1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1YCTypes.hpp"
43 #include "gc_implementation/g1/heapRegion.inline.hpp"
44 #include "gc_implementation/g1/heapRegionRemSet.hpp"
45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
46 #include "gc_implementation/g1/vm_operations_g1.hpp"
47 #include "gc_implementation/shared/gcHeapSummary.hpp"
48 #include "gc_implementation/shared/gcTimer.hpp"
49 #include "gc_implementation/shared/gcTrace.hpp"
50 #include "gc_implementation/shared/gcTraceTime.hpp"
51 #include "gc_implementation/shared/isGCActiveMark.hpp"
52 #include "memory/gcLocker.inline.hpp"
53 #include "memory/genOopClosures.inline.hpp"
54 #include "memory/generationSpec.hpp"
55 #include "memory/referenceProcessor.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/oop.pcgc.inline.hpp"
58 #include "runtime/vmThread.hpp"
59
60 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
61
62 // turn it on so that the contents of the young list (scan-only /
63 // to-be-collected) are printed at "strategic" points before / during
64 // / after the collection --- this is useful for debugging
65 #define YOUNG_LIST_VERBOSE 0
66 // CURRENT STATUS
67 // This file is under construction. Search for "FIXME".
68
69 // INVARIANTS/NOTES
70 //
71 // All allocation activity covered by the G1CollectedHeap interface is
72 // serialized by acquiring the HeapLock. This happens in mem_allocate
73 // and allocate_new_tlab, which are the "entry" points to the
74 // allocation code from the rest of the JVM. (Note that this does not
75 // apply to TLAB allocation, which is not part of this interface: it
76 // is done by clients of this interface.)
77
78 // Notes on implementation of parallelism in different tasks.
79 //
80 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
81 // The number of GC workers is passed to heap_region_par_iterate_chunked().
82 // It does use run_task() which sets _n_workers in the task.
83 // G1ParTask executes g1_process_strong_roots() ->
84 // SharedHeap::process_strong_roots() which calls eventually to
85 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
86 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
87 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
88 //
89
90 // Local to this file.
91
92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
93 SuspendibleThreadSet* _sts;
94 G1RemSet* _g1rs;
95 ConcurrentG1Refine* _cg1r;
96 bool _concurrent;
97 public:
98 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
99 G1RemSet* g1rs,
100 ConcurrentG1Refine* cg1r) :
101 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
102 {}
103 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
104 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
105 // This path is executed by the concurrent refine or mutator threads,
106 // concurrently, and so we do not care if card_ptr contains references
107 // that point into the collection set.
108 assert(!oops_into_cset, "should be");
109
110 if (_concurrent && _sts->should_yield()) {
111 // Caller will actually yield.
112 return false;
113 }
114 // Otherwise, we finished successfully; return true.
115 return true;
116 }
117 void set_concurrent(bool b) { _concurrent = b; }
118 };
119
120
121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
122 int _calls;
123 G1CollectedHeap* _g1h;
124 CardTableModRefBS* _ctbs;
125 int _histo[256];
126 public:
127 ClearLoggedCardTableEntryClosure() :
128 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
129 {
130 for (int i = 0; i < 256; i++) _histo[i] = 0;
131 }
132 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
133 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
134 _calls++;
135 unsigned char* ujb = (unsigned char*)card_ptr;
136 int ind = (int)(*ujb);
137 _histo[ind]++;
138 *card_ptr = -1;
139 }
140 return true;
141 }
142 int calls() { return _calls; }
143 void print_histo() {
144 gclog_or_tty->print_cr("Card table value histogram:");
145 for (int i = 0; i < 256; i++) {
146 if (_histo[i] != 0) {
147 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
148 }
149 }
150 }
151 };
152
153 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
154 int _calls;
155 G1CollectedHeap* _g1h;
156 CardTableModRefBS* _ctbs;
157 public:
158 RedirtyLoggedCardTableEntryClosure() :
159 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
160
161 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
162 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
163 _calls++;
164 *card_ptr = 0;
165 }
166 return true;
167 }
168 int calls() { return _calls; }
169 };
170
171 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
172 public:
173 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
174 *card_ptr = CardTableModRefBS::dirty_card_val();
175 return true;
176 }
177 };
178
179 YoungList::YoungList(G1CollectedHeap* g1h) :
180 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
181 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
182 guarantee(check_list_empty(false), "just making sure...");
183 }
184
185 void YoungList::push_region(HeapRegion *hr) {
186 assert(!hr->is_young(), "should not already be young");
187 assert(hr->get_next_young_region() == NULL, "cause it should!");
188
189 hr->set_next_young_region(_head);
190 _head = hr;
191
192 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
193 ++_length;
194 }
195
196 void YoungList::add_survivor_region(HeapRegion* hr) {
197 assert(hr->is_survivor(), "should be flagged as survivor region");
198 assert(hr->get_next_young_region() == NULL, "cause it should!");
199
200 hr->set_next_young_region(_survivor_head);
201 if (_survivor_head == NULL) {
202 _survivor_tail = hr;
203 }
204 _survivor_head = hr;
205 ++_survivor_length;
206 }
207
208 void YoungList::empty_list(HeapRegion* list) {
209 while (list != NULL) {
210 HeapRegion* next = list->get_next_young_region();
211 list->set_next_young_region(NULL);
212 list->uninstall_surv_rate_group();
213 list->set_not_young();
214 list = next;
215 }
216 }
217
218 void YoungList::empty_list() {
219 assert(check_list_well_formed(), "young list should be well formed");
220
221 empty_list(_head);
222 _head = NULL;
223 _length = 0;
224
225 empty_list(_survivor_head);
226 _survivor_head = NULL;
227 _survivor_tail = NULL;
228 _survivor_length = 0;
229
230 _last_sampled_rs_lengths = 0;
231
232 assert(check_list_empty(false), "just making sure...");
233 }
234
235 bool YoungList::check_list_well_formed() {
236 bool ret = true;
237
238 uint length = 0;
239 HeapRegion* curr = _head;
240 HeapRegion* last = NULL;
241 while (curr != NULL) {
242 if (!curr->is_young()) {
243 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
244 "incorrectly tagged (y: %d, surv: %d)",
245 curr->bottom(), curr->end(),
246 curr->is_young(), curr->is_survivor());
247 ret = false;
248 }
249 ++length;
250 last = curr;
251 curr = curr->get_next_young_region();
252 }
253 ret = ret && (length == _length);
254
255 if (!ret) {
256 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
257 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
258 length, _length);
259 }
260
261 return ret;
262 }
263
264 bool YoungList::check_list_empty(bool check_sample) {
265 bool ret = true;
266
267 if (_length != 0) {
268 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
269 _length);
270 ret = false;
271 }
272 if (check_sample && _last_sampled_rs_lengths != 0) {
273 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
274 ret = false;
275 }
276 if (_head != NULL) {
277 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
278 ret = false;
279 }
280 if (!ret) {
281 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
282 }
283
284 return ret;
285 }
286
287 void
288 YoungList::rs_length_sampling_init() {
289 _sampled_rs_lengths = 0;
290 _curr = _head;
291 }
292
293 bool
294 YoungList::rs_length_sampling_more() {
295 return _curr != NULL;
296 }
297
298 void
299 YoungList::rs_length_sampling_next() {
300 assert( _curr != NULL, "invariant" );
301 size_t rs_length = _curr->rem_set()->occupied();
302
303 _sampled_rs_lengths += rs_length;
304
305 // The current region may not yet have been added to the
306 // incremental collection set (it gets added when it is
307 // retired as the current allocation region).
308 if (_curr->in_collection_set()) {
309 // Update the collection set policy information for this region
310 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
311 }
312
313 _curr = _curr->get_next_young_region();
314 if (_curr == NULL) {
315 _last_sampled_rs_lengths = _sampled_rs_lengths;
316 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
317 }
318 }
319
320 void
321 YoungList::reset_auxilary_lists() {
322 guarantee( is_empty(), "young list should be empty" );
323 assert(check_list_well_formed(), "young list should be well formed");
324
325 // Add survivor regions to SurvRateGroup.
326 _g1h->g1_policy()->note_start_adding_survivor_regions();
327 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
328
329 int young_index_in_cset = 0;
330 for (HeapRegion* curr = _survivor_head;
331 curr != NULL;
332 curr = curr->get_next_young_region()) {
333 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
334
335 // The region is a non-empty survivor so let's add it to
336 // the incremental collection set for the next evacuation
337 // pause.
338 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
339 young_index_in_cset += 1;
340 }
341 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
342 _g1h->g1_policy()->note_stop_adding_survivor_regions();
343
344 _head = _survivor_head;
345 _length = _survivor_length;
346 if (_survivor_head != NULL) {
347 assert(_survivor_tail != NULL, "cause it shouldn't be");
348 assert(_survivor_length > 0, "invariant");
349 _survivor_tail->set_next_young_region(NULL);
350 }
351
352 // Don't clear the survivor list handles until the start of
353 // the next evacuation pause - we need it in order to re-tag
354 // the survivor regions from this evacuation pause as 'young'
355 // at the start of the next.
356
357 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
358
359 assert(check_list_well_formed(), "young list should be well formed");
360 }
361
362 void YoungList::print() {
363 HeapRegion* lists[] = {_head, _survivor_head};
364 const char* names[] = {"YOUNG", "SURVIVOR"};
365
366 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
367 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
368 HeapRegion *curr = lists[list];
369 if (curr == NULL)
370 gclog_or_tty->print_cr(" empty");
371 while (curr != NULL) {
372 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
373 HR_FORMAT_PARAMS(curr),
374 curr->prev_top_at_mark_start(),
375 curr->next_top_at_mark_start(),
376 curr->age_in_surv_rate_group_cond());
377 curr = curr->get_next_young_region();
378 }
379 }
380
381 gclog_or_tty->print_cr("");
382 }
383
384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
385 {
386 // Claim the right to put the region on the dirty cards region list
387 // by installing a self pointer.
388 HeapRegion* next = hr->get_next_dirty_cards_region();
389 if (next == NULL) {
390 HeapRegion* res = (HeapRegion*)
391 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
392 NULL);
393 if (res == NULL) {
394 HeapRegion* head;
395 do {
396 // Put the region to the dirty cards region list.
397 head = _dirty_cards_region_list;
398 next = (HeapRegion*)
399 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
400 if (next == head) {
401 assert(hr->get_next_dirty_cards_region() == hr,
402 "hr->get_next_dirty_cards_region() != hr");
403 if (next == NULL) {
404 // The last region in the list points to itself.
405 hr->set_next_dirty_cards_region(hr);
406 } else {
407 hr->set_next_dirty_cards_region(next);
408 }
409 }
410 } while (next != head);
411 }
412 }
413 }
414
415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
416 {
417 HeapRegion* head;
418 HeapRegion* hr;
419 do {
420 head = _dirty_cards_region_list;
421 if (head == NULL) {
422 return NULL;
423 }
424 HeapRegion* new_head = head->get_next_dirty_cards_region();
425 if (head == new_head) {
426 // The last region.
427 new_head = NULL;
428 }
429 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
430 head);
431 } while (hr != head);
432 assert(hr != NULL, "invariant");
433 hr->set_next_dirty_cards_region(NULL);
434 return hr;
435 }
436
437 void G1CollectedHeap::stop_conc_gc_threads() {
438 _cg1r->stop();
439 _cmThread->stop();
440 }
441
442 #ifdef ASSERT
443 // A region is added to the collection set as it is retired
444 // so an address p can point to a region which will be in the
445 // collection set but has not yet been retired. This method
446 // therefore is only accurate during a GC pause after all
447 // regions have been retired. It is used for debugging
448 // to check if an nmethod has references to objects that can
449 // be move during a partial collection. Though it can be
450 // inaccurate, it is sufficient for G1 because the conservative
451 // implementation of is_scavengable() for G1 will indicate that
452 // all nmethods must be scanned during a partial collection.
453 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
454 HeapRegion* hr = heap_region_containing(p);
455 return hr != NULL && hr->in_collection_set();
456 }
457 #endif
458
459 // Returns true if the reference points to an object that
460 // can move in an incremental collection.
461 bool G1CollectedHeap::is_scavengable(const void* p) {
462 G1CollectedHeap* g1h = G1CollectedHeap::heap();
463 G1CollectorPolicy* g1p = g1h->g1_policy();
464 HeapRegion* hr = heap_region_containing(p);
465 if (hr == NULL) {
466 // null
467 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
468 return false;
469 } else {
470 return !hr->isHumongous();
471 }
472 }
473
474 void G1CollectedHeap::check_ct_logs_at_safepoint() {
475 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
476 CardTableModRefBS* ct_bs = g1_barrier_set();
477
478 // Count the dirty cards at the start.
479 CountNonCleanMemRegionClosure count1(this);
480 ct_bs->mod_card_iterate(&count1);
481 int orig_count = count1.n();
482
483 // First clear the logged cards.
484 ClearLoggedCardTableEntryClosure clear;
485 dcqs.set_closure(&clear);
486 dcqs.apply_closure_to_all_completed_buffers();
487 dcqs.iterate_closure_all_threads(false);
488 clear.print_histo();
489
490 // Now ensure that there's no dirty cards.
491 CountNonCleanMemRegionClosure count2(this);
492 ct_bs->mod_card_iterate(&count2);
493 if (count2.n() != 0) {
494 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
495 count2.n(), orig_count);
496 }
497 guarantee(count2.n() == 0, "Card table should be clean.");
498
499 RedirtyLoggedCardTableEntryClosure redirty;
500 JavaThread::dirty_card_queue_set().set_closure(&redirty);
501 dcqs.apply_closure_to_all_completed_buffers();
502 dcqs.iterate_closure_all_threads(false);
503 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
504 clear.calls(), orig_count);
505 guarantee(redirty.calls() == clear.calls(),
506 "Or else mechanism is broken.");
507
508 CountNonCleanMemRegionClosure count3(this);
509 ct_bs->mod_card_iterate(&count3);
510 if (count3.n() != orig_count) {
511 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
512 orig_count, count3.n());
513 guarantee(count3.n() >= orig_count, "Should have restored them all.");
514 }
515
516 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
517 }
518
519 // Private class members.
520
521 G1CollectedHeap* G1CollectedHeap::_g1h;
522
523 // Private methods.
524
525 HeapRegion*
526 G1CollectedHeap::new_region_try_secondary_free_list() {
527 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
528 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
529 if (!_secondary_free_list.is_empty()) {
530 if (G1ConcRegionFreeingVerbose) {
531 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
532 "secondary_free_list has %u entries",
533 _secondary_free_list.length());
534 }
535 // It looks as if there are free regions available on the
536 // secondary_free_list. Let's move them to the free_list and try
537 // again to allocate from it.
538 append_secondary_free_list();
539
540 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
541 "empty we should have moved at least one entry to the free_list");
542 HeapRegion* res = _free_list.remove_head();
543 if (G1ConcRegionFreeingVerbose) {
544 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
545 "allocated "HR_FORMAT" from secondary_free_list",
546 HR_FORMAT_PARAMS(res));
547 }
548 return res;
549 }
550
551 // Wait here until we get notified either when (a) there are no
552 // more free regions coming or (b) some regions have been moved on
553 // the secondary_free_list.
554 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
555 }
556
557 if (G1ConcRegionFreeingVerbose) {
558 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
559 "could not allocate from secondary_free_list");
560 }
561 return NULL;
562 }
563
564 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
565 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
566 "the only time we use this to allocate a humongous region is "
567 "when we are allocating a single humongous region");
568
569 HeapRegion* res;
570 if (G1StressConcRegionFreeing) {
571 if (!_secondary_free_list.is_empty()) {
572 if (G1ConcRegionFreeingVerbose) {
573 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
574 "forced to look at the secondary_free_list");
575 }
576 res = new_region_try_secondary_free_list();
577 if (res != NULL) {
578 return res;
579 }
580 }
581 }
582 res = _free_list.remove_head_or_null();
583 if (res == NULL) {
584 if (G1ConcRegionFreeingVerbose) {
585 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
586 "res == NULL, trying the secondary_free_list");
587 }
588 res = new_region_try_secondary_free_list();
589 }
590 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
591 // Currently, only attempts to allocate GC alloc regions set
592 // do_expand to true. So, we should only reach here during a
593 // safepoint. If this assumption changes we might have to
594 // reconsider the use of _expand_heap_after_alloc_failure.
595 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
596
597 ergo_verbose1(ErgoHeapSizing,
598 "attempt heap expansion",
599 ergo_format_reason("region allocation request failed")
600 ergo_format_byte("allocation request"),
601 word_size * HeapWordSize);
602 if (expand(word_size * HeapWordSize)) {
603 // Given that expand() succeeded in expanding the heap, and we
604 // always expand the heap by an amount aligned to the heap
605 // region size, the free list should in theory not be empty. So
606 // it would probably be OK to use remove_head(). But the extra
607 // check for NULL is unlikely to be a performance issue here (we
608 // just expanded the heap!) so let's just be conservative and
609 // use remove_head_or_null().
610 res = _free_list.remove_head_or_null();
611 } else {
612 _expand_heap_after_alloc_failure = false;
613 }
614 }
615 return res;
616 }
617
618 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
619 size_t word_size) {
620 assert(isHumongous(word_size), "word_size should be humongous");
621 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
622
623 uint first = G1_NULL_HRS_INDEX;
624 if (num_regions == 1) {
625 // Only one region to allocate, no need to go through the slower
626 // path. The caller will attempt the expansion if this fails, so
627 // let's not try to expand here too.
628 HeapRegion* hr = new_region(word_size, false /* do_expand */);
629 if (hr != NULL) {
630 first = hr->hrs_index();
631 } else {
632 first = G1_NULL_HRS_INDEX;
633 }
634 } else {
635 // We can't allocate humongous regions while cleanupComplete() is
636 // running, since some of the regions we find to be empty might not
637 // yet be added to the free list and it is not straightforward to
638 // know which list they are on so that we can remove them. Note
639 // that we only need to do this if we need to allocate more than
640 // one region to satisfy the current humongous allocation
641 // request. If we are only allocating one region we use the common
642 // region allocation code (see above).
643 wait_while_free_regions_coming();
644 append_secondary_free_list_if_not_empty_with_lock();
645
646 if (free_regions() >= num_regions) {
647 first = _hrs.find_contiguous(num_regions);
648 if (first != G1_NULL_HRS_INDEX) {
649 for (uint i = first; i < first + num_regions; ++i) {
650 HeapRegion* hr = region_at(i);
651 assert(hr->is_empty(), "sanity");
652 assert(is_on_master_free_list(hr), "sanity");
653 hr->set_pending_removal(true);
654 }
655 _free_list.remove_all_pending(num_regions);
656 }
657 }
658 }
659 return first;
660 }
661
662 HeapWord*
663 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
664 uint num_regions,
665 size_t word_size) {
666 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
667 assert(isHumongous(word_size), "word_size should be humongous");
668 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
669
670 // Index of last region in the series + 1.
671 uint last = first + num_regions;
672
673 // We need to initialize the region(s) we just discovered. This is
674 // a bit tricky given that it can happen concurrently with
675 // refinement threads refining cards on these regions and
676 // potentially wanting to refine the BOT as they are scanning
677 // those cards (this can happen shortly after a cleanup; see CR
678 // 6991377). So we have to set up the region(s) carefully and in
679 // a specific order.
680
681 // The word size sum of all the regions we will allocate.
682 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
683 assert(word_size <= word_size_sum, "sanity");
684
685 // This will be the "starts humongous" region.
686 HeapRegion* first_hr = region_at(first);
687 // The header of the new object will be placed at the bottom of
688 // the first region.
689 HeapWord* new_obj = first_hr->bottom();
690 // This will be the new end of the first region in the series that
691 // should also match the end of the last region in the series.
692 HeapWord* new_end = new_obj + word_size_sum;
693 // This will be the new top of the first region that will reflect
694 // this allocation.
695 HeapWord* new_top = new_obj + word_size;
696
697 // First, we need to zero the header of the space that we will be
698 // allocating. When we update top further down, some refinement
699 // threads might try to scan the region. By zeroing the header we
700 // ensure that any thread that will try to scan the region will
701 // come across the zero klass word and bail out.
