1 /*
2 * Copyright (c) 2001, 2013, 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/genOopClosures.inline.hpp"
54 #include "memory/generationSpec.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 HRSPhaseSetter x(HRSPhaseFullGC);
1302 verify_region_sets_optional();
1303
1304 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1305 collector_policy()->should_clear_all_soft_refs();
1306
1307 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1308
1309 {
1310 IsGCActiveMark x;
1311
1312 // Timing
1313 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1314 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1315 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1316
1317 {
1318 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1319 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1320 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1321
1322 double start = os::elapsedTime();
1323 g1_policy()->record_full_collection_start();
1324
1325 // Note: When we have a more flexible GC logging framework that
1326 // allows us to add optional attributes to a GC log record we
1327 // could consider timing and reporting how long we wait in the
1328 // following two methods.
1329 wait_while_free_regions_coming();
1330 // If we start the compaction before the CM threads finish
1331 // scanning the root regions we might trip them over as we'll
1332 // be moving objects / updating references. So let's wait until
1333 // they are done. By telling them to abort, they should complete
1334 // early.
1335 _cm->root_regions()->abort();
1336 _cm->root_regions()->wait_until_scan_finished();
1337 append_secondary_free_list_if_not_empty_with_lock();
1338
1339 gc_prologue(true);
1340 increment_total_collections(true /* full gc */);
1341 increment_old_marking_cycles_started();
1342
1343 assert(used() == recalculate_used(), "Should be equal");
1344
1345 verify_before_gc();
1346
1347 pre_full_gc_dump(gc_timer);
1348
1349 COMPILER2_PRESENT(DerivedPointerTable::clear());
1350
1351 // Disable discovery and empty the discovered lists
1352 // for the CM ref processor.
1353 ref_processor_cm()->disable_discovery();
1354 ref_processor_cm()->abandon_partial_discovery();
1355 ref_processor_cm()->verify_no_references_recorded();
1356
1357 // Abandon current iterations of concurrent marking and concurrent
1358 // refinement, if any are in progress. We have to do this before
1359 // wait_until_scan_finished() below.
1360 concurrent_mark()->abort();
1361
1362 // Make sure we'll choose a new allocation region afterwards.
1363 release_mutator_alloc_region();
1364 abandon_gc_alloc_regions();
1365 g1_rem_set()->cleanupHRRS();
1366
1367 // We should call this after we retire any currently active alloc
1368 // regions so that all the ALLOC / RETIRE events are generated
1369 // before the start GC event.
1370 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1371
1372 // We may have added regions to the current incremental collection
1373 // set between the last GC or pause and now. We need to clear the
1374 // incremental collection set and then start rebuilding it afresh
1375 // after this full GC.
1376 abandon_collection_set(g1_policy()->inc_cset_head());
1377 g1_policy()->clear_incremental_cset();
1378 g1_policy()->stop_incremental_cset_building();
1379
1380 tear_down_region_sets(false /* free_list_only */);
1381 g1_policy()->set_gcs_are_young(true);
1382
1383 // See the comments in g1CollectedHeap.hpp and
1384 // G1CollectedHeap::ref_processing_init() about
1385 // how reference processing currently works in G1.
1386
1387 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1388 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1389
1390 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1391 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1392
1393 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1394 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1395
1396 // Do collection work
1397 {
1398 HandleMark hm; // Discard invalid handles created during gc
1399 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1400 }
1401
1402 assert(free_regions() == 0, "we should not have added any free regions");
1403 rebuild_region_sets(false /* free_list_only */);
1404
1405 // Enqueue any discovered reference objects that have
1406 // not been removed from the discovered lists.
1407 ref_processor_stw()->enqueue_discovered_references();
1408
1409 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1410
1411 MemoryService::track_memory_usage();
1412
1413 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1414 ref_processor_stw()->verify_no_references_recorded();
1415
1416 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1417 ClassLoaderDataGraph::purge();
1418 MetaspaceAux::verify_metrics();
1419
1420 // Note: since we've just done a full GC, concurrent
1421 // marking is no longer active. Therefore we need not
1422 // re-enable reference discovery for the CM ref processor.
1423 // That will be done at the start of the next marking cycle.
1424 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1425 ref_processor_cm()->verify_no_references_recorded();
1426
1427 reset_gc_time_stamp();
1428 // Since everything potentially moved, we will clear all remembered
1429 // sets, and clear all cards. Later we will rebuild remembered
1430 // sets. We will also reset the GC time stamps of the regions.
1431 clear_rsets_post_compaction();
1432 check_gc_time_stamps();
1433
1434 // Resize the heap if necessary.
1435 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1436
1437 if (_hr_printer.is_active()) {
1438 // We should do this after we potentially resize the heap so
1439 // that all the COMMIT / UNCOMMIT events are generated before
1440 // the end GC event.
1441
1442 print_hrs_post_compaction();
1443 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1444 }
1445
1446 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1447 if (hot_card_cache->use_cache()) {
1448 hot_card_cache->reset_card_counts();
1449 hot_card_cache->reset_hot_cache();
1450 }
1451
1452 // Rebuild remembered sets of all regions.
1453 if (G1CollectedHeap::use_parallel_gc_threads()) {
1454 uint n_workers =
1455 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1456 workers()->active_workers(),
1457 Threads::number_of_non_daemon_threads());
1458 assert(UseDynamicNumberOfGCThreads ||
1459 n_workers == workers()->total_workers(),
1460 "If not dynamic should be using all the workers");
1461 workers()->set_active_workers(n_workers);
1462 // Set parallel threads in the heap (_n_par_threads) only
1463 // before a parallel phase and always reset it to 0 after
1464 // the phase so that the number of parallel threads does
1465 // no get carried forward to a serial phase where there
1466 // may be code that is "possibly_parallel".
1467 set_par_threads(n_workers);
1468
1469 ParRebuildRSTask rebuild_rs_task(this);
1470 assert(check_heap_region_claim_values(
1471 HeapRegion::InitialClaimValue), "sanity check");
1472 assert(UseDynamicNumberOfGCThreads ||
1473 workers()->active_workers() == workers()->total_workers(),
1474 "Unless dynamic should use total workers");
1475 // Use the most recent number of active workers
1476 assert(workers()->active_workers() > 0,
1477 "Active workers not properly set");
1478 set_par_threads(workers()->active_workers());
1479 workers()->run_task(&rebuild_rs_task);
1480 set_par_threads(0);
1481 assert(check_heap_region_claim_values(
1482 HeapRegion::RebuildRSClaimValue), "sanity check");
1483 reset_heap_region_claim_values();
1484 } else {
1485 RebuildRSOutOfRegionClosure rebuild_rs(this);
1486 heap_region_iterate(&rebuild_rs);
1487 }
1488
1489 // Rebuild the strong code root lists for each region
1490 rebuild_strong_code_roots();
1491
1492 if (true) { // FIXME
1493 MetaspaceGC::compute_new_size();
1494 }
1495
1496 #ifdef TRACESPINNING
1497 ParallelTaskTerminator::print_termination_counts();
1498 #endif
1499
1500 // Discard all rset updates
1501 JavaThread::dirty_card_queue_set().abandon_logs();
1502 assert(!G1DeferredRSUpdate
1503 || (G1DeferredRSUpdate &&
1504 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1505
1506 _young_list->reset_sampled_info();
1507 // At this point there should be no regions in the
1508 // entire heap tagged as young.
1509 assert(check_young_list_empty(true /* check_heap */),
1510 "young list should be empty at this point");
1511
1512 // Update the number of full collections that have been completed.
1513 increment_old_marking_cycles_completed(false /* concurrent */);
1514
1515 _hrs.verify_optional();
1516 verify_region_sets_optional();
1517
1518 verify_after_gc();
1519
1520 // Start a new incremental collection set for the next pause
1521 assert(g1_policy()->collection_set() == NULL, "must be");
1522 g1_policy()->start_incremental_cset_building();
1523
1524 // Clear the _cset_fast_test bitmap in anticipation of adding
1525 // regions to the incremental collection set for the next
1526 // evacuation pause.
1527 clear_cset_fast_test();
1528
1529 init_mutator_alloc_region();
1530
1531 double end = os::elapsedTime();
1532 g1_policy()->record_full_collection_end();
1533
1534 if (G1Log::fine()) {
1535 g1_policy()->print_heap_transition();
1536 }
1537
1538 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1539 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1540 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1541 // before any GC notifications are raised.
1542 g1mm()->update_sizes();
1543
1544 gc_epilogue(true);
1545 }
1546
1547 if (G1Log::finer()) {
1548 g1_policy()->print_detailed_heap_transition(true /* full */);
1549 }
1550
1551 print_heap_after_gc();
1552 trace_heap_after_gc(gc_tracer);
1553
1554 post_full_gc_dump(gc_timer);
1555
1556 gc_timer->register_gc_end();
1557 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1558 }
1559
1560 return true;
1561 }
1562
1563 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1564 // do_collection() will return whether it succeeded in performing
1565 // the GC. Currently, there is no facility on the
1566 // do_full_collection() API to notify the caller than the collection
1567 // did not succeed (e.g., because it was locked out by the GC
1568 // locker). So, right now, we'll ignore the return value.
1569 bool dummy = do_collection(true, /* explicit_gc */
1570 clear_all_soft_refs,
1571 0 /* word_size */);
1572 }
1573
1574 // This code is mostly copied from TenuredGeneration.
1575 void
1576 G1CollectedHeap::
1577 resize_if_necessary_after_full_collection(size_t word_size) {
1578 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1579
1580 // Include the current allocation, if any, and bytes that will be
1581 // pre-allocated to support collections, as "used".
1582 const size_t used_after_gc = used();
1583 const size_t capacity_after_gc = capacity();
1584 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1585
1586 // This is enforced in arguments.cpp.
1587 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1588 "otherwise the code below doesn't make sense");
1589
1590 // We don't have floating point command-line arguments
1591 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1592 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1593 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1594 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1595
1596 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1597 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1598
1599 // We have to be careful here as these two calculations can overflow
1600 // 32-bit size_t's.
1601 double used_after_gc_d = (double) used_after_gc;
1602 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1603 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1604
1605 // Let's make sure that they are both under the max heap size, which
1606 // by default will make them fit into a size_t.
1607 double desired_capacity_upper_bound = (double) max_heap_size;
1608 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1609 desired_capacity_upper_bound);
1610 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1611 desired_capacity_upper_bound);
1612
1613 // We can now safely turn them into size_t's.
1614 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1615 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1616
1617 // This assert only makes sense here, before we adjust them
1618 // with respect to the min and max heap size.
1619 assert(minimum_desired_capacity <= maximum_desired_capacity,
1620 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1621 "maximum_desired_capacity = "SIZE_FORMAT,
1622 minimum_desired_capacity, maximum_desired_capacity));
1623
1624 // Should not be greater than the heap max size. No need to adjust
1625 // it with respect to the heap min size as it's a lower bound (i.e.,
1626 // we'll try to make the capacity larger than it, not smaller).
1627 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1628 // Should not be less than the heap min size. No need to adjust it
1629 // with respect to the heap max size as it's an upper bound (i.e.,
1630 // we'll try to make the capacity smaller than it, not greater).
1631 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1632
1633 if (capacity_after_gc < minimum_desired_capacity) {
1634 // Don't expand unless it's significant
1635 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1636 ergo_verbose4(ErgoHeapSizing,
1637 "attempt heap expansion",
1638 ergo_format_reason("capacity lower than "
1639 "min desired capacity after Full GC")
1640 ergo_format_byte("capacity")
1641 ergo_format_byte("occupancy")
1642 ergo_format_byte_perc("min desired capacity"),
1643 capacity_after_gc, used_after_gc,
1644 minimum_desired_capacity, (double) MinHeapFreeRatio);
1645 expand(expand_bytes);
1646
1647 // No expansion, now see if we want to shrink
1648 } else if (capacity_after_gc > maximum_desired_capacity) {
1649 // Capacity too large, compute shrinking size
1650 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1651 ergo_verbose4(ErgoHeapSizing,
1652 "attempt heap shrinking",
1653 ergo_format_reason("capacity higher than "
1654 "max desired capacity after Full GC")
1655 ergo_format_byte("capacity")
1656 ergo_format_byte("occupancy")
1657 ergo_format_byte_perc("max desired capacity"),
1658 capacity_after_gc, used_after_gc,
1659 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1660 shrink(shrink_bytes);
1661 }
1662 }
1663
1664
1665 HeapWord*
1666 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1667 bool* succeeded) {
1668 assert_at_safepoint(true /* should_be_vm_thread */);
1669
1670 *succeeded = true;
1671 // Let's attempt the allocation first.
1672 HeapWord* result =
1673 attempt_allocation_at_safepoint(word_size,
1674 false /* expect_null_mutator_alloc_region */);
1675 if (result != NULL) {
1676 assert(*succeeded, "sanity");
1677 return result;
1678 }
1679
1680 // In a G1 heap, we're supposed to keep allocation from failing by
1681 // incremental pauses. Therefore, at least for now, we'll favor
1682 // expansion over collection. (This might change in the future if we can
1683 // do something smarter than full collection to satisfy a failed alloc.)
1684 result = expand_and_allocate(word_size);
1685 if (result != NULL) {
1686 assert(*succeeded, "sanity");
1687 return result;
1688 }
1689
1690 // Expansion didn't work, we'll try to do a Full GC.
1691 bool gc_succeeded = do_collection(false, /* explicit_gc */
1692 false, /* clear_all_soft_refs */
1693 word_size);
1694 if (!gc_succeeded) {
1695 *succeeded = false;
1696 return NULL;
1697 }
1698
1699 // Retry the allocation
1700 result = attempt_allocation_at_safepoint(word_size,
1701 true /* expect_null_mutator_alloc_region */);
1702 if (result != NULL) {
1703 assert(*succeeded, "sanity");
1704 return result;
1705 }
1706
1707 // Then, try a Full GC that will collect all soft references.
1708 gc_succeeded = do_collection(false, /* explicit_gc */
1709 true, /* clear_all_soft_refs */
1710 word_size);
1711 if (!gc_succeeded) {
1712 *succeeded = false;
1713 return NULL;
1714 }
1715
1716 // Retry the allocation once more
1717 result = attempt_allocation_at_safepoint(word_size,
1718 true /* expect_null_mutator_alloc_region */);
1719 if (result != NULL) {
1720 assert(*succeeded, "sanity");
1721 return result;
1722 }
1723
1724 assert(!collector_policy()->should_clear_all_soft_refs(),
1725 "Flag should have been handled and cleared prior to this point");
1726
1727 // What else? We might try synchronous finalization later. If the total
1728 // space available is large enough for the allocation, then a more
1729 // complete compaction phase than we've tried so far might be
1730 // appropriate.
1731 assert(*succeeded, "sanity");
1732 return NULL;
1733 }
1734
1735 // Attempting to expand the heap sufficiently
1736 // to support an allocation of the given "word_size". If
1737 // successful, perform the allocation and return the address of the
1738 // allocated block, or else "NULL".
1739
1740 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1741 assert_at_safepoint(true /* should_be_vm_thread */);
1742
1743 verify_region_sets_optional();
1744
1745 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1746 ergo_verbose1(ErgoHeapSizing,
1747 "attempt heap expansion",
1748 ergo_format_reason("allocation request failed")
1749 ergo_format_byte("allocation request"),
1750 word_size * HeapWordSize);
1751 if (expand(expand_bytes)) {
1752 _hrs.verify_optional();
1753 verify_region_sets_optional();
1754 return attempt_allocation_at_safepoint(word_size,
1755 false /* expect_null_mutator_alloc_region */);
1756 }
1757 return NULL;
1758 }
1759
1760 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1761 HeapWord* new_end) {
1762 assert(old_end != new_end, "don't call this otherwise");
1763 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1764
1765 // Update the committed mem region.
1766 _g1_committed.set_end(new_end);
1767 // Tell the card table about the update.
1768 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1769 // Tell the BOT about the update.
1770 _bot_shared->resize(_g1_committed.word_size());
1771 // Tell the hot card cache about the update
1772 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1773 }
1774
1775 bool G1CollectedHeap::expand(size_t expand_bytes) {
1776 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1777 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1778 HeapRegion::GrainBytes);
1779 ergo_verbose2(ErgoHeapSizing,
1780 "expand the heap",
1781 ergo_format_byte("requested expansion amount")
1782 ergo_format_byte("attempted expansion amount"),
1783 expand_bytes, aligned_expand_bytes);
1784
1785 if (_g1_storage.uncommitted_size() == 0) {
1786 ergo_verbose0(ErgoHeapSizing,
1787 "did not expand the heap",
1788 ergo_format_reason("heap already fully expanded"));
1789 return false;
1790 }
1791
1792 // First commit the memory.
1793 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1794 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1795 if (successful) {
1796 // Then propagate this update to the necessary data structures.
1797 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1798 update_committed_space(old_end, new_end);
1799
1800 FreeRegionList expansion_list("Local Expansion List");
1801 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1802 assert(mr.start() == old_end, "post-condition");
1803 // mr might be a smaller region than what was requested if
1804 // expand_by() was unable to allocate the HeapRegion instances
1805 assert(mr.end() <= new_end, "post-condition");
1806
1807 size_t actual_expand_bytes = mr.byte_size();
1808 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1809 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1810 "post-condition");
1811 if (actual_expand_bytes < aligned_expand_bytes) {
1812 // We could not expand _hrs to the desired size. In this case we
1813 // need to shrink the committed space accordingly.
1814 assert(mr.end() < new_end, "invariant");
1815
1816 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1817 // First uncommit the memory.
1818 _g1_storage.shrink_by(diff_bytes);
1819 // Then propagate this update to the necessary data structures.
1820 update_committed_space(new_end, mr.end());
1821 }
1822 _free_list.add_as_tail(&expansion_list);
1823
1824 if (_hr_printer.is_active()) {
1825 HeapWord* curr = mr.start();
1826 while (curr < mr.end()) {
1827 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1828 _hr_printer.commit(curr, curr_end);
1829 curr = curr_end;
1830 }
1831 assert(curr == mr.end(), "post-condition");
1832 }
1833 g1_policy()->record_new_heap_size(n_regions());
1834 } else {
1835 ergo_verbose0(ErgoHeapSizing,
1836 "did not expand the heap",
1837 ergo_format_reason("heap expansion operation failed"));
1838 // The expansion of the virtual storage space was unsuccessful.
1839 // Let's see if it was because we ran out of swap.
1840 if (G1ExitOnExpansionFailure &&
1841 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1842 // We had head room...
1843 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1844 }
1845 }
1846 return successful;
1847 }
1848
1849 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1850 size_t aligned_shrink_bytes =
1851 ReservedSpace::page_align_size_down(shrink_bytes);
1852 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1853 HeapRegion::GrainBytes);
1854 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1855
1856 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1857 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1858 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1859
1860 ergo_verbose3(ErgoHeapSizing,
1861 "shrink the heap",
1862 ergo_format_byte("requested shrinking amount")
1863 ergo_format_byte("aligned shrinking amount")
1864 ergo_format_byte("attempted shrinking amount"),
1865 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1866 if (num_regions_removed > 0) {
1867 _g1_storage.shrink_by(shrunk_bytes);
1868 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1869
1870 if (_hr_printer.is_active()) {
1871 HeapWord* curr = old_end;
1872 while (curr > new_end) {
1873 HeapWord* curr_end = curr;
1874 curr -= HeapRegion::GrainWords;
1875 _hr_printer.uncommit(curr, curr_end);
1876 }
1877 }
1878
1879 _expansion_regions += num_regions_removed;
1880 update_committed_space(old_end, new_end);
1881 HeapRegionRemSet::shrink_heap(n_regions());
1882 g1_policy()->record_new_heap_size(n_regions());
1883 } else {
1884 ergo_verbose0(ErgoHeapSizing,
1885 "did not shrink the heap",
1886 ergo_format_reason("heap shrinking operation failed"));
1887 }
1888 }
1889
1890 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1891 verify_region_sets_optional();
1892
1893 // We should only reach here at the end of a Full GC which means we
1894 // should not not be holding to any GC alloc regions. The method
1895 // below will make sure of that and do any remaining clean up.
1896 abandon_gc_alloc_regions();
1897
1898 // Instead of tearing down / rebuilding the free lists here, we
1899 // could instead use the remove_all_pending() method on free_list to
1900 // remove only the ones that we need to remove.
1901 tear_down_region_sets(true /* free_list_only */);
1902 shrink_helper(shrink_bytes);
1903 rebuild_region_sets(true /* free_list_only */);
1904
1905 _hrs.verify_optional();
1906 verify_region_sets_optional();
1907 }
1908
1909 // Public methods.
1910
1911 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1912 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1913 #endif // _MSC_VER
1914
1915
1916 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1917 SharedHeap(policy_),
1918 _g1_policy(policy_),
1919 _dirty_card_queue_set(false),
1920 _into_cset_dirty_card_queue_set(false),
1921 _is_alive_closure_cm(this),
1922 _is_alive_closure_stw(this),
1923 _ref_processor_cm(NULL),
1924 _ref_processor_stw(NULL),
1925 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1926 _bot_shared(NULL),
1927 _evac_failure_scan_stack(NULL),
1928 _mark_in_progress(false),
1929 _cg1r(NULL), _summary_bytes_used(0),
1930 _g1mm(NULL),
1931 _refine_cte_cl(NULL),
1932 _full_collection(false),
1933 _free_list("Master Free List"),
1934 _secondary_free_list("Secondary Free List"),
1935 _old_set("Old Set"),
1936 _humongous_set("Master Humongous Set"),
1937 _free_regions_coming(false),
1938 _young_list(new YoungList(this)),
1939 _gc_time_stamp(0),
1940 _retained_old_gc_alloc_region(NULL),
1941 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1942 _old_plab_stats(OldPLABSize, PLABWeight),
1943 _expand_heap_after_alloc_failure(true),
1944 _surviving_young_words(NULL),
1945 _old_marking_cycles_started(0),
1946 _old_marking_cycles_completed(0),
1947 _concurrent_cycle_started(false),
1948 _in_cset_fast_test(NULL),
1949 _in_cset_fast_test_base(NULL),
1950 _dirty_cards_region_list(NULL),
1951 _worker_cset_start_region(NULL),
1952 _worker_cset_start_region_time_stamp(NULL),
1953 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1954 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1955 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1956 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1957
1958 _g1h = this;
1959 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1960 vm_exit_during_initialization("Failed necessary allocation.");
1961 }
1962
1963 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1964
1965 int n_queues = MAX2((int)ParallelGCThreads, 1);
1966 _task_queues = new RefToScanQueueSet(n_queues);
1967
1968 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1969 assert(n_rem_sets > 0, "Invariant.");
1970
1971 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1972 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1973 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1974
1975 for (int i = 0; i < n_queues; i++) {
1976 RefToScanQueue* q = new RefToScanQueue();
1977 q->initialize();
1978 _task_queues->register_queue(i, q);
1979 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1980 }
1981 clear_cset_start_regions();
1982
1983 // Initialize the G1EvacuationFailureALot counters and flags.
