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 aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1776 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1777 HeapRegion::GrainBytes);
1778 ergo_verbose2(ErgoHeapSizing,
1779 "expand the heap",
1780 ergo_format_byte("requested expansion amount")
1781 ergo_format_byte("attempted expansion amount"),
1782 expand_bytes, aligned_expand_bytes);
1783
1784 if (_g1_storage.uncommitted_size() == 0) {
1785 ergo_verbose0(ErgoHeapSizing,
1786 "did not expand the heap",
1787 ergo_format_reason("heap already fully expanded"));
1788 return false;
1789 }
1790
1791 // First commit the memory.
1792 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1793 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1794 if (successful) {
1795 // Then propagate this update to the necessary data structures.
1796 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1797 update_committed_space(old_end, new_end);
1798
1799 FreeRegionList expansion_list("Local Expansion List");
1800 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1801 assert(mr.start() == old_end, "post-condition");
1802 // mr might be a smaller region than what was requested if
1803 // expand_by() was unable to allocate the HeapRegion instances
1804 assert(mr.end() <= new_end, "post-condition");
1805
1806 size_t actual_expand_bytes = mr.byte_size();
1807 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1808 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1809 "post-condition");
1810 if (actual_expand_bytes < aligned_expand_bytes) {
1811 // We could not expand _hrs to the desired size. In this case we
1812 // need to shrink the committed space accordingly.
1813 assert(mr.end() < new_end, "invariant");
1814
1815 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1816 // First uncommit the memory.
1817 _g1_storage.shrink_by(diff_bytes);
1818 // Then propagate this update to the necessary data structures.
1819 update_committed_space(new_end, mr.end());
1820 }
1821 _free_list.add_as_tail(&expansion_list);
1822
1823 if (_hr_printer.is_active()) {
1824 HeapWord* curr = mr.start();
1825 while (curr < mr.end()) {
1826 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1827 _hr_printer.commit(curr, curr_end);
1828 curr = curr_end;
1829 }
1830 assert(curr == mr.end(), "post-condition");
1831 }
1832 g1_policy()->record_new_heap_size(n_regions());
1833 } else {
1834 ergo_verbose0(ErgoHeapSizing,
1835 "did not expand the heap",
1836 ergo_format_reason("heap expansion operation failed"));
1837 // The expansion of the virtual storage space was unsuccessful.
1838 // Let's see if it was because we ran out of swap.
1839 if (G1ExitOnExpansionFailure &&
1840 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1841 // We had head room...
1842 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1843 }
1844 }
1845 return successful;
1846 }
1847
1848 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1849 size_t aligned_shrink_bytes =
1850 ReservedSpace::page_align_size_down(shrink_bytes);
1851 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1852 HeapRegion::GrainBytes);
1853 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1854
1855 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1856 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1857 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1858
1859 ergo_verbose3(ErgoHeapSizing,
1860 "shrink the heap",
1861 ergo_format_byte("requested shrinking amount")
1862 ergo_format_byte("aligned shrinking amount")
1863 ergo_format_byte("attempted shrinking amount"),
1864 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1865 if (num_regions_removed > 0) {
1866 _g1_storage.shrink_by(shrunk_bytes);
1867 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1868
1869 if (_hr_printer.is_active()) {
1870 HeapWord* curr = old_end;
1871 while (curr > new_end) {
1872 HeapWord* curr_end = curr;
1873 curr -= HeapRegion::GrainWords;
1874 _hr_printer.uncommit(curr, curr_end);
1875 }
1876 }
1877
1878 _expansion_regions += num_regions_removed;
1879 update_committed_space(old_end, new_end);
1880 HeapRegionRemSet::shrink_heap(n_regions());
1881 g1_policy()->record_new_heap_size(n_regions());
1882 } else {
1883 ergo_verbose0(ErgoHeapSizing,
1884 "did not shrink the heap",
1885 ergo_format_reason("heap shrinking operation failed"));
1886 }
1887 }
1888
1889 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1890 verify_region_sets_optional();
1891
1892 // We should only reach here at the end of a Full GC which means we
1893 // should not not be holding to any GC alloc regions. The method
1894 // below will make sure of that and do any remaining clean up.
