2863 }
2864
2865 // Given the id of a worker, obtain or calculate a suitable
2866 // starting region for iterating over the current collection set.
2867 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2868 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2869
2870 HeapRegion* result = NULL;
2871 unsigned gc_time_stamp = get_gc_time_stamp();
2872
2873 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2874 // Cached starting region for current worker was set
2875 // during the current pause - so it's valid.
2876 // Note: the cached starting heap region may be NULL
2877 // (when the collection set is empty).
2878 result = _worker_cset_start_region[worker_i];
2879 assert(result == NULL || result->in_collection_set(), "sanity");
2880 return result;
2881 }
2882
2883 // The cached entry was not valid so let's calculate
2884 // a suitable starting heap region for this worker.
2885
2886 // We want the parallel threads to start their collection
2887 // set iteration at different collection set regions to
2888 // avoid contention.
2889 // If we have:
2890 // n collection set regions
2891 // p threads
2892 // Then thread t will start at region floor ((t * n) / p)
2893
2894 result = g1_policy()->collection_set();
2895 if (G1CollectedHeap::use_parallel_gc_threads()) {
2896 uint cs_size = g1_policy()->cset_region_length();
2897 uint active_workers = workers()->active_workers();
2898 assert(UseDynamicNumberOfGCThreads ||
2899 active_workers == workers()->total_workers(),
2900 "Unless dynamic should use total workers");
2901
2902 uint end_ind = (cs_size * worker_i) / active_workers;
2903 uint start_ind = 0;
2904
2905 if (worker_i > 0 &&
2906 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2907 // Previous workers starting region is valid
2908 // so let's iterate from there
2909 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2910 result = _worker_cset_start_region[worker_i - 1];
2911 }
2912
2913 for (uint i = start_ind; i < end_ind; i++) {
2914 result = result->next_in_collection_set();
2915 }
2916 }
2917
2918 // Note: the calculated starting heap region may be NULL
2919 // (when the collection set is empty).
2920 assert(result == NULL || result->in_collection_set(), "sanity");
2921 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2922 "should be updated only once per pause");
2923 _worker_cset_start_region[worker_i] = result;
2924 OrderAccess::storestore();
2925 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2926 return result;
2927 }
2928
2929 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2930 uint no_of_par_workers) {
2931 uint worker_num =
2932 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2933 assert(UseDynamicNumberOfGCThreads ||
2934 no_of_par_workers == workers()->total_workers(),
2935 "Non dynamic should use fixed number of workers");
2936 const uint start_index = n_regions() * worker_i / worker_num;
2937 return region_at(start_index);
2938 }
2939
2940 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2941 HeapRegion* r = g1_policy()->collection_set();
2942 while (r != NULL) {
2943 HeapRegion* next = r->next_in_collection_set();
2944 if (cl->doHeapRegion(r)) {
2945 cl->incomplete();
2946 return;
2947 }
2948 r = next;
2949 }
2950 }
2951
2952 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2953 HeapRegionClosure *cl) {
2954 if (r == NULL) {
2955 // The CSet is empty so there's nothing to do.
2956 return;
2957 }
2958
2959 assert(r->in_collection_set(),
2960 "Start region must be a member of the collection set.");
2961 HeapRegion* cur = r;
2962 while (cur != NULL) {
2963 HeapRegion* next = cur->next_in_collection_set();
2964 if (cl->doHeapRegion(cur) && false) {
2965 cl->incomplete();
2966 return;
2967 }
2968 cur = next;
2969 }
2970 cur = g1_policy()->collection_set();
2971 while (cur != r) {
2972 HeapRegion* next = cur->next_in_collection_set();
2973 if (cl->doHeapRegion(cur) && false) {
2974 cl->incomplete();
2975 return;
2976 }
2977 cur = next;
2978 }
2979 }
2980
2981 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2982 return n_regions() > 0 ? region_at(0) : NULL;
2983 }
2984
2985
2986 Space* G1CollectedHeap::space_containing(const void* addr) const {
2987 Space* res = heap_region_containing(addr);
2988 return res;
2989 }
2990
2991 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2992 Space* sp = space_containing(addr);
2993 if (sp != NULL) {
2994 return sp->block_start(addr);
2995 }
2996 return NULL;
2997 }
2998
2999 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3000 Space* sp = space_containing(addr);
3001 assert(sp != NULL, "block_size of address outside of heap");
3002 return sp->block_size(addr);
3003 }
3004
3005 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3006 Space* sp = space_containing(addr);
3007 return sp->block_is_obj(addr);
3008 }
3009
3010 bool G1CollectedHeap::supports_tlab_allocation() const {
3011 return true;
3012 }
3013
3014 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3015 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
3016 }
3017
3018 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3019 return young_list()->eden_used_bytes();
3020 }
3021
3022 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3023 // must be smaller than the humongous object limit.
3024 size_t G1CollectedHeap::max_tlab_size() const {
3025 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3026 }
3027
3028 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3029 // Return the remaining space in the cur alloc region, but not less than
3030 // the min TLAB size.
3031
3032 // Also, this value can be at most the humongous object threshold,
3033 // since we can't allow tlabs to grow big enough to accommodate
3034 // humongous objects.
3035
3036 HeapRegion* hr = _mutator_alloc_region.get();
3037 size_t max_tlab = max_tlab_size() * wordSize;
3038 if (hr == NULL) {
3039 return max_tlab;
3040 } else {
3041 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3042 }
3043 }
3044
3045 size_t G1CollectedHeap::max_capacity() const {
3046 return _g1_reserved.byte_size();
3047 }
3048
3049 jlong G1CollectedHeap::millis_since_last_gc() {
3050 // assert(false, "NYI");
3051 return 0;
3052 }
3053
3054 void G1CollectedHeap::prepare_for_verify() {
3055 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3056 ensure_parsability(false);
3057 }
3058 g1_rem_set()->prepare_for_verify();
3059 }
3060
3061 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3062 VerifyOption vo) {
3063 switch (vo) {
3064 case VerifyOption_G1UsePrevMarking:
3065 return hr->obj_allocated_since_prev_marking(obj);
3066 case VerifyOption_G1UseNextMarking:
3067 return hr->obj_allocated_since_next_marking(obj);
3068 case VerifyOption_G1UseMarkWord:
3069 return false;
3070 default:
3071 ShouldNotReachHere();
3072 }
3073 return false; // keep some compilers happy
3074 }
3075
3076 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3077 switch (vo) {
3078 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3079 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3080 case VerifyOption_G1UseMarkWord: return NULL;
3081 default: ShouldNotReachHere();
3082 }
3083 return NULL; // keep some compilers happy
3084 }
3085
3086 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3087 switch (vo) {
3088 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3089 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3090 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3091 default: ShouldNotReachHere();
3092 }
3093 return false; // keep some compilers happy
3094 }
3095
3096 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3097 switch (vo) {
3098 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3099 case VerifyOption_G1UseNextMarking: return "NTAMS";
3100 case VerifyOption_G1UseMarkWord: return "NONE";
3101 default: ShouldNotReachHere();
3102 }
3103 return NULL; // keep some compilers happy
3104 }
3105
3106 class VerifyRootsClosure: public OopClosure {
3107 private:
3108 G1CollectedHeap* _g1h;
3109 VerifyOption _vo;
3110 bool _failures;
3111 public:
3112 // _vo == UsePrevMarking -> use "prev" marking information,
3113 // _vo == UseNextMarking -> use "next" marking information,
3114 // _vo == UseMarkWord -> use mark word from object header.
3115 VerifyRootsClosure(VerifyOption vo) :
3116 _g1h(G1CollectedHeap::heap()),
3117 _vo(vo),
3118 _failures(false) { }
3119
3120 bool failures() { return _failures; }
3121
3122 template <class T> void do_oop_nv(T* p) {
3123 T heap_oop = oopDesc::load_heap_oop(p);
3124 if (!oopDesc::is_null(heap_oop)) {
3125 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3126 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3127 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3128 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3129 if (_vo == VerifyOption_G1UseMarkWord) {
3130 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3131 }
3132 obj->print_on(gclog_or_tty);
3133 _failures = true;
3134 }
3135 }
3136 }
3137
3138 void do_oop(oop* p) { do_oop_nv(p); }
3139 void do_oop(narrowOop* p) { do_oop_nv(p); }
3140 };
3141
3142 class G1VerifyCodeRootOopClosure: public OopClosure {
3143 G1CollectedHeap* _g1h;
3144 OopClosure* _root_cl;
3145 nmethod* _nm;
3146 VerifyOption _vo;
3147 bool _failures;
3148
3149 template <class T> void do_oop_work(T* p) {
3150 // First verify that this root is live
3151 _root_cl->do_oop(p);
3152
3153 if (!G1VerifyHeapRegionCodeRoots) {
3154 // We're not verifying the code roots attached to heap region.
3155 return;
3156 }
3157
3158 // Don't check the code roots during marking verification in a full GC
3159 if (_vo == VerifyOption_G1UseMarkWord) {
3160 return;
3161 }
3162
3163 // Now verify that the current nmethod (which contains p) is
3164 // in the code root list of the heap region containing the
3165 // object referenced by p.
3166
3167 T heap_oop = oopDesc::load_heap_oop(p);
3168 if (!oopDesc::is_null(heap_oop)) {
3169 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3170
3171 // Now fetch the region containing the object
3172 HeapRegion* hr = _g1h->heap_region_containing(obj);
3173 HeapRegionRemSet* hrrs = hr->rem_set();
3174 // Verify that the strong code root list for this region
3175 // contains the nmethod
3176 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3177 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3178 "from nmethod "PTR_FORMAT" not in strong "
3179 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3180 p, _nm, hr->bottom(), hr->end());
3181 _failures = true;
3182 }
3183 }
3184 }
3185
3186 public:
3187 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3188 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3189
3190 void do_oop(oop* p) { do_oop_work(p); }
3191 void do_oop(narrowOop* p) { do_oop_work(p); }
3192
3193 void set_nmethod(nmethod* nm) { _nm = nm; }
3194 bool failures() { return _failures; }
3195 };
3196
3197 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3198 G1VerifyCodeRootOopClosure* _oop_cl;
3199
3200 public:
3201 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3202 _oop_cl(oop_cl) {}
3203
3204 void do_code_blob(CodeBlob* cb) {
3205 nmethod* nm = cb->as_nmethod_or_null();
3206 if (nm != NULL) {
3207 _oop_cl->set_nmethod(nm);
3208 nm->oops_do(_oop_cl);
3209 }
3210 }
3211 };
3212
3213 class YoungRefCounterClosure : public OopClosure {
3214 G1CollectedHeap* _g1h;
3215 int _count;
3216 public:
3217 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3218 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3219 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3220
3221 int count() { return _count; }
3222 void reset_count() { _count = 0; };
3223 };
3224
3225 class VerifyKlassClosure: public KlassClosure {
3226 YoungRefCounterClosure _young_ref_counter_closure;
3227 OopClosure *_oop_closure;
3228 public:
3229 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3230 void do_klass(Klass* k) {
3231 k->oops_do(_oop_closure);
3232
3233 _young_ref_counter_closure.reset_count();
3234 k->oops_do(&_young_ref_counter_closure);
3235 if (_young_ref_counter_closure.count() > 0) {
3236 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3237 }
3238 }
3239 };
3240
3241 class VerifyLivenessOopClosure: public OopClosure {
3242 G1CollectedHeap* _g1h;
3243 VerifyOption _vo;
3244 public:
3245 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3246 _g1h(g1h), _vo(vo)
3247 { }
3248 void do_oop(narrowOop *p) { do_oop_work(p); }
3249 void do_oop( oop *p) { do_oop_work(p); }
3250
3251 template <class T> void do_oop_work(T *p) {
3252 oop obj = oopDesc::load_decode_heap_oop(p);
3253 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3254 "Dead object referenced by a not dead object");
3255 }
3256 };
3257
3258 class VerifyObjsInRegionClosure: public ObjectClosure {
3259 private:
3260 G1CollectedHeap* _g1h;
3261 size_t _live_bytes;
3262 HeapRegion *_hr;
3263 VerifyOption _vo;
3264 public:
3265 // _vo == UsePrevMarking -> use "prev" marking information,
3266 // _vo == UseNextMarking -> use "next" marking information,
3267 // _vo == UseMarkWord -> use mark word from object header.
3268 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3269 : _live_bytes(0), _hr(hr), _vo(vo) {
3270 _g1h = G1CollectedHeap::heap();
3271 }
3272 void do_object(oop o) {
3273 VerifyLivenessOopClosure isLive(_g1h, _vo);
3274 assert(o != NULL, "Huh?");
3275 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3276 // If the object is alive according to the mark word,
3277 // then verify that the marking information agrees.
3278 // Note we can't verify the contra-positive of the
3279 // above: if the object is dead (according to the mark
3280 // word), it may not be marked, or may have been marked
3281 // but has since became dead, or may have been allocated
3282 // since the last marking.
3283 if (_vo == VerifyOption_G1UseMarkWord) {
3284 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3285 }
3286
3287 o->oop_iterate_no_header(&isLive);
3288 if (!_hr->obj_allocated_since_prev_marking(o)) {
3289 size_t obj_size = o->size(); // Make sure we don't overflow
3290 _live_bytes += (obj_size * HeapWordSize);
3291 }
3292 }
3293 }
3294 size_t live_bytes() { return _live_bytes; }
3295 };
3296
3297 class PrintObjsInRegionClosure : public ObjectClosure {
3298 HeapRegion *_hr;
3299 G1CollectedHeap *_g1;
3300 public:
3301 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3302 _g1 = G1CollectedHeap::heap();
3303 };
3304
3305 void do_object(oop o) {
3306 if (o != NULL) {
3307 HeapWord *start = (HeapWord *) o;
3308 size_t word_sz = o->size();
3309 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3310 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3311 (void*) o, word_sz,
3312 _g1->isMarkedPrev(o),
3313 _g1->isMarkedNext(o),
3314 _hr->obj_allocated_since_prev_marking(o));
3315 HeapWord *end = start + word_sz;
3316 HeapWord *cur;
3317 int *val;
3318 for (cur = start; cur < end; cur++) {
3319 val = (int *) cur;
3320 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3321 }
3322 }
3323 }
3324 };
3325
3326 class VerifyRegionClosure: public HeapRegionClosure {
3327 private:
3328 bool _par;
3329 VerifyOption _vo;
3330 bool _failures;
3331 public:
3332 // _vo == UsePrevMarking -> use "prev" marking information,
3333 // _vo == UseNextMarking -> use "next" marking information,
3334 // _vo == UseMarkWord -> use mark word from object header.
3335 VerifyRegionClosure(bool par, VerifyOption vo)
3336 : _par(par),
3337 _vo(vo),
3338 _failures(false) {}
3339
3340 bool failures() {
3341 return _failures;
3342 }
3343
3344 bool doHeapRegion(HeapRegion* r) {
3345 if (!r->continuesHumongous()) {
3346 bool failures = false;
3347 r->verify(_vo, &failures);
3348 if (failures) {
3349 _failures = true;
3350 } else {
3351 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3352 r->object_iterate(¬_dead_yet_cl);
3353 if (_vo != VerifyOption_G1UseNextMarking) {
3354 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3355 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3356 "max_live_bytes "SIZE_FORMAT" "
3357 "< calculated "SIZE_FORMAT,
3358 r->bottom(), r->end(),
3359 r->max_live_bytes(),
3360 not_dead_yet_cl.live_bytes());
3361 _failures = true;
3362 }
3363 } else {
3364 // When vo == UseNextMarking we cannot currently do a sanity
3365 // check on the live bytes as the calculation has not been
3366 // finalized yet.