1984 NOT_PRODUCT(reset_evacuation_should_fail();)
1985
1986 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1987 }
1988
1989 jint G1CollectedHeap::initialize() {
1990 CollectedHeap::pre_initialize();
1991 os::enable_vtime();
1992
1993 G1Log::init();
1994
1995 // Necessary to satisfy locking discipline assertions.
1996
1997 MutexLocker x(Heap_lock);
1998
1999 // We have to initialize the printer before committing the heap, as
2000 // it will be used then.
2001 _hr_printer.set_active(G1PrintHeapRegions);
2002
2003 // While there are no constraints in the GC code that HeapWordSize
2004 // be any particular value, there are multiple other areas in the
2005 // system which believe this to be true (e.g. oop->object_size in some
2006 // cases incorrectly returns the size in wordSize units rather than
2007 // HeapWordSize).
2008 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2009
2010 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2011 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2012 size_t heap_alignment = collector_policy()->heap_alignment();
2013
2014 // Ensure that the sizes are properly aligned.
2015 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2016 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2017 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2018
2019 _cg1r = new ConcurrentG1Refine(this);
2020
2021 // Reserve the maximum.
2022
2023 // When compressed oops are enabled, the preferred heap base
2024 // is calculated by subtracting the requested size from the
2025 // 32Gb boundary and using the result as the base address for
2026 // heap reservation. If the requested size is not aligned to
2027 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2028 // into the ReservedHeapSpace constructor) then the actual
2029 // base of the reserved heap may end up differing from the
2030 // address that was requested (i.e. the preferred heap base).
2031 // If this happens then we could end up using a non-optimal
2032 // compressed oops mode.
2033
2034 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2035 heap_alignment);
2036
2037 // It is important to do this in a way such that concurrent readers can't
2038 // temporarily think something is in the heap. (I've actually seen this
2039 // happen in asserts: DLD.)
2040 _reserved.set_word_size(0);
2041 _reserved.set_start((HeapWord*)heap_rs.base());
2042 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2043
2044 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2045
2046 // Create the gen rem set (and barrier set) for the entire reserved region.
2047 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2048 set_barrier_set(rem_set()->bs());
2049 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2050 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2051 return JNI_ENOMEM;
2052 }
2053
2054 // Also create a G1 rem set.
2055 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2056
2057 // Carve out the G1 part of the heap.
2058
2059 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2060 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2061 g1_rs.size()/HeapWordSize);
2062
2063 _g1_storage.initialize(g1_rs, 0);
2064 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2065 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2066 (HeapWord*) _g1_reserved.end());
2067 assert(_hrs.max_length() == _expansion_regions,
2068 err_msg("max length: %u expansion regions: %u",
2069 _hrs.max_length(), _expansion_regions));
2070
2071 // Do later initialization work for concurrent refinement.
2072 _cg1r->init();
2073
2074 // 6843694 - ensure that the maximum region index can fit
2075 // in the remembered set structures.
2076 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2077 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2078
2079 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2080 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2081 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2082 "too many cards per region");
2083
2084 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2085
2086 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2087 heap_word_size(init_byte_size));
2088
2089 _g1h = this;
2090
2091 _in_cset_fast_test_length = max_regions();
2092 _in_cset_fast_test_base =
2093 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2094
2095 // We're biasing _in_cset_fast_test to avoid subtracting the
2096 // beginning of the heap every time we want to index; basically
2097 // it's the same with what we do with the card table.
2098 _in_cset_fast_test = _in_cset_fast_test_base -
2099 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2100
2101 // Clear the _cset_fast_test bitmap in anticipation of adding
2102 // regions to the incremental collection set for the first
2103 // evacuation pause.
2104 clear_cset_fast_test();
2105
2106 // Create the ConcurrentMark data structure and thread.
2107 // (Must do this late, so that "max_regions" is defined.)
2108 _cm = new ConcurrentMark(this, heap_rs);
2109 if (_cm == NULL || !_cm->completed_initialization()) {
2110 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2111 return JNI_ENOMEM;
2112 }
2113 _cmThread = _cm->cmThread();
2114
2115 // Initialize the from_card cache structure of HeapRegionRemSet.
2116 HeapRegionRemSet::init_heap(max_regions());
2117
2118 // Now expand into the initial heap size.
2119 if (!expand(init_byte_size)) {
2120 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2121 return JNI_ENOMEM;
2122 }
2123
2124 // Perform any initialization actions delegated to the policy.
2125 g1_policy()->init();
2126
2127 _refine_cte_cl =
2128 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2129 g1_rem_set(),
2130 concurrent_g1_refine());
2131 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2132
2133 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2134 SATB_Q_FL_lock,
2135 G1SATBProcessCompletedThreshold,
2136 Shared_SATB_Q_lock);
2137
2138 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2139 DirtyCardQ_FL_lock,
2140 concurrent_g1_refine()->yellow_zone(),
2141 concurrent_g1_refine()->red_zone(),
2142 Shared_DirtyCardQ_lock);
2143
2144 if (G1DeferredRSUpdate) {
2145 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2146 DirtyCardQ_FL_lock,
2147 -1, // never trigger processing
2148 -1, // no limit on length
2149 Shared_DirtyCardQ_lock,
2150 &JavaThread::dirty_card_queue_set());
2151 }
2152
2153 // Initialize the card queue set used to hold cards containing
2154 // references into the collection set.
2155 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2156 DirtyCardQ_FL_lock,
2157 -1, // never trigger processing
2158 -1, // no limit on length
2159 Shared_DirtyCardQ_lock,
2160 &JavaThread::dirty_card_queue_set());
2161
2162 // In case we're keeping closure specialization stats, initialize those
2163 // counts and that mechanism.
2164 SpecializationStats::clear();
2165
2166 // Here we allocate the dummy full region that is required by the
2167 // G1AllocRegion class. If we don't pass an address in the reserved
2168 // space here, lots of asserts fire.
2169
2170 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2171 _g1_reserved.start());
2172 // We'll re-use the same region whether the alloc region will
2173 // require BOT updates or not and, if it doesn't, then a non-young
2174 // region will complain that it cannot support allocations without
2175 // BOT updates. So we'll tag the dummy region as young to avoid that.
2176 dummy_region->set_young();
2177 // Make sure it's full.
2178 dummy_region->set_top(dummy_region->end());
2179 G1AllocRegion::setup(this, dummy_region);
2180
2181 init_mutator_alloc_region();
2182
2183 // Do create of the monitoring and management support so that
2184 // values in the heap have been properly initialized.
2185 _g1mm = new G1MonitoringSupport(this);
2186
2187 return JNI_OK;
2188 }
2189
2190 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2191 return HeapRegion::max_region_size();
2192 }
2193
2194 void G1CollectedHeap::ref_processing_init() {
2195 // Reference processing in G1 currently works as follows:
2196 //
2197 // * There are two reference processor instances. One is
2198 // used to record and process discovered references
2199 // during concurrent marking; the other is used to
2200 // record and process references during STW pauses
2201 // (both full and incremental).
2202 // * Both ref processors need to 'span' the entire heap as
2203 // the regions in the collection set may be dotted around.
2204 //
2205 // * For the concurrent marking ref processor:
2206 // * Reference discovery is enabled at initial marking.
2207 // * Reference discovery is disabled and the discovered
2208 // references processed etc during remarking.
2209 // * Reference discovery is MT (see below).
2210 // * Reference discovery requires a barrier (see below).
2211 // * Reference processing may or may not be MT
2212 // (depending on the value of ParallelRefProcEnabled
2213 // and ParallelGCThreads).
2214 // * A full GC disables reference discovery by the CM
2215 // ref processor and abandons any entries on it's
2216 // discovered lists.
2217 //
2218 // * For the STW processor:
2219 // * Non MT discovery is enabled at the start of a full GC.
2220 // * Processing and enqueueing during a full GC is non-MT.
2221 // * During a full GC, references are processed after marking.
2222 //
2223 // * Discovery (may or may not be MT) is enabled at the start
2224 // of an incremental evacuation pause.
2225 // * References are processed near the end of a STW evacuation pause.
2226 // * For both types of GC:
2227 // * Discovery is atomic - i.e. not concurrent.
2228 // * Reference discovery will not need a barrier.
2229
2230 SharedHeap::ref_processing_init();
2231 MemRegion mr = reserved_region();
2232
2233 // Concurrent Mark ref processor
2234 _ref_processor_cm =
2235 new ReferenceProcessor(mr, // span
2236 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2237 // mt processing
2238 (int) ParallelGCThreads,
2239 // degree of mt processing
2240 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2241 // mt discovery
2242 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2243 // degree of mt discovery
2244 false,
2245 // Reference discovery is not atomic
2246 &_is_alive_closure_cm,
2247 // is alive closure
2248 // (for efficiency/performance)
2249 true);
2250 // Setting next fields of discovered
2251 // lists requires a barrier.
2252
2253 // STW ref processor
2254 _ref_processor_stw =
2255 new ReferenceProcessor(mr, // span
2256 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2257 // mt processing
2258 MAX2((int)ParallelGCThreads, 1),
2259 // degree of mt processing
2260 (ParallelGCThreads > 1),
2261 // mt discovery
2262 MAX2((int)ParallelGCThreads, 1),
2263 // degree of mt discovery
2264 true,
2265 // Reference discovery is atomic
2266 &_is_alive_closure_stw,
2267 // is alive closure
2268 // (for efficiency/performance)
2269 false);
2270 // Setting next fields of discovered
2271 // lists requires a barrier.
2272 }
2273
2274 size_t G1CollectedHeap::capacity() const {
2275 return _g1_committed.byte_size();
2276 }
2277
2278 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2279 assert(!hr->continuesHumongous(), "pre-condition");
2280 hr->reset_gc_time_stamp();
2281 if (hr->startsHumongous()) {
2282 uint first_index = hr->hrs_index() + 1;
2283 uint last_index = hr->last_hc_index();
2284 for (uint i = first_index; i < last_index; i += 1) {
2285 HeapRegion* chr = region_at(i);
2286 assert(chr->continuesHumongous(), "sanity");
2287 chr->reset_gc_time_stamp();
2288 }
2289 }
2290 }
2291
2292 #ifndef PRODUCT
2293 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2294 private:
2295 unsigned _gc_time_stamp;
2296 bool _failures;
2297
2298 public:
2299 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2300 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2301
2302 virtual bool doHeapRegion(HeapRegion* hr) {
2303 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2304 if (_gc_time_stamp != region_gc_time_stamp) {
2305 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2306 "expected %d", HR_FORMAT_PARAMS(hr),
2307 region_gc_time_stamp, _gc_time_stamp);
2308 _failures = true;
2309 }
2310 return false;
2311 }
2312
2313 bool failures() { return _failures; }
2314 };
2315
2316 void G1CollectedHeap::check_gc_time_stamps() {
2317 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2318 heap_region_iterate(&cl);
2319 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2320 }
2321 #endif // PRODUCT
2322
2323 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2324 DirtyCardQueue* into_cset_dcq,
2325 bool concurrent,
2326 int worker_i) {
2327 // Clean cards in the hot card cache
2328 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2329 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2330
2331 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2332 int n_completed_buffers = 0;
2333 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2334 n_completed_buffers++;
2335 }
2336 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2337 dcqs.clear_n_completed_buffers();
2338 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2339 }
2340
2341
2342 // Computes the sum of the storage used by the various regions.
2343
2344 size_t G1CollectedHeap::used() const {
2345 assert(Heap_lock->owner() != NULL,
2346 "Should be owned on this thread's behalf.");
2347 size_t result = _summary_bytes_used;
2348 // Read only once in case it is set to NULL concurrently
2349 HeapRegion* hr = _mutator_alloc_region.get();
2350 if (hr != NULL)
2351 result += hr->used();
2352 return result;
2353 }
2354
2355 size_t G1CollectedHeap::used_unlocked() const {
2356 size_t result = _summary_bytes_used;
2357 return result;
2358 }
2359
2360 class SumUsedClosure: public HeapRegionClosure {
2361 size_t _used;
2362 public:
2363 SumUsedClosure() : _used(0) {}
2364 bool doHeapRegion(HeapRegion* r) {
2365 if (!r->continuesHumongous()) {
2366 _used += r->used();
2367 }
2368 return false;
2369 }
2370 size_t result() { return _used; }
2371 };
2372
2373 size_t G1CollectedHeap::recalculate_used() const {
2374 SumUsedClosure blk;
2375 heap_region_iterate(&blk);
2376 return blk.result();
2377 }
2378
2379 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2380 switch (cause) {
2381 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2382 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2383 case GCCause::_g1_humongous_allocation: return true;
2384 default: return false;
2385 }
2386 }
2387
2388 #ifndef PRODUCT
2389 void G1CollectedHeap::allocate_dummy_regions() {
2390 // Let's fill up most of the region
2391 size_t word_size = HeapRegion::GrainWords - 1024;
2392 // And as a result the region we'll allocate will be humongous.
2393 guarantee(isHumongous(word_size), "sanity");
2394
2395 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2396 // Let's use the existing mechanism for the allocation
2397 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2398 if (dummy_obj != NULL) {
2399 MemRegion mr(dummy_obj, word_size);
2400 CollectedHeap::fill_with_object(mr);
2401 } else {
2402 // If we can't allocate once, we probably cannot allocate
2403 // again. Let's get out of the loop.
2404 break;
2405 }
2406 }
2407 }
2408 #endif // !PRODUCT
2409
2410 void G1CollectedHeap::increment_old_marking_cycles_started() {
2411 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2412 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2413 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2414 _old_marking_cycles_started, _old_marking_cycles_completed));
2415
2416 _old_marking_cycles_started++;
2417 }
2418
2419 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2420 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2421
2422 // We assume that if concurrent == true, then the caller is a
2423 // concurrent thread that was joined the Suspendible Thread
2424 // Set. If there's ever a cheap way to check this, we should add an
2425 // assert here.
2426
2427 // Given that this method is called at the end of a Full GC or of a
2428 // concurrent cycle, and those can be nested (i.e., a Full GC can
2429 // interrupt a concurrent cycle), the number of full collections
2430 // completed should be either one (in the case where there was no
2431 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2432 // behind the number of full collections started.
2433
2434 // This is the case for the inner caller, i.e. a Full GC.
2435 assert(concurrent ||
2436 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2437 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2438 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2439 "is inconsistent with _old_marking_cycles_completed = %u",
2440 _old_marking_cycles_started, _old_marking_cycles_completed));
2441
2442 // This is the case for the outer caller, i.e. the concurrent cycle.
2443 assert(!concurrent ||
2444 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2445 err_msg("for outer caller (concurrent cycle): "
2446 "_old_marking_cycles_started = %u "
2447 "is inconsistent with _old_marking_cycles_completed = %u",
2448 _old_marking_cycles_started, _old_marking_cycles_completed));
2449
2450 _old_marking_cycles_completed += 1;
2451
2452 // We need to clear the "in_progress" flag in the CM thread before
2453 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2454 // is set) so that if a waiter requests another System.gc() it doesn't
2455 // incorrectly see that a marking cycle is still in progress.
2456 if (concurrent) {
2457 _cmThread->clear_in_progress();
2458 }
2459
2460 // This notify_all() will ensure that a thread that called
2461 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2462 // and it's waiting for a full GC to finish will be woken up. It is
2463 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2464 FullGCCount_lock->notify_all();
2465 }
2466
2467 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2468 _concurrent_cycle_started = true;
2469 _gc_timer_cm->register_gc_start(start_time);
2470
2471 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2472 trace_heap_before_gc(_gc_tracer_cm);
2473 }
2474
2475 void G1CollectedHeap::register_concurrent_cycle_end() {
2476 if (_concurrent_cycle_started) {
2477 if (_cm->has_aborted()) {
2478 _gc_tracer_cm->report_concurrent_mode_failure();
2479 }
2480
2481 _gc_timer_cm->register_gc_end();
2482 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2483
2484 _concurrent_cycle_started = false;
2485 }
2486 }
2487
2488 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2489 if (_concurrent_cycle_started) {
2490 trace_heap_after_gc(_gc_tracer_cm);
2491 }
2492 }
2493
2494 G1YCType G1CollectedHeap::yc_type() {
2495 bool is_young = g1_policy()->gcs_are_young();
2496 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2497 bool is_during_mark = mark_in_progress();
2498
2499 if (is_initial_mark) {
2500 return InitialMark;
2501 } else if (is_during_mark) {
2502 return DuringMark;
2503 } else if (is_young) {
2504 return Normal;
2505 } else {
2506 return Mixed;
2507 }
2508 }
2509
2510 void G1CollectedHeap::collect(GCCause::Cause cause) {
2511 assert_heap_not_locked();
2512
2513 unsigned int gc_count_before;
2514 unsigned int old_marking_count_before;
2515 bool retry_gc;
2516
2517 do {
2518 retry_gc = false;
2519
2520 {
2521 MutexLocker ml(Heap_lock);
2522
2523 // Read the GC count while holding the Heap_lock
2524 gc_count_before = total_collections();
2525 old_marking_count_before = _old_marking_cycles_started;
2526 }
2527
2528 if (should_do_concurrent_full_gc(cause)) {
2529 // Schedule an initial-mark evacuation pause that will start a
2530 // concurrent cycle. We're setting word_size to 0 which means that
2531 // we are not requesting a post-GC allocation.
2532 VM_G1IncCollectionPause op(gc_count_before,
2533 0, /* word_size */
2534 true, /* should_initiate_conc_mark */
2535 g1_policy()->max_pause_time_ms(),
2536 cause);
2537
2538 VMThread::execute(&op);
2539 if (!op.pause_succeeded()) {
2540 if (old_marking_count_before == _old_marking_cycles_started) {
2541 retry_gc = op.should_retry_gc();
2542 } else {
2543 // A Full GC happened while we were trying to schedule the
2544 // initial-mark GC. No point in starting a new cycle given
2545 // that the whole heap was collected anyway.
2546 }
2547
2548 if (retry_gc) {
2549 if (GC_locker::is_active_and_needs_gc()) {
2550 GC_locker::stall_until_clear();
2551 }
2552 }
2553 }
2554 } else {
2555 if (cause == GCCause::_gc_locker
2556 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2557
2558 // Schedule a standard evacuation pause. We're setting word_size
2559 // to 0 which means that we are not requesting a post-GC allocation.
2560 VM_G1IncCollectionPause op(gc_count_before,
2561 0, /* word_size */
2562 false, /* should_initiate_conc_mark */
2563 g1_policy()->max_pause_time_ms(),
2564 cause);
2565 VMThread::execute(&op);
2566 } else {
2567 // Schedule a Full GC.
2568 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2569 VMThread::execute(&op);
2570 }
2571 }
2572 } while (retry_gc);
2573 }
2574
2575 bool G1CollectedHeap::is_in(const void* p) const {
2576 if (_g1_committed.contains(p)) {
2577 // Given that we know that p is in the committed space,
2578 // heap_region_containing_raw() should successfully
2579 // return the containing region.
2580 HeapRegion* hr = heap_region_containing_raw(p);
2581 return hr->is_in(p);
2582 } else {
2583 return false;
2584 }
2585 }
2586
2587 // Iteration functions.
2588
2589 // Iterates an OopClosure over all ref-containing fields of objects
2590 // within a HeapRegion.
2591
2592 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2593 MemRegion _mr;
2594 ExtendedOopClosure* _cl;
2595 public:
2596 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2597 : _mr(mr), _cl(cl) {}
2598 bool doHeapRegion(HeapRegion* r) {
2599 if (!r->continuesHumongous()) {
2600 r->oop_iterate(_cl);
2601 }
2602 return false;
2603 }
2604 };
2605
2606 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2607 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2608 heap_region_iterate(&blk);
2609 }
2610
2611 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2612 IterateOopClosureRegionClosure blk(mr, cl);
2613 heap_region_iterate(&blk);
2614 }
2615
2616 // Iterates an ObjectClosure over all objects within a HeapRegion.
2617
2618 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2619 ObjectClosure* _cl;
2620 public:
2621 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2622 bool doHeapRegion(HeapRegion* r) {
2623 if (! r->continuesHumongous()) {
2624 r->object_iterate(_cl);
2625 }
2626 return false;
2627 }
2628 };
2629
2630 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2631 IterateObjectClosureRegionClosure blk(cl);
2632 heap_region_iterate(&blk);
2633 }
2634
2635 // Calls a SpaceClosure on a HeapRegion.
2636
2637 class SpaceClosureRegionClosure: public HeapRegionClosure {
2638 SpaceClosure* _cl;
2639 public:
2640 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2641 bool doHeapRegion(HeapRegion* r) {
2642 _cl->do_space(r);
2643 return false;
2644 }
2645 };
2646
2647 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2648 SpaceClosureRegionClosure blk(cl);
2649 heap_region_iterate(&blk);
2650 }
2651
2652 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2653 _hrs.iterate(cl);
2654 }
2655
2656 void
2657 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2658 uint worker_id,
2659 uint no_of_par_workers,
2660 jint claim_value) {
2661 const uint regions = n_regions();
2662 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2663 no_of_par_workers :
2664 1);
2665 assert(UseDynamicNumberOfGCThreads ||
2666 no_of_par_workers == workers()->total_workers(),
2667 "Non dynamic should use fixed number of workers");
2668 // try to spread out the starting points of the workers
2669 const HeapRegion* start_hr =
2670 start_region_for_worker(worker_id, no_of_par_workers);
2671 const uint start_index = start_hr->hrs_index();
2672
2673 // each worker will actually look at all regions
2674 for (uint count = 0; count < regions; ++count) {
2675 const uint index = (start_index + count) % regions;
2676 assert(0 <= index && index < regions, "sanity");
2677 HeapRegion* r = region_at(index);
2678 // we'll ignore "continues humongous" regions (we'll process them
2679 // when we come across their corresponding "start humongous"
2680 // region) and regions already claimed
2681 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2682 continue;
2683 }
2684 // OK, try to claim it
2685 if (r->claimHeapRegion(claim_value)) {
2686 // success!