702 //
703 // NOTE: It would not have been correct to have used
704 // CollectedHeap::fill_with_object() and make the space look like
705 // an int array. The thread that is doing the allocation will
706 // later update the object header to a potentially different array
707 // type and, for a very short period of time, the klass and length
708 // fields will be inconsistent. This could cause a refinement
709 // thread to calculate the object size incorrectly.
710 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
711
712 // We will set up the first region as "starts humongous". This
713 // will also update the BOT covering all the regions to reflect
714 // that there is a single object that starts at the bottom of the
715 // first region.
716 first_hr->set_startsHumongous(new_top, new_end);
717
718 // Then, if there are any, we will set up the "continues
719 // humongous" regions.
720 HeapRegion* hr = NULL;
721 for (uint i = first + 1; i < last; ++i) {
722 hr = region_at(i);
723 hr->set_continuesHumongous(first_hr);
724 }
725 // If we have "continues humongous" regions (hr != NULL), then the
726 // end of the last one should match new_end.
727 assert(hr == NULL || hr->end() == new_end, "sanity");
728
729 // Up to this point no concurrent thread would have been able to
730 // do any scanning on any region in this series. All the top
731 // fields still point to bottom, so the intersection between
732 // [bottom,top] and [card_start,card_end] will be empty. Before we
733 // update the top fields, we'll do a storestore to make sure that
734 // no thread sees the update to top before the zeroing of the
735 // object header and the BOT initialization.
736 OrderAccess::storestore();
737
738 // Now that the BOT and the object header have been initialized,
739 // we can update top of the "starts humongous" region.
740 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
741 "new_top should be in this region");
742 first_hr->set_top(new_top);
743 if (_hr_printer.is_active()) {
744 HeapWord* bottom = first_hr->bottom();
745 HeapWord* end = first_hr->orig_end();
746 if ((first + 1) == last) {
747 // the series has a single humongous region
748 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
749 } else {
750 // the series has more than one humongous regions
751 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
752 }
753 }
754
755 // Now, we will update the top fields of the "continues humongous"
756 // regions. The reason we need to do this is that, otherwise,
757 // these regions would look empty and this will confuse parts of
758 // G1. For example, the code that looks for a consecutive number
759 // of empty regions will consider them empty and try to
760 // re-allocate them. We can extend is_empty() to also include
761 // !continuesHumongous(), but it is easier to just update the top
762 // fields here. The way we set top for all regions (i.e., top ==
763 // end for all regions but the last one, top == new_top for the
764 // last one) is actually used when we will free up the humongous
765 // region in free_humongous_region().
766 hr = NULL;
767 for (uint i = first + 1; i < last; ++i) {
768 hr = region_at(i);
769 if ((i + 1) == last) {
770 // last continues humongous region
771 assert(hr->bottom() < new_top && new_top <= hr->end(),
772 "new_top should fall on this region");
773 hr->set_top(new_top);
774 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
775 } else {
776 // not last one
777 assert(new_top > hr->end(), "new_top should be above this region");
778 hr->set_top(hr->end());
779 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
780 }
781 }
782 // If we have continues humongous regions (hr != NULL), then the
783 // end of the last one should match new_end and its top should
784 // match new_top.
785 assert(hr == NULL ||
786 (hr->end() == new_end && hr->top() == new_top), "sanity");
787
788 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
789 _summary_bytes_used += first_hr->used();
790 _humongous_set.add(first_hr);
791
792 return new_obj;
793 }
794
795 // If could fit into free regions w/o expansion, try.
796 // Otherwise, if can expand, do so.
797 // Otherwise, if using ex regions might help, try with ex given back.
798 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
799 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
800
801 verify_region_sets_optional();
802
803 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
804 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
805 uint x_num = expansion_regions();
806 uint fs = _hrs.free_suffix();
807 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
808 if (first == G1_NULL_HRS_INDEX) {
809 // The only thing we can do now is attempt expansion.
810 if (fs + x_num >= num_regions) {
811 // If the number of regions we're trying to allocate for this
812 // object is at most the number of regions in the free suffix,
813 // then the call to humongous_obj_allocate_find_first() above
814 // should have succeeded and we wouldn't be here.
815 //
816 // We should only be trying to expand when the free suffix is
817 // not sufficient for the object _and_ we have some expansion
818 // room available.
819 assert(num_regions > fs, "earlier allocation should have succeeded");
820
821 ergo_verbose1(ErgoHeapSizing,
822 "attempt heap expansion",
823 ergo_format_reason("humongous allocation request failed")
824 ergo_format_byte("allocation request"),
825 word_size * HeapWordSize);
826 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
827 // Even though the heap was expanded, it might not have
828 // reached the desired size. So, we cannot assume that the
829 // allocation will succeed.
830 first = humongous_obj_allocate_find_first(num_regions, word_size);
831 }
832 }
833 }
834
835 HeapWord* result = NULL;
836 if (first != G1_NULL_HRS_INDEX) {
837 result =
838 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
839 assert(result != NULL, "it should always return a valid result");
840
841 // A successful humongous object allocation changes the used space
842 // information of the old generation so we need to recalculate the
843 // sizes and update the jstat counters here.
844 g1mm()->update_sizes();
845 }
846
847 verify_region_sets_optional();
848
849 return result;
850 }
851
852 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
853 assert_heap_not_locked_and_not_at_safepoint();
854 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
855
856 unsigned int dummy_gc_count_before;
857 int dummy_gclocker_retry_count = 0;
858 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
859 }
860
861 HeapWord*
862 G1CollectedHeap::mem_allocate(size_t word_size,
863 bool* gc_overhead_limit_was_exceeded) {
864 assert_heap_not_locked_and_not_at_safepoint();
865
866 // Loop until the allocation is satisfied, or unsatisfied after GC.
867 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
868 unsigned int gc_count_before;
869
870 HeapWord* result = NULL;
871 if (!isHumongous(word_size)) {
872 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
873 } else {
874 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
875 }
876 if (result != NULL) {
877 return result;
878 }
879
880 // Create the garbage collection operation...
881 VM_G1CollectForAllocation op(gc_count_before, word_size);
882 // ...and get the VM thread to execute it.
883 VMThread::execute(&op);
884
885 if (op.prologue_succeeded() && op.pause_succeeded()) {
886 // If the operation was successful we'll return the result even
887 // if it is NULL. If the allocation attempt failed immediately
888 // after a Full GC, it's unlikely we'll be able to allocate now.
889 HeapWord* result = op.result();
890 if (result != NULL && !isHumongous(word_size)) {
891 // Allocations that take place on VM operations do not do any
892 // card dirtying and we have to do it here. We only have to do
893 // this for non-humongous allocations, though.
894 dirty_young_block(result, word_size);
895 }
896 return result;
897 } else {
898 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
899 return NULL;
900 }
901 assert(op.result() == NULL,
902 "the result should be NULL if the VM op did not succeed");
903 }
904
905 // Give a warning if we seem to be looping forever.
906 if ((QueuedAllocationWarningCount > 0) &&
907 (try_count % QueuedAllocationWarningCount == 0)) {
908 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 return NULL;
914 }
915
916 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
917 unsigned int *gc_count_before_ret,
918 int* gclocker_retry_count_ret) {
919 // Make sure you read the note in attempt_allocation_humongous().
920
921 assert_heap_not_locked_and_not_at_safepoint();
922 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
923 "be called for humongous allocation requests");
924
925 // We should only get here after the first-level allocation attempt
926 // (attempt_allocation()) failed to allocate.
927
928 // We will loop until a) we manage to successfully perform the
929 // allocation or b) we successfully schedule a collection which
930 // fails to perform the allocation. b) is the only case when we'll
931 // return NULL.
932 HeapWord* result = NULL;
933 for (int try_count = 1; /* we'll return */; try_count += 1) {
934 bool should_try_gc;
935 unsigned int gc_count_before;
936
937 {
938 MutexLockerEx x(Heap_lock);
939
940 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
941 false /* bot_updates */);
942 if (result != NULL) {
943 return result;
944 }
945
946 // If we reach here, attempt_allocation_locked() above failed to
947 // allocate a new region. So the mutator alloc region should be NULL.
948 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
949
950 if (GC_locker::is_active_and_needs_gc()) {
951 if (g1_policy()->can_expand_young_list()) {
952 // No need for an ergo verbose message here,
953 // can_expand_young_list() does this when it returns true.
954 result = _mutator_alloc_region.attempt_allocation_force(word_size,
955 false /* bot_updates */);
956 if (result != NULL) {
957 return result;
958 }
959 }
960 should_try_gc = false;
961 } else {
962 // The GCLocker may not be active but the GCLocker initiated
963 // GC may not yet have been performed (GCLocker::needs_gc()
964 // returns true). In this case we do not try this GC and
965 // wait until the GCLocker initiated GC is performed, and
966 // then retry the allocation.
967 if (GC_locker::needs_gc()) {
968 should_try_gc = false;
969 } else {
970 // Read the GC count while still holding the Heap_lock.
971 gc_count_before = total_collections();
972 should_try_gc = true;
973 }
974 }
975 }
976
977 if (should_try_gc) {
978 bool succeeded;
979 result = do_collection_pause(word_size, gc_count_before, &succeeded,
980 GCCause::_g1_inc_collection_pause);
981 if (result != NULL) {
982 assert(succeeded, "only way to get back a non-NULL result");
983 return result;
984 }
985
986 if (succeeded) {
987 // If we get here we successfully scheduled a collection which
988 // failed to allocate. No point in trying to allocate
989 // further. We'll just return NULL.
990 MutexLockerEx x(Heap_lock);
991 *gc_count_before_ret = total_collections();
992 return NULL;
993 }
994 } else {
995 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
996 MutexLockerEx x(Heap_lock);
997 *gc_count_before_ret = total_collections();
998 return NULL;
999 }
1000 // The GCLocker is either active or the GCLocker initiated
1001 // GC has not yet been performed. Stall until it is and
1002 // then retry the allocation.
1003 GC_locker::stall_until_clear();
1004 (*gclocker_retry_count_ret) += 1;
1005 }
1006
1007 // We can reach here if we were unsuccessful in scheduling a
1008 // collection (because another thread beat us to it) or if we were
1009 // stalled due to the GC locker. In either can we should retry the
1010 // allocation attempt in case another thread successfully
1011 // performed a collection and reclaimed enough space. We do the
1012 // first attempt (without holding the Heap_lock) here and the
1013 // follow-on attempt will be at the start of the next loop
1014 // iteration (after taking the Heap_lock).
1015 result = _mutator_alloc_region.attempt_allocation(word_size,
1016 false /* bot_updates */);
1017 if (result != NULL) {
1018 return result;
1019 }
1020
1021 // Give a warning if we seem to be looping forever.
1022 if ((QueuedAllocationWarningCount > 0) &&
1023 (try_count % QueuedAllocationWarningCount == 0)) {
1024 warning("G1CollectedHeap::attempt_allocation_slow() "
1025 "retries %d times", try_count);
1026 }
1027 }
1028
1029 ShouldNotReachHere();
1030 return NULL;
1031 }
1032
1033 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1034 unsigned int * gc_count_before_ret,
1035 int* gclocker_retry_count_ret) {
1036 // The structure of this method has a lot of similarities to
1037 // attempt_allocation_slow(). The reason these two were not merged
1038 // into a single one is that such a method would require several "if
1039 // allocation is not humongous do this, otherwise do that"
1040 // conditional paths which would obscure its flow. In fact, an early
1041 // version of this code did use a unified method which was harder to
1042 // follow and, as a result, it had subtle bugs that were hard to
1043 // track down. So keeping these two methods separate allows each to
1044 // be more readable. It will be good to keep these two in sync as
1045 // much as possible.
1046
1047 assert_heap_not_locked_and_not_at_safepoint();
1048 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1049 "should only be called for humongous allocations");
1050
1051 // Humongous objects can exhaust the heap quickly, so we should check if we
1052 // need to start a marking cycle at each humongous object allocation. We do
1053 // the check before we do the actual allocation. The reason for doing it
1054 // before the allocation is that we avoid having to keep track of the newly
1055 // allocated memory while we do a GC.
1056 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1057 word_size)) {
1058 collect(GCCause::_g1_humongous_allocation);
1059 }
1060
1061 // We will loop until a) we manage to successfully perform the
1062 // allocation or b) we successfully schedule a collection which
1063 // fails to perform the allocation. b) is the only case when we'll
1064 // return NULL.
1065 HeapWord* result = NULL;
1066 for (int try_count = 1; /* we'll return */; try_count += 1) {
1067 bool should_try_gc;
1068 unsigned int gc_count_before;
1069
1070 {
1071 MutexLockerEx x(Heap_lock);
1072
1073 // Given that humongous objects are not allocated in young
1074 // regions, we'll first try to do the allocation without doing a
1075 // collection hoping that there's enough space in the heap.
1076 result = humongous_obj_allocate(word_size);
1077 if (result != NULL) {
1078 return result;
1079 }
1080
1081 if (GC_locker::is_active_and_needs_gc()) {
1082 should_try_gc = false;
1083 } else {
1084 // The GCLocker may not be active but the GCLocker initiated
1085 // GC may not yet have been performed (GCLocker::needs_gc()
1086 // returns true). In this case we do not try this GC and
1087 // wait until the GCLocker initiated GC is performed, and
1088 // then retry the allocation.
1089 if (GC_locker::needs_gc()) {
1090 should_try_gc = false;
1091 } else {
1092 // Read the GC count while still holding the Heap_lock.
1093 gc_count_before = total_collections();
1094 should_try_gc = true;
1095 }
1096 }
1097 }
1098
1099 if (should_try_gc) {
1100 // If we failed to allocate the humongous object, we should try to
1101 // do a collection pause (if we're allowed) in case it reclaims
1102 // enough space for the allocation to succeed after the pause.
1103
1104 bool succeeded;
1105 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1106 GCCause::_g1_humongous_allocation);
1107 if (result != NULL) {
1108 assert(succeeded, "only way to get back a non-NULL result");
1109 return result;
1110 }
1111
1112 if (succeeded) {
1113 // If we get here we successfully scheduled a collection which
1114 // failed to allocate. No point in trying to allocate
1115 // further. We'll just return NULL.
1116 MutexLockerEx x(Heap_lock);
1117 *gc_count_before_ret = total_collections();
1118 return NULL;
1119 }
1120 } else {
1121 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1122 MutexLockerEx x(Heap_lock);
1123 *gc_count_before_ret = total_collections();
1124 return NULL;
1125 }
1126 // The GCLocker is either active or the GCLocker initiated
1127 // GC has not yet been performed. Stall until it is and
1128 // then retry the allocation.
1129 GC_locker::stall_until_clear();
1130 (*gclocker_retry_count_ret) += 1;
1131 }
1132
1133 // We can reach here if we were unsuccessful in scheduling a
1134 // collection (because another thread beat us to it) or if we were
1135 // stalled due to the GC locker. In either can we should retry the
1136 // allocation attempt in case another thread successfully
1137 // performed a collection and reclaimed enough space. Give a
1138 // warning if we seem to be looping forever.
1139
1140 if ((QueuedAllocationWarningCount > 0) &&
1141 (try_count % QueuedAllocationWarningCount == 0)) {
1142 warning("G1CollectedHeap::attempt_allocation_humongous() "
1143 "retries %d times", try_count);
1144 }
1145 }
1146
1147 ShouldNotReachHere();
1148 return NULL;
1149 }
1150
1151 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1152 bool expect_null_mutator_alloc_region) {
1153 assert_at_safepoint(true /* should_be_vm_thread */);
1154 assert(_mutator_alloc_region.get() == NULL ||
1155 !expect_null_mutator_alloc_region,
1156 "the current alloc region was unexpectedly found to be non-NULL");
1157
1158 if (!isHumongous(word_size)) {
1159 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1160 false /* bot_updates */);
1161 } else {
1162 HeapWord* result = humongous_obj_allocate(word_size);
1163 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1164 g1_policy()->set_initiate_conc_mark_if_possible();
1165 }
1166 return result;
1167 }
1168
1169 ShouldNotReachHere();
1170 }
1171
1172 class PostMCRemSetClearClosure: public HeapRegionClosure {
1173 G1CollectedHeap* _g1h;
1174 ModRefBarrierSet* _mr_bs;
1175 public:
1176 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1177 _g1h(g1h), _mr_bs(mr_bs) {}
1178
1179 bool doHeapRegion(HeapRegion* r) {
1180 HeapRegionRemSet* hrrs = r->rem_set();
1181
1182 if (r->continuesHumongous()) {
1183 // We'll assert that the strong code root list and RSet is empty
1184 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1185 assert(hrrs->occupied() == 0, "RSet should be empty");
1186 return false;
1187 }
1188
1189 _g1h->reset_gc_time_stamps(r);
1190 hrrs->clear();
1191 // You might think here that we could clear just the cards
1192 // corresponding to the used region. But no: if we leave a dirty card
1193 // in a region we might allocate into, then it would prevent that card
1194 // from being enqueued, and cause it to be missed.
1195 // Re: the performance cost: we shouldn't be doing full GC anyway!
1196 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1197
1198 return false;
1199 }
1200 };
1201
1202 void G1CollectedHeap::clear_rsets_post_compaction() {
1203 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1204 heap_region_iterate(&rs_clear);
1205 }
1206
1207 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1208 G1CollectedHeap* _g1h;
1209 UpdateRSOopClosure _cl;
1210 int _worker_i;
1211 public:
1212 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1213 _cl(g1->g1_rem_set(), worker_i),
1214 _worker_i(worker_i),
1215 _g1h(g1)
1216 { }
1217
1218 bool doHeapRegion(HeapRegion* r) {
1219 if (!r->continuesHumongous()) {
1220 _cl.set_from(r);
1221 r->oop_iterate(&_cl);
1222 }
1223 return false;
1224 }
1225 };
1226
1227 class ParRebuildRSTask: public AbstractGangTask {
1228 G1CollectedHeap* _g1;
1229 public:
1230 ParRebuildRSTask(G1CollectedHeap* g1)
1231 : AbstractGangTask("ParRebuildRSTask"),
1232 _g1(g1)
1233 { }
1234
1235 void work(uint worker_id) {
1236 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1237 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1238 _g1->workers()->active_workers(),
1239 HeapRegion::RebuildRSClaimValue);
1240 }
1241 };
1242
1243 class PostCompactionPrinterClosure: public HeapRegionClosure {
1244 private:
1245 G1HRPrinter* _hr_printer;
1246 public:
1247 bool doHeapRegion(HeapRegion* hr) {
1248 assert(!hr->is_young(), "not expecting to find young regions");
1249 // We only generate output for non-empty regions.
1250 if (!hr->is_empty()) {
1251 if (!hr->isHumongous()) {
1252 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1253 } else if (hr->startsHumongous()) {
1254 if (hr->region_num() == 1) {
1255 // single humongous region
1256 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1257 } else {
1258 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1259 }
1260 } else {
1261 assert(hr->continuesHumongous(), "only way to get here");
1262 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1263 }
1264 }
1265 return false;
1266 }
1267
1268 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1269 : _hr_printer(hr_printer) { }
1270 };
1271
1272 void G1CollectedHeap::print_hrs_post_compaction() {
1273 PostCompactionPrinterClosure cl(hr_printer());
1274 heap_region_iterate(&cl);
1275 }
1276
1277 bool G1CollectedHeap::do_collection(bool explicit_gc,
1278 bool clear_all_soft_refs,
1279 size_t word_size) {
1280 assert_at_safepoint(true /* should_be_vm_thread */);
1281
1282 if (GC_locker::check_active_before_gc()) {
1283 return false;
1284 }
1285
1286 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1287 gc_timer->register_gc_start(os::elapsed_counter());
1288
1289 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1290 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1291
1292 SvcGCMarker sgcm(SvcGCMarker::FULL);
1293 ResourceMark rm;
1294
1295 print_heap_before_gc();
1296 trace_heap_before_gc(gc_tracer);
1297
1298 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1299
1300 HRSPhaseSetter x(HRSPhaseFullGC);
1301 verify_region_sets_optional();
1302
1303 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1304 collector_policy()->should_clear_all_soft_refs();
1305
1306 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1307
1308 {
1309 IsGCActiveMark x;
1310
1311 // Timing
1312 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1313 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1314 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1315
1316 {
1317 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1318 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1319 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1320
1321 double start = os::elapsedTime();
1322 g1_policy()->record_full_collection_start();
1323
1324 // Note: When we have a more flexible GC logging framework that
1325 // allows us to add optional attributes to a GC log record we
1326 // could consider timing and reporting how long we wait in the
1327 // following two methods.