3367 }
3368 }
3369 }
3370 return false; // stop the region iteration if we hit a failure
3371 }
3372 };
3373
3374 // This is the task used for parallel verification of the heap regions
3375
3376 class G1ParVerifyTask: public AbstractGangTask {
3377 private:
3378 G1CollectedHeap* _g1h;
3379 VerifyOption _vo;
3380 bool _failures;
3381
3382 public:
3383 // _vo == UsePrevMarking -> use "prev" marking information,
3384 // _vo == UseNextMarking -> use "next" marking information,
3385 // _vo == UseMarkWord -> use mark word from object header.
3386 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3387 AbstractGangTask("Parallel verify task"),
3388 _g1h(g1h),
3389 _vo(vo),
3390 _failures(false) { }
3391
3392 bool failures() {
3393 return _failures;
3394 }
3395
3396 void work(uint worker_id) {
3397 HandleMark hm;
3398 VerifyRegionClosure blk(true, _vo);
3399 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3400 _g1h->workers()->active_workers(),
3401 HeapRegion::ParVerifyClaimValue);
3402 if (blk.failures()) {
3403 _failures = true;
3404 }
3405 }
3406 };
3407
3408 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3409 if (SafepointSynchronize::is_at_safepoint()) {
3410 assert(Thread::current()->is_VM_thread(),
3411 "Expected to be executed serially by the VM thread at this point");
3412
3413 if (!silent) { gclog_or_tty->print("Roots "); }
3414 VerifyRootsClosure rootsCl(vo);
3415 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3416 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3417 VerifyKlassClosure klassCl(this, &rootsCl);
3418
3419 // We apply the relevant closures to all the oops in the
3420 // system dictionary, the string table and the code cache.
3421 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3422
3423 // Need cleared claim bits for the strong roots processing
3424 ClassLoaderDataGraph::clear_claimed_marks();
3425
3426 process_strong_roots(true, // activate StrongRootsScope
3427 false, // we set "is scavenging" to false,
3428 // so we don't reset the dirty cards.
3429 ScanningOption(so), // roots scanning options
3430 &rootsCl,
3431 &blobsCl,
3432 &klassCl
3433 );
3434
3435 bool failures = rootsCl.failures() || codeRootsCl.failures();
3436
3437 if (vo != VerifyOption_G1UseMarkWord) {
3438 // If we're verifying during a full GC then the region sets
3439 // will have been torn down at the start of the GC. Therefore
3440 // verifying the region sets will fail. So we only verify
3441 // the region sets when not in a full GC.
3442 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3443 verify_region_sets();
3444 }
3445
3446 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3447 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3448 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3449 "sanity check");
3450
3451 G1ParVerifyTask task(this, vo);
3452 assert(UseDynamicNumberOfGCThreads ||
3453 workers()->active_workers() == workers()->total_workers(),
3454 "If not dynamic should be using all the workers");
3455 int n_workers = workers()->active_workers();
3456 set_par_threads(n_workers);
3457 workers()->run_task(&task);
3458 set_par_threads(0);
3459 if (task.failures()) {
3460 failures = true;
3461 }
3462
3463 // Checks that the expected amount of parallel work was done.
3464 // The implication is that n_workers is > 0.
3465 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3466 "sanity check");
3467
3468 reset_heap_region_claim_values();
3469
3470 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3471 "sanity check");
3472 } else {
3473 VerifyRegionClosure blk(false, vo);
3474 heap_region_iterate(&blk);
3475 if (blk.failures()) {
3476 failures = true;
3477 }
3478 }
3479 if (!silent) gclog_or_tty->print("RemSet ");
3480 rem_set()->verify();
3481
3482 if (failures) {
3483 gclog_or_tty->print_cr("Heap:");
3484 // It helps to have the per-region information in the output to
3485 // help us track down what went wrong. This is why we call
3486 // print_extended_on() instead of print_on().
3487 print_extended_on(gclog_or_tty);
3488 gclog_or_tty->print_cr("");
3489 #ifndef PRODUCT
3490 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3491 concurrent_mark()->print_reachable("at-verification-failure",
3492 vo, false /* all */);
3493 }
3494 #endif
3495 gclog_or_tty->flush();
3496 }
3497 guarantee(!failures, "there should not have been any failures");
3498 } else {
3499 if (!silent)
3500 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3501 }
3502 }
3503
3504 void G1CollectedHeap::verify(bool silent) {
3505 verify(silent, VerifyOption_G1UsePrevMarking);
3506 }
3507
3508 double G1CollectedHeap::verify(bool guard, const char* msg) {
3509 double verify_time_ms = 0.0;
3510
3511 if (guard && total_collections() >= VerifyGCStartAt) {
3512 double verify_start = os::elapsedTime();
3513 HandleMark hm; // Discard invalid handles created during verification
3514 prepare_for_verify();
3515 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3516 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3517 }
3518
3519 return verify_time_ms;
3520 }
3521
3522 void G1CollectedHeap::verify_before_gc() {
3523 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3524 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3525 }
3526
3527 void G1CollectedHeap::verify_after_gc() {
3528 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3529 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3530 }
3531
3532 class PrintRegionClosure: public HeapRegionClosure {
3533 outputStream* _st;
3534 public:
3535 PrintRegionClosure(outputStream* st) : _st(st) {}
3536 bool doHeapRegion(HeapRegion* r) {
3537 r->print_on(_st);
3538 return false;
3539 }
3540 };
3541
3542 void G1CollectedHeap::print_on(outputStream* st) const {
3543 st->print(" %-20s", "garbage-first heap");
3544 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3545 capacity()/K, used_unlocked()/K);
3546 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3547 _g1_storage.low_boundary(),
3548 _g1_storage.high(),
3549 _g1_storage.high_boundary());
3550 st->cr();
3551 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3552 uint young_regions = _young_list->length();
3553 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3554 (size_t) young_regions * HeapRegion::GrainBytes / K);
3555 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3556 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3557 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3558 st->cr();
3559 MetaspaceAux::print_on(st);
3560 }
3561
3562 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3563 print_on(st);
3564
3565 // Print the per-region information.
3566 st->cr();
3567 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3568 "HS=humongous(starts), HC=humongous(continues), "
3569 "CS=collection set, F=free, TS=gc time stamp, "
3570 "PTAMS=previous top-at-mark-start, "
3571 "NTAMS=next top-at-mark-start)");
3572 PrintRegionClosure blk(st);
3573 heap_region_iterate(&blk);
3574 }
3575
3576 void G1CollectedHeap::print_on_error(outputStream* st) const {
3577 this->CollectedHeap::print_on_error(st);
3578
3579 if (_cm != NULL) {
3580 st->cr();
3581 _cm->print_on_error(st);
3582 }
3583 }
3584
3585 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3586 if (G1CollectedHeap::use_parallel_gc_threads()) {
3587 workers()->print_worker_threads_on(st);
3588 }
3589 _cmThread->print_on(st);
3590 st->cr();
3591 _cm->print_worker_threads_on(st);
3592 _cg1r->print_worker_threads_on(st);
3593 }
3594
3595 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3596 if (G1CollectedHeap::use_parallel_gc_threads()) {
3597 workers()->threads_do(tc);
3598 }
3599 tc->do_thread(_cmThread);
3600 _cg1r->threads_do(tc);
3601 }
3602
3603 void G1CollectedHeap::print_tracing_info() const {
3604 // We'll overload this to mean "trace GC pause statistics."
3605 if (TraceGen0Time || TraceGen1Time) {
3606 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3607 // to that.
3608 g1_policy()->print_tracing_info();
3609 }
3610 if (G1SummarizeRSetStats) {
3611 g1_rem_set()->print_summary_info();
3612 }
3613 if (G1SummarizeConcMark) {
3614 concurrent_mark()->print_summary_info();
3615 }
3616 g1_policy()->print_yg_surv_rate_info();
3617 SpecializationStats::print();
3618 }
3619
3620 #ifndef PRODUCT
3621 // Helpful for debugging RSet issues.
3622
3623 class PrintRSetsClosure : public HeapRegionClosure {
3624 private:
3625 const char* _msg;
3626 size_t _occupied_sum;
3627
3628 public:
3629 bool doHeapRegion(HeapRegion* r) {
3630 HeapRegionRemSet* hrrs = r->rem_set();
3631 size_t occupied = hrrs->occupied();
3632 _occupied_sum += occupied;
3633
3634 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3635 HR_FORMAT_PARAMS(r));
3636 if (occupied == 0) {
3637 gclog_or_tty->print_cr(" RSet is empty");
3638 } else {
3639 hrrs->print();
3640 }
3641 gclog_or_tty->print_cr("----------");
3642 return false;
3643 }
3644
3645 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3646 gclog_or_tty->cr();
3647 gclog_or_tty->print_cr("========================================");
3648 gclog_or_tty->print_cr(msg);
3649 gclog_or_tty->cr();
3650 }
3651
3652 ~PrintRSetsClosure() {
3653 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3654 gclog_or_tty->print_cr("========================================");
3655 gclog_or_tty->cr();
3656 }
3657 };
3658
3659 void G1CollectedHeap::print_cset_rsets() {
3660 PrintRSetsClosure cl("Printing CSet RSets");
3661 collection_set_iterate(&cl);
3662 }
3663
3664 void G1CollectedHeap::print_all_rsets() {
3665 PrintRSetsClosure cl("Printing All RSets");;
3666 heap_region_iterate(&cl);
3667 }
3668 #endif // PRODUCT
3669
3670 G1CollectedHeap* G1CollectedHeap::heap() {
3671 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3672 "not a garbage-first heap");
3673 return _g1h;
3674 }
3675
3676 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3677 // always_do_update_barrier = false;
3678 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3679 // Fill TLAB's and such
3680 accumulate_statistics_all_tlabs();
3681 ensure_parsability(true);
3682
3683 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3684 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3685 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3686 }
3687 }
3688
3689 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3690
3691 if (G1SummarizeRSetStats &&
3692 (G1SummarizeRSetStatsPeriod > 0) &&
3693 // we are at the end of the GC. Total collections has already been increased.
3694 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3695 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3696 }
3697
3698 // FIXME: what is this about?
3699 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3700 // is set.
3701 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3702 "derived pointer present"));
3703 // always_do_update_barrier = true;
3704
3705 resize_all_tlabs();
3706
3707 // We have just completed a GC. Update the soft reference
3708 // policy with the new heap occupancy
3709 Universe::update_heap_info_at_gc();
3710 }
3711
3712 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3713 unsigned int gc_count_before,
3714 bool* succeeded,
3715 GCCause::Cause gc_cause) {
3716 assert_heap_not_locked_and_not_at_safepoint();
3717 g1_policy()->record_stop_world_start();
3718 VM_G1IncCollectionPause op(gc_count_before,
3719 word_size,
3720 false, /* should_initiate_conc_mark */
3721 g1_policy()->max_pause_time_ms(),
3722 gc_cause);
3723 VMThread::execute(&op);
3724
3725 HeapWord* result = op.result();
3726 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3727 assert(result == NULL || ret_succeeded,
3728 "the result should be NULL if the VM did not succeed");
3729 *succeeded = ret_succeeded;
3730
3731 assert_heap_not_locked();
3732 return result;
3733 }
3734
3735 void
3736 G1CollectedHeap::doConcurrentMark() {
3737 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3738 if (!_cmThread->in_progress()) {
3739 _cmThread->set_started();
3740 CGC_lock->notify();
3741 }
3742 }
3743
3744 size_t G1CollectedHeap::pending_card_num() {
3745 size_t extra_cards = 0;
3746 JavaThread *curr = Threads::first();
3747 while (curr != NULL) {
3748 DirtyCardQueue& dcq = curr->dirty_card_queue();
3749 extra_cards += dcq.size();
3750 curr = curr->next();
3751 }
3752 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3753 size_t buffer_size = dcqs.buffer_size();
3754 size_t buffer_num = dcqs.completed_buffers_num();
3755
3756 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3757 // in bytes - not the number of 'entries'. We need to convert
3758 // into a number of cards.
3759 return (buffer_size * buffer_num + extra_cards) / oopSize;
3760 }
3761
3762 size_t G1CollectedHeap::cards_scanned() {
3763 return g1_rem_set()->cardsScanned();
3764 }
3765
3766 void
3767 G1CollectedHeap::setup_surviving_young_words() {
3768 assert(_surviving_young_words == NULL, "pre-condition");
3769 uint array_length = g1_policy()->young_cset_region_length();
3770 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3771 if (_surviving_young_words == NULL) {
3772 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3773 "Not enough space for young surv words summary.");
3774 }
3775 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3776 #ifdef ASSERT
3777 for (uint i = 0; i < array_length; ++i) {
3778 assert( _surviving_young_words[i] == 0, "memset above" );
3779 }
3780 #endif // !ASSERT
3781 }
3782
3783 void
3784 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3785 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3786 uint array_length = g1_policy()->young_cset_region_length();
3787 for (uint i = 0; i < array_length; ++i) {
3788 _surviving_young_words[i] += surv_young_words[i];
3789 }
3790 }
3791
3792 void
3793 G1CollectedHeap::cleanup_surviving_young_words() {
3794 guarantee( _surviving_young_words != NULL, "pre-condition" );
3795 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3796 _surviving_young_words = NULL;
3797 }
3798
3799 #ifdef ASSERT
3800 class VerifyCSetClosure: public HeapRegionClosure {
3801 public:
3802 bool doHeapRegion(HeapRegion* hr) {
3803 // Here we check that the CSet region's RSet is ready for parallel
3804 // iteration. The fields that we'll verify are only manipulated
3805 // when the region is part of a CSet and is collected. Afterwards,
3806 // we reset these fields when we clear the region's RSet (when the
3807 // region is freed) so they are ready when the region is
3808 // re-allocated. The only exception to this is if there's an
3809 // evacuation failure and instead of freeing the region we leave
3810 // it in the heap. In that case, we reset these fields during
3811 // evacuation failure handling.
3812 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3813
3814 // Here's a good place to add any other checks we'd like to
3815 // perform on CSet regions.
3816 return false;
3817 }
3818 };
3819 #endif // ASSERT
3820
3821 #if TASKQUEUE_STATS
3822 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3823 st->print_raw_cr("GC Task Stats");
3824 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3825 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3826 }
3827
3828 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3829 print_taskqueue_stats_hdr(st);
3830
3831 TaskQueueStats totals;
3832 const int n = workers() != NULL ? workers()->total_workers() : 1;
3833 for (int i = 0; i < n; ++i) {
3834 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3835 totals += task_queue(i)->stats;
3836 }
3837 st->print_raw("tot "); totals.print(st); st->cr();
3838
3839 DEBUG_ONLY(totals.verify());
3840 }
3841
3842 void G1CollectedHeap::reset_taskqueue_stats() {
3843 const int n = workers() != NULL ? workers()->total_workers() : 1;
3844 for (int i = 0; i < n; ++i) {
3845 task_queue(i)->stats.reset();
3846 }
3847 }
3848 #endif // TASKQUEUE_STATS
3849
3850 void G1CollectedHeap::log_gc_header() {
3851 if (!G1Log::fine()) {
3852 return;
3853 }
3854
3855 gclog_or_tty->date_stamp(PrintGCDateStamps);
3856 gclog_or_tty->stamp(PrintGCTimeStamps);
3857
3858 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3859 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3860 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3861
3862 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3863 }
3864
3865 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3866 if (!G1Log::fine()) {
3867 return;
3868 }
3869
3870 if (G1Log::finer()) {
3871 if (evacuation_failed()) {
3872 gclog_or_tty->print(" (to-space exhausted)");
3873 }
3874 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3875 g1_policy()->phase_times()->note_gc_end();
3876 g1_policy()->phase_times()->print(pause_time_sec);
3877 g1_policy()->print_detailed_heap_transition();
3878 } else {
3879 if (evacuation_failed()) {
3880 gclog_or_tty->print("--");
3881 }
3882 g1_policy()->print_heap_transition();
3883 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3884 }
3885 gclog_or_tty->flush();
3886 }
3887
3888 bool
3889 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3890 assert_at_safepoint(true /* should_be_vm_thread */);
3891 guarantee(!is_gc_active(), "collection is not reentrant");
3892
3893 if (GC_locker::check_active_before_gc()) {
3894 return false;
3895 }
3896
3897 _gc_timer_stw->register_gc_start();
3898
3899 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3900
3901 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3902 ResourceMark rm;
3903
3904 print_heap_before_gc();
3905 trace_heap_before_gc(_gc_tracer_stw);
3906
3907 verify_region_sets_optional();
3908 verify_dirty_young_regions();
3909
3910 // This call will decide whether this pause is an initial-mark
3911 // pause. If it is, during_initial_mark_pause() will return true
3912 // for the duration of this pause.