2687 assert(!r->continuesHumongous(), "sanity");
2688 if (r->startsHumongous()) {
2689 // If the region is "starts humongous" we'll iterate over its
2690 // "continues humongous" first; in fact we'll do them
2691 // first. The order is important. In on case, calling the
2692 // closure on the "starts humongous" region might de-allocate
2693 // and clear all its "continues humongous" regions and, as a
2694 // result, we might end up processing them twice. So, we'll do
2695 // them first (notice: most closures will ignore them anyway) and
2696 // then we'll do the "starts humongous" region.
2697 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2698 HeapRegion* chr = region_at(ch_index);
2699
2700 // if the region has already been claimed or it's not
2701 // "continues humongous" we're done
2702 if (chr->claim_value() == claim_value ||
2703 !chr->continuesHumongous()) {
2704 break;
2705 }
2706
2707 // No one should have claimed it directly. We can given
2708 // that we claimed its "starts humongous" region.
2709 assert(chr->claim_value() != claim_value, "sanity");
2710 assert(chr->humongous_start_region() == r, "sanity");
2711
2712 if (chr->claimHeapRegion(claim_value)) {
2713 // we should always be able to claim it; no one else should
2714 // be trying to claim this region
2715
2716 bool res2 = cl->doHeapRegion(chr);
2717 assert(!res2, "Should not abort");
2718
2719 // Right now, this holds (i.e., no closure that actually
2720 // does something with "continues humongous" regions
2721 // clears them). We might have to weaken it in the future,
2722 // but let's leave these two asserts here for extra safety.
2723 assert(chr->continuesHumongous(), "should still be the case");
2724 assert(chr->humongous_start_region() == r, "sanity");
2725 } else {
2726 guarantee(false, "we should not reach here");
2727 }
2728 }
2729 }
2730
2731 assert(!r->continuesHumongous(), "sanity");
2732 bool res = cl->doHeapRegion(r);
2733 assert(!res, "Should not abort");
2734 }
2735 }
2736 }
2737
2738 class ResetClaimValuesClosure: public HeapRegionClosure {
2739 public:
2740 bool doHeapRegion(HeapRegion* r) {
2741 r->set_claim_value(HeapRegion::InitialClaimValue);
2742 return false;
2743 }
2744 };
2745
2746 void G1CollectedHeap::reset_heap_region_claim_values() {
2747 ResetClaimValuesClosure blk;
2748 heap_region_iterate(&blk);
2749 }
2750
2751 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2752 ResetClaimValuesClosure blk;
2753 collection_set_iterate(&blk);
2754 }
2755
2756 #ifdef ASSERT
2757 // This checks whether all regions in the heap have the correct claim
2758 // value. I also piggy-backed on this a check to ensure that the
2759 // humongous_start_region() information on "continues humongous"
2760 // regions is correct.
2761
2762 class CheckClaimValuesClosure : public HeapRegionClosure {
2763 private:
2764 jint _claim_value;
2765 uint _failures;
2766 HeapRegion* _sh_region;
2767
2768 public:
2769 CheckClaimValuesClosure(jint claim_value) :
2770 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2771 bool doHeapRegion(HeapRegion* r) {
2772 if (r->claim_value() != _claim_value) {
2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2774 "claim value = %d, should be %d",
2775 HR_FORMAT_PARAMS(r),
2776 r->claim_value(), _claim_value);
2777 ++_failures;
2778 }
2779 if (!r->isHumongous()) {
2780 _sh_region = NULL;
2781 } else if (r->startsHumongous()) {
2782 _sh_region = r;
2783 } else if (r->continuesHumongous()) {
2784 if (r->humongous_start_region() != _sh_region) {
2785 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2786 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2787 HR_FORMAT_PARAMS(r),
2788 r->humongous_start_region(),
2789 _sh_region);
2790 ++_failures;
2791 }
2792 }
2793 return false;
2794 }
2795 uint failures() { return _failures; }
2796 };
2797
2798 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2799 CheckClaimValuesClosure cl(claim_value);
2800 heap_region_iterate(&cl);
2801 return cl.failures() == 0;
2802 }
2803
2804 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2805 private:
2806 jint _claim_value;
2807 uint _failures;
2808
2809 public:
2810 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2811 _claim_value(claim_value), _failures(0) { }
2812
2813 uint failures() { return _failures; }
2814
2815 bool doHeapRegion(HeapRegion* hr) {
2816 assert(hr->in_collection_set(), "how?");
2817 assert(!hr->isHumongous(), "H-region in CSet");
2818 if (hr->claim_value() != _claim_value) {
2819 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2820 "claim value = %d, should be %d",
2821 HR_FORMAT_PARAMS(hr),
2822 hr->claim_value(), _claim_value);
2823 _failures += 1;
2824 }
2825 return false;
2826 }
2827 };
2828
2829 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2830 CheckClaimValuesInCSetHRClosure cl(claim_value);
2831 collection_set_iterate(&cl);
2832 return cl.failures() == 0;
2833 }
2834 #endif // ASSERT
2835
2836 // Clear the cached CSet starting regions and (more importantly)
2837 // the time stamps. Called when we reset the GC time stamp.
2838 void G1CollectedHeap::clear_cset_start_regions() {
2839 assert(_worker_cset_start_region != NULL, "sanity");
2840 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2841
2842 int n_queues = MAX2((int)ParallelGCThreads, 1);
2843 for (int i = 0; i < n_queues; i++) {
2844 _worker_cset_start_region[i] = NULL;
2845 _worker_cset_start_region_time_stamp[i] = 0;
2846 }
2847 }
2848
2849 // Given the id of a worker, obtain or calculate a suitable
2850 // starting region for iterating over the current collection set.
2851 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2852 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2853
2854 HeapRegion* result = NULL;
2855 unsigned gc_time_stamp = get_gc_time_stamp();
2856
2857 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2858 // Cached starting region for current worker was set
2859 // during the current pause - so it's valid.
2860 // Note: the cached starting heap region may be NULL
2861 // (when the collection set is empty).
2862 result = _worker_cset_start_region[worker_i];
2863 assert(result == NULL || result->in_collection_set(), "sanity");
2864 return result;
2865 }
2866
2867 // The cached entry was not valid so let's calculate
2868 // a suitable starting heap region for this worker.
2869
2870 // We want the parallel threads to start their collection
2871 // set iteration at different collection set regions to
2872 // avoid contention.
2873 // If we have:
2874 // n collection set regions
2875 // p threads
2876 // Then thread t will start at region floor ((t * n) / p)
2877
2878 result = g1_policy()->collection_set();
2879 if (G1CollectedHeap::use_parallel_gc_threads()) {
2880 uint cs_size = g1_policy()->cset_region_length();
2881 uint active_workers = workers()->active_workers();
2882 assert(UseDynamicNumberOfGCThreads ||
2883 active_workers == workers()->total_workers(),
2884 "Unless dynamic should use total workers");
2885
2886 uint end_ind = (cs_size * worker_i) / active_workers;
2887 uint start_ind = 0;
2888
2889 if (worker_i > 0 &&
2890 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2891 // Previous workers starting region is valid
2892 // so let's iterate from there
2893 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2894 result = _worker_cset_start_region[worker_i - 1];
2895 }
2896
2897 for (uint i = start_ind; i < end_ind; i++) {
2898 result = result->next_in_collection_set();
2899 }
2900 }
2901
2902 // Note: the calculated starting heap region may be NULL
2903 // (when the collection set is empty).
2904 assert(result == NULL || result->in_collection_set(), "sanity");
2905 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2906 "should be updated only once per pause");
2907 _worker_cset_start_region[worker_i] = result;
2908 OrderAccess::storestore();
2909 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2910 return result;
2911 }
2912
2913 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2914 uint no_of_par_workers) {
2915 uint worker_num =
2916 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2917 assert(UseDynamicNumberOfGCThreads ||
2918 no_of_par_workers == workers()->total_workers(),
2919 "Non dynamic should use fixed number of workers");
2920 const uint start_index = n_regions() * worker_i / worker_num;
2921 return region_at(start_index);
2922 }
2923
2924 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2925 HeapRegion* r = g1_policy()->collection_set();
2926 while (r != NULL) {
2927 HeapRegion* next = r->next_in_collection_set();
2928 if (cl->doHeapRegion(r)) {
2929 cl->incomplete();
2930 return;
2931 }
2932 r = next;
2933 }
2934 }
2935
2936 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2937 HeapRegionClosure *cl) {
2938 if (r == NULL) {
2939 // The CSet is empty so there's nothing to do.
2940 return;
2941 }
2942
2943 assert(r->in_collection_set(),
2944 "Start region must be a member of the collection set.");
2945 HeapRegion* cur = r;
2946 while (cur != NULL) {
2947 HeapRegion* next = cur->next_in_collection_set();
2948 if (cl->doHeapRegion(cur) && false) {
2949 cl->incomplete();
2950 return;
2951 }
2952 cur = next;
2953 }
2954 cur = g1_policy()->collection_set();
2955 while (cur != r) {
2956 HeapRegion* next = cur->next_in_collection_set();
2957 if (cl->doHeapRegion(cur) && false) {
2958 cl->incomplete();
2959 return;
2960 }
2961 cur = next;
2962 }
2963 }
2964
2965 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2966 return n_regions() > 0 ? region_at(0) : NULL;
2967 }
2968
2969
2970 Space* G1CollectedHeap::space_containing(const void* addr) const {
2971 Space* res = heap_region_containing(addr);
2972 return res;
2973 }
2974
2975 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2976 Space* sp = space_containing(addr);
2977 if (sp != NULL) {
2978 return sp->block_start(addr);
2979 }
2980 return NULL;
2981 }
2982
2983 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2984 Space* sp = space_containing(addr);
2985 assert(sp != NULL, "block_size of address outside of heap");
2986 return sp->block_size(addr);
2987 }
2988
2989 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2990 Space* sp = space_containing(addr);
2991 return sp->block_is_obj(addr);
2992 }
2993
2994 bool G1CollectedHeap::supports_tlab_allocation() const {
2995 return true;
2996 }
2997
2998 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2999 return HeapRegion::GrainBytes;
3000 }
3001
3002 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3003 // Return the remaining space in the cur alloc region, but not less than
3004 // the min TLAB size.
3005
3006 // Also, this value can be at most the humongous object threshold,
3007 // since we can't allow tlabs to grow big enough to accommodate
3008 // humongous objects.
3009
3010 HeapRegion* hr = _mutator_alloc_region.get();
3011 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3012 if (hr == NULL) {
3013 return max_tlab_size;
3014 } else {
3015 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3016 }
3017 }
3018
3019 size_t G1CollectedHeap::max_capacity() const {
3020 return _g1_reserved.byte_size();
3021 }
3022
3023 jlong G1CollectedHeap::millis_since_last_gc() {
3024 // assert(false, "NYI");
3025 return 0;
3026 }
3027
3028 void G1CollectedHeap::prepare_for_verify() {
3029 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3030 ensure_parsability(false);
3031 }
3032 g1_rem_set()->prepare_for_verify();
3033 }
3034
3035 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3036 VerifyOption vo) {
3037 switch (vo) {
3038 case VerifyOption_G1UsePrevMarking:
3039 return hr->obj_allocated_since_prev_marking(obj);
3040 case VerifyOption_G1UseNextMarking:
3041 return hr->obj_allocated_since_next_marking(obj);
3042 case VerifyOption_G1UseMarkWord:
3043 return false;
3044 default:
3045 ShouldNotReachHere();
3046 }
3047 return false; // keep some compilers happy
3048 }
3049
3050 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3051 switch (vo) {
3052 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3053 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3054 case VerifyOption_G1UseMarkWord: return NULL;
3055 default: ShouldNotReachHere();
3056 }
3057 return NULL; // keep some compilers happy
3058 }
3059
3060 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3061 switch (vo) {
3062 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3063 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3064 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3065 default: ShouldNotReachHere();
3066 }
3067 return false; // keep some compilers happy
3068 }
3069
3070 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3071 switch (vo) {
3072 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3073 case VerifyOption_G1UseNextMarking: return "NTAMS";
3074 case VerifyOption_G1UseMarkWord: return "NONE";
3075 default: ShouldNotReachHere();
3076 }
3077 return NULL; // keep some compilers happy
3078 }
3079
3080 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3081 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3082 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3083 // we can change this closure to extend the simpler OopClosure.
3084 class VerifyRootsClosure: public OopsInGenClosure {
3085 private:
3086 G1CollectedHeap* _g1h;
3087 VerifyOption _vo;
3088 bool _failures;
3089 public:
3090 // _vo == UsePrevMarking -> use "prev" marking information,
3091 // _vo == UseNextMarking -> use "next" marking information,
3092 // _vo == UseMarkWord -> use mark word from object header.
3093 VerifyRootsClosure(VerifyOption vo) :
3094 _g1h(G1CollectedHeap::heap()),
3095 _vo(vo),
3096 _failures(false) { }
3097
3098 bool failures() { return _failures; }
3099
3100 template <class T> void do_oop_nv(T* p) {
3101 T heap_oop = oopDesc::load_heap_oop(p);
3102 if (!oopDesc::is_null(heap_oop)) {
3103 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3104 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3105 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3106 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3107 if (_vo == VerifyOption_G1UseMarkWord) {
3108 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3109 }
3110 obj->print_on(gclog_or_tty);
3111 _failures = true;
3112 }
3113 }
3114 }
3115
3116 void do_oop(oop* p) { do_oop_nv(p); }
3117 void do_oop(narrowOop* p) { do_oop_nv(p); }
3118 };
3119
3120 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3121 G1CollectedHeap* _g1h;
3122 OopClosure* _root_cl;
3123 nmethod* _nm;
3124 VerifyOption _vo;
3125 bool _failures;
3126
3127 template <class T> void do_oop_work(T* p) {
3128 // First verify that this root is live
3129 _root_cl->do_oop(p);
3130
3131 if (!G1VerifyHeapRegionCodeRoots) {
3132 // We're not verifying the code roots attached to heap region.
3133 return;
3134 }
3135
3136 // Don't check the code roots during marking verification in a full GC
3137 if (_vo == VerifyOption_G1UseMarkWord) {
3138 return;
3139 }
3140
3141 // Now verify that the current nmethod (which contains p) is
3142 // in the code root list of the heap region containing the
3143 // object referenced by p.
3144
3145 T heap_oop = oopDesc::load_heap_oop(p);
3146 if (!oopDesc::is_null(heap_oop)) {
3147 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3148
3149 // Now fetch the region containing the object
3150 HeapRegion* hr = _g1h->heap_region_containing(obj);
3151 HeapRegionRemSet* hrrs = hr->rem_set();
3152 // Verify that the strong code root list for this region
3153 // contains the nmethod
3154 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3155 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3156 "from nmethod "PTR_FORMAT" not in strong "
3157 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3158 p, _nm, hr->bottom(), hr->end());
3159 _failures = true;
3160 }
3161 }
3162 }
3163
3164 public:
3165 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3166 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3167
3168 void do_oop(oop* p) { do_oop_work(p); }
3169 void do_oop(narrowOop* p) { do_oop_work(p); }
3170
3171 void set_nmethod(nmethod* nm) { _nm = nm; }
3172 bool failures() { return _failures; }
3173 };
3174
3175 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3176 G1VerifyCodeRootOopClosure* _oop_cl;
3177
3178 public:
3179 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3180 _oop_cl(oop_cl) {}
3181
3182 void do_code_blob(CodeBlob* cb) {
3183 nmethod* nm = cb->as_nmethod_or_null();
3184 if (nm != NULL) {
3185 _oop_cl->set_nmethod(nm);
3186 nm->oops_do(_oop_cl);
3187 }
3188 }
3189 };
3190
3191 class YoungRefCounterClosure : public OopClosure {
3192 G1CollectedHeap* _g1h;
3193 int _count;
3194 public:
3195 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3196 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3197 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3198
3199 int count() { return _count; }
3200 void reset_count() { _count = 0; };
3201 };
3202
3203 class VerifyKlassClosure: public KlassClosure {
3204 YoungRefCounterClosure _young_ref_counter_closure;
3205 OopClosure *_oop_closure;
3206 public:
3207 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3208 void do_klass(Klass* k) {
3209 k->oops_do(_oop_closure);
3210
3211 _young_ref_counter_closure.reset_count();
3212 k->oops_do(&_young_ref_counter_closure);
3213 if (_young_ref_counter_closure.count() > 0) {
3214 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3215 }
3216 }
3217 };
3218
3219 class VerifyLivenessOopClosure: public OopClosure {
3220 G1CollectedHeap* _g1h;
3221 VerifyOption _vo;
3222 public:
3223 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3224 _g1h(g1h), _vo(vo)
3225 { }
3226 void do_oop(narrowOop *p) { do_oop_work(p); }
3227 void do_oop( oop *p) { do_oop_work(p); }
3228
3229 template <class T> void do_oop_work(T *p) {
3230 oop obj = oopDesc::load_decode_heap_oop(p);
3231 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3232 "Dead object referenced by a not dead object");
3233 }
3234 };
3235
3236 class VerifyObjsInRegionClosure: public ObjectClosure {
3237 private:
3238 G1CollectedHeap* _g1h;
3239 size_t _live_bytes;
3240 HeapRegion *_hr;
3241 VerifyOption _vo;
3242 public:
3243 // _vo == UsePrevMarking -> use "prev" marking information,
3244 // _vo == UseNextMarking -> use "next" marking information,
3245 // _vo == UseMarkWord -> use mark word from object header.
3246 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3247 : _live_bytes(0), _hr(hr), _vo(vo) {
3248 _g1h = G1CollectedHeap::heap();
3249 }
3250 void do_object(oop o) {
3251 VerifyLivenessOopClosure isLive(_g1h, _vo);
3252 assert(o != NULL, "Huh?");
3253 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3254 // If the object is alive according to the mark word,
3255 // then verify that the marking information agrees.
3256 // Note we can't verify the contra-positive of the
3257 // above: if the object is dead (according to the mark
3258 // word), it may not be marked, or may have been marked
3259 // but has since became dead, or may have been allocated
3260 // since the last marking.
3261 if (_vo == VerifyOption_G1UseMarkWord) {
3262 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3263 }
3264
3265 o->oop_iterate_no_header(&isLive);
3266 if (!_hr->obj_allocated_since_prev_marking(o)) {
3267 size_t obj_size = o->size(); // Make sure we don't overflow
3268 _live_bytes += (obj_size * HeapWordSize);
3269 }
3270 }
3271 }
3272 size_t live_bytes() { return _live_bytes; }
3273 };
3274
3275 class PrintObjsInRegionClosure : public ObjectClosure {
3276 HeapRegion *_hr;
3277 G1CollectedHeap *_g1;
3278 public:
3279 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3280 _g1 = G1CollectedHeap::heap();
3281 };
3282
3283 void do_object(oop o) {
3284 if (o != NULL) {
3285 HeapWord *start = (HeapWord *) o;
3286 size_t word_sz = o->size();
3287 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3288 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3289 (void*) o, word_sz,
3290 _g1->isMarkedPrev(o),
3291 _g1->isMarkedNext(o),
3292 _hr->obj_allocated_since_prev_marking(o));
3293 HeapWord *end = start + word_sz;
3294 HeapWord *cur;
3295 int *val;
3296 for (cur = start; cur < end; cur++) {
3297 val = (int *) cur;
3298 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3299 }
3300 }
3301 }
3302 };
3303
3304 class VerifyRegionClosure: public HeapRegionClosure {
3305 private:
3306 bool _par;
3307 VerifyOption _vo;
3308 bool _failures;
3309 public:
3310 // _vo == UsePrevMarking -> use "prev" marking information,
3311 // _vo == UseNextMarking -> use "next" marking information,
3312 // _vo == UseMarkWord -> use mark word from object header.
3313 VerifyRegionClosure(bool par, VerifyOption vo)
3314 : _par(par),
3315 _vo(vo),
3316 _failures(false) {}
3317
3318 bool failures() {
3319 return _failures;
3320 }
3321
3322 bool doHeapRegion(HeapRegion* r) {
3323 if (!r->continuesHumongous()) {
3324 bool failures = false;
3325 r->verify(_vo, &failures);
3326 if (failures) {
3327 _failures = true;
3328 } else {
3329 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3330 r->object_iterate(¬_dead_yet_cl);
3331 if (_vo != VerifyOption_G1UseNextMarking) {
3332 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3333 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3334 "max_live_bytes "SIZE_FORMAT" "
3335 "< calculated "SIZE_FORMAT,
3336 r->bottom(), r->end(),
3337 r->max_live_bytes(),
3338 not_dead_yet_cl.live_bytes());
3339 _failures = true;
3340 }
3341 } else {
3342 // When vo == UseNextMarking we cannot currently do a sanity
3343 // check on the live bytes as the calculation has not been
3344 // finalized yet.
3345 }
3346 }
3347 }
3348 return false; // stop the region iteration if we hit a failure
3349 }
3350 };
3351
3352 // This is the task used for parallel verification of the heap regions
3353
3354 class G1ParVerifyTask: public AbstractGangTask {
3355 private:
3356 G1CollectedHeap* _g1h;
3357 VerifyOption _vo;
3358 bool _failures;
3359
3360 public:
3361 // _vo == UsePrevMarking -> use "prev" marking information,
3362 // _vo == UseNextMarking -> use "next" marking information,
3363 // _vo == UseMarkWord -> use mark word from object header.