1328 wait_while_free_regions_coming();
1329 // If we start the compaction before the CM threads finish
1330 // scanning the root regions we might trip them over as we'll
1331 // be moving objects / updating references. So let's wait until
1332 // they are done. By telling them to abort, they should complete
1333 // early.
1334 _cm->root_regions()->abort();
1335 _cm->root_regions()->wait_until_scan_finished();
1336 append_secondary_free_list_if_not_empty_with_lock();
1337
1338 gc_prologue(true);
1339 increment_total_collections(true /* full gc */);
1340 increment_old_marking_cycles_started();
1341
1342 assert(used() == recalculate_used(), "Should be equal");
1343
1344 verify_before_gc();
1345
1346 pre_full_gc_dump(gc_timer);
1347
1348 COMPILER2_PRESENT(DerivedPointerTable::clear());
1349
1350 // Disable discovery and empty the discovered lists
1351 // for the CM ref processor.
1352 ref_processor_cm()->disable_discovery();
1353 ref_processor_cm()->abandon_partial_discovery();
1354 ref_processor_cm()->verify_no_references_recorded();
1355
1356 // Abandon current iterations of concurrent marking and concurrent
1357 // refinement, if any are in progress. We have to do this before
1358 // wait_until_scan_finished() below.
1359 concurrent_mark()->abort();
1360
1361 // Make sure we'll choose a new allocation region afterwards.
1362 release_mutator_alloc_region();
1363 abandon_gc_alloc_regions();
1364 g1_rem_set()->cleanupHRRS();
1365
1366 // We should call this after we retire any currently active alloc
1367 // regions so that all the ALLOC / RETIRE events are generated
1368 // before the start GC event.
1369 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1370
1371 // We may have added regions to the current incremental collection
1372 // set between the last GC or pause and now. We need to clear the
1373 // incremental collection set and then start rebuilding it afresh
1374 // after this full GC.
1375 abandon_collection_set(g1_policy()->inc_cset_head());
1376 g1_policy()->clear_incremental_cset();
1377 g1_policy()->stop_incremental_cset_building();
1378
1379 tear_down_region_sets(false /* free_list_only */);
1380 g1_policy()->set_gcs_are_young(true);
1381
1382 // See the comments in g1CollectedHeap.hpp and
1383 // G1CollectedHeap::ref_processing_init() about
1384 // how reference processing currently works in G1.
1385
1386 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1387 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1388
1389 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1390 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1391
1392 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1393 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1394
1395 // Do collection work
1396 {
1397 HandleMark hm; // Discard invalid handles created during gc
1398 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1399 }
1400
1401 assert(free_regions() == 0, "we should not have added any free regions");
1402 rebuild_region_sets(false /* free_list_only */);
1403
1404 // Enqueue any discovered reference objects that have
1405 // not been removed from the discovered lists.
1406 ref_processor_stw()->enqueue_discovered_references();
1407
1408 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1409
1410 MemoryService::track_memory_usage();
1411
1412 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1413 ref_processor_stw()->verify_no_references_recorded();
1414
1415 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1416 ClassLoaderDataGraph::purge();
1417 MetaspaceAux::verify_metrics();
1418
1419 // Note: since we've just done a full GC, concurrent
1420 // marking is no longer active. Therefore we need not
1421 // re-enable reference discovery for the CM ref processor.
1422 // That will be done at the start of the next marking cycle.
1423 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1424 ref_processor_cm()->verify_no_references_recorded();
1425
1426 reset_gc_time_stamp();
1427 // Since everything potentially moved, we will clear all remembered
1428 // sets, and clear all cards. Later we will rebuild remembered
1429 // sets. We will also reset the GC time stamps of the regions.
1430 clear_rsets_post_compaction();
1431 check_gc_time_stamps();
1432
1433 // Resize the heap if necessary.
1434 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1435
1436 if (_hr_printer.is_active()) {
1437 // We should do this after we potentially resize the heap so
1438 // that all the COMMIT / UNCOMMIT events are generated before
1439 // the end GC event.
1440
1441 print_hrs_post_compaction();
1442 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1443 }
1444
1445 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1446 if (hot_card_cache->use_cache()) {
1447 hot_card_cache->reset_card_counts();
1448 hot_card_cache->reset_hot_cache();
1449 }
1450
1451 // Rebuild remembered sets of all regions.
1452 if (G1CollectedHeap::use_parallel_gc_threads()) {
1453 uint n_workers =
1454 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1455 workers()->active_workers(),
1456 Threads::number_of_non_daemon_threads());
1457 assert(UseDynamicNumberOfGCThreads ||
1458 n_workers == workers()->total_workers(),
1459 "If not dynamic should be using all the workers");
1460 workers()->set_active_workers(n_workers);
1461 // Set parallel threads in the heap (_n_par_threads) only
1462 // before a parallel phase and always reset it to 0 after
1463 // the phase so that the number of parallel threads does
1464 // no get carried forward to a serial phase where there
1465 // may be code that is "possibly_parallel".
1466 set_par_threads(n_workers);
1467
1468 ParRebuildRSTask rebuild_rs_task(this);
1469 assert(check_heap_region_claim_values(
1470 HeapRegion::InitialClaimValue), "sanity check");
1471 assert(UseDynamicNumberOfGCThreads ||
1472 workers()->active_workers() == workers()->total_workers(),
1473 "Unless dynamic should use total workers");
1474 // Use the most recent number of active workers
1475 assert(workers()->active_workers() > 0,
1476 "Active workers not properly set");
1477 set_par_threads(workers()->active_workers());
1478 workers()->run_task(&rebuild_rs_task);
1479 set_par_threads(0);
1480 assert(check_heap_region_claim_values(
1481 HeapRegion::RebuildRSClaimValue), "sanity check");
1482 reset_heap_region_claim_values();
1483 } else {
1484 RebuildRSOutOfRegionClosure rebuild_rs(this);
1485 heap_region_iterate(&rebuild_rs);
1486 }
1487
1488 // Rebuild the strong code root lists for each region
1489 rebuild_strong_code_roots();
1490
1491 if (true) { // FIXME
1492 MetaspaceGC::compute_new_size();
1493 }
1494
1495 #ifdef TRACESPINNING
1496 ParallelTaskTerminator::print_termination_counts();
1497 #endif
1498
1499 // Discard all rset updates
1500 JavaThread::dirty_card_queue_set().abandon_logs();
1501 assert(!G1DeferredRSUpdate
1502 || (G1DeferredRSUpdate &&
1503 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1504
1505 _young_list->reset_sampled_info();
1506 // At this point there should be no regions in the
1507 // entire heap tagged as young.
1508 assert(check_young_list_empty(true /* check_heap */),
1509 "young list should be empty at this point");
1510
1511 // Update the number of full collections that have been completed.
1512 increment_old_marking_cycles_completed(false /* concurrent */);
1513
1514 _hrs.verify_optional();
1515 verify_region_sets_optional();
1516
1517 verify_after_gc();
1518
1519 // Start a new incremental collection set for the next pause
1520 assert(g1_policy()->collection_set() == NULL, "must be");
1521 g1_policy()->start_incremental_cset_building();
1522
1523 // Clear the _cset_fast_test bitmap in anticipation of adding
1524 // regions to the incremental collection set for the next
1525 // evacuation pause.
1526 clear_cset_fast_test();
1527
1528 init_mutator_alloc_region();
1529
1530 double end = os::elapsedTime();
1531 g1_policy()->record_full_collection_end();
1532
1533 if (G1Log::fine()) {
1534 g1_policy()->print_heap_transition();
1535 }
1536
1537 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1538 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1539 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1540 // before any GC notifications are raised.
1541 g1mm()->update_sizes();
1542
1543 gc_epilogue(true);
1544 }
1545
1546 if (G1Log::finer()) {
1547 g1_policy()->print_detailed_heap_transition(true /* full */);
1548 }
1549
1550 print_heap_after_gc();
1551 trace_heap_after_gc(gc_tracer);
1552
1553 post_full_gc_dump(gc_timer);
1554
1555 gc_timer->register_gc_end(os::elapsed_counter());
1556 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1557 }
1558
1559 return true;
1560 }
1561
1562 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1563 // do_collection() will return whether it succeeded in performing
1564 // the GC. Currently, there is no facility on the
1565 // do_full_collection() API to notify the caller than the collection
1566 // did not succeed (e.g., because it was locked out by the GC
1567 // locker). So, right now, we'll ignore the return value.
1568 bool dummy = do_collection(true, /* explicit_gc */
1569 clear_all_soft_refs,
1570 0 /* word_size */);
1571 }
1572
1573 // This code is mostly copied from TenuredGeneration.
1574 void
1575 G1CollectedHeap::
1576 resize_if_necessary_after_full_collection(size_t word_size) {
1577 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1578
1579 // Include the current allocation, if any, and bytes that will be
1580 // pre-allocated to support collections, as "used".
1581 const size_t used_after_gc = used();
1582 const size_t capacity_after_gc = capacity();
1583 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1584
1585 // This is enforced in arguments.cpp.
1586 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1587 "otherwise the code below doesn't make sense");
1588
1589 // We don't have floating point command-line arguments
1590 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1591 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1592 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1593 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1594
1595 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1596 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1597
1598 // We have to be careful here as these two calculations can overflow
1599 // 32-bit size_t's.
1600 double used_after_gc_d = (double) used_after_gc;
1601 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1602 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1603
1604 // Let's make sure that they are both under the max heap size, which
1605 // by default will make them fit into a size_t.
1606 double desired_capacity_upper_bound = (double) max_heap_size;
1607 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1608 desired_capacity_upper_bound);
1609 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1610 desired_capacity_upper_bound);
1611
1612 // We can now safely turn them into size_t's.
1613 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1614 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1615
1616 // This assert only makes sense here, before we adjust them
1617 // with respect to the min and max heap size.
1618 assert(minimum_desired_capacity <= maximum_desired_capacity,
1619 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1620 "maximum_desired_capacity = "SIZE_FORMAT,
1621 minimum_desired_capacity, maximum_desired_capacity));
1622
1623 // Should not be greater than the heap max size. No need to adjust
1624 // it with respect to the heap min size as it's a lower bound (i.e.,
1625 // we'll try to make the capacity larger than it, not smaller).
1626 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1627 // Should not be less than the heap min size. No need to adjust it
1628 // with respect to the heap max size as it's an upper bound (i.e.,
1629 // we'll try to make the capacity smaller than it, not greater).
1630 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1631
1632 if (capacity_after_gc < minimum_desired_capacity) {
1633 // Don't expand unless it's significant
1634 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1635 ergo_verbose4(ErgoHeapSizing,
1636 "attempt heap expansion",
1637 ergo_format_reason("capacity lower than "
1638 "min desired capacity after Full GC")
1639 ergo_format_byte("capacity")
1640 ergo_format_byte("occupancy")
1641 ergo_format_byte_perc("min desired capacity"),
1642 capacity_after_gc, used_after_gc,
1643 minimum_desired_capacity, (double) MinHeapFreeRatio);
1644 expand(expand_bytes);
1645
1646 // No expansion, now see if we want to shrink
1647 } else if (capacity_after_gc > maximum_desired_capacity) {
1648 // Capacity too large, compute shrinking size
1649 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1650 ergo_verbose4(ErgoHeapSizing,
1651 "attempt heap shrinking",
1652 ergo_format_reason("capacity higher than "
1653 "max desired capacity after Full GC")
1654 ergo_format_byte("capacity")
1655 ergo_format_byte("occupancy")
1656 ergo_format_byte_perc("max desired capacity"),
1657 capacity_after_gc, used_after_gc,
1658 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1659 shrink(shrink_bytes);
1660 }
1661 }
1662
1663
1664 HeapWord*
1665 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1666 bool* succeeded) {
1667 assert_at_safepoint(true /* should_be_vm_thread */);
1668
1669 *succeeded = true;
1670 // Let's attempt the allocation first.
1671 HeapWord* result =
1672 attempt_allocation_at_safepoint(word_size,
1673 false /* expect_null_mutator_alloc_region */);
1674 if (result != NULL) {
1675 assert(*succeeded, "sanity");
1676 return result;
1677 }
1678
1679 // In a G1 heap, we're supposed to keep allocation from failing by
1680 // incremental pauses. Therefore, at least for now, we'll favor
1681 // expansion over collection. (This might change in the future if we can
1682 // do something smarter than full collection to satisfy a failed alloc.)
1683 result = expand_and_allocate(word_size);
1684 if (result != NULL) {
1685 assert(*succeeded, "sanity");
1686 return result;
1687 }
1688
1689 // Expansion didn't work, we'll try to do a Full GC.
1690 bool gc_succeeded = do_collection(false, /* explicit_gc */
1691 false, /* clear_all_soft_refs */
1692 word_size);
1693 if (!gc_succeeded) {
1694 *succeeded = false;
1695 return NULL;
1696 }
1697
1698 // Retry the allocation
1699 result = attempt_allocation_at_safepoint(word_size,
1700 true /* expect_null_mutator_alloc_region */);
1701 if (result != NULL) {
1702 assert(*succeeded, "sanity");
1703 return result;
1704 }
1705
1706 // Then, try a Full GC that will collect all soft references.
1707 gc_succeeded = do_collection(false, /* explicit_gc */
1708 true, /* clear_all_soft_refs */
1709 word_size);
1710 if (!gc_succeeded) {
1711 *succeeded = false;
1712 return NULL;
1713 }
1714
1715 // Retry the allocation once more
1716 result = attempt_allocation_at_safepoint(word_size,
1717 true /* expect_null_mutator_alloc_region */);
1718 if (result != NULL) {
1719 assert(*succeeded, "sanity");
1720 return result;
1721 }
1722
1723 assert(!collector_policy()->should_clear_all_soft_refs(),
1724 "Flag should have been handled and cleared prior to this point");
1725
1726 // What else? We might try synchronous finalization later. If the total
1727 // space available is large enough for the allocation, then a more
1728 // complete compaction phase than we've tried so far might be
1729 // appropriate.
1730 assert(*succeeded, "sanity");
1731 return NULL;
1732 }
1733
1734 // Attempting to expand the heap sufficiently
1735 // to support an allocation of the given "word_size". If
1736 // successful, perform the allocation and return the address of the
1737 // allocated block, or else "NULL".
1738
1739 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1740 assert_at_safepoint(true /* should_be_vm_thread */);
1741
1742 verify_region_sets_optional();
1743
1744 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1745 ergo_verbose1(ErgoHeapSizing,
1746 "attempt heap expansion",
1747 ergo_format_reason("allocation request failed")
1748 ergo_format_byte("allocation request"),
1749 word_size * HeapWordSize);
1750 if (expand(expand_bytes)) {
1751 _hrs.verify_optional();
1752 verify_region_sets_optional();
1753 return attempt_allocation_at_safepoint(word_size,
1754 false /* expect_null_mutator_alloc_region */);
1755 }
1756 return NULL;
1757 }
1758
1759 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1760 HeapWord* new_end) {
1761 assert(old_end != new_end, "don't call this otherwise");
1762 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1763
1764 // Update the committed mem region.
1765 _g1_committed.set_end(new_end);
1766 // Tell the card table about the update.
1767 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1768 // Tell the BOT about the update.
1769 _bot_shared->resize(_g1_committed.word_size());
1770 // Tell the hot card cache about the update
1771 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1772 }
1773
1774 bool G1CollectedHeap::expand(size_t expand_bytes) {
1775 size_t old_mem_size = _g1_storage.committed_size();
1776 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1777 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1778 HeapRegion::GrainBytes);
1779 ergo_verbose2(ErgoHeapSizing,
1780 "expand the heap",
1781 ergo_format_byte("requested expansion amount")
1782 ergo_format_byte("attempted expansion amount"),
1783 expand_bytes, aligned_expand_bytes);
1784
1785 // First commit the memory.
1786 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1787 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1788 if (successful) {
1789 // Then propagate this update to the necessary data structures.
1790 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1791 update_committed_space(old_end, new_end);
1792
1793 FreeRegionList expansion_list("Local Expansion List");
1794 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1795 assert(mr.start() == old_end, "post-condition");
1796 // mr might be a smaller region than what was requested if
1797 // expand_by() was unable to allocate the HeapRegion instances
1798 assert(mr.end() <= new_end, "post-condition");
1799
1800 size_t actual_expand_bytes = mr.byte_size();
1801 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1802 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1803 "post-condition");
1804 if (actual_expand_bytes < aligned_expand_bytes) {
1805 // We could not expand _hrs to the desired size. In this case we
1806 // need to shrink the committed space accordingly.
1807 assert(mr.end() < new_end, "invariant");
1808
1809 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1810 // First uncommit the memory.
1811 _g1_storage.shrink_by(diff_bytes);
1812 // Then propagate this update to the necessary data structures.
1813 update_committed_space(new_end, mr.end());
1814 }
1815 _free_list.add_as_tail(&expansion_list);
1816
1817 if (_hr_printer.is_active()) {
1818 HeapWord* curr = mr.start();
1819 while (curr < mr.end()) {
1820 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1821 _hr_printer.commit(curr, curr_end);
1822 curr = curr_end;
1823 }
1824 assert(curr == mr.end(), "post-condition");
1825 }
1826 g1_policy()->record_new_heap_size(n_regions());
1827 } else {
1828 ergo_verbose0(ErgoHeapSizing,
1829 "did not expand the heap",
1830 ergo_format_reason("heap expansion operation failed"));
1831 // The expansion of the virtual storage space was unsuccessful.
1832 // Let's see if it was because we ran out of swap.
1833 if (G1ExitOnExpansionFailure &&
1834 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1835 // We had head room...
1836 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1837 }
1838 }
1839 return successful;
1840 }
1841
1842 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1843 size_t old_mem_size = _g1_storage.committed_size();
1844 size_t aligned_shrink_bytes =
1845 ReservedSpace::page_align_size_down(shrink_bytes);
1846 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1847 HeapRegion::GrainBytes);
1848 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1849
1850 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1851 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1852 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1853
1854 ergo_verbose3(ErgoHeapSizing,
1855 "shrink the heap",
1856 ergo_format_byte("requested shrinking amount")
1857 ergo_format_byte("aligned shrinking amount")
1858 ergo_format_byte("attempted shrinking amount"),
1859 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1860 if (num_regions_removed > 0) {
1861 _g1_storage.shrink_by(shrunk_bytes);
1862 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1863
1864 if (_hr_printer.is_active()) {
1865 HeapWord* curr = old_end;
1866 while (curr > new_end) {
1867 HeapWord* curr_end = curr;
1868 curr -= HeapRegion::GrainWords;
1869 _hr_printer.uncommit(curr, curr_end);
1870 }
1871 }
1872
1873 _expansion_regions += num_regions_removed;
1874 update_committed_space(old_end, new_end);
1875 HeapRegionRemSet::shrink_heap(n_regions());
1876 g1_policy()->record_new_heap_size(n_regions());
1877 } else {
1878 ergo_verbose0(ErgoHeapSizing,
1879 "did not shrink the heap",
1880 ergo_format_reason("heap shrinking operation failed"));
1881 }
1882 }
1883
1884 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1885 verify_region_sets_optional();
1886
1887 // We should only reach here at the end of a Full GC which means we
1888 // should not not be holding to any GC alloc regions. The method
1889 // below will make sure of that and do any remaining clean up.
1890 abandon_gc_alloc_regions();
1891
1892 // Instead of tearing down / rebuilding the free lists here, we
1893 // could instead use the remove_all_pending() method on free_list to
1894 // remove only the ones that we need to remove.
1895 tear_down_region_sets(true /* free_list_only */);
1896 shrink_helper(shrink_bytes);
1897 rebuild_region_sets(true /* free_list_only */);
1898
1899 _hrs.verify_optional();
1900 verify_region_sets_optional();
1901 }
1902
1903 // Public methods.