3913 g1_policy()->decide_on_conc_mark_initiation();
3914
3915 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3916 assert(!g1_policy()->during_initial_mark_pause() ||
3917 g1_policy()->gcs_are_young(), "sanity");
3918
3919 // We also do not allow mixed GCs during marking.
3920 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3921
3922 // Record whether this pause is an initial mark. When the current
3923 // thread has completed its logging output and it's safe to signal
3924 // the CM thread, the flag's value in the policy has been reset.
3925 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3926
3927 // Inner scope for scope based logging, timers, and stats collection
3928 {
3929 EvacuationInfo evacuation_info;
3930
3931 if (g1_policy()->during_initial_mark_pause()) {
3932 // We are about to start a marking cycle, so we increment the
3933 // full collection counter.
3934 increment_old_marking_cycles_started();
3935 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3936 }
3937
3938 _gc_tracer_stw->report_yc_type(yc_type());
3939
3940 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3941
3942 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3943 workers()->active_workers() : 1);
3944 double pause_start_sec = os::elapsedTime();
3945 g1_policy()->phase_times()->note_gc_start(active_workers);
3946 log_gc_header();
3947
3948 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3949 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3950
3951 // If the secondary_free_list is not empty, append it to the
3952 // free_list. No need to wait for the cleanup operation to finish;
3953 // the region allocation code will check the secondary_free_list
3954 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3955 // set, skip this step so that the region allocation code has to
3956 // get entries from the secondary_free_list.
3957 if (!G1StressConcRegionFreeing) {
3958 append_secondary_free_list_if_not_empty_with_lock();
3959 }
3960
3961 assert(check_young_list_well_formed(), "young list should be well formed");
3962 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3963 "sanity check");
3964
3965 // Don't dynamically change the number of GC threads this early. A value of
3966 // 0 is used to indicate serial work. When parallel work is done,
3967 // it will be set.
3968
3969 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3970 IsGCActiveMark x;
3971
3972 gc_prologue(false);
3973 increment_total_collections(false /* full gc */);
3974 increment_gc_time_stamp();
3975
3976 verify_before_gc();
3977
3978 COMPILER2_PRESENT(DerivedPointerTable::clear());
3979
3980 // Please see comment in g1CollectedHeap.hpp and
3981 // G1CollectedHeap::ref_processing_init() to see how
3982 // reference processing currently works in G1.
3983
3984 // Enable discovery in the STW reference processor
3985 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3986 true /*verify_no_refs*/);
3987
3988 {
3989 // We want to temporarily turn off discovery by the
3990 // CM ref processor, if necessary, and turn it back on
3991 // on again later if we do. Using a scoped
3992 // NoRefDiscovery object will do this.
3993 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3994
3995 // Forget the current alloc region (we might even choose it to be part
3996 // of the collection set!).
3997 release_mutator_alloc_region();
3998
3999 // We should call this after we retire the mutator alloc
4000 // region(s) so that all the ALLOC / RETIRE events are generated
4001 // before the start GC event.
4002 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4003
4004 // This timing is only used by the ergonomics to handle our pause target.
4005 // It is unclear why this should not include the full pause. We will
4006 // investigate this in CR 7178365.
4007 //
4008 // Preserving the old comment here if that helps the investigation:
4009 //
4010 // The elapsed time induced by the start time below deliberately elides
4011 // the possible verification above.
4012 double sample_start_time_sec = os::elapsedTime();
4013
4014 #if YOUNG_LIST_VERBOSE
4015 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4016 _young_list->print();
4017 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4018 #endif // YOUNG_LIST_VERBOSE
4019
4020 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4021
4022 double scan_wait_start = os::elapsedTime();
4023 // We have to wait until the CM threads finish scanning the
4024 // root regions as it's the only way to ensure that all the
4025 // objects on them have been correctly scanned before we start
4026 // moving them during the GC.
4027 bool waited = _cm->root_regions()->wait_until_scan_finished();
4028 double wait_time_ms = 0.0;
4029 if (waited) {
4030 double scan_wait_end = os::elapsedTime();
4031 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4032 }
4033 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4034
4035 #if YOUNG_LIST_VERBOSE
4036 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4037 _young_list->print();
4038 #endif // YOUNG_LIST_VERBOSE
4039
4040 if (g1_policy()->during_initial_mark_pause()) {
4041 concurrent_mark()->checkpointRootsInitialPre();
4042 }
4043
4044 #if YOUNG_LIST_VERBOSE
4045 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4046 _young_list->print();
4047 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4048 #endif // YOUNG_LIST_VERBOSE
4049
4050 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4051
4052 _cm->note_start_of_gc();
4053 // We should not verify the per-thread SATB buffers given that
4054 // we have not filtered them yet (we'll do so during the
4055 // GC). We also call this after finalize_cset() to
4056 // ensure that the CSet has been finalized.
4057 _cm->verify_no_cset_oops(true /* verify_stacks */,
4058 true /* verify_enqueued_buffers */,
4059 false /* verify_thread_buffers */,
4060 true /* verify_fingers */);
4061
4062 if (_hr_printer.is_active()) {
4063 HeapRegion* hr = g1_policy()->collection_set();
4064 while (hr != NULL) {
4065 G1HRPrinter::RegionType type;
4066 if (!hr->is_young()) {
4067 type = G1HRPrinter::Old;
4068 } else if (hr->is_survivor()) {
4069 type = G1HRPrinter::Survivor;
4070 } else {
4071 type = G1HRPrinter::Eden;
4072 }
4073 _hr_printer.cset(hr);
4074 hr = hr->next_in_collection_set();
4075 }
4076 }
4077
4078 #ifdef ASSERT
4079 VerifyCSetClosure cl;
4080 collection_set_iterate(&cl);
4081 #endif // ASSERT
4082
4083 setup_surviving_young_words();
4084
4085 // Initialize the GC alloc regions.
4086 init_gc_alloc_regions(evacuation_info);
4087
4088 // Actually do the work...
4089 evacuate_collection_set(evacuation_info);
4090
4091 // We do this to mainly verify the per-thread SATB buffers
4092 // (which have been filtered by now) since we didn't verify
4093 // them earlier. No point in re-checking the stacks / enqueued
4094 // buffers given that the CSet has not changed since last time
4095 // we checked.
4096 _cm->verify_no_cset_oops(false /* verify_stacks */,
4097 false /* verify_enqueued_buffers */,
4098 true /* verify_thread_buffers */,
4099 true /* verify_fingers */);
4100
4101 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4102 g1_policy()->clear_collection_set();
4103
4104 cleanup_surviving_young_words();
4105
4106 // Start a new incremental collection set for the next pause.
4107 g1_policy()->start_incremental_cset_building();
4108
4109 // Clear the _cset_fast_test bitmap in anticipation of adding
4110 // regions to the incremental collection set for the next
4111 // evacuation pause.
4112 clear_cset_fast_test();
4113
4114 _young_list->reset_sampled_info();
4115
4116 // Don't check the whole heap at this point as the
4117 // GC alloc regions from this pause have been tagged
4118 // as survivors and moved on to the survivor list.
4119 // Survivor regions will fail the !is_young() check.
4120 assert(check_young_list_empty(false /* check_heap */),
4121 "young list should be empty");
4122
4123 #if YOUNG_LIST_VERBOSE
4124 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4125 _young_list->print();
4126 #endif // YOUNG_LIST_VERBOSE
4127
4128 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4129 _young_list->first_survivor_region(),
4130 _young_list->last_survivor_region());
4131
4132 _young_list->reset_auxilary_lists();
4133
4134 if (evacuation_failed()) {
4135 _summary_bytes_used = recalculate_used();
4136 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4137 for (uint i = 0; i < n_queues; i++) {
4138 if (_evacuation_failed_info_array[i].has_failed()) {
4139 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4140 }
4141 }
4142 } else {
4143 // The "used" of the the collection set have already been subtracted
4144 // when they were freed. Add in the bytes evacuated.
4145 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4146 }
4147
4148 if (g1_policy()->during_initial_mark_pause()) {
4149 // We have to do this before we notify the CM threads that
4150 // they can start working to make sure that all the
4151 // appropriate initialization is done on the CM object.
4152 concurrent_mark()->checkpointRootsInitialPost();
4153 set_marking_started();
4154 // Note that we don't actually trigger the CM thread at
4155 // this point. We do that later when we're sure that
4156 // the current thread has completed its logging output.
4157 }
4158
4159 allocate_dummy_regions();
4160
4161 #if YOUNG_LIST_VERBOSE
4162 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4163 _young_list->print();
4164 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4165 #endif // YOUNG_LIST_VERBOSE
4166
4167 init_mutator_alloc_region();
4168
4169 {
4170 size_t expand_bytes = g1_policy()->expansion_amount();
4171 if (expand_bytes > 0) {
4172 size_t bytes_before = capacity();
4173 // No need for an ergo verbose message here,
4174 // expansion_amount() does this when it returns a value > 0.
4175 if (!expand(expand_bytes)) {
4176 // We failed to expand the heap so let's verify that
4177 // committed/uncommitted amount match the backing store
4178 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4179 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4180 }
4181 }
4182 }
4183
4184 // We redo the verification but now wrt to the new CSet which
4185 // has just got initialized after the previous CSet was freed.
4186 _cm->verify_no_cset_oops(true /* verify_stacks */,
4187 true /* verify_enqueued_buffers */,
4188 true /* verify_thread_buffers */,
4189 true /* verify_fingers */);
4190 _cm->note_end_of_gc();
4191
4192 // This timing is only used by the ergonomics to handle our pause target.
4193 // It is unclear why this should not include the full pause. We will
4194 // investigate this in CR 7178365.
4195 double sample_end_time_sec = os::elapsedTime();
4196 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4197 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4198
4199 MemoryService::track_memory_usage();
4200
4201 // In prepare_for_verify() below we'll need to scan the deferred
4202 // update buffers to bring the RSets up-to-date if
4203 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4204 // the update buffers we'll probably need to scan cards on the
4205 // regions we just allocated to (i.e., the GC alloc
4206 // regions). However, during the last GC we called
4207 // set_saved_mark() on all the GC alloc regions, so card
4208 // scanning might skip the [saved_mark_word()...top()] area of
4209 // those regions (i.e., the area we allocated objects into
4210 // during the last GC). But it shouldn't. Given that
4211 // saved_mark_word() is conditional on whether the GC time stamp
4212 // on the region is current or not, by incrementing the GC time
4213 // stamp here we invalidate all the GC time stamps on all the
4214 // regions and saved_mark_word() will simply return top() for
4215 // all the regions. This is a nicer way of ensuring this rather
4216 // than iterating over the regions and fixing them. In fact, the
4217 // GC time stamp increment here also ensures that
4218 // saved_mark_word() will return top() between pauses, i.e.,
4219 // during concurrent refinement. So we don't need the
4220 // is_gc_active() check to decided which top to use when
4221 // scanning cards (see CR 7039627).
4222 increment_gc_time_stamp();
4223
4224 verify_after_gc();
4225
4226 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4227 ref_processor_stw()->verify_no_references_recorded();
4228
4229 // CM reference discovery will be re-enabled if necessary.
4230 }
4231
4232 // We should do this after we potentially expand the heap so
4233 // that all the COMMIT events are generated before the end GC
4234 // event, and after we retire the GC alloc regions so that all
4235 // RETIRE events are generated before the end GC event.
4236 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4237
4238 if (mark_in_progress()) {
4239 concurrent_mark()->update_g1_committed();
4240 }
4241
4242 #ifdef TRACESPINNING
4243 ParallelTaskTerminator::print_termination_counts();
4244 #endif
4245
4246 gc_epilogue(false);
4247 }
4248
4249 // Print the remainder of the GC log output.
4250 log_gc_footer(os::elapsedTime() - pause_start_sec);
4251
4252 // It is not yet to safe to tell the concurrent mark to
4253 // start as we have some optional output below. We don't want the
4254 // output from the concurrent mark thread interfering with this
4255 // logging output either.
4256
4257 _hrs.verify_optional();
4258 verify_region_sets_optional();
4259
4260 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4261 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4262
4263 print_heap_after_gc();
4264 trace_heap_after_gc(_gc_tracer_stw);
4265
4266 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4267 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4268 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4269 // before any GC notifications are raised.
4270 g1mm()->update_sizes();
4271
4272 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4273 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4274 _gc_timer_stw->register_gc_end();
4275 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4276 }
4277 // It should now be safe to tell the concurrent mark thread to start
4278 // without its logging output interfering with the logging output
4279 // that came from the pause.
4280
4281 if (should_start_conc_mark) {
4282 // CAUTION: after the doConcurrentMark() call below,
4283 // the concurrent marking thread(s) could be running
4284 // concurrently with us. Make sure that anything after
4285 // this point does not assume that we are the only GC thread
4286 // running. Note: of course, the actual marking work will
4287 // not start until the safepoint itself is released in
4288 // ConcurrentGCThread::safepoint_desynchronize().
4289 doConcurrentMark();
4290 }
4291
4292 return true;
4293 }
4294
4295 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4296 {
4297 size_t gclab_word_size;
4298 switch (purpose) {
4299 case GCAllocForSurvived:
4300 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4301 break;
4302 case GCAllocForTenured:
4303 gclab_word_size = _old_plab_stats.desired_plab_sz();
4304 break;
4305 default:
4306 assert(false, "unknown GCAllocPurpose");
4307 gclab_word_size = _old_plab_stats.desired_plab_sz();
4308 break;
4309 }
4310
4311 // Prevent humongous PLAB sizes for two reasons:
4312 // * PLABs are allocated using a similar paths as oops, but should
4313 // never be in a humongous region
4314 // * Allowing humongous PLABs needlessly churns the region free lists
4315 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4316 }
4317
4318 void G1CollectedHeap::init_mutator_alloc_region() {
4319 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4320 _mutator_alloc_region.init();
4321 }
4322
4323 void G1CollectedHeap::release_mutator_alloc_region() {
4324 _mutator_alloc_region.release();
4325 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4326 }
4327
4328 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4329 assert_at_safepoint(true /* should_be_vm_thread */);
4330
4331 _survivor_gc_alloc_region.init();
4332 _old_gc_alloc_region.init();
4333 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4334 _retained_old_gc_alloc_region = NULL;
4335
4336 // We will discard the current GC alloc region if:
4337 // a) it's in the collection set (it can happen!),
4338 // b) it's already full (no point in using it),
4339 // c) it's empty (this means that it was emptied during
4340 // a cleanup and it should be on the free list now), or
4341 // d) it's humongous (this means that it was emptied
4342 // during a cleanup and was added to the free list, but
4343 // has been subsequently used to allocate a humongous
4344 // object that may be less than the region size).
4345 if (retained_region != NULL &&
4346 !retained_region->in_collection_set() &&
4347 !(retained_region->top() == retained_region->end()) &&
4348 !retained_region->is_empty() &&
4349 !retained_region->isHumongous()) {
4350 retained_region->set_saved_mark();
4351 // The retained region was added to the old region set when it was
4352 // retired. We have to remove it now, since we don't allow regions
4353 // we allocate to in the region sets. We'll re-add it later, when
4354 // it's retired again.