1895 abandon_gc_alloc_regions();
1896
1897 // Instead of tearing down / rebuilding the free lists here, we
1898 // could instead use the remove_all_pending() method on free_list to
1899 // remove only the ones that we need to remove.
1900 tear_down_region_sets(true /* free_list_only */);
1901 shrink_helper(shrink_bytes);
1902 rebuild_region_sets(true /* free_list_only */);
1903
1904 _hrs.verify_optional();
1905 verify_region_sets_optional();
1906 }
1907
1908 // Public methods.
1909
1910 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1911 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1912 #endif // _MSC_VER
1913
1914
1915 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1916 SharedHeap(policy_),
1917 _g1_policy(policy_),
1918 _dirty_card_queue_set(false),
1919 _into_cset_dirty_card_queue_set(false),
1920 _is_alive_closure_cm(this),
1921 _is_alive_closure_stw(this),
1922 _ref_processor_cm(NULL),
1923 _ref_processor_stw(NULL),
1924 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1925 _bot_shared(NULL),
1926 _evac_failure_scan_stack(NULL),
1927 _mark_in_progress(false),
1928 _cg1r(NULL), _summary_bytes_used(0),
1929 _g1mm(NULL),
1930 _refine_cte_cl(NULL),
1931 _full_collection(false),
1932 _free_list("Master Free List"),
1933 _secondary_free_list("Secondary Free List"),
1934 _old_set("Old Set"),
1935 _humongous_set("Master Humongous Set"),
1936 _free_regions_coming(false),
1937 _young_list(new YoungList(this)),
1938 _gc_time_stamp(0),
1939 _retained_old_gc_alloc_region(NULL),
1940 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1941 _old_plab_stats(OldPLABSize, PLABWeight),
1942 _expand_heap_after_alloc_failure(true),
1943 _surviving_young_words(NULL),
1944 _old_marking_cycles_started(0),
1945 _old_marking_cycles_completed(0),
1946 _concurrent_cycle_started(false),
1947 _in_cset_fast_test(NULL),
1948 _in_cset_fast_test_base(NULL),
1949 _dirty_cards_region_list(NULL),
1950 _worker_cset_start_region(NULL),
1951 _worker_cset_start_region_time_stamp(NULL),
1952 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1953 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1954 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1955 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1956
1957 _g1h = this;
1958 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1959 vm_exit_during_initialization("Failed necessary allocation.");
1960 }
1961
1962 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1963
1964 int n_queues = MAX2((int)ParallelGCThreads, 1);
1965 _task_queues = new RefToScanQueueSet(n_queues);
1966
1967 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1968 assert(n_rem_sets > 0, "Invariant.");
1969
1970 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1971 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1972 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1973
1974 for (int i = 0; i < n_queues; i++) {
1975 RefToScanQueue* q = new RefToScanQueue();
1976 q->initialize();
1977 _task_queues->register_queue(i, q);
1978 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1979 }
1980 clear_cset_start_regions();
1981
1982 // Initialize the G1EvacuationFailureALot counters and flags.
1983 NOT_PRODUCT(reset_evacuation_should_fail();)
1984
1985 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1986 }
1987
1988 jint G1CollectedHeap::initialize() {
1989 CollectedHeap::pre_initialize();
1990 os::enable_vtime();
1991
1992 G1Log::init();
1993
1994 // Necessary to satisfy locking discipline assertions.
1995
1996 MutexLocker x(Heap_lock);
1997
1998 // We have to initialize the printer before committing the heap, as
1999 // it will be used then.
2000 _hr_printer.set_active(G1PrintHeapRegions);
2001
2002 // While there are no constraints in the GC code that HeapWordSize
2003 // be any particular value, there are multiple other areas in the
2004 // system which believe this to be true (e.g. oop->object_size in some
2005 // cases incorrectly returns the size in wordSize units rather than
2006 // HeapWordSize).
