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/generationSpec.hpp"
54 #include "memory/iterator.hpp"
55 #include "memory/referenceProcessor.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/oop.pcgc.inline.hpp"
58 #include "runtime/vmThread.hpp"
59 #include "utilities/ticks.hpp"
60
61 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
62
63 // turn it on so that the contents of the young list (scan-only /
64 // to-be-collected) are printed at "strategic" points before / during
65 // / after the collection --- this is useful for debugging
66 #define YOUNG_LIST_VERBOSE 0
67 // CURRENT STATUS
68 // This file is under construction. Search for "FIXME".
69
70 // INVARIANTS/NOTES
71 //
72 // All allocation activity covered by the G1CollectedHeap interface is
73 // serialized by acquiring the HeapLock. This happens in mem_allocate
74 // and allocate_new_tlab, which are the "entry" points to the
75 // allocation code from the rest of the JVM. (Note that this does not
76 // apply to TLAB allocation, which is not part of this interface: it
77 // is done by clients of this interface.)
78
79 // Notes on implementation of parallelism in different tasks.
80 //
81 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
82 // The number of GC workers is passed to heap_region_par_iterate_chunked().
83 // It does use run_task() which sets _n_workers in the task.
84 // G1ParTask executes g1_process_strong_roots() ->
85 // SharedHeap::process_strong_roots() which calls eventually to
86 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
87 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
88 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
89 //
90
91 // Local to this file.
92
93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
94 SuspendibleThreadSet* _sts;
95 G1RemSet* _g1rs;
96 ConcurrentG1Refine* _cg1r;
97 bool _concurrent;
98 public:
99 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
100 G1RemSet* g1rs,
101 ConcurrentG1Refine* cg1r) :
102 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
103 {}
104 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
105 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
106 // This path is executed by the concurrent refine or mutator threads,
107 // concurrently, and so we do not care if card_ptr contains references
108 // that point into the collection set.
109 assert(!oops_into_cset, "should be");
110
111 if (_concurrent && _sts->should_yield()) {
112 // Caller will actually yield.
113 return false;
114 }
115 // Otherwise, we finished successfully; return true.
116 return true;
117 }
118 void set_concurrent(bool b) { _concurrent = b; }
119 };
120
121
122 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
123 int _calls;
124 G1CollectedHeap* _g1h;
125 CardTableModRefBS* _ctbs;
126 int _histo[256];
127 public:
128 ClearLoggedCardTableEntryClosure() :
129 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
130 {
131 for (int i = 0; i < 256; i++) _histo[i] = 0;
132 }
133 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
134 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
135 _calls++;
136 unsigned char* ujb = (unsigned char*)card_ptr;
137 int ind = (int)(*ujb);
138 _histo[ind]++;
139 *card_ptr = -1;
140 }
141 return true;
142 }
143 int calls() { return _calls; }
144 void print_histo() {
145 gclog_or_tty->print_cr("Card table value histogram:");
146 for (int i = 0; i < 256; i++) {
147 if (_histo[i] != 0) {
148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
149 }
150 }
151 }
152 };
153
154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
155 int _calls;
156 G1CollectedHeap* _g1h;
157 CardTableModRefBS* _ctbs;
158 public:
159 RedirtyLoggedCardTableEntryClosure() :
160 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
161
162 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
163 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
164 _calls++;
165 *card_ptr = 0;
166 }
167 return true;
168 }
169 int calls() { return _calls; }
170 };
171
172 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
173 public:
174 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
175 *card_ptr = CardTableModRefBS::dirty_card_val();
176 return true;
177 }
178 };
179
180 YoungList::YoungList(G1CollectedHeap* g1h) :
181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
183 guarantee(check_list_empty(false), "just making sure...");
184 }
185
186 void YoungList::push_region(HeapRegion *hr) {
187 assert(!hr->is_young(), "should not already be young");
188 assert(hr->get_next_young_region() == NULL, "cause it should!");
189
190 hr->set_next_young_region(_head);
191 _head = hr;
192
193 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
194 ++_length;
195 }
196
197 void YoungList::add_survivor_region(HeapRegion* hr) {
198 assert(hr->is_survivor(), "should be flagged as survivor region");
199 assert(hr->get_next_young_region() == NULL, "cause it should!");
200
201 hr->set_next_young_region(_survivor_head);
202 if (_survivor_head == NULL) {
203 _survivor_tail = hr;
204 }
205 _survivor_head = hr;
206 ++_survivor_length;
207 }
208
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 list->set_not_young();
215 list = next;
216 }
217 }
218
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
221
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
225
226 empty_list(_survivor_head);
227 _survivor_head = NULL;
228 _survivor_tail = NULL;
229 _survivor_length = 0;
230
231 _last_sampled_rs_lengths = 0;
232
233 assert(check_list_empty(false), "just making sure...");
234 }
235
236 bool YoungList::check_list_well_formed() {
237 bool ret = true;
238
239 uint length = 0;
240 HeapRegion* curr = _head;
241 HeapRegion* last = NULL;
242 while (curr != NULL) {
243 if (!curr->is_young()) {
244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
245 "incorrectly tagged (y: %d, surv: %d)",
246 curr->bottom(), curr->end(),
247 curr->is_young(), curr->is_survivor());
248 ret = false;
249 }
250 ++length;
251 last = curr;
252 curr = curr->get_next_young_region();
253 }
254 ret = ret && (length == _length);
255
256 if (!ret) {
257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
258 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
259 length, _length);
260 }
261
262 return ret;
263 }
264
265 bool YoungList::check_list_empty(bool check_sample) {
266 bool ret = true;
267
268 if (_length != 0) {
269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
270 _length);
271 ret = false;
272 }
273 if (check_sample && _last_sampled_rs_lengths != 0) {
274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
275 ret = false;
276 }
277 if (_head != NULL) {
278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
279 ret = false;
280 }
281 if (!ret) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
283 }
284
285 return ret;
286 }
287
288 void
289 YoungList::rs_length_sampling_init() {
290 _sampled_rs_lengths = 0;
291 _curr = _head;
292 }
293
294 bool
295 YoungList::rs_length_sampling_more() {
296 return _curr != NULL;
297 }
298
299 void
300 YoungList::rs_length_sampling_next() {
301 assert( _curr != NULL, "invariant" );
302 size_t rs_length = _curr->rem_set()->occupied();
303
304 _sampled_rs_lengths += rs_length;
305
306 // The current region may not yet have been added to the
307 // incremental collection set (it gets added when it is
308 // retired as the current allocation region).
309 if (_curr->in_collection_set()) {
310 // Update the collection set policy information for this region
311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
312 }
313
314 _curr = _curr->get_next_young_region();
315 if (_curr == NULL) {
316 _last_sampled_rs_lengths = _sampled_rs_lengths;
317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
318 }
319 }
320
321 void
322 YoungList::reset_auxilary_lists() {
323 guarantee( is_empty(), "young list should be empty" );
324 assert(check_list_well_formed(), "young list should be well formed");
325
326 // Add survivor regions to SurvRateGroup.
327 _g1h->g1_policy()->note_start_adding_survivor_regions();
328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
329
330 int young_index_in_cset = 0;
331 for (HeapRegion* curr = _survivor_head;
332 curr != NULL;
333 curr = curr->get_next_young_region()) {
334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
335
336 // The region is a non-empty survivor so let's add it to
337 // the incremental collection set for the next evacuation
338 // pause.
339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
340 young_index_in_cset += 1;
341 }
342 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
343 _g1h->g1_policy()->note_stop_adding_survivor_regions();
344
345 _head = _survivor_head;
346 _length = _survivor_length;
347 if (_survivor_head != NULL) {
348 assert(_survivor_tail != NULL, "cause it shouldn't be");
349 assert(_survivor_length > 0, "invariant");
350 _survivor_tail->set_next_young_region(NULL);
351 }
352
353 // Don't clear the survivor list handles until the start of
354 // the next evacuation pause - we need it in order to re-tag
355 // the survivor regions from this evacuation pause as 'young'
356 // at the start of the next.
357
358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
359
360 assert(check_list_well_formed(), "young list should be well formed");
361 }
362
363 void YoungList::print() {
364 HeapRegion* lists[] = {_head, _survivor_head};
365 const char* names[] = {"YOUNG", "SURVIVOR"};
366
367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
369 HeapRegion *curr = lists[list];
370 if (curr == NULL)
371 gclog_or_tty->print_cr(" empty");
372 while (curr != NULL) {
373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
374 HR_FORMAT_PARAMS(curr),
375 curr->prev_top_at_mark_start(),
376 curr->next_top_at_mark_start(),
377 curr->age_in_surv_rate_group_cond());
378 curr = curr->get_next_young_region();
379 }
380 }
381
382 gclog_or_tty->print_cr("");
383 }
384
385 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
386 {
387 // Claim the right to put the region on the dirty cards region list
388 // by installing a self pointer.
389 HeapRegion* next = hr->get_next_dirty_cards_region();
390 if (next == NULL) {
391 HeapRegion* res = (HeapRegion*)
392 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
393 NULL);
394 if (res == NULL) {
395 HeapRegion* head;
396 do {
397 // Put the region to the dirty cards region list.
398 head = _dirty_cards_region_list;
399 next = (HeapRegion*)
400 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
401 if (next == head) {
402 assert(hr->get_next_dirty_cards_region() == hr,
403 "hr->get_next_dirty_cards_region() != hr");
404 if (next == NULL) {
405 // The last region in the list points to itself.
406 hr->set_next_dirty_cards_region(hr);
407 } else {
408 hr->set_next_dirty_cards_region(next);
409 }
410 }
411 } while (next != head);
412 }
413 }
414 }
415
416 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
417 {
418 HeapRegion* head;
419 HeapRegion* hr;
420 do {
421 head = _dirty_cards_region_list;
422 if (head == NULL) {
423 return NULL;
424 }
425 HeapRegion* new_head = head->get_next_dirty_cards_region();
426 if (head == new_head) {
427 // The last region.
428 new_head = NULL;
429 }
430 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
431 head);
432 } while (hr != head);
433 assert(hr != NULL, "invariant");
434 hr->set_next_dirty_cards_region(NULL);
435 return hr;
436 }
437
438 void G1CollectedHeap::stop_conc_gc_threads() {
439 _cg1r->stop();
440 _cmThread->stop();
441 }
442
443 #ifdef ASSERT
444 // A region is added to the collection set as it is retired
445 // so an address p can point to a region which will be in the
446 // collection set but has not yet been retired. This method
447 // therefore is only accurate during a GC pause after all
448 // regions have been retired. It is used for debugging
449 // to check if an nmethod has references to objects that can
450 // be move during a partial collection. Though it can be
451 // inaccurate, it is sufficient for G1 because the conservative
452 // implementation of is_scavengable() for G1 will indicate that
453 // all nmethods must be scanned during a partial collection.
454 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
455 HeapRegion* hr = heap_region_containing(p);
456 return hr != NULL && hr->in_collection_set();
457 }
458 #endif
459
460 // Returns true if the reference points to an object that
461 // can move in an incremental collection.
462 bool G1CollectedHeap::is_scavengable(const void* p) {
463 G1CollectedHeap* g1h = G1CollectedHeap::heap();
464 G1CollectorPolicy* g1p = g1h->g1_policy();
465 HeapRegion* hr = heap_region_containing(p);
466 if (hr == NULL) {
467 // null
468 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
469 return false;
470 } else {
471 return !hr->isHumongous();
472 }
473 }
474
475 void G1CollectedHeap::check_ct_logs_at_safepoint() {
476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
477 CardTableModRefBS* ct_bs = g1_barrier_set();
478
479 // Count the dirty cards at the start.
480 CountNonCleanMemRegionClosure count1(this);
481 ct_bs->mod_card_iterate(&count1);
482 int orig_count = count1.n();
483
484 // First clear the logged cards.
485 ClearLoggedCardTableEntryClosure clear;
486 dcqs.set_closure(&clear);
487 dcqs.apply_closure_to_all_completed_buffers();
488 dcqs.iterate_closure_all_threads(false);
489 clear.print_histo();
490
491 // Now ensure that there's no dirty cards.
492 CountNonCleanMemRegionClosure count2(this);
493 ct_bs->mod_card_iterate(&count2);
494 if (count2.n() != 0) {
495 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
496 count2.n(), orig_count);
497 }
498 guarantee(count2.n() == 0, "Card table should be clean.");
499
500 RedirtyLoggedCardTableEntryClosure redirty;
501 JavaThread::dirty_card_queue_set().set_closure(&redirty);
502 dcqs.apply_closure_to_all_completed_buffers();
503 dcqs.iterate_closure_all_threads(false);
504 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
505 clear.calls(), orig_count);
506 guarantee(redirty.calls() == clear.calls(),
507 "Or else mechanism is broken.");
508
509 CountNonCleanMemRegionClosure count3(this);
510 ct_bs->mod_card_iterate(&count3);
511 if (count3.n() != orig_count) {
512 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
513 orig_count, count3.n());
514 guarantee(count3.n() >= orig_count, "Should have restored them all.");
515 }
516
517 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
518 }
519
520 // Private class members.
521
522 G1CollectedHeap* G1CollectedHeap::_g1h;
523
524 // Private methods.
525
526 HeapRegion*
527 G1CollectedHeap::new_region_try_secondary_free_list() {
528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
529 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
530 if (!_secondary_free_list.is_empty()) {
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "secondary_free_list has %u entries",
534 _secondary_free_list.length());
535 }
536 // It looks as if there are free regions available on the
537 // secondary_free_list. Let's move them to the free_list and try
538 // again to allocate from it.
539 append_secondary_free_list();
540
541 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
542 "empty we should have moved at least one entry to the free_list");
543 HeapRegion* res = _free_list.remove_head();
544 if (G1ConcRegionFreeingVerbose) {
545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
546 "allocated "HR_FORMAT" from secondary_free_list",
547 HR_FORMAT_PARAMS(res));
548 }
549 return res;
550 }
551
552 // Wait here until we get notified either when (a) there are no
553 // more free regions coming or (b) some regions have been moved on
554 // the secondary_free_list.
555 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
556 }
557
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "could not allocate from secondary_free_list");
561 }
562 return NULL;
563 }
564
565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
566 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
567 "the only time we use this to allocate a humongous region is "
568 "when we are allocating a single humongous region");
569
570 HeapRegion* res;
571 if (G1StressConcRegionFreeing) {
572 if (!_secondary_free_list.is_empty()) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "forced to look at the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list();
578 if (res != NULL) {
579 return res;
580 }
581 }
582 }
583 res = _free_list.remove_head_or_null();
584 if (res == NULL) {
585 if (G1ConcRegionFreeingVerbose) {
586 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
587 "res == NULL, trying the secondary_free_list");
588 }
589 res = new_region_try_secondary_free_list();
590 }
591 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
592 // Currently, only attempts to allocate GC alloc regions set
593 // do_expand to true. So, we should only reach here during a
594 // safepoint. If this assumption changes we might have to
595 // reconsider the use of _expand_heap_after_alloc_failure.
596 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
597
598 ergo_verbose1(ErgoHeapSizing,
599 "attempt heap expansion",
600 ergo_format_reason("region allocation request failed")
601 ergo_format_byte("allocation request"),
602 word_size * HeapWordSize);
603 if (expand(word_size * HeapWordSize)) {
604 // Given that expand() succeeded in expanding the heap, and we
605 // always expand the heap by an amount aligned to the heap
606 // region size, the free list should in theory not be empty. So
607 // it would probably be OK to use remove_head(). But the extra
608 // check for NULL is unlikely to be a performance issue here (we
609 // just expanded the heap!) so let's just be conservative and
610 // use remove_head_or_null().
611 res = _free_list.remove_head_or_null();
612 } else {
613 _expand_heap_after_alloc_failure = false;
614 }
615 }
616 return res;
617 }
618
619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
620 size_t word_size) {
621 assert(isHumongous(word_size), "word_size should be humongous");
622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
623
624 uint first = G1_NULL_HRS_INDEX;
625 if (num_regions == 1) {
626 // Only one region to allocate, no need to go through the slower
627 // path. The caller will attempt the expansion if this fails, so
628 // let's not try to expand here too.
629 HeapRegion* hr = new_region(word_size, false /* do_expand */);
630 if (hr != NULL) {
631 first = hr->hrs_index();
632 } else {
633 first = G1_NULL_HRS_INDEX;
634 }
635 } else {
636 // We can't allocate humongous regions while cleanupComplete() is
637 // running, since some of the regions we find to be empty might not
638 // yet be added to the free list and it is not straightforward to
639 // know which list they are on so that we can remove them. Note
640 // that we only need to do this if we need to allocate more than
641 // one region to satisfy the current humongous allocation
642 // request. If we are only allocating one region we use the common
643 // region allocation code (see above).
644 wait_while_free_regions_coming();
645 append_secondary_free_list_if_not_empty_with_lock();
646
647 if (free_regions() >= num_regions) {
648 first = _hrs.find_contiguous(num_regions);
649 if (first != G1_NULL_HRS_INDEX) {
650 for (uint i = first; i < first + num_regions; ++i) {
651 HeapRegion* hr = region_at(i);
652 assert(hr->is_empty(), "sanity");
653 assert(is_on_master_free_list(hr), "sanity");
654 hr->set_pending_removal(true);
655 }
656 _free_list.remove_all_pending(num_regions);
657 }
658 }
659 }
660 return first;
661 }
662
663 HeapWord*
664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
665 uint num_regions,
666 size_t word_size) {
667 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
668 assert(isHumongous(word_size), "word_size should be humongous");
669 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
670
671 // Index of last region in the series + 1.
672 uint last = first + num_regions;
673
674 // We need to initialize the region(s) we just discovered. This is
675 // a bit tricky given that it can happen concurrently with
676 // refinement threads refining cards on these regions and
677 // potentially wanting to refine the BOT as they are scanning
678 // those cards (this can happen shortly after a cleanup; see CR
679 // 6991377). So we have to set up the region(s) carefully and in
680 // a specific order.
681
682 // The word size sum of all the regions we will allocate.
683 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
684 assert(word_size <= word_size_sum, "sanity");
685
686 // This will be the "starts humongous" region.
687 HeapRegion* first_hr = region_at(first);
688 // The header of the new object will be placed at the bottom of
689 // the first region.
690 HeapWord* new_obj = first_hr->bottom();
691 // This will be the new end of the first region in the series that
692 // should also match the end of the last region in the series.
693 HeapWord* new_end = new_obj + word_size_sum;
694 // This will be the new top of the first region that will reflect
695 // this allocation.
696 HeapWord* new_top = new_obj + word_size;
697
698 // First, we need to zero the header of the space that we will be
699 // allocating. When we update top further down, some refinement
700 // threads might try to scan the region. By zeroing the header we
701 // ensure that any thread that will try to scan the region will
702 // come across the zero klass word and bail out.
703 //
704 // NOTE: It would not have been correct to have used
705 // CollectedHeap::fill_with_object() and make the space look like
706 // an int array. The thread that is doing the allocation will
707 // later update the object header to a potentially different array
708 // type and, for a very short period of time, the klass and length
709 // fields will be inconsistent. This could cause a refinement
710 // thread to calculate the object size incorrectly.
711 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
712
713 // We will set up the first region as "starts humongous". This
714 // will also update the BOT covering all the regions to reflect
715 // that there is a single object that starts at the bottom of the
716 // first region.
717 first_hr->set_startsHumongous(new_top, new_end);
718
719 // Then, if there are any, we will set up the "continues
720 // humongous" regions.
721 HeapRegion* hr = NULL;
722 for (uint i = first + 1; i < last; ++i) {
723 hr = region_at(i);
724 hr->set_continuesHumongous(first_hr);
725 }
726 // If we have "continues humongous" regions (hr != NULL), then the
727 // end of the last one should match new_end.
728 assert(hr == NULL || hr->end() == new_end, "sanity");
729
730 // Up to this point no concurrent thread would have been able to
731 // do any scanning on any region in this series. All the top
732 // fields still point to bottom, so the intersection between
733 // [bottom,top] and [card_start,card_end] will be empty. Before we
734 // update the top fields, we'll do a storestore to make sure that
735 // no thread sees the update to top before the zeroing of the
736 // object header and the BOT initialization.
737 OrderAccess::storestore();
738
739 // Now that the BOT and the object header have been initialized,
740 // we can update top of the "starts humongous" region.
741 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
742 "new_top should be in this region");
743 first_hr->set_top(new_top);
744 if (_hr_printer.is_active()) {
745 HeapWord* bottom = first_hr->bottom();
746 HeapWord* end = first_hr->orig_end();
747 if ((first + 1) == last) {
748 // the series has a single humongous region
749 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
750 } else {
751 // the series has more than one humongous regions
752 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
753 }
754 }
755
756 // Now, we will update the top fields of the "continues humongous"
757 // regions. The reason we need to do this is that, otherwise,
758 // these regions would look empty and this will confuse parts of
759 // G1. For example, the code that looks for a consecutive number
760 // of empty regions will consider them empty and try to
761 // re-allocate them. We can extend is_empty() to also include
762 // !continuesHumongous(), but it is easier to just update the top
763 // fields here. The way we set top for all regions (i.e., top ==
764 // end for all regions but the last one, top == new_top for the
765 // last one) is actually used when we will free up the humongous
766 // region in free_humongous_region().
767 hr = NULL;
768 for (uint i = first + 1; i < last; ++i) {
769 hr = region_at(i);
770 if ((i + 1) == last) {
771 // last continues humongous region
772 assert(hr->bottom() < new_top && new_top <= hr->end(),
773 "new_top should fall on this region");
774 hr->set_top(new_top);
775 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
776 } else {
777 // not last one
778 assert(new_top > hr->end(), "new_top should be above this region");
779 hr->set_top(hr->end());
780 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
781 }
782 }
783 // If we have continues humongous regions (hr != NULL), then the
784 // end of the last one should match new_end and its top should
785 // match new_top.
786 assert(hr == NULL ||
787 (hr->end() == new_end && hr->top() == new_top), "sanity");
788
789 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
790 _summary_bytes_used += first_hr->used();
791 _humongous_set.add(first_hr);
792
793 return new_obj;
794 }
795
796 // If could fit into free regions w/o expansion, try.
797 // Otherwise, if can expand, do so.
798 // Otherwise, if using ex regions might help, try with ex given back.
799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
800 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
801
802 verify_region_sets_optional();
803
804 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
805 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
806 uint x_num = expansion_regions();
807 uint fs = _hrs.free_suffix();
808 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
809 if (first == G1_NULL_HRS_INDEX) {
810 // The only thing we can do now is attempt expansion.
811 if (fs + x_num >= num_regions) {
812 // If the number of regions we're trying to allocate for this
813 // object is at most the number of regions in the free suffix,
814 // then the call to humongous_obj_allocate_find_first() above
815 // should have succeeded and we wouldn't be here.
816 //
817 // We should only be trying to expand when the free suffix is
818 // not sufficient for the object _and_ we have some expansion
819 // room available.
820 assert(num_regions > fs, "earlier allocation should have succeeded");
821
822 ergo_verbose1(ErgoHeapSizing,
823 "attempt heap expansion",
824 ergo_format_reason("humongous allocation request failed")
825 ergo_format_byte("allocation request"),
826 word_size * HeapWordSize);
827 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
828 // Even though the heap was expanded, it might not have
829 // reached the desired size. So, we cannot assume that the
830 // allocation will succeed.
831 first = humongous_obj_allocate_find_first(num_regions, word_size);
832 }
833 }
834 }
835
836 HeapWord* result = NULL;
837 if (first != G1_NULL_HRS_INDEX) {
838 result =
839 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
840 assert(result != NULL, "it should always return a valid result");
841
842 // A successful humongous object allocation changes the used space
843 // information of the old generation so we need to recalculate the
844 // sizes and update the jstat counters here.
845 g1mm()->update_sizes();
846 }
847
848 verify_region_sets_optional();
849
850 return result;
851 }
852
853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
856
857 unsigned int dummy_gc_count_before;
858 int dummy_gclocker_retry_count = 0;
859 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
860 }
861
862 HeapWord*
863 G1CollectedHeap::mem_allocate(size_t word_size,
864 bool* gc_overhead_limit_was_exceeded) {
865 assert_heap_not_locked_and_not_at_safepoint();
866
867 // Loop until the allocation is satisfied, or unsatisfied after GC.
868 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
869 unsigned int gc_count_before;
870
871 HeapWord* result = NULL;
872 if (!isHumongous(word_size)) {
873 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
874 } else {
875 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
876 }
877 if (result != NULL) {
878 return result;
879 }
880
881 // Create the garbage collection operation...
882 VM_G1CollectForAllocation op(gc_count_before, word_size);
883 // ...and get the VM thread to execute it.
884 VMThread::execute(&op);
885
886 if (op.prologue_succeeded() && op.pause_succeeded()) {
887 // If the operation was successful we'll return the result even
888 // if it is NULL. If the allocation attempt failed immediately
889 // after a Full GC, it's unlikely we'll be able to allocate now.
890 HeapWord* result = op.result();
891 if (result != NULL && !isHumongous(word_size)) {
892 // Allocations that take place on VM operations do not do any
893 // card dirtying and we have to do it here. We only have to do
894 // this for non-humongous allocations, though.
895 dirty_young_block(result, word_size);
896 }
897 return result;
898 } else {
899 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
900 return NULL;
901 }
902 assert(op.result() == NULL,
903 "the result should be NULL if the VM op did not succeed");
904 }
905
906 // Give a warning if we seem to be looping forever.
907 if ((QueuedAllocationWarningCount > 0) &&
908 (try_count % QueuedAllocationWarningCount == 0)) {
909 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
910 }
911 }
912
913 ShouldNotReachHere();
914 return NULL;
915 }
916
917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
918 unsigned int *gc_count_before_ret,
919 int* gclocker_retry_count_ret) {
920 // Make sure you read the note in attempt_allocation_humongous().
921
922 assert_heap_not_locked_and_not_at_safepoint();
923 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
924 "be called for humongous allocation requests");
925
926 // We should only get here after the first-level allocation attempt
927 // (attempt_allocation()) failed to allocate.