4355 _old_set.remove(retained_region);
4356 bool during_im = g1_policy()->during_initial_mark_pause();
4357 retained_region->note_start_of_copying(during_im);
4358 _old_gc_alloc_region.set(retained_region);
4359 _hr_printer.reuse(retained_region);
4360 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4361 }
4362 }
4363
4364 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4365 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4366 _old_gc_alloc_region.count());
4367 _survivor_gc_alloc_region.release();
4368 // If we have an old GC alloc region to release, we'll save it in
4369 // _retained_old_gc_alloc_region. If we don't
4370 // _retained_old_gc_alloc_region will become NULL. This is what we
4371 // want either way so no reason to check explicitly for either
4372 // condition.
4373 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4374
4375 if (ResizePLAB) {
4376 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4377 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4378 }
4379 }
4380
4381 void G1CollectedHeap::abandon_gc_alloc_regions() {
4382 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4383 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4384 _retained_old_gc_alloc_region = NULL;
4385 }
4386
4387 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4388 _drain_in_progress = false;
4389 set_evac_failure_closure(cl);
4390 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4391 }
4392
4393 void G1CollectedHeap::finalize_for_evac_failure() {
4394 assert(_evac_failure_scan_stack != NULL &&
4395 _evac_failure_scan_stack->length() == 0,
4396 "Postcondition");
4397 assert(!_drain_in_progress, "Postcondition");
4398 delete _evac_failure_scan_stack;
4399 _evac_failure_scan_stack = NULL;
4400 }
4401
4402 void G1CollectedHeap::remove_self_forwarding_pointers() {
4403 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4404
4405 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4406
4407 if (G1CollectedHeap::use_parallel_gc_threads()) {
4408 set_par_threads();
4409 workers()->run_task(&rsfp_task);
4410 set_par_threads(0);
4411 } else {
4412 rsfp_task.work(0);
4413 }
4414
4415 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4416
4417 // Reset the claim values in the regions in the collection set.
4418 reset_cset_heap_region_claim_values();
4419
4420 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4421
4422 // Now restore saved marks, if any.
4423 assert(_objs_with_preserved_marks.size() ==
4424 _preserved_marks_of_objs.size(), "Both or none.");
4425 while (!_objs_with_preserved_marks.is_empty()) {
4426 oop obj = _objs_with_preserved_marks.pop();
4427 markOop m = _preserved_marks_of_objs.pop();
4428 obj->set_mark(m);
4429 }
4430 _objs_with_preserved_marks.clear(true);
4431 _preserved_marks_of_objs.clear(true);
4432 }
4433
4434 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4435 _evac_failure_scan_stack->push(obj);
4436 }
4437
4438 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4439 assert(_evac_failure_scan_stack != NULL, "precondition");
4440
4441 while (_evac_failure_scan_stack->length() > 0) {
4442 oop obj = _evac_failure_scan_stack->pop();
4443 _evac_failure_closure->set_region(heap_region_containing(obj));
4444 obj->oop_iterate_backwards(_evac_failure_closure);
4445 }
4446 }
4447
4448 oop
4449 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4450 oop old) {
4451 assert(obj_in_cs(old),
4452 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4453 (HeapWord*) old));
4454 markOop m = old->mark();
4455 oop forward_ptr = old->forward_to_atomic(old);
4456 if (forward_ptr == NULL) {
4457 // Forward-to-self succeeded.
4458 assert(_par_scan_state != NULL, "par scan state");
4459 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4460 uint queue_num = _par_scan_state->queue_num();
4461
4462 _evacuation_failed = true;
4463 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4464 if (_evac_failure_closure != cl) {
4465 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4466 assert(!_drain_in_progress,
4467 "Should only be true while someone holds the lock.");
4468 // Set the global evac-failure closure to the current thread's.
4469 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4470 set_evac_failure_closure(cl);
4471 // Now do the common part.
4472 handle_evacuation_failure_common(old, m);
4473 // Reset to NULL.
4474 set_evac_failure_closure(NULL);
4475 } else {
4476 // The lock is already held, and this is recursive.
4477 assert(_drain_in_progress, "This should only be the recursive case.");
4478 handle_evacuation_failure_common(old, m);
4479 }
4480 return old;
4481 } else {
4482 // Forward-to-self failed. Either someone else managed to allocate
4483 // space for this object (old != forward_ptr) or they beat us in
4484 // self-forwarding it (old == forward_ptr).
4485 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4486 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4487 "should not be in the CSet",
4488 (HeapWord*) old, (HeapWord*) forward_ptr));
4489 return forward_ptr;
4490 }
4491 }
4492
4493 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4494 preserve_mark_if_necessary(old, m);
4495
4496 HeapRegion* r = heap_region_containing(old);
4497 if (!r->evacuation_failed()) {
4498 r->set_evacuation_failed(true);
4499 _hr_printer.evac_failure(r);
4500 }
4501
4502 push_on_evac_failure_scan_stack(old);
4503
4504 if (!_drain_in_progress) {
4505 // prevent recursion in copy_to_survivor_space()
4506 _drain_in_progress = true;
4507 drain_evac_failure_scan_stack();
4508 _drain_in_progress = false;
4509 }
4510 }
4511
4512 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4513 assert(evacuation_failed(), "Oversaving!");
4514 // We want to call the "for_promotion_failure" version only in the
4515 // case of a promotion failure.
4516 if (m->must_be_preserved_for_promotion_failure(obj)) {
4517 _objs_with_preserved_marks.push(obj);
4518 _preserved_marks_of_objs.push(m);
4519 }
4520 }
4521
4522 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4523 size_t word_size) {
4524 if (purpose == GCAllocForSurvived) {
4525 HeapWord* result = survivor_attempt_allocation(word_size);
4526 if (result != NULL) {
4527 return result;
4528 } else {
4529 // Let's try to allocate in the old gen in case we can fit the
4530 // object there.
4531 return old_attempt_allocation(word_size);
4532 }
4533 } else {
4534 assert(purpose == GCAllocForTenured, "sanity");
4535 HeapWord* result = old_attempt_allocation(word_size);
4536 if (result != NULL) {
4537 return result;
4538 } else {
4539 // Let's try to allocate in the survivors in case we can fit the
4540 // object there.
4541 return survivor_attempt_allocation(word_size);
4542 }
4543 }
4544
4545 ShouldNotReachHere();
4546 // Trying to keep some compilers happy.
4547 return NULL;
4548 }
4549
4550 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4551 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4552
4553 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4554 : _g1h(g1h),
4555 _refs(g1h->task_queue(queue_num)),
4556 _dcq(&g1h->dirty_card_queue_set()),
4557 _ct_bs(g1h->g1_barrier_set()),
4558 _g1_rem(g1h->g1_rem_set()),
4559 _hash_seed(17), _queue_num(queue_num),
4560 _term_attempts(0),
4561 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4562 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4563 _age_table(false), _scanner(g1h, this, rp),
4564 _strong_roots_time(0), _term_time(0),
4565 _alloc_buffer_waste(0), _undo_waste(0) {
4566 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4567 // we "sacrifice" entry 0 to keep track of surviving bytes for
4568 // non-young regions (where the age is -1)
4569 // We also add a few elements at the beginning and at the end in
4570 // an attempt to eliminate cache contention
4571 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4572 uint array_length = PADDING_ELEM_NUM +
4573 real_length +
4574 PADDING_ELEM_NUM;
4575 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4576 if (_surviving_young_words_base == NULL)
4577 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4578 "Not enough space for young surv histo.");
4579 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4580 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4581
4582 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4583 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4584
4585 _start = os::elapsedTime();
4586 }
4587
4588 void
4589 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4590 {
4591 st->print_raw_cr("GC Termination Stats");
4592 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4593 " ------waste (KiB)------");
4594 st->print_raw_cr("thr ms ms % ms % attempts"
4595 " total alloc undo");
4596 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4597 " ------- ------- -------");
4598 }
4599
4600 void
4601 G1ParScanThreadState::print_termination_stats(int i,
4602 outputStream* const st) const
4603 {
4604 const double elapsed_ms = elapsed_time() * 1000.0;
4605 const double s_roots_ms = strong_roots_time() * 1000.0;
4606 const double term_ms = term_time() * 1000.0;
4607 st->print_cr("%3d %9.2f %9.2f %6.2f "
4608 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4609 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4610 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4611 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4612 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4613 alloc_buffer_waste() * HeapWordSize / K,
4614 undo_waste() * HeapWordSize / K);
4615 }
4616
4617 #ifdef ASSERT
4618 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4619 assert(ref != NULL, "invariant");
4620 assert(UseCompressedOops, "sanity");
4621 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4622 oop p = oopDesc::load_decode_heap_oop(ref);
4623 assert(_g1h->is_in_g1_reserved(p),
4624 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4625 return true;
4626 }
4627
4628 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4629 assert(ref != NULL, "invariant");
4630 if (has_partial_array_mask(ref)) {
4631 // Must be in the collection set--it's already been copied.
4632 oop p = clear_partial_array_mask(ref);
4633 assert(_g1h->obj_in_cs(p),
4634 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4635 } else {
4636 oop p = oopDesc::load_decode_heap_oop(ref);
4637 assert(_g1h->is_in_g1_reserved(p),
4638 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4639 }
4640 return true;
4641 }
4642
4643 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4644 if (ref.is_narrow()) {
4645 return verify_ref((narrowOop*) ref);
4646 } else {
4647 return verify_ref((oop*) ref);
4648 }
4649 }
4650 #endif // ASSERT
4651
4652 void G1ParScanThreadState::trim_queue() {
4653 assert(_evac_cl != NULL, "not set");
4654 assert(_evac_failure_cl != NULL, "not set");
4655 assert(_partial_scan_cl != NULL, "not set");
4656
4657 StarTask ref;
4658 do {
4659 // Drain the overflow stack first, so other threads can steal.
4660 while (refs()->pop_overflow(ref)) {
4661 deal_with_reference(ref);
4662 }
4663
4664 while (refs()->pop_local(ref)) {
4665 deal_with_reference(ref);
4666 }
4667 } while (!refs()->is_empty());
4668 }
4669
4670 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4671 G1ParScanThreadState* par_scan_state) :
4672 _g1(g1), _par_scan_state(par_scan_state),
4673 _worker_id(par_scan_state->queue_num()) { }
4674
4675 void G1ParCopyHelper::mark_object(oop obj) {
4676 #ifdef ASSERT
4677 HeapRegion* hr = _g1->heap_region_containing(obj);
4678 assert(hr != NULL, "sanity");
4679 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4680 #endif // ASSERT
4681
4682 // We know that the object is not moving so it's safe to read its size.
4683 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4684 }
4685
4686 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4687 #ifdef ASSERT
4688 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4689 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4690 assert(from_obj != to_obj, "should not be self-forwarded");
4691
4692 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4693 assert(from_hr != NULL, "sanity");
4694 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4695
4696 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4697 assert(to_hr != NULL, "sanity");
4698 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4699 #endif // ASSERT
4700
4701 // The object might be in the process of being copied by another
4702 // worker so we cannot trust that its to-space image is
4703 // well-formed. So we have to read its size from its from-space
4704 // image which we know should not be changing.
4705 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4706 }
4707
4708 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4709 size_t word_sz = old->size();
4710 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4711 // +1 to make the -1 indexes valid...
4712 int young_index = from_region->young_index_in_cset()+1;
4713 assert( (from_region->is_young() && young_index > 0) ||
4714 (!from_region->is_young() && young_index == 0), "invariant" );
4715 G1CollectorPolicy* g1p = _g1h->g1_policy();
4716 markOop m = old->mark();
4717 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4718 : m->age();
4719 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4720 word_sz);
4721 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4722 #ifndef PRODUCT
4723 // Should this evacuation fail?
4724 if (_g1h->evacuation_should_fail()) {
4725 if (obj_ptr != NULL) {
4726 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4727 obj_ptr = NULL;
4728 }
4729 }
4730 #endif // !PRODUCT
4731
4732 if (obj_ptr == NULL) {
4733 // This will either forward-to-self, or detect that someone else has
4734 // installed a forwarding pointer.
4735 return _g1h->handle_evacuation_failure_par(this, old);
4736 }
4737
4738 oop obj = oop(obj_ptr);
4739
4740 // We're going to allocate linearly, so might as well prefetch ahead.
4741 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4742
4743 oop forward_ptr = old->forward_to_atomic(obj);
4744 if (forward_ptr == NULL) {
4745 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4746
4747 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4748 // we actually allocated from and update alloc_purpose accordingly
4749 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4750 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4751
4752 if (g1p->track_object_age(alloc_purpose)) {
4753 // We could simply do obj->incr_age(). However, this causes a
4754 // performance issue. obj->incr_age() will first check whether
4755 // the object has a displaced mark by checking its mark word;
4756 // getting the mark word from the new location of the object
4757 // stalls. So, given that we already have the mark word and we
4758 // are about to install it anyway, it's better to increase the
4759 // age on the mark word, when the object does not have a
4760 // displaced mark word. We're not expecting many objects to have
4761 // a displaced marked word, so that case is not optimized
4762 // further (it could be...) and we simply call obj->incr_age().
4763
4764 if (m->has_displaced_mark_helper()) {
4765 // in this case, we have to install the mark word first,
4766 // otherwise obj looks to be forwarded (the old mark word,
4767 // which contains the forward pointer, was copied)
4768 obj->set_mark(m);
4769 obj->incr_age();
4770 } else {
4771 m = m->incr_age();
4772 obj->set_mark(m);
4773 }
4774 age_table()->add(obj, word_sz);
4775 } else {
4776 obj->set_mark(m);
4777 }
4778
4779 size_t* surv_young_words = surviving_young_words();
4780 surv_young_words[young_index] += word_sz;
4781
4782 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4783 // We keep track of the next start index in the length field of
4784 // the to-space object. The actual length can be found in the
4785 // length field of the from-space object.
4786 arrayOop(obj)->set_length(0);
4787 oop* old_p = set_partial_array_mask(old);
4788 push_on_queue(old_p);
4789 } else {
4790 // No point in using the slower heap_region_containing() method,
4791 // given that we know obj is in the heap.
4792 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4793 obj->oop_iterate_backwards(&_scanner);
4794 }
4795 } else {
4796 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4797 obj = forward_ptr;
4798 }
4799 return obj;
4800 }
4801
4802 template <class T>
4803 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4804 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4805 _scanned_klass->record_modified_oops();
4806 }
4807 }
4808
4809 template <G1Barrier barrier, bool do_mark_object>
4810 template <class T>
4811 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4812 T heap_oop = oopDesc::load_heap_oop(p);
4813
4814 if (oopDesc::is_null(heap_oop)) {
4815 return;
4816 }
4817
4818 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4819
4820 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4821
4822 if (_g1->in_cset_fast_test(obj)) {
4823 oop forwardee;
4824 if (obj->is_forwarded()) {
4825 forwardee = obj->forwardee();
4826 } else {
4827 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4828 }
4829 assert(forwardee != NULL, "forwardee should not be NULL");
4830 oopDesc::encode_store_heap_oop(p, forwardee);
4831 if (do_mark_object && forwardee != obj) {
4832 // If the object is self-forwarded we don't need to explicitly
4833 // mark it, the evacuation failure protocol will do so.
4834 mark_forwarded_object(obj, forwardee);
4835 }
4836
4837 if (barrier == G1BarrierKlass) {
4838 do_klass_barrier(p, forwardee);
4839 }
4840 } else {
4841 // The object is not in collection set. If we're a root scanning
4842 // closure during an initial mark pause (i.e. do_mark_object will
4843 // be true) then attempt to mark the object.
4844 if (do_mark_object) {
4845 mark_object(obj);
4846 }
4847 }
4848
4849 if (barrier == G1BarrierEvac) {
4850 _par_scan_state->update_rs(_from, p, _worker_id);
4851 }
4852 }
4853
4854 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4855 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4856
4857 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4858 assert(has_partial_array_mask(p), "invariant");
4859 oop from_obj = clear_partial_array_mask(p);
4860
4861 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4862 assert(from_obj->is_objArray(), "must be obj array");
4863 objArrayOop from_obj_array = objArrayOop(from_obj);
4864 // The from-space object contains the real length.