3364 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3365 AbstractGangTask("Parallel verify task"),
3366 _g1h(g1h),
3367 _vo(vo),
3368 _failures(false) { }
3369
3370 bool failures() {
3371 return _failures;
3372 }
3373
3374 void work(uint worker_id) {
3375 HandleMark hm;
3376 VerifyRegionClosure blk(true, _vo);
3377 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3378 _g1h->workers()->active_workers(),
3379 HeapRegion::ParVerifyClaimValue);
3380 if (blk.failures()) {
3381 _failures = true;
3382 }
3383 }
3384 };
3385
3386 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3387 if (SafepointSynchronize::is_at_safepoint()) {
3388 assert(Thread::current()->is_VM_thread(),
3389 "Expected to be executed serially by the VM thread at this point");
3390
3391 if (!silent) { gclog_or_tty->print("Roots "); }
3392 VerifyRootsClosure rootsCl(vo);
3393 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3394 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3395 VerifyKlassClosure klassCl(this, &rootsCl);
3396
3397 // We apply the relevant closures to all the oops in the
3398 // system dictionary, the string table and the code cache.
3399 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3400
3401 // Need cleared claim bits for the strong roots processing
3402 ClassLoaderDataGraph::clear_claimed_marks();
3403
3404 process_strong_roots(true, // activate StrongRootsScope
3405 false, // we set "is scavenging" to false,
3406 // so we don't reset the dirty cards.
3407 ScanningOption(so), // roots scanning options
3408 &rootsCl,
3409 &blobsCl,
3410 &klassCl
3411 );
3412
3413 bool failures = rootsCl.failures() || codeRootsCl.failures();
3414
3415 if (vo != VerifyOption_G1UseMarkWord) {
3416 // If we're verifying during a full GC then the region sets
3417 // will have been torn down at the start of the GC. Therefore
3418 // verifying the region sets will fail. So we only verify
3419 // the region sets when not in a full GC.
3420 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3421 verify_region_sets();
3422 }
3423
3424 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3425 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3426 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3427 "sanity check");
3428
3429 G1ParVerifyTask task(this, vo);
3430 assert(UseDynamicNumberOfGCThreads ||
3431 workers()->active_workers() == workers()->total_workers(),
3432 "If not dynamic should be using all the workers");
3433 int n_workers = workers()->active_workers();
3434 set_par_threads(n_workers);
3435 workers()->run_task(&task);
3436 set_par_threads(0);
3437 if (task.failures()) {
3438 failures = true;
3439 }
3440
3441 // Checks that the expected amount of parallel work was done.
3442 // The implication is that n_workers is > 0.
3443 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3444 "sanity check");
3445
3446 reset_heap_region_claim_values();
3447
3448 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3449 "sanity check");
3450 } else {
3451 VerifyRegionClosure blk(false, vo);
3452 heap_region_iterate(&blk);
3453 if (blk.failures()) {
3454 failures = true;
3455 }
3456 }
3457 if (!silent) gclog_or_tty->print("RemSet ");
3458 rem_set()->verify();
3459
3460 if (failures) {
3461 gclog_or_tty->print_cr("Heap:");
3462 // It helps to have the per-region information in the output to
3463 // help us track down what went wrong. This is why we call
3464 // print_extended_on() instead of print_on().
3465 print_extended_on(gclog_or_tty);
3466 gclog_or_tty->print_cr("");
3467 #ifndef PRODUCT
3468 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3469 concurrent_mark()->print_reachable("at-verification-failure",
3470 vo, false /* all */);
3471 }
3472 #endif
3473 gclog_or_tty->flush();
3474 }
3475 guarantee(!failures, "there should not have been any failures");
3476 } else {
3477 if (!silent)
3478 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3479 }
3480 }
3481
3482 void G1CollectedHeap::verify(bool silent) {
3483 verify(silent, VerifyOption_G1UsePrevMarking);
3484 }
3485
3486 double G1CollectedHeap::verify(bool guard, const char* msg) {
3487 double verify_time_ms = 0.0;
3488
3489 if (guard && total_collections() >= VerifyGCStartAt) {
3490 double verify_start = os::elapsedTime();
3491 HandleMark hm; // Discard invalid handles created during verification
3492 prepare_for_verify();
3493 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3494 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3495 }
3496
3497 return verify_time_ms;
3498 }
3499
3500 void G1CollectedHeap::verify_before_gc() {
3501 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3502 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3503 }
3504
3505 void G1CollectedHeap::verify_after_gc() {
3506 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3507 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3508 }
3509
3510 class PrintRegionClosure: public HeapRegionClosure {
3511 outputStream* _st;
3512 public:
3513 PrintRegionClosure(outputStream* st) : _st(st) {}
3514 bool doHeapRegion(HeapRegion* r) {
3515 r->print_on(_st);
3516 return false;
3517 }
3518 };
3519
3520 void G1CollectedHeap::print_on(outputStream* st) const {
3521 st->print(" %-20s", "garbage-first heap");
3522 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3523 capacity()/K, used_unlocked()/K);
3524 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3525 _g1_storage.low_boundary(),
3526 _g1_storage.high(),
3527 _g1_storage.high_boundary());
3528 st->cr();
3529 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3530 uint young_regions = _young_list->length();
3531 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3532 (size_t) young_regions * HeapRegion::GrainBytes / K);
3533 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3534 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3535 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3536 st->cr();
3537 MetaspaceAux::print_on(st);
3538 }
3539
3540 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3541 print_on(st);
3542
3543 // Print the per-region information.
3544 st->cr();
3545 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3546 "HS=humongous(starts), HC=humongous(continues), "
3547 "CS=collection set, F=free, TS=gc time stamp, "
3548 "PTAMS=previous top-at-mark-start, "
3549 "NTAMS=next top-at-mark-start)");
3550 PrintRegionClosure blk(st);
3551 heap_region_iterate(&blk);
3552 }
3553
3554 void G1CollectedHeap::print_on_error(outputStream* st) const {
3555 this->CollectedHeap::print_on_error(st);
3556
3557 if (_cm != NULL) {
3558 st->cr();
3559 _cm->print_on_error(st);
3560 }
3561 }
3562
3563 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3564 if (G1CollectedHeap::use_parallel_gc_threads()) {
3565 workers()->print_worker_threads_on(st);
3566 }
3567 _cmThread->print_on(st);
3568 st->cr();
3569 _cm->print_worker_threads_on(st);
3570 _cg1r->print_worker_threads_on(st);
3571 }
3572
3573 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3574 if (G1CollectedHeap::use_parallel_gc_threads()) {
3575 workers()->threads_do(tc);
3576 }
3577 tc->do_thread(_cmThread);
3578 _cg1r->threads_do(tc);
3579 }
3580
3581 void G1CollectedHeap::print_tracing_info() const {
3582 // We'll overload this to mean "trace GC pause statistics."
3583 if (TraceGen0Time || TraceGen1Time) {
3584 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3585 // to that.
3586 g1_policy()->print_tracing_info();
3587 }
3588 if (G1SummarizeRSetStats) {
3589 g1_rem_set()->print_summary_info();
3590 }
3591 if (G1SummarizeConcMark) {
3592 concurrent_mark()->print_summary_info();
3593 }
3594 g1_policy()->print_yg_surv_rate_info();
3595 SpecializationStats::print();
3596 }
3597
3598 #ifndef PRODUCT
3599 // Helpful for debugging RSet issues.
3600
3601 class PrintRSetsClosure : public HeapRegionClosure {
3602 private:
3603 const char* _msg;
3604 size_t _occupied_sum;
3605
3606 public:
3607 bool doHeapRegion(HeapRegion* r) {
3608 HeapRegionRemSet* hrrs = r->rem_set();
3609 size_t occupied = hrrs->occupied();
3610 _occupied_sum += occupied;
3611
3612 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3613 HR_FORMAT_PARAMS(r));
3614 if (occupied == 0) {
3615 gclog_or_tty->print_cr(" RSet is empty");
3616 } else {
3617 hrrs->print();
3618 }
3619 gclog_or_tty->print_cr("----------");
3620 return false;
3621 }
3622
3623 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3624 gclog_or_tty->cr();
3625 gclog_or_tty->print_cr("========================================");
3626 gclog_or_tty->print_cr(msg);
3627 gclog_or_tty->cr();
3628 }
3629
3630 ~PrintRSetsClosure() {
3631 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3632 gclog_or_tty->print_cr("========================================");
3633 gclog_or_tty->cr();
3634 }
3635 };
3636
3637 void G1CollectedHeap::print_cset_rsets() {
3638 PrintRSetsClosure cl("Printing CSet RSets");
3639 collection_set_iterate(&cl);
3640 }
3641
3642 void G1CollectedHeap::print_all_rsets() {
3643 PrintRSetsClosure cl("Printing All RSets");;
3644 heap_region_iterate(&cl);
3645 }
3646 #endif // PRODUCT
3647
3648 G1CollectedHeap* G1CollectedHeap::heap() {
3649 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3650 "not a garbage-first heap");
3651 return _g1h;
3652 }
3653
3654 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3655 // always_do_update_barrier = false;
3656 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3657 // Fill TLAB's and such
3658 ensure_parsability(true);
3659
3660 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3661 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3662 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3663 }
3664 }
3665
3666 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3667
3668 if (G1SummarizeRSetStats &&
3669 (G1SummarizeRSetStatsPeriod > 0) &&
3670 // we are at the end of the GC. Total collections has already been increased.
3671 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3672 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3673 }
3674
3675 // FIXME: what is this about?
3676 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3677 // is set.
3678 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3679 "derived pointer present"));
3680 // always_do_update_barrier = true;
3681
3682 // We have just completed a GC. Update the soft reference
3683 // policy with the new heap occupancy
3684 Universe::update_heap_info_at_gc();
3685 }
3686
3687 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3688 unsigned int gc_count_before,
3689 bool* succeeded,
3690 GCCause::Cause gc_cause) {
3691 assert_heap_not_locked_and_not_at_safepoint();
3692 g1_policy()->record_stop_world_start();
3693 VM_G1IncCollectionPause op(gc_count_before,
3694 word_size,
3695 false, /* should_initiate_conc_mark */
3696 g1_policy()->max_pause_time_ms(),
3697 gc_cause);
3698 VMThread::execute(&op);
3699
3700 HeapWord* result = op.result();
3701 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3702 assert(result == NULL || ret_succeeded,
3703 "the result should be NULL if the VM did not succeed");
3704 *succeeded = ret_succeeded;
3705
3706 assert_heap_not_locked();
3707 return result;
3708 }
3709
3710 void
3711 G1CollectedHeap::doConcurrentMark() {
3712 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3713 if (!_cmThread->in_progress()) {
3714 _cmThread->set_started();
3715 CGC_lock->notify();
3716 }
3717 }
3718
3719 size_t G1CollectedHeap::pending_card_num() {
3720 size_t extra_cards = 0;
3721 JavaThread *curr = Threads::first();
3722 while (curr != NULL) {
3723 DirtyCardQueue& dcq = curr->dirty_card_queue();
3724 extra_cards += dcq.size();
3725 curr = curr->next();
3726 }
3727 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3728 size_t buffer_size = dcqs.buffer_size();
3729 size_t buffer_num = dcqs.completed_buffers_num();
3730
3731 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3732 // in bytes - not the number of 'entries'. We need to convert
3733 // into a number of cards.
3734 return (buffer_size * buffer_num + extra_cards) / oopSize;
3735 }
3736
3737 size_t G1CollectedHeap::cards_scanned() {
3738 return g1_rem_set()->cardsScanned();
3739 }
3740
3741 void
3742 G1CollectedHeap::setup_surviving_young_words() {
3743 assert(_surviving_young_words == NULL, "pre-condition");
3744 uint array_length = g1_policy()->young_cset_region_length();
3745 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3746 if (_surviving_young_words == NULL) {
3747 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3748 "Not enough space for young surv words summary.");
3749 }
3750 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3751 #ifdef ASSERT
3752 for (uint i = 0; i < array_length; ++i) {
3753 assert( _surviving_young_words[i] == 0, "memset above" );
3754 }
3755 #endif // !ASSERT
3756 }
3757
3758 void
3759 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3760 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3761 uint array_length = g1_policy()->young_cset_region_length();
3762 for (uint i = 0; i < array_length; ++i) {
3763 _surviving_young_words[i] += surv_young_words[i];
3764 }
3765 }
3766
3767 void
3768 G1CollectedHeap::cleanup_surviving_young_words() {
3769 guarantee( _surviving_young_words != NULL, "pre-condition" );
3770 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3771 _surviving_young_words = NULL;
3772 }
3773
3774 #ifdef ASSERT
3775 class VerifyCSetClosure: public HeapRegionClosure {
3776 public:
3777 bool doHeapRegion(HeapRegion* hr) {
3778 // Here we check that the CSet region's RSet is ready for parallel
3779 // iteration. The fields that we'll verify are only manipulated
3780 // when the region is part of a CSet and is collected. Afterwards,
3781 // we reset these fields when we clear the region's RSet (when the
3782 // region is freed) so they are ready when the region is
3783 // re-allocated. The only exception to this is if there's an
3784 // evacuation failure and instead of freeing the region we leave
3785 // it in the heap. In that case, we reset these fields during
3786 // evacuation failure handling.
3787 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3788
3789 // Here's a good place to add any other checks we'd like to
3790 // perform on CSet regions.
3791 return false;
3792 }
3793 };
3794 #endif // ASSERT
3795
3796 #if TASKQUEUE_STATS
3797 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3798 st->print_raw_cr("GC Task Stats");
3799 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3800 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3801 }
3802
3803 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3804 print_taskqueue_stats_hdr(st);
3805
3806 TaskQueueStats totals;
3807 const int n = workers() != NULL ? workers()->total_workers() : 1;
3808 for (int i = 0; i < n; ++i) {
3809 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3810 totals += task_queue(i)->stats;
3811 }
3812 st->print_raw("tot "); totals.print(st); st->cr();
3813
3814 DEBUG_ONLY(totals.verify());
3815 }
3816
3817 void G1CollectedHeap::reset_taskqueue_stats() {
3818 const int n = workers() != NULL ? workers()->total_workers() : 1;
3819 for (int i = 0; i < n; ++i) {
3820 task_queue(i)->stats.reset();
3821 }
3822 }
3823 #endif // TASKQUEUE_STATS
3824
3825 void G1CollectedHeap::log_gc_header() {
3826 if (!G1Log::fine()) {
3827 return;
3828 }
3829
3830 gclog_or_tty->date_stamp(PrintGCDateStamps);
3831 gclog_or_tty->stamp(PrintGCTimeStamps);
3832
3833 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3834 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3835 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3836
3837 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3838 }
3839
3840 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3841 if (!G1Log::fine()) {
3842 return;
3843 }
3844
3845 if (G1Log::finer()) {
3846 if (evacuation_failed()) {
3847 gclog_or_tty->print(" (to-space exhausted)");
3848 }
3849 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3850 g1_policy()->phase_times()->note_gc_end();
3851 g1_policy()->phase_times()->print(pause_time_sec);
3852 g1_policy()->print_detailed_heap_transition();
3853 } else {
3854 if (evacuation_failed()) {
3855 gclog_or_tty->print("--");
3856 }
3857 g1_policy()->print_heap_transition();
3858 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3859 }
3860 gclog_or_tty->flush();
3861 }
3862
3863 bool
3864 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3865 assert_at_safepoint(true /* should_be_vm_thread */);
3866 guarantee(!is_gc_active(), "collection is not reentrant");
3867
3868 if (GC_locker::check_active_before_gc()) {
3869 return false;
3870 }
3871
3872 _gc_timer_stw->register_gc_start();
3873
3874 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3875
3876 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3877 ResourceMark rm;
3878
3879 print_heap_before_gc();
3880 trace_heap_before_gc(_gc_tracer_stw);
3881
3882 HRSPhaseSetter x(HRSPhaseEvacuation);
3883 verify_region_sets_optional();
3884 verify_dirty_young_regions();
3885
3886 // This call will decide whether this pause is an initial-mark
3887 // pause. If it is, during_initial_mark_pause() will return true
3888 // for the duration of this pause.
3889 g1_policy()->decide_on_conc_mark_initiation();
3890
3891 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3892 assert(!g1_policy()->during_initial_mark_pause() ||
3893 g1_policy()->gcs_are_young(), "sanity");
3894
3895 // We also do not allow mixed GCs during marking.
3896 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3897
3898 // Record whether this pause is an initial mark. When the current
3899 // thread has completed its logging output and it's safe to signal
3900 // the CM thread, the flag's value in the policy has been reset.
3901 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3902
3903 // Inner scope for scope based logging, timers, and stats collection
3904 {
3905 EvacuationInfo evacuation_info;
3906
3907 if (g1_policy()->during_initial_mark_pause()) {
3908 // We are about to start a marking cycle, so we increment the
3909 // full collection counter.
3910 increment_old_marking_cycles_started();
3911 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3912 }
3913
3914 _gc_tracer_stw->report_yc_type(yc_type());
3915
3916 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3917
3918 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3919 workers()->active_workers() : 1);
3920 double pause_start_sec = os::elapsedTime();
3921 g1_policy()->phase_times()->note_gc_start(active_workers);
3922 log_gc_header();
3923
3924 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3925 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3926
3927 // If the secondary_free_list is not empty, append it to the
3928 // free_list. No need to wait for the cleanup operation to finish;
3929 // the region allocation code will check the secondary_free_list
3930 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3931 // set, skip this step so that the region allocation code has to
3932 // get entries from the secondary_free_list.
3933 if (!G1StressConcRegionFreeing) {
3934 append_secondary_free_list_if_not_empty_with_lock();
3935 }
3936
3937 assert(check_young_list_well_formed(), "young list should be well formed");
3938 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3939 "sanity check");
3940
3941 // Don't dynamically change the number of GC threads this early. A value of
3942 // 0 is used to indicate serial work. When parallel work is done,
3943 // it will be set.
3944
3945 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3946 IsGCActiveMark x;
3947
3948 gc_prologue(false);
3949 increment_total_collections(false /* full gc */);
3950 increment_gc_time_stamp();
3951
3952 verify_before_gc();
3953
3954 COMPILER2_PRESENT(DerivedPointerTable::clear());
3955
3956 // Please see comment in g1CollectedHeap.hpp and
3957 // G1CollectedHeap::ref_processing_init() to see how
3958 // reference processing currently works in G1.
3959
3960 // Enable discovery in the STW reference processor
3961 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3962 true /*verify_no_refs*/);
3963
3964 {
3965 // We want to temporarily turn off discovery by the
3966 // CM ref processor, if necessary, and turn it back on
3967 // on again later if we do. Using a scoped
3968 // NoRefDiscovery object will do this.
3969 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3970
3971 // Forget the current alloc region (we might even choose it to be part
3972 // of the collection set!).
3973 release_mutator_alloc_region();
3974
3975 // We should call this after we retire the mutator alloc
3976 // region(s) so that all the ALLOC / RETIRE events are generated
3977 // before the start GC event.
3978 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3979
3980 // This timing is only used by the ergonomics to handle our pause target.
3981 // It is unclear why this should not include the full pause. We will
3982 // investigate this in CR 7178365.
3983 //
3984 // Preserving the old comment here if that helps the investigation:
3985 //
3986 // The elapsed time induced by the start time below deliberately elides
3987 // the possible verification above.
3988 double sample_start_time_sec = os::elapsedTime();
3989
3990 #if YOUNG_LIST_VERBOSE
3991 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3992 _young_list->print();
3993 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3994 #endif // YOUNG_LIST_VERBOSE
3995
3996 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3997
3998 double scan_wait_start = os::elapsedTime();
3999 // We have to wait until the CM threads finish scanning the
4000 // root regions as it's the only way to ensure that all the
4001 // objects on them have been correctly scanned before we start
4002 // moving them during the GC.
4003 bool waited = _cm->root_regions()->wait_until_scan_finished();
4004 double wait_time_ms = 0.0;
4005 if (waited) {
4006 double scan_wait_end = os::elapsedTime();
4007 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4008 }
4009 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4010
4011 #if YOUNG_LIST_VERBOSE
4012 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4013 _young_list->print();
4014 #endif // YOUNG_LIST_VERBOSE
4015
4016 if (g1_policy()->during_initial_mark_pause()) {
4017 concurrent_mark()->checkpointRootsInitialPre();
4018 }
4019
4020 #if YOUNG_LIST_VERBOSE
4021 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4022 _young_list->print();
4023 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4024 #endif // YOUNG_LIST_VERBOSE
4025
4026 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4027
4028 _cm->note_start_of_gc();
4029 // We should not verify the per-thread SATB buffers given that
4030 // we have not filtered them yet (we'll do so during the
4031 // GC). We also call this after finalize_cset() to
4032 // ensure that the CSet has been finalized.
4033 _cm->verify_no_cset_oops(true /* verify_stacks */,
4034 true /* verify_enqueued_buffers */,
4035 false /* verify_thread_buffers */,
4036 true /* verify_fingers */);
4037
4038 if (_hr_printer.is_active()) {
4039 HeapRegion* hr = g1_policy()->collection_set();
4040 while (hr != NULL) {
4041 G1HRPrinter::RegionType type;
4042 if (!hr->is_young()) {
4043 type = G1HRPrinter::Old;
4044 } else if (hr->is_survivor()) {
4045 type = G1HRPrinter::Survivor;
4046 } else {
4047 type = G1HRPrinter::Eden;
4048 }
4049 _hr_printer.cset(hr);
4050 hr = hr->next_in_collection_set();
4051 }
4052 }
4053
4054 #ifdef ASSERT
4055 VerifyCSetClosure cl;
4056 collection_set_iterate(&cl);
4057 #endif // ASSERT
4058
4059 setup_surviving_young_words();
4060
4061 // Initialize the GC alloc regions.
4062 init_gc_alloc_regions(evacuation_info);
4063
4064 // Actually do the work...
4065 evacuate_collection_set(evacuation_info);
4066
4067 // We do this to mainly verify the per-thread SATB buffers
4068 // (which have been filtered by now) since we didn't verify
4069 // them earlier. No point in re-checking the stacks / enqueued
4070 // buffers given that the CSet has not changed since last time
4071 // we checked.
4072 _cm->verify_no_cset_oops(false /* verify_stacks */,
4073 false /* verify_enqueued_buffers */,
4074 true /* verify_thread_buffers */,
4075 true /* verify_fingers */);
4076
4077 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4078 g1_policy()->clear_collection_set();
4079
4080 cleanup_surviving_young_words();
4081
4082 // Start a new incremental collection set for the next pause.
4083 g1_policy()->start_incremental_cset_building();
4084
4085 // Clear the _cset_fast_test bitmap in anticipation of adding
4086 // regions to the incremental collection set for the next
4087 // evacuation pause.