928
929 // We will loop until a) we manage to successfully perform the
930 // allocation or b) we successfully schedule a collection which
931 // fails to perform the allocation. b) is the only case when we'll
932 // return NULL.
933 HeapWord* result = NULL;
934 for (int try_count = 1; /* we'll return */; try_count += 1) {
935 bool should_try_gc;
936 unsigned int gc_count_before;
937
938 {
939 MutexLockerEx x(Heap_lock);
940
941 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
942 false /* bot_updates */);
943 if (result != NULL) {
944 return result;
945 }
946
947 // If we reach here, attempt_allocation_locked() above failed to
948 // allocate a new region. So the mutator alloc region should be NULL.
949 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
950
951 if (GC_locker::is_active_and_needs_gc()) {
952 if (g1_policy()->can_expand_young_list()) {
953 // No need for an ergo verbose message here,
954 // can_expand_young_list() does this when it returns true.
955 result = _mutator_alloc_region.attempt_allocation_force(word_size,
956 false /* bot_updates */);
957 if (result != NULL) {
958 return result;
959 }
960 }
961 should_try_gc = false;
962 } else {
963 // The GCLocker may not be active but the GCLocker initiated
964 // GC may not yet have been performed (GCLocker::needs_gc()
965 // returns true). In this case we do not try this GC and
966 // wait until the GCLocker initiated GC is performed, and
967 // then retry the allocation.
968 if (GC_locker::needs_gc()) {
969 should_try_gc = false;
970 } else {
971 // Read the GC count while still holding the Heap_lock.
972 gc_count_before = total_collections();
973 should_try_gc = true;
974 }
975 }
976 }
977
978 if (should_try_gc) {
979 bool succeeded;
980 result = do_collection_pause(word_size, gc_count_before, &succeeded,
981 GCCause::_g1_inc_collection_pause);
982 if (result != NULL) {
983 assert(succeeded, "only way to get back a non-NULL result");
984 return result;
985 }
986
987 if (succeeded) {
988 // If we get here we successfully scheduled a collection which
989 // failed to allocate. No point in trying to allocate
990 // further. We'll just return NULL.
991 MutexLockerEx x(Heap_lock);
992 *gc_count_before_ret = total_collections();
993 return NULL;
994 }
995 } else {
996 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
997 MutexLockerEx x(Heap_lock);
998 *gc_count_before_ret = total_collections();
999 return NULL;
1000 }
1001 // The GCLocker is either active or the GCLocker initiated
1002 // GC has not yet been performed. Stall until it is and
1003 // then retry the allocation.
1004 GC_locker::stall_until_clear();
1005 (*gclocker_retry_count_ret) += 1;
1006 }
1007
1008 // We can reach here if we were unsuccessful in scheduling a
1009 // collection (because another thread beat us to it) or if we were
1010 // stalled due to the GC locker. In either can we should retry the
1011 // allocation attempt in case another thread successfully
1012 // performed a collection and reclaimed enough space. We do the
1013 // first attempt (without holding the Heap_lock) here and the
1014 // follow-on attempt will be at the start of the next loop
1015 // iteration (after taking the Heap_lock).
1016 result = _mutator_alloc_region.attempt_allocation(word_size,
1017 false /* bot_updates */);
1018 if (result != NULL) {
1019 return result;
1020 }
1021
1022 // Give a warning if we seem to be looping forever.
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_slow() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1035 unsigned int * gc_count_before_ret,
1036 int* gclocker_retry_count_ret) {
1037 // The structure of this method has a lot of similarities to
1038 // attempt_allocation_slow(). The reason these two were not merged
1039 // into a single one is that such a method would require several "if
1040 // allocation is not humongous do this, otherwise do that"
1041 // conditional paths which would obscure its flow. In fact, an early
1042 // version of this code did use a unified method which was harder to
1043 // follow and, as a result, it had subtle bugs that were hard to
1044 // track down. So keeping these two methods separate allows each to
1045 // be more readable. It will be good to keep these two in sync as
1046 // much as possible.
1047
1048 assert_heap_not_locked_and_not_at_safepoint();
1049 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1050 "should only be called for humongous allocations");
1051
1052 // Humongous objects can exhaust the heap quickly, so we should check if we
1053 // need to start a marking cycle at each humongous object allocation. We do
1054 // the check before we do the actual allocation. The reason for doing it
1055 // before the allocation is that we avoid having to keep track of the newly
1056 // allocated memory while we do a GC.
1057 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1058 word_size)) {
1059 collect(GCCause::_g1_humongous_allocation);
1060 }
1061
1062 // We will loop until a) we manage to successfully perform the
1063 // allocation or b) we successfully schedule a collection which
1064 // fails to perform the allocation. b) is the only case when we'll
1065 // return NULL.
1066 HeapWord* result = NULL;
1067 for (int try_count = 1; /* we'll return */; try_count += 1) {
1068 bool should_try_gc;
1069 unsigned int gc_count_before;
1070
1071 {
1072 MutexLockerEx x(Heap_lock);
1073
1074 // Given that humongous objects are not allocated in young
1075 // regions, we'll first try to do the allocation without doing a
1076 // collection hoping that there's enough space in the heap.
1077 result = humongous_obj_allocate(word_size);
1078 if (result != NULL) {
1079 return result;
1080 }
1081
1082 if (GC_locker::is_active_and_needs_gc()) {
1083 should_try_gc = false;
1084 } else {
1085 // The GCLocker may not be active but the GCLocker initiated
1086 // GC may not yet have been performed (GCLocker::needs_gc()
1087 // returns true). In this case we do not try this GC and
1088 // wait until the GCLocker initiated GC is performed, and
1089 // then retry the allocation.
1090 if (GC_locker::needs_gc()) {
1091 should_try_gc = false;
1092 } else {
1093 // Read the GC count while still holding the Heap_lock.
1094 gc_count_before = total_collections();
1095 should_try_gc = true;
1096 }
1097 }
1098 }
1099
1100 if (should_try_gc) {
1101 // If we failed to allocate the humongous object, we should try to
1102 // do a collection pause (if we're allowed) in case it reclaims
1103 // enough space for the allocation to succeed after the pause.
1104
1105 bool succeeded;
1106 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1107 GCCause::_g1_humongous_allocation);
1108 if (result != NULL) {
1109 assert(succeeded, "only way to get back a non-NULL result");
1110 return result;
1111 }
1112
1113 if (succeeded) {
1114 // If we get here we successfully scheduled a collection which
1115 // failed to allocate. No point in trying to allocate
1116 // further. We'll just return NULL.
1117 MutexLockerEx x(Heap_lock);
1118 *gc_count_before_ret = total_collections();
1119 return NULL;
1120 }
1121 } else {
1122 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1123 MutexLockerEx x(Heap_lock);
1124 *gc_count_before_ret = total_collections();
1125 return NULL;
1126 }
1127 // The GCLocker is either active or the GCLocker initiated
1128 // GC has not yet been performed. Stall until it is and
1129 // then retry the allocation.
1130 GC_locker::stall_until_clear();
1131 (*gclocker_retry_count_ret) += 1;
1132 }
1133
1134 // We can reach here if we were unsuccessful in scheduling a
1135 // collection (because another thread beat us to it) or if we were
1136 // stalled due to the GC locker. In either can we should retry the
1137 // allocation attempt in case another thread successfully
1138 // performed a collection and reclaimed enough space. Give a
1139 // warning if we seem to be looping forever.
1140
1141 if ((QueuedAllocationWarningCount > 0) &&
1142 (try_count % QueuedAllocationWarningCount == 0)) {
1143 warning("G1CollectedHeap::attempt_allocation_humongous() "
1144 "retries %d times", try_count);
1145 }
1146 }
1147
1148 ShouldNotReachHere();
1149 return NULL;
1150 }
1151
1152 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1153 bool expect_null_mutator_alloc_region) {
1154 assert_at_safepoint(true /* should_be_vm_thread */);
1155 assert(_mutator_alloc_region.get() == NULL ||
1156 !expect_null_mutator_alloc_region,
1157 "the current alloc region was unexpectedly found to be non-NULL");
1158
1159 if (!isHumongous(word_size)) {
1160 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1161 false /* bot_updates */);
1162 } else {
1163 HeapWord* result = humongous_obj_allocate(word_size);
1164 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1165 g1_policy()->set_initiate_conc_mark_if_possible();
1166 }
1167 return result;
1168 }
1169
1170 ShouldNotReachHere();
1171 }
1172
1173 class PostMCRemSetClearClosure: public HeapRegionClosure {
1174 G1CollectedHeap* _g1h;
1175 ModRefBarrierSet* _mr_bs;
1176 public:
1177 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1178 _g1h(g1h), _mr_bs(mr_bs) {}
1179
1180 bool doHeapRegion(HeapRegion* r) {
1181 HeapRegionRemSet* hrrs = r->rem_set();
1182
1183 if (r->continuesHumongous()) {
1184 // We'll assert that the strong code root list and RSet is empty
1185 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1186 assert(hrrs->occupied() == 0, "RSet should be empty");
1187 return false;
1188 }
1189
1190 _g1h->reset_gc_time_stamps(r);
1191 hrrs->clear();
1192 // You might think here that we could clear just the cards
1193 // corresponding to the used region. But no: if we leave a dirty card
1194 // in a region we might allocate into, then it would prevent that card
1195 // from being enqueued, and cause it to be missed.
1196 // Re: the performance cost: we shouldn't be doing full GC anyway!
1197 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1198
1199 return false;
1200 }
1201 };
1202
1203 void G1CollectedHeap::clear_rsets_post_compaction() {
1204 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1205 heap_region_iterate(&rs_clear);
1206 }
1207
1208 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1209 G1CollectedHeap* _g1h;
1210 UpdateRSOopClosure _cl;
1211 int _worker_i;
1212 public:
1213 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1214 _cl(g1->g1_rem_set(), worker_i),
1215 _worker_i(worker_i),
1216 _g1h(g1)
1217 { }
1218
1219 bool doHeapRegion(HeapRegion* r) {
1220 if (!r->continuesHumongous()) {
1221 _cl.set_from(r);
1222 r->oop_iterate(&_cl);
1223 }
1224 return false;
1225 }
1226 };
1227
1228 class ParRebuildRSTask: public AbstractGangTask {
1229 G1CollectedHeap* _g1;
1230 public:
1231 ParRebuildRSTask(G1CollectedHeap* g1)
1232 : AbstractGangTask("ParRebuildRSTask"),
1233 _g1(g1)
1234 { }
1235
1236 void work(uint worker_id) {
1237 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1238 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1239 _g1->workers()->active_workers(),
1240 HeapRegion::RebuildRSClaimValue);
1241 }
1242 };
1243
1244 class PostCompactionPrinterClosure: public HeapRegionClosure {
1245 private:
1246 G1HRPrinter* _hr_printer;
1247 public:
1248 bool doHeapRegion(HeapRegion* hr) {
1249 assert(!hr->is_young(), "not expecting to find young regions");
1250 // We only generate output for non-empty regions.
1251 if (!hr->is_empty()) {
1252 if (!hr->isHumongous()) {
1253 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1254 } else if (hr->startsHumongous()) {
1255 if (hr->region_num() == 1) {
1256 // single humongous region
1257 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1258 } else {
1259 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1260 }
1261 } else {
1262 assert(hr->continuesHumongous(), "only way to get here");
1263 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1264 }
1265 }
1266 return false;
1267 }
1268
1269 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1270 : _hr_printer(hr_printer) { }
1271 };
1272
1273 void G1CollectedHeap::print_hrs_post_compaction() {
1274 PostCompactionPrinterClosure cl(hr_printer());
1275 heap_region_iterate(&cl);
1276 }
1277
1278 bool G1CollectedHeap::do_collection(bool explicit_gc,
1279 bool clear_all_soft_refs,
1280 size_t word_size) {
1281 assert_at_safepoint(true /* should_be_vm_thread */);
1282
1283 if (GC_locker::check_active_before_gc()) {
1284 return false;
1285 }
1286
1287 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1288 gc_timer->register_gc_start();
1289
1290 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1291 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1292
1293 SvcGCMarker sgcm(SvcGCMarker::FULL);
1294 ResourceMark rm;
1295
1296 print_heap_before_gc();
1297 trace_heap_before_gc(gc_tracer);
1298
1299 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1300
1301 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 // Include the current allocation, if any, and bytes that will be
1579 // pre-allocated to support collections, as "used".
1580 const size_t used_after_gc = used();
1581 const size_t capacity_after_gc = capacity();
1582 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1583
1584 // This is enforced in arguments.cpp.
1585 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1586 "otherwise the code below doesn't make sense");
1587
1588 // We don't have floating point command-line arguments
1589 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1590 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1591 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1592 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1593
1594 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1595 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1596
1597 // We have to be careful here as these two calculations can overflow
1598 // 32-bit size_t's.
1599 double used_after_gc_d = (double) used_after_gc;
1600 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1601 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1602
1603 // Let's make sure that they are both under the max heap size, which
1604 // by default will make them fit into a size_t.
1605 double desired_capacity_upper_bound = (double) max_heap_size;
1606 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1607 desired_capacity_upper_bound);
1608 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1609 desired_capacity_upper_bound);
1610
1611 // We can now safely turn them into size_t's.
1612 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1613 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1614
1615 // This assert only makes sense here, before we adjust them
1616 // with respect to the min and max heap size.
1617 assert(minimum_desired_capacity <= maximum_desired_capacity,
1618 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1619 "maximum_desired_capacity = "SIZE_FORMAT,
1620 minimum_desired_capacity, maximum_desired_capacity));
1621
1622 // Should not be greater than the heap max size. No need to adjust
1623 // it with respect to the heap min size as it's a lower bound (i.e.,
1624 // we'll try to make the capacity larger than it, not smaller).
1625 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1626 // Should not be less than the heap min size. No need to adjust it
1627 // with respect to the heap max size as it's an upper bound (i.e.,
1628 // we'll try to make the capacity smaller than it, not greater).
1629 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1630
1631 if (capacity_after_gc < minimum_desired_capacity) {
1632 // Don't expand unless it's significant
1633 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1634 ergo_verbose4(ErgoHeapSizing,
1635 "attempt heap expansion",
1636 ergo_format_reason("capacity lower than "
1637 "min desired capacity after Full GC")
1638 ergo_format_byte("capacity")
1639 ergo_format_byte("occupancy")
1640 ergo_format_byte_perc("min desired capacity"),
1641 capacity_after_gc, used_after_gc,
1642 minimum_desired_capacity, (double) MinHeapFreeRatio);
1643 expand(expand_bytes);
1644
1645 // No expansion, now see if we want to shrink
1646 } else if (capacity_after_gc > maximum_desired_capacity) {
1647 // Capacity too large, compute shrinking size
1648 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1649 ergo_verbose4(ErgoHeapSizing,
1650 "attempt heap shrinking",
1651 ergo_format_reason("capacity higher than "
1652 "max desired capacity after Full GC")
1653 ergo_format_byte("capacity")
1654 ergo_format_byte("occupancy")
1655 ergo_format_byte_perc("max desired capacity"),
1656 capacity_after_gc, used_after_gc,
1657 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1658 shrink(shrink_bytes);
1659 }
1660 }
1661
1662
1663 HeapWord*
1664 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1665 bool* succeeded) {
1666 assert_at_safepoint(true /* should_be_vm_thread */);
1667
1668 *succeeded = true;
1669 // Let's attempt the allocation first.
1670 HeapWord* result =
1671 attempt_allocation_at_safepoint(word_size,
1672 false /* expect_null_mutator_alloc_region */);
1673 if (result != NULL) {
1674 assert(*succeeded, "sanity");
1675 return result;
1676 }
1677
1678 // In a G1 heap, we're supposed to keep allocation from failing by
1679 // incremental pauses. Therefore, at least for now, we'll favor
1680 // expansion over collection. (This might change in the future if we can
1681 // do something smarter than full collection to satisfy a failed alloc.)
1682 result = expand_and_allocate(word_size);
1683 if (result != NULL) {
1684 assert(*succeeded, "sanity");
1685 return result;
1686 }
1687
1688 // Expansion didn't work, we'll try to do a Full GC.
1689 bool gc_succeeded = do_collection(false, /* explicit_gc */
1690 false, /* clear_all_soft_refs */
1691 word_size);
1692 if (!gc_succeeded) {
1693 *succeeded = false;
1694 return NULL;
1695 }
1696
1697 // Retry the allocation
1698 result = attempt_allocation_at_safepoint(word_size,
1699 true /* expect_null_mutator_alloc_region */);
1700 if (result != NULL) {
1701 assert(*succeeded, "sanity");
1702 return result;
1703 }
1704
1705 // Then, try a Full GC that will collect all soft references.
1706 gc_succeeded = do_collection(false, /* explicit_gc */
1707 true, /* clear_all_soft_refs */
1708 word_size);
1709 if (!gc_succeeded) {
1710 *succeeded = false;
1711 return NULL;
1712 }
1713
1714 // Retry the allocation once more
1715 result = attempt_allocation_at_safepoint(word_size,
1716 true /* expect_null_mutator_alloc_region */);
1717 if (result != NULL) {
1718 assert(*succeeded, "sanity");
1719 return result;
1720 }
1721
1722 assert(!collector_policy()->should_clear_all_soft_refs(),
1723 "Flag should have been handled and cleared prior to this point");
1724
1725 // What else? We might try synchronous finalization later. If the total
1726 // space available is large enough for the allocation, then a more
1727 // complete compaction phase than we've tried so far might be
1728 // appropriate.
1729 assert(*succeeded, "sanity");
1730 return NULL;
1731 }
1732
1733 // Attempting to expand the heap sufficiently
1734 // to support an allocation of the given "word_size". If
1735 // successful, perform the allocation and return the address of the
1736 // allocated block, or else "NULL".
1737
1738 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1739 assert_at_safepoint(true /* should_be_vm_thread */);
1740
1741 verify_region_sets_optional();
1742
1743 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1744 ergo_verbose1(ErgoHeapSizing,
1745 "attempt heap expansion",
1746 ergo_format_reason("allocation request failed")
1747 ergo_format_byte("allocation request"),
1748 word_size * HeapWordSize);
1749 if (expand(expand_bytes)) {
1750 _hrs.verify_optional();
1751 verify_region_sets_optional();
1752 return attempt_allocation_at_safepoint(word_size,
1753 false /* expect_null_mutator_alloc_region */);
1754 }
1755 return NULL;
1756 }
1757
1758 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1759 HeapWord* new_end) {
1760 assert(old_end != new_end, "don't call this otherwise");
1761 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1762
1763 // Update the committed mem region.
1764 _g1_committed.set_end(new_end);
1765 // Tell the card table about the update.
1766 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1767 // Tell the BOT about the update.
1768 _bot_shared->resize(_g1_committed.word_size());
1769 // Tell the hot card cache about the update
1770 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1771 }
1772
1773 bool G1CollectedHeap::expand(size_t expand_bytes) {
1774 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1775 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1776 HeapRegion::GrainBytes);
1777 ergo_verbose2(ErgoHeapSizing,
1778 "expand the heap",
1779 ergo_format_byte("requested expansion amount")
1780 ergo_format_byte("attempted expansion amount"),
1781 expand_bytes, aligned_expand_bytes);
1782
1783 if (_g1_storage.uncommitted_size() == 0) {
1784 ergo_verbose0(ErgoHeapSizing,
1785 "did not expand the heap",
1786 ergo_format_reason("heap already fully expanded"));
1787 return false;
1788 }
1789
1790 // First commit the memory.
1791 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1792 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1793 if (successful) {
1794 // Then propagate this update to the necessary data structures.
1795 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1796 update_committed_space(old_end, new_end);
1797
1798 FreeRegionList expansion_list("Local Expansion List");
1799 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1800 assert(mr.start() == old_end, "post-condition");
1801 // mr might be a smaller region than what was requested if
1802 // expand_by() was unable to allocate the HeapRegion instances
1803 assert(mr.end() <= new_end, "post-condition");
1804
1805 size_t actual_expand_bytes = mr.byte_size();
1806 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1807 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1808 "post-condition");
1809 if (actual_expand_bytes < aligned_expand_bytes) {
1810 // We could not expand _hrs to the desired size. In this case we
1811 // need to shrink the committed space accordingly.
1812 assert(mr.end() < new_end, "invariant");
1813
1814 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1815 // First uncommit the memory.
1816 _g1_storage.shrink_by(diff_bytes);
1817 // Then propagate this update to the necessary data structures.
1818 update_committed_space(new_end, mr.end());
1819 }
1820 _free_list.add_as_tail(&expansion_list);
1821
1822 if (_hr_printer.is_active()) {
1823 HeapWord* curr = mr.start();
1824 while (curr < mr.end()) {
1825 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1826 _hr_printer.commit(curr, curr_end);
1827 curr = curr_end;
1828 }
1829 assert(curr == mr.end(), "post-condition");
1830 }
1831 g1_policy()->record_new_heap_size(n_regions());
1832 } else {
1833 ergo_verbose0(ErgoHeapSizing,
1834 "did not expand the heap",
1835 ergo_format_reason("heap expansion operation failed"));
1836 // The expansion of the virtual storage space was unsuccessful.
1837 // Let's see if it was because we ran out of swap.
1838 if (G1ExitOnExpansionFailure &&
1839 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1840 // We had head room...
1841 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1842 }
1843 }
1844 return successful;
1845 }
1846
1847 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1848 size_t aligned_shrink_bytes =
1849 ReservedSpace::page_align_size_down(shrink_bytes);
1850 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1851 HeapRegion::GrainBytes);
1852 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1853
1854 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1855 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1856 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1857
1858 ergo_verbose3(ErgoHeapSizing,
1859 "shrink the heap",
1860 ergo_format_byte("requested shrinking amount")
1861 ergo_format_byte("aligned shrinking amount")
1862 ergo_format_byte("attempted shrinking amount"),
1863 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1864 if (num_regions_removed > 0) {
1865 _g1_storage.shrink_by(shrunk_bytes);
1866 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1867
1868 if (_hr_printer.is_active()) {
1869 HeapWord* curr = old_end;
1870 while (curr > new_end) {
1871 HeapWord* curr_end = curr;
1872 curr -= HeapRegion::GrainWords;
1873 _hr_printer.uncommit(curr, curr_end);
1874 }
1875 }
1876
1877 _expansion_regions += num_regions_removed;
1878 update_committed_space(old_end, new_end);
1879 HeapRegionRemSet::shrink_heap(n_regions());
1880 g1_policy()->record_new_heap_size(n_regions());
1881 } else {
1882 ergo_verbose0(ErgoHeapSizing,
1883 "did not shrink the heap",
1884 ergo_format_reason("heap shrinking operation failed"));
1885 }
1886 }
1887
1888 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1889 verify_region_sets_optional();
1890
1891 // We should only reach here at the end of a Full GC which means we
1892 // should not not be holding to any GC alloc regions. The method
1893 // below will make sure of that and do any remaining clean up.
1894 abandon_gc_alloc_regions();
1895
1896 // Instead of tearing down / rebuilding the free lists here, we
1897 // could instead use the remove_all_pending() method on free_list to
1898 // remove only the ones that we need to remove.
1899 tear_down_region_sets(true /* free_list_only */);
1900 shrink_helper(shrink_bytes);
1901 rebuild_region_sets(true /* free_list_only */);
1902
1903 _hrs.verify_optional();
1904 verify_region_sets_optional();
1905 }
1906
1907 // Public methods.
1908
1909 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1910 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1911 #endif // _MSC_VER
1912
1913
1914 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1915 SharedHeap(policy_),
1916 _g1_policy(policy_),
1917 _dirty_card_queue_set(false),
1918 _into_cset_dirty_card_queue_set(false),
1919 _is_alive_closure_cm(this),
1920 _is_alive_closure_stw(this),
1921 _ref_processor_cm(NULL),
1922 _ref_processor_stw(NULL),
1923 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1924 _bot_shared(NULL),
1925 _evac_failure_scan_stack(NULL),
1926 _mark_in_progress(false),
1927 _cg1r(NULL), _summary_bytes_used(0),
1928 _g1mm(NULL),
1929 _refine_cte_cl(NULL),
1930 _full_collection(false),
1931 _free_list("Master Free List"),
1932 _secondary_free_list("Secondary Free List"),
1933 _old_set("Old Set"),
1934 _humongous_set("Master Humongous Set"),
1935 _free_regions_coming(false),
1936 _young_list(new YoungList(this)),
1937 _gc_time_stamp(0),
1938 _retained_old_gc_alloc_region(NULL),
1939 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1940 _old_plab_stats(OldPLABSize, PLABWeight),
1941 _expand_heap_after_alloc_failure(true),
1942 _surviving_young_words(NULL),
1943 _old_marking_cycles_started(0),
1944 _old_marking_cycles_completed(0),
1945 _concurrent_cycle_started(false),
1946 _in_cset_fast_test(NULL),
1947 _in_cset_fast_test_base(NULL),
1948 _dirty_cards_region_list(NULL),
1949 _worker_cset_start_region(NULL),
1950 _worker_cset_start_region_time_stamp(NULL),
1951 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1952 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1953 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1954 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1955
1956 _g1h = this;
1957 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1958 vm_exit_during_initialization("Failed necessary allocation.");
1959 }
1960
1961 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1962
1963 int n_queues = MAX2((int)ParallelGCThreads, 1);
1964 _task_queues = new RefToScanQueueSet(n_queues);
1965
1966 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1967 assert(n_rem_sets > 0, "Invariant.");
1968
1969 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1970 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1971 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1972
1973 for (int i = 0; i < n_queues; i++) {
1974 RefToScanQueue* q = new RefToScanQueue();
1975 q->initialize();
1976 _task_queues->register_queue(i, q);
1977 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1978 }
1979 clear_cset_start_regions();
1980
1981 // Initialize the G1EvacuationFailureALot counters and flags.