2007 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2008
2009 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2010 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2011 size_t heap_alignment = collector_policy()->max_alignment();
2012
2013 // Ensure that the sizes are properly aligned.
2014 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2015 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2016 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2017
2018 _cg1r = new ConcurrentG1Refine(this);
2019
2020 // Reserve the maximum.
2021
2022 // When compressed oops are enabled, the preferred heap base
2023 // is calculated by subtracting the requested size from the
2024 // 32Gb boundary and using the result as the base address for
2025 // heap reservation. If the requested size is not aligned to
2026 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2027 // into the ReservedHeapSpace constructor) then the actual
2028 // base of the reserved heap may end up differing from the
2029 // address that was requested (i.e. the preferred heap base).
2030 // If this happens then we could end up using a non-optimal
2031 // compressed oops mode.
2032
2033 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2034 heap_alignment);
2035
2036 // It is important to do this in a way such that concurrent readers can't
2037 // temporarily think something is in the heap. (I've actually seen this
2038 // happen in asserts: DLD.)
2039 _reserved.set_word_size(0);
2040 _reserved.set_start((HeapWord*)heap_rs.base());
2041 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2042
2043 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2044
2045 // Create the gen rem set (and barrier set) for the entire reserved region.
2046 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2047 set_barrier_set(rem_set()->bs());
2048 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2049 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2050 return JNI_ENOMEM;
2051 }
2052
2053 // Also create a G1 rem set.
2054 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2055
2056 // Carve out the G1 part of the heap.
2057
2058 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2059 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2060 g1_rs.size()/HeapWordSize);
2061
2062 _g1_storage.initialize(g1_rs, 0);
2063 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2064 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2065 (HeapWord*) _g1_reserved.end());
2066 assert(_hrs.max_length() == _expansion_regions,
2067 err_msg("max length: %u expansion regions: %u",
2068 _hrs.max_length(), _expansion_regions));
2069
2070 // Do later initialization work for concurrent refinement.
2071 _cg1r->init();
2072
2073 // 6843694 - ensure that the maximum region index can fit
2074 // in the remembered set structures.
2075 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2076 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2077
2078 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2079 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2080 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2081 "too many cards per region");
2082
2083 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2084
2085 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2086 heap_word_size(init_byte_size));
2087
2088 _g1h = this;
2089
2090 _in_cset_fast_test_length = max_regions();
2091 _in_cset_fast_test_base =
2092 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2093
2094 // We're biasing _in_cset_fast_test to avoid subtracting the
2095 // beginning of the heap every time we want to index; basically
2096 // it's the same with what we do with the card table.
2097 _in_cset_fast_test = _in_cset_fast_test_base -
2098 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2099
2100 // Clear the _cset_fast_test bitmap in anticipation of adding
2101 // regions to the incremental collection set for the first
2102 // evacuation pause.
2103 clear_cset_fast_test();
2104
2105 // Create the ConcurrentMark data structure and thread.
2106 // (Must do this late, so that "max_regions" is defined.)
2107 _cm = new ConcurrentMark(this, heap_rs);
2108 if (_cm == NULL || !_cm->completed_initialization()) {
2109 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2110 return JNI_ENOMEM;
2111 }
2112 _cmThread = _cm->cmThread();
2113
2114 // Initialize the from_card cache structure of HeapRegionRemSet.
2115 HeapRegionRemSet::init_heap(max_regions());
2116
2117 // Now expand into the initial heap size.
2118 if (!expand(init_byte_size)) {
2119 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2120 return JNI_ENOMEM;
2121 }
2122
2123 // Perform any initialization actions delegated to the policy.