4088 clear_cset_fast_test();
4089
4090 _young_list->reset_sampled_info();
4091
4092 // Don't check the whole heap at this point as the
4093 // GC alloc regions from this pause have been tagged
4094 // as survivors and moved on to the survivor list.
4095 // Survivor regions will fail the !is_young() check.
4096 assert(check_young_list_empty(false /* check_heap */),
4097 "young list should be empty");
4098
4099 #if YOUNG_LIST_VERBOSE
4100 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4101 _young_list->print();
4102 #endif // YOUNG_LIST_VERBOSE
4103
4104 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4105 _young_list->first_survivor_region(),
4106 _young_list->last_survivor_region());
4107
4108 _young_list->reset_auxilary_lists();
4109
4110 if (evacuation_failed()) {
4111 _summary_bytes_used = recalculate_used();
4112 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4113 for (uint i = 0; i < n_queues; i++) {
4114 if (_evacuation_failed_info_array[i].has_failed()) {
4115 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4116 }
4117 }
4118 } else {
4119 // The "used" of the the collection set have already been subtracted
4120 // when they were freed. Add in the bytes evacuated.
4121 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4122 }
4123
4124 if (g1_policy()->during_initial_mark_pause()) {
4125 // We have to do this before we notify the CM threads that
4126 // they can start working to make sure that all the
4127 // appropriate initialization is done on the CM object.
4128 concurrent_mark()->checkpointRootsInitialPost();
4129 set_marking_started();
4130 // Note that we don't actually trigger the CM thread at
4131 // this point. We do that later when we're sure that
4132 // the current thread has completed its logging output.
4133 }
4134
4135 allocate_dummy_regions();
4136
4137 #if YOUNG_LIST_VERBOSE
4138 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4139 _young_list->print();
4140 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4141 #endif // YOUNG_LIST_VERBOSE
4142
4143 init_mutator_alloc_region();
4144
4145 {
4146 size_t expand_bytes = g1_policy()->expansion_amount();
4147 if (expand_bytes > 0) {
4148 size_t bytes_before = capacity();
4149 // No need for an ergo verbose message here,
4150 // expansion_amount() does this when it returns a value > 0.
4151 if (!expand(expand_bytes)) {
4152 // We failed to expand the heap so let's verify that
4153 // committed/uncommitted amount match the backing store
4154 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4155 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4156 }
4157 }
4158 }
4159
4160 // We redo the verification but now wrt to the new CSet which
4161 // has just got initialized after the previous CSet was freed.
4162 _cm->verify_no_cset_oops(true /* verify_stacks */,
4163 true /* verify_enqueued_buffers */,
4164 true /* verify_thread_buffers */,
4165 true /* verify_fingers */);
4166 _cm->note_end_of_gc();
4167
4168 // This timing is only used by the ergonomics to handle our pause target.
4169 // It is unclear why this should not include the full pause. We will
4170 // investigate this in CR 7178365.
4171 double sample_end_time_sec = os::elapsedTime();
4172 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4173 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4174
4175 MemoryService::track_memory_usage();
4176
4177 // In prepare_for_verify() below we'll need to scan the deferred
4178 // update buffers to bring the RSets up-to-date if
4179 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4180 // the update buffers we'll probably need to scan cards on the
4181 // regions we just allocated to (i.e., the GC alloc
4182 // regions). However, during the last GC we called
4183 // set_saved_mark() on all the GC alloc regions, so card
4184 // scanning might skip the [saved_mark_word()...top()] area of
4185 // those regions (i.e., the area we allocated objects into
4186 // during the last GC). But it shouldn't. Given that
4187 // saved_mark_word() is conditional on whether the GC time stamp
4188 // on the region is current or not, by incrementing the GC time
4189 // stamp here we invalidate all the GC time stamps on all the
4190 // regions and saved_mark_word() will simply return top() for
4191 // all the regions. This is a nicer way of ensuring this rather
4192 // than iterating over the regions and fixing them. In fact, the
4193 // GC time stamp increment here also ensures that
4194 // saved_mark_word() will return top() between pauses, i.e.,
4195 // during concurrent refinement. So we don't need the
4196 // is_gc_active() check to decided which top to use when
4197 // scanning cards (see CR 7039627).
4198 increment_gc_time_stamp();
4199
4200 verify_after_gc();
4201
4202 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4203 ref_processor_stw()->verify_no_references_recorded();
4204
4205 // CM reference discovery will be re-enabled if necessary.
4206 }
4207
4208 // We should do this after we potentially expand the heap so
4209 // that all the COMMIT events are generated before the end GC
4210 // event, and after we retire the GC alloc regions so that all
4211 // RETIRE events are generated before the end GC event.
4212 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4213
4214 if (mark_in_progress()) {
4215 concurrent_mark()->update_g1_committed();
4216 }
4217
4218 #ifdef TRACESPINNING
4219 ParallelTaskTerminator::print_termination_counts();
4220 #endif
4221
4222 gc_epilogue(false);
4223 }
4224
4225 // Print the remainder of the GC log output.
4226 log_gc_footer(os::elapsedTime() - pause_start_sec);
4227
4228 // It is not yet to safe to tell the concurrent mark to
4229 // start as we have some optional output below. We don't want the
4230 // output from the concurrent mark thread interfering with this
4231 // logging output either.
4232
4233 _hrs.verify_optional();
4234 verify_region_sets_optional();
4235
4236 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4237 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4238
4239 print_heap_after_gc();
4240 trace_heap_after_gc(_gc_tracer_stw);
4241
4242 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4243 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4244 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4245 // before any GC notifications are raised.
4246 g1mm()->update_sizes();
4247
4248 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4249 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4250 _gc_timer_stw->register_gc_end();
4251 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4252 }
4253 // It should now be safe to tell the concurrent mark thread to start
4254 // without its logging output interfering with the logging output
4255 // that came from the pause.
4256
4257 if (should_start_conc_mark) {
4258 // CAUTION: after the doConcurrentMark() call below,
4259 // the concurrent marking thread(s) could be running
4260 // concurrently with us. Make sure that anything after
4261 // this point does not assume that we are the only GC thread
4262 // running. Note: of course, the actual marking work will
4263 // not start until the safepoint itself is released in
4264 // ConcurrentGCThread::safepoint_desynchronize().
4265 doConcurrentMark();
4266 }
4267
4268 return true;
4269 }
4270
4271 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4272 {
4273 size_t gclab_word_size;
4274 switch (purpose) {
4275 case GCAllocForSurvived:
4276 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4277 break;
4278 case GCAllocForTenured:
4279 gclab_word_size = _old_plab_stats.desired_plab_sz();
4280 break;
4281 default:
4282 assert(false, "unknown GCAllocPurpose");
4283 gclab_word_size = _old_plab_stats.desired_plab_sz();
4284 break;
4285 }
4286
4287 // Prevent humongous PLAB sizes for two reasons:
4288 // * PLABs are allocated using a similar paths as oops, but should
4289 // never be in a humongous region
4290 // * Allowing humongous PLABs needlessly churns the region free lists
4291 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4292 }
4293
4294 void G1CollectedHeap::init_mutator_alloc_region() {
4295 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4296 _mutator_alloc_region.init();
4297 }
4298
4299 void G1CollectedHeap::release_mutator_alloc_region() {
4300 _mutator_alloc_region.release();
4301 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4302 }
4303
4304 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4305 assert_at_safepoint(true /* should_be_vm_thread */);
4306
4307 _survivor_gc_alloc_region.init();
4308 _old_gc_alloc_region.init();
4309 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4310 _retained_old_gc_alloc_region = NULL;
4311
4312 // We will discard the current GC alloc region if:
4313 // a) it's in the collection set (it can happen!),
4314 // b) it's already full (no point in using it),
4315 // c) it's empty (this means that it was emptied during
4316 // a cleanup and it should be on the free list now), or
4317 // d) it's humongous (this means that it was emptied
4318 // during a cleanup and was added to the free list, but
4319 // has been subsequently used to allocate a humongous
4320 // object that may be less than the region size).
4321 if (retained_region != NULL &&
4322 !retained_region->in_collection_set() &&
4323 !(retained_region->top() == retained_region->end()) &&
4324 !retained_region->is_empty() &&
4325 !retained_region->isHumongous()) {
4326 retained_region->set_saved_mark();
4327 // The retained region was added to the old region set when it was
4328 // retired. We have to remove it now, since we don't allow regions
4329 // we allocate to in the region sets. We'll re-add it later, when
4330 // it's retired again.
4331 _old_set.remove(retained_region);
4332 bool during_im = g1_policy()->during_initial_mark_pause();
4333 retained_region->note_start_of_copying(during_im);
4334 _old_gc_alloc_region.set(retained_region);
4335 _hr_printer.reuse(retained_region);
4336 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4337 }
4338 }
4339
4340 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4341 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4342 _old_gc_alloc_region.count());
4343 _survivor_gc_alloc_region.release();
4344 // If we have an old GC alloc region to release, we'll save it in
4345 // _retained_old_gc_alloc_region. If we don't
4346 // _retained_old_gc_alloc_region will become NULL. This is what we
4347 // want either way so no reason to check explicitly for either
4348 // condition.
4349 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4350
4351 if (ResizePLAB) {
4352 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4353 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4354 }
4355 }
4356
4357 void G1CollectedHeap::abandon_gc_alloc_regions() {
4358 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4359 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4360 _retained_old_gc_alloc_region = NULL;
4361 }
4362
4363 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4364 _drain_in_progress = false;
4365 set_evac_failure_closure(cl);
4366 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4367 }
4368
4369 void G1CollectedHeap::finalize_for_evac_failure() {
4370 assert(_evac_failure_scan_stack != NULL &&
4371 _evac_failure_scan_stack->length() == 0,
4372 "Postcondition");
4373 assert(!_drain_in_progress, "Postcondition");
4374 delete _evac_failure_scan_stack;
4375 _evac_failure_scan_stack = NULL;
4376 }
4377
4378 void G1CollectedHeap::remove_self_forwarding_pointers() {
4379 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4380
4381 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4382
4383 if (G1CollectedHeap::use_parallel_gc_threads()) {
4384 set_par_threads();
4385 workers()->run_task(&rsfp_task);
4386 set_par_threads(0);
4387 } else {
4388 rsfp_task.work(0);
4389 }
4390
4391 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4392
4393 // Reset the claim values in the regions in the collection set.
4394 reset_cset_heap_region_claim_values();
4395
4396 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4397
4398 // Now restore saved marks, if any.
4399 assert(_objs_with_preserved_marks.size() ==
4400 _preserved_marks_of_objs.size(), "Both or none.");
4401 while (!_objs_with_preserved_marks.is_empty()) {
4402 oop obj = _objs_with_preserved_marks.pop();
4403 markOop m = _preserved_marks_of_objs.pop();
4404 obj->set_mark(m);
4405 }
4406 _objs_with_preserved_marks.clear(true);
4407 _preserved_marks_of_objs.clear(true);
4408 }
4409
4410 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4411 _evac_failure_scan_stack->push(obj);
4412 }
4413
4414 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4415 assert(_evac_failure_scan_stack != NULL, "precondition");
4416
4417 while (_evac_failure_scan_stack->length() > 0) {
4418 oop obj = _evac_failure_scan_stack->pop();
4419 _evac_failure_closure->set_region(heap_region_containing(obj));
4420 obj->oop_iterate_backwards(_evac_failure_closure);
4421 }
4422 }
4423
4424 oop
4425 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4426 oop old) {
4427 assert(obj_in_cs(old),
4428 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4429 (HeapWord*) old));
4430 markOop m = old->mark();
4431 oop forward_ptr = old->forward_to_atomic(old);
4432 if (forward_ptr == NULL) {
4433 // Forward-to-self succeeded.
4434 assert(_par_scan_state != NULL, "par scan state");
4435 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4436 uint queue_num = _par_scan_state->queue_num();
4437
4438 _evacuation_failed = true;
4439 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4440 if (_evac_failure_closure != cl) {
4441 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4442 assert(!_drain_in_progress,
4443 "Should only be true while someone holds the lock.");
4444 // Set the global evac-failure closure to the current thread's.
4445 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4446 set_evac_failure_closure(cl);
4447 // Now do the common part.
4448 handle_evacuation_failure_common(old, m);
4449 // Reset to NULL.
4450 set_evac_failure_closure(NULL);
4451 } else {
4452 // The lock is already held, and this is recursive.
4453 assert(_drain_in_progress, "This should only be the recursive case.");
4454 handle_evacuation_failure_common(old, m);
4455 }
4456 return old;
4457 } else {
4458 // Forward-to-self failed. Either someone else managed to allocate
4459 // space for this object (old != forward_ptr) or they beat us in
4460 // self-forwarding it (old == forward_ptr).
4461 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4462 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4463 "should not be in the CSet",
4464 (HeapWord*) old, (HeapWord*) forward_ptr));
4465 return forward_ptr;
4466 }
4467 }
4468
4469 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4470 preserve_mark_if_necessary(old, m);
4471
4472 HeapRegion* r = heap_region_containing(old);
4473 if (!r->evacuation_failed()) {
4474 r->set_evacuation_failed(true);
4475 _hr_printer.evac_failure(r);
4476 }
4477
4478 push_on_evac_failure_scan_stack(old);
4479
4480 if (!_drain_in_progress) {
4481 // prevent recursion in copy_to_survivor_space()
4482 _drain_in_progress = true;
4483 drain_evac_failure_scan_stack();
4484 _drain_in_progress = false;
4485 }
4486 }
4487
4488 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4489 assert(evacuation_failed(), "Oversaving!");
4490 // We want to call the "for_promotion_failure" version only in the
4491 // case of a promotion failure.
4492 if (m->must_be_preserved_for_promotion_failure(obj)) {
4493 _objs_with_preserved_marks.push(obj);
4494 _preserved_marks_of_objs.push(m);
4495 }
4496 }
4497
4498 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4499 size_t word_size) {
4500 if (purpose == GCAllocForSurvived) {
4501 HeapWord* result = survivor_attempt_allocation(word_size);
4502 if (result != NULL) {
4503 return result;
4504 } else {
4505 // Let's try to allocate in the old gen in case we can fit the
4506 // object there.
4507 return old_attempt_allocation(word_size);
4508 }
4509 } else {
4510 assert(purpose == GCAllocForTenured, "sanity");
4511 HeapWord* result = old_attempt_allocation(word_size);
4512 if (result != NULL) {
4513 return result;
4514 } else {
4515 // Let's try to allocate in the survivors in case we can fit the
4516 // object there.
4517 return survivor_attempt_allocation(word_size);
4518 }
4519 }
4520
4521 ShouldNotReachHere();
4522 // Trying to keep some compilers happy.
4523 return NULL;
4524 }
4525
4526 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4527 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4528
4529 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4530 : _g1h(g1h),
4531 _refs(g1h->task_queue(queue_num)),
4532 _dcq(&g1h->dirty_card_queue_set()),
4533 _ct_bs(g1h->g1_barrier_set()),
4534 _g1_rem(g1h->g1_rem_set()),
4535 _hash_seed(17), _queue_num(queue_num),
4536 _term_attempts(0),
4537 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4538 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4539 _age_table(false),
4540 _strong_roots_time(0), _term_time(0),
4541 _alloc_buffer_waste(0), _undo_waste(0) {
4542 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4543 // we "sacrifice" entry 0 to keep track of surviving bytes for
4544 // non-young regions (where the age is -1)
4545 // We also add a few elements at the beginning and at the end in
4546 // an attempt to eliminate cache contention
4547 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4548 uint array_length = PADDING_ELEM_NUM +
4549 real_length +
4550 PADDING_ELEM_NUM;
4551 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4552 if (_surviving_young_words_base == NULL)
4553 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4554 "Not enough space for young surv histo.");
4555 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4556 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4557
4558 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4559 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4560
4561 _start = os::elapsedTime();
4562 }
4563
4564 void
4565 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4566 {
4567 st->print_raw_cr("GC Termination Stats");
4568 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4569 " ------waste (KiB)------");
4570 st->print_raw_cr("thr ms ms % ms % attempts"
4571 " total alloc undo");
4572 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4573 " ------- ------- -------");
4574 }
4575
4576 void
4577 G1ParScanThreadState::print_termination_stats(int i,
4578 outputStream* const st) const
4579 {
4580 const double elapsed_ms = elapsed_time() * 1000.0;
4581 const double s_roots_ms = strong_roots_time() * 1000.0;
4582 const double term_ms = term_time() * 1000.0;
4583 st->print_cr("%3d %9.2f %9.2f %6.2f "
4584 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4585 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4586 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4587 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4588 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4589 alloc_buffer_waste() * HeapWordSize / K,
4590 undo_waste() * HeapWordSize / K);
4591 }
4592
4593 #ifdef ASSERT
4594 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4595 assert(ref != NULL, "invariant");
4596 assert(UseCompressedOops, "sanity");
4597 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4598 oop p = oopDesc::load_decode_heap_oop(ref);
4599 assert(_g1h->is_in_g1_reserved(p),
4600 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4601 return true;
4602 }
4603
4604 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4605 assert(ref != NULL, "invariant");
4606 if (has_partial_array_mask(ref)) {
4607 // Must be in the collection set--it's already been copied.
4608 oop p = clear_partial_array_mask(ref);
4609 assert(_g1h->obj_in_cs(p),
4610 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4611 } else {
4612 oop p = oopDesc::load_decode_heap_oop(ref);
4613 assert(_g1h->is_in_g1_reserved(p),
4614 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4615 }
4616 return true;
4617 }
4618
4619 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4620 if (ref.is_narrow()) {
4621 return verify_ref((narrowOop*) ref);
4622 } else {
4623 return verify_ref((oop*) ref);
4624 }
4625 }
4626 #endif // ASSERT
4627
4628 void G1ParScanThreadState::trim_queue() {
4629 assert(_evac_cl != NULL, "not set");
4630 assert(_evac_failure_cl != NULL, "not set");
4631 assert(_partial_scan_cl != NULL, "not set");
4632
4633 StarTask ref;
4634 do {
4635 // Drain the overflow stack first, so other threads can steal.
4636 while (refs()->pop_overflow(ref)) {
4637 deal_with_reference(ref);
4638 }
4639
4640 while (refs()->pop_local(ref)) {
4641 deal_with_reference(ref);
4642 }
4643 } while (!refs()->is_empty());
4644 }
4645
4646 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4647 G1ParScanThreadState* par_scan_state) :
4648 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4649 _par_scan_state(par_scan_state),
4650 _worker_id(par_scan_state->queue_num()),
4651 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4652 _mark_in_progress(_g1->mark_in_progress()) { }
4653
4654 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4655 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4656 #ifdef ASSERT
4657 HeapRegion* hr = _g1->heap_region_containing(obj);
4658 assert(hr != NULL, "sanity");
4659 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4660 #endif // ASSERT
4661
4662 // We know that the object is not moving so it's safe to read its size.
4663 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4664 }
4665
4666 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4667 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4668 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4669 #ifdef ASSERT
4670 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4671 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4672 assert(from_obj != to_obj, "should not be self-forwarded");
4673
4674 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4675 assert(from_hr != NULL, "sanity");
4676 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4677
4678 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4679 assert(to_hr != NULL, "sanity");
4680 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4681 #endif // ASSERT
4682
4683 // The object might be in the process of being copied by another
4684 // worker so we cannot trust that its to-space image is
4685 // well-formed. So we have to read its size from its from-space
4686 // image which we know should not be changing.
4687 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4688 }
4689
4690 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4691 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4692 ::copy_to_survivor_space(oop old) {
4693 size_t word_sz = old->size();
4694 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4695 // +1 to make the -1 indexes valid...
4696 int young_index = from_region->young_index_in_cset()+1;
4697 assert( (from_region->is_young() && young_index > 0) ||
4698 (!from_region->is_young() && young_index == 0), "invariant" );
4699 G1CollectorPolicy* g1p = _g1->g1_policy();
4700 markOop m = old->mark();
4701 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4702 : m->age();
4703 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4704 word_sz);
4705 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4706 #ifndef PRODUCT
4707 // Should this evacuation fail?
4708 if (_g1->evacuation_should_fail()) {
4709 if (obj_ptr != NULL) {
4710 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4711 obj_ptr = NULL;
4712 }
4713 }
4714 #endif // !PRODUCT
4715
4716 if (obj_ptr == NULL) {
4717 // This will either forward-to-self, or detect that someone else has
4718 // installed a forwarding pointer.
4719 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4720 }
4721
4722 oop obj = oop(obj_ptr);
4723
4724 // We're going to allocate linearly, so might as well prefetch ahead.
4725 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4726
4727 oop forward_ptr = old->forward_to_atomic(obj);
4728 if (forward_ptr == NULL) {
4729 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4730 if (g1p->track_object_age(alloc_purpose)) {
4731 // We could simply do obj->incr_age(). However, this causes a
4732 // performance issue. obj->incr_age() will first check whether
4733 // the object has a displaced mark by checking its mark word;
4734 // getting the mark word from the new location of the object
4735 // stalls. So, given that we already have the mark word and we
4736 // are about to install it anyway, it's better to increase the
4737 // age on the mark word, when the object does not have a
4738 // displaced mark word. We're not expecting many objects to have
4739 // a displaced marked word, so that case is not optimized
4740 // further (it could be...) and we simply call obj->incr_age().
4741
4742 if (m->has_displaced_mark_helper()) {
4743 // in this case, we have to install the mark word first,
4744 // otherwise obj looks to be forwarded (the old mark word,
4745 // which contains the forward pointer, was copied)
4746 obj->set_mark(m);
4747 obj->incr_age();
4748 } else {
4749 m = m->incr_age();
4750 obj->set_mark(m);
4751 }
4752 _par_scan_state->age_table()->add(obj, word_sz);
4753 } else {
4754 obj->set_mark(m);
4755 }
4756
4757 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4758 surv_young_words[young_index] += word_sz;
4759
4760 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4761 // We keep track of the next start index in the length field of
4762 // the to-space object. The actual length can be found in the
4763 // length field of the from-space object.
4764 arrayOop(obj)->set_length(0);
4765 oop* old_p = set_partial_array_mask(old);
4766 _par_scan_state->push_on_queue(old_p);
4767 } else {
4768 // No point in using the slower heap_region_containing() method,
4769 // given that we know obj is in the heap.