4865 int length = from_obj_array->length();
4866
4867 assert(from_obj->is_forwarded(), "must be forwarded");
4868 oop to_obj = from_obj->forwardee();
4869 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4870 objArrayOop to_obj_array = objArrayOop(to_obj);
4871 // We keep track of the next start index in the length field of the
4872 // to-space object.
4873 int next_index = to_obj_array->length();
4874 assert(0 <= next_index && next_index < length,
4875 err_msg("invariant, next index: %d, length: %d", next_index, length));
4876
4877 int start = next_index;
4878 int end = length;
4879 int remainder = end - start;
4880 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4881 if (remainder > 2 * ParGCArrayScanChunk) {
4882 end = start + ParGCArrayScanChunk;
4883 to_obj_array->set_length(end);
4884 // Push the remainder before we process the range in case another
4885 // worker has run out of things to do and can steal it.
4886 oop* from_obj_p = set_partial_array_mask(from_obj);
4887 _par_scan_state->push_on_queue(from_obj_p);
4888 } else {
4889 assert(length == end, "sanity");
4890 // We'll process the final range for this object. Restore the length
4891 // so that the heap remains parsable in case of evacuation failure.
4892 to_obj_array->set_length(end);
4893 }
4894 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4895 // Process indexes [start,end). It will also process the header
4896 // along with the first chunk (i.e., the chunk with start == 0).
4897 // Note that at this point the length field of to_obj_array is not
4898 // correct given that we are using it to keep track of the next
4899 // start index. oop_iterate_range() (thankfully!) ignores the length
4900 // field and only relies on the start / end parameters. It does
4901 // however return the size of the object which will be incorrect. So
4902 // we have to ignore it even if we wanted to use it.
4903 to_obj_array->oop_iterate_range(&_scanner, start, end);
4904 }
4905
4906 class G1ParEvacuateFollowersClosure : public VoidClosure {
4907 protected:
4908 G1CollectedHeap* _g1h;
4909 G1ParScanThreadState* _par_scan_state;
4910 RefToScanQueueSet* _queues;
4911 ParallelTaskTerminator* _terminator;
4912
4913 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4914 RefToScanQueueSet* queues() { return _queues; }
4915 ParallelTaskTerminator* terminator() { return _terminator; }
4916
4917 public:
4918 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4919 G1ParScanThreadState* par_scan_state,
4920 RefToScanQueueSet* queues,
4921 ParallelTaskTerminator* terminator)
4922 : _g1h(g1h), _par_scan_state(par_scan_state),
4923 _queues(queues), _terminator(terminator) {}
4924
4925 void do_void();
4926
4927 private:
4928 inline bool offer_termination();
4929 };
4930
4931 bool G1ParEvacuateFollowersClosure::offer_termination() {
4932 G1ParScanThreadState* const pss = par_scan_state();
4933 pss->start_term_time();
4934 const bool res = terminator()->offer_termination();
4935 pss->end_term_time();
4936 return res;
4937 }
4938
4939 void G1ParEvacuateFollowersClosure::do_void() {
4940 StarTask stolen_task;
4941 G1ParScanThreadState* const pss = par_scan_state();
4942 pss->trim_queue();
4943
4944 do {
4945 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4946 assert(pss->verify_task(stolen_task), "sanity");
4947 if (stolen_task.is_narrow()) {
4948 pss->deal_with_reference((narrowOop*) stolen_task);
4949 } else {
4950 pss->deal_with_reference((oop*) stolen_task);
4951 }
4952
4953 // We've just processed a reference and we might have made
4954 // available new entries on the queues. So we have to make sure
4955 // we drain the queues as necessary.
4956 pss->trim_queue();
4957 }
4958 } while (!offer_termination());
4959
4960 pss->retire_alloc_buffers();
4961 }
4962
4963 class G1KlassScanClosure : public KlassClosure {
4964 G1ParCopyHelper* _closure;
4965 bool _process_only_dirty;
4966 int _count;
4967 public:
4968 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4969 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4970 void do_klass(Klass* klass) {
4971 // If the klass has not been dirtied we know that there's
4972 // no references into the young gen and we can skip it.
4973 if (!_process_only_dirty || klass->has_modified_oops()) {
4974 // Clean the klass since we're going to scavenge all the metadata.
4975 klass->clear_modified_oops();
4976
4977 // Tell the closure that this klass is the Klass to scavenge
4978 // and is the one to dirty if oops are left pointing into the young gen.
4979 _closure->set_scanned_klass(klass);
4980
4981 klass->oops_do(_closure);
4982
4983 _closure->set_scanned_klass(NULL);
4984 }
4985 _count++;
4986 }
4987 };
4988
4989 class G1ParTask : public AbstractGangTask {
4990 protected:
4991 G1CollectedHeap* _g1h;
4992 RefToScanQueueSet *_queues;
4993 ParallelTaskTerminator _terminator;
4994 uint _n_workers;
4995
4996 Mutex _stats_lock;
4997 Mutex* stats_lock() { return &_stats_lock; }
4998
4999 size_t getNCards() {
5000 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5001 / G1BlockOffsetSharedArray::N_bytes;
5002 }
5003
5004 public:
5005 G1ParTask(G1CollectedHeap* g1h,
5006 RefToScanQueueSet *task_queues)
5007 : AbstractGangTask("G1 collection"),
5008 _g1h(g1h),
5009 _queues(task_queues),
5010 _terminator(0, _queues),
5011 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
5012 {}
5013
5014 RefToScanQueueSet* queues() { return _queues; }
5015
5016 RefToScanQueue *work_queue(int i) {
5017 return queues()->queue(i);
5018 }
5019
5020 ParallelTaskTerminator* terminator() { return &_terminator; }
5021
5022 virtual void set_for_termination(int active_workers) {
5023 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5024 // in the young space (_par_seq_tasks) in the G1 heap
5025 // for SequentialSubTasksDone.
5026 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5027 // both of which need setting by set_n_termination().
5028 _g1h->SharedHeap::set_n_termination(active_workers);
5029 _g1h->set_n_termination(active_workers);
5030 terminator()->reset_for_reuse(active_workers);
5031 _n_workers = active_workers;
5032 }
5033
5034 void work(uint worker_id) {
5035 if (worker_id >= _n_workers) return; // no work needed this round
5036
5037 double start_time_ms = os::elapsedTime() * 1000.0;
5038 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5039
5040 {
5041 ResourceMark rm;
5042 HandleMark hm;
5043
5044 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5045
5046 G1ParScanThreadState pss(_g1h, worker_id, rp);
5047 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5048 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5049 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5050
5051 pss.set_evac_closure(&scan_evac_cl);
5052 pss.set_evac_failure_closure(&evac_failure_cl);
5053 pss.set_partial_scan_closure(&partial_scan_cl);
5054
5055 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5056 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5057
5058 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5059 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5060
5061 bool only_young = _g1h->g1_policy()->gcs_are_young();
5062 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5063 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5064
5065 OopClosure* scan_root_cl = &only_scan_root_cl;
5066 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5067
5068 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5069 // We also need to mark copied objects.
5070 scan_root_cl = &scan_mark_root_cl;
5071 scan_klasses_cl = &scan_mark_klasses_cl_s;
5072 }
5073
5074 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5075
5076 // Don't scan the scavengable methods in the code cache as part
5077 // of strong root scanning. The code roots that point into a
5078 // region in the collection set are scanned when we scan the
5079 // region's RSet.
5080 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5081
5082 pss.start_strong_roots();
5083 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5084 SharedHeap::ScanningOption(so),
5085 scan_root_cl,
5086 &push_heap_rs_cl,
5087 scan_klasses_cl,
5088 worker_id);
5089 pss.end_strong_roots();
5090
5091 {
5092 double start = os::elapsedTime();
5093 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5094 evac.do_void();
5095 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5096 double term_ms = pss.term_time()*1000.0;
5097 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5098 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5099 }
5100 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5101 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5102
5103 if (ParallelGCVerbose) {
5104 MutexLocker x(stats_lock());
5105 pss.print_termination_stats(worker_id);
5106 }
5107
5108 assert(pss.refs()->is_empty(), "should be empty");
5109
5110 // Close the inner scope so that the ResourceMark and HandleMark
5111 // destructors are executed here and are included as part of the
5112 // "GC Worker Time".
5113 }
5114
5115 double end_time_ms = os::elapsedTime() * 1000.0;
5116 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5117 }
5118 };
5119
5120 // *** Common G1 Evacuation Stuff
5121
5122 // This method is run in a GC worker.
5123
5124 void
5125 G1CollectedHeap::
5126 g1_process_strong_roots(bool is_scavenging,
5127 ScanningOption so,
5128 OopClosure* scan_non_heap_roots,
5129 OopsInHeapRegionClosure* scan_rs,
5130 G1KlassScanClosure* scan_klasses,
5131 int worker_i) {
5132
5133 // First scan the strong roots
5134 double ext_roots_start = os::elapsedTime();
5135 double closure_app_time_sec = 0.0;
5136
5137 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5138
5139 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5140 // Walk the code cache/strong code roots w/o buffering, because StarTask
5141 // cannot handle unaligned oop locations.
5142 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5143
5144 process_strong_roots(false, // no scoping; this is parallel code
5145 is_scavenging, so,
5146 &buf_scan_non_heap_roots,
5147 &eager_scan_code_roots,
5148 scan_klasses
5149 );
5150
5151 // Now the CM ref_processor roots.
5152 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5153 // We need to treat the discovered reference lists of the
5154 // concurrent mark ref processor as roots and keep entries
5155 // (which are added by the marking threads) on them live
5156 // until they can be processed at the end of marking.
5157 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5158 }
5159
5160 // Finish up any enqueued closure apps (attributed as object copy time).
5161 buf_scan_non_heap_roots.done();
5162
5163 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5164
5165 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5166
5167 double ext_root_time_ms =
5168 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5169
5170 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5171
5172 // During conc marking we have to filter the per-thread SATB buffers
5173 // to make sure we remove any oops into the CSet (which will show up
5174 // as implicitly live).
5175 double satb_filtering_ms = 0.0;
5176 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5177 if (mark_in_progress()) {
5178 double satb_filter_start = os::elapsedTime();
5179
5180 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5181
5182 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5183 }
5184 }
5185 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5186
5187 // If this is an initial mark pause, and we're not scanning
5188 // the entire code cache, we need to mark the oops in the
5189 // strong code root lists for the regions that are not in
5190 // the collection set.
5191 // Note all threads participate in this set of root tasks.
5192 double mark_strong_code_roots_ms = 0.0;
5193 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5194 double mark_strong_roots_start = os::elapsedTime();
5195 mark_strong_code_roots(worker_i);
5196 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5197 }
5198 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5199
5200 // Now scan the complement of the collection set.
5201 if (scan_rs != NULL) {
5202 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5203 }
5204 _process_strong_tasks->all_tasks_completed();
5205 }
5206
5207 void
5208 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5209 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5210 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5211 }
5212
5213 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5214 private:
5215 BoolObjectClosure* _is_alive;
5216 int _initial_string_table_size;
5217 int _initial_symbol_table_size;
5218
5219 bool _process_strings;
5220 int _strings_processed;
5221 int _strings_removed;
5222
5223 bool _process_symbols;
5224 int _symbols_processed;
5225 int _symbols_removed;
5226
5227 bool _do_in_parallel;
5228 public:
5229 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5230 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5231 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5232 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5233 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5234
5235 _initial_string_table_size = StringTable::the_table()->table_size();
5236 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5237 if (process_strings) {
5238 StringTable::clear_parallel_claimed_index();
5239 }
5240 if (process_symbols) {
5241 SymbolTable::clear_parallel_claimed_index();
5242 }
5243 }
5244
5245 ~G1StringSymbolTableUnlinkTask() {
5246 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5247 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5248 StringTable::parallel_claimed_index(), _initial_string_table_size));
5249 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5250 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5251 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5252 }
5253
5254 void work(uint worker_id) {
5255 if (_do_in_parallel) {
5256 int strings_processed = 0;
5257 int strings_removed = 0;
5258 int symbols_processed = 0;
5259 int symbols_removed = 0;
5260 if (_process_strings) {
5261 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5262 Atomic::add(strings_processed, &_strings_processed);
5263 Atomic::add(strings_removed, &_strings_removed);
5264 }
5265 if (_process_symbols) {
5266 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5267 Atomic::add(symbols_processed, &_symbols_processed);
5268 Atomic::add(symbols_removed, &_symbols_removed);
5269 }
5270 } else {
5271 if (_process_strings) {
5272 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5273 }
5274 if (_process_symbols) {
5275 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5276 }
5277 }
5278 }
5279
5280 size_t strings_processed() const { return (size_t)_strings_processed; }
5281 size_t strings_removed() const { return (size_t)_strings_removed; }
5282
5283 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5284 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5285 };
5286
5287 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5288 bool process_strings, bool process_symbols) {
5289 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5290 _g1h->workers()->active_workers() : 1);
5291
5292 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5293 if (G1CollectedHeap::use_parallel_gc_threads()) {
5294 set_par_threads(n_workers);
5295 workers()->run_task(&g1_unlink_task);
5296 set_par_threads(0);
5297 } else {
5298 g1_unlink_task.work(0);
5299 }
5300 if (G1TraceStringSymbolTableScrubbing) {
5301 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5302 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5303 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5304 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5305 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5306 }
5307 }
5308
5309 // Weak Reference Processing support
5310
5311 // An always "is_alive" closure that is used to preserve referents.
5312 // If the object is non-null then it's alive. Used in the preservation
5313 // of referent objects that are pointed to by reference objects
5314 // discovered by the CM ref processor.
5315 class G1AlwaysAliveClosure: public BoolObjectClosure {
5316 G1CollectedHeap* _g1;
5317 public:
5318 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5319 bool do_object_b(oop p) {
5320 if (p != NULL) {
5321 return true;
5322 }
5323 return false;
5324 }
5325 };
5326
5327 bool G1STWIsAliveClosure::do_object_b(oop p) {
5328 // An object is reachable if it is outside the collection set,
5329 // or is inside and copied.
5330 return !_g1->obj_in_cs(p) || p->is_forwarded();
5331 }
5332
5333 // Non Copying Keep Alive closure
5334 class G1KeepAliveClosure: public OopClosure {
5335 G1CollectedHeap* _g1;
5336 public:
5337 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5338 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5339 void do_oop( oop* p) {
5340 oop obj = *p;
5341
5342 if (_g1->obj_in_cs(obj)) {
5343 assert( obj->is_forwarded(), "invariant" );
5344 *p = obj->forwardee();
5345 }
5346 }
5347 };
5348
5349 // Copying Keep Alive closure - can be called from both
5350 // serial and parallel code as long as different worker
5351 // threads utilize different G1ParScanThreadState instances
5352 // and different queues.
5353
5354 class G1CopyingKeepAliveClosure: public OopClosure {
5355 G1CollectedHeap* _g1h;
5356 OopClosure* _copy_non_heap_obj_cl;
5357 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5358 G1ParScanThreadState* _par_scan_state;
5359
5360 public:
5361 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5362 OopClosure* non_heap_obj_cl,
5363 OopsInHeapRegionClosure* metadata_obj_cl,
5364 G1ParScanThreadState* pss):
5365 _g1h(g1h),
5366 _copy_non_heap_obj_cl(non_heap_obj_cl),
5367 _copy_metadata_obj_cl(metadata_obj_cl),
5368 _par_scan_state(pss)
5369 {}
5370
5371 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5372 virtual void do_oop( oop* p) { do_oop_work(p); }
5373
5374 template <class T> void do_oop_work(T* p) {
5375 oop obj = oopDesc::load_decode_heap_oop(p);
5376
5377 if (_g1h->obj_in_cs(obj)) {
5378 // If the referent object has been forwarded (either copied
5379 // to a new location or to itself in the event of an
5380 // evacuation failure) then we need to update the reference
5381 // field and, if both reference and referent are in the G1
5382 // heap, update the RSet for the referent.