1982 NOT_PRODUCT(reset_evacuation_should_fail();)
1983
1984 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1985 }
1986
1987 jint G1CollectedHeap::initialize() {
1988 CollectedHeap::pre_initialize();
1989 os::enable_vtime();
1990
1991 G1Log::init();
1992
1993 // Necessary to satisfy locking discipline assertions.
1994
1995 MutexLocker x(Heap_lock);
1996
1997 // We have to initialize the printer before committing the heap, as
1998 // it will be used then.
1999 _hr_printer.set_active(G1PrintHeapRegions);
2000
2001 // While there are no constraints in the GC code that HeapWordSize
2002 // be any particular value, there are multiple other areas in the
2003 // system which believe this to be true (e.g. oop->object_size in some
2004 // cases incorrectly returns the size in wordSize units rather than
2005 // HeapWordSize).
2006 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2007
2008 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2009 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2010 size_t heap_alignment = collector_policy()->heap_alignment();
2011
2012 // Ensure that the sizes are properly aligned.
2013 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2014 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2015 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2016
2017 _cg1r = new ConcurrentG1Refine(this);
2018
2019 // Reserve the maximum.
2020
2021 // When compressed oops are enabled, the preferred heap base
2022 // is calculated by subtracting the requested size from the
2023 // 32Gb boundary and using the result as the base address for
2024 // heap reservation. If the requested size is not aligned to
2025 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2026 // into the ReservedHeapSpace constructor) then the actual
2027 // base of the reserved heap may end up differing from the
2028 // address that was requested (i.e. the preferred heap base).
2029 // If this happens then we could end up using a non-optimal
2030 // compressed oops mode.
2031
2032 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2033 heap_alignment);
2034
2035 // It is important to do this in a way such that concurrent readers can't
2036 // temporarily think something is in the heap. (I've actually seen this
2037 // happen in asserts: DLD.)
2038 _reserved.set_word_size(0);
2039 _reserved.set_start((HeapWord*)heap_rs.base());
2040 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2041
2042 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2043
2044 // Create the gen rem set (and barrier set) for the entire reserved region.
2045 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2046 set_barrier_set(rem_set()->bs());
2047 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2048 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2049 return JNI_ENOMEM;
2050 }
2051
2052 // Also create a G1 rem set.
2053 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2054
2055 // Carve out the G1 part of the heap.
2056
2057 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2058 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2059 g1_rs.size()/HeapWordSize);
2060
2061 _g1_storage.initialize(g1_rs, 0);
2062 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2063 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2064 (HeapWord*) _g1_reserved.end());
2065 assert(_hrs.max_length() == _expansion_regions,
2066 err_msg("max length: %u expansion regions: %u",
2067 _hrs.max_length(), _expansion_regions));
2068
2069 // Do later initialization work for concurrent refinement.
2070 _cg1r->init();
2071
2072 // 6843694 - ensure that the maximum region index can fit
2073 // in the remembered set structures.
2074 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2075 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2076
2077 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2078 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2079 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2080 "too many cards per region");
2081
2082 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2083
2084 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2085 heap_word_size(init_byte_size));
2086
2087 _g1h = this;
2088
2089 _in_cset_fast_test_length = max_regions();
2090 _in_cset_fast_test_base =
2091 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2092
2093 // We're biasing _in_cset_fast_test to avoid subtracting the
2094 // beginning of the heap every time we want to index; basically
2095 // it's the same with what we do with the card table.
2096 _in_cset_fast_test = _in_cset_fast_test_base -
2097 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2098
2099 // Clear the _cset_fast_test bitmap in anticipation of adding
2100 // regions to the incremental collection set for the first
2101 // evacuation pause.
2102 clear_cset_fast_test();
2103
2104 // Create the ConcurrentMark data structure and thread.
2105 // (Must do this late, so that "max_regions" is defined.)
2106 _cm = new ConcurrentMark(this, heap_rs);
2107 if (_cm == NULL || !_cm->completed_initialization()) {
2108 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2109 return JNI_ENOMEM;
2110 }
2111 _cmThread = _cm->cmThread();
2112
2113 // Initialize the from_card cache structure of HeapRegionRemSet.
2114 HeapRegionRemSet::init_heap(max_regions());
2115
2116 // Now expand into the initial heap size.
2117 if (!expand(init_byte_size)) {
2118 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2119 return JNI_ENOMEM;
2120 }
2121
2122 // Perform any initialization actions delegated to the policy.
2123 g1_policy()->init();
2124
2125 _refine_cte_cl =
2126 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2127 g1_rem_set(),
2128 concurrent_g1_refine());
2129 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2130
2131 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2132 SATB_Q_FL_lock,
2133 G1SATBProcessCompletedThreshold,
2134 Shared_SATB_Q_lock);
2135
2136 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2137 DirtyCardQ_FL_lock,
2138 concurrent_g1_refine()->yellow_zone(),
2139 concurrent_g1_refine()->red_zone(),
2140 Shared_DirtyCardQ_lock);
2141
2142 if (G1DeferredRSUpdate) {
2143 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2144 DirtyCardQ_FL_lock,
2145 -1, // never trigger processing
2146 -1, // no limit on length
2147 Shared_DirtyCardQ_lock,
2148 &JavaThread::dirty_card_queue_set());
2149 }
2150
2151 // Initialize the card queue set used to hold cards containing
2152 // references into the collection set.
2153 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2154 DirtyCardQ_FL_lock,
2155 -1, // never trigger processing
2156 -1, // no limit on length
2157 Shared_DirtyCardQ_lock,
2158 &JavaThread::dirty_card_queue_set());
2159
2160 // In case we're keeping closure specialization stats, initialize those
2161 // counts and that mechanism.
2162 SpecializationStats::clear();
2163
2164 // Here we allocate the dummy full region that is required by the
2165 // G1AllocRegion class. If we don't pass an address in the reserved
2166 // space here, lots of asserts fire.
2167
2168 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2169 _g1_reserved.start());
2170 // We'll re-use the same region whether the alloc region will
2171 // require BOT updates or not and, if it doesn't, then a non-young
2172 // region will complain that it cannot support allocations without
2173 // BOT updates. So we'll tag the dummy region as young to avoid that.
2174 dummy_region->set_young();
2175 // Make sure it's full.
2176 dummy_region->set_top(dummy_region->end());
2177 G1AllocRegion::setup(this, dummy_region);
2178
2179 init_mutator_alloc_region();
2180
2181 // Do create of the monitoring and management support so that
2182 // values in the heap have been properly initialized.
2183 _g1mm = new G1MonitoringSupport(this);
2184
2185 return JNI_OK;
2186 }
2187
2188 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2189 return HeapRegion::max_region_size();
2190 }
2191
2192 void G1CollectedHeap::ref_processing_init() {
2193 // Reference processing in G1 currently works as follows:
2194 //
2195 // * There are two reference processor instances. One is
2196 // used to record and process discovered references
2197 // during concurrent marking; the other is used to
2198 // record and process references during STW pauses
2199 // (both full and incremental).
2200 // * Both ref processors need to 'span' the entire heap as
2201 // the regions in the collection set may be dotted around.
2202 //
2203 // * For the concurrent marking ref processor:
2204 // * Reference discovery is enabled at initial marking.
2205 // * Reference discovery is disabled and the discovered
2206 // references processed etc during remarking.
2207 // * Reference discovery is MT (see below).
2208 // * Reference discovery requires a barrier (see below).
2209 // * Reference processing may or may not be MT
2210 // (depending on the value of ParallelRefProcEnabled
2211 // and ParallelGCThreads).
2212 // * A full GC disables reference discovery by the CM
2213 // ref processor and abandons any entries on it's
2214 // discovered lists.
2215 //
2216 // * For the STW processor:
2217 // * Non MT discovery is enabled at the start of a full GC.
2218 // * Processing and enqueueing during a full GC is non-MT.
2219 // * During a full GC, references are processed after marking.
2220 //
2221 // * Discovery (may or may not be MT) is enabled at the start
2222 // of an incremental evacuation pause.
2223 // * References are processed near the end of a STW evacuation pause.
2224 // * For both types of GC:
2225 // * Discovery is atomic - i.e. not concurrent.
2226 // * Reference discovery will not need a barrier.
2227
2228 SharedHeap::ref_processing_init();
2229 MemRegion mr = reserved_region();
2230
2231 // Concurrent Mark ref processor
2232 _ref_processor_cm =
2233 new ReferenceProcessor(mr, // span
2234 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2235 // mt processing
2236 (int) ParallelGCThreads,
2237 // degree of mt processing
2238 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2239 // mt discovery
2240 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2241 // degree of mt discovery
2242 false,
2243 // Reference discovery is not atomic
2244 &_is_alive_closure_cm,
2245 // is alive closure
2246 // (for efficiency/performance)
2247 true);
2248 // Setting next fields of discovered
2249 // lists requires a barrier.
2250
2251 // STW ref processor
2252 _ref_processor_stw =
2253 new ReferenceProcessor(mr, // span
2254 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2255 // mt processing
2256 MAX2((int)ParallelGCThreads, 1),
2257 // degree of mt processing
2258 (ParallelGCThreads > 1),
2259 // mt discovery
2260 MAX2((int)ParallelGCThreads, 1),
2261 // degree of mt discovery
2262 true,
2263 // Reference discovery is atomic
2264 &_is_alive_closure_stw,
2265 // is alive closure
2266 // (for efficiency/performance)
2267 false);
2268 // Setting next fields of discovered
2269 // lists requires a barrier.
2270 }
2271
2272 size_t G1CollectedHeap::capacity() const {
2273 return _g1_committed.byte_size();
2274 }
2275
2276 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2277 assert(!hr->continuesHumongous(), "pre-condition");
2278 hr->reset_gc_time_stamp();
2279 if (hr->startsHumongous()) {
2280 uint first_index = hr->hrs_index() + 1;
2281 uint last_index = hr->last_hc_index();
2282 for (uint i = first_index; i < last_index; i += 1) {
2283 HeapRegion* chr = region_at(i);
2284 assert(chr->continuesHumongous(), "sanity");
2285 chr->reset_gc_time_stamp();
2286 }
2287 }
2288 }
2289
2290 #ifndef PRODUCT
2291 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2292 private:
2293 unsigned _gc_time_stamp;
2294 bool _failures;
2295
2296 public:
2297 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2298 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2299
2300 virtual bool doHeapRegion(HeapRegion* hr) {
2301 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2302 if (_gc_time_stamp != region_gc_time_stamp) {
2303 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2304 "expected %d", HR_FORMAT_PARAMS(hr),
2305 region_gc_time_stamp, _gc_time_stamp);
2306 _failures = true;
2307 }
2308 return false;
2309 }
2310
2311 bool failures() { return _failures; }
2312 };
2313
2314 void G1CollectedHeap::check_gc_time_stamps() {
2315 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2316 heap_region_iterate(&cl);
2317 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2318 }
2319 #endif // PRODUCT
2320
2321 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2322 DirtyCardQueue* into_cset_dcq,
2323 bool concurrent,
2324 int worker_i) {
2325 // Clean cards in the hot card cache
2326 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2327 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2328
2329 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2330 int n_completed_buffers = 0;
2331 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2332 n_completed_buffers++;
2333 }
2334 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2335 dcqs.clear_n_completed_buffers();
2336 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2337 }
2338
2339
2340 // Computes the sum of the storage used by the various regions.
2341
2342 size_t G1CollectedHeap::used() const {
2343 assert(Heap_lock->owner() != NULL,
2344 "Should be owned on this thread's behalf.");
2345 size_t result = _summary_bytes_used;
2346 // Read only once in case it is set to NULL concurrently
2347 HeapRegion* hr = _mutator_alloc_region.get();
2348 if (hr != NULL)
2349 result += hr->used();
2350 return result;
2351 }
2352
2353 size_t G1CollectedHeap::used_unlocked() const {
2354 size_t result = _summary_bytes_used;
2355 return result;
2356 }
2357
2358 class SumUsedClosure: public HeapRegionClosure {
2359 size_t _used;
2360 public:
2361 SumUsedClosure() : _used(0) {}
2362 bool doHeapRegion(HeapRegion* r) {
2363 if (!r->continuesHumongous()) {
2364 _used += r->used();
2365 }
2366 return false;
2367 }
2368 size_t result() { return _used; }
2369 };
2370
2371 size_t G1CollectedHeap::recalculate_used() const {
2372 SumUsedClosure blk;
2373 heap_region_iterate(&blk);
2374 return blk.result();
2375 }
2376
2377 size_t G1CollectedHeap::unsafe_max_alloc() {
2378 if (free_regions() > 0) return HeapRegion::GrainBytes;
2379 // otherwise, is there space in the current allocation region?
2380
2381 // We need to store the current allocation region in a local variable
2382 // here. The problem is that this method doesn't take any locks and
2383 // there may be other threads which overwrite the current allocation
2384 // region field. attempt_allocation(), for example, sets it to NULL
2385 // and this can happen *after* the NULL check here but before the call
2386 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2387 // to be a problem in the optimized build, since the two loads of the
2388 // current allocation region field are optimized away.
2389 HeapRegion* hr = _mutator_alloc_region.get();
2390 if (hr == NULL) {
2391 return 0;
2392 }
2393 return hr->free();
2394 }
2395
2396 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2397 switch (cause) {
2398 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2399 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2400 case GCCause::_g1_humongous_allocation: return true;
2401 default: return false;
2402 }
2403 }
2404
2405 #ifndef PRODUCT
2406 void G1CollectedHeap::allocate_dummy_regions() {
2407 // Let's fill up most of the region
2408 size_t word_size = HeapRegion::GrainWords - 1024;
2409 // And as a result the region we'll allocate will be humongous.
2410 guarantee(isHumongous(word_size), "sanity");
2411
2412 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2413 // Let's use the existing mechanism for the allocation
2414 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2415 if (dummy_obj != NULL) {
2416 MemRegion mr(dummy_obj, word_size);
2417 CollectedHeap::fill_with_object(mr);
2418 } else {
2419 // If we can't allocate once, we probably cannot allocate
2420 // again. Let's get out of the loop.
2421 break;
2422 }
2423 }
2424 }
2425 #endif // !PRODUCT
2426
2427 void G1CollectedHeap::increment_old_marking_cycles_started() {
2428 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2429 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2430 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2431 _old_marking_cycles_started, _old_marking_cycles_completed));
2432
2433 _old_marking_cycles_started++;
2434 }
2435
2436 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2437 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2438
2439 // We assume that if concurrent == true, then the caller is a
2440 // concurrent thread that was joined the Suspendible Thread
2441 // Set. If there's ever a cheap way to check this, we should add an
2442 // assert here.
2443
2444 // Given that this method is called at the end of a Full GC or of a
2445 // concurrent cycle, and those can be nested (i.e., a Full GC can
2446 // interrupt a concurrent cycle), the number of full collections
2447 // completed should be either one (in the case where there was no
2448 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2449 // behind the number of full collections started.
2450
2451 // This is the case for the inner caller, i.e. a Full GC.
2452 assert(concurrent ||
2453 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2454 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2455 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2456 "is inconsistent with _old_marking_cycles_completed = %u",
2457 _old_marking_cycles_started, _old_marking_cycles_completed));
2458
2459 // This is the case for the outer caller, i.e. the concurrent cycle.
2460 assert(!concurrent ||
2461 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2462 err_msg("for outer caller (concurrent cycle): "
2463 "_old_marking_cycles_started = %u "
2464 "is inconsistent with _old_marking_cycles_completed = %u",
2465 _old_marking_cycles_started, _old_marking_cycles_completed));
2466
2467 _old_marking_cycles_completed += 1;
2468
2469 // We need to clear the "in_progress" flag in the CM thread before
2470 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2471 // is set) so that if a waiter requests another System.gc() it doesn't
2472 // incorrectly see that a marking cycle is still in progress.
2473 if (concurrent) {
2474 _cmThread->clear_in_progress();
2475 }
2476
2477 // This notify_all() will ensure that a thread that called
2478 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2479 // and it's waiting for a full GC to finish will be woken up. It is
2480 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2481 FullGCCount_lock->notify_all();
2482 }
2483
2484 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2485 _concurrent_cycle_started = true;
2486 _gc_timer_cm->register_gc_start(start_time);
2487
2488 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2489 trace_heap_before_gc(_gc_tracer_cm);
2490 }
2491
2492 void G1CollectedHeap::register_concurrent_cycle_end() {
2493 if (_concurrent_cycle_started) {
2494 if (_cm->has_aborted()) {
2495 _gc_tracer_cm->report_concurrent_mode_failure();
2496 }
2497
2498 _gc_timer_cm->register_gc_end();
2499 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2500
2501 _concurrent_cycle_started = false;
2502 }
2503 }
2504
2505 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2506 if (_concurrent_cycle_started) {
2507 trace_heap_after_gc(_gc_tracer_cm);
2508 }
2509 }
2510
2511 G1YCType G1CollectedHeap::yc_type() {
2512 bool is_young = g1_policy()->gcs_are_young();
2513 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2514 bool is_during_mark = mark_in_progress();
2515
2516 if (is_initial_mark) {
2517 return InitialMark;
2518 } else if (is_during_mark) {
2519 return DuringMark;
2520 } else if (is_young) {
2521 return Normal;
2522 } else {
2523 return Mixed;
2524 }
2525 }
2526
2527 void G1CollectedHeap::collect(GCCause::Cause cause) {
2528 assert_heap_not_locked();
2529
2530 unsigned int gc_count_before;
2531 unsigned int old_marking_count_before;
2532 bool retry_gc;
2533
2534 do {
2535 retry_gc = false;
2536
2537 {
2538 MutexLocker ml(Heap_lock);
2539
2540 // Read the GC count while holding the Heap_lock
2541 gc_count_before = total_collections();
2542 old_marking_count_before = _old_marking_cycles_started;
2543 }
2544
2545 if (should_do_concurrent_full_gc(cause)) {
2546 // Schedule an initial-mark evacuation pause that will start a
2547 // concurrent cycle. We're setting word_size to 0 which means that
2548 // we are not requesting a post-GC allocation.
2549 VM_G1IncCollectionPause op(gc_count_before,
2550 0, /* word_size */
2551 true, /* should_initiate_conc_mark */
2552 g1_policy()->max_pause_time_ms(),
2553 cause);
2554
2555 VMThread::execute(&op);
2556 if (!op.pause_succeeded()) {
2557 if (old_marking_count_before == _old_marking_cycles_started) {
2558 retry_gc = op.should_retry_gc();
2559 } else {
2560 // A Full GC happened while we were trying to schedule the
2561 // initial-mark GC. No point in starting a new cycle given
2562 // that the whole heap was collected anyway.
2563 }
2564
2565 if (retry_gc) {
2566 if (GC_locker::is_active_and_needs_gc()) {
2567 GC_locker::stall_until_clear();
2568 }
2569 }
2570 }
2571 } else {
2572 if (cause == GCCause::_gc_locker
2573 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2574
2575 // Schedule a standard evacuation pause. We're setting word_size
2576 // to 0 which means that we are not requesting a post-GC allocation.
2577 VM_G1IncCollectionPause op(gc_count_before,
2578 0, /* word_size */
2579 false, /* should_initiate_conc_mark */
2580 g1_policy()->max_pause_time_ms(),
2581 cause);
2582 VMThread::execute(&op);
2583 } else {
2584 // Schedule a Full GC.
2585 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2586 VMThread::execute(&op);
2587 }
2588 }
2589 } while (retry_gc);
2590 }
2591
2592 bool G1CollectedHeap::is_in(const void* p) const {
2593 if (_g1_committed.contains(p)) {
2594 // Given that we know that p is in the committed space,
2595 // heap_region_containing_raw() should successfully
2596 // return the containing region.
2597 HeapRegion* hr = heap_region_containing_raw(p);
2598 return hr->is_in(p);
2599 } else {
2600 return false;
2601 }
2602 }
2603
2604 // Iteration functions.
2605
2606 // Iterates an OopClosure over all ref-containing fields of objects
2607 // within a HeapRegion.
2608
2609 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2610 MemRegion _mr;
2611 ExtendedOopClosure* _cl;
2612 public:
2613 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2614 : _mr(mr), _cl(cl) {}
2615 bool doHeapRegion(HeapRegion* r) {
2616 if (!r->continuesHumongous()) {
2617 r->oop_iterate(_cl);
2618 }
2619 return false;
2620 }
2621 };
2622
2623 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2624 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2625 heap_region_iterate(&blk);
2626 }
2627
2628 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2629 IterateOopClosureRegionClosure blk(mr, cl);
2630 heap_region_iterate(&blk);
2631 }
2632
2633 // Iterates an ObjectClosure over all objects within a HeapRegion.
2634
2635 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2636 ObjectClosure* _cl;
2637 public:
2638 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2639 bool doHeapRegion(HeapRegion* r) {
2640 if (! r->continuesHumongous()) {
2641 r->object_iterate(_cl);
2642 }
2643 return false;
2644 }
2645 };
2646
2647 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2648 IterateObjectClosureRegionClosure blk(cl);
2649 heap_region_iterate(&blk);
2650 }
2651
2652 // Calls a SpaceClosure on a HeapRegion.
2653
2654 class SpaceClosureRegionClosure: public HeapRegionClosure {
2655 SpaceClosure* _cl;
2656 public:
2657 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2658 bool doHeapRegion(HeapRegion* r) {
2659 _cl->do_space(r);
2660 return false;
2661 }
2662 };
2663
2664 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2665 SpaceClosureRegionClosure blk(cl);
2666 heap_region_iterate(&blk);
2667 }
2668
2669 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2670 _hrs.iterate(cl);
2671 }
2672
2673 void
2674 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2675 uint worker_id,
2676 uint no_of_par_workers,
2677 jint claim_value) {
2678 const uint regions = n_regions();
2679 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2680 no_of_par_workers :
2681 1);
2682 assert(UseDynamicNumberOfGCThreads ||
2683 no_of_par_workers == workers()->total_workers(),
2684 "Non dynamic should use fixed number of workers");
2685 // try to spread out the starting points of the workers
2686 const HeapRegion* start_hr =
2687 start_region_for_worker(worker_id, no_of_par_workers);
2688 const uint start_index = start_hr->hrs_index();
2689
2690 // each worker will actually look at all regions
2691 for (uint count = 0; count < regions; ++count) {
2692 const uint index = (start_index + count) % regions;
2693 assert(0 <= index && index < regions, "sanity");
2694 HeapRegion* r = region_at(index);
2695 // we'll ignore "continues humongous" regions (we'll process them
2696 // when we come across their corresponding "start humongous"
2697 // region) and regions already claimed
2698 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2699 continue;
2700 }
2701 // OK, try to claim it
2702 if (r->claimHeapRegion(claim_value)) {
2703 // success!
2704 assert(!r->continuesHumongous(), "sanity");
2705 if (r->startsHumongous()) {
2706 // If the region is "starts humongous" we'll iterate over its
2707 // "continues humongous" first; in fact we'll do them
2708 // first. The order is important. In on case, calling the
2709 // closure on the "starts humongous" region might de-allocate
2710 // and clear all its "continues humongous" regions and, as a
2711 // result, we might end up processing them twice. So, we'll do
2712 // them first (notice: most closures will ignore them anyway) and
2713 // then we'll do the "starts humongous" region.
2714 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2715 HeapRegion* chr = region_at(ch_index);
2716
2717 // if the region has already been claimed or it's not
2718 // "continues humongous" we're done
2719 if (chr->claim_value() == claim_value ||
2720 !chr->continuesHumongous()) {
2721 break;
2722 }
2723
2724 // No one should have claimed it directly. We can given
2725 // that we claimed its "starts humongous" region.
2726 assert(chr->claim_value() != claim_value, "sanity");
2727 assert(chr->humongous_start_region() == r, "sanity");
2728
2729 if (chr->claimHeapRegion(claim_value)) {
2730 // we should always be able to claim it; no one else should
2731 // be trying to claim this region
2732
2733 bool res2 = cl->doHeapRegion(chr);
2734 assert(!res2, "Should not abort");
2735
2736 // Right now, this holds (i.e., no closure that actually
2737 // does something with "continues humongous" regions
2738 // clears them). We might have to weaken it in the future,
2739 // but let's leave these two asserts here for extra safety.
2740 assert(chr->continuesHumongous(), "should still be the case");
2741 assert(chr->humongous_start_region() == r, "sanity");
2742 } else {
2743 guarantee(false, "we should not reach here");
2744 }
2745 }
2746 }
2747
2748 assert(!r->continuesHumongous(), "sanity");
2749 bool res = cl->doHeapRegion(r);
2750 assert(!res, "Should not abort");
2751 }
2752 }
2753 }
2754
2755 class ResetClaimValuesClosure: public HeapRegionClosure {
2756 public:
2757 bool doHeapRegion(HeapRegion* r) {
2758 r->set_claim_value(HeapRegion::InitialClaimValue);
2759 return false;
2760 }
2761 };
2762
2763 void G1CollectedHeap::reset_heap_region_claim_values() {
2764 ResetClaimValuesClosure blk;
2765 heap_region_iterate(&blk);
2766 }
2767
2768 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2769 ResetClaimValuesClosure blk;
2770 collection_set_iterate(&blk);
2771 }
2772
2773 #ifdef ASSERT
2774 // This checks whether all regions in the heap have the correct claim
2775 // value. I also piggy-backed on this a check to ensure that the
2776 // humongous_start_region() information on "continues humongous"
2777 // regions is correct.