1904
1905 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1906 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1907 #endif // _MSC_VER
1908
1909
1910 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1911 SharedHeap(policy_),
1912 _g1_policy(policy_),
1913 _dirty_card_queue_set(false),
1914 _into_cset_dirty_card_queue_set(false),
1915 _is_alive_closure_cm(this),
1916 _is_alive_closure_stw(this),
1917 _ref_processor_cm(NULL),
1918 _ref_processor_stw(NULL),
1919 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1920 _bot_shared(NULL),
1921 _evac_failure_scan_stack(NULL),
1922 _mark_in_progress(false),
1923 _cg1r(NULL), _summary_bytes_used(0),
1924 _g1mm(NULL),
1925 _refine_cte_cl(NULL),
1926 _full_collection(false),
1927 _free_list("Master Free List"),
1928 _secondary_free_list("Secondary Free List"),
1929 _old_set("Old Set"),
1930 _humongous_set("Master Humongous Set"),
1931 _free_regions_coming(false),
1932 _young_list(new YoungList(this)),
1933 _gc_time_stamp(0),
1934 _retained_old_gc_alloc_region(NULL),
1935 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1936 _old_plab_stats(OldPLABSize, PLABWeight),
1937 _expand_heap_after_alloc_failure(true),
1938 _surviving_young_words(NULL),
1939 _old_marking_cycles_started(0),
1940 _old_marking_cycles_completed(0),
1941 _concurrent_cycle_started(false),
1942 _in_cset_fast_test(NULL),
1943 _in_cset_fast_test_base(NULL),
1944 _dirty_cards_region_list(NULL),
1945 _worker_cset_start_region(NULL),
1946 _worker_cset_start_region_time_stamp(NULL),
1947 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1948 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1949 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1950 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1951
1952 _g1h = this;
1953 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1954 vm_exit_during_initialization("Failed necessary allocation.");
1955 }
1956
1957 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1958
1959 int n_queues = MAX2((int)ParallelGCThreads, 1);
1960 _task_queues = new RefToScanQueueSet(n_queues);
1961
1962 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1963 assert(n_rem_sets > 0, "Invariant.");
1964
1965 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1966 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1967 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1968
1969 for (int i = 0; i < n_queues; i++) {
1970 RefToScanQueue* q = new RefToScanQueue();
1971 q->initialize();
1972 _task_queues->register_queue(i, q);
1973 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1974 }
1975 clear_cset_start_regions();
1976
1977 // Initialize the G1EvacuationFailureALot counters and flags.
1978 NOT_PRODUCT(reset_evacuation_should_fail();)
1979
1980 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1981 }
1982
1983 jint G1CollectedHeap::initialize() {
1984 CollectedHeap::pre_initialize();
1985 os::enable_vtime();
1986
1987 G1Log::init();
1988
1989 // Necessary to satisfy locking discipline assertions.
1990
1991 MutexLocker x(Heap_lock);
1992
1993 // We have to initialize the printer before committing the heap, as
1994 // it will be used then.
1995 _hr_printer.set_active(G1PrintHeapRegions);
1996
1997 // While there are no constraints in the GC code that HeapWordSize
1998 // be any particular value, there are multiple other areas in the
1999 // system which believe this to be true (e.g. oop->object_size in some
2000 // cases incorrectly returns the size in wordSize units rather than
2001 // HeapWordSize).
2002 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2003
2004 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2005 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2006 size_t heap_alignment = collector_policy()->max_alignment();
2007
2008 // Ensure that the sizes are properly aligned.
2009 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2010 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2011 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2012
2013 _cg1r = new ConcurrentG1Refine(this);
2014
2015 // Reserve the maximum.
2016
2017 // When compressed oops are enabled, the preferred heap base
2018 // is calculated by subtracting the requested size from the
2019 // 32Gb boundary and using the result as the base address for
2020 // heap reservation. If the requested size is not aligned to
2021 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2022 // into the ReservedHeapSpace constructor) then the actual
2023 // base of the reserved heap may end up differing from the
2024 // address that was requested (i.e. the preferred heap base).
2025 // If this happens then we could end up using a non-optimal
2026 // compressed oops mode.
2027
2028 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2029 heap_alignment);
2030
2031 // It is important to do this in a way such that concurrent readers can't
2032 // temporarily think something is in the heap. (I've actually seen this
2033 // happen in asserts: DLD.)
2034 _reserved.set_word_size(0);
2035 _reserved.set_start((HeapWord*)heap_rs.base());
2036 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2037
2038 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2039
2040 // Create the gen rem set (and barrier set) for the entire reserved region.
2041 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2042 set_barrier_set(rem_set()->bs());
2043 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2044 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2045 return JNI_ENOMEM;
2046 }
2047
2048 // Also create a G1 rem set.
2049 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2050
2051 // Carve out the G1 part of the heap.
2052
2053 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2054 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2055 g1_rs.size()/HeapWordSize);
2056
2057 _g1_storage.initialize(g1_rs, 0);
2058 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2059 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2060 (HeapWord*) _g1_reserved.end());
2061 assert(_hrs.max_length() == _expansion_regions,
2062 err_msg("max length: %u expansion regions: %u",
2063 _hrs.max_length(), _expansion_regions));
2064
2065 // Do later initialization work for concurrent refinement.
2066 _cg1r->init();
2067
2068 // 6843694 - ensure that the maximum region index can fit
2069 // in the remembered set structures.
2070 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2071 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2072
2073 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2074 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2075 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2076 "too many cards per region");
2077
2078 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2079
2080 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2081 heap_word_size(init_byte_size));
2082
2083 _g1h = this;
2084
2085 _in_cset_fast_test_length = max_regions();
2086 _in_cset_fast_test_base =
2087 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2088
2089 // We're biasing _in_cset_fast_test to avoid subtracting the
2090 // beginning of the heap every time we want to index; basically
2091 // it's the same with what we do with the card table.
2092 _in_cset_fast_test = _in_cset_fast_test_base -
2093 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2094
2095 // Clear the _cset_fast_test bitmap in anticipation of adding
2096 // regions to the incremental collection set for the first
2097 // evacuation pause.
2098 clear_cset_fast_test();
2099
2100 // Create the ConcurrentMark data structure and thread.
2101 // (Must do this late, so that "max_regions" is defined.)
2102 _cm = new ConcurrentMark(this, heap_rs);
2103 if (_cm == NULL || !_cm->completed_initialization()) {
2104 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2105 return JNI_ENOMEM;
2106 }
2107 _cmThread = _cm->cmThread();
2108
2109 // Initialize the from_card cache structure of HeapRegionRemSet.
2110 HeapRegionRemSet::init_heap(max_regions());
2111
2112 // Now expand into the initial heap size.
2113 if (!expand(init_byte_size)) {
2114 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2115 return JNI_ENOMEM;
2116 }
2117
2118 // Perform any initialization actions delegated to the policy.
2119 g1_policy()->init();
2120
2121 _refine_cte_cl =
2122 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2123 g1_rem_set(),
2124 concurrent_g1_refine());
2125 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2126
2127 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2128 SATB_Q_FL_lock,
2129 G1SATBProcessCompletedThreshold,
2130 Shared_SATB_Q_lock);
2131
2132 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2133 DirtyCardQ_FL_lock,
2134 concurrent_g1_refine()->yellow_zone(),
2135 concurrent_g1_refine()->red_zone(),
2136 Shared_DirtyCardQ_lock);
2137
2138 if (G1DeferredRSUpdate) {
2139 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2140 DirtyCardQ_FL_lock,
2141 -1, // never trigger processing
2142 -1, // no limit on length
2143 Shared_DirtyCardQ_lock,
2144 &JavaThread::dirty_card_queue_set());
2145 }
2146
2147 // Initialize the card queue set used to hold cards containing
2148 // references into the collection set.
2149 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2150 DirtyCardQ_FL_lock,
2151 -1, // never trigger processing
2152 -1, // no limit on length
2153 Shared_DirtyCardQ_lock,
2154 &JavaThread::dirty_card_queue_set());
2155
2156 // In case we're keeping closure specialization stats, initialize those
2157 // counts and that mechanism.
2158 SpecializationStats::clear();
2159
2160 // Here we allocate the dummy full region that is required by the
2161 // G1AllocRegion class. If we don't pass an address in the reserved
2162 // space here, lots of asserts fire.
2163
2164 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2165 _g1_reserved.start());
2166 // We'll re-use the same region whether the alloc region will
2167 // require BOT updates or not and, if it doesn't, then a non-young
2168 // region will complain that it cannot support allocations without
2169 // BOT updates. So we'll tag the dummy region as young to avoid that.
2170 dummy_region->set_young();
2171 // Make sure it's full.
2172 dummy_region->set_top(dummy_region->end());
2173 G1AllocRegion::setup(this, dummy_region);
2174
2175 init_mutator_alloc_region();
2176
2177 // Do create of the monitoring and management support so that
2178 // values in the heap have been properly initialized.
2179 _g1mm = new G1MonitoringSupport(this);
2180
2181 return JNI_OK;
2182 }
2183
2184 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2185 return HeapRegion::max_region_size();
2186 }
2187
2188 void G1CollectedHeap::ref_processing_init() {
2189 // Reference processing in G1 currently works as follows:
2190 //
2191 // * There are two reference processor instances. One is
2192 // used to record and process discovered references
2193 // during concurrent marking; the other is used to
2194 // record and process references during STW pauses
2195 // (both full and incremental).
2196 // * Both ref processors need to 'span' the entire heap as
2197 // the regions in the collection set may be dotted around.
2198 //
2199 // * For the concurrent marking ref processor:
2200 // * Reference discovery is enabled at initial marking.
2201 // * Reference discovery is disabled and the discovered
2202 // references processed etc during remarking.
2203 // * Reference discovery is MT (see below).
2204 // * Reference discovery requires a barrier (see below).
2205 // * Reference processing may or may not be MT
2206 // (depending on the value of ParallelRefProcEnabled
2207 // and ParallelGCThreads).
2208 // * A full GC disables reference discovery by the CM
2209 // ref processor and abandons any entries on it's
2210 // discovered lists.
2211 //
2212 // * For the STW processor:
2213 // * Non MT discovery is enabled at the start of a full GC.
2214 // * Processing and enqueueing during a full GC is non-MT.
2215 // * During a full GC, references are processed after marking.
2216 //
2217 // * Discovery (may or may not be MT) is enabled at the start
2218 // of an incremental evacuation pause.
2219 // * References are processed near the end of a STW evacuation pause.
2220 // * For both types of GC:
2221 // * Discovery is atomic - i.e. not concurrent.
2222 // * Reference discovery will not need a barrier.
2223
2224 SharedHeap::ref_processing_init();
2225 MemRegion mr = reserved_region();
2226
2227 // Concurrent Mark ref processor
2228 _ref_processor_cm =
2229 new ReferenceProcessor(mr, // span
2230 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2231 // mt processing
2232 (int) ParallelGCThreads,
2233 // degree of mt processing
2234 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2235 // mt discovery
2236 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2237 // degree of mt discovery
2238 false,
2239 // Reference discovery is not atomic
2240 &_is_alive_closure_cm,
2241 // is alive closure
2242 // (for efficiency/performance)
2243 true);
2244 // Setting next fields of discovered
2245 // lists requires a barrier.
2246
2247 // STW ref processor
2248 _ref_processor_stw =
2249 new ReferenceProcessor(mr, // span
2250 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2251 // mt processing
2252 MAX2((int)ParallelGCThreads, 1),
2253 // degree of mt processing
2254 (ParallelGCThreads > 1),
2255 // mt discovery
2256 MAX2((int)ParallelGCThreads, 1),
2257 // degree of mt discovery
2258 true,
2259 // Reference discovery is atomic
2260 &_is_alive_closure_stw,
2261 // is alive closure
2262 // (for efficiency/performance)
2263 false);
2264 // Setting next fields of discovered
2265 // lists requires a barrier.
2266 }
2267
2268 size_t G1CollectedHeap::capacity() const {
2269 return _g1_committed.byte_size();
2270 }
2271
2272 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2273 assert(!hr->continuesHumongous(), "pre-condition");
2274 hr->reset_gc_time_stamp();
2275 if (hr->startsHumongous()) {
2276 uint first_index = hr->hrs_index() + 1;
2277 uint last_index = hr->last_hc_index();
2278 for (uint i = first_index; i < last_index; i += 1) {
2279 HeapRegion* chr = region_at(i);
2280 assert(chr->continuesHumongous(), "sanity");
2281 chr->reset_gc_time_stamp();
2282 }
2283 }
2284 }
2285
2286 #ifndef PRODUCT
2287 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2288 private:
2289 unsigned _gc_time_stamp;
2290 bool _failures;
2291
2292 public:
2293 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2294 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2295
2296 virtual bool doHeapRegion(HeapRegion* hr) {
2297 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2298 if (_gc_time_stamp != region_gc_time_stamp) {
2299 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2300 "expected %d", HR_FORMAT_PARAMS(hr),
2301 region_gc_time_stamp, _gc_time_stamp);
2302 _failures = true;
2303 }
2304 return false;
2305 }
2306
2307 bool failures() { return _failures; }
2308 };
2309
2310 void G1CollectedHeap::check_gc_time_stamps() {
2311 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2312 heap_region_iterate(&cl);
2313 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2314 }
2315 #endif // PRODUCT
2316
2317 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2318 DirtyCardQueue* into_cset_dcq,
2319 bool concurrent,
2320 int worker_i) {
2321 // Clean cards in the hot card cache
2322 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2323 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2324
2325 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2326 int n_completed_buffers = 0;
2327 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2328 n_completed_buffers++;
2329 }
2330 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2331 dcqs.clear_n_completed_buffers();
2332 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2333 }
2334
2335
2336 // Computes the sum of the storage used by the various regions.
2337
2338 size_t G1CollectedHeap::used() const {
2339 assert(Heap_lock->owner() != NULL,
2340 "Should be owned on this thread's behalf.");
2341 size_t result = _summary_bytes_used;
2342 // Read only once in case it is set to NULL concurrently
2343 HeapRegion* hr = _mutator_alloc_region.get();
2344 if (hr != NULL)
2345 result += hr->used();
2346 return result;
2347 }
2348
2349 size_t G1CollectedHeap::used_unlocked() const {
2350 size_t result = _summary_bytes_used;
2351 return result;
2352 }
2353
2354 class SumUsedClosure: public HeapRegionClosure {
2355 size_t _used;
2356 public:
2357 SumUsedClosure() : _used(0) {}
2358 bool doHeapRegion(HeapRegion* r) {
2359 if (!r->continuesHumongous()) {
2360 _used += r->used();
2361 }
2362 return false;
2363 }
2364 size_t result() { return _used; }
2365 };
2366
2367 size_t G1CollectedHeap::recalculate_used() const {
2368 SumUsedClosure blk;
2369 heap_region_iterate(&blk);
2370 return blk.result();
2371 }
2372
2373 size_t G1CollectedHeap::unsafe_max_alloc() {
2374 if (free_regions() > 0) return HeapRegion::GrainBytes;
2375 // otherwise, is there space in the current allocation region?
2376
2377 // We need to store the current allocation region in a local variable
2378 // here. The problem is that this method doesn't take any locks and
2379 // there may be other threads which overwrite the current allocation
2380 // region field. attempt_allocation(), for example, sets it to NULL
2381 // and this can happen *after* the NULL check here but before the call
2382 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2383 // to be a problem in the optimized build, since the two loads of the
2384 // current allocation region field are optimized away.
2385 HeapRegion* hr = _mutator_alloc_region.get();
2386 if (hr == NULL) {
2387 return 0;
2388 }
2389 return hr->free();
2390 }
2391
2392 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2393 switch (cause) {
2394 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2395 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2396 case GCCause::_g1_humongous_allocation: return true;
2397 default: return false;
2398 }
2399 }
2400
2401 #ifndef PRODUCT
2402 void G1CollectedHeap::allocate_dummy_regions() {
2403 // Let's fill up most of the region
2404 size_t word_size = HeapRegion::GrainWords - 1024;
2405 // And as a result the region we'll allocate will be humongous.
2406 guarantee(isHumongous(word_size), "sanity");
2407
2408 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2409 // Let's use the existing mechanism for the allocation
2410 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2411 if (dummy_obj != NULL) {
2412 MemRegion mr(dummy_obj, word_size);
2413 CollectedHeap::fill_with_object(mr);
2414 } else {
2415 // If we can't allocate once, we probably cannot allocate
2416 // again. Let's get out of the loop.
2417 break;
2418 }
2419 }
2420 }
2421 #endif // !PRODUCT
2422
2423 void G1CollectedHeap::increment_old_marking_cycles_started() {
2424 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2425 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2426 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2427 _old_marking_cycles_started, _old_marking_cycles_completed));
2428
2429 _old_marking_cycles_started++;
2430 }
2431
2432 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2433 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2434
2435 // We assume that if concurrent == true, then the caller is a
2436 // concurrent thread that was joined the Suspendible Thread
2437 // Set. If there's ever a cheap way to check this, we should add an
2438 // assert here.
2439
2440 // Given that this method is called at the end of a Full GC or of a
2441 // concurrent cycle, and those can be nested (i.e., a Full GC can
2442 // interrupt a concurrent cycle), the number of full collections
2443 // completed should be either one (in the case where there was no
2444 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2445 // behind the number of full collections started.
2446
2447 // This is the case for the inner caller, i.e. a Full GC.
2448 assert(concurrent ||
2449 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2450 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2451 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2452 "is inconsistent with _old_marking_cycles_completed = %u",
2453 _old_marking_cycles_started, _old_marking_cycles_completed));
2454
2455 // This is the case for the outer caller, i.e. the concurrent cycle.
2456 assert(!concurrent ||
2457 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2458 err_msg("for outer caller (concurrent cycle): "
2459 "_old_marking_cycles_started = %u "
2460 "is inconsistent with _old_marking_cycles_completed = %u",
2461 _old_marking_cycles_started, _old_marking_cycles_completed));
2462
2463 _old_marking_cycles_completed += 1;
2464
2465 // We need to clear the "in_progress" flag in the CM thread before
2466 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2467 // is set) so that if a waiter requests another System.gc() it doesn't
2468 // incorrectly see that a marking cycle is still in progress.
2469 if (concurrent) {
2470 _cmThread->clear_in_progress();
2471 }
2472
2473 // This notify_all() will ensure that a thread that called
2474 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2475 // and it's waiting for a full GC to finish will be woken up. It is
2476 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2477 FullGCCount_lock->notify_all();
2478 }
2479
2480 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2481 _concurrent_cycle_started = true;
2482 _gc_timer_cm->register_gc_start(start_time);
2483
2484 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2485 trace_heap_before_gc(_gc_tracer_cm);
2486 }
2487
2488 void G1CollectedHeap::register_concurrent_cycle_end() {
2489 if (_concurrent_cycle_started) {
2490 if (_cm->has_aborted()) {
2491 _gc_tracer_cm->report_concurrent_mode_failure();
2492 }
2493
2494 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2495 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2496
2497 _concurrent_cycle_started = false;
2498 }
2499 }
2500
2501 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2502 if (_concurrent_cycle_started) {
2503 trace_heap_after_gc(_gc_tracer_cm);
2504 }
2505 }
2506
2507 G1YCType G1CollectedHeap::yc_type() {
2508 bool is_young = g1_policy()->gcs_are_young();
2509 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2510 bool is_during_mark = mark_in_progress();
2511
2512 if (is_initial_mark) {
2513 return InitialMark;
2514 } else if (is_during_mark) {
2515 return DuringMark;
2516 } else if (is_young) {
2517 return Normal;
2518 } else {
2519 return Mixed;
2520 }
2521 }
2522
2523 void G1CollectedHeap::collect(GCCause::Cause cause) {
2524 assert_heap_not_locked();
2525
2526 unsigned int gc_count_before;
2527 unsigned int old_marking_count_before;
2528 bool retry_gc;
2529
2530 do {
2531 retry_gc = false;
2532
2533 {
2534 MutexLocker ml(Heap_lock);
2535
2536 // Read the GC count while holding the Heap_lock
2537 gc_count_before = total_collections();
2538 old_marking_count_before = _old_marking_cycles_started;
2539 }
2540
2541 if (should_do_concurrent_full_gc(cause)) {
2542 // Schedule an initial-mark evacuation pause that will start a
2543 // concurrent cycle. We're setting word_size to 0 which means that
2544 // we are not requesting a post-GC allocation.