5383 //
5384 // If the referent has not been forwarded then we have to keep
5385 // it alive by policy. Therefore we have copy the referent.
5386 //
5387 // If the reference field is in the G1 heap then we can push
5388 // on the PSS queue. When the queue is drained (after each
5389 // phase of reference processing) the object and it's followers
5390 // will be copied, the reference field set to point to the
5391 // new location, and the RSet updated. Otherwise we need to
5392 // use the the non-heap or metadata closures directly to copy
5393 // the referent object and update the pointer, while avoiding
5394 // updating the RSet.
5395
5396 if (_g1h->is_in_g1_reserved(p)) {
5397 _par_scan_state->push_on_queue(p);
5398 } else {
5399 assert(!ClassLoaderDataGraph::contains((address)p),
5400 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5401 PTR_FORMAT, p));
5402 _copy_non_heap_obj_cl->do_oop(p);
5403 }
5404 }
5405 }
5406 };
5407
5408 // Serial drain queue closure. Called as the 'complete_gc'
5409 // closure for each discovered list in some of the
5410 // reference processing phases.
5411
5412 class G1STWDrainQueueClosure: public VoidClosure {
5413 protected:
5414 G1CollectedHeap* _g1h;
5415 G1ParScanThreadState* _par_scan_state;
5416
5417 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5418
5419 public:
5420 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5421 _g1h(g1h),
5422 _par_scan_state(pss)
5423 { }
5424
5425 void do_void() {
5426 G1ParScanThreadState* const pss = par_scan_state();
5427 pss->trim_queue();
5428 }
5429 };
5430
5431 // Parallel Reference Processing closures
5432
5433 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5434 // processing during G1 evacuation pauses.
5435
5436 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5437 private:
5438 G1CollectedHeap* _g1h;
5439 RefToScanQueueSet* _queues;
5440 FlexibleWorkGang* _workers;
5441 int _active_workers;
5442
5443 public:
5444 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5445 FlexibleWorkGang* workers,
5446 RefToScanQueueSet *task_queues,
5447 int n_workers) :
5448 _g1h(g1h),
5449 _queues(task_queues),
5450 _workers(workers),
5451 _active_workers(n_workers)
5452 {
5453 assert(n_workers > 0, "shouldn't call this otherwise");
5454 }
5455
5456 // Executes the given task using concurrent marking worker threads.
5457 virtual void execute(ProcessTask& task);
5458 virtual void execute(EnqueueTask& task);
5459 };
5460
5461 // Gang task for possibly parallel reference processing
5462
5463 class G1STWRefProcTaskProxy: public AbstractGangTask {
5464 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5465 ProcessTask& _proc_task;
5466 G1CollectedHeap* _g1h;
5467 RefToScanQueueSet *_task_queues;
5468 ParallelTaskTerminator* _terminator;
5469
5470 public:
5471 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5472 G1CollectedHeap* g1h,
5473 RefToScanQueueSet *task_queues,
5474 ParallelTaskTerminator* terminator) :
5475 AbstractGangTask("Process reference objects in parallel"),
5476 _proc_task(proc_task),
5477 _g1h(g1h),
5478 _task_queues(task_queues),
5479 _terminator(terminator)
5480 {}
5481
5482 virtual void work(uint worker_id) {
5483 // The reference processing task executed by a single worker.
5484 ResourceMark rm;
5485 HandleMark hm;
5486
5487 G1STWIsAliveClosure is_alive(_g1h);
5488
5489 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5490
5491 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5492 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5493 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5494
5495 pss.set_evac_closure(&scan_evac_cl);
5496 pss.set_evac_failure_closure(&evac_failure_cl);
5497 pss.set_partial_scan_closure(&partial_scan_cl);
5498
5499 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5500 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5501
5502 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5503 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5504
5505 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5506 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5507
5508 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5509 // We also need to mark copied objects.
5510 copy_non_heap_cl = ©_mark_non_heap_cl;
5511 copy_metadata_cl = ©_mark_metadata_cl;
5512 }
5513
5514 // Keep alive closure.
5515 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5516
5517 // Complete GC closure
5518 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5519
5520 // Call the reference processing task's work routine.
5521 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5522
5523 // Note we cannot assert that the refs array is empty here as not all
5524 // of the processing tasks (specifically phase2 - pp2_work) execute
5525 // the complete_gc closure (which ordinarily would drain the queue) so
5526 // the queue may not be empty.
5527 }
5528 };
5529
5530 // Driver routine for parallel reference processing.
5531 // Creates an instance of the ref processing gang
5532 // task and has the worker threads execute it.
5533 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5534 assert(_workers != NULL, "Need parallel worker threads.");
5535
5536 ParallelTaskTerminator terminator(_active_workers, _queues);
5537 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5538
5539 _g1h->set_par_threads(_active_workers);
5540 _workers->run_task(&proc_task_proxy);
5541 _g1h->set_par_threads(0);
5542 }
5543
5544 // Gang task for parallel reference enqueueing.
5545
5546 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5547 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5548 EnqueueTask& _enq_task;
5549
5550 public:
5551 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5552 AbstractGangTask("Enqueue reference objects in parallel"),
5553 _enq_task(enq_task)
5554 { }
5555
5556 virtual void work(uint worker_id) {
5557 _enq_task.work(worker_id);
5558 }
5559 };
5560
5561 // Driver routine for parallel reference enqueueing.
5562 // Creates an instance of the ref enqueueing gang
5563 // task and has the worker threads execute it.
5564
5565 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5566 assert(_workers != NULL, "Need parallel worker threads.");
5567
5568 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5569
5570 _g1h->set_par_threads(_active_workers);
5571 _workers->run_task(&enq_task_proxy);
5572 _g1h->set_par_threads(0);
5573 }
5574
5575 // End of weak reference support closures
5576
5577 // Abstract task used to preserve (i.e. copy) any referent objects
5578 // that are in the collection set and are pointed to by reference
5579 // objects discovered by the CM ref processor.
5580
5581 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5582 protected:
5583 G1CollectedHeap* _g1h;
5584 RefToScanQueueSet *_queues;
5585 ParallelTaskTerminator _terminator;
5586 uint _n_workers;
5587
5588 public:
5589 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5590 AbstractGangTask("ParPreserveCMReferents"),
5591 _g1h(g1h),
5592 _queues(task_queues),
5593 _terminator(workers, _queues),
5594 _n_workers(workers)
5595 { }
5596
5597 void work(uint worker_id) {
5598 ResourceMark rm;
5599 HandleMark hm;
5600
5601 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5602 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5603 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5604 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5605
5606 pss.set_evac_closure(&scan_evac_cl);
5607 pss.set_evac_failure_closure(&evac_failure_cl);
5608 pss.set_partial_scan_closure(&partial_scan_cl);
5609
5610 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5611
5612
5613 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5614 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5615
5616 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5617 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5618
5619 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5620 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5621
5622 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5623 // We also need to mark copied objects.
5624 copy_non_heap_cl = ©_mark_non_heap_cl;
5625 copy_metadata_cl = ©_mark_metadata_cl;
5626 }
5627
5628 // Is alive closure
5629 G1AlwaysAliveClosure always_alive(_g1h);
5630
5631 // Copying keep alive closure. Applied to referent objects that need
5632 // to be copied.
5633 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5634
5635 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5636
5637 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5638 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5639
5640 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5641 // So this must be true - but assert just in case someone decides to
5642 // change the worker ids.
5643 assert(0 <= worker_id && worker_id < limit, "sanity");
5644 assert(!rp->discovery_is_atomic(), "check this code");
5645
5646 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5647 for (uint idx = worker_id; idx < limit; idx += stride) {
5648 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5649
5650 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5651 while (iter.has_next()) {
5652 // Since discovery is not atomic for the CM ref processor, we
5653 // can see some null referent objects.
5654 iter.load_ptrs(DEBUG_ONLY(true));
5655 oop ref = iter.obj();
5656
5657 // This will filter nulls.
5658 if (iter.is_referent_alive()) {
5659 iter.make_referent_alive();
5660 }
5661 iter.move_to_next();
5662 }
5663 }
5664
5665 // Drain the queue - which may cause stealing
5666 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5667 drain_queue.do_void();
5668 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5669 assert(pss.refs()->is_empty(), "should be");
5670 }
5671 };
5672
5673 // Weak Reference processing during an evacuation pause (part 1).
5674 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5675 double ref_proc_start = os::elapsedTime();
5676
5677 ReferenceProcessor* rp = _ref_processor_stw;
5678 assert(rp->discovery_enabled(), "should have been enabled");
5679
5680 // Any reference objects, in the collection set, that were 'discovered'
5681 // by the CM ref processor should have already been copied (either by
5682 // applying the external root copy closure to the discovered lists, or
5683 // by following an RSet entry).
5684 //
5685 // But some of the referents, that are in the collection set, that these
5686 // reference objects point to may not have been copied: the STW ref
5687 // processor would have seen that the reference object had already
5688 // been 'discovered' and would have skipped discovering the reference,
5689 // but would not have treated the reference object as a regular oop.
5690 // As a result the copy closure would not have been applied to the
5691 // referent object.
5692 //
5693 // We need to explicitly copy these referent objects - the references
5694 // will be processed at the end of remarking.
5695 //
5696 // We also need to do this copying before we process the reference
5697 // objects discovered by the STW ref processor in case one of these
5698 // referents points to another object which is also referenced by an
5699 // object discovered by the STW ref processor.
5700
5701 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5702 no_of_gc_workers == workers()->active_workers(),
5703 "Need to reset active GC workers");
5704
5705 set_par_threads(no_of_gc_workers);
5706 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5707 no_of_gc_workers,
5708 _task_queues);
5709
5710 if (G1CollectedHeap::use_parallel_gc_threads()) {
5711 workers()->run_task(&keep_cm_referents);
5712 } else {
5713 keep_cm_referents.work(0);
5714 }
5715
5716 set_par_threads(0);
5717
5718 // Closure to test whether a referent is alive.
5719 G1STWIsAliveClosure is_alive(this);
5720
5721 // Even when parallel reference processing is enabled, the processing
5722 // of JNI refs is serial and performed serially by the current thread
5723 // rather than by a worker. The following PSS will be used for processing
5724 // JNI refs.
5725
5726 // Use only a single queue for this PSS.
5727 G1ParScanThreadState pss(this, 0, NULL);
5728
5729 // We do not embed a reference processor in the copying/scanning
5730 // closures while we're actually processing the discovered
5731 // reference objects.
5732 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5733 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5734 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5735
5736 pss.set_evac_closure(&scan_evac_cl);
5737 pss.set_evac_failure_closure(&evac_failure_cl);
5738 pss.set_partial_scan_closure(&partial_scan_cl);
5739
5740 assert(pss.refs()->is_empty(), "pre-condition");
5741
5742 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5743 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5744
5745 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5746 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5747
5748 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5749 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5750
5751 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5752 // We also need to mark copied objects.
5753 copy_non_heap_cl = ©_mark_non_heap_cl;
5754 copy_metadata_cl = ©_mark_metadata_cl;
5755 }
5756
5757 // Keep alive closure.
5758 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5759
5760 // Serial Complete GC closure
5761 G1STWDrainQueueClosure drain_queue(this, &pss);
5762
5763 // Setup the soft refs policy...
5764 rp->setup_policy(false);
5765
5766 ReferenceProcessorStats stats;
5767 if (!rp->processing_is_mt()) {
5768 // Serial reference processing...
5769 stats = rp->process_discovered_references(&is_alive,
5770 &keep_alive,
5771 &drain_queue,
5772 NULL,
5773 _gc_timer_stw);
5774 } else {
5775 // Parallel reference processing
5776 assert(rp->num_q() == no_of_gc_workers, "sanity");
5777 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5778
5779 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5780 stats = rp->process_discovered_references(&is_alive,
5781 &keep_alive,
5782 &drain_queue,
5783 &par_task_executor,
5784 _gc_timer_stw);
5785 }
5786
5787 _gc_tracer_stw->report_gc_reference_stats(stats);
5788 // We have completed copying any necessary live referent objects
5789 // (that were not copied during the actual pause) so we can
5790 // retire any active alloc buffers
5791 pss.retire_alloc_buffers();
5792 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5793
5794 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5795 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5796 }
5797
5798 // Weak Reference processing during an evacuation pause (part 2).
5799 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5800 double ref_enq_start = os::elapsedTime();
5801
5802 ReferenceProcessor* rp = _ref_processor_stw;
5803 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5804
5805 // Now enqueue any remaining on the discovered lists on to
5806 // the pending list.
5807 if (!rp->processing_is_mt()) {
5808 // Serial reference processing...
5809 rp->enqueue_discovered_references();
5810 } else {
5811 // Parallel reference enqueueing
5812
5813 assert(no_of_gc_workers == workers()->active_workers(),
5814 "Need to reset active workers");
5815 assert(rp->num_q() == no_of_gc_workers, "sanity");
5816 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5817
5818 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5819 rp->enqueue_discovered_references(&par_task_executor);
5820 }
5821
5822 rp->verify_no_references_recorded();
5823 assert(!rp->discovery_enabled(), "should have been disabled");
5824
5825 // FIXME
5826 // CM's reference processing also cleans up the string and symbol tables.
5827 // Should we do that here also? We could, but it is a serial operation
5828 // and could significantly increase the pause time.
5829
5830 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5831 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5832 }
5833
5834 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5835 _expand_heap_after_alloc_failure = true;
5836 _evacuation_failed = false;
5837
5838 // Should G1EvacuationFailureALot be in effect for this GC?
5839 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5840
5841 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5842
5843 // Disable the hot card cache.
5844 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5845 hot_card_cache->reset_hot_cache_claimed_index();
5846 hot_card_cache->set_use_cache(false);
5847
5848 uint n_workers;
5849 if (G1CollectedHeap::use_parallel_gc_threads()) {
5850 n_workers =
5851 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5852 workers()->active_workers(),
5853 Threads::number_of_non_daemon_threads());
5854 assert(UseDynamicNumberOfGCThreads ||
5855 n_workers == workers()->total_workers(),
5856 "If not dynamic should be using all the workers");
5857 workers()->set_active_workers(n_workers);
5858 set_par_threads(n_workers);
5859 } else {
5860 assert(n_par_threads() == 0,
5861 "Should be the original non-parallel value");
5862 n_workers = 1;
5863 }
5864
5865 G1ParTask g1_par_task(this, _task_queues);
5866
5867 init_for_evac_failure(NULL);
5868
5869 rem_set()->prepare_for_younger_refs_iterate(true);
5870
5871 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5872 double start_par_time_sec = os::elapsedTime();
5873 double end_par_time_sec;
5874
5875 {
5876 StrongRootsScope srs(this);
5877
5878 if (G1CollectedHeap::use_parallel_gc_threads()) {
5879 // The individual threads will set their evac-failure closures.
5880 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5881 // These tasks use ShareHeap::_process_strong_tasks
5882 assert(UseDynamicNumberOfGCThreads ||
5883 workers()->active_workers() == workers()->total_workers(),
5884 "If not dynamic should be using all the workers");
5885 workers()->run_task(&g1_par_task);
5886 } else {
5887 g1_par_task.set_for_termination(n_workers);
5888 g1_par_task.work(0);
5889 }
5890 end_par_time_sec = os::elapsedTime();
5891
5892 // Closing the inner scope will execute the destructor
5893 // for the StrongRootsScope object. We record the current
5894 // elapsed time before closing the scope so that time
5895 // taken for the SRS destructor is NOT included in the
5896 // reported parallel time.