2778
2779 class CheckClaimValuesClosure : public HeapRegionClosure {
2780 private:
2781 jint _claim_value;
2782 uint _failures;
2783 HeapRegion* _sh_region;
2784
2785 public:
2786 CheckClaimValuesClosure(jint claim_value) :
2787 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2788 bool doHeapRegion(HeapRegion* r) {
2789 if (r->claim_value() != _claim_value) {
2790 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2791 "claim value = %d, should be %d",
2792 HR_FORMAT_PARAMS(r),
2793 r->claim_value(), _claim_value);
2794 ++_failures;
2795 }
2796 if (!r->isHumongous()) {
2797 _sh_region = NULL;
2798 } else if (r->startsHumongous()) {
2799 _sh_region = r;
2800 } else if (r->continuesHumongous()) {
2801 if (r->humongous_start_region() != _sh_region) {
2802 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2803 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2804 HR_FORMAT_PARAMS(r),
2805 r->humongous_start_region(),
2806 _sh_region);
2807 ++_failures;
2808 }
2809 }
2810 return false;
2811 }
2812 uint failures() { return _failures; }
2813 };
2814
2815 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2816 CheckClaimValuesClosure cl(claim_value);
2817 heap_region_iterate(&cl);
2818 return cl.failures() == 0;
2819 }
2820
2821 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2822 private:
2823 jint _claim_value;
2824 uint _failures;
2825
2826 public:
2827 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2828 _claim_value(claim_value), _failures(0) { }
2829
2830 uint failures() { return _failures; }
2831
2832 bool doHeapRegion(HeapRegion* hr) {
2833 assert(hr->in_collection_set(), "how?");
2834 assert(!hr->isHumongous(), "H-region in CSet");
2835 if (hr->claim_value() != _claim_value) {
2836 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2837 "claim value = %d, should be %d",
2838 HR_FORMAT_PARAMS(hr),
2839 hr->claim_value(), _claim_value);
2840 _failures += 1;
2841 }
2842 return false;
2843 }
2844 };
2845
2846 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2847 CheckClaimValuesInCSetHRClosure cl(claim_value);
2848 collection_set_iterate(&cl);
2849 return cl.failures() == 0;
2850 }
2851 #endif // ASSERT
2852
2853 // Clear the cached CSet starting regions and (more importantly)
2854 // the time stamps. Called when we reset the GC time stamp.
2855 void G1CollectedHeap::clear_cset_start_regions() {
2856 assert(_worker_cset_start_region != NULL, "sanity");
2857 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2858
2859 int n_queues = MAX2((int)ParallelGCThreads, 1);
2860 for (int i = 0; i < n_queues; i++) {
2861 _worker_cset_start_region[i] = NULL;
2862 _worker_cset_start_region_time_stamp[i] = 0;
2863 }
2864 }
2865
2866 // Given the id of a worker, obtain or calculate a suitable
2867 // starting region for iterating over the current collection set.
2868 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2869 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2870
2871 HeapRegion* result = NULL;
2872 unsigned gc_time_stamp = get_gc_time_stamp();
2873
2874 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2875 // Cached starting region for current worker was set
2876 // during the current pause - so it's valid.
2877 // Note: the cached starting heap region may be NULL
2878 // (when the collection set is empty).
2879 result = _worker_cset_start_region[worker_i];
2880 assert(result == NULL || result->in_collection_set(), "sanity");
2881 return result;
2882 }
2883
2884 // The cached entry was not valid so let's calculate
2885 // a suitable starting heap region for this worker.
2886
2887 // We want the parallel threads to start their collection
2888 // set iteration at different collection set regions to
2889 // avoid contention.
2890 // If we have:
2891 // n collection set regions
2892 // p threads
2893 // Then thread t will start at region floor ((t * n) / p)
2894
2895 result = g1_policy()->collection_set();
2896 if (G1CollectedHeap::use_parallel_gc_threads()) {
2897 uint cs_size = g1_policy()->cset_region_length();
2898 uint active_workers = workers()->active_workers();
2899 assert(UseDynamicNumberOfGCThreads ||
2900 active_workers == workers()->total_workers(),
2901 "Unless dynamic should use total workers");
2902
2903 uint end_ind = (cs_size * worker_i) / active_workers;
2904 uint start_ind = 0;
2905
2906 if (worker_i > 0 &&
2907 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2908 // Previous workers starting region is valid
2909 // so let's iterate from there
2910 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2911 result = _worker_cset_start_region[worker_i - 1];
2912 }
2913
2914 for (uint i = start_ind; i < end_ind; i++) {
2915 result = result->next_in_collection_set();
2916 }
2917 }
2918
2919 // Note: the calculated starting heap region may be NULL
2920 // (when the collection set is empty).
2921 assert(result == NULL || result->in_collection_set(), "sanity");
2922 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2923 "should be updated only once per pause");
2924 _worker_cset_start_region[worker_i] = result;
2925 OrderAccess::storestore();
2926 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2927 return result;
2928 }
2929
2930 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2931 uint no_of_par_workers) {
2932 uint worker_num =
2933 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2934 assert(UseDynamicNumberOfGCThreads ||
2935 no_of_par_workers == workers()->total_workers(),
2936 "Non dynamic should use fixed number of workers");
2937 const uint start_index = n_regions() * worker_i / worker_num;
2938 return region_at(start_index);
2939 }
2940
2941 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2942 HeapRegion* r = g1_policy()->collection_set();
2943 while (r != NULL) {
2944 HeapRegion* next = r->next_in_collection_set();
2945 if (cl->doHeapRegion(r)) {
2946 cl->incomplete();
2947 return;
2948 }
2949 r = next;
2950 }
2951 }
2952
2953 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2954 HeapRegionClosure *cl) {
2955 if (r == NULL) {
2956 // The CSet is empty so there's nothing to do.
2957 return;
2958 }
2959
2960 assert(r->in_collection_set(),
2961 "Start region must be a member of the collection set.");
2962 HeapRegion* cur = r;
2963 while (cur != NULL) {
2964 HeapRegion* next = cur->next_in_collection_set();
2965 if (cl->doHeapRegion(cur) && false) {
2966 cl->incomplete();
2967 return;
2968 }
2969 cur = next;
2970 }
2971 cur = g1_policy()->collection_set();
2972 while (cur != r) {
2973 HeapRegion* next = cur->next_in_collection_set();
2974 if (cl->doHeapRegion(cur) && false) {
2975 cl->incomplete();
2976 return;
2977 }
2978 cur = next;
2979 }
2980 }
2981
2982 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2983 return n_regions() > 0 ? region_at(0) : NULL;
2984 }
2985
2986
2987 Space* G1CollectedHeap::space_containing(const void* addr) const {
2988 Space* res = heap_region_containing(addr);
2989 return res;
2990 }
2991
2992 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2993 Space* sp = space_containing(addr);
2994 if (sp != NULL) {
2995 return sp->block_start(addr);
2996 }
2997 return NULL;
2998 }
2999
3000 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3001 Space* sp = space_containing(addr);
3002 assert(sp != NULL, "block_size of address outside of heap");
3003 return sp->block_size(addr);
3004 }
3005
3006 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3007 Space* sp = space_containing(addr);
3008 return sp->block_is_obj(addr);
3009 }
3010
3011 bool G1CollectedHeap::supports_tlab_allocation() const {
3012 return true;
3013 }
3014
3015 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3016 return HeapRegion::GrainBytes;
3017 }
3018
3019 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3020 // Return the remaining space in the cur alloc region, but not less than
3021 // the min TLAB size.
3022
3023 // Also, this value can be at most the humongous object threshold,
3024 // since we can't allow tlabs to grow big enough to accommodate
3025 // humongous objects.
3026
3027 HeapRegion* hr = _mutator_alloc_region.get();
3028 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3029 if (hr == NULL) {
3030 return max_tlab_size;
3031 } else {
3032 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3033 }
3034 }
3035
3036 size_t G1CollectedHeap::max_capacity() const {
3037 return _g1_reserved.byte_size();
3038 }
3039
3040 jlong G1CollectedHeap::millis_since_last_gc() {
3041 // assert(false, "NYI");
3042 return 0;
3043 }
3044
3045 void G1CollectedHeap::prepare_for_verify() {
3046 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3047 ensure_parsability(false);
3048 }
3049 g1_rem_set()->prepare_for_verify();
3050 }
3051
3052 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3053 VerifyOption vo) {
3054 switch (vo) {
3055 case VerifyOption_G1UsePrevMarking:
3056 return hr->obj_allocated_since_prev_marking(obj);
3057 case VerifyOption_G1UseNextMarking:
3058 return hr->obj_allocated_since_next_marking(obj);
3059 case VerifyOption_G1UseMarkWord:
3060 return false;
3061 default:
3062 ShouldNotReachHere();
3063 }
3064 return false; // keep some compilers happy
3065 }
3066
3067 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3068 switch (vo) {
3069 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3070 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3071 case VerifyOption_G1UseMarkWord: return NULL;
3072 default: ShouldNotReachHere();
3073 }
3074 return NULL; // keep some compilers happy
3075 }
3076
3077 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3078 switch (vo) {
3079 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3080 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3081 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3082 default: ShouldNotReachHere();
3083 }
3084 return false; // keep some compilers happy
3085 }
3086
3087 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3088 switch (vo) {
3089 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3090 case VerifyOption_G1UseNextMarking: return "NTAMS";
3091 case VerifyOption_G1UseMarkWord: return "NONE";
3092 default: ShouldNotReachHere();
3093 }
3094 return NULL; // keep some compilers happy
3095 }
3096
3097 class VerifyRootsClosure: public OopClosure {
3098 private:
3099 G1CollectedHeap* _g1h;
3100 VerifyOption _vo;
3101 bool _failures;
3102 public:
3103 // _vo == UsePrevMarking -> use "prev" marking information,
3104 // _vo == UseNextMarking -> use "next" marking information,
3105 // _vo == UseMarkWord -> use mark word from object header.
3106 VerifyRootsClosure(VerifyOption vo) :
3107 _g1h(G1CollectedHeap::heap()),
3108 _vo(vo),
3109 _failures(false) { }
3110
3111 bool failures() { return _failures; }
3112
3113 template <class T> void do_oop_nv(T* p) {
3114 T heap_oop = oopDesc::load_heap_oop(p);
3115 if (!oopDesc::is_null(heap_oop)) {
3116 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3117 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3118 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3119 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3120 if (_vo == VerifyOption_G1UseMarkWord) {
3121 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3122 }
3123 obj->print_on(gclog_or_tty);
3124 _failures = true;
3125 }
3126 }
3127 }
3128
3129 void do_oop(oop* p) { do_oop_nv(p); }
3130 void do_oop(narrowOop* p) { do_oop_nv(p); }
3131 };
3132
3133 class G1VerifyCodeRootOopClosure: public OopClosure {
3134 G1CollectedHeap* _g1h;
3135 OopClosure* _root_cl;
3136 nmethod* _nm;
3137 VerifyOption _vo;
3138 bool _failures;
3139
3140 template <class T> void do_oop_work(T* p) {
3141 // First verify that this root is live
3142 _root_cl->do_oop(p);
3143
3144 if (!G1VerifyHeapRegionCodeRoots) {
3145 // We're not verifying the code roots attached to heap region.
3146 return;
3147 }
3148
3149 // Don't check the code roots during marking verification in a full GC
3150 if (_vo == VerifyOption_G1UseMarkWord) {
3151 return;
3152 }
3153
3154 // Now verify that the current nmethod (which contains p) is
3155 // in the code root list of the heap region containing the
3156 // object referenced by p.
3157
3158 T heap_oop = oopDesc::load_heap_oop(p);
3159 if (!oopDesc::is_null(heap_oop)) {
3160 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3161
3162 // Now fetch the region containing the object
3163 HeapRegion* hr = _g1h->heap_region_containing(obj);
3164 HeapRegionRemSet* hrrs = hr->rem_set();
3165 // Verify that the strong code root list for this region
3166 // contains the nmethod
3167 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3168 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3169 "from nmethod "PTR_FORMAT" not in strong "
3170 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3171 p, _nm, hr->bottom(), hr->end());
3172 _failures = true;
3173 }
3174 }
3175 }
3176
3177 public:
3178 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3179 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3180
3181 void do_oop(oop* p) { do_oop_work(p); }
3182 void do_oop(narrowOop* p) { do_oop_work(p); }
3183
3184 void set_nmethod(nmethod* nm) { _nm = nm; }
3185 bool failures() { return _failures; }
3186 };
3187
3188 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3189 G1VerifyCodeRootOopClosure* _oop_cl;
3190
3191 public:
3192 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3193 _oop_cl(oop_cl) {}
3194
3195 void do_code_blob(CodeBlob* cb) {
3196 nmethod* nm = cb->as_nmethod_or_null();
3197 if (nm != NULL) {
3198 _oop_cl->set_nmethod(nm);
3199 nm->oops_do(_oop_cl);
3200 }
3201 }
3202 };
3203
3204 class YoungRefCounterClosure : public OopClosure {
3205 G1CollectedHeap* _g1h;
3206 int _count;
3207 public:
3208 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3209 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3210 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3211
3212 int count() { return _count; }
3213 void reset_count() { _count = 0; };
3214 };
3215
3216 class VerifyKlassClosure: public KlassClosure {
3217 YoungRefCounterClosure _young_ref_counter_closure;
3218 OopClosure *_oop_closure;
3219 public:
3220 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3221 void do_klass(Klass* k) {
3222 k->oops_do(_oop_closure);
3223
3224 _young_ref_counter_closure.reset_count();
3225 k->oops_do(&_young_ref_counter_closure);
3226 if (_young_ref_counter_closure.count() > 0) {
3227 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3228 }
3229 }
3230 };
3231
3232 class VerifyLivenessOopClosure: public OopClosure {
3233 G1CollectedHeap* _g1h;
3234 VerifyOption _vo;
3235 public:
3236 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3237 _g1h(g1h), _vo(vo)
3238 { }
3239 void do_oop(narrowOop *p) { do_oop_work(p); }
3240 void do_oop( oop *p) { do_oop_work(p); }
3241
3242 template <class T> void do_oop_work(T *p) {
3243 oop obj = oopDesc::load_decode_heap_oop(p);
3244 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3245 "Dead object referenced by a not dead object");
3246 }
3247 };
3248
3249 class VerifyObjsInRegionClosure: public ObjectClosure {
3250 private:
3251 G1CollectedHeap* _g1h;
3252 size_t _live_bytes;
3253 HeapRegion *_hr;
3254 VerifyOption _vo;
3255 public:
3256 // _vo == UsePrevMarking -> use "prev" marking information,
3257 // _vo == UseNextMarking -> use "next" marking information,
3258 // _vo == UseMarkWord -> use mark word from object header.
3259 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3260 : _live_bytes(0), _hr(hr), _vo(vo) {
3261 _g1h = G1CollectedHeap::heap();
3262 }
3263 void do_object(oop o) {
3264 VerifyLivenessOopClosure isLive(_g1h, _vo);
3265 assert(o != NULL, "Huh?");
3266 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3267 // If the object is alive according to the mark word,
3268 // then verify that the marking information agrees.
3269 // Note we can't verify the contra-positive of the
3270 // above: if the object is dead (according to the mark
3271 // word), it may not be marked, or may have been marked
3272 // but has since became dead, or may have been allocated
3273 // since the last marking.
3274 if (_vo == VerifyOption_G1UseMarkWord) {
3275 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3276 }
3277
3278 o->oop_iterate_no_header(&isLive);
3279 if (!_hr->obj_allocated_since_prev_marking(o)) {
3280 size_t obj_size = o->size(); // Make sure we don't overflow
3281 _live_bytes += (obj_size * HeapWordSize);
3282 }
3283 }
3284 }
3285 size_t live_bytes() { return _live_bytes; }
3286 };
3287
3288 class PrintObjsInRegionClosure : public ObjectClosure {
3289 HeapRegion *_hr;
3290 G1CollectedHeap *_g1;
3291 public:
3292 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3293 _g1 = G1CollectedHeap::heap();
3294 };
3295
3296 void do_object(oop o) {
3297 if (o != NULL) {
3298 HeapWord *start = (HeapWord *) o;
3299 size_t word_sz = o->size();
3300 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3301 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3302 (void*) o, word_sz,
3303 _g1->isMarkedPrev(o),
3304 _g1->isMarkedNext(o),
3305 _hr->obj_allocated_since_prev_marking(o));
3306 HeapWord *end = start + word_sz;
3307 HeapWord *cur;
3308 int *val;
3309 for (cur = start; cur < end; cur++) {
3310 val = (int *) cur;
3311 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3312 }
3313 }
3314 }
3315 };
3316
3317 class VerifyRegionClosure: public HeapRegionClosure {
3318 private:
3319 bool _par;
3320 VerifyOption _vo;
3321 bool _failures;
3322 public:
3323 // _vo == UsePrevMarking -> use "prev" marking information,
3324 // _vo == UseNextMarking -> use "next" marking information,
3325 // _vo == UseMarkWord -> use mark word from object header.
3326 VerifyRegionClosure(bool par, VerifyOption vo)
3327 : _par(par),
3328 _vo(vo),
3329 _failures(false) {}
3330
3331 bool failures() {
3332 return _failures;
3333 }
3334
3335 bool doHeapRegion(HeapRegion* r) {
3336 if (!r->continuesHumongous()) {
3337 bool failures = false;
3338 r->verify(_vo, &failures);
3339 if (failures) {
3340 _failures = true;
3341 } else {
3342 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3343 r->object_iterate(¬_dead_yet_cl);
3344 if (_vo != VerifyOption_G1UseNextMarking) {
3345 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3346 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3347 "max_live_bytes "SIZE_FORMAT" "
3348 "< calculated "SIZE_FORMAT,
3349 r->bottom(), r->end(),
3350 r->max_live_bytes(),
3351 not_dead_yet_cl.live_bytes());
3352 _failures = true;
3353 }
3354 } else {
3355 // When vo == UseNextMarking we cannot currently do a sanity
3356 // check on the live bytes as the calculation has not been
3357 // finalized yet.
3358 }
3359 }
3360 }
3361 return false; // stop the region iteration if we hit a failure
3362 }
3363 };
3364
3365 // This is the task used for parallel verification of the heap regions
3366
3367 class G1ParVerifyTask: public AbstractGangTask {
3368 private:
3369 G1CollectedHeap* _g1h;
3370 VerifyOption _vo;
3371 bool _failures;
3372
3373 public:
3374 // _vo == UsePrevMarking -> use "prev" marking information,
3375 // _vo == UseNextMarking -> use "next" marking information,
3376 // _vo == UseMarkWord -> use mark word from object header.
3377 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3378 AbstractGangTask("Parallel verify task"),
3379 _g1h(g1h),
3380 _vo(vo),
3381 _failures(false) { }
3382
3383 bool failures() {
3384 return _failures;
3385 }
3386
3387 void work(uint worker_id) {
3388 HandleMark hm;
3389 VerifyRegionClosure blk(true, _vo);
3390 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3391 _g1h->workers()->active_workers(),
3392 HeapRegion::ParVerifyClaimValue);
3393 if (blk.failures()) {
3394 _failures = true;
3395 }
3396 }
3397 };
3398
3399 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3400 if (SafepointSynchronize::is_at_safepoint()) {
3401 assert(Thread::current()->is_VM_thread(),
3402 "Expected to be executed serially by the VM thread at this point");
3403
3404 if (!silent) { gclog_or_tty->print("Roots "); }
3405 VerifyRootsClosure rootsCl(vo);
3406 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3407 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3408 VerifyKlassClosure klassCl(this, &rootsCl);
3409
3410 // We apply the relevant closures to all the oops in the
3411 // system dictionary, the string table and the code cache.
3412 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3413
3414 // Need cleared claim bits for the strong roots processing
3415 ClassLoaderDataGraph::clear_claimed_marks();
3416
3417 process_strong_roots(true, // activate StrongRootsScope
3418 false, // we set "is scavenging" to false,
3419 // so we don't reset the dirty cards.
3420 ScanningOption(so), // roots scanning options
3421 &rootsCl,
3422 &blobsCl,
3423 &klassCl
3424 );
3425
3426 bool failures = rootsCl.failures() || codeRootsCl.failures();
3427
3428 if (vo != VerifyOption_G1UseMarkWord) {
3429 // If we're verifying during a full GC then the region sets
3430 // will have been torn down at the start of the GC. Therefore
3431 // verifying the region sets will fail. So we only verify
3432 // the region sets when not in a full GC.
3433 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3434 verify_region_sets();
3435 }
3436
3437 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3438 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3439 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3440 "sanity check");
3441
3442 G1ParVerifyTask task(this, vo);
3443 assert(UseDynamicNumberOfGCThreads ||
3444 workers()->active_workers() == workers()->total_workers(),
3445 "If not dynamic should be using all the workers");
3446 int n_workers = workers()->active_workers();
3447 set_par_threads(n_workers);
3448 workers()->run_task(&task);
3449 set_par_threads(0);
3450 if (task.failures()) {
3451 failures = true;
3452 }
3453
3454 // Checks that the expected amount of parallel work was done.
3455 // The implication is that n_workers is > 0.
3456 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3457 "sanity check");
3458
3459 reset_heap_region_claim_values();
3460
3461 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3462 "sanity check");
3463 } else {
3464 VerifyRegionClosure blk(false, vo);
3465 heap_region_iterate(&blk);
3466 if (blk.failures()) {
3467 failures = true;
3468 }
3469 }
3470 if (!silent) gclog_or_tty->print("RemSet ");
3471 rem_set()->verify();
3472
3473 if (failures) {
3474 gclog_or_tty->print_cr("Heap:");
3475 // It helps to have the per-region information in the output to
3476 // help us track down what went wrong. This is why we call
3477 // print_extended_on() instead of print_on().
3478 print_extended_on(gclog_or_tty);
3479 gclog_or_tty->print_cr("");
3480 #ifndef PRODUCT
3481 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3482 concurrent_mark()->print_reachable("at-verification-failure",
3483 vo, false /* all */);
3484 }
3485 #endif
3486 gclog_or_tty->flush();
3487 }
3488 guarantee(!failures, "there should not have been any failures");
3489 } else {
3490 if (!silent)
3491 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3492 }
3493 }
3494
3495 void G1CollectedHeap::verify(bool silent) {
3496 verify(silent, VerifyOption_G1UsePrevMarking);
3497 }
3498
3499 double G1CollectedHeap::verify(bool guard, const char* msg) {
3500 double verify_time_ms = 0.0;
3501
3502 if (guard && total_collections() >= VerifyGCStartAt) {
3503 double verify_start = os::elapsedTime();
3504 HandleMark hm; // Discard invalid handles created during verification
3505 prepare_for_verify();
3506 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3507 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3508 }
3509
3510 return verify_time_ms;
3511 }
3512
3513 void G1CollectedHeap::verify_before_gc() {
3514 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3515 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3516 }
3517
3518 void G1CollectedHeap::verify_after_gc() {
3519 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3520 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3521 }
3522
3523 class PrintRegionClosure: public HeapRegionClosure {
3524 outputStream* _st;
3525 public:
3526 PrintRegionClosure(outputStream* st) : _st(st) {}
3527 bool doHeapRegion(HeapRegion* r) {
3528 r->print_on(_st);
3529 return false;
3530 }
3531 };
3532
3533 void G1CollectedHeap::print_on(outputStream* st) const {
3534 st->print(" %-20s", "garbage-first heap");
3535 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3536 capacity()/K, used_unlocked()/K);
3537 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3538 _g1_storage.low_boundary(),
3539 _g1_storage.high(),
3540 _g1_storage.high_boundary());
3541 st->cr();
3542 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3543 uint young_regions = _young_list->length();
3544 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3545 (size_t) young_regions * HeapRegion::GrainBytes / K);
3546 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3547 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3548 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3549 st->cr();
3550 MetaspaceAux::print_on(st);
3551 }
3552
3553 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3554 print_on(st);
3555
3556 // Print the per-region information.
3557 st->cr();
3558 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3559 "HS=humongous(starts), HC=humongous(continues), "
3560 "CS=collection set, F=free, TS=gc time stamp, "
3561 "PTAMS=previous top-at-mark-start, "
3562 "NTAMS=next top-at-mark-start)");
3563 PrintRegionClosure blk(st);
3564 heap_region_iterate(&blk);
3565 }
3566
3567 void G1CollectedHeap::print_on_error(outputStream* st) const {
3568 this->CollectedHeap::print_on_error(st);
3569
3570 if (_cm != NULL) {
3571 st->cr();
3572 _cm->print_on_error(st);
3573 }
3574 }
3575
3576 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3577 if (G1CollectedHeap::use_parallel_gc_threads()) {
3578 workers()->print_worker_threads_on(st);
3579 }
3580 _cmThread->print_on(st);
3581 st->cr();
3582 _cm->print_worker_threads_on(st);
3583 _cg1r->print_worker_threads_on(st);
3584 }
3585
3586 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3587 if (G1CollectedHeap::use_parallel_gc_threads()) {
3588 workers()->threads_do(tc);
3589 }
3590 tc->do_thread(_cmThread);
3591 _cg1r->threads_do(tc);
3592 }
3593
3594 void G1CollectedHeap::print_tracing_info() const {
3595 // We'll overload this to mean "trace GC pause statistics."
3596 if (TraceGen0Time || TraceGen1Time) {
3597 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3598 // to that.
3599 g1_policy()->print_tracing_info();
3600 }
3601 if (G1SummarizeRSetStats) {
3602 g1_rem_set()->print_summary_info();
3603 }
3604 if (G1SummarizeConcMark) {
3605 concurrent_mark()->print_summary_info();
3606 }
3607 g1_policy()->print_yg_surv_rate_info();
3608 SpecializationStats::print();
3609 }
3610
3611 #ifndef PRODUCT
3612 // Helpful for debugging RSet issues.