4770 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4771 obj->oop_iterate_backwards(&_scanner);
4772 }
4773 } else {
4774 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4775 obj = forward_ptr;
4776 }
4777 return obj;
4778 }
4779
4780 template <class T>
4781 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4782 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4783 _scanned_klass->record_modified_oops();
4784 }
4785 }
4786
4787 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4788 template <class T>
4789 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4790 ::do_oop_work(T* p) {
4791 oop obj = oopDesc::load_decode_heap_oop(p);
4792 assert(barrier != G1BarrierRS || obj != NULL,
4793 "Precondition: G1BarrierRS implies obj is non-NULL");
4794
4795 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4796
4797 // here the null check is implicit in the cset_fast_test() test
4798 if (_g1->in_cset_fast_test(obj)) {
4799 oop forwardee;
4800 if (obj->is_forwarded()) {
4801 forwardee = obj->forwardee();
4802 } else {
4803 forwardee = copy_to_survivor_space(obj);
4804 }
4805 assert(forwardee != NULL, "forwardee should not be NULL");
4806 oopDesc::encode_store_heap_oop(p, forwardee);
4807 if (do_mark_object && forwardee != obj) {
4808 // If the object is self-forwarded we don't need to explicitly
4809 // mark it, the evacuation failure protocol will do so.
4810 mark_forwarded_object(obj, forwardee);
4811 }
4812
4813 // When scanning the RS, we only care about objs in CS.
4814 if (barrier == G1BarrierRS) {
4815 _par_scan_state->update_rs(_from, p, _worker_id);
4816 } else if (barrier == G1BarrierKlass) {
4817 do_klass_barrier(p, forwardee);
4818 }
4819 } else {
4820 // The object is not in collection set. If we're a root scanning
4821 // closure during an initial mark pause (i.e. do_mark_object will
4822 // be true) then attempt to mark the object.
4823 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4824 mark_object(obj);
4825 }
4826 }
4827
4828 if (barrier == G1BarrierEvac && obj != NULL) {
4829 _par_scan_state->update_rs(_from, p, _worker_id);
4830 }
4831
4832 if (do_gen_barrier && obj != NULL) {
4833 par_do_barrier(p);
4834 }
4835 }
4836
4837 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4838 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4839
4840 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4841 assert(has_partial_array_mask(p), "invariant");
4842 oop from_obj = clear_partial_array_mask(p);
4843
4844 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4845 assert(from_obj->is_objArray(), "must be obj array");
4846 objArrayOop from_obj_array = objArrayOop(from_obj);
4847 // The from-space object contains the real length.
4848 int length = from_obj_array->length();
4849
4850 assert(from_obj->is_forwarded(), "must be forwarded");
4851 oop to_obj = from_obj->forwardee();
4852 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4853 objArrayOop to_obj_array = objArrayOop(to_obj);
4854 // We keep track of the next start index in the length field of the
4855 // to-space object.
4856 int next_index = to_obj_array->length();
4857 assert(0 <= next_index && next_index < length,
4858 err_msg("invariant, next index: %d, length: %d", next_index, length));
4859
4860 int start = next_index;
4861 int end = length;
4862 int remainder = end - start;
4863 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4864 if (remainder > 2 * ParGCArrayScanChunk) {
4865 end = start + ParGCArrayScanChunk;
4866 to_obj_array->set_length(end);
4867 // Push the remainder before we process the range in case another
4868 // worker has run out of things to do and can steal it.
4869 oop* from_obj_p = set_partial_array_mask(from_obj);
4870 _par_scan_state->push_on_queue(from_obj_p);
4871 } else {
4872 assert(length == end, "sanity");
4873 // We'll process the final range for this object. Restore the length
4874 // so that the heap remains parsable in case of evacuation failure.
4875 to_obj_array->set_length(end);
4876 }
4877 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4878 // Process indexes [start,end). It will also process the header
4879 // along with the first chunk (i.e., the chunk with start == 0).
4880 // Note that at this point the length field of to_obj_array is not
4881 // correct given that we are using it to keep track of the next
4882 // start index. oop_iterate_range() (thankfully!) ignores the length
4883 // field and only relies on the start / end parameters. It does
4884 // however return the size of the object which will be incorrect. So
4885 // we have to ignore it even if we wanted to use it.
4886 to_obj_array->oop_iterate_range(&_scanner, start, end);
4887 }
4888
4889 class G1ParEvacuateFollowersClosure : public VoidClosure {
4890 protected:
4891 G1CollectedHeap* _g1h;
4892 G1ParScanThreadState* _par_scan_state;
4893 RefToScanQueueSet* _queues;
4894 ParallelTaskTerminator* _terminator;
4895
4896 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4897 RefToScanQueueSet* queues() { return _queues; }
4898 ParallelTaskTerminator* terminator() { return _terminator; }
4899
4900 public:
4901 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4902 G1ParScanThreadState* par_scan_state,
4903 RefToScanQueueSet* queues,
4904 ParallelTaskTerminator* terminator)
4905 : _g1h(g1h), _par_scan_state(par_scan_state),
4906 _queues(queues), _terminator(terminator) {}
4907
4908 void do_void();
4909
4910 private:
4911 inline bool offer_termination();
4912 };
4913
4914 bool G1ParEvacuateFollowersClosure::offer_termination() {
4915 G1ParScanThreadState* const pss = par_scan_state();
4916 pss->start_term_time();
4917 const bool res = terminator()->offer_termination();
4918 pss->end_term_time();
4919 return res;
4920 }
4921
4922 void G1ParEvacuateFollowersClosure::do_void() {
4923 StarTask stolen_task;
4924 G1ParScanThreadState* const pss = par_scan_state();
4925 pss->trim_queue();
4926
4927 do {
4928 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4929 assert(pss->verify_task(stolen_task), "sanity");
4930 if (stolen_task.is_narrow()) {
4931 pss->deal_with_reference((narrowOop*) stolen_task);
4932 } else {
4933 pss->deal_with_reference((oop*) stolen_task);
4934 }
4935
4936 // We've just processed a reference and we might have made
4937 // available new entries on the queues. So we have to make sure
4938 // we drain the queues as necessary.
4939 pss->trim_queue();
4940 }
4941 } while (!offer_termination());
4942
4943 pss->retire_alloc_buffers();
4944 }
4945
4946 class G1KlassScanClosure : public KlassClosure {
4947 G1ParCopyHelper* _closure;
4948 bool _process_only_dirty;
4949 int _count;
4950 public:
4951 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4952 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4953 void do_klass(Klass* klass) {
4954 // If the klass has not been dirtied we know that there's
4955 // no references into the young gen and we can skip it.
4956 if (!_process_only_dirty || klass->has_modified_oops()) {
4957 // Clean the klass since we're going to scavenge all the metadata.
4958 klass->clear_modified_oops();
4959
4960 // Tell the closure that this klass is the Klass to scavenge
4961 // and is the one to dirty if oops are left pointing into the young gen.
4962 _closure->set_scanned_klass(klass);
4963
4964 klass->oops_do(_closure);
4965
4966 _closure->set_scanned_klass(NULL);
4967 }
4968 _count++;
4969 }
4970 };
4971
4972 class G1ParTask : public AbstractGangTask {
4973 protected:
4974 G1CollectedHeap* _g1h;
4975 RefToScanQueueSet *_queues;
4976 ParallelTaskTerminator _terminator;
4977 uint _n_workers;
4978
4979 Mutex _stats_lock;
4980 Mutex* stats_lock() { return &_stats_lock; }
4981
4982 size_t getNCards() {
4983 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4984 / G1BlockOffsetSharedArray::N_bytes;
4985 }
4986
4987 public:
4988 G1ParTask(G1CollectedHeap* g1h,
4989 RefToScanQueueSet *task_queues)
4990 : AbstractGangTask("G1 collection"),
4991 _g1h(g1h),
4992 _queues(task_queues),
4993 _terminator(0, _queues),
4994 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4995 {}
4996
4997 RefToScanQueueSet* queues() { return _queues; }
4998
4999 RefToScanQueue *work_queue(int i) {
5000 return queues()->queue(i);
5001 }
5002
5003 ParallelTaskTerminator* terminator() { return &_terminator; }
5004
5005 virtual void set_for_termination(int active_workers) {
5006 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5007 // in the young space (_par_seq_tasks) in the G1 heap
5008 // for SequentialSubTasksDone.
5009 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5010 // both of which need setting by set_n_termination().
5011 _g1h->SharedHeap::set_n_termination(active_workers);
5012 _g1h->set_n_termination(active_workers);
5013 terminator()->reset_for_reuse(active_workers);
5014 _n_workers = active_workers;
5015 }
5016
5017 void work(uint worker_id) {
5018 if (worker_id >= _n_workers) return; // no work needed this round
5019
5020 double start_time_ms = os::elapsedTime() * 1000.0;
5021 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5022
5023 {
5024 ResourceMark rm;
5025 HandleMark hm;
5026
5027 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5028
5029 G1ParScanThreadState pss(_g1h, worker_id);
5030 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5031 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5032 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5033
5034 pss.set_evac_closure(&scan_evac_cl);
5035 pss.set_evac_failure_closure(&evac_failure_cl);
5036 pss.set_partial_scan_closure(&partial_scan_cl);
5037
5038 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5039 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5040
5041 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5042 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5043
5044 bool only_young = _g1h->g1_policy()->gcs_are_young();
5045 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5046 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5047
5048 OopClosure* scan_root_cl = &only_scan_root_cl;
5049 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5050
5051 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5052 // We also need to mark copied objects.
5053 scan_root_cl = &scan_mark_root_cl;
5054 scan_klasses_cl = &scan_mark_klasses_cl_s;
5055 }
5056
5057 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5058
5059 // Don't scan the scavengable methods in the code cache as part
5060 // of strong root scanning. The code roots that point into a
5061 // region in the collection set are scanned when we scan the
5062 // region's RSet.
5063 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5064
5065 pss.start_strong_roots();
5066 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5067 SharedHeap::ScanningOption(so),
5068 scan_root_cl,
5069 &push_heap_rs_cl,
5070 scan_klasses_cl,
5071 worker_id);
5072 pss.end_strong_roots();
5073
5074 {
5075 double start = os::elapsedTime();
5076 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5077 evac.do_void();
5078 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5079 double term_ms = pss.term_time()*1000.0;
5080 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5081 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5082 }
5083 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5084 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5085
5086 if (ParallelGCVerbose) {
5087 MutexLocker x(stats_lock());
5088 pss.print_termination_stats(worker_id);
5089 }
5090
5091 assert(pss.refs()->is_empty(), "should be empty");
5092
5093 // Close the inner scope so that the ResourceMark and HandleMark
5094 // destructors are executed here and are included as part of the
5095 // "GC Worker Time".
5096 }
5097
5098 double end_time_ms = os::elapsedTime() * 1000.0;
5099 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5100 }
5101 };
5102
5103 // *** Common G1 Evacuation Stuff
5104
5105 // This method is run in a GC worker.
5106
5107 void
5108 G1CollectedHeap::
5109 g1_process_strong_roots(bool is_scavenging,
5110 ScanningOption so,
5111 OopClosure* scan_non_heap_roots,
5112 OopsInHeapRegionClosure* scan_rs,
5113 G1KlassScanClosure* scan_klasses,
5114 int worker_i) {
5115
5116 // First scan the strong roots
5117 double ext_roots_start = os::elapsedTime();
5118 double closure_app_time_sec = 0.0;
5119
5120 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5121
5122 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5123 // Walk the code cache/strong code roots w/o buffering, because StarTask
5124 // cannot handle unaligned oop locations.
5125 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5126
5127 process_strong_roots(false, // no scoping; this is parallel code
5128 is_scavenging, so,
5129 &buf_scan_non_heap_roots,
5130 &eager_scan_code_roots,
5131 scan_klasses
5132 );
5133
5134 // Now the CM ref_processor roots.
5135 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5136 // We need to treat the discovered reference lists of the
5137 // concurrent mark ref processor as roots and keep entries
5138 // (which are added by the marking threads) on them live
5139 // until they can be processed at the end of marking.
5140 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5141 }
5142
5143 // Finish up any enqueued closure apps (attributed as object copy time).
5144 buf_scan_non_heap_roots.done();
5145
5146 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5147
5148 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5149
5150 double ext_root_time_ms =
5151 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5152
5153 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5154
5155 // During conc marking we have to filter the per-thread SATB buffers
5156 // to make sure we remove any oops into the CSet (which will show up
5157 // as implicitly live).
5158 double satb_filtering_ms = 0.0;
5159 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5160 if (mark_in_progress()) {
5161 double satb_filter_start = os::elapsedTime();
5162
5163 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5164
5165 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5166 }
5167 }
5168 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5169
5170 // If this is an initial mark pause, and we're not scanning
5171 // the entire code cache, we need to mark the oops in the
5172 // strong code root lists for the regions that are not in
5173 // the collection set.
5174 // Note all threads participate in this set of root tasks.
5175 double mark_strong_code_roots_ms = 0.0;
5176 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5177 double mark_strong_roots_start = os::elapsedTime();
5178 mark_strong_code_roots(worker_i);
5179 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5180 }
5181 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5182
5183 // Now scan the complement of the collection set.
5184 if (scan_rs != NULL) {
5185 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5186 }
5187 _process_strong_tasks->all_tasks_completed();
5188 }
5189
5190 void
5191 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5192 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5193 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5194 }
5195
5196 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5197 private:
5198 BoolObjectClosure* _is_alive;
5199 size_t _initial_string_table_size;
5200
5201 bool _process_strings;
5202 jlong _strings_processed;
5203 jlong _strings_removed;
5204
5205 bool _process_symbols;
5206 jlong _symbols_processed;
5207 jlong _symbols_removed;
5208 public:
5209 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5210 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5211 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5212 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5213
5214 _initial_string_table_size = (size_t)StringTable::the_table()->table_size();
5215 if (process_strings) {
5216 StringTable::clear_parallel_claimed_index();
5217 }
5218 if (process_symbols) {
5219 SymbolTable::clear_parallel_claimed_index();
5220 }
5221 }
5222
5223 ~G1StringSymbolTableUnlinkTask() {
5224 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5225 err_msg("claim value "SIZE_FORMAT" after unlink less than initial string table size "SIZE_FORMAT,
5226 StringTable::parallel_claimed_index(), _initial_string_table_size));
5227 }
5228
5229 void work(uint worker_id) {
5230 size_t strings_processed = 0;
5231 size_t strings_removed = 0;
5232 size_t symbols_processed = 0;
5233 size_t symbols_removed = 0;
5234
5235 if (G1CollectedHeap::use_parallel_gc_threads()) {
5236 if (_process_strings) {
5237 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5238 Atomic::add((jlong)strings_processed, &_strings_processed);
5239 Atomic::add((jlong)strings_removed, &_strings_removed);
5240 }
5241 if (_process_symbols) {
5242 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5243 Atomic::add((jlong)symbols_processed, &_symbols_processed);
5244 Atomic::add((jlong)symbols_removed, &_symbols_removed);
5245 }
5246 } else {
5247 if (_process_strings) {
5248 StringTable::unlink(_is_alive, &strings_processed, &strings_removed);
5249 _strings_processed = strings_processed;
5250 _strings_removed = strings_removed;
5251 }
5252 if (_process_symbols) {
5253 SymbolTable::unlink(&symbols_processed, &symbols_removed);
5254 _symbols_processed = symbols_processed;
5255 _symbols_removed = symbols_removed;
5256 }
5257 }
5258 }
5259
5260 size_t strings_processed() const { return (size_t)_strings_processed; }
5261 size_t strings_removed() const { return (size_t)_strings_removed; }
5262
5263 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5264 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5265 };
5266
5267 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5268 bool process_strings, bool process_symbols) {
5269 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5270 _g1h->workers()->active_workers() : 1);
5271
5272 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5273 if (G1CollectedHeap::use_parallel_gc_threads()) {
5274 set_par_threads(n_workers);
5275 workers()->run_task(&g1_unlink_task);
5276 set_par_threads(0);
5277 } else {
5278 g1_unlink_task.work(0);
5279 }
5280 if (G1TraceStringSymbolTableScrubbing) {
5281 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5282 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5283 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5284 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5285 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5286 }
5287 }
5288
5289 // Weak Reference Processing support
5290
5291 // An always "is_alive" closure that is used to preserve referents.
5292 // If the object is non-null then it's alive. Used in the preservation
5293 // of referent objects that are pointed to by reference objects
5294 // discovered by the CM ref processor.
5295 class G1AlwaysAliveClosure: public BoolObjectClosure {
5296 G1CollectedHeap* _g1;
5297 public:
5298 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5299 bool do_object_b(oop p) {
5300 if (p != NULL) {
5301 return true;
5302 }
5303 return false;
5304 }
5305 };
5306
5307 bool G1STWIsAliveClosure::do_object_b(oop p) {
5308 // An object is reachable if it is outside the collection set,
5309 // or is inside and copied.
5310 return !_g1->obj_in_cs(p) || p->is_forwarded();
5311 }
5312
5313 // Non Copying Keep Alive closure
5314 class G1KeepAliveClosure: public OopClosure {
5315 G1CollectedHeap* _g1;
5316 public:
5317 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5318 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5319 void do_oop( oop* p) {
5320 oop obj = *p;
5321
5322 if (_g1->obj_in_cs(obj)) {
5323 assert( obj->is_forwarded(), "invariant" );
5324 *p = obj->forwardee();
5325 }
5326 }
5327 };
5328
5329 // Copying Keep Alive closure - can be called from both
5330 // serial and parallel code as long as different worker
5331 // threads utilize different G1ParScanThreadState instances
5332 // and different queues.
5333
5334 class G1CopyingKeepAliveClosure: public OopClosure {
5335 G1CollectedHeap* _g1h;
5336 OopClosure* _copy_non_heap_obj_cl;
5337 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5338 G1ParScanThreadState* _par_scan_state;
5339
5340 public:
5341 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5342 OopClosure* non_heap_obj_cl,
5343 OopsInHeapRegionClosure* metadata_obj_cl,
5344 G1ParScanThreadState* pss):
5345 _g1h(g1h),
5346 _copy_non_heap_obj_cl(non_heap_obj_cl),
5347 _copy_metadata_obj_cl(metadata_obj_cl),
5348 _par_scan_state(pss)
5349 {}
5350
5351 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5352 virtual void do_oop( oop* p) { do_oop_work(p); }
5353
5354 template <class T> void do_oop_work(T* p) {
5355 oop obj = oopDesc::load_decode_heap_oop(p);
5356
5357 if (_g1h->obj_in_cs(obj)) {
5358 // If the referent object has been forwarded (either copied
5359 // to a new location or to itself in the event of an
5360 // evacuation failure) then we need to update the reference
5361 // field and, if both reference and referent are in the G1
5362 // heap, update the RSet for the referent.
5363 //
5364 // If the referent has not been forwarded then we have to keep
5365 // it alive by policy. Therefore we have copy the referent.
5366 //
5367 // If the reference field is in the G1 heap then we can push
5368 // on the PSS queue. When the queue is drained (after each
5369 // phase of reference processing) the object and it's followers
5370 // will be copied, the reference field set to point to the
5371 // new location, and the RSet updated. Otherwise we need to
5372 // use the the non-heap or metadata closures directly to copy
5373 // the referent object and update the pointer, while avoiding
5374 // updating the RSet.
5375
5376 if (_g1h->is_in_g1_reserved(p)) {
5377 _par_scan_state->push_on_queue(p);
5378 } else {
5379 assert(!ClassLoaderDataGraph::contains((address)p),
5380 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5381 PTR_FORMAT, p));
5382 _copy_non_heap_obj_cl->do_oop(p);
5383 }
5384 }
5385 }
5386 };
5387
5388 // Serial drain queue closure. Called as the 'complete_gc'
5389 // closure for each discovered list in some of the
5390 // reference processing phases.
5391
5392 class G1STWDrainQueueClosure: public VoidClosure {
5393 protected:
5394 G1CollectedHeap* _g1h;
5395 G1ParScanThreadState* _par_scan_state;
5396
5397 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5398
5399 public:
5400 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5401 _g1h(g1h),
5402 _par_scan_state(pss)
5403 { }
5404
5405 void do_void() {
5406 G1ParScanThreadState* const pss = par_scan_state();
5407 pss->trim_queue();
5408 }
5409 };
5410
5411 // Parallel Reference Processing closures
5412
5413 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5414 // processing during G1 evacuation pauses.
5415
5416 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5417 private:
5418 G1CollectedHeap* _g1h;
5419 RefToScanQueueSet* _queues;
5420 FlexibleWorkGang* _workers;
5421 int _active_workers;
5422
5423 public:
5424 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5425 FlexibleWorkGang* workers,
5426 RefToScanQueueSet *task_queues,
5427 int n_workers) :
5428 _g1h(g1h),
5429 _queues(task_queues),
5430 _workers(workers),
5431 _active_workers(n_workers)
5432 {
5433 assert(n_workers > 0, "shouldn't call this otherwise");
5434 }
5435
5436 // Executes the given task using concurrent marking worker threads.
5437 virtual void execute(ProcessTask& task);
5438 virtual void execute(EnqueueTask& task);
5439 };
5440
5441 // Gang task for possibly parallel reference processing
5442
5443 class G1STWRefProcTaskProxy: public AbstractGangTask {
5444 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5445 ProcessTask& _proc_task;
5446 G1CollectedHeap* _g1h;
5447 RefToScanQueueSet *_task_queues;
5448 ParallelTaskTerminator* _terminator;
5449
5450 public:
5451 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5452 G1CollectedHeap* g1h,
5453 RefToScanQueueSet *task_queues,
5454 ParallelTaskTerminator* terminator) :
5455 AbstractGangTask("Process reference objects in parallel"),
5456 _proc_task(proc_task),
5457 _g1h(g1h),
5458 _task_queues(task_queues),
5459 _terminator(terminator)
5460 {}
5461
5462 virtual void work(uint worker_id) {
5463 // The reference processing task executed by a single worker.