2124 g1_policy()->init();
2125
2126 _refine_cte_cl =
2127 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2128 g1_rem_set(),
2129 concurrent_g1_refine());
2130 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2131
2132 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2133 SATB_Q_FL_lock,
2134 G1SATBProcessCompletedThreshold,
2135 Shared_SATB_Q_lock);
2136
2137 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2138 DirtyCardQ_FL_lock,
2139 concurrent_g1_refine()->yellow_zone(),
2140 concurrent_g1_refine()->red_zone(),
2141 Shared_DirtyCardQ_lock);
2142
2143 if (G1DeferredRSUpdate) {
2144 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2145 DirtyCardQ_FL_lock,
2146 -1, // never trigger processing
2147 -1, // no limit on length
2148 Shared_DirtyCardQ_lock,
2149 &JavaThread::dirty_card_queue_set());
2150 }
2151
2152 // Initialize the card queue set used to hold cards containing
2153 // references into the collection set.
2154 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2155 DirtyCardQ_FL_lock,
2156 -1, // never trigger processing
2157 -1, // no limit on length
2158 Shared_DirtyCardQ_lock,
2159 &JavaThread::dirty_card_queue_set());
2160
2161 // In case we're keeping closure specialization stats, initialize those
2162 // counts and that mechanism.
2163 SpecializationStats::clear();
2164
2165 // Here we allocate the dummy full region that is required by the
2166 // G1AllocRegion class. If we don't pass an address in the reserved
2167 // space here, lots of asserts fire.
2168
2169 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2170 _g1_reserved.start());
2171 // We'll re-use the same region whether the alloc region will
2172 // require BOT updates or not and, if it doesn't, then a non-young
2173 // region will complain that it cannot support allocations without
2174 // BOT updates. So we'll tag the dummy region as young to avoid that.
2175 dummy_region->set_young();
2176 // Make sure it's full.
2177 dummy_region->set_top(dummy_region->end());
2178 G1AllocRegion::setup(this, dummy_region);
2179
2180 init_mutator_alloc_region();
2181
2182 // Do create of the monitoring and management support so that
2183 // values in the heap have been properly initialized.
2184 _g1mm = new G1MonitoringSupport(this);
2185
2186 return JNI_OK;
2187 }
2188
2189 void G1CollectedHeap::ref_processing_init() {
2190 // Reference processing in G1 currently works as follows:
2191 //
2192 // * There are two reference processor instances. One is
2193 // used to record and process discovered references
2194 // during concurrent marking; the other is used to
2195 // record and process references during STW pauses
2196 // (both full and incremental).
2197 // * Both ref processors need to 'span' the entire heap as
2198 // the regions in the collection set may be dotted around.
2199 //
2200 // * For the concurrent marking ref processor:
2201 // * Reference discovery is enabled at initial marking.
2202 // * Reference discovery is disabled and the discovered
2203 // references processed etc during remarking.
2204 // * Reference discovery is MT (see below).
2205 // * Reference discovery requires a barrier (see below).
2206 // * Reference processing may or may not be MT
2207 // (depending on the value of ParallelRefProcEnabled
2208 // and ParallelGCThreads).
2209 // * A full GC disables reference discovery by the CM
2210 // ref processor and abandons any entries on it's
2211 // discovered lists.
2212 //
2213 // * For the STW processor:
2214 // * Non MT discovery is enabled at the start of a full GC.
2215 // * Processing and enqueueing during a full GC is non-MT.
2216 // * During a full GC, references are processed after marking.
2217 //
2218 // * Discovery (may or may not be MT) is enabled at the start
2219 // of an incremental evacuation pause.
2220 // * References are processed near the end of a STW evacuation pause.
2221 // * For both types of GC:
2222 // * Discovery is atomic - i.e. not concurrent.
2223 // * Reference discovery will not need a barrier.
2224
2225 SharedHeap::ref_processing_init();
2226 MemRegion mr = reserved_region();
2227
2228 // Concurrent Mark ref processor
2229 _ref_processor_cm =
2230 new ReferenceProcessor(mr, // span
2231 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2232 // mt processing
2233 (int) ParallelGCThreads,
2234 // degree of mt processing
2235 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2236 // mt discovery
2237 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2238 // degree of mt discovery
2239 false,
2240 // Reference discovery is not atomic
2241 &_is_alive_closure_cm,
2242 // is alive closure
2243 // (for efficiency/performance)
2244 true);
2245 // Setting next fields of discovered
2246 // lists requires a barrier.