3613
3614 class PrintRSetsClosure : public HeapRegionClosure {
3615 private:
3616 const char* _msg;
3617 size_t _occupied_sum;
3618
3619 public:
3620 bool doHeapRegion(HeapRegion* r) {
3621 HeapRegionRemSet* hrrs = r->rem_set();
3622 size_t occupied = hrrs->occupied();
3623 _occupied_sum += occupied;
3624
3625 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3626 HR_FORMAT_PARAMS(r));
3627 if (occupied == 0) {
3628 gclog_or_tty->print_cr(" RSet is empty");
3629 } else {
3630 hrrs->print();
3631 }
3632 gclog_or_tty->print_cr("----------");
3633 return false;
3634 }
3635
3636 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3637 gclog_or_tty->cr();
3638 gclog_or_tty->print_cr("========================================");
3639 gclog_or_tty->print_cr(msg);
3640 gclog_or_tty->cr();
3641 }
3642
3643 ~PrintRSetsClosure() {
3644 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3645 gclog_or_tty->print_cr("========================================");
3646 gclog_or_tty->cr();
3647 }
3648 };
3649
3650 void G1CollectedHeap::print_cset_rsets() {
3651 PrintRSetsClosure cl("Printing CSet RSets");
3652 collection_set_iterate(&cl);
3653 }
3654
3655 void G1CollectedHeap::print_all_rsets() {
3656 PrintRSetsClosure cl("Printing All RSets");;
3657 heap_region_iterate(&cl);
3658 }
3659 #endif // PRODUCT
3660
3661 G1CollectedHeap* G1CollectedHeap::heap() {
3662 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3663 "not a garbage-first heap");
3664 return _g1h;
3665 }
3666
3667 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3668 // always_do_update_barrier = false;
3669 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3670 // Fill TLAB's and such
3671 ensure_parsability(true);
3672
3673 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3674 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3675 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3676 }
3677 }
3678
3679 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3680
3681 if (G1SummarizeRSetStats &&
3682 (G1SummarizeRSetStatsPeriod > 0) &&
3683 // we are at the end of the GC. Total collections has already been increased.
3684 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3685 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3686 }
3687
3688 // FIXME: what is this about?
3689 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3690 // is set.
3691 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3692 "derived pointer present"));
3693 // always_do_update_barrier = true;
3694
3695 // We have just completed a GC. Update the soft reference
3696 // policy with the new heap occupancy
3697 Universe::update_heap_info_at_gc();
3698 }
3699
3700 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3701 unsigned int gc_count_before,
3702 bool* succeeded,
3703 GCCause::Cause gc_cause) {
3704 assert_heap_not_locked_and_not_at_safepoint();
3705 g1_policy()->record_stop_world_start();
3706 VM_G1IncCollectionPause op(gc_count_before,
3707 word_size,
3708 false, /* should_initiate_conc_mark */
3709 g1_policy()->max_pause_time_ms(),
3710 gc_cause);
3711 VMThread::execute(&op);
3712
3713 HeapWord* result = op.result();
3714 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3715 assert(result == NULL || ret_succeeded,
3716 "the result should be NULL if the VM did not succeed");
3717 *succeeded = ret_succeeded;
3718
3719 assert_heap_not_locked();
3720 return result;
3721 }
3722
3723 void
3724 G1CollectedHeap::doConcurrentMark() {
3725 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3726 if (!_cmThread->in_progress()) {
3727 _cmThread->set_started();
3728 CGC_lock->notify();
3729 }
3730 }
3731
3732 size_t G1CollectedHeap::pending_card_num() {
3733 size_t extra_cards = 0;
3734 JavaThread *curr = Threads::first();
3735 while (curr != NULL) {
3736 DirtyCardQueue& dcq = curr->dirty_card_queue();
3737 extra_cards += dcq.size();
3738 curr = curr->next();
3739 }
3740 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3741 size_t buffer_size = dcqs.buffer_size();
3742 size_t buffer_num = dcqs.completed_buffers_num();
3743
3744 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3745 // in bytes - not the number of 'entries'. We need to convert
3746 // into a number of cards.
3747 return (buffer_size * buffer_num + extra_cards) / oopSize;
3748 }
3749
3750 size_t G1CollectedHeap::cards_scanned() {
3751 return g1_rem_set()->cardsScanned();
3752 }
3753
3754 void
3755 G1CollectedHeap::setup_surviving_young_words() {
3756 assert(_surviving_young_words == NULL, "pre-condition");
3757 uint array_length = g1_policy()->young_cset_region_length();
3758 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3759 if (_surviving_young_words == NULL) {
3760 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3761 "Not enough space for young surv words summary.");
3762 }
3763 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3764 #ifdef ASSERT
3765 for (uint i = 0; i < array_length; ++i) {
3766 assert( _surviving_young_words[i] == 0, "memset above" );
3767 }
3768 #endif // !ASSERT
3769 }
3770
3771 void
3772 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3773 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3774 uint array_length = g1_policy()->young_cset_region_length();
3775 for (uint i = 0; i < array_length; ++i) {
3776 _surviving_young_words[i] += surv_young_words[i];
3777 }
3778 }
3779
3780 void
3781 G1CollectedHeap::cleanup_surviving_young_words() {
3782 guarantee( _surviving_young_words != NULL, "pre-condition" );
3783 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3784 _surviving_young_words = NULL;
3785 }
3786
3787 #ifdef ASSERT
3788 class VerifyCSetClosure: public HeapRegionClosure {
3789 public:
3790 bool doHeapRegion(HeapRegion* hr) {
3791 // Here we check that the CSet region's RSet is ready for parallel
3792 // iteration. The fields that we'll verify are only manipulated
3793 // when the region is part of a CSet and is collected. Afterwards,
3794 // we reset these fields when we clear the region's RSet (when the
3795 // region is freed) so they are ready when the region is
3796 // re-allocated. The only exception to this is if there's an
3797 // evacuation failure and instead of freeing the region we leave
3798 // it in the heap. In that case, we reset these fields during
3799 // evacuation failure handling.
3800 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3801
3802 // Here's a good place to add any other checks we'd like to
3803 // perform on CSet regions.
3804 return false;
3805 }
3806 };
3807 #endif // ASSERT
3808
3809 #if TASKQUEUE_STATS
3810 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3811 st->print_raw_cr("GC Task Stats");
3812 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3813 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3814 }
3815
3816 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3817 print_taskqueue_stats_hdr(st);
3818
3819 TaskQueueStats totals;
3820 const int n = workers() != NULL ? workers()->total_workers() : 1;
3821 for (int i = 0; i < n; ++i) {
3822 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3823 totals += task_queue(i)->stats;
3824 }
3825 st->print_raw("tot "); totals.print(st); st->cr();
3826
3827 DEBUG_ONLY(totals.verify());
3828 }
3829
3830 void G1CollectedHeap::reset_taskqueue_stats() {
3831 const int n = workers() != NULL ? workers()->total_workers() : 1;
3832 for (int i = 0; i < n; ++i) {
3833 task_queue(i)->stats.reset();
3834 }
3835 }
3836 #endif // TASKQUEUE_STATS
3837
3838 void G1CollectedHeap::log_gc_header() {
3839 if (!G1Log::fine()) {
3840 return;
3841 }
3842
3843 gclog_or_tty->date_stamp(PrintGCDateStamps);
3844 gclog_or_tty->stamp(PrintGCTimeStamps);
3845
3846 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3847 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3848 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3849
3850 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3851 }
3852
3853 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3854 if (!G1Log::fine()) {
3855 return;
3856 }
3857
3858 if (G1Log::finer()) {
3859 if (evacuation_failed()) {
3860 gclog_or_tty->print(" (to-space exhausted)");
3861 }
3862 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3863 g1_policy()->phase_times()->note_gc_end();
3864 g1_policy()->phase_times()->print(pause_time_sec);
3865 g1_policy()->print_detailed_heap_transition();
3866 } else {
3867 if (evacuation_failed()) {
3868 gclog_or_tty->print("--");
3869 }
3870 g1_policy()->print_heap_transition();
3871 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3872 }
3873 gclog_or_tty->flush();
3874 }
3875
3876 bool
3877 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3878 assert_at_safepoint(true /* should_be_vm_thread */);
3879 guarantee(!is_gc_active(), "collection is not reentrant");
3880
3881 if (GC_locker::check_active_before_gc()) {
3882 return false;
3883 }
3884
3885 _gc_timer_stw->register_gc_start();
3886
3887 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3888
3889 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3890 ResourceMark rm;
3891
3892 print_heap_before_gc();
3893 trace_heap_before_gc(_gc_tracer_stw);
3894
3895 HRSPhaseSetter x(HRSPhaseEvacuation);
3896 verify_region_sets_optional();
3897 verify_dirty_young_regions();
3898
3899 // This call will decide whether this pause is an initial-mark
3900 // pause. If it is, during_initial_mark_pause() will return true
3901 // for the duration of this pause.
3902 g1_policy()->decide_on_conc_mark_initiation();
3903
3904 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3905 assert(!g1_policy()->during_initial_mark_pause() ||
3906 g1_policy()->gcs_are_young(), "sanity");
3907
3908 // We also do not allow mixed GCs during marking.
3909 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3910
3911 // Record whether this pause is an initial mark. When the current
3912 // thread has completed its logging output and it's safe to signal
3913 // the CM thread, the flag's value in the policy has been reset.
3914 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3915
3916 // Inner scope for scope based logging, timers, and stats collection
3917 {
3918 EvacuationInfo evacuation_info;
3919
3920 if (g1_policy()->during_initial_mark_pause()) {
3921 // We are about to start a marking cycle, so we increment the
3922 // full collection counter.
3923 increment_old_marking_cycles_started();
3924 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3925 }
3926
3927 _gc_tracer_stw->report_yc_type(yc_type());
3928
3929 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3930
3931 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3932 workers()->active_workers() : 1);
3933 double pause_start_sec = os::elapsedTime();
3934 g1_policy()->phase_times()->note_gc_start(active_workers);
3935 log_gc_header();
3936
3937 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3938 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3939
3940 // If the secondary_free_list is not empty, append it to the
3941 // free_list. No need to wait for the cleanup operation to finish;
3942 // the region allocation code will check the secondary_free_list
3943 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3944 // set, skip this step so that the region allocation code has to
3945 // get entries from the secondary_free_list.
3946 if (!G1StressConcRegionFreeing) {
3947 append_secondary_free_list_if_not_empty_with_lock();
3948 }
3949
3950 assert(check_young_list_well_formed(), "young list should be well formed");
3951 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3952 "sanity check");
3953
3954 // Don't dynamically change the number of GC threads this early. A value of
3955 // 0 is used to indicate serial work. When parallel work is done,
3956 // it will be set.
3957
3958 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3959 IsGCActiveMark x;
3960
3961 gc_prologue(false);
3962 increment_total_collections(false /* full gc */);
3963 increment_gc_time_stamp();
3964
3965 verify_before_gc();
3966
3967 COMPILER2_PRESENT(DerivedPointerTable::clear());
3968
3969 // Please see comment in g1CollectedHeap.hpp and
3970 // G1CollectedHeap::ref_processing_init() to see how
3971 // reference processing currently works in G1.
3972
3973 // Enable discovery in the STW reference processor
3974 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3975 true /*verify_no_refs*/);
3976
3977 {
3978 // We want to temporarily turn off discovery by the
3979 // CM ref processor, if necessary, and turn it back on
3980 // on again later if we do. Using a scoped
3981 // NoRefDiscovery object will do this.
3982 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3983
3984 // Forget the current alloc region (we might even choose it to be part
3985 // of the collection set!).
3986 release_mutator_alloc_region();
3987
3988 // We should call this after we retire the mutator alloc
3989 // region(s) so that all the ALLOC / RETIRE events are generated
3990 // before the start GC event.
3991 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3992
3993 // This timing is only used by the ergonomics to handle our pause target.
3994 // It is unclear why this should not include the full pause. We will
3995 // investigate this in CR 7178365.
3996 //
3997 // Preserving the old comment here if that helps the investigation:
3998 //
3999 // The elapsed time induced by the start time below deliberately elides
4000 // the possible verification above.
4001 double sample_start_time_sec = os::elapsedTime();
4002
4003 #if YOUNG_LIST_VERBOSE
4004 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4005 _young_list->print();
4006 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4007 #endif // YOUNG_LIST_VERBOSE
4008
4009 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4010
4011 double scan_wait_start = os::elapsedTime();
4012 // We have to wait until the CM threads finish scanning the
4013 // root regions as it's the only way to ensure that all the
4014 // objects on them have been correctly scanned before we start
4015 // moving them during the GC.
4016 bool waited = _cm->root_regions()->wait_until_scan_finished();
4017 double wait_time_ms = 0.0;
4018 if (waited) {
4019 double scan_wait_end = os::elapsedTime();
4020 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4021 }
4022 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4023
4024 #if YOUNG_LIST_VERBOSE
4025 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4026 _young_list->print();
4027 #endif // YOUNG_LIST_VERBOSE
4028
4029 if (g1_policy()->during_initial_mark_pause()) {
4030 concurrent_mark()->checkpointRootsInitialPre();
4031 }
4032
4033 #if YOUNG_LIST_VERBOSE
4034 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4035 _young_list->print();
4036 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4037 #endif // YOUNG_LIST_VERBOSE
4038
4039 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4040
4041 _cm->note_start_of_gc();
4042 // We should not verify the per-thread SATB buffers given that
4043 // we have not filtered them yet (we'll do so during the
4044 // GC). We also call this after finalize_cset() to
4045 // ensure that the CSet has been finalized.
4046 _cm->verify_no_cset_oops(true /* verify_stacks */,
4047 true /* verify_enqueued_buffers */,
4048 false /* verify_thread_buffers */,
4049 true /* verify_fingers */);
4050
4051 if (_hr_printer.is_active()) {
4052 HeapRegion* hr = g1_policy()->collection_set();
4053 while (hr != NULL) {
4054 G1HRPrinter::RegionType type;
4055 if (!hr->is_young()) {
4056 type = G1HRPrinter::Old;
4057 } else if (hr->is_survivor()) {
4058 type = G1HRPrinter::Survivor;
4059 } else {
4060 type = G1HRPrinter::Eden;
4061 }
4062 _hr_printer.cset(hr);
4063 hr = hr->next_in_collection_set();
4064 }
4065 }
4066
4067 #ifdef ASSERT
4068 VerifyCSetClosure cl;
4069 collection_set_iterate(&cl);
4070 #endif // ASSERT
4071
4072 setup_surviving_young_words();
4073
4074 // Initialize the GC alloc regions.
4075 init_gc_alloc_regions(evacuation_info);
4076
4077 // Actually do the work...
4078 evacuate_collection_set(evacuation_info);
4079
4080 // We do this to mainly verify the per-thread SATB buffers
4081 // (which have been filtered by now) since we didn't verify
4082 // them earlier. No point in re-checking the stacks / enqueued
4083 // buffers given that the CSet has not changed since last time
4084 // we checked.
4085 _cm->verify_no_cset_oops(false /* verify_stacks */,
4086 false /* verify_enqueued_buffers */,
4087 true /* verify_thread_buffers */,
4088 true /* verify_fingers */);
4089
4090 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4091 g1_policy()->clear_collection_set();
4092
4093 cleanup_surviving_young_words();
4094
4095 // Start a new incremental collection set for the next pause.
4096 g1_policy()->start_incremental_cset_building();
4097
4098 // Clear the _cset_fast_test bitmap in anticipation of adding
4099 // regions to the incremental collection set for the next
4100 // evacuation pause.
4101 clear_cset_fast_test();
4102
4103 _young_list->reset_sampled_info();
4104
4105 // Don't check the whole heap at this point as the
4106 // GC alloc regions from this pause have been tagged
4107 // as survivors and moved on to the survivor list.
4108 // Survivor regions will fail the !is_young() check.
4109 assert(check_young_list_empty(false /* check_heap */),
4110 "young list should be empty");
4111
4112 #if YOUNG_LIST_VERBOSE
4113 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4114 _young_list->print();
4115 #endif // YOUNG_LIST_VERBOSE
4116
4117 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4118 _young_list->first_survivor_region(),
4119 _young_list->last_survivor_region());
4120
4121 _young_list->reset_auxilary_lists();
4122
4123 if (evacuation_failed()) {
4124 _summary_bytes_used = recalculate_used();
4125 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4126 for (uint i = 0; i < n_queues; i++) {
4127 if (_evacuation_failed_info_array[i].has_failed()) {
4128 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4129 }
4130 }
4131 } else {
4132 // The "used" of the the collection set have already been subtracted
4133 // when they were freed. Add in the bytes evacuated.
4134 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4135 }
4136
4137 if (g1_policy()->during_initial_mark_pause()) {
4138 // We have to do this before we notify the CM threads that
4139 // they can start working to make sure that all the
4140 // appropriate initialization is done on the CM object.
4141 concurrent_mark()->checkpointRootsInitialPost();
4142 set_marking_started();
4143 // Note that we don't actually trigger the CM thread at
4144 // this point. We do that later when we're sure that
4145 // the current thread has completed its logging output.
4146 }
4147
4148 allocate_dummy_regions();
4149
4150 #if YOUNG_LIST_VERBOSE
4151 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4152 _young_list->print();
4153 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4154 #endif // YOUNG_LIST_VERBOSE
4155
4156 init_mutator_alloc_region();
4157
4158 {
4159 size_t expand_bytes = g1_policy()->expansion_amount();
4160 if (expand_bytes > 0) {
4161 size_t bytes_before = capacity();
4162 // No need for an ergo verbose message here,
4163 // expansion_amount() does this when it returns a value > 0.
4164 if (!expand(expand_bytes)) {
4165 // We failed to expand the heap so let's verify that
4166 // committed/uncommitted amount match the backing store
4167 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4168 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4169 }
4170 }
4171 }
4172
4173 // We redo the verification but now wrt to the new CSet which
4174 // has just got initialized after the previous CSet was freed.
4175 _cm->verify_no_cset_oops(true /* verify_stacks */,
4176 true /* verify_enqueued_buffers */,
4177 true /* verify_thread_buffers */,
4178 true /* verify_fingers */);
4179 _cm->note_end_of_gc();
4180
4181 // This timing is only used by the ergonomics to handle our pause target.
4182 // It is unclear why this should not include the full pause. We will
4183 // investigate this in CR 7178365.
4184 double sample_end_time_sec = os::elapsedTime();
4185 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4186 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4187
4188 MemoryService::track_memory_usage();
4189
4190 // In prepare_for_verify() below we'll need to scan the deferred
4191 // update buffers to bring the RSets up-to-date if
4192 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4193 // the update buffers we'll probably need to scan cards on the
4194 // regions we just allocated to (i.e., the GC alloc
4195 // regions). However, during the last GC we called
4196 // set_saved_mark() on all the GC alloc regions, so card
4197 // scanning might skip the [saved_mark_word()...top()] area of
4198 // those regions (i.e., the area we allocated objects into
4199 // during the last GC). But it shouldn't. Given that
4200 // saved_mark_word() is conditional on whether the GC time stamp
4201 // on the region is current or not, by incrementing the GC time
4202 // stamp here we invalidate all the GC time stamps on all the
4203 // regions and saved_mark_word() will simply return top() for
4204 // all the regions. This is a nicer way of ensuring this rather
4205 // than iterating over the regions and fixing them. In fact, the
4206 // GC time stamp increment here also ensures that
4207 // saved_mark_word() will return top() between pauses, i.e.,
4208 // during concurrent refinement. So we don't need the
4209 // is_gc_active() check to decided which top to use when
4210 // scanning cards (see CR 7039627).
4211 increment_gc_time_stamp();
4212
4213 verify_after_gc();
4214
4215 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4216 ref_processor_stw()->verify_no_references_recorded();
4217
4218 // CM reference discovery will be re-enabled if necessary.
4219 }
4220
4221 // We should do this after we potentially expand the heap so
4222 // that all the COMMIT events are generated before the end GC
4223 // event, and after we retire the GC alloc regions so that all
4224 // RETIRE events are generated before the end GC event.
4225 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4226
4227 if (mark_in_progress()) {
4228 concurrent_mark()->update_g1_committed();
4229 }
4230
4231 #ifdef TRACESPINNING
4232 ParallelTaskTerminator::print_termination_counts();
4233 #endif
4234
4235 gc_epilogue(false);
4236 }
4237
4238 // Print the remainder of the GC log output.
4239 log_gc_footer(os::elapsedTime() - pause_start_sec);
4240
4241 // It is not yet to safe to tell the concurrent mark to
4242 // start as we have some optional output below. We don't want the
4243 // output from the concurrent mark thread interfering with this
4244 // logging output either.
4245
4246 _hrs.verify_optional();
4247 verify_region_sets_optional();
4248
4249 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4250 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4251
4252 print_heap_after_gc();
4253 trace_heap_after_gc(_gc_tracer_stw);
4254
4255 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4256 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4257 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4258 // before any GC notifications are raised.
4259 g1mm()->update_sizes();
4260
4261 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4262 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4263 _gc_timer_stw->register_gc_end();
4264 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4265 }
4266 // It should now be safe to tell the concurrent mark thread to start
4267 // without its logging output interfering with the logging output
4268 // that came from the pause.
4269
4270 if (should_start_conc_mark) {
4271 // CAUTION: after the doConcurrentMark() call below,
4272 // the concurrent marking thread(s) could be running
4273 // concurrently with us. Make sure that anything after
4274 // this point does not assume that we are the only GC thread
4275 // running. Note: of course, the actual marking work will
4276 // not start until the safepoint itself is released in
4277 // ConcurrentGCThread::safepoint_desynchronize().
4278 doConcurrentMark();
4279 }
4280
4281 return true;
4282 }
4283
4284 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4285 {
4286 size_t gclab_word_size;
4287 switch (purpose) {
4288 case GCAllocForSurvived:
4289 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4290 break;
4291 case GCAllocForTenured:
4292 gclab_word_size = _old_plab_stats.desired_plab_sz();
4293 break;
4294 default:
4295 assert(false, "unknown GCAllocPurpose");
4296 gclab_word_size = _old_plab_stats.desired_plab_sz();
4297 break;
4298 }
4299
4300 // Prevent humongous PLAB sizes for two reasons:
4301 // * PLABs are allocated using a similar paths as oops, but should
4302 // never be in a humongous region
4303 // * Allowing humongous PLABs needlessly churns the region free lists
4304 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4305 }
4306
4307 void G1CollectedHeap::init_mutator_alloc_region() {
4308 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4309 _mutator_alloc_region.init();
4310 }
4311
4312 void G1CollectedHeap::release_mutator_alloc_region() {
4313 _mutator_alloc_region.release();
4314 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4315 }
4316
4317 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4318 assert_at_safepoint(true /* should_be_vm_thread */);
4319
4320 _survivor_gc_alloc_region.init();
4321 _old_gc_alloc_region.init();
4322 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4323 _retained_old_gc_alloc_region = NULL;
4324
4325 // We will discard the current GC alloc region if:
4326 // a) it's in the collection set (it can happen!),
4327 // b) it's already full (no point in using it),
4328 // c) it's empty (this means that it was emptied during
4329 // a cleanup and it should be on the free list now), or
4330 // d) it's humongous (this means that it was emptied
4331 // during a cleanup and was added to the free list, but
4332 // has been subsequently used to allocate a humongous
4333 // object that may be less than the region size).
4334 if (retained_region != NULL &&
4335 !retained_region->in_collection_set() &&
4336 !(retained_region->top() == retained_region->end()) &&
4337 !retained_region->is_empty() &&
4338 !retained_region->isHumongous()) {
4339 retained_region->set_saved_mark();
4340 // The retained region was added to the old region set when it was
4341 // retired. We have to remove it now, since we don't allow regions
4342 // we allocate to in the region sets. We'll re-add it later, when
4343 // it's retired again.
4344 _old_set.remove(retained_region);
4345 bool during_im = g1_policy()->during_initial_mark_pause();
4346 retained_region->note_start_of_copying(during_im);
4347 _old_gc_alloc_region.set(retained_region);
4348 _hr_printer.reuse(retained_region);
4349 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4350 }
4351 }
4352
4353 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4354 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4355 _old_gc_alloc_region.count());
4356 _survivor_gc_alloc_region.release();
4357 // If we have an old GC alloc region to release, we'll save it in
4358 // _retained_old_gc_alloc_region. If we don't
4359 // _retained_old_gc_alloc_region will become NULL. This is what we
4360 // want either way so no reason to check explicitly for either
4361 // condition.
4362 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4363
4364 if (ResizePLAB) {
4365 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4366 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4367 }
4368 }
4369
4370 void G1CollectedHeap::abandon_gc_alloc_regions() {
4371 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4372 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4373 _retained_old_gc_alloc_region = NULL;
4374 }
4375
4376 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4377 _drain_in_progress = false;
4378 set_evac_failure_closure(cl);
4379 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4380 }
4381
4382 void G1CollectedHeap::finalize_for_evac_failure() {
4383 assert(_evac_failure_scan_stack != NULL &&
4384 _evac_failure_scan_stack->length() == 0,
4385 "Postcondition");
4386 assert(!_drain_in_progress, "Postcondition");
4387 delete _evac_failure_scan_stack;
4388 _evac_failure_scan_stack = NULL;
4389 }
4390
4391 void G1CollectedHeap::remove_self_forwarding_pointers() {
4392 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4393
4394 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4395
4396 if (G1CollectedHeap::use_parallel_gc_threads()) {
4397 set_par_threads();
4398 workers()->run_task(&rsfp_task);
4399 set_par_threads(0);
4400 } else {
4401 rsfp_task.work(0);
4402 }
4403
4404 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4405
4406 // Reset the claim values in the regions in the collection set.
4407 reset_cset_heap_region_claim_values();
4408
4409 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4410
4411 // Now restore saved marks, if any.
4412 assert(_objs_with_preserved_marks.size() ==
4413 _preserved_marks_of_objs.size(), "Both or none.");
4414 while (!_objs_with_preserved_marks.is_empty()) {
4415 oop obj = _objs_with_preserved_marks.pop();
4416 markOop m = _preserved_marks_of_objs.pop();
4417 obj->set_mark(m);
4418 }
4419 _objs_with_preserved_marks.clear(true);
4420 _preserved_marks_of_objs.clear(true);
4421 }
4422
4423 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4424 _evac_failure_scan_stack->push(obj);
4425 }
4426
4427 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4428 assert(_evac_failure_scan_stack != NULL, "precondition");
4429
4430 while (_evac_failure_scan_stack->length() > 0) {
4431 oop obj = _evac_failure_scan_stack->pop();
4432 _evac_failure_closure->set_region(heap_region_containing(obj));
4433 obj->oop_iterate_backwards(_evac_failure_closure);
4434 }
4435 }
4436
4437 oop
4438 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4439 oop old) {
4440 assert(obj_in_cs(old),
4441 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4442 (HeapWord*) old));
4443 markOop m = old->mark();
4444 oop forward_ptr = old->forward_to_atomic(old);
4445 if (forward_ptr == NULL) {
4446 // Forward-to-self succeeded.