5464 ResourceMark rm;
5465 HandleMark hm;
5466
5467 G1STWIsAliveClosure is_alive(_g1h);
5468
5469 G1ParScanThreadState pss(_g1h, worker_id);
5470
5471 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5472 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5473 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5474
5475 pss.set_evac_closure(&scan_evac_cl);
5476 pss.set_evac_failure_closure(&evac_failure_cl);
5477 pss.set_partial_scan_closure(&partial_scan_cl);
5478
5479 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5480 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5481
5482 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5483 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5484
5485 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5486 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5487
5488 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5489 // We also need to mark copied objects.
5490 copy_non_heap_cl = ©_mark_non_heap_cl;
5491 copy_metadata_cl = ©_mark_metadata_cl;
5492 }
5493
5494 // Keep alive closure.
5495 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5496
5497 // Complete GC closure
5498 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5499
5500 // Call the reference processing task's work routine.
5501 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5502
5503 // Note we cannot assert that the refs array is empty here as not all
5504 // of the processing tasks (specifically phase2 - pp2_work) execute
5505 // the complete_gc closure (which ordinarily would drain the queue) so
5506 // the queue may not be empty.
5507 }
5508 };
5509
5510 // Driver routine for parallel reference processing.
5511 // Creates an instance of the ref processing gang
5512 // task and has the worker threads execute it.
5513 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5514 assert(_workers != NULL, "Need parallel worker threads.");
5515
5516 ParallelTaskTerminator terminator(_active_workers, _queues);
5517 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5518
5519 _g1h->set_par_threads(_active_workers);
5520 _workers->run_task(&proc_task_proxy);
5521 _g1h->set_par_threads(0);
5522 }
5523
5524 // Gang task for parallel reference enqueueing.
5525
5526 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5527 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5528 EnqueueTask& _enq_task;
5529
5530 public:
5531 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5532 AbstractGangTask("Enqueue reference objects in parallel"),
5533 _enq_task(enq_task)
5534 { }
5535
5536 virtual void work(uint worker_id) {
5537 _enq_task.work(worker_id);
5538 }
5539 };
5540
5541 // Driver routine for parallel reference enqueueing.
5542 // Creates an instance of the ref enqueueing gang
5543 // task and has the worker threads execute it.
5544
5545 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5546 assert(_workers != NULL, "Need parallel worker threads.");
5547
5548 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5549
5550 _g1h->set_par_threads(_active_workers);
5551 _workers->run_task(&enq_task_proxy);
5552 _g1h->set_par_threads(0);
5553 }
5554
5555 // End of weak reference support closures
5556
5557 // Abstract task used to preserve (i.e. copy) any referent objects
5558 // that are in the collection set and are pointed to by reference
5559 // objects discovered by the CM ref processor.
5560
5561 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5562 protected:
5563 G1CollectedHeap* _g1h;
5564 RefToScanQueueSet *_queues;
5565 ParallelTaskTerminator _terminator;
5566 uint _n_workers;
5567
5568 public:
5569 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5570 AbstractGangTask("ParPreserveCMReferents"),
5571 _g1h(g1h),
5572 _queues(task_queues),
5573 _terminator(workers, _queues),
5574 _n_workers(workers)
5575 { }
5576
5577 void work(uint worker_id) {
5578 ResourceMark rm;
5579 HandleMark hm;
5580
5581 G1ParScanThreadState pss(_g1h, worker_id);
5582 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5583 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5584 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5585
5586 pss.set_evac_closure(&scan_evac_cl);
5587 pss.set_evac_failure_closure(&evac_failure_cl);
5588 pss.set_partial_scan_closure(&partial_scan_cl);
5589
5590 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5591
5592
5593 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5594 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5595
5596 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5597 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5598
5599 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5600 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5601
5602 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5603 // We also need to mark copied objects.
5604 copy_non_heap_cl = ©_mark_non_heap_cl;
5605 copy_metadata_cl = ©_mark_metadata_cl;
5606 }
5607
5608 // Is alive closure
5609 G1AlwaysAliveClosure always_alive(_g1h);
5610
5611 // Copying keep alive closure. Applied to referent objects that need
5612 // to be copied.
5613 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5614
5615 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5616
5617 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5618 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5619
5620 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5621 // So this must be true - but assert just in case someone decides to
5622 // change the worker ids.
5623 assert(0 <= worker_id && worker_id < limit, "sanity");
5624 assert(!rp->discovery_is_atomic(), "check this code");
5625
5626 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5627 for (uint idx = worker_id; idx < limit; idx += stride) {
5628 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5629
5630 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5631 while (iter.has_next()) {
5632 // Since discovery is not atomic for the CM ref processor, we
5633 // can see some null referent objects.
5634 iter.load_ptrs(DEBUG_ONLY(true));
5635 oop ref = iter.obj();
5636
5637 // This will filter nulls.
5638 if (iter.is_referent_alive()) {
5639 iter.make_referent_alive();
5640 }
5641 iter.move_to_next();
5642 }
5643 }
5644
5645 // Drain the queue - which may cause stealing
5646 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5647 drain_queue.do_void();
5648 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5649 assert(pss.refs()->is_empty(), "should be");
5650 }
5651 };
5652
5653 // Weak Reference processing during an evacuation pause (part 1).
5654 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5655 double ref_proc_start = os::elapsedTime();
5656
5657 ReferenceProcessor* rp = _ref_processor_stw;
5658 assert(rp->discovery_enabled(), "should have been enabled");
5659
5660 // Any reference objects, in the collection set, that were 'discovered'
5661 // by the CM ref processor should have already been copied (either by
5662 // applying the external root copy closure to the discovered lists, or
5663 // by following an RSet entry).
5664 //
5665 // But some of the referents, that are in the collection set, that these
5666 // reference objects point to may not have been copied: the STW ref
5667 // processor would have seen that the reference object had already
5668 // been 'discovered' and would have skipped discovering the reference,
5669 // but would not have treated the reference object as a regular oop.
5670 // As a result the copy closure would not have been applied to the
5671 // referent object.
5672 //
5673 // We need to explicitly copy these referent objects - the references
5674 // will be processed at the end of remarking.
5675 //
5676 // We also need to do this copying before we process the reference
5677 // objects discovered by the STW ref processor in case one of these
5678 // referents points to another object which is also referenced by an
5679 // object discovered by the STW ref processor.
5680
5681 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5682 no_of_gc_workers == workers()->active_workers(),
5683 "Need to reset active GC workers");
5684
5685 set_par_threads(no_of_gc_workers);
5686 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5687 no_of_gc_workers,
5688 _task_queues);
5689
5690 if (G1CollectedHeap::use_parallel_gc_threads()) {
5691 workers()->run_task(&keep_cm_referents);
5692 } else {
5693 keep_cm_referents.work(0);
5694 }
5695
5696 set_par_threads(0);
5697
5698 // Closure to test whether a referent is alive.
5699 G1STWIsAliveClosure is_alive(this);
5700
5701 // Even when parallel reference processing is enabled, the processing
5702 // of JNI refs is serial and performed serially by the current thread
5703 // rather than by a worker. The following PSS will be used for processing
5704 // JNI refs.
5705
5706 // Use only a single queue for this PSS.
5707 G1ParScanThreadState pss(this, 0);
5708
5709 // We do not embed a reference processor in the copying/scanning
5710 // closures while we're actually processing the discovered
5711 // reference objects.
5712 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5713 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5714 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5715
5716 pss.set_evac_closure(&scan_evac_cl);
5717 pss.set_evac_failure_closure(&evac_failure_cl);
5718 pss.set_partial_scan_closure(&partial_scan_cl);
5719
5720 assert(pss.refs()->is_empty(), "pre-condition");
5721
5722 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5723 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5724
5725 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5726 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5727
5728 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5729 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5730
5731 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5732 // We also need to mark copied objects.
5733 copy_non_heap_cl = ©_mark_non_heap_cl;
5734 copy_metadata_cl = ©_mark_metadata_cl;
5735 }
5736
5737 // Keep alive closure.
5738 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5739
5740 // Serial Complete GC closure
5741 G1STWDrainQueueClosure drain_queue(this, &pss);
5742
5743 // Setup the soft refs policy...
5744 rp->setup_policy(false);
5745
5746 ReferenceProcessorStats stats;
5747 if (!rp->processing_is_mt()) {
5748 // Serial reference processing...
5749 stats = rp->process_discovered_references(&is_alive,
5750 &keep_alive,
5751 &drain_queue,
5752 NULL,
5753 _gc_timer_stw);
5754 } else {
5755 // Parallel reference processing
5756 assert(rp->num_q() == no_of_gc_workers, "sanity");
5757 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5758
5759 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5760 stats = rp->process_discovered_references(&is_alive,
5761 &keep_alive,
5762 &drain_queue,
5763 &par_task_executor,
5764 _gc_timer_stw);
5765 }
5766
5767 _gc_tracer_stw->report_gc_reference_stats(stats);
5768 // We have completed copying any necessary live referent objects
5769 // (that were not copied during the actual pause) so we can
5770 // retire any active alloc buffers
5771 pss.retire_alloc_buffers();
5772 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5773
5774 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5775 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5776 }
5777
5778 // Weak Reference processing during an evacuation pause (part 2).
5779 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5780 double ref_enq_start = os::elapsedTime();
5781
5782 ReferenceProcessor* rp = _ref_processor_stw;
5783 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5784
5785 // Now enqueue any remaining on the discovered lists on to
5786 // the pending list.
5787 if (!rp->processing_is_mt()) {
5788 // Serial reference processing...
5789 rp->enqueue_discovered_references();
5790 } else {
5791 // Parallel reference enqueueing
5792
5793 assert(no_of_gc_workers == workers()->active_workers(),
5794 "Need to reset active workers");
5795 assert(rp->num_q() == no_of_gc_workers, "sanity");
5796 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5797
5798 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5799 rp->enqueue_discovered_references(&par_task_executor);
5800 }
5801
5802 rp->verify_no_references_recorded();
5803 assert(!rp->discovery_enabled(), "should have been disabled");
5804
5805 // FIXME
5806 // CM's reference processing also cleans up the string and symbol tables.
5807 // Should we do that here also? We could, but it is a serial operation
5808 // and could significantly increase the pause time.
5809
5810 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5811 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5812 }
5813
5814 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5815 _expand_heap_after_alloc_failure = true;
5816 _evacuation_failed = false;
5817
5818 // Should G1EvacuationFailureALot be in effect for this GC?
5819 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5820
5821 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5822
5823 // Disable the hot card cache.
5824 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5825 hot_card_cache->reset_hot_cache_claimed_index();
5826 hot_card_cache->set_use_cache(false);
5827
5828 uint n_workers;
5829 if (G1CollectedHeap::use_parallel_gc_threads()) {
5830 n_workers =
5831 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5832 workers()->active_workers(),
5833 Threads::number_of_non_daemon_threads());
5834 assert(UseDynamicNumberOfGCThreads ||
5835 n_workers == workers()->total_workers(),
5836 "If not dynamic should be using all the workers");
5837 workers()->set_active_workers(n_workers);
5838 set_par_threads(n_workers);
5839 } else {
5840 assert(n_par_threads() == 0,
5841 "Should be the original non-parallel value");
5842 n_workers = 1;
5843 }
5844
5845 G1ParTask g1_par_task(this, _task_queues);
5846
5847 init_for_evac_failure(NULL);
5848
5849 rem_set()->prepare_for_younger_refs_iterate(true);
5850
5851 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5852 double start_par_time_sec = os::elapsedTime();
5853 double end_par_time_sec;
5854
5855 {
5856 StrongRootsScope srs(this);
5857
5858 if (G1CollectedHeap::use_parallel_gc_threads()) {
5859 // The individual threads will set their evac-failure closures.
5860 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5861 // These tasks use ShareHeap::_process_strong_tasks
5862 assert(UseDynamicNumberOfGCThreads ||
5863 workers()->active_workers() == workers()->total_workers(),
5864 "If not dynamic should be using all the workers");
5865 workers()->run_task(&g1_par_task);
5866 } else {
5867 g1_par_task.set_for_termination(n_workers);
5868 g1_par_task.work(0);
5869 }
5870 end_par_time_sec = os::elapsedTime();
5871
5872 // Closing the inner scope will execute the destructor
5873 // for the StrongRootsScope object. We record the current
5874 // elapsed time before closing the scope so that time
5875 // taken for the SRS destructor is NOT included in the
5876 // reported parallel time.
5877 }
5878
5879 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5880 g1_policy()->phase_times()->record_par_time(par_time_ms);
5881
5882 double code_root_fixup_time_ms =
5883 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5884 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5885
5886 set_par_threads(0);
5887
5888 // Process any discovered reference objects - we have
5889 // to do this _before_ we retire the GC alloc regions
5890 // as we may have to copy some 'reachable' referent
5891 // objects (and their reachable sub-graphs) that were
5892 // not copied during the pause.
5893 process_discovered_references(n_workers);
5894
5895 // Weak root processing.
5896 {
5897 G1STWIsAliveClosure is_alive(this);
5898 G1KeepAliveClosure keep_alive(this);
5899 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5900 }
5901
5902 release_gc_alloc_regions(n_workers, evacuation_info);
5903 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5904
5905 // Reset and re-enable the hot card cache.
5906 // Note the counts for the cards in the regions in the
5907 // collection set are reset when the collection set is freed.
5908 hot_card_cache->reset_hot_cache();
5909 hot_card_cache->set_use_cache(true);
5910
5911 // Migrate the strong code roots attached to each region in
5912 // the collection set. Ideally we would like to do this
5913 // after we have finished the scanning/evacuation of the
5914 // strong code roots for a particular heap region.
5915 migrate_strong_code_roots();
5916
5917 if (g1_policy()->during_initial_mark_pause()) {
5918 // Reset the claim values set during marking the strong code roots
5919 reset_heap_region_claim_values();
5920 }
5921
5922 finalize_for_evac_failure();
5923
5924 if (evacuation_failed()) {
5925 remove_self_forwarding_pointers();
5926
5927 // Reset the G1EvacuationFailureALot counters and flags
5928 // Note: the values are reset only when an actual
5929 // evacuation failure occurs.
5930 NOT_PRODUCT(reset_evacuation_should_fail();)
5931 }
5932
5933 // Enqueue any remaining references remaining on the STW
5934 // reference processor's discovered lists. We need to do
5935 // this after the card table is cleaned (and verified) as
5936 // the act of enqueueing entries on to the pending list
5937 // will log these updates (and dirty their associated
5938 // cards). We need these updates logged to update any
5939 // RSets.
5940 enqueue_discovered_references(n_workers);
5941
5942 if (G1DeferredRSUpdate) {
5943 RedirtyLoggedCardTableEntryFastClosure redirty;
5944 dirty_card_queue_set().set_closure(&redirty);
5945 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5946
5947 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5948 dcq.merge_bufferlists(&dirty_card_queue_set());
5949 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5950 }
5951 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5952 }
5953
5954 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5955 size_t* pre_used,
5956 FreeRegionList* free_list,
5957 OldRegionSet* old_proxy_set,
5958 HumongousRegionSet* humongous_proxy_set,
5959 HRRSCleanupTask* hrrs_cleanup_task,
5960 bool par) {
5961 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5962 if (hr->isHumongous()) {
5963 assert(hr->startsHumongous(), "we should only see starts humongous");
5964 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5965 } else {
5966 _old_set.remove_with_proxy(hr, old_proxy_set);
5967 free_region(hr, pre_used, free_list, par);
5968 }
5969 } else {
5970 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5971 }
5972 }
5973
5974 void G1CollectedHeap::free_region(HeapRegion* hr,
5975 size_t* pre_used,
5976 FreeRegionList* free_list,
5977 bool par) {
5978 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5979 assert(!hr->is_empty(), "the region should not be empty");
5980 assert(free_list != NULL, "pre-condition");
5981
5982 // Clear the card counts for this region.
5983 // Note: we only need to do this if the region is not young
5984 // (since we don't refine cards in young regions).
5985 if (!hr->is_young()) {
5986 _cg1r->hot_card_cache()->reset_card_counts(hr);
5987 }
5988 *pre_used += hr->used();
5989 hr->hr_clear(par, true /* clear_space */);
5990 free_list->add_as_head(hr);
5991 }
5992
5993 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5994 size_t* pre_used,
5995 FreeRegionList* free_list,
5996 HumongousRegionSet* humongous_proxy_set,
5997 bool par) {
5998 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5999 assert(free_list != NULL, "pre-condition");
6000 assert(humongous_proxy_set != NULL, "pre-condition");
6001
6002 size_t hr_used = hr->used();
6003 size_t hr_capacity = hr->capacity();
6004 size_t hr_pre_used = 0;
6005 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
6006 // We need to read this before we make the region non-humongous,
6007 // otherwise the information will be gone.
6008 uint last_index = hr->last_hc_index();
6009 hr->set_notHumongous();
6010 free_region(hr, &hr_pre_used, free_list, par);
6011
6012 uint i = hr->hrs_index() + 1;
6013 while (i < last_index) {
6014 HeapRegion* curr_hr = region_at(i);
6015 assert(curr_hr->continuesHumongous(), "invariant");
6016 curr_hr->set_notHumongous();
6017 free_region(curr_hr, &hr_pre_used, free_list, par);
6018 i += 1;
6019 }
6020 assert(hr_pre_used == hr_used,
6021 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
6022 "should be the same", hr_pre_used, hr_used));
6023 *pre_used += hr_pre_used;
6024 }
6025
6026 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
6027 FreeRegionList* free_list,
6028 OldRegionSet* old_proxy_set,
6029 HumongousRegionSet* humongous_proxy_set,
6030 bool par) {
6031 if (pre_used > 0) {
6032 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
6033 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
6034 assert(_summary_bytes_used >= pre_used,
6035 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
6036 "should be >= pre_used: "SIZE_FORMAT,
6037 _summary_bytes_used, pre_used));
6038 _summary_bytes_used -= pre_used;
6039 }
6040 if (free_list != NULL && !free_list->is_empty()) {
6041 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6042 _free_list.add_as_head(free_list);
6043 }
6044 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
6045 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6046 _old_set.update_from_proxy(old_proxy_set);
6047 }
6048 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
6049 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6050 _humongous_set.update_from_proxy(humongous_proxy_set);
6051 }
6052 }
6053
6054 class G1ParCleanupCTTask : public AbstractGangTask {
6055 G1SATBCardTableModRefBS* _ct_bs;
6056 G1CollectedHeap* _g1h;
6057 HeapRegion* volatile _su_head;
6058 public:
6059 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6060 G1CollectedHeap* g1h) :
6061 AbstractGangTask("G1 Par Cleanup CT Task"),
6062 _ct_bs(ct_bs), _g1h(g1h) { }
6063
6064 void work(uint worker_id) {
6065 HeapRegion* r;
6066 while (r = _g1h->pop_dirty_cards_region()) {
6067 clear_cards(r);
6068 }
6069 }
6070
6071 void clear_cards(HeapRegion* r) {
6072 // Cards of the survivors should have already been dirtied.
6073 if (!r->is_survivor()) {
6074 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6075 }
6076 }
6077 };
6078
6079 #ifndef PRODUCT
6080 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6081 G1CollectedHeap* _g1h;
6082 G1SATBCardTableModRefBS* _ct_bs;
6083 public:
6084 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6085 : _g1h(g1h), _ct_bs(ct_bs) { }
6086 virtual bool doHeapRegion(HeapRegion* r) {
6087 if (r->is_survivor()) {
6088 _g1h->verify_dirty_region(r);
6089 } else {
6090 _g1h->verify_not_dirty_region(r);
6091 }
6092 return false;
6093 }
6094 };
6095
6096 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6097 // All of the region should be clean.
6098 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6099 MemRegion mr(hr->bottom(), hr->end());
6100 ct_bs->verify_not_dirty_region(mr);
6101 }
6102
6103 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6104 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6105 // dirty allocated blocks as they allocate them. The thread that
6106 // retires each region and replaces it with a new one will do a
6107 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6108 // not dirty that area (one less thing to have to do while holding
6109 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6110 // is dirty.
6111 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6112 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6113 if (hr->is_young()) {
6114 ct_bs->verify_g1_young_region(mr);
6115 } else {
6116 ct_bs->verify_dirty_region(mr);
6117 }
6118 }
6119
6120 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6121 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6122 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6123 verify_dirty_region(hr);
6124 }
6125 }
6126
6127 void G1CollectedHeap::verify_dirty_young_regions() {
6128 verify_dirty_young_list(_young_list->first_region());
6129 }
6130 #endif
6131
6132 void G1CollectedHeap::cleanUpCardTable() {
6133 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6134 double start = os::elapsedTime();
6135
6136 {
6137 // Iterate over the dirty cards region list.
6138 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6139
6140 if (G1CollectedHeap::use_parallel_gc_threads()) {
6141 set_par_threads();
6142 workers()->run_task(&cleanup_task);
6143 set_par_threads(0);
6144 } else {
6145 while (_dirty_cards_region_list) {
6146 HeapRegion* r = _dirty_cards_region_list;
6147 cleanup_task.clear_cards(r);
6148 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6149 if (_dirty_cards_region_list == r) {
6150 // The last region.
6151 _dirty_cards_region_list = NULL;
6152 }
6153 r->set_next_dirty_cards_region(NULL);
6154 }
6155 }
6156 #ifndef PRODUCT
6157 if (G1VerifyCTCleanup || VerifyAfterGC) {
6158 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6159 heap_region_iterate(&cleanup_verifier);
6160 }
6161 #endif
6162 }
6163
6164 double elapsed = os::elapsedTime() - start;
6165 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6166 }
6167
6168 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6169 size_t pre_used = 0;
6170 FreeRegionList local_free_list("Local List for CSet Freeing");
6171
6172 double young_time_ms = 0.0;
6173 double non_young_time_ms = 0.0;
6174
6175 // Since the collection set is a superset of the the young list,
6176 // all we need to do to clear the young list is clear its
6177 // head and length, and unlink any young regions in the code below
6178 _young_list->clear();
6179
6180 G1CollectorPolicy* policy = g1_policy();
6181
6182 double start_sec = os::elapsedTime();
6183 bool non_young = true;
6184
6185 HeapRegion* cur = cs_head;
6186 int age_bound = -1;
6187 size_t rs_lengths = 0;
6188
6189 while (cur != NULL) {
6190 assert(!is_on_master_free_list(cur), "sanity");
6191 if (non_young) {
6192 if (cur->is_young()) {
6193 double end_sec = os::elapsedTime();
6194 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6195 non_young_time_ms += elapsed_ms;
6196
6197 start_sec = os::elapsedTime();
6198 non_young = false;
6199 }
6200 } else {
6201 if (!cur->is_young()) {
6202 double end_sec = os::elapsedTime();
6203 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6204 young_time_ms += elapsed_ms;
6205
6206 start_sec = os::elapsedTime();
6207 non_young = true;
6208 }
6209 }
6210
6211 rs_lengths += cur->rem_set()->occupied();
6212
6213 HeapRegion* next = cur->next_in_collection_set();
6214 assert(cur->in_collection_set(), "bad CS");
6215 cur->set_next_in_collection_set(NULL);
6216 cur->set_in_collection_set(false);
6217
6218 if (cur->is_young()) {
6219 int index = cur->young_index_in_cset();
6220 assert(index != -1, "invariant");
6221 assert((uint) index < policy->young_cset_region_length(), "invariant");
6222 size_t words_survived = _surviving_young_words[index];
6223 cur->record_surv_words_in_group(words_survived);
6224
6225 // At this point the we have 'popped' cur from the collection set
6226 // (linked via next_in_collection_set()) but it is still in the
6227 // young list (linked via next_young_region()). Clear the
6228 // _next_young_region field.