2247
2248 // STW ref processor
2249 _ref_processor_stw =
2250 new ReferenceProcessor(mr, // span
2251 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2252 // mt processing
2253 MAX2((int)ParallelGCThreads, 1),
2254 // degree of mt processing
2255 (ParallelGCThreads > 1),
2256 // mt discovery
2257 MAX2((int)ParallelGCThreads, 1),
2258 // degree of mt discovery
2259 true,
2260 // Reference discovery is atomic
2261 &_is_alive_closure_stw,
2262 // is alive closure
2263 // (for efficiency/performance)
2264 false);
2265 // Setting next fields of discovered
2266 // lists requires a barrier.
2267 }
2268
2269 size_t G1CollectedHeap::capacity() const {
2270 return _g1_committed.byte_size();
2271 }
2272
2273 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2274 assert(!hr->continuesHumongous(), "pre-condition");
2275 hr->reset_gc_time_stamp();
2276 if (hr->startsHumongous()) {
2277 uint first_index = hr->hrs_index() + 1;
2278 uint last_index = hr->last_hc_index();
2279 for (uint i = first_index; i < last_index; i += 1) {
2280 HeapRegion* chr = region_at(i);
2281 assert(chr->continuesHumongous(), "sanity");
2282 chr->reset_gc_time_stamp();
2283 }
2284 }
2285 }
2286
2287 #ifndef PRODUCT
2288 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2289 private:
2290 unsigned _gc_time_stamp;
2291 bool _failures;
2292
2293 public:
2294 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2295 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2296
2297 virtual bool doHeapRegion(HeapRegion* hr) {
2298 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2299 if (_gc_time_stamp != region_gc_time_stamp) {
2300 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2301 "expected %d", HR_FORMAT_PARAMS(hr),
2302 region_gc_time_stamp, _gc_time_stamp);
2303 _failures = true;
2304 }
2305 return false;
2306 }
2307
2308 bool failures() { return _failures; }
2309 };
2310
2311 void G1CollectedHeap::check_gc_time_stamps() {
2312 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2313 heap_region_iterate(&cl);
2314 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2315 }
2316 #endif // PRODUCT
2317
2318 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2319 DirtyCardQueue* into_cset_dcq,
2320 bool concurrent,
2321 int worker_i) {
2322 // Clean cards in the hot card cache
2323 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2324 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2325
2326 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2327 int n_completed_buffers = 0;
2328 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2329 n_completed_buffers++;
2330 }
2331 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2332 dcqs.clear_n_completed_buffers();
2333 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2334 }
2335
2336
2337 // Computes the sum of the storage used by the various regions.
2338
2339 size_t G1CollectedHeap::used() const {
2340 assert(Heap_lock->owner() != NULL,
2341 "Should be owned on this thread's behalf.");
2342 size_t result = _summary_bytes_used;
2343 // Read only once in case it is set to NULL concurrently
2344 HeapRegion* hr = _mutator_alloc_region.get();
2345 if (hr != NULL)
2346 result += hr->used();
2347 return result;
2348 }
2349
2350 size_t G1CollectedHeap::used_unlocked() const {
2351 size_t result = _summary_bytes_used;
2352 return result;
2353 }
2354
2355 class SumUsedClosure: public HeapRegionClosure {
2356 size_t _used;
2357 public:
2358 SumUsedClosure() : _used(0) {}
2359 bool doHeapRegion(HeapRegion* r) {
2360 if (!r->continuesHumongous()) {
2361 _used += r->used();
2362 }
2363 return false;
2364 }
2365 size_t result() { return _used; }
2366 };
2367
2368 size_t G1CollectedHeap::recalculate_used() const {
2369 SumUsedClosure blk;
2370 heap_region_iterate(&blk);
2371 return blk.result();
2372 }
2373
2374 size_t G1CollectedHeap::unsafe_max_alloc() {
2375 if (free_regions() > 0) return HeapRegion::GrainBytes;
2376 // otherwise, is there space in the current allocation region?