4447 assert(_par_scan_state != NULL, "par scan state");
4448 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4449 uint queue_num = _par_scan_state->queue_num();
4450
4451 _evacuation_failed = true;
4452 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4453 if (_evac_failure_closure != cl) {
4454 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4455 assert(!_drain_in_progress,
4456 "Should only be true while someone holds the lock.");
4457 // Set the global evac-failure closure to the current thread's.
4458 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4459 set_evac_failure_closure(cl);
4460 // Now do the common part.
4461 handle_evacuation_failure_common(old, m);
4462 // Reset to NULL.
4463 set_evac_failure_closure(NULL);
4464 } else {
4465 // The lock is already held, and this is recursive.
4466 assert(_drain_in_progress, "This should only be the recursive case.");
4467 handle_evacuation_failure_common(old, m);
4468 }
4469 return old;
4470 } else {
4471 // Forward-to-self failed. Either someone else managed to allocate
4472 // space for this object (old != forward_ptr) or they beat us in
4473 // self-forwarding it (old == forward_ptr).
4474 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4475 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4476 "should not be in the CSet",
4477 (HeapWord*) old, (HeapWord*) forward_ptr));
4478 return forward_ptr;
4479 }
4480 }
4481
4482 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4483 preserve_mark_if_necessary(old, m);
4484
4485 HeapRegion* r = heap_region_containing(old);
4486 if (!r->evacuation_failed()) {
4487 r->set_evacuation_failed(true);
4488 _hr_printer.evac_failure(r);
4489 }
4490
4491 push_on_evac_failure_scan_stack(old);
4492
4493 if (!_drain_in_progress) {
4494 // prevent recursion in copy_to_survivor_space()
4495 _drain_in_progress = true;
4496 drain_evac_failure_scan_stack();
4497 _drain_in_progress = false;
4498 }
4499 }
4500
4501 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4502 assert(evacuation_failed(), "Oversaving!");
4503 // We want to call the "for_promotion_failure" version only in the
4504 // case of a promotion failure.
4505 if (m->must_be_preserved_for_promotion_failure(obj)) {
4506 _objs_with_preserved_marks.push(obj);
4507 _preserved_marks_of_objs.push(m);
4508 }
4509 }
4510
4511 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4512 size_t word_size) {
4513 if (purpose == GCAllocForSurvived) {
4514 HeapWord* result = survivor_attempt_allocation(word_size);
4515 if (result != NULL) {
4516 return result;
4517 } else {
4518 // Let's try to allocate in the old gen in case we can fit the
4519 // object there.
4520 return old_attempt_allocation(word_size);
4521 }
4522 } else {
4523 assert(purpose == GCAllocForTenured, "sanity");
4524 HeapWord* result = old_attempt_allocation(word_size);
4525 if (result != NULL) {
4526 return result;
4527 } else {
4528 // Let's try to allocate in the survivors in case we can fit the
4529 // object there.
4530 return survivor_attempt_allocation(word_size);
4531 }
4532 }
4533
4534 ShouldNotReachHere();
4535 // Trying to keep some compilers happy.
4536 return NULL;
4537 }
4538
4539 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4540 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4541
4542 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4543 : _g1h(g1h),
4544 _refs(g1h->task_queue(queue_num)),
4545 _dcq(&g1h->dirty_card_queue_set()),
4546 _ct_bs(g1h->g1_barrier_set()),
4547 _g1_rem(g1h->g1_rem_set()),
4548 _hash_seed(17), _queue_num(queue_num),
4549 _term_attempts(0),
4550 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4551 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4552 _age_table(false),
4553 _strong_roots_time(0), _term_time(0),
4554 _alloc_buffer_waste(0), _undo_waste(0) {
4555 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4556 // we "sacrifice" entry 0 to keep track of surviving bytes for
4557 // non-young regions (where the age is -1)
4558 // We also add a few elements at the beginning and at the end in
4559 // an attempt to eliminate cache contention
4560 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4561 uint array_length = PADDING_ELEM_NUM +
4562 real_length +
4563 PADDING_ELEM_NUM;
4564 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4565 if (_surviving_young_words_base == NULL)
4566 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4567 "Not enough space for young surv histo.");
4568 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4569 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4570
4571 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4572 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4573
4574 _start = os::elapsedTime();
4575 }
4576
4577 void
4578 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4579 {
4580 st->print_raw_cr("GC Termination Stats");
4581 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4582 " ------waste (KiB)------");
4583 st->print_raw_cr("thr ms ms % ms % attempts"
4584 " total alloc undo");
4585 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4586 " ------- ------- -------");
4587 }
4588
4589 void
4590 G1ParScanThreadState::print_termination_stats(int i,
4591 outputStream* const st) const
4592 {
4593 const double elapsed_ms = elapsed_time() * 1000.0;
4594 const double s_roots_ms = strong_roots_time() * 1000.0;
4595 const double term_ms = term_time() * 1000.0;
4596 st->print_cr("%3d %9.2f %9.2f %6.2f "
4597 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4598 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4599 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4600 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4601 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4602 alloc_buffer_waste() * HeapWordSize / K,
4603 undo_waste() * HeapWordSize / K);
4604 }
4605
4606 #ifdef ASSERT
4607 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4608 assert(ref != NULL, "invariant");
4609 assert(UseCompressedOops, "sanity");
4610 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4611 oop p = oopDesc::load_decode_heap_oop(ref);
4612 assert(_g1h->is_in_g1_reserved(p),
4613 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4614 return true;
4615 }
4616
4617 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4618 assert(ref != NULL, "invariant");
4619 if (has_partial_array_mask(ref)) {
4620 // Must be in the collection set--it's already been copied.
4621 oop p = clear_partial_array_mask(ref);
4622 assert(_g1h->obj_in_cs(p),
4623 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4624 } else {
4625 oop p = oopDesc::load_decode_heap_oop(ref);
4626 assert(_g1h->is_in_g1_reserved(p),
4627 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4628 }
4629 return true;
4630 }
4631
4632 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4633 if (ref.is_narrow()) {
4634 return verify_ref((narrowOop*) ref);
4635 } else {
4636 return verify_ref((oop*) ref);
4637 }
4638 }
4639 #endif // ASSERT
4640
4641 void G1ParScanThreadState::trim_queue() {
4642 assert(_evac_cl != NULL, "not set");
4643 assert(_evac_failure_cl != NULL, "not set");
4644 assert(_partial_scan_cl != NULL, "not set");
4645
4646 StarTask ref;
4647 do {
4648 // Drain the overflow stack first, so other threads can steal.
4649 while (refs()->pop_overflow(ref)) {
4650 deal_with_reference(ref);
4651 }
4652
4653 while (refs()->pop_local(ref)) {
4654 deal_with_reference(ref);
4655 }
4656 } while (!refs()->is_empty());
4657 }
4658
4659 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4660 G1ParScanThreadState* par_scan_state) :
4661 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4662 _par_scan_state(par_scan_state),
4663 _worker_id(par_scan_state->queue_num()),
4664 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4665 _mark_in_progress(_g1->mark_in_progress()) { }
4666
4667 template <G1Barrier barrier, bool do_mark_object>
4668 void G1ParCopyClosure<barrier, do_mark_object>::mark_object(oop obj) {
4669 #ifdef ASSERT
4670 HeapRegion* hr = _g1->heap_region_containing(obj);
4671 assert(hr != NULL, "sanity");
4672 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4673 #endif // ASSERT
4674
4675 // We know that the object is not moving so it's safe to read its size.
4676 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4677 }
4678
4679 template <G1Barrier barrier, bool do_mark_object>
4680 void G1ParCopyClosure<barrier, do_mark_object>
4681 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4682 #ifdef ASSERT
4683 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4684 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4685 assert(from_obj != to_obj, "should not be self-forwarded");
4686
4687 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4688 assert(from_hr != NULL, "sanity");
4689 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4690
4691 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4692 assert(to_hr != NULL, "sanity");
4693 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4694 #endif // ASSERT
4695
4696 // The object might be in the process of being copied by another
4697 // worker so we cannot trust that its to-space image is
4698 // well-formed. So we have to read its size from its from-space
4699 // image which we know should not be changing.
4700 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4701 }
4702
4703 template <G1Barrier barrier, bool do_mark_object>
4704 oop G1ParCopyClosure<barrier, do_mark_object>
4705 ::copy_to_survivor_space(oop old) {
4706 size_t word_sz = old->size();
4707 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4708 // +1 to make the -1 indexes valid...
4709 int young_index = from_region->young_index_in_cset()+1;
4710 assert( (from_region->is_young() && young_index > 0) ||
4711 (!from_region->is_young() && young_index == 0), "invariant" );
4712 G1CollectorPolicy* g1p = _g1->g1_policy();
4713 markOop m = old->mark();
4714 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4715 : m->age();
4716 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4717 word_sz);
4718 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4719 #ifndef PRODUCT
4720 // Should this evacuation fail?
4721 if (_g1->evacuation_should_fail()) {
4722 if (obj_ptr != NULL) {
4723 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4724 obj_ptr = NULL;
4725 }
4726 }
4727 #endif // !PRODUCT
4728
4729 if (obj_ptr == NULL) {
4730 // This will either forward-to-self, or detect that someone else has
4731 // installed a forwarding pointer.
4732 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4733 }
4734
4735 oop obj = oop(obj_ptr);
4736
4737 // We're going to allocate linearly, so might as well prefetch ahead.
4738 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4739
4740 oop forward_ptr = old->forward_to_atomic(obj);
4741 if (forward_ptr == NULL) {
4742 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4743 if (g1p->track_object_age(alloc_purpose)) {
4744 // We could simply do obj->incr_age(). However, this causes a
4745 // performance issue. obj->incr_age() will first check whether
4746 // the object has a displaced mark by checking its mark word;
4747 // getting the mark word from the new location of the object
4748 // stalls. So, given that we already have the mark word and we
4749 // are about to install it anyway, it's better to increase the
4750 // age on the mark word, when the object does not have a
4751 // displaced mark word. We're not expecting many objects to have
4752 // a displaced marked word, so that case is not optimized
4753 // further (it could be...) and we simply call obj->incr_age().
4754
4755 if (m->has_displaced_mark_helper()) {
4756 // in this case, we have to install the mark word first,
4757 // otherwise obj looks to be forwarded (the old mark word,
4758 // which contains the forward pointer, was copied)
4759 obj->set_mark(m);
4760 obj->incr_age();
4761 } else {
4762 m = m->incr_age();
4763 obj->set_mark(m);
4764 }
4765 _par_scan_state->age_table()->add(obj, word_sz);
4766 } else {
4767 obj->set_mark(m);
4768 }
4769
4770 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4771 surv_young_words[young_index] += word_sz;
4772
4773 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4774 // We keep track of the next start index in the length field of
4775 // the to-space object. The actual length can be found in the
4776 // length field of the from-space object.
4777 arrayOop(obj)->set_length(0);
4778 oop* old_p = set_partial_array_mask(old);
4779 _par_scan_state->push_on_queue(old_p);
4780 } else {
4781 // No point in using the slower heap_region_containing() method,
4782 // given that we know obj is in the heap.
4783 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4784 obj->oop_iterate_backwards(&_scanner);
4785 }
4786 } else {
4787 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4788 obj = forward_ptr;
4789 }
4790 return obj;
4791 }
4792
4793 template <class T>
4794 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4795 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4796 _scanned_klass->record_modified_oops();
4797 }
4798 }
4799
4800 template <G1Barrier barrier, bool do_mark_object>
4801 template <class T>
4802 void G1ParCopyClosure<barrier, do_mark_object>
4803 ::do_oop_work(T* p) {
4804 oop obj = oopDesc::load_decode_heap_oop(p);
4805
4806 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4807
4808 // here the null check is implicit in the cset_fast_test() test
4809 if (_g1->in_cset_fast_test(obj)) {
4810 oop forwardee;
4811 if (obj->is_forwarded()) {
4812 forwardee = obj->forwardee();
4813 } else {
4814 forwardee = copy_to_survivor_space(obj);
4815 }
4816 assert(forwardee != NULL, "forwardee should not be NULL");
4817 oopDesc::encode_store_heap_oop(p, forwardee);
4818 if (do_mark_object && forwardee != obj) {
4819 // If the object is self-forwarded we don't need to explicitly
4820 // mark it, the evacuation failure protocol will do so.
4821 mark_forwarded_object(obj, forwardee);
4822 }
4823
4824 if (barrier == G1BarrierKlass) {
4825 do_klass_barrier(p, forwardee);
4826 }
4827 } else {
4828 // The object is not in collection set. If we're a root scanning
4829 // closure during an initial mark pause (i.e. do_mark_object will
4830 // be true) then attempt to mark the object.
4831 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4832 mark_object(obj);
4833 }
4834 }
4835
4836 if (barrier == G1BarrierEvac && obj != NULL) {
4837 _par_scan_state->update_rs(_from, p, _worker_id);
4838 }
4839 }
4840
4841 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4842 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4843
4844 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4845 assert(has_partial_array_mask(p), "invariant");
4846 oop from_obj = clear_partial_array_mask(p);
4847
4848 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4849 assert(from_obj->is_objArray(), "must be obj array");
4850 objArrayOop from_obj_array = objArrayOop(from_obj);
4851 // The from-space object contains the real length.
4852 int length = from_obj_array->length();
4853
4854 assert(from_obj->is_forwarded(), "must be forwarded");
4855 oop to_obj = from_obj->forwardee();
4856 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4857 objArrayOop to_obj_array = objArrayOop(to_obj);
4858 // We keep track of the next start index in the length field of the
4859 // to-space object.
4860 int next_index = to_obj_array->length();
4861 assert(0 <= next_index && next_index < length,
4862 err_msg("invariant, next index: %d, length: %d", next_index, length));
4863
4864 int start = next_index;
4865 int end = length;
4866 int remainder = end - start;
4867 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4868 if (remainder > 2 * ParGCArrayScanChunk) {
4869 end = start + ParGCArrayScanChunk;
4870 to_obj_array->set_length(end);
4871 // Push the remainder before we process the range in case another
4872 // worker has run out of things to do and can steal it.
4873 oop* from_obj_p = set_partial_array_mask(from_obj);
4874 _par_scan_state->push_on_queue(from_obj_p);
4875 } else {
4876 assert(length == end, "sanity");
4877 // We'll process the final range for this object. Restore the length
4878 // so that the heap remains parsable in case of evacuation failure.
4879 to_obj_array->set_length(end);
4880 }
4881 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4882 // Process indexes [start,end). It will also process the header
4883 // along with the first chunk (i.e., the chunk with start == 0).
4884 // Note that at this point the length field of to_obj_array is not
4885 // correct given that we are using it to keep track of the next
4886 // start index. oop_iterate_range() (thankfully!) ignores the length
4887 // field and only relies on the start / end parameters. It does
4888 // however return the size of the object which will be incorrect. So
4889 // we have to ignore it even if we wanted to use it.
4890 to_obj_array->oop_iterate_range(&_scanner, start, end);
4891 }
4892
4893 class G1ParEvacuateFollowersClosure : public VoidClosure {
4894 protected:
4895 G1CollectedHeap* _g1h;
4896 G1ParScanThreadState* _par_scan_state;
4897 RefToScanQueueSet* _queues;
4898 ParallelTaskTerminator* _terminator;
4899
4900 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4901 RefToScanQueueSet* queues() { return _queues; }
4902 ParallelTaskTerminator* terminator() { return _terminator; }
4903
4904 public:
4905 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4906 G1ParScanThreadState* par_scan_state,
4907 RefToScanQueueSet* queues,
4908 ParallelTaskTerminator* terminator)
4909 : _g1h(g1h), _par_scan_state(par_scan_state),
4910 _queues(queues), _terminator(terminator) {}
4911
4912 void do_void();
4913
4914 private:
4915 inline bool offer_termination();
4916 };
4917
4918 bool G1ParEvacuateFollowersClosure::offer_termination() {
4919 G1ParScanThreadState* const pss = par_scan_state();
4920 pss->start_term_time();
4921 const bool res = terminator()->offer_termination();
4922 pss->end_term_time();
4923 return res;
4924 }
4925
4926 void G1ParEvacuateFollowersClosure::do_void() {
4927 StarTask stolen_task;
4928 G1ParScanThreadState* const pss = par_scan_state();
4929 pss->trim_queue();
4930
4931 do {
4932 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4933 assert(pss->verify_task(stolen_task), "sanity");
4934 if (stolen_task.is_narrow()) {
4935 pss->deal_with_reference((narrowOop*) stolen_task);
4936 } else {
4937 pss->deal_with_reference((oop*) stolen_task);
4938 }
4939
4940 // We've just processed a reference and we might have made
4941 // available new entries on the queues. So we have to make sure
4942 // we drain the queues as necessary.
4943 pss->trim_queue();
4944 }
4945 } while (!offer_termination());
4946
4947 pss->retire_alloc_buffers();
4948 }
4949
4950 class G1KlassScanClosure : public KlassClosure {
4951 G1ParCopyHelper* _closure;
4952 bool _process_only_dirty;
4953 int _count;
4954 public:
4955 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4956 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4957 void do_klass(Klass* klass) {
4958 // If the klass has not been dirtied we know that there's
4959 // no references into the young gen and we can skip it.
4960 if (!_process_only_dirty || klass->has_modified_oops()) {
4961 // Clean the klass since we're going to scavenge all the metadata.
4962 klass->clear_modified_oops();
4963
4964 // Tell the closure that this klass is the Klass to scavenge
4965 // and is the one to dirty if oops are left pointing into the young gen.
4966 _closure->set_scanned_klass(klass);
4967
4968 klass->oops_do(_closure);
4969
4970 _closure->set_scanned_klass(NULL);
4971 }
4972 _count++;
4973 }
4974 };
4975
4976 class G1ParTask : public AbstractGangTask {
4977 protected:
4978 G1CollectedHeap* _g1h;
4979 RefToScanQueueSet *_queues;
4980 ParallelTaskTerminator _terminator;
4981 uint _n_workers;
4982
4983 Mutex _stats_lock;
4984 Mutex* stats_lock() { return &_stats_lock; }
4985
4986 size_t getNCards() {
4987 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4988 / G1BlockOffsetSharedArray::N_bytes;
4989 }
4990
4991 public:
4992 G1ParTask(G1CollectedHeap* g1h,
4993 RefToScanQueueSet *task_queues)
4994 : AbstractGangTask("G1 collection"),
4995 _g1h(g1h),
4996 _queues(task_queues),
4997 _terminator(0, _queues),
4998 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4999 {}
5000
5001 RefToScanQueueSet* queues() { return _queues; }
5002
5003 RefToScanQueue *work_queue(int i) {
5004 return queues()->queue(i);
5005 }
5006
5007 ParallelTaskTerminator* terminator() { return &_terminator; }
5008
5009 virtual void set_for_termination(int active_workers) {
5010 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5011 // in the young space (_par_seq_tasks) in the G1 heap
5012 // for SequentialSubTasksDone.
5013 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5014 // both of which need setting by set_n_termination().
5015 _g1h->SharedHeap::set_n_termination(active_workers);
5016 _g1h->set_n_termination(active_workers);
5017 terminator()->reset_for_reuse(active_workers);
5018 _n_workers = active_workers;
5019 }
5020
5021 void work(uint worker_id) {
5022 if (worker_id >= _n_workers) return; // no work needed this round
5023
5024 double start_time_ms = os::elapsedTime() * 1000.0;
5025 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5026
5027 {
5028 ResourceMark rm;
5029 HandleMark hm;
5030
5031 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5032
5033 G1ParScanThreadState pss(_g1h, worker_id);
5034 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5035 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5036 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5037
5038 pss.set_evac_closure(&scan_evac_cl);
5039 pss.set_evac_failure_closure(&evac_failure_cl);
5040 pss.set_partial_scan_closure(&partial_scan_cl);
5041
5042 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5043 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5044
5045 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5046 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5047
5048 bool only_young = _g1h->g1_policy()->gcs_are_young();
5049 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5050 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5051
5052 OopClosure* scan_root_cl = &only_scan_root_cl;
5053 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5054
5055 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5056 // We also need to mark copied objects.
5057 scan_root_cl = &scan_mark_root_cl;
5058 scan_klasses_cl = &scan_mark_klasses_cl_s;
5059 }
5060
5061 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5062
5063 // Don't scan the scavengable methods in the code cache as part
5064 // of strong root scanning. The code roots that point into a
5065 // region in the collection set are scanned when we scan the
5066 // region's RSet.
5067 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5068
5069 pss.start_strong_roots();
5070 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5071 SharedHeap::ScanningOption(so),
5072 scan_root_cl,
5073 &push_heap_rs_cl,
5074 scan_klasses_cl,
5075 worker_id);
5076 pss.end_strong_roots();
5077
5078 {
5079 double start = os::elapsedTime();
5080 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5081 evac.do_void();
5082 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5083 double term_ms = pss.term_time()*1000.0;
5084 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5085 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5086 }
5087 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5088 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5089
5090 if (ParallelGCVerbose) {
5091 MutexLocker x(stats_lock());
5092 pss.print_termination_stats(worker_id);
5093 }
5094
5095 assert(pss.refs()->is_empty(), "should be empty");
5096
5097 // Close the inner scope so that the ResourceMark and HandleMark
5098 // destructors are executed here and are included as part of the
5099 // "GC Worker Time".
5100 }
5101
5102 double end_time_ms = os::elapsedTime() * 1000.0;
5103 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5104 }
5105 };
5106
5107 // *** Common G1 Evacuation Stuff
5108
5109 // This method is run in a GC worker.
5110
5111 void
5112 G1CollectedHeap::
5113 g1_process_strong_roots(bool is_scavenging,
5114 ScanningOption so,
5115 OopClosure* scan_non_heap_roots,
5116 OopsInHeapRegionClosure* scan_rs,
5117 G1KlassScanClosure* scan_klasses,
5118 int worker_i) {
5119
5120 // First scan the strong roots
5121 double ext_roots_start = os::elapsedTime();
5122 double closure_app_time_sec = 0.0;
5123
5124 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5125
5126 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5127 // Walk the code cache/strong code roots w/o buffering, because StarTask
5128 // cannot handle unaligned oop locations.
5129 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5130
5131 process_strong_roots(false, // no scoping; this is parallel code
5132 is_scavenging, so,
5133 &buf_scan_non_heap_roots,
5134 &eager_scan_code_roots,
5135 scan_klasses
5136 );
5137
5138 // Now the CM ref_processor roots.
5139 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5140 // We need to treat the discovered reference lists of the
5141 // concurrent mark ref processor as roots and keep entries
5142 // (which are added by the marking threads) on them live
5143 // until they can be processed at the end of marking.
5144 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5145 }
5146
5147 // Finish up any enqueued closure apps (attributed as object copy time).
5148 buf_scan_non_heap_roots.done();
5149
5150 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5151
5152 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5153
5154 double ext_root_time_ms =
5155 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5156
5157 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5158
5159 // During conc marking we have to filter the per-thread SATB buffers
5160 // to make sure we remove any oops into the CSet (which will show up
5161 // as implicitly live).
5162 double satb_filtering_ms = 0.0;
5163 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5164 if (mark_in_progress()) {
5165 double satb_filter_start = os::elapsedTime();
5166
5167 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5168
5169 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5170 }
5171 }
5172 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5173
5174 // If this is an initial mark pause, and we're not scanning
5175 // the entire code cache, we need to mark the oops in the
5176 // strong code root lists for the regions that are not in
5177 // the collection set.
5178 // Note all threads participate in this set of root tasks.
5179 double mark_strong_code_roots_ms = 0.0;
5180 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5181 double mark_strong_roots_start = os::elapsedTime();
5182 mark_strong_code_roots(worker_i);
5183 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5184 }
5185 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5186
5187 // Now scan the complement of the collection set.
5188 if (scan_rs != NULL) {
5189 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5190 }
5191 _process_strong_tasks->all_tasks_completed();
5192 }
5193
5194 void
5195 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5196 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5197 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5198 }
5199
5200 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5201 private:
5202 BoolObjectClosure* _is_alive;
5203 int _initial_string_table_size;
5204 int _initial_symbol_table_size;
5205
5206 bool _process_strings;
5207 int _strings_processed;
5208 int _strings_removed;
5209
5210 bool _process_symbols;
5211 int _symbols_processed;
5212 int _symbols_removed;
5213 public:
5214 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5215 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5216 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5217 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5218
5219 _initial_string_table_size = StringTable::the_table()->table_size();
5220 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5221 if (process_strings) {
5222 StringTable::clear_parallel_claimed_index();
5223 }
5224 if (process_symbols) {
5225 SymbolTable::clear_parallel_claimed_index();
5226 }
5227 }
5228
5229 ~G1StringSymbolTableUnlinkTask() {
5230 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5231 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5232 StringTable::parallel_claimed_index(), _initial_string_table_size));
5233 guarantee(!_process_strings || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5234 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5235 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5236 }
5237
5238 void work(uint worker_id) {
5239 if (G1CollectedHeap::use_parallel_gc_threads()) {
5240 int strings_processed = 0;
5241 int strings_removed = 0;
5242 int symbols_processed = 0;
5243 int symbols_removed = 0;
5244 if (_process_strings) {
5245 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5246 Atomic::add(strings_processed, &_strings_processed);
5247 Atomic::add(strings_removed, &_strings_removed);
5248 }
5249 if (_process_symbols) {
5250 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5251 Atomic::add(symbols_processed, &_symbols_processed);
5252 Atomic::add(symbols_removed, &_symbols_removed);
5253 }
5254 } else {
5255 if (_process_strings) {
5256 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5257 }
5258 if (_process_symbols) {
5259 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5260 }
5261 }
5262 }
5263
5264 size_t strings_processed() const { return (size_t)_strings_processed; }
5265 size_t strings_removed() const { return (size_t)_strings_removed; }
5266
5267 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5268 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5269 };
5270
5271 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5272 bool process_strings, bool process_symbols) {
5273 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5274 _g1h->workers()->active_workers() : 1);
5275
5276 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5277 if (G1CollectedHeap::use_parallel_gc_threads()) {
5278 set_par_threads(n_workers);
5279 workers()->run_task(&g1_unlink_task);
5280 set_par_threads(0);
5281 } else {
5282 g1_unlink_task.work(0);
5283 }
5284 if (G1TraceStringSymbolTableScrubbing) {
5285 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5286 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5287 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5288 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5289 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5290 }
5291 }
5292
5293 // Weak Reference Processing support
5294
5295 // An always "is_alive" closure that is used to preserve referents.