6229 cur->set_next_young_region(NULL);
6230 } else {
6231 int index = cur->young_index_in_cset();
6232 assert(index == -1, "invariant");
6233 }
6234
6235 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6236 (!cur->is_young() && cur->young_index_in_cset() == -1),
6237 "invariant" );
6238
6239 if (!cur->evacuation_failed()) {
6240 MemRegion used_mr = cur->used_region();
6241
6242 // And the region is empty.
6243 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6244 free_region(cur, &pre_used, &local_free_list, false /* par */);
6245 } else {
6246 cur->uninstall_surv_rate_group();
6247 if (cur->is_young()) {
6248 cur->set_young_index_in_cset(-1);
6249 }
6250 cur->set_not_young();
6251 cur->set_evacuation_failed(false);
6252 // The region is now considered to be old.
6253 _old_set.add(cur);
6254 evacuation_info.increment_collectionset_used_after(cur->used());
6255 }
6256 cur = next;
6257 }
6258
6259 evacuation_info.set_regions_freed(local_free_list.length());
6260 policy->record_max_rs_lengths(rs_lengths);
6261 policy->cset_regions_freed();
6262
6263 double end_sec = os::elapsedTime();
6264 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6265
6266 if (non_young) {
6267 non_young_time_ms += elapsed_ms;
6268 } else {
6269 young_time_ms += elapsed_ms;
6270 }
6271
6272 update_sets_after_freeing_regions(pre_used, &local_free_list,
6273 NULL /* old_proxy_set */,
6274 NULL /* humongous_proxy_set */,
6275 false /* par */);
6276 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6277 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6278 }
6279
6280 // This routine is similar to the above but does not record
6281 // any policy statistics or update free lists; we are abandoning
6282 // the current incremental collection set in preparation of a
6283 // full collection. After the full GC we will start to build up
6284 // the incremental collection set again.
6285 // This is only called when we're doing a full collection
6286 // and is immediately followed by the tearing down of the young list.
6287
6288 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6289 HeapRegion* cur = cs_head;
6290
6291 while (cur != NULL) {
6292 HeapRegion* next = cur->next_in_collection_set();
6293 assert(cur->in_collection_set(), "bad CS");
6294 cur->set_next_in_collection_set(NULL);
6295 cur->set_in_collection_set(false);
6296 cur->set_young_index_in_cset(-1);
6297 cur = next;
6298 }
6299 }
6300
6301 void G1CollectedHeap::set_free_regions_coming() {
6302 if (G1ConcRegionFreeingVerbose) {
6303 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6304 "setting free regions coming");
6305 }
6306
6307 assert(!free_regions_coming(), "pre-condition");
6308 _free_regions_coming = true;
6309 }
6310
6311 void G1CollectedHeap::reset_free_regions_coming() {
6312 assert(free_regions_coming(), "pre-condition");
6313
6314 {
6315 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6316 _free_regions_coming = false;
6317 SecondaryFreeList_lock->notify_all();
6318 }
6319
6320 if (G1ConcRegionFreeingVerbose) {
6321 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6322 "reset free regions coming");
6323 }
6324 }
6325
6326 void G1CollectedHeap::wait_while_free_regions_coming() {
6327 // Most of the time we won't have to wait, so let's do a quick test
6328 // first before we take the lock.
6329 if (!free_regions_coming()) {
6330 return;
6331 }
6332
6333 if (G1ConcRegionFreeingVerbose) {
6334 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6335 "waiting for free regions");
6336 }
6337
6338 {
6339 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6340 while (free_regions_coming()) {
6341 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6342 }
6343 }
6344
6345 if (G1ConcRegionFreeingVerbose) {
6346 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6347 "done waiting for free regions");
6348 }
6349 }
6350
6351 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6352 assert(heap_lock_held_for_gc(),
6353 "the heap lock should already be held by or for this thread");
6354 _young_list->push_region(hr);
6355 }
6356
6357 class NoYoungRegionsClosure: public HeapRegionClosure {
6358 private:
6359 bool _success;
6360 public:
6361 NoYoungRegionsClosure() : _success(true) { }
6362 bool doHeapRegion(HeapRegion* r) {
6363 if (r->is_young()) {
6364 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6365 r->bottom(), r->end());
6366 _success = false;
6367 }
6368 return false;
6369 }
6370 bool success() { return _success; }
6371 };
6372
6373 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6374 bool ret = _young_list->check_list_empty(check_sample);
6375
6376 if (check_heap) {
6377 NoYoungRegionsClosure closure;
6378 heap_region_iterate(&closure);
6379 ret = ret && closure.success();
6380 }
6381
6382 return ret;
6383 }
6384
6385 class TearDownRegionSetsClosure : public HeapRegionClosure {
6386 private:
6387 OldRegionSet *_old_set;
6388
6389 public:
6390 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6391
6392 bool doHeapRegion(HeapRegion* r) {
6393 if (r->is_empty()) {
6394 // We ignore empty regions, we'll empty the free list afterwards
6395 } else if (r->is_young()) {
6396 // We ignore young regions, we'll empty the young list afterwards
6397 } else if (r->isHumongous()) {
6398 // We ignore humongous regions, we're not tearing down the
6399 // humongous region set
6400 } else {
6401 // The rest should be old
6402 _old_set->remove(r);
6403 }
6404 return false;
6405 }
6406
6407 ~TearDownRegionSetsClosure() {
6408 assert(_old_set->is_empty(), "post-condition");
6409 }
6410 };
6411
6412 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6413 assert_at_safepoint(true /* should_be_vm_thread */);
6414
6415 if (!free_list_only) {
6416 TearDownRegionSetsClosure cl(&_old_set);
6417 heap_region_iterate(&cl);
6418
6419 // Need to do this after the heap iteration to be able to
6420 // recognize the young regions and ignore them during the iteration.
6421 _young_list->empty_list();
6422 }
6423 _free_list.remove_all();
6424 }
6425
6426 class RebuildRegionSetsClosure : public HeapRegionClosure {
6427 private:
6428 bool _free_list_only;
6429 OldRegionSet* _old_set;
6430 FreeRegionList* _free_list;
6431 size_t _total_used;
6432
6433 public:
6434 RebuildRegionSetsClosure(bool free_list_only,
6435 OldRegionSet* old_set, FreeRegionList* free_list) :
6436 _free_list_only(free_list_only),
6437 _old_set(old_set), _free_list(free_list), _total_used(0) {
6438 assert(_free_list->is_empty(), "pre-condition");
6439 if (!free_list_only) {
6440 assert(_old_set->is_empty(), "pre-condition");
6441 }
6442 }
6443
6444 bool doHeapRegion(HeapRegion* r) {
6445 if (r->continuesHumongous()) {
6446 return false;
6447 }
6448
6449 if (r->is_empty()) {
6450 // Add free regions to the free list
6451 _free_list->add_as_tail(r);
6452 } else if (!_free_list_only) {
6453 assert(!r->is_young(), "we should not come across young regions");
6454
6455 if (r->isHumongous()) {
6456 // We ignore humongous regions, we left the humongous set unchanged
6457 } else {
6458 // The rest should be old, add them to the old set
6459 _old_set->add(r);
6460 }
6461 _total_used += r->used();
6462 }
6463
6464 return false;
6465 }
6466
6467 size_t total_used() {
6468 return _total_used;
6469 }
6470 };
6471
6472 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6473 assert_at_safepoint(true /* should_be_vm_thread */);
6474
6475 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6476 heap_region_iterate(&cl);
6477
6478 if (!free_list_only) {
6479 _summary_bytes_used = cl.total_used();
6480 }
6481 assert(_summary_bytes_used == recalculate_used(),
6482 err_msg("inconsistent _summary_bytes_used, "
6483 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6484 _summary_bytes_used, recalculate_used()));
6485 }
6486
6487 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6488 _refine_cte_cl->set_concurrent(concurrent);
6489 }
6490
6491 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6492 HeapRegion* hr = heap_region_containing(p);
6493 if (hr == NULL) {
6494 return false;
6495 } else {
6496 return hr->is_in(p);
6497 }
6498 }
6499
6500 // Methods for the mutator alloc region
6501
6502 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6503 bool force) {
6504 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6505 assert(!force || g1_policy()->can_expand_young_list(),
6506 "if force is true we should be able to expand the young list");
6507 bool young_list_full = g1_policy()->is_young_list_full();
6508 if (force || !young_list_full) {
6509 HeapRegion* new_alloc_region = new_region(word_size,
6510 false /* do_expand */);
6511 if (new_alloc_region != NULL) {
6512 set_region_short_lived_locked(new_alloc_region);
6513 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6514 return new_alloc_region;
6515 }
6516 }
6517 return NULL;
6518 }
6519
6520 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6521 size_t allocated_bytes) {
6522 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6523 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6524
6525 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6526 _summary_bytes_used += allocated_bytes;
6527 _hr_printer.retire(alloc_region);
6528 // We update the eden sizes here, when the region is retired,
6529 // instead of when it's allocated, since this is the point that its
6530 // used space has been recored in _summary_bytes_used.
6531 g1mm()->update_eden_size();
6532 }
6533
6534 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6535 bool force) {
6536 return _g1h->new_mutator_alloc_region(word_size, force);
6537 }
6538
6539 void G1CollectedHeap::set_par_threads() {
6540 // Don't change the number of workers. Use the value previously set
6541 // in the workgroup.
6542 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6543 uint n_workers = workers()->active_workers();
6544 assert(UseDynamicNumberOfGCThreads ||
6545 n_workers == workers()->total_workers(),
6546 "Otherwise should be using the total number of workers");
6547 if (n_workers == 0) {
6548 assert(false, "Should have been set in prior evacuation pause.");
6549 n_workers = ParallelGCThreads;
6550 workers()->set_active_workers(n_workers);
6551 }
6552 set_par_threads(n_workers);
6553 }
6554
6555 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6556 size_t allocated_bytes) {
6557 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6558 }
6559
6560 // Methods for the GC alloc regions
6561
6562 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6563 uint count,
6564 GCAllocPurpose ap) {
6565 assert(FreeList_lock->owned_by_self(), "pre-condition");
6566
6567 if (count < g1_policy()->max_regions(ap)) {
6568 HeapRegion* new_alloc_region = new_region(word_size,
6569 true /* do_expand */);
6570 if (new_alloc_region != NULL) {
6571 // We really only need to do this for old regions given that we
6572 // should never scan survivors. But it doesn't hurt to do it
6573 // for survivors too.
6574 new_alloc_region->set_saved_mark();
6575 if (ap == GCAllocForSurvived) {
6576 new_alloc_region->set_survivor();
6577 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6578 } else {
6579 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6580 }
6581 bool during_im = g1_policy()->during_initial_mark_pause();
6582 new_alloc_region->note_start_of_copying(during_im);
6583 return new_alloc_region;
6584 } else {
6585 g1_policy()->note_alloc_region_limit_reached(ap);
6586 }
6587 }
6588 return NULL;
6589 }
6590
6591 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6592 size_t allocated_bytes,
6593 GCAllocPurpose ap) {
6594 bool during_im = g1_policy()->during_initial_mark_pause();
6595 alloc_region->note_end_of_copying(during_im);
6596 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6597 if (ap == GCAllocForSurvived) {
6598 young_list()->add_survivor_region(alloc_region);
6599 } else {
6600 _old_set.add(alloc_region);
6601 }
6602 _hr_printer.retire(alloc_region);
6603 }
6604
6605 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6606 bool force) {
6607 assert(!force, "not supported for GC alloc regions");
6608 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6609 }
6610
6611 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6612 size_t allocated_bytes) {
6613 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6614 GCAllocForSurvived);
6615 }
6616
6617 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6618 bool force) {
6619 assert(!force, "not supported for GC alloc regions");
6620 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6621 }
6622
6623 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6624 size_t allocated_bytes) {
6625 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6626 GCAllocForTenured);
6627 }
6628 // Heap region set verification
6629
6630 class VerifyRegionListsClosure : public HeapRegionClosure {
6631 private:
6632 FreeRegionList* _free_list;
6633 OldRegionSet* _old_set;
6634 HumongousRegionSet* _humongous_set;
6635 uint _region_count;
6636
6637 public:
6638 VerifyRegionListsClosure(OldRegionSet* old_set,
6639 HumongousRegionSet* humongous_set,
6640 FreeRegionList* free_list) :
6641 _old_set(old_set), _humongous_set(humongous_set),
6642 _free_list(free_list), _region_count(0) { }
6643
6644 uint region_count() { return _region_count; }
6645
6646 bool doHeapRegion(HeapRegion* hr) {
6647 _region_count += 1;
6648
6649 if (hr->continuesHumongous()) {
6650 return false;
6651 }
6652
6653 if (hr->is_young()) {
6654 // TODO
6655 } else if (hr->startsHumongous()) {
6656 _humongous_set->verify_next_region(hr);
6657 } else if (hr->is_empty()) {
6658 _free_list->verify_next_region(hr);
6659 } else {
6660 _old_set->verify_next_region(hr);
6661 }
6662 return false;
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();
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();
6686 }
6687 _old_set.verify();
6688 _humongous_set.verify();
6689
6690 // If a concurrent region freeing operation is in progress it will
6691 // be difficult to correctly attributed any free regions we come
6692 // across to the correct free list given that they might belong to
6693 // one of several (free_list, secondary_free_list, any local lists,
6694 // etc.). So, if that's the case we will skip the rest of the
6695 // verification operation. Alternatively, waiting for the concurrent
6696 // operation to complete will have a non-trivial effect on the GC's
6697 // operation (no concurrent operation will last longer than the
6698 // interval between two calls to verification) and it might hide
6699 // any issues that we would like to catch during testing.
6700 if (free_regions_coming()) {
6701 return;
6702 }
6703
6704 // Make sure we append the secondary_free_list on the free_list so
6705 // that all free regions we will come across can be safely
6706 // attributed to the free_list.
6707 append_secondary_free_list_if_not_empty_with_lock();
6708
6709 // Finally, make sure that the region accounting in the lists is
6710 // consistent with what we see in the heap.
6711 _old_set.verify_start();
6712 _humongous_set.verify_start();
6713 _free_list.verify_start();
6714
6715 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6716 heap_region_iterate(&cl);
6717
6718 _old_set.verify_end();
6719 _humongous_set.verify_end();
6720 _free_list.verify_end();
6721 }
6722
6723 // Optimized nmethod scanning
6724
6725 class RegisterNMethodOopClosure: public OopClosure {
6726 G1CollectedHeap* _g1h;
6727 nmethod* _nm;
6728
6729 template <class T> void do_oop_work(T* p) {
6730 T heap_oop = oopDesc::load_heap_oop(p);
6731 if (!oopDesc::is_null(heap_oop)) {
6732 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6733 HeapRegion* hr = _g1h->heap_region_containing(obj);
6734 assert(!hr->continuesHumongous(),
6735 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6736 " starting at "HR_FORMAT,
6737 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6738
6739 // HeapRegion::add_strong_code_root() avoids adding duplicate
6740 // entries but having duplicates is OK since we "mark" nmethods
6741 // as visited when we scan the strong code root lists during the GC.
6742 hr->add_strong_code_root(_nm);
6743 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6744 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6745 _nm, HR_FORMAT_PARAMS(hr)));
6746 }
6747 }
6748
6749 public:
6750 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6751 _g1h(g1h), _nm(nm) {}
6752
6753 void do_oop(oop* p) { do_oop_work(p); }
6754 void do_oop(narrowOop* p) { do_oop_work(p); }
6755 };
6756
6757 class UnregisterNMethodOopClosure: public OopClosure {
6758 G1CollectedHeap* _g1h;
6759 nmethod* _nm;
6760
6761 template <class T> void do_oop_work(T* p) {
6762 T heap_oop = oopDesc::load_heap_oop(p);
6763 if (!oopDesc::is_null(heap_oop)) {
6764 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6765 HeapRegion* hr = _g1h->heap_region_containing(obj);
6766 assert(!hr->continuesHumongous(),
6767 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6768 " starting at "HR_FORMAT,
6769 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6770
6771 hr->remove_strong_code_root(_nm);
6772 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6773 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6774 _nm, HR_FORMAT_PARAMS(hr)));
6775 }
6776 }
6777
6778 public:
6779 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6780 _g1h(g1h), _nm(nm) {}
6781
6782 void do_oop(oop* p) { do_oop_work(p); }
6783 void do_oop(narrowOop* p) { do_oop_work(p); }
6784 };
6785
6786 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6787 CollectedHeap::register_nmethod(nm);
6788
6789 guarantee(nm != NULL, "sanity");
6790 RegisterNMethodOopClosure reg_cl(this, nm);
6791 nm->oops_do(®_cl);
6792 }
6793
6794 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6795 CollectedHeap::unregister_nmethod(nm);
6796
6797 guarantee(nm != NULL, "sanity");
6798 UnregisterNMethodOopClosure reg_cl(this, nm);
6799 nm->oops_do(®_cl, true);
6800 }
6801
6802 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6803 public:
6804 bool doHeapRegion(HeapRegion *hr) {
6805 assert(!hr->isHumongous(),
6806 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6807 HR_FORMAT_PARAMS(hr)));
6808 hr->migrate_strong_code_roots();
6809 return false;
6810 }
6811 };
6812
6813 void G1CollectedHeap::migrate_strong_code_roots() {
6814 MigrateCodeRootsHeapRegionClosure cl;
6815 double migrate_start = os::elapsedTime();
6816 collection_set_iterate(&cl);
6817 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6818 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6819 }
6820
6821 // Mark all the code roots that point into regions *not* in the
6822 // collection set.
6823 //
6824 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6825 // walking the the code roots lists of regions not in the collection
6826 // set. Suppose we have an nmethod (M) that points to objects in two
6827 // separate regions - one in the collection set (R1) and one not (R2).
6828 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6829 // nmethod M when walking the code roots for R1. When we come to scan
6830 // the code roots for R2, we would see that M is already marked and it
6831 // would be skipped and the objects in R2 that are referenced from M
6832 // would not be evacuated.
6833
6834 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6835
6836 class MarkStrongCodeRootOopClosure: public OopClosure {
6837 ConcurrentMark* _cm;
6838 HeapRegion* _hr;
6839 uint _worker_id;
6840
6841 template <class T> void do_oop_work(T* p) {
6842 T heap_oop = oopDesc::load_heap_oop(p);
6843 if (!oopDesc::is_null(heap_oop)) {
6844 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6845 // Only mark objects in the region (which is assumed
6846 // to be not in the collection set).
6847 if (_hr->is_in(obj)) {
6848 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6849 }
6850 }
6851 }
6852
6853 public:
6854 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6855 _cm(cm), _hr(hr), _worker_id(worker_id) {
6856 assert(!_hr->in_collection_set(), "sanity");
6857 }
6858
6859 void do_oop(narrowOop* p) { do_oop_work(p); }
6860 void do_oop(oop* p) { do_oop_work(p); }
6861 };
6862
6863 MarkStrongCodeRootOopClosure _oop_cl;
6864
6865 public:
6866 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6867 _oop_cl(cm, hr, worker_id) {}
6868
6869 void do_code_blob(CodeBlob* cb) {
6870 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6871 if (nm != NULL) {
6872 nm->oops_do(&_oop_cl);
6873 }
6874 }
6875 };
6876
6877 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6878 G1CollectedHeap* _g1h;
6879 uint _worker_id;
6880
6881 public:
6882 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6883 _g1h(g1h), _worker_id(worker_id) {}
6884
6885 bool doHeapRegion(HeapRegion *hr) {
6886 HeapRegionRemSet* hrrs = hr->rem_set();
6887 if (hr->continuesHumongous()) {
6888 // Code roots should never be attached to a continuation of a humongous region
6889 assert(hrrs->strong_code_roots_list_length() == 0,
6890 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6891 " starting at "HR_FORMAT", but has "INT32_FORMAT,
6892 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6893 hrrs->strong_code_roots_list_length()));
6894 return false;
6895 }
6896
6897 if (hr->in_collection_set()) {
6898 // Don't mark code roots into regions in the collection set here.
6899 // They will be marked when we scan them.
6900 return false;
6901 }
6902
6903 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6904 hr->strong_code_roots_do(&cb_cl);
6905 return false;
6906 }
6907 };
6908
6909 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6910 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6911 if (G1CollectedHeap::use_parallel_gc_threads()) {
6912 heap_region_par_iterate_chunked(&cl,
6913 worker_id,
6914 workers()->active_workers(),
6915 HeapRegion::ParMarkRootClaimValue);
6916 } else {
6917 heap_region_iterate(&cl);
6918 }
6919 }
6920
6921 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6922 G1CollectedHeap* _g1h;
6923
6924 public:
6925 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6926 _g1h(g1h) {}
6927
6928 void do_code_blob(CodeBlob* cb) {
6929 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6930 if (nm == NULL) {
6931 return;
6932 }
6933
6934 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6935 _g1h->register_nmethod(nm);
6936 }
6937 }
6938 };
6939
6940 void G1CollectedHeap::rebuild_strong_code_roots() {
6941 RebuildStrongCodeRootClosure blob_cl(this);
6942 CodeCache::blobs_do(&blob_cl);
6943 }