2377
2378 // We need to store the current allocation region in a local variable
2379 // here. The problem is that this method doesn't take any locks and
2380 // there may be other threads which overwrite the current allocation
2381 // region field. attempt_allocation(), for example, sets it to NULL
2382 // and this can happen *after* the NULL check here but before the call
2383 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2384 // to be a problem in the optimized build, since the two loads of the
2385 // current allocation region field are optimized away.
2386 HeapRegion* hr = _mutator_alloc_region.get();
2387 if (hr == NULL) {
2388 return 0;
2389 }
2390 return hr->free();
2391 }
2392
2393 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2394 switch (cause) {
2395 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2396 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2397 case GCCause::_g1_humongous_allocation: return true;
2398 default: return false;
2399 }
2400 }
2401
2402 #ifndef PRODUCT
2403 void G1CollectedHeap::allocate_dummy_regions() {
2404 // Let's fill up most of the region
2405 size_t word_size = HeapRegion::GrainWords - 1024;
2406 // And as a result the region we'll allocate will be humongous.
2407 guarantee(isHumongous(word_size), "sanity");
2408
2409 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2410 // Let's use the existing mechanism for the allocation
2411 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2412 if (dummy_obj != NULL) {
2413 MemRegion mr(dummy_obj, word_size);
2414 CollectedHeap::fill_with_object(mr);
2415 } else {
2416 // If we can't allocate once, we probably cannot allocate
2417 // again. Let's get out of the loop.
2418 break;
2419 }
2420 }
2421 }
2422 #endif // !PRODUCT
2423
2424 void G1CollectedHeap::increment_old_marking_cycles_started() {
2425 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2426 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2427 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2428 _old_marking_cycles_started, _old_marking_cycles_completed));
2429
2430 _old_marking_cycles_started++;
2431 }
2432
2433 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2434 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2435
2436 // We assume that if concurrent == true, then the caller is a
2437 // concurrent thread that was joined the Suspendible Thread
2438 // Set. If there's ever a cheap way to check this, we should add an
2439 // assert here.
2440
2441 // Given that this method is called at the end of a Full GC or of a
2442 // concurrent cycle, and those can be nested (i.e., a Full GC can
2443 // interrupt a concurrent cycle), the number of full collections
2444 // completed should be either one (in the case where there was no
2445 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2446 // behind the number of full collections started.
2447
2448 // This is the case for the inner caller, i.e. a Full GC.
2449 assert(concurrent ||
2450 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2451 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2452 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2453 "is inconsistent with _old_marking_cycles_completed = %u",
2454 _old_marking_cycles_started, _old_marking_cycles_completed));
2455
2456 // This is the case for the outer caller, i.e. the concurrent cycle.
2457 assert(!concurrent ||
2458 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2459 err_msg("for outer caller (concurrent cycle): "
2460 "_old_marking_cycles_started = %u "
2461 "is inconsistent with _old_marking_cycles_completed = %u",
2462 _old_marking_cycles_started, _old_marking_cycles_completed));
2463
2464 _old_marking_cycles_completed += 1;
2465
2466 // We need to clear the "in_progress" flag in the CM thread before
2467 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2468 // is set) so that if a waiter requests another System.gc() it doesn't
2469 // incorrectly see that a marking cycle is still in progress.