2545 VM_G1IncCollectionPause op(gc_count_before,
2546 0, /* word_size */
2547 true, /* should_initiate_conc_mark */
2548 g1_policy()->max_pause_time_ms(),
2549 cause);
2550
2551 VMThread::execute(&op);
2552 if (!op.pause_succeeded()) {
2553 if (old_marking_count_before == _old_marking_cycles_started) {
2554 retry_gc = op.should_retry_gc();
2555 } else {
2556 // A Full GC happened while we were trying to schedule the
2557 // initial-mark GC. No point in starting a new cycle given
2558 // that the whole heap was collected anyway.
2559 }
2560
2561 if (retry_gc) {
2562 if (GC_locker::is_active_and_needs_gc()) {
2563 GC_locker::stall_until_clear();
2564 }
2565 }
2566 }
2567 } else {
2568 if (cause == GCCause::_gc_locker
2569 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2570
2571 // Schedule a standard evacuation pause. We're setting word_size
2572 // to 0 which means that we are not requesting a post-GC allocation.
2573 VM_G1IncCollectionPause op(gc_count_before,
2574 0, /* word_size */
2575 false, /* should_initiate_conc_mark */
2576 g1_policy()->max_pause_time_ms(),
2577 cause);
2578 VMThread::execute(&op);
2579 } else {
2580 // Schedule a Full GC.
2581 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2582 VMThread::execute(&op);
2583 }
2584 }
2585 } while (retry_gc);
2586 }
2587
2588 bool G1CollectedHeap::is_in(const void* p) const {
2589 if (_g1_committed.contains(p)) {
2590 // Given that we know that p is in the committed space,
2591 // heap_region_containing_raw() should successfully
2592 // return the containing region.
2593 HeapRegion* hr = heap_region_containing_raw(p);
2594 return hr->is_in(p);
2595 } else {
2596 return false;
2597 }
2598 }
2599
2600 // Iteration functions.
2601
2602 // Iterates an OopClosure over all ref-containing fields of objects
2603 // within a HeapRegion.
2604
2605 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2606 MemRegion _mr;
2607 ExtendedOopClosure* _cl;
2608 public:
2609 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2610 : _mr(mr), _cl(cl) {}
2611 bool doHeapRegion(HeapRegion* r) {
2612 if (!r->continuesHumongous()) {
2613 r->oop_iterate(_cl);
2614 }
2615 return false;
2616 }
2617 };
2618
2619 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2620 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2621 heap_region_iterate(&blk);
2622 }
2623
2624 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2625 IterateOopClosureRegionClosure blk(mr, cl);
2626 heap_region_iterate(&blk);
2627 }
2628
2629 // Iterates an ObjectClosure over all objects within a HeapRegion.
2630
2631 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2632 ObjectClosure* _cl;
2633 public:
2634 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2635 bool doHeapRegion(HeapRegion* r) {
2636 if (! r->continuesHumongous()) {
2637 r->object_iterate(_cl);
2638 }
2639 return false;
2640 }
2641 };
2642
2643 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2644 IterateObjectClosureRegionClosure blk(cl);
2645 heap_region_iterate(&blk);
2646 }
2647
2648 // Calls a SpaceClosure on a HeapRegion.
2649
2650 class SpaceClosureRegionClosure: public HeapRegionClosure {
2651 SpaceClosure* _cl;
2652 public:
2653 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2654 bool doHeapRegion(HeapRegion* r) {
2655 _cl->do_space(r);
2656 return false;
2657 }
2658 };
2659
2660 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2661 SpaceClosureRegionClosure blk(cl);
2662 heap_region_iterate(&blk);
2663 }
2664
2665 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2666 _hrs.iterate(cl);
2667 }
2668
2669 void
2670 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2671 uint worker_id,
2672 uint no_of_par_workers,
2673 jint claim_value) {
2674 const uint regions = n_regions();
2675 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2676 no_of_par_workers :
2677 1);
2678 assert(UseDynamicNumberOfGCThreads ||
2679 no_of_par_workers == workers()->total_workers(),
2680 "Non dynamic should use fixed number of workers");
2681 // try to spread out the starting points of the workers
2682 const HeapRegion* start_hr =
2683 start_region_for_worker(worker_id, no_of_par_workers);
2684 const uint start_index = start_hr->hrs_index();
2685
2686 // each worker will actually look at all regions
2687 for (uint count = 0; count < regions; ++count) {
2688 const uint index = (start_index + count) % regions;
2689 assert(0 <= index && index < regions, "sanity");
2690 HeapRegion* r = region_at(index);
2691 // we'll ignore "continues humongous" regions (we'll process them
2692 // when we come across their corresponding "start humongous"
2693 // region) and regions already claimed
2694 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2695 continue;
2696 }
2697 // OK, try to claim it
2698 if (r->claimHeapRegion(claim_value)) {
2699 // success!
2700 assert(!r->continuesHumongous(), "sanity");
2701 if (r->startsHumongous()) {
2702 // If the region is "starts humongous" we'll iterate over its
2703 // "continues humongous" first; in fact we'll do them
2704 // first. The order is important. In on case, calling the
2705 // closure on the "starts humongous" region might de-allocate
2706 // and clear all its "continues humongous" regions and, as a
2707 // result, we might end up processing them twice. So, we'll do
2708 // them first (notice: most closures will ignore them anyway) and
2709 // then we'll do the "starts humongous" region.
2710 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2711 HeapRegion* chr = region_at(ch_index);
2712
2713 // if the region has already been claimed or it's not
2714 // "continues humongous" we're done
2715 if (chr->claim_value() == claim_value ||
2716 !chr->continuesHumongous()) {
2717 break;
2718 }
2719
2720 // No one should have claimed it directly. We can given
2721 // that we claimed its "starts humongous" region.
2722 assert(chr->claim_value() != claim_value, "sanity");
2723 assert(chr->humongous_start_region() == r, "sanity");
2724
2725 if (chr->claimHeapRegion(claim_value)) {
2726 // we should always be able to claim it; no one else should
2727 // be trying to claim this region
2728
2729 bool res2 = cl->doHeapRegion(chr);
2730 assert(!res2, "Should not abort");
2731
2732 // Right now, this holds (i.e., no closure that actually
2733 // does something with "continues humongous" regions
2734 // clears them). We might have to weaken it in the future,
2735 // but let's leave these two asserts here for extra safety.
2736 assert(chr->continuesHumongous(), "should still be the case");
2737 assert(chr->humongous_start_region() == r, "sanity");
2738 } else {
2739 guarantee(false, "we should not reach here");
2740 }
2741 }
2742 }
2743
2744 assert(!r->continuesHumongous(), "sanity");
2745 bool res = cl->doHeapRegion(r);
2746 assert(!res, "Should not abort");
2747 }
2748 }
2749 }
2750
2751 class ResetClaimValuesClosure: public HeapRegionClosure {
2752 public:
2753 bool doHeapRegion(HeapRegion* r) {
2754 r->set_claim_value(HeapRegion::InitialClaimValue);
2755 return false;
2756 }
2757 };
2758
2759 void G1CollectedHeap::reset_heap_region_claim_values() {
2760 ResetClaimValuesClosure blk;
2761 heap_region_iterate(&blk);
2762 }
2763
2764 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2765 ResetClaimValuesClosure blk;
2766 collection_set_iterate(&blk);
2767 }
2768
2769 #ifdef ASSERT
2770 // This checks whether all regions in the heap have the correct claim
2771 // value. I also piggy-backed on this a check to ensure that the
2772 // humongous_start_region() information on "continues humongous"
2773 // regions is correct.
2774
2775 class CheckClaimValuesClosure : public HeapRegionClosure {
2776 private:
2777 jint _claim_value;
2778 uint _failures;
2779 HeapRegion* _sh_region;
2780
2781 public:
2782 CheckClaimValuesClosure(jint claim_value) :
2783 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2784 bool doHeapRegion(HeapRegion* r) {
2785 if (r->claim_value() != _claim_value) {
2786 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2787 "claim value = %d, should be %d",
2788 HR_FORMAT_PARAMS(r),
2789 r->claim_value(), _claim_value);
2790 ++_failures;
2791 }
2792 if (!r->isHumongous()) {
2793 _sh_region = NULL;
2794 } else if (r->startsHumongous()) {
2795 _sh_region = r;
2796 } else if (r->continuesHumongous()) {
2797 if (r->humongous_start_region() != _sh_region) {
2798 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2799 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2800 HR_FORMAT_PARAMS(r),
2801 r->humongous_start_region(),
2802 _sh_region);
2803 ++_failures;
2804 }
2805 }
2806 return false;
2807 }
2808 uint failures() { return _failures; }
2809 };
2810
2811 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2812 CheckClaimValuesClosure cl(claim_value);
2813 heap_region_iterate(&cl);
2814 return cl.failures() == 0;
2815 }
2816
2817 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2818 private:
2819 jint _claim_value;
2820 uint _failures;
2821
2822 public:
2823 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2824 _claim_value(claim_value), _failures(0) { }
2825
2826 uint failures() { return _failures; }
2827
2828 bool doHeapRegion(HeapRegion* hr) {
2829 assert(hr->in_collection_set(), "how?");
2830 assert(!hr->isHumongous(), "H-region in CSet");
2831 if (hr->claim_value() != _claim_value) {
2832 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2833 "claim value = %d, should be %d",
2834 HR_FORMAT_PARAMS(hr),
2835 hr->claim_value(), _claim_value);
2836 _failures += 1;
2837 }
2838 return false;
2839 }
2840 };
2841
2842 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2843 CheckClaimValuesInCSetHRClosure cl(claim_value);
2844 collection_set_iterate(&cl);
2845 return cl.failures() == 0;
2846 }
2847 #endif // ASSERT
2848
2849 // Clear the cached CSet starting regions and (more importantly)
2850 // the time stamps. Called when we reset the GC time stamp.
2851 void G1CollectedHeap::clear_cset_start_regions() {
2852 assert(_worker_cset_start_region != NULL, "sanity");
2853 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2854
2855 int n_queues = MAX2((int)ParallelGCThreads, 1);
2856 for (int i = 0; i < n_queues; i++) {
2857 _worker_cset_start_region[i] = NULL;
2858 _worker_cset_start_region_time_stamp[i] = 0;
2859 }
2860 }
2861
2862 // Given the id of a worker, obtain or calculate a suitable
2863 // starting region for iterating over the current collection set.
2864 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2865 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2866
2867 HeapRegion* result = NULL;
2868 unsigned gc_time_stamp = get_gc_time_stamp();
2869
2870 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2871 // Cached starting region for current worker was set
2872 // during the current pause - so it's valid.
2873 // Note: the cached starting heap region may be NULL
2874 // (when the collection set is empty).
2875 result = _worker_cset_start_region[worker_i];
2876 assert(result == NULL || result->in_collection_set(), "sanity");
2877 return result;
2878 }
2879
2880 // The cached entry was not valid so let's calculate
2881 // a suitable starting heap region for this worker.
2882
2883 // We want the parallel threads to start their collection
2884 // set iteration at different collection set regions to
2885 // avoid contention.
2886 // If we have:
2887 // n collection set regions
2888 // p threads
2889 // Then thread t will start at region floor ((t * n) / p)
2890
2891 result = g1_policy()->collection_set();
2892 if (G1CollectedHeap::use_parallel_gc_threads()) {
2893 uint cs_size = g1_policy()->cset_region_length();
2894 uint active_workers = workers()->active_workers();
2895 assert(UseDynamicNumberOfGCThreads ||
2896 active_workers == workers()->total_workers(),
2897 "Unless dynamic should use total workers");
2898
2899 uint end_ind = (cs_size * worker_i) / active_workers;
2900 uint start_ind = 0;
2901
2902 if (worker_i > 0 &&
2903 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2904 // Previous workers starting region is valid
2905 // so let's iterate from there
2906 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2907 result = _worker_cset_start_region[worker_i - 1];
2908 }
2909
2910 for (uint i = start_ind; i < end_ind; i++) {
2911 result = result->next_in_collection_set();
2912 }
2913 }
2914
2915 // Note: the calculated starting heap region may be NULL
2916 // (when the collection set is empty).
2917 assert(result == NULL || result->in_collection_set(), "sanity");
2918 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2919 "should be updated only once per pause");
2920 _worker_cset_start_region[worker_i] = result;
2921 OrderAccess::storestore();
2922 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2923 return result;
2924 }
2925
2926 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2927 uint no_of_par_workers) {
2928 uint worker_num =
2929 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2930 assert(UseDynamicNumberOfGCThreads ||
2931 no_of_par_workers == workers()->total_workers(),
2932 "Non dynamic should use fixed number of workers");
2933 const uint start_index = n_regions() * worker_i / worker_num;
2934 return region_at(start_index);
2935 }
2936
2937 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2938 HeapRegion* r = g1_policy()->collection_set();
2939 while (r != NULL) {
2940 HeapRegion* next = r->next_in_collection_set();
2941 if (cl->doHeapRegion(r)) {
2942 cl->incomplete();
2943 return;
2944 }
2945 r = next;
2946 }
2947 }
2948
2949 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2950 HeapRegionClosure *cl) {
2951 if (r == NULL) {
2952 // The CSet is empty so there's nothing to do.
2953 return;
2954 }
2955
2956 assert(r->in_collection_set(),
2957 "Start region must be a member of the collection set.");
2958 HeapRegion* cur = r;
2959 while (cur != NULL) {
2960 HeapRegion* next = cur->next_in_collection_set();
2961 if (cl->doHeapRegion(cur) && false) {
2962 cl->incomplete();
2963 return;
2964 }
2965 cur = next;
2966 }
2967 cur = g1_policy()->collection_set();
2968 while (cur != r) {
2969 HeapRegion* next = cur->next_in_collection_set();
2970 if (cl->doHeapRegion(cur) && false) {
2971 cl->incomplete();
2972 return;
2973 }
2974 cur = next;
2975 }
2976 }
2977
2978 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2979 return n_regions() > 0 ? region_at(0) : NULL;
2980 }
2981
2982
2983 Space* G1CollectedHeap::space_containing(const void* addr) const {
2984 Space* res = heap_region_containing(addr);
2985 return res;
2986 }
2987
2988 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2989 Space* sp = space_containing(addr);
2990 if (sp != NULL) {
2991 return sp->block_start(addr);
2992 }
2993 return NULL;
2994 }
2995
2996 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2997 Space* sp = space_containing(addr);
2998 assert(sp != NULL, "block_size of address outside of heap");
2999 return sp->block_size(addr);
3000 }
3001
3002 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3003 Space* sp = space_containing(addr);
3004 return sp->block_is_obj(addr);
3005 }
3006
3007 bool G1CollectedHeap::supports_tlab_allocation() const {
3008 return true;
3009 }
3010
3011 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3012 return HeapRegion::GrainBytes;
3013 }
3014
3015 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3016 // Return the remaining space in the cur alloc region, but not less than
3017 // the min TLAB size.
3018
3019 // Also, this value can be at most the humongous object threshold,
3020 // since we can't allow tlabs to grow big enough to accommodate
3021 // humongous objects.
3022
3023 HeapRegion* hr = _mutator_alloc_region.get();
3024 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3025 if (hr == NULL) {
3026 return max_tlab_size;
3027 } else {
3028 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3029 }
3030 }
3031
3032 size_t G1CollectedHeap::max_capacity() const {
3033 return _g1_reserved.byte_size();
3034 }
3035
3036 jlong G1CollectedHeap::millis_since_last_gc() {
3037 // assert(false, "NYI");
3038 return 0;
3039 }
3040
3041 void G1CollectedHeap::prepare_for_verify() {
3042 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3043 ensure_parsability(false);
3044 }
3045 g1_rem_set()->prepare_for_verify();
3046 }
3047
3048 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3049 VerifyOption vo) {
3050 switch (vo) {
3051 case VerifyOption_G1UsePrevMarking:
3052 return hr->obj_allocated_since_prev_marking(obj);
3053 case VerifyOption_G1UseNextMarking:
3054 return hr->obj_allocated_since_next_marking(obj);
3055 case VerifyOption_G1UseMarkWord:
3056 return false;
3057 default:
3058 ShouldNotReachHere();
3059 }
3060 return false; // keep some compilers happy
3061 }
3062
3063 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3064 switch (vo) {
3065 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3066 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3067 case VerifyOption_G1UseMarkWord: return NULL;
3068 default: ShouldNotReachHere();
3069 }
3070 return NULL; // keep some compilers happy
3071 }
3072
3073 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3074 switch (vo) {
3075 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3076 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3077 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3078 default: ShouldNotReachHere();
3079 }
3080 return false; // keep some compilers happy
3081 }
3082
3083 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3084 switch (vo) {
3085 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3086 case VerifyOption_G1UseNextMarking: return "NTAMS";
3087 case VerifyOption_G1UseMarkWord: return "NONE";
3088 default: ShouldNotReachHere();
3089 }
3090 return NULL; // keep some compilers happy
3091 }
3092
3093 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3094 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3095 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3096 // we can change this closure to extend the simpler OopClosure.
3097 class VerifyRootsClosure: public OopsInGenClosure {
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 OopsInGenClosure {
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(os::elapsed_counter());
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(os::elapsed_counter());
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, intptr_t(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, intptr_t(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, intptr_t(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 <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4668 void G1ParCopyClosure<do_gen_barrier, 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 <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4680 void G1ParCopyClosure<do_gen_barrier, 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 <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4704 oop G1ParCopyClosure<do_gen_barrier, 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 <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4801 template <class T>
4802 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4803 ::do_oop_work(T* p) {
4804 oop obj = oopDesc::load_decode_heap_oop(p);
4805 assert(barrier != G1BarrierRS || obj != NULL,
4806 "Precondition: G1BarrierRS implies obj is non-NULL");
4807
4808 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4809
4810 // here the null check is implicit in the cset_fast_test() test
4811 if (_g1->in_cset_fast_test(obj)) {
4812 oop forwardee;
4813 if (obj->is_forwarded()) {
4814 forwardee = obj->forwardee();
4815 } else {
4816 forwardee = copy_to_survivor_space(obj);
4817 }
4818 assert(forwardee != NULL, "forwardee should not be NULL");
4819 oopDesc::encode_store_heap_oop(p, forwardee);
4820 if (do_mark_object && forwardee != obj) {
4821 // If the object is self-forwarded we don't need to explicitly
4822 // mark it, the evacuation failure protocol will do so.
4823 mark_forwarded_object(obj, forwardee);
4824 }
4825
4826 // When scanning the RS, we only care about objs in CS.
4827 if (barrier == G1BarrierRS) {
4828 _par_scan_state->update_rs(_from, p, _worker_id);
4829 } else if (barrier == G1BarrierKlass) {
4830 do_klass_barrier(p, forwardee);
4831 }
4832 } else {
4833 // The object is not in collection set. If we're a root scanning
4834 // closure during an initial mark pause (i.e. do_mark_object will
4835 // be true) then attempt to mark the object.
4836 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4837 mark_object(obj);
4838 }
4839 }
4840
4841 if (barrier == G1BarrierEvac && obj != NULL) {
4842 _par_scan_state->update_rs(_from, p, _worker_id);
4843 }
4844
4845 if (do_gen_barrier && obj != NULL) {
4846 par_do_barrier(p);
4847 }
4848 }
4849
4850 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4851 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4852
4853 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4854 assert(has_partial_array_mask(p), "invariant");
4855 oop from_obj = clear_partial_array_mask(p);
4856
4857 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4858 assert(from_obj->is_objArray(), "must be obj array");
4859 objArrayOop from_obj_array = objArrayOop(from_obj);
4860 // The from-space object contains the real length.
4861 int length = from_obj_array->length();
4862
4863 assert(from_obj->is_forwarded(), "must be forwarded");
4864 oop to_obj = from_obj->forwardee();
4865 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4866 objArrayOop to_obj_array = objArrayOop(to_obj);
4867 // We keep track of the next start index in the length field of the
4868 // to-space object.
4869 int next_index = to_obj_array->length();
4870 assert(0 <= next_index && next_index < length,
4871 err_msg("invariant, next index: %d, length: %d", next_index, length));
4872
4873 int start = next_index;
4874 int end = length;
4875 int remainder = end - start;
4876 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4877 if (remainder > 2 * ParGCArrayScanChunk) {
4878 end = start + ParGCArrayScanChunk;
4879 to_obj_array->set_length(end);
4880 // Push the remainder before we process the range in case another
4881 // worker has run out of things to do and can steal it.