5897 }
5898
5899 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5900 g1_policy()->phase_times()->record_par_time(par_time_ms);
5901
5902 double code_root_fixup_time_ms =
5903 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5904 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5905
5906 set_par_threads(0);
5907
5908 // Process any discovered reference objects - we have
5909 // to do this _before_ we retire the GC alloc regions
5910 // as we may have to copy some 'reachable' referent
5911 // objects (and their reachable sub-graphs) that were
5912 // not copied during the pause.
5913 process_discovered_references(n_workers);
5914
5915 // Weak root processing.
5916 {
5917 G1STWIsAliveClosure is_alive(this);
5918 G1KeepAliveClosure keep_alive(this);
5919 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5920 }
5921
5922 release_gc_alloc_regions(n_workers, evacuation_info);
5923 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5924
5925 // Reset and re-enable the hot card cache.
5926 // Note the counts for the cards in the regions in the
5927 // collection set are reset when the collection set is freed.
5928 hot_card_cache->reset_hot_cache();
5929 hot_card_cache->set_use_cache(true);
5930
5931 // Migrate the strong code roots attached to each region in
5932 // the collection set. Ideally we would like to do this
5933 // after we have finished the scanning/evacuation of the
5934 // strong code roots for a particular heap region.
5935 migrate_strong_code_roots();
5936
5937 if (g1_policy()->during_initial_mark_pause()) {
5938 // Reset the claim values set during marking the strong code roots
5939 reset_heap_region_claim_values();
5940 }
5941
5942 finalize_for_evac_failure();
5943
5944 if (evacuation_failed()) {
5945 remove_self_forwarding_pointers();
5946
5947 // Reset the G1EvacuationFailureALot counters and flags
5948 // Note: the values are reset only when an actual
5949 // evacuation failure occurs.
5950 NOT_PRODUCT(reset_evacuation_should_fail();)
5951 }
5952
5953 // Enqueue any remaining references remaining on the STW
5954 // reference processor's discovered lists. We need to do
5955 // this after the card table is cleaned (and verified) as
5956 // the act of enqueueing entries on to the pending list
5957 // will log these updates (and dirty their associated
5958 // cards). We need these updates logged to update any
5959 // RSets.
5960 enqueue_discovered_references(n_workers);
5961
5962 if (G1DeferredRSUpdate) {
5963 RedirtyLoggedCardTableEntryFastClosure redirty;
5964 dirty_card_queue_set().set_closure(&redirty);
5965 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5966
5967 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5968 dcq.merge_bufferlists(&dirty_card_queue_set());
5969 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5970 }
5971 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5972 }
5973
5974 void G1CollectedHeap::free_region(HeapRegion* hr,
5975 FreeRegionList* free_list,
5976 bool par) {
5977 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5978 assert(!hr->is_empty(), "the region should not be empty");
5979 assert(free_list != NULL, "pre-condition");
5980
5981 // Clear the card counts for this region.
5982 // Note: we only need to do this if the region is not young
5983 // (since we don't refine cards in young regions).
5984 if (!hr->is_young()) {
5985 _cg1r->hot_card_cache()->reset_card_counts(hr);
5986 }
5987 hr->hr_clear(par, true /* clear_space */);
5988 free_list->add_as_head(hr);
5989 }
5990
5991 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5992 FreeRegionList* free_list,
5993 bool par) {
5994 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5995 assert(free_list != NULL, "pre-condition");
5996
5997 size_t hr_capacity = hr->capacity();
5998 // We need to read this before we make the region non-humongous,
5999 // otherwise the information will be gone.
6000 uint last_index = hr->last_hc_index();
6001 hr->set_notHumongous();
6002 free_region(hr, free_list, par);
6003
6004 uint i = hr->hrs_index() + 1;
6005 while (i < last_index) {
6006 HeapRegion* curr_hr = region_at(i);
6007 assert(curr_hr->continuesHumongous(), "invariant");
6008 curr_hr->set_notHumongous();
6009 free_region(curr_hr, free_list, par);
6010 i += 1;
6011 }
6012 }
6013
6014 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6015 const HeapRegionSetCount& humongous_regions_removed) {
6016 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6017 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6018 _old_set.bulk_remove(old_regions_removed);
6019 _humongous_set.bulk_remove(humongous_regions_removed);
6020 }
6021
6022 }
6023
6024 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6025 assert(list != NULL, "list can't be null");
6026 if (!list->is_empty()) {
6027 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6028 _free_list.add_as_head(list);
6029 }
6030 }
6031
6032 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6033 assert(_summary_bytes_used >= bytes,
6034 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6035 _summary_bytes_used, bytes));
6036 _summary_bytes_used -= bytes;
6037 }
6038
6039 class G1ParCleanupCTTask : public AbstractGangTask {
6040 G1SATBCardTableModRefBS* _ct_bs;
6041 G1CollectedHeap* _g1h;
6042 HeapRegion* volatile _su_head;
6043 public:
6044 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6045 G1CollectedHeap* g1h) :
6046 AbstractGangTask("G1 Par Cleanup CT Task"),
6047 _ct_bs(ct_bs), _g1h(g1h) { }
6048
6049 void work(uint worker_id) {
6050 HeapRegion* r;
6051 while (r = _g1h->pop_dirty_cards_region()) {
6052 clear_cards(r);
6053 }
6054 }
6055
6056 void clear_cards(HeapRegion* r) {
6057 // Cards of the survivors should have already been dirtied.
6058 if (!r->is_survivor()) {
6059 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6060 }
6061 }
6062 };
6063
6064 #ifndef PRODUCT
6065 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6066 G1CollectedHeap* _g1h;
6067 G1SATBCardTableModRefBS* _ct_bs;
6068 public:
6069 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6070 : _g1h(g1h), _ct_bs(ct_bs) { }
6071 virtual bool doHeapRegion(HeapRegion* r) {
6072 if (r->is_survivor()) {
6073 _g1h->verify_dirty_region(r);
6074 } else {
6075 _g1h->verify_not_dirty_region(r);
6076 }
6077 return false;
6078 }
6079 };
6080
6081 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6082 // All of the region should be clean.
6083 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6084 MemRegion mr(hr->bottom(), hr->end());
6085 ct_bs->verify_not_dirty_region(mr);
6086 }
6087
6088 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6089 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6090 // dirty allocated blocks as they allocate them. The thread that
6091 // retires each region and replaces it with a new one will do a
6092 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6093 // not dirty that area (one less thing to have to do while holding
6094 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6095 // is dirty.
6096 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6097 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6098 if (hr->is_young()) {
6099 ct_bs->verify_g1_young_region(mr);
6100 } else {
6101 ct_bs->verify_dirty_region(mr);
6102 }
6103 }
6104
6105 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6106 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6107 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6108 verify_dirty_region(hr);
6109 }
6110 }
6111
6112 void G1CollectedHeap::verify_dirty_young_regions() {
6113 verify_dirty_young_list(_young_list->first_region());
6114 }
6115 #endif
6116
6117 void G1CollectedHeap::cleanUpCardTable() {
6118 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6119 double start = os::elapsedTime();
6120
6121 {
6122 // Iterate over the dirty cards region list.
6123 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6124
6125 if (G1CollectedHeap::use_parallel_gc_threads()) {
6126 set_par_threads();
6127 workers()->run_task(&cleanup_task);
6128 set_par_threads(0);
6129 } else {
6130 while (_dirty_cards_region_list) {
6131 HeapRegion* r = _dirty_cards_region_list;
6132 cleanup_task.clear_cards(r);
6133 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6134 if (_dirty_cards_region_list == r) {
6135 // The last region.
6136 _dirty_cards_region_list = NULL;
6137 }
6138 r->set_next_dirty_cards_region(NULL);
6139 }
6140 }
6141 #ifndef PRODUCT
6142 if (G1VerifyCTCleanup || VerifyAfterGC) {
6143 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6144 heap_region_iterate(&cleanup_verifier);
6145 }
6146 #endif
6147 }
6148
6149 double elapsed = os::elapsedTime() - start;
6150 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6151 }
6152
6153 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6154 size_t pre_used = 0;
6155 FreeRegionList local_free_list("Local List for CSet Freeing");
6156
6157 double young_time_ms = 0.0;
6158 double non_young_time_ms = 0.0;
6159
6160 // Since the collection set is a superset of the the young list,
6161 // all we need to do to clear the young list is clear its
6162 // head and length, and unlink any young regions in the code below
6163 _young_list->clear();
6164
6165 G1CollectorPolicy* policy = g1_policy();
6166
6167 double start_sec = os::elapsedTime();
6168 bool non_young = true;
6169
6170 HeapRegion* cur = cs_head;
6171 int age_bound = -1;
6172 size_t rs_lengths = 0;
6173
6174 while (cur != NULL) {
6175 assert(!is_on_master_free_list(cur), "sanity");
6176 if (non_young) {
6177 if (cur->is_young()) {
6178 double end_sec = os::elapsedTime();
6179 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6180 non_young_time_ms += elapsed_ms;
6181
6182 start_sec = os::elapsedTime();
6183 non_young = false;
6184 }
6185 } else {
6186 if (!cur->is_young()) {
6187 double end_sec = os::elapsedTime();
6188 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6189 young_time_ms += elapsed_ms;
6190
6191 start_sec = os::elapsedTime();
6192 non_young = true;
6193 }
6194 }
6195
6196 rs_lengths += cur->rem_set()->occupied();
6197
6198 HeapRegion* next = cur->next_in_collection_set();
6199 assert(cur->in_collection_set(), "bad CS");
6200 cur->set_next_in_collection_set(NULL);
6201 cur->set_in_collection_set(false);
6202
6203 if (cur->is_young()) {
6204 int index = cur->young_index_in_cset();
6205 assert(index != -1, "invariant");
6206 assert((uint) index < policy->young_cset_region_length(), "invariant");
6207 size_t words_survived = _surviving_young_words[index];
6208 cur->record_surv_words_in_group(words_survived);
6209
6210 // At this point the we have 'popped' cur from the collection set
6211 // (linked via next_in_collection_set()) but it is still in the
6212 // young list (linked via next_young_region()). Clear the
6213 // _next_young_region field.
6214 cur->set_next_young_region(NULL);
6215 } else {
6216 int index = cur->young_index_in_cset();
6217 assert(index == -1, "invariant");
6218 }
6219
6220 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6221 (!cur->is_young() && cur->young_index_in_cset() == -1),
6222 "invariant" );
6223
6224 if (!cur->evacuation_failed()) {
6225 MemRegion used_mr = cur->used_region();
6226
6227 // And the region is empty.
6228 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6229 pre_used += cur->used();
6230 free_region(cur, &local_free_list, false /* par */);
6231 } else {
6232 cur->uninstall_surv_rate_group();
6233 if (cur->is_young()) {
6234 cur->set_young_index_in_cset(-1);
6235 }
6236 cur->set_not_young();
6237 cur->set_evacuation_failed(false);
6238 // The region is now considered to be old.
6239 _old_set.add(cur);
6240 evacuation_info.increment_collectionset_used_after(cur->used());
6241 }
6242 cur = next;
6243 }
6244
6245 evacuation_info.set_regions_freed(local_free_list.length());
6246 policy->record_max_rs_lengths(rs_lengths);
6247 policy->cset_regions_freed();
6248
6249 double end_sec = os::elapsedTime();
6250 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6251
6252 if (non_young) {
6253 non_young_time_ms += elapsed_ms;
6254 } else {
6255 young_time_ms += elapsed_ms;
6256 }
6257
6258 prepend_to_freelist(&local_free_list);
6259 decrement_summary_bytes(pre_used);
6260 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6261 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6262 }
6263
6264 // This routine is similar to the above but does not record
6265 // any policy statistics or update free lists; we are abandoning
6266 // the current incremental collection set in preparation of a
6267 // full collection. After the full GC we will start to build up
6268 // the incremental collection set again.
6269 // This is only called when we're doing a full collection
6270 // and is immediately followed by the tearing down of the young list.
6271
6272 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6273 HeapRegion* cur = cs_head;
6274
6275 while (cur != NULL) {
6276 HeapRegion* next = cur->next_in_collection_set();
6277 assert(cur->in_collection_set(), "bad CS");
6278 cur->set_next_in_collection_set(NULL);
6279 cur->set_in_collection_set(false);
6280 cur->set_young_index_in_cset(-1);
6281 cur = next;
6282 }
6283 }
6284
6285 void G1CollectedHeap::set_free_regions_coming() {
6286 if (G1ConcRegionFreeingVerbose) {
6287 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6288 "setting free regions coming");
6289 }
6290
6291 assert(!free_regions_coming(), "pre-condition");
6292 _free_regions_coming = true;
6293 }
6294
6295 void G1CollectedHeap::reset_free_regions_coming() {
6296 assert(free_regions_coming(), "pre-condition");
6297
6298 {
6299 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6300 _free_regions_coming = false;
6301 SecondaryFreeList_lock->notify_all();
6302 }
6303
6304 if (G1ConcRegionFreeingVerbose) {
6305 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6306 "reset free regions coming");
6307 }
6308 }
6309
6310 void G1CollectedHeap::wait_while_free_regions_coming() {
6311 // Most of the time we won't have to wait, so let's do a quick test
6312 // first before we take the lock.
6313 if (!free_regions_coming()) {
6314 return;
6315 }
6316
6317 if (G1ConcRegionFreeingVerbose) {
6318 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6319 "waiting for free regions");
6320 }
6321
6322 {
6323 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6324 while (free_regions_coming()) {
6325 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6326 }
6327 }
6328
6329 if (G1ConcRegionFreeingVerbose) {
6330 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6331 "done waiting for free regions");
6332 }
6333 }
6334
6335 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6336 assert(heap_lock_held_for_gc(),
6337 "the heap lock should already be held by or for this thread");
6338 _young_list->push_region(hr);
6339 }
6340
6341 class NoYoungRegionsClosure: public HeapRegionClosure {
6342 private:
6343 bool _success;
6344 public:
6345 NoYoungRegionsClosure() : _success(true) { }
6346 bool doHeapRegion(HeapRegion* r) {
6347 if (r->is_young()) {
6348 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6349 r->bottom(), r->end());
6350 _success = false;
6351 }
6352 return false;
6353 }
6354 bool success() { return _success; }
6355 };
6356
6357 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6358 bool ret = _young_list->check_list_empty(check_sample);
6359
6360 if (check_heap) {
6361 NoYoungRegionsClosure closure;
6362 heap_region_iterate(&closure);
6363 ret = ret && closure.success();
6364 }
6365
6366 return ret;
6367 }
6368
6369 class TearDownRegionSetsClosure : public HeapRegionClosure {
6370 private:
6371 HeapRegionSet *_old_set;
6372
6373 public:
6374 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6375
6376 bool doHeapRegion(HeapRegion* r) {
6377 if (r->is_empty()) {
6378 // We ignore empty regions, we'll empty the free list afterwards
6379 } else if (r->is_young()) {
6380 // We ignore young regions, we'll empty the young list afterwards
6381 } else if (r->isHumongous()) {
6382 // We ignore humongous regions, we're not tearing down the
6383 // humongous region set
6384 } else {
6385 // The rest should be old
6386 _old_set->remove(r);
6387 }
6388 return false;
6389 }
6390
6391 ~TearDownRegionSetsClosure() {
6392 assert(_old_set->is_empty(), "post-condition");
6393 }
6394 };
6395
6396 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6397 assert_at_safepoint(true /* should_be_vm_thread */);
6398
6399 if (!free_list_only) {
6400 TearDownRegionSetsClosure cl(&_old_set);
6401 heap_region_iterate(&cl);
6402
6403 // Need to do this after the heap iteration to be able to
6404 // recognize the young regions and ignore them during the iteration.