5296 // If the object is non-null then it's alive. Used in the preservation
5297 // of referent objects that are pointed to by reference objects
5298 // discovered by the CM ref processor.
5299 class G1AlwaysAliveClosure: public BoolObjectClosure {
5300 G1CollectedHeap* _g1;
5301 public:
5302 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5303 bool do_object_b(oop p) {
5304 if (p != NULL) {
5305 return true;
5306 }
5307 return false;
5308 }
5309 };
5310
5311 bool G1STWIsAliveClosure::do_object_b(oop p) {
5312 // An object is reachable if it is outside the collection set,
5313 // or is inside and copied.
5314 return !_g1->obj_in_cs(p) || p->is_forwarded();
5315 }
5316
5317 // Non Copying Keep Alive closure
5318 class G1KeepAliveClosure: public OopClosure {
5319 G1CollectedHeap* _g1;
5320 public:
5321 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5322 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5323 void do_oop( oop* p) {
5324 oop obj = *p;
5325
5326 if (_g1->obj_in_cs(obj)) {
5327 assert( obj->is_forwarded(), "invariant" );
5328 *p = obj->forwardee();
5329 }
5330 }
5331 };
5332
5333 // Copying Keep Alive closure - can be called from both
5334 // serial and parallel code as long as different worker
5335 // threads utilize different G1ParScanThreadState instances
5336 // and different queues.
5337
5338 class G1CopyingKeepAliveClosure: public OopClosure {
5339 G1CollectedHeap* _g1h;
5340 OopClosure* _copy_non_heap_obj_cl;
5341 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5342 G1ParScanThreadState* _par_scan_state;
5343
5344 public:
5345 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5346 OopClosure* non_heap_obj_cl,
5347 OopsInHeapRegionClosure* metadata_obj_cl,
5348 G1ParScanThreadState* pss):
5349 _g1h(g1h),
5350 _copy_non_heap_obj_cl(non_heap_obj_cl),
5351 _copy_metadata_obj_cl(metadata_obj_cl),
5352 _par_scan_state(pss)
5353 {}
5354
5355 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5356 virtual void do_oop( oop* p) { do_oop_work(p); }
5357
5358 template <class T> void do_oop_work(T* p) {
5359 oop obj = oopDesc::load_decode_heap_oop(p);
5360
5361 if (_g1h->obj_in_cs(obj)) {
5362 // If the referent object has been forwarded (either copied
5363 // to a new location or to itself in the event of an
5364 // evacuation failure) then we need to update the reference
5365 // field and, if both reference and referent are in the G1
5366 // heap, update the RSet for the referent.
5367 //
5368 // If the referent has not been forwarded then we have to keep
5369 // it alive by policy. Therefore we have copy the referent.
5370 //
5371 // If the reference field is in the G1 heap then we can push
5372 // on the PSS queue. When the queue is drained (after each
5373 // phase of reference processing) the object and it's followers
5374 // will be copied, the reference field set to point to the
5375 // new location, and the RSet updated. Otherwise we need to
5376 // use the the non-heap or metadata closures directly to copy
5377 // the referent object and update the pointer, while avoiding
5378 // updating the RSet.
5379
5380 if (_g1h->is_in_g1_reserved(p)) {
5381 _par_scan_state->push_on_queue(p);
5382 } else {
5383 assert(!ClassLoaderDataGraph::contains((address)p),
5384 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5385 PTR_FORMAT, p));
5386 _copy_non_heap_obj_cl->do_oop(p);
5387 }
5388 }
5389 }
5390 };
5391
5392 // Serial drain queue closure. Called as the 'complete_gc'
5393 // closure for each discovered list in some of the
5394 // reference processing phases.
5395
5396 class G1STWDrainQueueClosure: public VoidClosure {
5397 protected:
5398 G1CollectedHeap* _g1h;
5399 G1ParScanThreadState* _par_scan_state;
5400
5401 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5402
5403 public:
5404 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5405 _g1h(g1h),
5406 _par_scan_state(pss)
5407 { }
5408
5409 void do_void() {
5410 G1ParScanThreadState* const pss = par_scan_state();
5411 pss->trim_queue();
5412 }
5413 };
5414
5415 // Parallel Reference Processing closures
5416
5417 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5418 // processing during G1 evacuation pauses.
5419
5420 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5421 private:
5422 G1CollectedHeap* _g1h;
5423 RefToScanQueueSet* _queues;
5424 FlexibleWorkGang* _workers;
5425 int _active_workers;
5426
5427 public:
5428 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5429 FlexibleWorkGang* workers,
5430 RefToScanQueueSet *task_queues,
5431 int n_workers) :
5432 _g1h(g1h),
5433 _queues(task_queues),
5434 _workers(workers),
5435 _active_workers(n_workers)
5436 {
5437 assert(n_workers > 0, "shouldn't call this otherwise");
5438 }
5439
5440 // Executes the given task using concurrent marking worker threads.
5441 virtual void execute(ProcessTask& task);
5442 virtual void execute(EnqueueTask& task);
5443 };
5444
5445 // Gang task for possibly parallel reference processing
5446
5447 class G1STWRefProcTaskProxy: public AbstractGangTask {
5448 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5449 ProcessTask& _proc_task;
5450 G1CollectedHeap* _g1h;
5451 RefToScanQueueSet *_task_queues;
5452 ParallelTaskTerminator* _terminator;
5453
5454 public:
5455 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5456 G1CollectedHeap* g1h,
5457 RefToScanQueueSet *task_queues,
5458 ParallelTaskTerminator* terminator) :
5459 AbstractGangTask("Process reference objects in parallel"),
5460 _proc_task(proc_task),
5461 _g1h(g1h),
5462 _task_queues(task_queues),
5463 _terminator(terminator)
5464 {}
5465
5466 virtual void work(uint worker_id) {
5467 // The reference processing task executed by a single worker.
5468 ResourceMark rm;
5469 HandleMark hm;
5470
5471 G1STWIsAliveClosure is_alive(_g1h);
5472
5473 G1ParScanThreadState pss(_g1h, worker_id);
5474
5475 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5476 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5477 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5478
5479 pss.set_evac_closure(&scan_evac_cl);
5480 pss.set_evac_failure_closure(&evac_failure_cl);
5481 pss.set_partial_scan_closure(&partial_scan_cl);
5482
5483 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5484 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5485
5486 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5487 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5488
5489 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5490 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5491
5492 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5493 // We also need to mark copied objects.
5494 copy_non_heap_cl = ©_mark_non_heap_cl;
5495 copy_metadata_cl = ©_mark_metadata_cl;
5496 }
5497
5498 // Keep alive closure.
5499 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5500
5501 // Complete GC closure
5502 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5503
5504 // Call the reference processing task's work routine.
5505 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5506
5507 // Note we cannot assert that the refs array is empty here as not all
5508 // of the processing tasks (specifically phase2 - pp2_work) execute
5509 // the complete_gc closure (which ordinarily would drain the queue) so
5510 // the queue may not be empty.
5511 }
5512 };
5513
5514 // Driver routine for parallel reference processing.
5515 // Creates an instance of the ref processing gang
5516 // task and has the worker threads execute it.
5517 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5518 assert(_workers != NULL, "Need parallel worker threads.");
5519
5520 ParallelTaskTerminator terminator(_active_workers, _queues);
5521 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5522
5523 _g1h->set_par_threads(_active_workers);
5524 _workers->run_task(&proc_task_proxy);
5525 _g1h->set_par_threads(0);
5526 }
5527
5528 // Gang task for parallel reference enqueueing.
5529
5530 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5531 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5532 EnqueueTask& _enq_task;
5533
5534 public:
5535 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5536 AbstractGangTask("Enqueue reference objects in parallel"),
5537 _enq_task(enq_task)
5538 { }
5539
5540 virtual void work(uint worker_id) {
5541 _enq_task.work(worker_id);
5542 }
5543 };
5544
5545 // Driver routine for parallel reference enqueueing.
5546 // Creates an instance of the ref enqueueing gang
5547 // task and has the worker threads execute it.
5548
5549 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5550 assert(_workers != NULL, "Need parallel worker threads.");
5551
5552 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5553
5554 _g1h->set_par_threads(_active_workers);
5555 _workers->run_task(&enq_task_proxy);
5556 _g1h->set_par_threads(0);
5557 }
5558
5559 // End of weak reference support closures
5560
5561 // Abstract task used to preserve (i.e. copy) any referent objects
5562 // that are in the collection set and are pointed to by reference
5563 // objects discovered by the CM ref processor.
5564
5565 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5566 protected:
5567 G1CollectedHeap* _g1h;
5568 RefToScanQueueSet *_queues;
5569 ParallelTaskTerminator _terminator;
5570 uint _n_workers;
5571
5572 public:
5573 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5574 AbstractGangTask("ParPreserveCMReferents"),
5575 _g1h(g1h),
5576 _queues(task_queues),
5577 _terminator(workers, _queues),
5578 _n_workers(workers)
5579 { }
5580
5581 void work(uint worker_id) {
5582 ResourceMark rm;
5583 HandleMark hm;
5584
5585 G1ParScanThreadState pss(_g1h, worker_id);
5586 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5587 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5588 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5589
5590 pss.set_evac_closure(&scan_evac_cl);
5591 pss.set_evac_failure_closure(&evac_failure_cl);
5592 pss.set_partial_scan_closure(&partial_scan_cl);
5593
5594 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5595
5596
5597 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5598 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5599
5600 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5601 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5602
5603 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5604 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5605
5606 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5607 // We also need to mark copied objects.
5608 copy_non_heap_cl = ©_mark_non_heap_cl;
5609 copy_metadata_cl = ©_mark_metadata_cl;
5610 }
5611
5612 // Is alive closure
5613 G1AlwaysAliveClosure always_alive(_g1h);
5614
5615 // Copying keep alive closure. Applied to referent objects that need
5616 // to be copied.
5617 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5618
5619 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5620
5621 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5622 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5623
5624 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5625 // So this must be true - but assert just in case someone decides to
5626 // change the worker ids.
5627 assert(0 <= worker_id && worker_id < limit, "sanity");
5628 assert(!rp->discovery_is_atomic(), "check this code");
5629
5630 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5631 for (uint idx = worker_id; idx < limit; idx += stride) {
5632 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5633
5634 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5635 while (iter.has_next()) {
5636 // Since discovery is not atomic for the CM ref processor, we
5637 // can see some null referent objects.
5638 iter.load_ptrs(DEBUG_ONLY(true));
5639 oop ref = iter.obj();
5640
5641 // This will filter nulls.
5642 if (iter.is_referent_alive()) {
5643 iter.make_referent_alive();
5644 }
5645 iter.move_to_next();
5646 }
5647 }
5648
5649 // Drain the queue - which may cause stealing
5650 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5651 drain_queue.do_void();
5652 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5653 assert(pss.refs()->is_empty(), "should be");
5654 }
5655 };
5656
5657 // Weak Reference processing during an evacuation pause (part 1).
5658 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5659 double ref_proc_start = os::elapsedTime();
5660
5661 ReferenceProcessor* rp = _ref_processor_stw;
5662 assert(rp->discovery_enabled(), "should have been enabled");
5663
5664 // Any reference objects, in the collection set, that were 'discovered'
5665 // by the CM ref processor should have already been copied (either by
5666 // applying the external root copy closure to the discovered lists, or
5667 // by following an RSet entry).
5668 //
5669 // But some of the referents, that are in the collection set, that these
5670 // reference objects point to may not have been copied: the STW ref
5671 // processor would have seen that the reference object had already
5672 // been 'discovered' and would have skipped discovering the reference,
5673 // but would not have treated the reference object as a regular oop.
5674 // As a result the copy closure would not have been applied to the
5675 // referent object.
5676 //
5677 // We need to explicitly copy these referent objects - the references
5678 // will be processed at the end of remarking.
5679 //
5680 // We also need to do this copying before we process the reference
5681 // objects discovered by the STW ref processor in case one of these
5682 // referents points to another object which is also referenced by an
5683 // object discovered by the STW ref processor.
5684
5685 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5686 no_of_gc_workers == workers()->active_workers(),
5687 "Need to reset active GC workers");
5688
5689 set_par_threads(no_of_gc_workers);
5690 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5691 no_of_gc_workers,
5692 _task_queues);
5693
5694 if (G1CollectedHeap::use_parallel_gc_threads()) {
5695 workers()->run_task(&keep_cm_referents);
5696 } else {
5697 keep_cm_referents.work(0);
5698 }
5699
5700 set_par_threads(0);
5701
5702 // Closure to test whether a referent is alive.
5703 G1STWIsAliveClosure is_alive(this);
5704
5705 // Even when parallel reference processing is enabled, the processing
5706 // of JNI refs is serial and performed serially by the current thread
5707 // rather than by a worker. The following PSS will be used for processing
5708 // JNI refs.
5709
5710 // Use only a single queue for this PSS.
5711 G1ParScanThreadState pss(this, 0);
5712
5713 // We do not embed a reference processor in the copying/scanning
5714 // closures while we're actually processing the discovered
5715 // reference objects.
5716 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5717 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5718 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5719
5720 pss.set_evac_closure(&scan_evac_cl);
5721 pss.set_evac_failure_closure(&evac_failure_cl);
5722 pss.set_partial_scan_closure(&partial_scan_cl);
5723
5724 assert(pss.refs()->is_empty(), "pre-condition");
5725
5726 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5727 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5728
5729 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5730 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5731
5732 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5733 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5734
5735 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5736 // We also need to mark copied objects.
5737 copy_non_heap_cl = ©_mark_non_heap_cl;
5738 copy_metadata_cl = ©_mark_metadata_cl;
5739 }
5740
5741 // Keep alive closure.
5742 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5743
5744 // Serial Complete GC closure
5745 G1STWDrainQueueClosure drain_queue(this, &pss);
5746
5747 // Setup the soft refs policy...
5748 rp->setup_policy(false);
5749
5750 ReferenceProcessorStats stats;
5751 if (!rp->processing_is_mt()) {
5752 // Serial reference processing...
5753 stats = rp->process_discovered_references(&is_alive,
5754 &keep_alive,
5755 &drain_queue,
5756 NULL,
5757 _gc_timer_stw);
5758 } else {
5759 // Parallel reference processing
5760 assert(rp->num_q() == no_of_gc_workers, "sanity");
5761 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5762
5763 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5764 stats = rp->process_discovered_references(&is_alive,
5765 &keep_alive,
5766 &drain_queue,
5767 &par_task_executor,
5768 _gc_timer_stw);
5769 }
5770
5771 _gc_tracer_stw->report_gc_reference_stats(stats);
5772 // We have completed copying any necessary live referent objects
5773 // (that were not copied during the actual pause) so we can
5774 // retire any active alloc buffers
5775 pss.retire_alloc_buffers();
5776 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5777
5778 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5779 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5780 }
5781
5782 // Weak Reference processing during an evacuation pause (part 2).
5783 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5784 double ref_enq_start = os::elapsedTime();
5785
5786 ReferenceProcessor* rp = _ref_processor_stw;
5787 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5788
5789 // Now enqueue any remaining on the discovered lists on to
5790 // the pending list.
5791 if (!rp->processing_is_mt()) {
5792 // Serial reference processing...
5793 rp->enqueue_discovered_references();
5794 } else {
5795 // Parallel reference enqueueing
5796
5797 assert(no_of_gc_workers == workers()->active_workers(),
5798 "Need to reset active workers");
5799 assert(rp->num_q() == no_of_gc_workers, "sanity");
5800 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5801
5802 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5803 rp->enqueue_discovered_references(&par_task_executor);
5804 }
5805
5806 rp->verify_no_references_recorded();
5807 assert(!rp->discovery_enabled(), "should have been disabled");
5808
5809 // FIXME
5810 // CM's reference processing also cleans up the string and symbol tables.
5811 // Should we do that here also? We could, but it is a serial operation
5812 // and could significantly increase the pause time.
5813
5814 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5815 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5816 }
5817
5818 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5819 _expand_heap_after_alloc_failure = true;
5820 _evacuation_failed = false;
5821
5822 // Should G1EvacuationFailureALot be in effect for this GC?
5823 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5824
5825 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5826
5827 // Disable the hot card cache.
5828 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5829 hot_card_cache->reset_hot_cache_claimed_index();
5830 hot_card_cache->set_use_cache(false);
5831
5832 uint n_workers;
5833 if (G1CollectedHeap::use_parallel_gc_threads()) {
5834 n_workers =
5835 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5836 workers()->active_workers(),
5837 Threads::number_of_non_daemon_threads());
5838 assert(UseDynamicNumberOfGCThreads ||
5839 n_workers == workers()->total_workers(),
5840 "If not dynamic should be using all the workers");
5841 workers()->set_active_workers(n_workers);
5842 set_par_threads(n_workers);
5843 } else {
5844 assert(n_par_threads() == 0,
5845 "Should be the original non-parallel value");
5846 n_workers = 1;
5847 }
5848
5849 G1ParTask g1_par_task(this, _task_queues);
5850
5851 init_for_evac_failure(NULL);
5852
5853 rem_set()->prepare_for_younger_refs_iterate(true);
5854
5855 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5856 double start_par_time_sec = os::elapsedTime();
5857 double end_par_time_sec;
5858
5859 {
5860 StrongRootsScope srs(this);
5861
5862 if (G1CollectedHeap::use_parallel_gc_threads()) {
5863 // The individual threads will set their evac-failure closures.
5864 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5865 // These tasks use ShareHeap::_process_strong_tasks
5866 assert(UseDynamicNumberOfGCThreads ||
5867 workers()->active_workers() == workers()->total_workers(),
5868 "If not dynamic should be using all the workers");
5869 workers()->run_task(&g1_par_task);
5870 } else {
5871 g1_par_task.set_for_termination(n_workers);
5872 g1_par_task.work(0);
5873 }
5874 end_par_time_sec = os::elapsedTime();
5875
5876 // Closing the inner scope will execute the destructor
5877 // for the StrongRootsScope object. We record the current
5878 // elapsed time before closing the scope so that time
5879 // taken for the SRS destructor is NOT included in the
5880 // reported parallel time.
5881 }
5882
5883 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5884 g1_policy()->phase_times()->record_par_time(par_time_ms);
5885
5886 double code_root_fixup_time_ms =
5887 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5888 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5889
5890 set_par_threads(0);
5891
5892 // Process any discovered reference objects - we have
5893 // to do this _before_ we retire the GC alloc regions
5894 // as we may have to copy some 'reachable' referent
5895 // objects (and their reachable sub-graphs) that were
5896 // not copied during the pause.
5897 process_discovered_references(n_workers);
5898
5899 // Weak root processing.
5900 {
5901 G1STWIsAliveClosure is_alive(this);
5902 G1KeepAliveClosure keep_alive(this);
5903 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5904 }
5905
5906 release_gc_alloc_regions(n_workers, evacuation_info);
5907 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5908
5909 // Reset and re-enable the hot card cache.
5910 // Note the counts for the cards in the regions in the
5911 // collection set are reset when the collection set is freed.
5912 hot_card_cache->reset_hot_cache();
5913 hot_card_cache->set_use_cache(true);
5914
5915 // Migrate the strong code roots attached to each region in
5916 // the collection set. Ideally we would like to do this
5917 // after we have finished the scanning/evacuation of the
5918 // strong code roots for a particular heap region.
5919 migrate_strong_code_roots();
5920
5921 if (g1_policy()->during_initial_mark_pause()) {
5922 // Reset the claim values set during marking the strong code roots
5923 reset_heap_region_claim_values();
5924 }
5925
5926 finalize_for_evac_failure();
5927
5928 if (evacuation_failed()) {
5929 remove_self_forwarding_pointers();
5930
5931 // Reset the G1EvacuationFailureALot counters and flags
5932 // Note: the values are reset only when an actual
5933 // evacuation failure occurs.
5934 NOT_PRODUCT(reset_evacuation_should_fail();)
5935 }
5936
5937 // Enqueue any remaining references remaining on the STW
5938 // reference processor's discovered lists. We need to do
5939 // this after the card table is cleaned (and verified) as
5940 // the act of enqueueing entries on to the pending list
5941 // will log these updates (and dirty their associated
5942 // cards). We need these updates logged to update any
5943 // RSets.
5944 enqueue_discovered_references(n_workers);
5945
5946 if (G1DeferredRSUpdate) {
5947 RedirtyLoggedCardTableEntryFastClosure redirty;
5948 dirty_card_queue_set().set_closure(&redirty);
5949 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5950
5951 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5952 dcq.merge_bufferlists(&dirty_card_queue_set());
5953 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5954 }
5955 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5956 }
5957
5958 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5959 size_t* pre_used,
5960 FreeRegionList* free_list,
5961 OldRegionSet* old_proxy_set,
5962 HumongousRegionSet* humongous_proxy_set,
5963 HRRSCleanupTask* hrrs_cleanup_task,
5964 bool par) {
5965 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5966 if (hr->isHumongous()) {
5967 assert(hr->startsHumongous(), "we should only see starts humongous");
5968 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5969 } else {
5970 _old_set.remove_with_proxy(hr, old_proxy_set);
5971 free_region(hr, pre_used, free_list, par);
5972 }
5973 } else {
5974 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5975 }
5976 }
5977
5978 void G1CollectedHeap::free_region(HeapRegion* hr,
5979 size_t* pre_used,
5980 FreeRegionList* free_list,
5981 bool par) {
5982 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5983 assert(!hr->is_empty(), "the region should not be empty");
5984 assert(free_list != NULL, "pre-condition");
5985
5986 // Clear the card counts for this region.
5987 // Note: we only need to do this if the region is not young
5988 // (since we don't refine cards in young regions).
5989 if (!hr->is_young()) {
5990 _cg1r->hot_card_cache()->reset_card_counts(hr);
5991 }
5992 *pre_used += hr->used();
5993 hr->hr_clear(par, true /* clear_space */);
5994 free_list->add_as_head(hr);
5995 }
5996
5997 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5998 size_t* pre_used,
5999 FreeRegionList* free_list,
6000 HumongousRegionSet* humongous_proxy_set,
6001 bool par) {
6002 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6003 assert(free_list != NULL, "pre-condition");
6004 assert(humongous_proxy_set != NULL, "pre-condition");
6005
6006 size_t hr_used = hr->used();
6007 size_t hr_capacity = hr->capacity();
6008 size_t hr_pre_used = 0;
6009 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
6010 // We need to read this before we make the region non-humongous,
6011 // otherwise the information will be gone.
6012 uint last_index = hr->last_hc_index();
6013 hr->set_notHumongous();
6014 free_region(hr, &hr_pre_used, free_list, par);
6015
6016 uint i = hr->hrs_index() + 1;
6017 while (i < last_index) {
6018 HeapRegion* curr_hr = region_at(i);
6019 assert(curr_hr->continuesHumongous(), "invariant");
6020 curr_hr->set_notHumongous();
6021 free_region(curr_hr, &hr_pre_used, free_list, par);
6022 i += 1;
6023 }
6024 assert(hr_pre_used == hr_used,
6025 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
6026 "should be the same", hr_pre_used, hr_used));
6027 *pre_used += hr_pre_used;
6028 }
6029
6030 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
6031 FreeRegionList* free_list,
6032 OldRegionSet* old_proxy_set,
6033 HumongousRegionSet* humongous_proxy_set,
6034 bool par) {
6035 if (pre_used > 0) {
6036 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
6037 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
6038 assert(_summary_bytes_used >= pre_used,
6039 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
6040 "should be >= pre_used: "SIZE_FORMAT,
6041 _summary_bytes_used, pre_used));
6042 _summary_bytes_used -= pre_used;
6043 }
6044 if (free_list != NULL && !free_list->is_empty()) {
6045 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6046 _free_list.add_as_head(free_list);
6047 }
6048 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
6049 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6050 _old_set.update_from_proxy(old_proxy_set);
6051 }
6052 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
6053 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6054 _humongous_set.update_from_proxy(humongous_proxy_set);
6055 }
6056 }
6057
6058 class G1ParCleanupCTTask : public AbstractGangTask {
6059 G1SATBCardTableModRefBS* _ct_bs;
6060 G1CollectedHeap* _g1h;
6061 HeapRegion* volatile _su_head;
6062 public:
6063 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6064 G1CollectedHeap* g1h) :
6065 AbstractGangTask("G1 Par Cleanup CT Task"),
6066 _ct_bs(ct_bs), _g1h(g1h) { }
6067
6068 void work(uint worker_id) {
6069 HeapRegion* r;
6070 while (r = _g1h->pop_dirty_cards_region()) {
6071 clear_cards(r);
6072 }
6073 }
6074
6075 void clear_cards(HeapRegion* r) {
6076 // Cards of the survivors should have already been dirtied.
6077 if (!r->is_survivor()) {
6078 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6079 }
6080 }
6081 };
6082
6083 #ifndef PRODUCT
6084 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6085 G1CollectedHeap* _g1h;
6086 G1SATBCardTableModRefBS* _ct_bs;
6087 public:
6088 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6089 : _g1h(g1h), _ct_bs(ct_bs) { }
6090 virtual bool doHeapRegion(HeapRegion* r) {
6091 if (r->is_survivor()) {
6092 _g1h->verify_dirty_region(r);
6093 } else {
6094 _g1h->verify_not_dirty_region(r);
6095 }
6096 return false;
6097 }
6098 };
6099
6100 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6101 // All of the region should be clean.