4882 oop* from_obj_p = set_partial_array_mask(from_obj);
4883 _par_scan_state->push_on_queue(from_obj_p);
4884 } else {
4885 assert(length == end, "sanity");
4886 // We'll process the final range for this object. Restore the length
4887 // so that the heap remains parsable in case of evacuation failure.
4888 to_obj_array->set_length(end);
4889 }
4890 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4891 // Process indexes [start,end). It will also process the header
4892 // along with the first chunk (i.e., the chunk with start == 0).
4893 // Note that at this point the length field of to_obj_array is not
4894 // correct given that we are using it to keep track of the next
4895 // start index. oop_iterate_range() (thankfully!) ignores the length
4896 // field and only relies on the start / end parameters. It does
4897 // however return the size of the object which will be incorrect. So
4898 // we have to ignore it even if we wanted to use it.
4899 to_obj_array->oop_iterate_range(&_scanner, start, end);
4900 }
4901
4902 class G1ParEvacuateFollowersClosure : public VoidClosure {
4903 protected:
4904 G1CollectedHeap* _g1h;
4905 G1ParScanThreadState* _par_scan_state;
4906 RefToScanQueueSet* _queues;
4907 ParallelTaskTerminator* _terminator;
4908
4909 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4910 RefToScanQueueSet* queues() { return _queues; }
4911 ParallelTaskTerminator* terminator() { return _terminator; }
4912
4913 public:
4914 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4915 G1ParScanThreadState* par_scan_state,
4916 RefToScanQueueSet* queues,
4917 ParallelTaskTerminator* terminator)
4918 : _g1h(g1h), _par_scan_state(par_scan_state),
4919 _queues(queues), _terminator(terminator) {}
4920
4921 void do_void();
4922
4923 private:
4924 inline bool offer_termination();
4925 };
4926
4927 bool G1ParEvacuateFollowersClosure::offer_termination() {
4928 G1ParScanThreadState* const pss = par_scan_state();
4929 pss->start_term_time();
4930 const bool res = terminator()->offer_termination();
4931 pss->end_term_time();
4932 return res;
4933 }
4934
4935 void G1ParEvacuateFollowersClosure::do_void() {
4936 StarTask stolen_task;
4937 G1ParScanThreadState* const pss = par_scan_state();
4938 pss->trim_queue();
4939
4940 do {
4941 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4942 assert(pss->verify_task(stolen_task), "sanity");
4943 if (stolen_task.is_narrow()) {
4944 pss->deal_with_reference((narrowOop*) stolen_task);
4945 } else {
4946 pss->deal_with_reference((oop*) stolen_task);
4947 }
4948
4949 // We've just processed a reference and we might have made
4950 // available new entries on the queues. So we have to make sure
4951 // we drain the queues as necessary.
4952 pss->trim_queue();
4953 }
4954 } while (!offer_termination());
4955
4956 pss->retire_alloc_buffers();
4957 }
4958
4959 class G1KlassScanClosure : public KlassClosure {
4960 G1ParCopyHelper* _closure;
4961 bool _process_only_dirty;
4962 int _count;
4963 public:
4964 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4965 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4966 void do_klass(Klass* klass) {
4967 // If the klass has not been dirtied we know that there's
4968 // no references into the young gen and we can skip it.
4969 if (!_process_only_dirty || klass->has_modified_oops()) {
4970 // Clean the klass since we're going to scavenge all the metadata.
4971 klass->clear_modified_oops();
4972
4973 // Tell the closure that this klass is the Klass to scavenge
4974 // and is the one to dirty if oops are left pointing into the young gen.
4975 _closure->set_scanned_klass(klass);
4976
4977 klass->oops_do(_closure);
4978
4979 _closure->set_scanned_klass(NULL);
4980 }
4981 _count++;
4982 }
4983 };
4984
4985 class G1ParTask : public AbstractGangTask {
4986 protected:
4987 G1CollectedHeap* _g1h;
4988 RefToScanQueueSet *_queues;
4989 ParallelTaskTerminator _terminator;
4990 uint _n_workers;
4991
4992 Mutex _stats_lock;
4993 Mutex* stats_lock() { return &_stats_lock; }
4994
4995 size_t getNCards() {
4996 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4997 / G1BlockOffsetSharedArray::N_bytes;
4998 }
4999
5000 public:
5001 G1ParTask(G1CollectedHeap* g1h,
5002 RefToScanQueueSet *task_queues)
5003 : AbstractGangTask("G1 collection"),
5004 _g1h(g1h),
5005 _queues(task_queues),
5006 _terminator(0, _queues),
5007 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
5008 {}
5009
5010 RefToScanQueueSet* queues() { return _queues; }
5011
5012 RefToScanQueue *work_queue(int i) {
5013 return queues()->queue(i);
5014 }
5015
5016 ParallelTaskTerminator* terminator() { return &_terminator; }
5017
5018 virtual void set_for_termination(int active_workers) {
5019 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5020 // in the young space (_par_seq_tasks) in the G1 heap
5021 // for SequentialSubTasksDone.
5022 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5023 // both of which need setting by set_n_termination().
5024 _g1h->SharedHeap::set_n_termination(active_workers);
5025 _g1h->set_n_termination(active_workers);
5026 terminator()->reset_for_reuse(active_workers);
5027 _n_workers = active_workers;
5028 }
5029
5030 void work(uint worker_id) {
5031 if (worker_id >= _n_workers) return; // no work needed this round
5032
5033 double start_time_ms = os::elapsedTime() * 1000.0;
5034 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5035
5036 {
5037 ResourceMark rm;
5038 HandleMark hm;
5039
5040 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5041
5042 G1ParScanThreadState pss(_g1h, worker_id);
5043 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5044 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5045 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5046
5047 pss.set_evac_closure(&scan_evac_cl);
5048 pss.set_evac_failure_closure(&evac_failure_cl);
5049 pss.set_partial_scan_closure(&partial_scan_cl);
5050
5051 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5052 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5053
5054 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5055 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5056
5057 bool only_young = _g1h->g1_policy()->gcs_are_young();
5058 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5059 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5060
5061 OopClosure* scan_root_cl = &only_scan_root_cl;
5062 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5063
5064 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5065 // We also need to mark copied objects.
5066 scan_root_cl = &scan_mark_root_cl;
5067 scan_klasses_cl = &scan_mark_klasses_cl_s;
5068 }
5069
5070 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5071
5072 // Don't scan the scavengable methods in the code cache as part
5073 // of strong root scanning. The code roots that point into a
5074 // region in the collection set are scanned when we scan the
5075 // region's RSet.
5076 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5077
5078 pss.start_strong_roots();
5079 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5080 SharedHeap::ScanningOption(so),
5081 scan_root_cl,
5082 &push_heap_rs_cl,
5083 scan_klasses_cl,
5084 worker_id);
5085 pss.end_strong_roots();
5086
5087 {
5088 double start = os::elapsedTime();
5089 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5090 evac.do_void();
5091 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5092 double term_ms = pss.term_time()*1000.0;
5093 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5094 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5095 }
5096 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5097 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5098
5099 if (ParallelGCVerbose) {
5100 MutexLocker x(stats_lock());
5101 pss.print_termination_stats(worker_id);
5102 }
5103
5104 assert(pss.refs()->is_empty(), "should be empty");
5105
5106 // Close the inner scope so that the ResourceMark and HandleMark
5107 // destructors are executed here and are included as part of the
5108 // "GC Worker Time".
5109 }
5110
5111 double end_time_ms = os::elapsedTime() * 1000.0;
5112 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5113 }
5114 };
5115
5116 // *** Common G1 Evacuation Stuff
5117
5118 // This method is run in a GC worker.
5119
5120 void
5121 G1CollectedHeap::
5122 g1_process_strong_roots(bool is_scavenging,
5123 ScanningOption so,
5124 OopClosure* scan_non_heap_roots,
5125 OopsInHeapRegionClosure* scan_rs,
5126 G1KlassScanClosure* scan_klasses,
5127 int worker_i) {
5128
5129 // First scan the strong roots
5130 double ext_roots_start = os::elapsedTime();
5131 double closure_app_time_sec = 0.0;
5132
5133 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5134
5135 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5136 // Walk the code cache/strong code roots w/o buffering, because StarTask
5137 // cannot handle unaligned oop locations.
5138 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5139
5140 process_strong_roots(false, // no scoping; this is parallel code
5141 is_scavenging, so,
5142 &buf_scan_non_heap_roots,
5143 &eager_scan_code_roots,
5144 scan_klasses
5145 );
5146
5147 // Now the CM ref_processor roots.
5148 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5149 // We need to treat the discovered reference lists of the
5150 // concurrent mark ref processor as roots and keep entries
5151 // (which are added by the marking threads) on them live
5152 // until they can be processed at the end of marking.
5153 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5154 }
5155
5156 // Finish up any enqueued closure apps (attributed as object copy time).
5157 buf_scan_non_heap_roots.done();
5158
5159 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5160
5161 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5162
5163 double ext_root_time_ms =
5164 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5165
5166 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5167
5168 // During conc marking we have to filter the per-thread SATB buffers
5169 // to make sure we remove any oops into the CSet (which will show up
5170 // as implicitly live).
5171 double satb_filtering_ms = 0.0;
5172 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5173 if (mark_in_progress()) {
5174 double satb_filter_start = os::elapsedTime();
5175
5176 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5177
5178 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5179 }
5180 }
5181 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5182
5183 // If this is an initial mark pause, and we're not scanning
5184 // the entire code cache, we need to mark the oops in the
5185 // strong code root lists for the regions that are not in
5186 // the collection set.
5187 // Note all threads participate in this set of root tasks.
5188 double mark_strong_code_roots_ms = 0.0;
5189 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5190 double mark_strong_roots_start = os::elapsedTime();
5191 mark_strong_code_roots(worker_i);
5192 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5193 }
5194 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5195
5196 // Now scan the complement of the collection set.
5197 if (scan_rs != NULL) {
5198 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5199 }
5200 _process_strong_tasks->all_tasks_completed();
5201 }
5202
5203 void
5204 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5205 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5206 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5207 }
5208
5209 // Weak Reference Processing support
5210
5211 // An always "is_alive" closure that is used to preserve referents.
5212 // If the object is non-null then it's alive. Used in the preservation
5213 // of referent objects that are pointed to by reference objects
5214 // discovered by the CM ref processor.
5215 class G1AlwaysAliveClosure: public BoolObjectClosure {
5216 G1CollectedHeap* _g1;
5217 public:
5218 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5219 bool do_object_b(oop p) {
5220 if (p != NULL) {
5221 return true;
5222 }
5223 return false;
5224 }
5225 };
5226
5227 bool G1STWIsAliveClosure::do_object_b(oop p) {
5228 // An object is reachable if it is outside the collection set,
5229 // or is inside and copied.
5230 return !_g1->obj_in_cs(p) || p->is_forwarded();
5231 }
5232
5233 // Non Copying Keep Alive closure
5234 class G1KeepAliveClosure: public OopClosure {
5235 G1CollectedHeap* _g1;
5236 public:
5237 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5238 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5239 void do_oop( oop* p) {
5240 oop obj = *p;
5241
5242 if (_g1->obj_in_cs(obj)) {
5243 assert( obj->is_forwarded(), "invariant" );
5244 *p = obj->forwardee();
5245 }
5246 }
5247 };
5248
5249 // Copying Keep Alive closure - can be called from both
5250 // serial and parallel code as long as different worker
5251 // threads utilize different G1ParScanThreadState instances
5252 // and different queues.
5253
5254 class G1CopyingKeepAliveClosure: public OopClosure {
5255 G1CollectedHeap* _g1h;
5256 OopClosure* _copy_non_heap_obj_cl;
5257 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5258 G1ParScanThreadState* _par_scan_state;
5259
5260 public:
5261 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5262 OopClosure* non_heap_obj_cl,
5263 OopsInHeapRegionClosure* metadata_obj_cl,
5264 G1ParScanThreadState* pss):
5265 _g1h(g1h),
5266 _copy_non_heap_obj_cl(non_heap_obj_cl),
5267 _copy_metadata_obj_cl(metadata_obj_cl),
5268 _par_scan_state(pss)
5269 {}
5270
5271 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5272 virtual void do_oop( oop* p) { do_oop_work(p); }
5273
5274 template <class T> void do_oop_work(T* p) {
5275 oop obj = oopDesc::load_decode_heap_oop(p);
5276
5277 if (_g1h->obj_in_cs(obj)) {
5278 // If the referent object has been forwarded (either copied
5279 // to a new location or to itself in the event of an
5280 // evacuation failure) then we need to update the reference
5281 // field and, if both reference and referent are in the G1
5282 // heap, update the RSet for the referent.
5283 //
5284 // If the referent has not been forwarded then we have to keep
5285 // it alive by policy. Therefore we have copy the referent.
5286 //
5287 // If the reference field is in the G1 heap then we can push
5288 // on the PSS queue. When the queue is drained (after each
5289 // phase of reference processing) the object and it's followers
5290 // will be copied, the reference field set to point to the
5291 // new location, and the RSet updated. Otherwise we need to
5292 // use the the non-heap or metadata closures directly to copy
5293 // the referent object and update the pointer, while avoiding
5294 // updating the RSet.
5295
5296 if (_g1h->is_in_g1_reserved(p)) {
5297 _par_scan_state->push_on_queue(p);
5298 } else {
5299 assert(!ClassLoaderDataGraph::contains((address)p),
5300 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5301 PTR_FORMAT, p));
5302 _copy_non_heap_obj_cl->do_oop(p);
5303 }
5304 }
5305 }
5306 };
5307
5308 // Serial drain queue closure. Called as the 'complete_gc'
5309 // closure for each discovered list in some of the
5310 // reference processing phases.
5311
5312 class G1STWDrainQueueClosure: public VoidClosure {
5313 protected:
5314 G1CollectedHeap* _g1h;
5315 G1ParScanThreadState* _par_scan_state;
5316
5317 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5318
5319 public:
5320 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5321 _g1h(g1h),
5322 _par_scan_state(pss)
5323 { }
5324
5325 void do_void() {
5326 G1ParScanThreadState* const pss = par_scan_state();
5327 pss->trim_queue();
5328 }
5329 };
5330
5331 // Parallel Reference Processing closures
5332
5333 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5334 // processing during G1 evacuation pauses.
5335
5336 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5337 private:
5338 G1CollectedHeap* _g1h;
5339 RefToScanQueueSet* _queues;
5340 FlexibleWorkGang* _workers;
5341 int _active_workers;
5342
5343 public:
5344 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5345 FlexibleWorkGang* workers,
5346 RefToScanQueueSet *task_queues,
5347 int n_workers) :
5348 _g1h(g1h),
5349 _queues(task_queues),
5350 _workers(workers),
5351 _active_workers(n_workers)
5352 {
5353 assert(n_workers > 0, "shouldn't call this otherwise");
5354 }
5355
5356 // Executes the given task using concurrent marking worker threads.
5357 virtual void execute(ProcessTask& task);
5358 virtual void execute(EnqueueTask& task);
5359 };
5360
5361 // Gang task for possibly parallel reference processing
5362
5363 class G1STWRefProcTaskProxy: public AbstractGangTask {
5364 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5365 ProcessTask& _proc_task;
5366 G1CollectedHeap* _g1h;
5367 RefToScanQueueSet *_task_queues;
5368 ParallelTaskTerminator* _terminator;
5369
5370 public:
5371 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5372 G1CollectedHeap* g1h,
5373 RefToScanQueueSet *task_queues,
5374 ParallelTaskTerminator* terminator) :
5375 AbstractGangTask("Process reference objects in parallel"),
5376 _proc_task(proc_task),
5377 _g1h(g1h),
5378 _task_queues(task_queues),
5379 _terminator(terminator)
5380 {}
5381
5382 virtual void work(uint worker_id) {
5383 // The reference processing task executed by a single worker.
5384 ResourceMark rm;
5385 HandleMark hm;
5386
5387 G1STWIsAliveClosure is_alive(_g1h);
5388
5389 G1ParScanThreadState pss(_g1h, worker_id);
5390
5391 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5392 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5393 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5394
5395 pss.set_evac_closure(&scan_evac_cl);
5396 pss.set_evac_failure_closure(&evac_failure_cl);
5397 pss.set_partial_scan_closure(&partial_scan_cl);
5398
5399 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5400 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5401
5402 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5403 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5404
5405 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5406 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5407
5408 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5409 // We also need to mark copied objects.
5410 copy_non_heap_cl = ©_mark_non_heap_cl;
5411 copy_metadata_cl = ©_mark_metadata_cl;
5412 }
5413
5414 // Keep alive closure.
5415 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5416
5417 // Complete GC closure
5418 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5419
5420 // Call the reference processing task's work routine.
5421 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5422
5423 // Note we cannot assert that the refs array is empty here as not all
5424 // of the processing tasks (specifically phase2 - pp2_work) execute
5425 // the complete_gc closure (which ordinarily would drain the queue) so
5426 // the queue may not be empty.
5427 }
5428 };
5429
5430 // Driver routine for parallel reference processing.
5431 // Creates an instance of the ref processing gang
5432 // task and has the worker threads execute it.
5433 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5434 assert(_workers != NULL, "Need parallel worker threads.");
5435
5436 ParallelTaskTerminator terminator(_active_workers, _queues);
5437 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5438
5439 _g1h->set_par_threads(_active_workers);
5440 _workers->run_task(&proc_task_proxy);
5441 _g1h->set_par_threads(0);
5442 }
5443
5444 // Gang task for parallel reference enqueueing.
5445
5446 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5447 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5448 EnqueueTask& _enq_task;
5449
5450 public:
5451 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5452 AbstractGangTask("Enqueue reference objects in parallel"),
5453 _enq_task(enq_task)
5454 { }
5455
5456 virtual void work(uint worker_id) {
5457 _enq_task.work(worker_id);
5458 }
5459 };
5460
5461 // Driver routine for parallel reference enqueueing.
5462 // Creates an instance of the ref enqueueing gang
5463 // task and has the worker threads execute it.
5464
5465 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5466 assert(_workers != NULL, "Need parallel worker threads.");
5467
5468 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5469
5470 _g1h->set_par_threads(_active_workers);
5471 _workers->run_task(&enq_task_proxy);
5472 _g1h->set_par_threads(0);
5473 }
5474
5475 // End of weak reference support closures
5476
5477 // Abstract task used to preserve (i.e. copy) any referent objects
5478 // that are in the collection set and are pointed to by reference
5479 // objects discovered by the CM ref processor.
5480
5481 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5482 protected:
5483 G1CollectedHeap* _g1h;
5484 RefToScanQueueSet *_queues;
5485 ParallelTaskTerminator _terminator;
5486 uint _n_workers;
5487
5488 public:
5489 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5490 AbstractGangTask("ParPreserveCMReferents"),
5491 _g1h(g1h),
5492 _queues(task_queues),
5493 _terminator(workers, _queues),
5494 _n_workers(workers)
5495 { }
5496
5497 void work(uint worker_id) {
5498 ResourceMark rm;
5499 HandleMark hm;
5500
5501 G1ParScanThreadState pss(_g1h, worker_id);
5502 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5503 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5504 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5505
5506 pss.set_evac_closure(&scan_evac_cl);
5507 pss.set_evac_failure_closure(&evac_failure_cl);
5508 pss.set_partial_scan_closure(&partial_scan_cl);
5509
5510 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5511
5512
5513 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5514 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5515
5516 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5517 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5518
5519 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5520 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5521
5522 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5523 // We also need to mark copied objects.
5524 copy_non_heap_cl = ©_mark_non_heap_cl;
5525 copy_metadata_cl = ©_mark_metadata_cl;
5526 }
5527
5528 // Is alive closure
5529 G1AlwaysAliveClosure always_alive(_g1h);
5530
5531 // Copying keep alive closure. Applied to referent objects that need
5532 // to be copied.
5533 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5534
5535 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5536
5537 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5538 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5539
5540 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5541 // So this must be true - but assert just in case someone decides to
5542 // change the worker ids.
5543 assert(0 <= worker_id && worker_id < limit, "sanity");
5544 assert(!rp->discovery_is_atomic(), "check this code");
5545
5546 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5547 for (uint idx = worker_id; idx < limit; idx += stride) {
5548 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5549
5550 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5551 while (iter.has_next()) {
5552 // Since discovery is not atomic for the CM ref processor, we
5553 // can see some null referent objects.