2470 if (concurrent) {
2471 _cmThread->clear_in_progress();
2472 }
2473
2474 // This notify_all() will ensure that a thread that called
2475 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2476 // and it's waiting for a full GC to finish will be woken up. It is
2477 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2478 FullGCCount_lock->notify_all();
2479 }
2480
2481 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2482 _concurrent_cycle_started = true;
2483 _gc_timer_cm->register_gc_start(start_time);
2484
2485 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2486 trace_heap_before_gc(_gc_tracer_cm);
2487 }
2488
2489 void G1CollectedHeap::register_concurrent_cycle_end() {
2490 if (_concurrent_cycle_started) {
2491 if (_cm->has_aborted()) {
2492 _gc_tracer_cm->report_concurrent_mode_failure();
2493 }
2494
2495 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2496 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2497
2498 _concurrent_cycle_started = false;
2499 }
2500 }
2501
2502 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2503 if (_concurrent_cycle_started) {
2504 trace_heap_after_gc(_gc_tracer_cm);
2505 }
2506 }
2507
2508 G1YCType G1CollectedHeap::yc_type() {
2509 bool is_young = g1_policy()->gcs_are_young();
2510 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2511 bool is_during_mark = mark_in_progress();
2512
2513 if (is_initial_mark) {
2514 return InitialMark;
2515 } else if (is_during_mark) {
2516 return DuringMark;
2517 } else if (is_young) {
2518 return Normal;
2519 } else {
2520 return Mixed;
2521 }
2522 }
2523
2524 void G1CollectedHeap::collect(GCCause::Cause cause) {
2525 assert_heap_not_locked();
2526
2527 unsigned int gc_count_before;
2528 unsigned int old_marking_count_before;
2529 bool retry_gc;
2530
2531 do {
2532 retry_gc = false;
2533
2534 {
2535 MutexLocker ml(Heap_lock);
2536
2537 // Read the GC count while holding the Heap_lock
2538 gc_count_before = total_collections();
2539 old_marking_count_before = _old_marking_cycles_started;
2540 }
2541
2542 if (should_do_concurrent_full_gc(cause)) {
2543 // Schedule an initial-mark evacuation pause that will start a
2544 // concurrent cycle. We're setting word_size to 0 which means that
2545 // we are not requesting a post-GC allocation.
2546 VM_G1IncCollectionPause op(gc_count_before,
2547 0, /* word_size */
2548 true, /* should_initiate_conc_mark */
2549 g1_policy()->max_pause_time_ms(),
2550 cause);
2551
2552 VMThread::execute(&op);
2553 if (!op.pause_succeeded()) {
2554 if (old_marking_count_before == _old_marking_cycles_started) {
2555 retry_gc = op.should_retry_gc();
2556 } else {
2557 // A Full GC happened while we were trying to schedule the
2558 // initial-mark GC. No point in starting a new cycle given
2559 // that the whole heap was collected anyway.
2560 }
2561
2562 if (retry_gc) {
2563 if (GC_locker::is_active_and_needs_gc()) {
2564 GC_locker::stall_until_clear();
2565 }
2566 }
2567 }
2568 } else {
2569 if (cause == GCCause::_gc_locker
2570 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2571
2572 // Schedule a standard evacuation pause. We're setting word_size
2573 // to 0 which means that we are not requesting a post-GC allocation.
2574 VM_G1IncCollectionPause op(gc_count_before,
2575 0, /* word_size */
2576 false, /* should_initiate_conc_mark */
2577 g1_policy()->max_pause_time_ms(),
2578 cause);
2579 VMThread::execute(&op);
2580 } else {
2581 // Schedule a Full GC.
2582 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2583 VMThread::execute(&op);
2584 }
2585 }
2586 } while (retry_gc);
2587 }
2588
2589 bool G1CollectedHeap::is_in(const void* p) const {
2590 if (_g1_committed.contains(p)) {
2591 // Given that we know that p is in the committed space,
2592 // heap_region_containing_raw() should successfully
2593 // return the containing region.
2594 HeapRegion* hr = heap_region_containing_raw(p);
2595 return hr->is_in(p);
2596 } else {
2597 return false;
2598 }
2599 }
2600
2601 // Iteration functions.
2602
2603 // Iterates an OopClosure over all ref-containing fields of objects
2604 // within a HeapRegion.