6102 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6103 MemRegion mr(hr->bottom(), hr->end());
6104 ct_bs->verify_not_dirty_region(mr);
6105 }
6106
6107 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6108 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6109 // dirty allocated blocks as they allocate them. The thread that
6110 // retires each region and replaces it with a new one will do a
6111 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6112 // not dirty that area (one less thing to have to do while holding
6113 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6114 // is dirty.
6115 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6116 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6117 if (hr->is_young()) {
6118 ct_bs->verify_g1_young_region(mr);
6119 } else {
6120 ct_bs->verify_dirty_region(mr);
6121 }
6122 }
6123
6124 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6125 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6126 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6127 verify_dirty_region(hr);
6128 }
6129 }
6130
6131 void G1CollectedHeap::verify_dirty_young_regions() {
6132 verify_dirty_young_list(_young_list->first_region());
6133 }
6134 #endif
6135
6136 void G1CollectedHeap::cleanUpCardTable() {
6137 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6138 double start = os::elapsedTime();
6139
6140 {
6141 // Iterate over the dirty cards region list.
6142 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6143
6144 if (G1CollectedHeap::use_parallel_gc_threads()) {
6145 set_par_threads();
6146 workers()->run_task(&cleanup_task);
6147 set_par_threads(0);
6148 } else {
6149 while (_dirty_cards_region_list) {
6150 HeapRegion* r = _dirty_cards_region_list;
6151 cleanup_task.clear_cards(r);
6152 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6153 if (_dirty_cards_region_list == r) {
6154 // The last region.
6155 _dirty_cards_region_list = NULL;
6156 }
6157 r->set_next_dirty_cards_region(NULL);
6158 }
6159 }
6160 #ifndef PRODUCT
6161 if (G1VerifyCTCleanup || VerifyAfterGC) {
6162 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6163 heap_region_iterate(&cleanup_verifier);
6164 }
6165 #endif
6166 }
6167
6168 double elapsed = os::elapsedTime() - start;
6169 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6170 }
6171
6172 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6173 size_t pre_used = 0;
6174 FreeRegionList local_free_list("Local List for CSet Freeing");
6175
6176 double young_time_ms = 0.0;
6177 double non_young_time_ms = 0.0;
6178
6179 // Since the collection set is a superset of the the young list,
6180 // all we need to do to clear the young list is clear its
6181 // head and length, and unlink any young regions in the code below
6182 _young_list->clear();
6183
6184 G1CollectorPolicy* policy = g1_policy();
6185
6186 double start_sec = os::elapsedTime();
6187 bool non_young = true;
6188
6189 HeapRegion* cur = cs_head;
6190 int age_bound = -1;
6191 size_t rs_lengths = 0;
6192
6193 while (cur != NULL) {
6194 assert(!is_on_master_free_list(cur), "sanity");
6195 if (non_young) {
6196 if (cur->is_young()) {
6197 double end_sec = os::elapsedTime();
6198 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6199 non_young_time_ms += elapsed_ms;
6200
6201 start_sec = os::elapsedTime();
6202 non_young = false;
6203 }
6204 } else {
6205 if (!cur->is_young()) {
6206 double end_sec = os::elapsedTime();
6207 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6208 young_time_ms += elapsed_ms;
6209
6210 start_sec = os::elapsedTime();
6211 non_young = true;
6212 }
6213 }
6214
6215 rs_lengths += cur->rem_set()->occupied();
6216
6217 HeapRegion* next = cur->next_in_collection_set();
6218 assert(cur->in_collection_set(), "bad CS");
6219 cur->set_next_in_collection_set(NULL);
6220 cur->set_in_collection_set(false);
6221
6222 if (cur->is_young()) {
6223 int index = cur->young_index_in_cset();
6224 assert(index != -1, "invariant");
6225 assert((uint) index < policy->young_cset_region_length(), "invariant");
6226 size_t words_survived = _surviving_young_words[index];
6227 cur->record_surv_words_in_group(words_survived);
6228
6229 // At this point the we have 'popped' cur from the collection set
6230 // (linked via next_in_collection_set()) but it is still in the
6231 // young list (linked via next_young_region()). Clear the
6232 // _next_young_region field.
6233 cur->set_next_young_region(NULL);
6234 } else {
6235 int index = cur->young_index_in_cset();
6236 assert(index == -1, "invariant");
6237 }
6238
6239 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6240 (!cur->is_young() && cur->young_index_in_cset() == -1),
6241 "invariant" );
6242
6243 if (!cur->evacuation_failed()) {
6244 MemRegion used_mr = cur->used_region();
6245
6246 // And the region is empty.
6247 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6248 free_region(cur, &pre_used, &local_free_list, false /* par */);
6249 } else {
6250 cur->uninstall_surv_rate_group();
6251 if (cur->is_young()) {
6252 cur->set_young_index_in_cset(-1);
6253 }
6254 cur->set_not_young();
6255 cur->set_evacuation_failed(false);
6256 // The region is now considered to be old.
6257 _old_set.add(cur);
6258 evacuation_info.increment_collectionset_used_after(cur->used());
6259 }
6260 cur = next;
6261 }
6262
6263 evacuation_info.set_regions_freed(local_free_list.length());
6264 policy->record_max_rs_lengths(rs_lengths);
6265 policy->cset_regions_freed();
6266
6267 double end_sec = os::elapsedTime();
6268 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6269
6270 if (non_young) {
6271 non_young_time_ms += elapsed_ms;
6272 } else {
6273 young_time_ms += elapsed_ms;
6274 }
6275
6276 update_sets_after_freeing_regions(pre_used, &local_free_list,
6277 NULL /* old_proxy_set */,
6278 NULL /* humongous_proxy_set */,
6279 false /* par */);
6280 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6281 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6282 }
6283
6284 // This routine is similar to the above but does not record
6285 // any policy statistics or update free lists; we are abandoning
6286 // the current incremental collection set in preparation of a
6287 // full collection. After the full GC we will start to build up
6288 // the incremental collection set again.
6289 // This is only called when we're doing a full collection
6290 // and is immediately followed by the tearing down of the young list.
6291
6292 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6293 HeapRegion* cur = cs_head;
6294
6295 while (cur != NULL) {
6296 HeapRegion* next = cur->next_in_collection_set();
6297 assert(cur->in_collection_set(), "bad CS");
6298 cur->set_next_in_collection_set(NULL);
6299 cur->set_in_collection_set(false);
6300 cur->set_young_index_in_cset(-1);
6301 cur = next;
6302 }
6303 }
6304
6305 void G1CollectedHeap::set_free_regions_coming() {
6306 if (G1ConcRegionFreeingVerbose) {
6307 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6308 "setting free regions coming");
6309 }
6310
6311 assert(!free_regions_coming(), "pre-condition");
6312 _free_regions_coming = true;
6313 }
6314
6315 void G1CollectedHeap::reset_free_regions_coming() {
6316 assert(free_regions_coming(), "pre-condition");
6317
6318 {
6319 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6320 _free_regions_coming = false;
6321 SecondaryFreeList_lock->notify_all();
6322 }
6323
6324 if (G1ConcRegionFreeingVerbose) {
6325 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6326 "reset free regions coming");
6327 }
6328 }
6329
6330 void G1CollectedHeap::wait_while_free_regions_coming() {
6331 // Most of the time we won't have to wait, so let's do a quick test
6332 // first before we take the lock.
6333 if (!free_regions_coming()) {
6334 return;
6335 }
6336
6337 if (G1ConcRegionFreeingVerbose) {
6338 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6339 "waiting for free regions");
6340 }
6341
6342 {
6343 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6344 while (free_regions_coming()) {
6345 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6346 }
6347 }
6348
6349 if (G1ConcRegionFreeingVerbose) {
6350 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6351 "done waiting for free regions");
6352 }
6353 }
6354
6355 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6356 assert(heap_lock_held_for_gc(),
6357 "the heap lock should already be held by or for this thread");
6358 _young_list->push_region(hr);
6359 }
6360
6361 class NoYoungRegionsClosure: public HeapRegionClosure {
6362 private:
6363 bool _success;
6364 public:
6365 NoYoungRegionsClosure() : _success(true) { }
6366 bool doHeapRegion(HeapRegion* r) {
6367 if (r->is_young()) {
6368 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6369 r->bottom(), r->end());
6370 _success = false;
6371 }
6372 return false;
6373 }
6374 bool success() { return _success; }
6375 };
6376
6377 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6378 bool ret = _young_list->check_list_empty(check_sample);
6379
6380 if (check_heap) {
6381 NoYoungRegionsClosure closure;
6382 heap_region_iterate(&closure);
6383 ret = ret && closure.success();
6384 }
6385
6386 return ret;
6387 }
6388
6389 class TearDownRegionSetsClosure : public HeapRegionClosure {
6390 private:
6391 OldRegionSet *_old_set;
6392
6393 public:
6394 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6395
6396 bool doHeapRegion(HeapRegion* r) {
6397 if (r->is_empty()) {
6398 // We ignore empty regions, we'll empty the free list afterwards
6399 } else if (r->is_young()) {
6400 // We ignore young regions, we'll empty the young list afterwards
6401 } else if (r->isHumongous()) {
6402 // We ignore humongous regions, we're not tearing down the
6403 // humongous region set
6404 } else {
6405 // The rest should be old
6406 _old_set->remove(r);
6407 }
6408 return false;
6409 }
6410
6411 ~TearDownRegionSetsClosure() {
6412 assert(_old_set->is_empty(), "post-condition");
6413 }
6414 };
6415
6416 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6417 assert_at_safepoint(true /* should_be_vm_thread */);
6418
6419 if (!free_list_only) {
6420 TearDownRegionSetsClosure cl(&_old_set);
6421 heap_region_iterate(&cl);
6422
6423 // Need to do this after the heap iteration to be able to
6424 // recognize the young regions and ignore them during the iteration.
6425 _young_list->empty_list();
6426 }
6427 _free_list.remove_all();
6428 }
6429
6430 class RebuildRegionSetsClosure : public HeapRegionClosure {
6431 private:
6432 bool _free_list_only;
6433 OldRegionSet* _old_set;
6434 FreeRegionList* _free_list;
6435 size_t _total_used;
6436
6437 public:
6438 RebuildRegionSetsClosure(bool free_list_only,
6439 OldRegionSet* old_set, FreeRegionList* free_list) :
6440 _free_list_only(free_list_only),
6441 _old_set(old_set), _free_list(free_list), _total_used(0) {
6442 assert(_free_list->is_empty(), "pre-condition");
6443 if (!free_list_only) {
6444 assert(_old_set->is_empty(), "pre-condition");
6445 }
6446 }
6447
6448 bool doHeapRegion(HeapRegion* r) {
6449 if (r->continuesHumongous()) {
6450 return false;
6451 }
6452
6453 if (r->is_empty()) {
6454 // Add free regions to the free list
6455 _free_list->add_as_tail(r);
6456 } else if (!_free_list_only) {
6457 assert(!r->is_young(), "we should not come across young regions");
6458
6459 if (r->isHumongous()) {
6460 // We ignore humongous regions, we left the humongous set unchanged
6461 } else {
6462 // The rest should be old, add them to the old set
6463 _old_set->add(r);
6464 }
6465 _total_used += r->used();
6466 }
6467
6468 return false;
6469 }
6470
6471 size_t total_used() {
6472 return _total_used;
6473 }
6474 };
6475
6476 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6477 assert_at_safepoint(true /* should_be_vm_thread */);
6478
6479 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6480 heap_region_iterate(&cl);
6481
6482 if (!free_list_only) {
6483 _summary_bytes_used = cl.total_used();
6484 }
6485 assert(_summary_bytes_used == recalculate_used(),
6486 err_msg("inconsistent _summary_bytes_used, "
6487 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6488 _summary_bytes_used, recalculate_used()));
6489 }
6490
6491 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6492 _refine_cte_cl->set_concurrent(concurrent);
6493 }
6494
6495 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6496 HeapRegion* hr = heap_region_containing(p);
6497 if (hr == NULL) {
6498 return false;
6499 } else {
6500 return hr->is_in(p);
6501 }
6502 }
6503
6504 // Methods for the mutator alloc region
6505
6506 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6507 bool force) {
6508 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6509 assert(!force || g1_policy()->can_expand_young_list(),
6510 "if force is true we should be able to expand the young list");
6511 bool young_list_full = g1_policy()->is_young_list_full();
6512 if (force || !young_list_full) {
6513 HeapRegion* new_alloc_region = new_region(word_size,
6514 false /* do_expand */);
6515 if (new_alloc_region != NULL) {
6516 set_region_short_lived_locked(new_alloc_region);
6517 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6518 return new_alloc_region;
6519 }
6520 }
6521 return NULL;
6522 }
6523
6524 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6525 size_t allocated_bytes) {
6526 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6527 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6528
6529 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6530 _summary_bytes_used += allocated_bytes;
6531 _hr_printer.retire(alloc_region);
6532 // We update the eden sizes here, when the region is retired,
6533 // instead of when it's allocated, since this is the point that its
6534 // used space has been recored in _summary_bytes_used.
6535 g1mm()->update_eden_size();
6536 }
6537
6538 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6539 bool force) {
6540 return _g1h->new_mutator_alloc_region(word_size, force);
6541 }
6542
6543 void G1CollectedHeap::set_par_threads() {
6544 // Don't change the number of workers. Use the value previously set
6545 // in the workgroup.
6546 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6547 uint n_workers = workers()->active_workers();
6548 assert(UseDynamicNumberOfGCThreads ||
6549 n_workers == workers()->total_workers(),
6550 "Otherwise should be using the total number of workers");
6551 if (n_workers == 0) {
6552 assert(false, "Should have been set in prior evacuation pause.");
6553 n_workers = ParallelGCThreads;
6554 workers()->set_active_workers(n_workers);
6555 }
6556 set_par_threads(n_workers);
6557 }
6558
6559 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6560 size_t allocated_bytes) {
6561 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6562 }
6563
6564 // Methods for the GC alloc regions
6565
6566 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6567 uint count,
6568 GCAllocPurpose ap) {
6569 assert(FreeList_lock->owned_by_self(), "pre-condition");
6570
6571 if (count < g1_policy()->max_regions(ap)) {
6572 HeapRegion* new_alloc_region = new_region(word_size,
6573 true /* do_expand */);
6574 if (new_alloc_region != NULL) {
6575 // We really only need to do this for old regions given that we
6576 // should never scan survivors. But it doesn't hurt to do it
6577 // for survivors too.
6578 new_alloc_region->set_saved_mark();
6579 if (ap == GCAllocForSurvived) {
6580 new_alloc_region->set_survivor();
6581 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6582 } else {
6583 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6584 }
6585 bool during_im = g1_policy()->during_initial_mark_pause();
6586 new_alloc_region->note_start_of_copying(during_im);
6587 return new_alloc_region;
6588 } else {
6589 g1_policy()->note_alloc_region_limit_reached(ap);
6590 }
6591 }
6592 return NULL;
6593 }
6594
6595 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6596 size_t allocated_bytes,
6597 GCAllocPurpose ap) {
6598 bool during_im = g1_policy()->during_initial_mark_pause();
6599 alloc_region->note_end_of_copying(during_im);
6600 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6601 if (ap == GCAllocForSurvived) {
6602 young_list()->add_survivor_region(alloc_region);
6603 } else {
6604 _old_set.add(alloc_region);
6605 }
6606 _hr_printer.retire(alloc_region);
6607 }
6608
6609 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6610 bool force) {
6611 assert(!force, "not supported for GC alloc regions");
6612 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6613 }
6614
6615 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6616 size_t allocated_bytes) {
6617 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6618 GCAllocForSurvived);
6619 }
6620
6621 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6622 bool force) {
6623 assert(!force, "not supported for GC alloc regions");
6624 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6625 }
6626
6627 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6628 size_t allocated_bytes) {
6629 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6630 GCAllocForTenured);
6631 }
6632 // Heap region set verification
6633
6634 class VerifyRegionListsClosure : public HeapRegionClosure {
6635 private:
6636 FreeRegionList* _free_list;
6637 OldRegionSet* _old_set;
6638 HumongousRegionSet* _humongous_set;
6639 uint _region_count;
6640
6641 public:
6642 VerifyRegionListsClosure(OldRegionSet* old_set,
6643 HumongousRegionSet* humongous_set,
6644 FreeRegionList* free_list) :
6645 _old_set(old_set), _humongous_set(humongous_set),
6646 _free_list(free_list), _region_count(0) { }
6647
6648 uint region_count() { return _region_count; }
6649
6650 bool doHeapRegion(HeapRegion* hr) {
6651 _region_count += 1;
6652
6653 if (hr->continuesHumongous()) {
6654 return false;
6655 }
6656
6657 if (hr->is_young()) {
6658 // TODO
6659 } else if (hr->startsHumongous()) {
6660 _humongous_set->verify_next_region(hr);
6661 } else if (hr->is_empty()) {
6662 _free_list->verify_next_region(hr);
6663 } else {
6664 _old_set->verify_next_region(hr);
6665 }
6666 return false;
6667 }
6668 };
6669
6670 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6671 HeapWord* bottom) {
6672 HeapWord* end = bottom + HeapRegion::GrainWords;
6673 MemRegion mr(bottom, end);
6674 assert(_g1_reserved.contains(mr), "invariant");
6675 // This might return NULL if the allocation fails
6676 return new HeapRegion(hrs_index, _bot_shared, mr);
6677 }
6678
6679 void G1CollectedHeap::verify_region_sets() {
6680 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6681
6682 // First, check the explicit lists.
6683 _free_list.verify();
6684 {
6685 // Given that a concurrent operation might be adding regions to
6686 // the secondary free list we have to take the lock before
6687 // verifying it.
6688 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6689 _secondary_free_list.verify();
6690 }
6691 _old_set.verify();
6692 _humongous_set.verify();
6693
6694 // If a concurrent region freeing operation is in progress it will
6695 // be difficult to correctly attributed any free regions we come
6696 // across to the correct free list given that they might belong to
6697 // one of several (free_list, secondary_free_list, any local lists,
6698 // etc.). So, if that's the case we will skip the rest of the
6699 // verification operation. Alternatively, waiting for the concurrent
6700 // operation to complete will have a non-trivial effect on the GC's
6701 // operation (no concurrent operation will last longer than the
6702 // interval between two calls to verification) and it might hide
6703 // any issues that we would like to catch during testing.
6704 if (free_regions_coming()) {
6705 return;
6706 }
6707
6708 // Make sure we append the secondary_free_list on the free_list so
6709 // that all free regions we will come across can be safely
6710 // attributed to the free_list.
6711 append_secondary_free_list_if_not_empty_with_lock();
6712
6713 // Finally, make sure that the region accounting in the lists is
6714 // consistent with what we see in the heap.
6715 _old_set.verify_start();
6716 _humongous_set.verify_start();
6717 _free_list.verify_start();
6718
6719 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6720 heap_region_iterate(&cl);
6721
6722 _old_set.verify_end();
6723 _humongous_set.verify_end();
6724 _free_list.verify_end();
6725 }
6726
6727 // Optimized nmethod scanning
6728
6729 class RegisterNMethodOopClosure: public OopClosure {
6730 G1CollectedHeap* _g1h;
6731 nmethod* _nm;
6732
6733 template <class T> void do_oop_work(T* p) {
6734 T heap_oop = oopDesc::load_heap_oop(p);
6735 if (!oopDesc::is_null(heap_oop)) {
6736 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6737 HeapRegion* hr = _g1h->heap_region_containing(obj);
6738 assert(!hr->continuesHumongous(),
6739 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6740 " starting at "HR_FORMAT,
6741 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6742
6743 // HeapRegion::add_strong_code_root() avoids adding duplicate
6744 // entries but having duplicates is OK since we "mark" nmethods
6745 // as visited when we scan the strong code root lists during the GC.
6746 hr->add_strong_code_root(_nm);
6747 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6748 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6749 _nm, HR_FORMAT_PARAMS(hr)));
6750 }
6751 }
6752
6753 public:
6754 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6755 _g1h(g1h), _nm(nm) {}
6756
6757 void do_oop(oop* p) { do_oop_work(p); }
6758 void do_oop(narrowOop* p) { do_oop_work(p); }
6759 };
6760
6761 class UnregisterNMethodOopClosure: public OopClosure {
6762 G1CollectedHeap* _g1h;
6763 nmethod* _nm;
6764
6765 template <class T> void do_oop_work(T* p) {
6766 T heap_oop = oopDesc::load_heap_oop(p);
6767 if (!oopDesc::is_null(heap_oop)) {
6768 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6769 HeapRegion* hr = _g1h->heap_region_containing(obj);
6770 assert(!hr->continuesHumongous(),
6771 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6772 " starting at "HR_FORMAT,
6773 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6774
6775 hr->remove_strong_code_root(_nm);
6776 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6777 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6778 _nm, HR_FORMAT_PARAMS(hr)));
6779 }
6780 }
6781
6782 public:
6783 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6784 _g1h(g1h), _nm(nm) {}
6785
6786 void do_oop(oop* p) { do_oop_work(p); }
6787 void do_oop(narrowOop* p) { do_oop_work(p); }
6788 };
6789
6790 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6791 CollectedHeap::register_nmethod(nm);
6792
6793 guarantee(nm != NULL, "sanity");
6794 RegisterNMethodOopClosure reg_cl(this, nm);
6795 nm->oops_do(®_cl);
6796 }
6797
6798 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6799 CollectedHeap::unregister_nmethod(nm);
6800
6801 guarantee(nm != NULL, "sanity");
6802 UnregisterNMethodOopClosure reg_cl(this, nm);
6803 nm->oops_do(®_cl, true);
6804 }
6805
6806 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6807 public:
6808 bool doHeapRegion(HeapRegion *hr) {
6809 assert(!hr->isHumongous(),
6810 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6811 HR_FORMAT_PARAMS(hr)));
6812 hr->migrate_strong_code_roots();
6813 return false;
6814 }
6815 };
6816
6817 void G1CollectedHeap::migrate_strong_code_roots() {
6818 MigrateCodeRootsHeapRegionClosure cl;
6819 double migrate_start = os::elapsedTime();
6820 collection_set_iterate(&cl);
6821 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6822 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6823 }
6824
6825 // Mark all the code roots that point into regions *not* in the
6826 // collection set.
6827 //
6828 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6829 // walking the the code roots lists of regions not in the collection
6830 // set. Suppose we have an nmethod (M) that points to objects in two
6831 // separate regions - one in the collection set (R1) and one not (R2).
6832 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6833 // nmethod M when walking the code roots for R1. When we come to scan
6834 // the code roots for R2, we would see that M is already marked and it
6835 // would be skipped and the objects in R2 that are referenced from M
6836 // would not be evacuated.
6837
6838 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6839
6840 class MarkStrongCodeRootOopClosure: public OopClosure {
6841 ConcurrentMark* _cm;
6842 HeapRegion* _hr;
6843 uint _worker_id;
6844
6845 template <class T> void do_oop_work(T* p) {
6846 T heap_oop = oopDesc::load_heap_oop(p);
6847 if (!oopDesc::is_null(heap_oop)) {
6848 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6849 // Only mark objects in the region (which is assumed
6850 // to be not in the collection set).
6851 if (_hr->is_in(obj)) {
6852 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6853 }
6854 }
6855 }
6856
6857 public:
6858 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6859 _cm(cm), _hr(hr), _worker_id(worker_id) {
6860 assert(!_hr->in_collection_set(), "sanity");
6861 }
6862
6863 void do_oop(narrowOop* p) { do_oop_work(p); }
6864 void do_oop(oop* p) { do_oop_work(p); }
6865 };
6866
6867 MarkStrongCodeRootOopClosure _oop_cl;
6868
6869 public:
6870 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6871 _oop_cl(cm, hr, worker_id) {}
6872
6873 void do_code_blob(CodeBlob* cb) {
6874 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6875 if (nm != NULL) {
6876 nm->oops_do(&_oop_cl);
6877 }
6878 }
6879 };
6880
6881 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6882 G1CollectedHeap* _g1h;
6883 uint _worker_id;
6884
6885 public:
6886 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6887 _g1h(g1h), _worker_id(worker_id) {}
6888
6889 bool doHeapRegion(HeapRegion *hr) {
6890 HeapRegionRemSet* hrrs = hr->rem_set();
6891 if (hr->continuesHumongous()) {
6892 // Code roots should never be attached to a continuation of a humongous region
6893 assert(hrrs->strong_code_roots_list_length() == 0,
6894 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6895 " starting at "HR_FORMAT", but has "INT32_FORMAT,
6896 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6897 hrrs->strong_code_roots_list_length()));
6898 return false;
6899 }
6900
6901 if (hr->in_collection_set()) {
6902 // Don't mark code roots into regions in the collection set here.
6903 // They will be marked when we scan them.
6904 return false;
6905 }
6906
6907 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6908 hr->strong_code_roots_do(&cb_cl);
6909 return false;
6910 }
6911 };
6912
6913 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6914 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6915 if (G1CollectedHeap::use_parallel_gc_threads()) {
6916 heap_region_par_iterate_chunked(&cl,
6917 worker_id,
6918 workers()->active_workers(),
6919 HeapRegion::ParMarkRootClaimValue);
6920 } else {
6921 heap_region_iterate(&cl);
6922 }
6923 }
6924
6925 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6926 G1CollectedHeap* _g1h;
6927
6928 public:
6929 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6930 _g1h(g1h) {}
6931
6932 void do_code_blob(CodeBlob* cb) {
6933 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6934 if (nm == NULL) {
6935 return;
6936 }
6937
6938 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6939 _g1h->register_nmethod(nm);
6940 }
6941 }
6942 };
6943
6944 void G1CollectedHeap::rebuild_strong_code_roots() {
6945 RebuildStrongCodeRootClosure blob_cl(this);
6946 CodeCache::blobs_do(&blob_cl);
6947 }