5554 iter.load_ptrs(DEBUG_ONLY(true));
5555 oop ref = iter.obj();
5556
5557 // This will filter nulls.
5558 if (iter.is_referent_alive()) {
5559 iter.make_referent_alive();
5560 }
5561 iter.move_to_next();
5562 }
5563 }
5564
5565 // Drain the queue - which may cause stealing
5566 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5567 drain_queue.do_void();
5568 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5569 assert(pss.refs()->is_empty(), "should be");
5570 }
5571 };
5572
5573 // Weak Reference processing during an evacuation pause (part 1).
5574 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5575 double ref_proc_start = os::elapsedTime();
5576
5577 ReferenceProcessor* rp = _ref_processor_stw;
5578 assert(rp->discovery_enabled(), "should have been enabled");
5579
5580 // Any reference objects, in the collection set, that were 'discovered'
5581 // by the CM ref processor should have already been copied (either by
5582 // applying the external root copy closure to the discovered lists, or
5583 // by following an RSet entry).
5584 //
5585 // But some of the referents, that are in the collection set, that these
5586 // reference objects point to may not have been copied: the STW ref
5587 // processor would have seen that the reference object had already
5588 // been 'discovered' and would have skipped discovering the reference,
5589 // but would not have treated the reference object as a regular oop.
5590 // As a result the copy closure would not have been applied to the
5591 // referent object.
5592 //
5593 // We need to explicitly copy these referent objects - the references
5594 // will be processed at the end of remarking.
5595 //
5596 // We also need to do this copying before we process the reference
5597 // objects discovered by the STW ref processor in case one of these
5598 // referents points to another object which is also referenced by an
5599 // object discovered by the STW ref processor.
5600
5601 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5602 no_of_gc_workers == workers()->active_workers(),
5603 "Need to reset active GC workers");
5604
5605 set_par_threads(no_of_gc_workers);
5606 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5607 no_of_gc_workers,
5608 _task_queues);
5609
5610 if (G1CollectedHeap::use_parallel_gc_threads()) {
5611 workers()->run_task(&keep_cm_referents);
5612 } else {
5613 keep_cm_referents.work(0);
5614 }
5615
5616 set_par_threads(0);
5617
5618 // Closure to test whether a referent is alive.
5619 G1STWIsAliveClosure is_alive(this);
5620
5621 // Even when parallel reference processing is enabled, the processing
5622 // of JNI refs is serial and performed serially by the current thread
5623 // rather than by a worker. The following PSS will be used for processing
5624 // JNI refs.
5625
5626 // Use only a single queue for this PSS.
5627 G1ParScanThreadState pss(this, 0);
5628
5629 // We do not embed a reference processor in the copying/scanning
5630 // closures while we're actually processing the discovered
5631 // reference objects.
5632 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5633 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5634 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5635
5636 pss.set_evac_closure(&scan_evac_cl);
5637 pss.set_evac_failure_closure(&evac_failure_cl);
5638 pss.set_partial_scan_closure(&partial_scan_cl);
5639
5640 assert(pss.refs()->is_empty(), "pre-condition");
5641
5642 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5643 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5644
5645 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5646 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5647
5648 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5649 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5650
5651 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5652 // We also need to mark copied objects.
5653 copy_non_heap_cl = ©_mark_non_heap_cl;
5654 copy_metadata_cl = ©_mark_metadata_cl;
5655 }
5656
5657 // Keep alive closure.
5658 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5659
5660 // Serial Complete GC closure
5661 G1STWDrainQueueClosure drain_queue(this, &pss);
5662
5663 // Setup the soft refs policy...
5664 rp->setup_policy(false);
5665
5666 ReferenceProcessorStats stats;
5667 if (!rp->processing_is_mt()) {
5668 // Serial reference processing...
5669 stats = rp->process_discovered_references(&is_alive,
5670 &keep_alive,
5671 &drain_queue,
5672 NULL,
5673 _gc_timer_stw);
5674 } else {
5675 // Parallel reference processing
5676 assert(rp->num_q() == no_of_gc_workers, "sanity");
5677 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5678
5679 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5680 stats = rp->process_discovered_references(&is_alive,
5681 &keep_alive,
5682 &drain_queue,
5683 &par_task_executor,
5684 _gc_timer_stw);
5685 }
5686
5687 _gc_tracer_stw->report_gc_reference_stats(stats);
5688 // We have completed copying any necessary live referent objects
5689 // (that were not copied during the actual pause) so we can
5690 // retire any active alloc buffers
5691 pss.retire_alloc_buffers();
5692 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5693
5694 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5695 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5696 }
5697
5698 // Weak Reference processing during an evacuation pause (part 2).
5699 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5700 double ref_enq_start = os::elapsedTime();
5701
5702 ReferenceProcessor* rp = _ref_processor_stw;
5703 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5704
5705 // Now enqueue any remaining on the discovered lists on to
5706 // the pending list.
5707 if (!rp->processing_is_mt()) {
5708 // Serial reference processing...
5709 rp->enqueue_discovered_references();
5710 } else {
5711 // Parallel reference enqueueing
5712
5713 assert(no_of_gc_workers == workers()->active_workers(),
5714 "Need to reset active workers");
5715 assert(rp->num_q() == no_of_gc_workers, "sanity");
5716 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5717
5718 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5719 rp->enqueue_discovered_references(&par_task_executor);
5720 }
5721
5722 rp->verify_no_references_recorded();
5723 assert(!rp->discovery_enabled(), "should have been disabled");
5724
5725 // FIXME
5726 // CM's reference processing also cleans up the string and symbol tables.
5727 // Should we do that here also? We could, but it is a serial operation
5728 // and could significantly increase the pause time.
5729
5730 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5731 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5732 }
5733
5734 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5735 _expand_heap_after_alloc_failure = true;
5736 _evacuation_failed = false;
5737
5738 // Should G1EvacuationFailureALot be in effect for this GC?
5739 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5740
5741 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5742
5743 // Disable the hot card cache.
5744 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5745 hot_card_cache->reset_hot_cache_claimed_index();
5746 hot_card_cache->set_use_cache(false);
5747
5748 uint n_workers;
5749 if (G1CollectedHeap::use_parallel_gc_threads()) {
5750 n_workers =
5751 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5752 workers()->active_workers(),
5753 Threads::number_of_non_daemon_threads());
5754 assert(UseDynamicNumberOfGCThreads ||
5755 n_workers == workers()->total_workers(),
5756 "If not dynamic should be using all the workers");
5757 workers()->set_active_workers(n_workers);
5758 set_par_threads(n_workers);
5759 } else {
5760 assert(n_par_threads() == 0,
5761 "Should be the original non-parallel value");
5762 n_workers = 1;
5763 }
5764
5765 G1ParTask g1_par_task(this, _task_queues);
5766
5767 init_for_evac_failure(NULL);
5768
5769 rem_set()->prepare_for_younger_refs_iterate(true);
5770
5771 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5772 double start_par_time_sec = os::elapsedTime();
5773 double end_par_time_sec;
5774
5775 {
5776 StrongRootsScope srs(this);
5777
5778 if (G1CollectedHeap::use_parallel_gc_threads()) {
5779 // The individual threads will set their evac-failure closures.
5780 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5781 // These tasks use ShareHeap::_process_strong_tasks
5782 assert(UseDynamicNumberOfGCThreads ||
5783 workers()->active_workers() == workers()->total_workers(),
5784 "If not dynamic should be using all the workers");
5785 workers()->run_task(&g1_par_task);
5786 } else {
5787 g1_par_task.set_for_termination(n_workers);
5788 g1_par_task.work(0);
5789 }
5790 end_par_time_sec = os::elapsedTime();
5791
5792 // Closing the inner scope will execute the destructor
5793 // for the StrongRootsScope object. We record the current
5794 // elapsed time before closing the scope so that time
5795 // taken for the SRS destructor is NOT included in the
5796 // reported parallel time.
5797 }
5798
5799 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5800 g1_policy()->phase_times()->record_par_time(par_time_ms);
5801
5802 double code_root_fixup_time_ms =
5803 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5804 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5805
5806 set_par_threads(0);
5807
5808 // Process any discovered reference objects - we have
5809 // to do this _before_ we retire the GC alloc regions
5810 // as we may have to copy some 'reachable' referent
5811 // objects (and their reachable sub-graphs) that were
5812 // not copied during the pause.
5813 process_discovered_references(n_workers);
5814
5815 // Weak root processing.
5816 {
5817 G1STWIsAliveClosure is_alive(this);
5818 G1KeepAliveClosure keep_alive(this);
5819 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5820 }
5821
5822 release_gc_alloc_regions(n_workers, evacuation_info);
5823 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5824
5825 // Reset and re-enable the hot card cache.
5826 // Note the counts for the cards in the regions in the
5827 // collection set are reset when the collection set is freed.
5828 hot_card_cache->reset_hot_cache();
5829 hot_card_cache->set_use_cache(true);
5830
5831 // Migrate the strong code roots attached to each region in
5832 // the collection set. Ideally we would like to do this
5833 // after we have finished the scanning/evacuation of the
5834 // strong code roots for a particular heap region.
5835 migrate_strong_code_roots();
5836
5837 if (g1_policy()->during_initial_mark_pause()) {
5838 // Reset the claim values set during marking the strong code roots
5839 reset_heap_region_claim_values();
5840 }
5841
5842 finalize_for_evac_failure();
5843
5844 if (evacuation_failed()) {
5845 remove_self_forwarding_pointers();
5846
5847 // Reset the G1EvacuationFailureALot counters and flags
5848 // Note: the values are reset only when an actual
5849 // evacuation failure occurs.
5850 NOT_PRODUCT(reset_evacuation_should_fail();)
5851 }
5852
5853 // Enqueue any remaining references remaining on the STW
5854 // reference processor's discovered lists. We need to do
5855 // this after the card table is cleaned (and verified) as
5856 // the act of enqueueing entries on to the pending list
5857 // will log these updates (and dirty their associated
5858 // cards). We need these updates logged to update any
5859 // RSets.
5860 enqueue_discovered_references(n_workers);
5861
5862 if (G1DeferredRSUpdate) {
5863 RedirtyLoggedCardTableEntryFastClosure redirty;
5864 dirty_card_queue_set().set_closure(&redirty);
5865 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5866
5867 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5868 dcq.merge_bufferlists(&dirty_card_queue_set());
5869 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5870 }
5871 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5872 }
5873
5874 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5875 size_t* pre_used,
5876 FreeRegionList* free_list,
5877 OldRegionSet* old_proxy_set,
5878 HumongousRegionSet* humongous_proxy_set,
5879 HRRSCleanupTask* hrrs_cleanup_task,
5880 bool par) {
5881 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5882 if (hr->isHumongous()) {
5883 assert(hr->startsHumongous(), "we should only see starts humongous");
5884 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5885 } else {
5886 _old_set.remove_with_proxy(hr, old_proxy_set);
5887 free_region(hr, pre_used, free_list, par);
5888 }
5889 } else {
5890 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5891 }
5892 }
5893
5894 void G1CollectedHeap::free_region(HeapRegion* hr,
5895 size_t* pre_used,
5896 FreeRegionList* free_list,
5897 bool par) {
5898 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5899 assert(!hr->is_empty(), "the region should not be empty");
5900 assert(free_list != NULL, "pre-condition");
5901
5902 // Clear the card counts for this region.
5903 // Note: we only need to do this if the region is not young
5904 // (since we don't refine cards in young regions).
5905 if (!hr->is_young()) {
5906 _cg1r->hot_card_cache()->reset_card_counts(hr);
5907 }
5908 *pre_used += hr->used();
5909 hr->hr_clear(par, true /* clear_space */);
5910 free_list->add_as_head(hr);
5911 }
5912
5913 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5914 size_t* pre_used,
5915 FreeRegionList* free_list,
5916 HumongousRegionSet* humongous_proxy_set,
5917 bool par) {
5918 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5919 assert(free_list != NULL, "pre-condition");
5920 assert(humongous_proxy_set != NULL, "pre-condition");
5921
5922 size_t hr_used = hr->used();
5923 size_t hr_capacity = hr->capacity();
5924 size_t hr_pre_used = 0;
5925 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5926 // We need to read this before we make the region non-humongous,
5927 // otherwise the information will be gone.
5928 uint last_index = hr->last_hc_index();
5929 hr->set_notHumongous();
5930 free_region(hr, &hr_pre_used, free_list, par);
5931
5932 uint i = hr->hrs_index() + 1;
5933 while (i < last_index) {
5934 HeapRegion* curr_hr = region_at(i);
5935 assert(curr_hr->continuesHumongous(), "invariant");
5936 curr_hr->set_notHumongous();
5937 free_region(curr_hr, &hr_pre_used, free_list, par);
5938 i += 1;
5939 }
5940 assert(hr_pre_used == hr_used,
5941 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5942 "should be the same", hr_pre_used, hr_used));
5943 *pre_used += hr_pre_used;
5944 }
5945
5946 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5947 FreeRegionList* free_list,
5948 OldRegionSet* old_proxy_set,
5949 HumongousRegionSet* humongous_proxy_set,
5950 bool par) {
5951 if (pre_used > 0) {
5952 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5953 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5954 assert(_summary_bytes_used >= pre_used,
5955 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5956 "should be >= pre_used: "SIZE_FORMAT,
5957 _summary_bytes_used, pre_used));
5958 _summary_bytes_used -= pre_used;
5959 }
5960 if (free_list != NULL && !free_list->is_empty()) {
5961 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5962 _free_list.add_as_head(free_list);
5963 }
5964 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5965 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5966 _old_set.update_from_proxy(old_proxy_set);
5967 }
5968 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5969 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5970 _humongous_set.update_from_proxy(humongous_proxy_set);
5971 }
5972 }
5973
5974 class G1ParCleanupCTTask : public AbstractGangTask {
5975 G1SATBCardTableModRefBS* _ct_bs;
5976 G1CollectedHeap* _g1h;
5977 HeapRegion* volatile _su_head;
5978 public:
5979 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5980 G1CollectedHeap* g1h) :
5981 AbstractGangTask("G1 Par Cleanup CT Task"),
5982 _ct_bs(ct_bs), _g1h(g1h) { }
5983
5984 void work(uint worker_id) {
5985 HeapRegion* r;
5986 while (r = _g1h->pop_dirty_cards_region()) {
5987 clear_cards(r);
5988 }
5989 }
5990
5991 void clear_cards(HeapRegion* r) {
5992 // Cards of the survivors should have already been dirtied.
5993 if (!r->is_survivor()) {
5994 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5995 }
5996 }
5997 };
5998
5999 #ifndef PRODUCT
6000 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6001 G1CollectedHeap* _g1h;
6002 G1SATBCardTableModRefBS* _ct_bs;
6003 public:
6004 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6005 : _g1h(g1h), _ct_bs(ct_bs) { }
6006 virtual bool doHeapRegion(HeapRegion* r) {
6007 if (r->is_survivor()) {
6008 _g1h->verify_dirty_region(r);
6009 } else {
6010 _g1h->verify_not_dirty_region(r);
6011 }
6012 return false;
6013 }
6014 };
6015
6016 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6017 // All of the region should be clean.
6018 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6019 MemRegion mr(hr->bottom(), hr->end());
6020 ct_bs->verify_not_dirty_region(mr);
6021 }
6022
6023 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6024 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6025 // dirty allocated blocks as they allocate them. The thread that
6026 // retires each region and replaces it with a new one will do a
6027 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6028 // not dirty that area (one less thing to have to do while holding
6029 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6030 // is dirty.
6031 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6032 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6033 ct_bs->verify_dirty_region(mr);
6034 }
6035
6036 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6037 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6038 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6039 verify_dirty_region(hr);
6040 }
6041 }
6042
6043 void G1CollectedHeap::verify_dirty_young_regions() {
6044 verify_dirty_young_list(_young_list->first_region());
6045 }
6046 #endif
6047
6048 void G1CollectedHeap::cleanUpCardTable() {
6049 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6050 double start = os::elapsedTime();
6051
6052 {
6053 // Iterate over the dirty cards region list.
6054 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6055
6056 if (G1CollectedHeap::use_parallel_gc_threads()) {
6057 set_par_threads();
6058 workers()->run_task(&cleanup_task);
6059 set_par_threads(0);
6060 } else {
6061 while (_dirty_cards_region_list) {
6062 HeapRegion* r = _dirty_cards_region_list;
6063 cleanup_task.clear_cards(r);
6064 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6065 if (_dirty_cards_region_list == r) {
6066 // The last region.
6067 _dirty_cards_region_list = NULL;
6068 }
6069 r->set_next_dirty_cards_region(NULL);
6070 }
6071 }
6072 #ifndef PRODUCT
6073 if (G1VerifyCTCleanup || VerifyAfterGC) {
6074 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6075 heap_region_iterate(&cleanup_verifier);
6076 }
6077 #endif
6078 }
6079
6080 double elapsed = os::elapsedTime() - start;
6081 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6082 }
6083
6084 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6085 size_t pre_used = 0;
6086 FreeRegionList local_free_list("Local List for CSet Freeing");
6087
6088 double young_time_ms = 0.0;
6089 double non_young_time_ms = 0.0;
6090
6091 // Since the collection set is a superset of the the young list,
6092 // all we need to do to clear the young list is clear its
6093 // head and length, and unlink any young regions in the code below
6094 _young_list->clear();
6095
6096 G1CollectorPolicy* policy = g1_policy();
6097
6098 double start_sec = os::elapsedTime();
6099 bool non_young = true;
6100
6101 HeapRegion* cur = cs_head;
6102 int age_bound = -1;
6103 size_t rs_lengths = 0;
6104
6105 while (cur != NULL) {
6106 assert(!is_on_master_free_list(cur), "sanity");
6107 if (non_young) {
6108 if (cur->is_young()) {
6109 double end_sec = os::elapsedTime();
6110 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6111 non_young_time_ms += elapsed_ms;
6112
6113 start_sec = os::elapsedTime();
6114 non_young = false;
6115 }
6116 } else {
6117 if (!cur->is_young()) {
6118 double end_sec = os::elapsedTime();
6119 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6120 young_time_ms += elapsed_ms;
6121
6122 start_sec = os::elapsedTime();
6123 non_young = true;
6124 }
6125 }
6126
6127 rs_lengths += cur->rem_set()->occupied();
6128
6129 HeapRegion* next = cur->next_in_collection_set();
6130 assert(cur->in_collection_set(), "bad CS");
6131 cur->set_next_in_collection_set(NULL);
6132 cur->set_in_collection_set(false);
6133
6134 if (cur->is_young()) {
6135 int index = cur->young_index_in_cset();
6136 assert(index != -1, "invariant");
6137 assert((uint) index < policy->young_cset_region_length(), "invariant");
6138 size_t words_survived = _surviving_young_words[index];
6139 cur->record_surv_words_in_group(words_survived);
6140
6141 // At this point the we have 'popped' cur from the collection set
6142 // (linked via next_in_collection_set()) but it is still in the
6143 // young list (linked via next_young_region()). Clear the
6144 // _next_young_region field.
6145 cur->set_next_young_region(NULL);
6146 } else {
6147 int index = cur->young_index_in_cset();
6148 assert(index == -1, "invariant");
6149 }
6150
6151 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6152 (!cur->is_young() && cur->young_index_in_cset() == -1),
6153 "invariant" );
6154
6155 if (!cur->evacuation_failed()) {
6156 MemRegion used_mr = cur->used_region();
6157
6158 // And the region is empty.
6159 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6160 free_region(cur, &pre_used, &local_free_list, false /* par */);
6161 } else {
6162 cur->uninstall_surv_rate_group();
6163 if (cur->is_young()) {
6164 cur->set_young_index_in_cset(-1);
6165 }
6166 cur->set_not_young();
6167 cur->set_evacuation_failed(false);
6168 // The region is now considered to be old.