6405 _young_list->empty_list();
6406 }
6407 _free_list.remove_all();
6408 }
6409
6410 class RebuildRegionSetsClosure : public HeapRegionClosure {
6411 private:
6412 bool _free_list_only;
6413 HeapRegionSet* _old_set;
6414 FreeRegionList* _free_list;
6415 size_t _total_used;
6416
6417 public:
6418 RebuildRegionSetsClosure(bool free_list_only,
6419 HeapRegionSet* old_set, FreeRegionList* free_list) :
6420 _free_list_only(free_list_only),
6421 _old_set(old_set), _free_list(free_list), _total_used(0) {
6422 assert(_free_list->is_empty(), "pre-condition");
6423 if (!free_list_only) {
6424 assert(_old_set->is_empty(), "pre-condition");
6425 }
6426 }
6427
6428 bool doHeapRegion(HeapRegion* r) {
6429 if (r->continuesHumongous()) {
6430 return false;
6431 }
6432
6433 if (r->is_empty()) {
6434 // Add free regions to the free list
6435 _free_list->add_as_tail(r);
6436 } else if (!_free_list_only) {
6437 assert(!r->is_young(), "we should not come across young regions");
6438
6439 if (r->isHumongous()) {
6440 // We ignore humongous regions, we left the humongous set unchanged
6441 } else {
6442 // The rest should be old, add them to the old set
6443 _old_set->add(r);
6444 }
6445 _total_used += r->used();
6446 }
6447
6448 return false;
6449 }
6450
6451 size_t total_used() {
6452 return _total_used;
6453 }
6454 };
6455
6456 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6457 assert_at_safepoint(true /* should_be_vm_thread */);
6458
6459 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6460 heap_region_iterate(&cl);
6461
6462 if (!free_list_only) {
6463 _summary_bytes_used = cl.total_used();
6464 }
6465 assert(_summary_bytes_used == recalculate_used(),
6466 err_msg("inconsistent _summary_bytes_used, "
6467 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6468 _summary_bytes_used, recalculate_used()));
6469 }
6470
6471 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6472 _refine_cte_cl->set_concurrent(concurrent);
6473 }
6474
6475 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6476 HeapRegion* hr = heap_region_containing(p);
6477 if (hr == NULL) {
6478 return false;
6479 } else {
6480 return hr->is_in(p);
6481 }
6482 }
6483
6484 // Methods for the mutator alloc region
6485
6486 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6487 bool force) {
6488 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6489 assert(!force || g1_policy()->can_expand_young_list(),
6490 "if force is true we should be able to expand the young list");
6491 bool young_list_full = g1_policy()->is_young_list_full();
6492 if (force || !young_list_full) {
6493 HeapRegion* new_alloc_region = new_region(word_size,
6494 false /* do_expand */);
6495 if (new_alloc_region != NULL) {
6496 set_region_short_lived_locked(new_alloc_region);
6497 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6498 return new_alloc_region;
6499 }
6500 }
6501 return NULL;
6502 }
6503
6504 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6505 size_t allocated_bytes) {
6506 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6507 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6508
6509 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6510 _summary_bytes_used += allocated_bytes;
6511 _hr_printer.retire(alloc_region);
6512 // We update the eden sizes here, when the region is retired,
6513 // instead of when it's allocated, since this is the point that its
6514 // used space has been recored in _summary_bytes_used.
6515 g1mm()->update_eden_size();
6516 }
6517
6518 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6519 bool force) {
6520 return _g1h->new_mutator_alloc_region(word_size, force);
6521 }
6522
6523 void G1CollectedHeap::set_par_threads() {
6524 // Don't change the number of workers. Use the value previously set
6525 // in the workgroup.
6526 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6527 uint n_workers = workers()->active_workers();
6528 assert(UseDynamicNumberOfGCThreads ||
6529 n_workers == workers()->total_workers(),
6530 "Otherwise should be using the total number of workers");
6531 if (n_workers == 0) {
6532 assert(false, "Should have been set in prior evacuation pause.");
6533 n_workers = ParallelGCThreads;
6534 workers()->set_active_workers(n_workers);
6535 }
6536 set_par_threads(n_workers);
6537 }
6538
6539 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6540 size_t allocated_bytes) {
6541 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6542 }
6543
6544 // Methods for the GC alloc regions
6545
6546 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6547 uint count,
6548 GCAllocPurpose ap) {
6549 assert(FreeList_lock->owned_by_self(), "pre-condition");
6550
6551 if (count < g1_policy()->max_regions(ap)) {
6552 HeapRegion* new_alloc_region = new_region(word_size,
6553 true /* do_expand */);
6554 if (new_alloc_region != NULL) {
6555 // We really only need to do this for old regions given that we
6556 // should never scan survivors. But it doesn't hurt to do it
6557 // for survivors too.
6558 new_alloc_region->set_saved_mark();
6559 if (ap == GCAllocForSurvived) {
6560 new_alloc_region->set_survivor();
6561 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6562 } else {
6563 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6564 }
6565 bool during_im = g1_policy()->during_initial_mark_pause();
6566 new_alloc_region->note_start_of_copying(during_im);
6567 return new_alloc_region;
6568 } else {
6569 g1_policy()->note_alloc_region_limit_reached(ap);
6570 }
6571 }
6572 return NULL;
6573 }
6574
6575 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6576 size_t allocated_bytes,
6577 GCAllocPurpose ap) {
6578 bool during_im = g1_policy()->during_initial_mark_pause();
6579 alloc_region->note_end_of_copying(during_im);
6580 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6581 if (ap == GCAllocForSurvived) {
6582 young_list()->add_survivor_region(alloc_region);
6583 } else {
6584 _old_set.add(alloc_region);
6585 }
6586 _hr_printer.retire(alloc_region);
6587 }
6588
6589 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6590 bool force) {
6591 assert(!force, "not supported for GC alloc regions");
6592 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6593 }
6594
6595 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6596 size_t allocated_bytes) {
6597 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6598 GCAllocForSurvived);
6599 }
6600
6601 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6602 bool force) {
6603 assert(!force, "not supported for GC alloc regions");
6604 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6605 }
6606
6607 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6608 size_t allocated_bytes) {
6609 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6610 GCAllocForTenured);
6611 }
6612 // Heap region set verification
6613
6614 class VerifyRegionListsClosure : public HeapRegionClosure {
6615 private:
6616 HeapRegionSet* _old_set;
6617 HeapRegionSet* _humongous_set;
6618 FreeRegionList* _free_list;
6619
6620 public:
6621 HeapRegionSetCount _old_count;
6622 HeapRegionSetCount _humongous_count;
6623 HeapRegionSetCount _free_count;
6624
6625 VerifyRegionListsClosure(HeapRegionSet* old_set,
6626 HeapRegionSet* humongous_set,
6627 FreeRegionList* free_list) :
6628 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6629 _old_count(), _humongous_count(), _free_count(){ }
6630
6631 bool doHeapRegion(HeapRegion* hr) {
6632 if (hr->continuesHumongous()) {
6633 return false;
6634 }
6635
6636 if (hr->is_young()) {
6637 // TODO
6638 } else if (hr->startsHumongous()) {
6639 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num()));
6640 _humongous_count.increment(1u, hr->capacity());
6641 } else if (hr->is_empty()) {
6642 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num()));
6643 _free_count.increment(1u, hr->capacity());
6644 } else {
6645 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num()));
6646 _old_count.increment(1u, hr->capacity());
6647 }
6648 return false;
6649 }
6650
6651 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6652 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6653 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6654 old_set->total_capacity_bytes(), _old_count.capacity()));
6655
6656 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6657 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6658 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6659
6660 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6661 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6662 free_list->total_capacity_bytes(), _free_count.capacity()));
6663 }
6664 };
6665
6666 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6667 HeapWord* bottom) {
6668 HeapWord* end = bottom + HeapRegion::GrainWords;
6669 MemRegion mr(bottom, end);
6670 assert(_g1_reserved.contains(mr), "invariant");
6671 // This might return NULL if the allocation fails
6672 return new HeapRegion(hrs_index, _bot_shared, mr);
6673 }
6674
6675 void G1CollectedHeap::verify_region_sets() {
6676 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6677
6678 // First, check the explicit lists.
6679 _free_list.verify_list();
6680 {
6681 // Given that a concurrent operation might be adding regions to
6682 // the secondary free list we have to take the lock before
6683 // verifying it.
6684 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6685 _secondary_free_list.verify_list();
6686 }
6687
6688 // If a concurrent region freeing operation is in progress it will
6689 // be difficult to correctly attributed any free regions we come
6690 // across to the correct free list given that they might belong to
6691 // one of several (free_list, secondary_free_list, any local lists,
6692 // etc.). So, if that's the case we will skip the rest of the
6693 // verification operation. Alternatively, waiting for the concurrent
6694 // operation to complete will have a non-trivial effect on the GC's
6695 // operation (no concurrent operation will last longer than the
6696 // interval between two calls to verification) and it might hide
6697 // any issues that we would like to catch during testing.
6698 if (free_regions_coming()) {
6699 return;
6700 }
6701
6702 // Make sure we append the secondary_free_list on the free_list so
6703 // that all free regions we will come across can be safely
6704 // attributed to the free_list.
6705 append_secondary_free_list_if_not_empty_with_lock();
6706
6707 // Finally, make sure that the region accounting in the lists is
6708 // consistent with what we see in the heap.
6709
6710 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6711 heap_region_iterate(&cl);
6712 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6713 }
6714
6715 // Optimized nmethod scanning
6716
6717 class RegisterNMethodOopClosure: public OopClosure {
6718 G1CollectedHeap* _g1h;
6719 nmethod* _nm;
6720
6721 template <class T> void do_oop_work(T* p) {
6722 T heap_oop = oopDesc::load_heap_oop(p);
6723 if (!oopDesc::is_null(heap_oop)) {
6724 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6725 HeapRegion* hr = _g1h->heap_region_containing(obj);
6726 assert(!hr->continuesHumongous(),
6727 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6728 " starting at "HR_FORMAT,
6729 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6730
6731 // HeapRegion::add_strong_code_root() avoids adding duplicate
6732 // entries but having duplicates is OK since we "mark" nmethods
6733 // as visited when we scan the strong code root lists during the GC.
6734 hr->add_strong_code_root(_nm);
6735 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6736 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6737 _nm, HR_FORMAT_PARAMS(hr)));
6738 }
6739 }
6740
6741 public:
6742 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6743 _g1h(g1h), _nm(nm) {}
6744
6745 void do_oop(oop* p) { do_oop_work(p); }
6746 void do_oop(narrowOop* p) { do_oop_work(p); }
6747 };
6748
6749 class UnregisterNMethodOopClosure: public OopClosure {
6750 G1CollectedHeap* _g1h;
6751 nmethod* _nm;
6752
6753 template <class T> void do_oop_work(T* p) {
6754 T heap_oop = oopDesc::load_heap_oop(p);
6755 if (!oopDesc::is_null(heap_oop)) {
6756 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6757 HeapRegion* hr = _g1h->heap_region_containing(obj);
6758 assert(!hr->continuesHumongous(),
6759 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6760 " starting at "HR_FORMAT,
6761 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6762
6763 hr->remove_strong_code_root(_nm);
6764 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6765 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6766 _nm, HR_FORMAT_PARAMS(hr)));
6767 }
6768 }
6769
6770 public:
6771 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6772 _g1h(g1h), _nm(nm) {}
6773
6774 void do_oop(oop* p) { do_oop_work(p); }
6775 void do_oop(narrowOop* p) { do_oop_work(p); }
6776 };
6777
6778 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6779 CollectedHeap::register_nmethod(nm);
6780
6781 guarantee(nm != NULL, "sanity");
6782 RegisterNMethodOopClosure reg_cl(this, nm);
6783 nm->oops_do(®_cl);
6784 }
6785
6786 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6787 CollectedHeap::unregister_nmethod(nm);
6788
6789 guarantee(nm != NULL, "sanity");
6790 UnregisterNMethodOopClosure reg_cl(this, nm);
6791 nm->oops_do(®_cl, true);
6792 }
6793
6794 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6795 public:
6796 bool doHeapRegion(HeapRegion *hr) {
6797 assert(!hr->isHumongous(),
6798 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6799 HR_FORMAT_PARAMS(hr)));
6800 hr->migrate_strong_code_roots();
6801 return false;
6802 }
6803 };
6804
6805 void G1CollectedHeap::migrate_strong_code_roots() {
6806 MigrateCodeRootsHeapRegionClosure cl;
6807 double migrate_start = os::elapsedTime();
6808 collection_set_iterate(&cl);
6809 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6810 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6811 }
6812
6813 // Mark all the code roots that point into regions *not* in the
6814 // collection set.
6815 //
6816 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6817 // walking the the code roots lists of regions not in the collection
6818 // set. Suppose we have an nmethod (M) that points to objects in two
6819 // separate regions - one in the collection set (R1) and one not (R2).
6820 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6821 // nmethod M when walking the code roots for R1. When we come to scan
6822 // the code roots for R2, we would see that M is already marked and it
6823 // would be skipped and the objects in R2 that are referenced from M
6824 // would not be evacuated.
6825
6826 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6827
6828 class MarkStrongCodeRootOopClosure: public OopClosure {
6829 ConcurrentMark* _cm;
6830 HeapRegion* _hr;
6831 uint _worker_id;
6832
6833 template <class T> void do_oop_work(T* p) {
6834 T heap_oop = oopDesc::load_heap_oop(p);
6835 if (!oopDesc::is_null(heap_oop)) {
6836 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6837 // Only mark objects in the region (which is assumed
6838 // to be not in the collection set).
6839 if (_hr->is_in(obj)) {
6840 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6841 }
6842 }
6843 }
6844
6845 public:
6846 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6847 _cm(cm), _hr(hr), _worker_id(worker_id) {
6848 assert(!_hr->in_collection_set(), "sanity");
6849 }
6850
6851 void do_oop(narrowOop* p) { do_oop_work(p); }
6852 void do_oop(oop* p) { do_oop_work(p); }
6853 };
6854
6855 MarkStrongCodeRootOopClosure _oop_cl;
6856
6857 public:
6858 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6859 _oop_cl(cm, hr, worker_id) {}
6860
6861 void do_code_blob(CodeBlob* cb) {
6862 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6863 if (nm != NULL) {
6864 nm->oops_do(&_oop_cl);
6865 }
6866 }
6867 };
6868
6869 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6870 G1CollectedHeap* _g1h;
6871 uint _worker_id;
6872
6873 public:
6874 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6875 _g1h(g1h), _worker_id(worker_id) {}
6876
6877 bool doHeapRegion(HeapRegion *hr) {
6878 HeapRegionRemSet* hrrs = hr->rem_set();
6879 if (hr->continuesHumongous()) {
6880 // Code roots should never be attached to a continuation of a humongous region
6881 assert(hrrs->strong_code_roots_list_length() == 0,
6882 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6883 " starting at "HR_FORMAT", but has "INT32_FORMAT,
6884 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6885 hrrs->strong_code_roots_list_length()));
6886 return false;
6887 }
6888
6889 if (hr->in_collection_set()) {
6890 // Don't mark code roots into regions in the collection set here.
6891 // They will be marked when we scan them.
6892 return false;
6893 }
6894
6895 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6896 hr->strong_code_roots_do(&cb_cl);
6897 return false;
6898 }
6899 };
6900
6901 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6902 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6903 if (G1CollectedHeap::use_parallel_gc_threads()) {
6904 heap_region_par_iterate_chunked(&cl,
6905 worker_id,
6906 workers()->active_workers(),
6907 HeapRegion::ParMarkRootClaimValue);
6908 } else {
6909 heap_region_iterate(&cl);
6910 }
6911 }
6912
6913 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6914 G1CollectedHeap* _g1h;
6915
6916 public:
6917 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6918 _g1h(g1h) {}
6919
6920 void do_code_blob(CodeBlob* cb) {
6921 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6922 if (nm == NULL) {
6923 return;
6924 }
6925
6926 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6927 _g1h->register_nmethod(nm);
6928 }
6929 }
6930 };
6931
6932 void G1CollectedHeap::rebuild_strong_code_roots() {
6933 RebuildStrongCodeRootClosure blob_cl(this);
6934 CodeCache::blobs_do(&blob_cl);
6935 }