6169 _old_set.add(cur);
6170 evacuation_info.increment_collectionset_used_after(cur->used());
6171 }
6172 cur = next;
6173 }
6174
6175 evacuation_info.set_regions_freed(local_free_list.length());
6176 policy->record_max_rs_lengths(rs_lengths);
6177 policy->cset_regions_freed();
6178
6179 double end_sec = os::elapsedTime();
6180 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6181
6182 if (non_young) {
6183 non_young_time_ms += elapsed_ms;
6184 } else {
6185 young_time_ms += elapsed_ms;
6186 }
6187
6188 update_sets_after_freeing_regions(pre_used, &local_free_list,
6189 NULL /* old_proxy_set */,
6190 NULL /* humongous_proxy_set */,
6191 false /* par */);
6192 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6193 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6194 }
6195
6196 // This routine is similar to the above but does not record
6197 // any policy statistics or update free lists; we are abandoning
6198 // the current incremental collection set in preparation of a
6199 // full collection. After the full GC we will start to build up
6200 // the incremental collection set again.
6201 // This is only called when we're doing a full collection
6202 // and is immediately followed by the tearing down of the young list.
6203
6204 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6205 HeapRegion* cur = cs_head;
6206
6207 while (cur != NULL) {
6208 HeapRegion* next = cur->next_in_collection_set();
6209 assert(cur->in_collection_set(), "bad CS");
6210 cur->set_next_in_collection_set(NULL);
6211 cur->set_in_collection_set(false);
6212 cur->set_young_index_in_cset(-1);
6213 cur = next;
6214 }
6215 }
6216
6217 void G1CollectedHeap::set_free_regions_coming() {
6218 if (G1ConcRegionFreeingVerbose) {
6219 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6220 "setting free regions coming");
6221 }
6222
6223 assert(!free_regions_coming(), "pre-condition");
6224 _free_regions_coming = true;
6225 }
6226
6227 void G1CollectedHeap::reset_free_regions_coming() {
6228 assert(free_regions_coming(), "pre-condition");
6229
6230 {
6231 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6232 _free_regions_coming = false;
6233 SecondaryFreeList_lock->notify_all();
6234 }
6235
6236 if (G1ConcRegionFreeingVerbose) {
6237 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6238 "reset free regions coming");
6239 }
6240 }
6241
6242 void G1CollectedHeap::wait_while_free_regions_coming() {
6243 // Most of the time we won't have to wait, so let's do a quick test
6244 // first before we take the lock.
6245 if (!free_regions_coming()) {
6246 return;
6247 }
6248
6249 if (G1ConcRegionFreeingVerbose) {
6250 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6251 "waiting for free regions");
6252 }
6253
6254 {
6255 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6256 while (free_regions_coming()) {
6257 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6258 }
6259 }
6260
6261 if (G1ConcRegionFreeingVerbose) {
6262 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6263 "done waiting for free regions");
6264 }
6265 }
6266
6267 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6268 assert(heap_lock_held_for_gc(),
6269 "the heap lock should already be held by or for this thread");
6270 _young_list->push_region(hr);
6271 }
6272
6273 class NoYoungRegionsClosure: public HeapRegionClosure {
6274 private:
6275 bool _success;
6276 public:
6277 NoYoungRegionsClosure() : _success(true) { }
6278 bool doHeapRegion(HeapRegion* r) {
6279 if (r->is_young()) {
6280 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6281 r->bottom(), r->end());
6282 _success = false;
6283 }
6284 return false;
6285 }
6286 bool success() { return _success; }
6287 };
6288
6289 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6290 bool ret = _young_list->check_list_empty(check_sample);
6291
6292 if (check_heap) {
6293 NoYoungRegionsClosure closure;
6294 heap_region_iterate(&closure);
6295 ret = ret && closure.success();
6296 }
6297
6298 return ret;
6299 }
6300
6301 class TearDownRegionSetsClosure : public HeapRegionClosure {
6302 private:
6303 OldRegionSet *_old_set;
6304
6305 public:
6306 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6307
6308 bool doHeapRegion(HeapRegion* r) {
6309 if (r->is_empty()) {
6310 // We ignore empty regions, we'll empty the free list afterwards
6311 } else if (r->is_young()) {
6312 // We ignore young regions, we'll empty the young list afterwards
6313 } else if (r->isHumongous()) {
6314 // We ignore humongous regions, we're not tearing down the
6315 // humongous region set
6316 } else {
6317 // The rest should be old
6318 _old_set->remove(r);
6319 }
6320 return false;
6321 }
6322
6323 ~TearDownRegionSetsClosure() {
6324 assert(_old_set->is_empty(), "post-condition");
6325 }
6326 };
6327
6328 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6329 assert_at_safepoint(true /* should_be_vm_thread */);
6330
6331 if (!free_list_only) {
6332 TearDownRegionSetsClosure cl(&_old_set);
6333 heap_region_iterate(&cl);
6334
6335 // Need to do this after the heap iteration to be able to
6336 // recognize the young regions and ignore them during the iteration.
6337 _young_list->empty_list();
6338 }
6339 _free_list.remove_all();
6340 }
6341
6342 class RebuildRegionSetsClosure : public HeapRegionClosure {
6343 private:
6344 bool _free_list_only;
6345 OldRegionSet* _old_set;
6346 FreeRegionList* _free_list;
6347 size_t _total_used;
6348
6349 public:
6350 RebuildRegionSetsClosure(bool free_list_only,
6351 OldRegionSet* old_set, FreeRegionList* free_list) :
6352 _free_list_only(free_list_only),
6353 _old_set(old_set), _free_list(free_list), _total_used(0) {
6354 assert(_free_list->is_empty(), "pre-condition");
6355 if (!free_list_only) {
6356 assert(_old_set->is_empty(), "pre-condition");
6357 }
6358 }
6359
6360 bool doHeapRegion(HeapRegion* r) {
6361 if (r->continuesHumongous()) {
6362 return false;
6363 }
6364
6365 if (r->is_empty()) {
6366 // Add free regions to the free list
6367 _free_list->add_as_tail(r);
6368 } else if (!_free_list_only) {
6369 assert(!r->is_young(), "we should not come across young regions");
6370
6371 if (r->isHumongous()) {
6372 // We ignore humongous regions, we left the humongous set unchanged
6373 } else {
6374 // The rest should be old, add them to the old set
6375 _old_set->add(r);
6376 }
6377 _total_used += r->used();
6378 }
6379
6380 return false;
6381 }
6382
6383 size_t total_used() {
6384 return _total_used;
6385 }
6386 };
6387
6388 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6389 assert_at_safepoint(true /* should_be_vm_thread */);
6390
6391 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6392 heap_region_iterate(&cl);
6393
6394 if (!free_list_only) {
6395 _summary_bytes_used = cl.total_used();
6396 }
6397 assert(_summary_bytes_used == recalculate_used(),
6398 err_msg("inconsistent _summary_bytes_used, "
6399 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6400 _summary_bytes_used, recalculate_used()));
6401 }
6402
6403 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6404 _refine_cte_cl->set_concurrent(concurrent);
6405 }
6406
6407 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6408 HeapRegion* hr = heap_region_containing(p);
6409 if (hr == NULL) {
6410 return false;
6411 } else {
6412 return hr->is_in(p);
6413 }
6414 }
6415
6416 // Methods for the mutator alloc region
6417
6418 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6419 bool force) {
6420 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6421 assert(!force || g1_policy()->can_expand_young_list(),
6422 "if force is true we should be able to expand the young list");
6423 bool young_list_full = g1_policy()->is_young_list_full();
6424 if (force || !young_list_full) {
6425 HeapRegion* new_alloc_region = new_region(word_size,
6426 false /* do_expand */);
6427 if (new_alloc_region != NULL) {
6428 set_region_short_lived_locked(new_alloc_region);
6429 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6430 return new_alloc_region;
6431 }
6432 }
6433 return NULL;
6434 }
6435
6436 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6437 size_t allocated_bytes) {
6438 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6439 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6440
6441 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6442 _summary_bytes_used += allocated_bytes;
6443 _hr_printer.retire(alloc_region);
6444 // We update the eden sizes here, when the region is retired,
6445 // instead of when it's allocated, since this is the point that its
6446 // used space has been recored in _summary_bytes_used.
6447 g1mm()->update_eden_size();
6448 }
6449
6450 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6451 bool force) {
6452 return _g1h->new_mutator_alloc_region(word_size, force);
6453 }
6454
6455 void G1CollectedHeap::set_par_threads() {
6456 // Don't change the number of workers. Use the value previously set
6457 // in the workgroup.
6458 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6459 uint n_workers = workers()->active_workers();
6460 assert(UseDynamicNumberOfGCThreads ||
6461 n_workers == workers()->total_workers(),
6462 "Otherwise should be using the total number of workers");
6463 if (n_workers == 0) {
6464 assert(false, "Should have been set in prior evacuation pause.");
6465 n_workers = ParallelGCThreads;
6466 workers()->set_active_workers(n_workers);
6467 }
6468 set_par_threads(n_workers);
6469 }
6470
6471 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6472 size_t allocated_bytes) {
6473 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6474 }
6475
6476 // Methods for the GC alloc regions
6477
6478 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6479 uint count,
6480 GCAllocPurpose ap) {
6481 assert(FreeList_lock->owned_by_self(), "pre-condition");
6482
6483 if (count < g1_policy()->max_regions(ap)) {
6484 HeapRegion* new_alloc_region = new_region(word_size,
6485 true /* do_expand */);
6486 if (new_alloc_region != NULL) {
6487 // We really only need to do this for old regions given that we
6488 // should never scan survivors. But it doesn't hurt to do it
6489 // for survivors too.
6490 new_alloc_region->set_saved_mark();
6491 if (ap == GCAllocForSurvived) {
6492 new_alloc_region->set_survivor();
6493 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6494 } else {
6495 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6496 }
6497 bool during_im = g1_policy()->during_initial_mark_pause();
6498 new_alloc_region->note_start_of_copying(during_im);
6499 return new_alloc_region;
6500 } else {
6501 g1_policy()->note_alloc_region_limit_reached(ap);
6502 }
6503 }
6504 return NULL;
6505 }
6506
6507 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6508 size_t allocated_bytes,
6509 GCAllocPurpose ap) {
6510 bool during_im = g1_policy()->during_initial_mark_pause();
6511 alloc_region->note_end_of_copying(during_im);
6512 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6513 if (ap == GCAllocForSurvived) {
6514 young_list()->add_survivor_region(alloc_region);
6515 } else {
6516 _old_set.add(alloc_region);
6517 }
6518 _hr_printer.retire(alloc_region);
6519 }
6520
6521 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6522 bool force) {
6523 assert(!force, "not supported for GC alloc regions");
6524 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6525 }
6526
6527 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6528 size_t allocated_bytes) {
6529 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6530 GCAllocForSurvived);
6531 }
6532
6533 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6534 bool force) {
6535 assert(!force, "not supported for GC alloc regions");
6536 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6537 }
6538
6539 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6540 size_t allocated_bytes) {
6541 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6542 GCAllocForTenured);
6543 }
6544 // Heap region set verification
6545
6546 class VerifyRegionListsClosure : public HeapRegionClosure {
6547 private:
6548 FreeRegionList* _free_list;
6549 OldRegionSet* _old_set;
6550 HumongousRegionSet* _humongous_set;
6551 uint _region_count;
6552
6553 public:
6554 VerifyRegionListsClosure(OldRegionSet* old_set,
6555 HumongousRegionSet* humongous_set,
6556 FreeRegionList* free_list) :
6557 _old_set(old_set), _humongous_set(humongous_set),
6558 _free_list(free_list), _region_count(0) { }
6559
6560 uint region_count() { return _region_count; }
6561
6562 bool doHeapRegion(HeapRegion* hr) {
6563 _region_count += 1;
6564
6565 if (hr->continuesHumongous()) {
6566 return false;
6567 }
6568
6569 if (hr->is_young()) {
6570 // TODO
6571 } else if (hr->startsHumongous()) {
6572 _humongous_set->verify_next_region(hr);
6573 } else if (hr->is_empty()) {
6574 _free_list->verify_next_region(hr);
6575 } else {
6576 _old_set->verify_next_region(hr);
6577 }
6578 return false;
6579 }
6580 };
6581
6582 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6583 HeapWord* bottom) {
6584 HeapWord* end = bottom + HeapRegion::GrainWords;
6585 MemRegion mr(bottom, end);
6586 assert(_g1_reserved.contains(mr), "invariant");
6587 // This might return NULL if the allocation fails
6588 return new HeapRegion(hrs_index, _bot_shared, mr);
6589 }
6590
6591 void G1CollectedHeap::verify_region_sets() {
6592 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6593
6594 // First, check the explicit lists.
6595 _free_list.verify();
6596 {
6597 // Given that a concurrent operation might be adding regions to
6598 // the secondary free list we have to take the lock before
6599 // verifying it.
6600 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6601 _secondary_free_list.verify();
6602 }
6603 _old_set.verify();
6604 _humongous_set.verify();
6605
6606 // If a concurrent region freeing operation is in progress it will
6607 // be difficult to correctly attributed any free regions we come
6608 // across to the correct free list given that they might belong to
6609 // one of several (free_list, secondary_free_list, any local lists,
6610 // etc.). So, if that's the case we will skip the rest of the
6611 // verification operation. Alternatively, waiting for the concurrent
6612 // operation to complete will have a non-trivial effect on the GC's
6613 // operation (no concurrent operation will last longer than the
6614 // interval between two calls to verification) and it might hide
6615 // any issues that we would like to catch during testing.
6616 if (free_regions_coming()) {
6617 return;
6618 }
6619
6620 // Make sure we append the secondary_free_list on the free_list so
6621 // that all free regions we will come across can be safely
6622 // attributed to the free_list.
6623 append_secondary_free_list_if_not_empty_with_lock();
6624
6625 // Finally, make sure that the region accounting in the lists is
6626 // consistent with what we see in the heap.
6627 _old_set.verify_start();
6628 _humongous_set.verify_start();
6629 _free_list.verify_start();
6630
6631 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6632 heap_region_iterate(&cl);
6633
6634 _old_set.verify_end();
6635 _humongous_set.verify_end();
6636 _free_list.verify_end();
6637 }
6638
6639 // Optimized nmethod scanning
6640
6641 class RegisterNMethodOopClosure: public OopClosure {
6642 G1CollectedHeap* _g1h;
6643 nmethod* _nm;
6644
6645 template <class T> void do_oop_work(T* p) {
6646 T heap_oop = oopDesc::load_heap_oop(p);
6647 if (!oopDesc::is_null(heap_oop)) {
6648 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6649 HeapRegion* hr = _g1h->heap_region_containing(obj);
6650 assert(!hr->isHumongous(), "code root in humongous region?");
6651
6652 // HeapRegion::add_strong_code_root() avoids adding duplicate
6653 // entries but having duplicates is OK since we "mark" nmethods
6654 // as visited when we scan the strong code root lists during the GC.
6655 hr->add_strong_code_root(_nm);
6656 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), "add failed?");
6657 }
6658 }
6659
6660 public:
6661 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6662 _g1h(g1h), _nm(nm) {}
6663
6664 void do_oop(oop* p) { do_oop_work(p); }
6665 void do_oop(narrowOop* p) { do_oop_work(p); }
6666 };
6667
6668 class UnregisterNMethodOopClosure: public OopClosure {
6669 G1CollectedHeap* _g1h;
6670 nmethod* _nm;
6671
6672 template <class T> void do_oop_work(T* p) {
6673 T heap_oop = oopDesc::load_heap_oop(p);
6674 if (!oopDesc::is_null(heap_oop)) {
6675 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6676 HeapRegion* hr = _g1h->heap_region_containing(obj);
6677 assert(!hr->isHumongous(), "code root in humongous region?");
6678 hr->remove_strong_code_root(_nm);
6679 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), "remove failed?");
6680 }
6681 }
6682
6683 public:
6684 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6685 _g1h(g1h), _nm(nm) {}
6686
6687 void do_oop(oop* p) { do_oop_work(p); }
6688 void do_oop(narrowOop* p) { do_oop_work(p); }
6689 };
6690
6691 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6692 CollectedHeap::register_nmethod(nm);
6693
6694 guarantee(nm != NULL, "sanity");
6695 RegisterNMethodOopClosure reg_cl(this, nm);
6696 nm->oops_do(®_cl);
6697 }
6698
6699 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6700 CollectedHeap::unregister_nmethod(nm);
6701
6702 guarantee(nm != NULL, "sanity");
6703 UnregisterNMethodOopClosure reg_cl(this, nm);
6704 nm->oops_do(®_cl, true);
6705 }
6706
6707 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6708 public:
6709 bool doHeapRegion(HeapRegion *hr) {
6710 assert(!hr->isHumongous(), "humongous region in collection set?");
6711 hr->migrate_strong_code_roots();
6712 return false;
6713 }
6714 };
6715
6716 void G1CollectedHeap::migrate_strong_code_roots() {
6717 MigrateCodeRootsHeapRegionClosure cl;
6718 double migrate_start = os::elapsedTime();
6719 collection_set_iterate(&cl);
6720 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6721 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6722 }
6723
6724 // Mark all the code roots that point into regions *not* in the
6725 // collection set.
6726 //
6727 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6728 // walking the the code roots lists of regions not in the collection
6729 // set. Suppose we have an nmethod (M) that points to objects in two
6730 // separate regions - one in the collection set (R1) and one not (R2).
6731 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6732 // nmethod M when walking the code roots for R1. When we come to scan
6733 // the code roots for R2, we would see that M is already marked and it
6734 // would be skipped and the objects in R2 that are referenced from M
6735 // would not be evacuated.
6736
6737 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6738
6739 class MarkStrongCodeRootOopClosure: public OopClosure {
6740 ConcurrentMark* _cm;
6741 HeapRegion* _hr;
6742 uint _worker_id;
6743
6744 template <class T> void do_oop_work(T* p) {
6745 T heap_oop = oopDesc::load_heap_oop(p);
6746 if (!oopDesc::is_null(heap_oop)) {
6747 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6748 // Only mark objects in the region (which is assumed
6749 // to be not in the collection set).
6750 if (_hr->is_in(obj)) {
6751 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6752 }
6753 }
6754 }
6755
6756 public:
6757 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6758 _cm(cm), _hr(hr), _worker_id(worker_id) {
6759 assert(!_hr->in_collection_set(), "sanity");
6760 }
6761
6762 void do_oop(narrowOop* p) { do_oop_work(p); }
6763 void do_oop(oop* p) { do_oop_work(p); }
6764 };
6765
6766 MarkStrongCodeRootOopClosure _oop_cl;
6767
6768 public:
6769 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6770 _oop_cl(cm, hr, worker_id) {}
6771
6772 void do_code_blob(CodeBlob* cb) {
6773 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6774 if (nm != NULL) {
6775 nm->oops_do(&_oop_cl);
6776 }
6777 }
6778 };
6779
6780 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6781 G1CollectedHeap* _g1h;
6782 uint _worker_id;
6783
6784 public:
6785 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6786 _g1h(g1h), _worker_id(worker_id) {}
6787
6788 bool doHeapRegion(HeapRegion *hr) {
6789 HeapRegionRemSet* hrrs = hr->rem_set();
6790 if (hr->isHumongous()) {
6791 // Code roots should never be attached to a humongous region
6792 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
6793 return false;
6794 }
6795
6796 if (hr->in_collection_set()) {
6797 // Don't mark code roots into regions in the collection set here.
6798 // They will be marked when we scan them.
6799 return false;
6800 }
6801
6802 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6803 hr->strong_code_roots_do(&cb_cl);
6804 return false;
6805 }
6806 };
6807
6808 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6809 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6810 if (G1CollectedHeap::use_parallel_gc_threads()) {
6811 heap_region_par_iterate_chunked(&cl,
6812 worker_id,
6813 workers()->active_workers(),
6814 HeapRegion::ParMarkRootClaimValue);
6815 } else {
6816 heap_region_iterate(&cl);
6817 }
6818 }
6819
6820 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6821 G1CollectedHeap* _g1h;
6822
6823 public:
6824 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6825 _g1h(g1h) {}
6826
6827 void do_code_blob(CodeBlob* cb) {
6828 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6829 if (nm == NULL) {
6830 return;
6831 }
6832
6833 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6834 _g1h->register_nmethod(nm);
6835 }
6836 }
6837 };
6838
6839 void G1CollectedHeap::rebuild_strong_code_roots() {
6840 RebuildStrongCodeRootClosure blob_cl(this);
6841 CodeCache::blobs_do(&blob_cl);
6842 }