2605
2606 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2607 MemRegion _mr;
2608 ExtendedOopClosure* _cl;
2609 public:
2610 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2611 : _mr(mr), _cl(cl) {}
2612 bool doHeapRegion(HeapRegion* r) {
2613 if (!r->continuesHumongous()) {
2614 r->oop_iterate(_cl);
2615 }
2616 return false;
2617 }
2618 };
2619
2620 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2621 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2622 heap_region_iterate(&blk);
2623 }
2624
2625 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2626 IterateOopClosureRegionClosure blk(mr, cl);
2627 heap_region_iterate(&blk);
2628 }
2629
2630 // Iterates an ObjectClosure over all objects within a HeapRegion.
2631
2632 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2633 ObjectClosure* _cl;
2634 public:
2635 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2636 bool doHeapRegion(HeapRegion* r) {
2637 if (! r->continuesHumongous()) {
2638 r->object_iterate(_cl);
2639 }
2640 return false;
2641 }
2642 };
2643
2644 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2645 IterateObjectClosureRegionClosure blk(cl);
2646 heap_region_iterate(&blk);
2647 }
2648
2649 // Calls a SpaceClosure on a HeapRegion.
2650
2651 class SpaceClosureRegionClosure: public HeapRegionClosure {
2652 SpaceClosure* _cl;
2653 public:
2654 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2655 bool doHeapRegion(HeapRegion* r) {
2656 _cl->do_space(r);
2657 return false;
2658 }
2659 };
2660
2661 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2662 SpaceClosureRegionClosure blk(cl);
2663 heap_region_iterate(&blk);
2664 }
2665
2666 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2667 _hrs.iterate(cl);
2668 }
2669
2670 void
2671 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2672 uint worker_id,
2673 uint no_of_par_workers,
2674 jint claim_value) {
2675 const uint regions = n_regions();
2676 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2677 no_of_par_workers :
2678 1);
2679 assert(UseDynamicNumberOfGCThreads ||
2680 no_of_par_workers == workers()->total_workers(),
2681 "Non dynamic should use fixed number of workers");
2682 // try to spread out the starting points of the workers
2683 const HeapRegion* start_hr =
2684 start_region_for_worker(worker_id, no_of_par_workers);
2685 const uint start_index = start_hr->hrs_index();
2686
2687 // each worker will actually look at all regions
2688 for (uint count = 0; count < regions; ++count) {
2689 const uint index = (start_index + count) % regions;
2690 assert(0 <= index && index < regions, "sanity");
2691 HeapRegion* r = region_at(index);
2692 // we'll ignore "continues humongous" regions (we'll process them
2693 // when we come across their corresponding "start humongous"
2694 // region) and regions already claimed
2695 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2696 continue;
2697 }
2698 // OK, try to claim it
2699 if (r->claimHeapRegion(claim_value)) {
2700 // success!
2701 assert(!r->continuesHumongous(), "sanity");
2702 if (r->startsHumongous()) {
2703 // If the region is "starts humongous" we'll iterate over its
2704 // "continues humongous" first; in fact we'll do them
2705 // first. The order is important. In on case, calling the
2706 // closure on the "starts humongous" region might de-allocate
2707 // and clear all its "continues humongous" regions and, as a
2708 // result, we might end up processing them twice. So, we'll do
2709 // them first (notice: most closures will ignore them anyway) and
2710 // then we'll do the "starts humongous" region.
2711 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2712 HeapRegion* chr = region_at(ch_index);
2713
2714 // if the region has already been claimed or it's not
2715 // "continues humongous" we're done
2716 if (chr->claim_value() == claim_value ||
2717 !chr->continuesHumongous()) {
2718 break;
2719 }
2720
2721 // No one should have claimed it directly. We can given
2722 // that we claimed its "starts humongous" region.
2723 assert(chr->claim_value() != claim_value, "sanity");
2724 assert(chr->humongous_start_region() == r, "sanity");
2725
2726 if (chr->claimHeapRegion(claim_value)) {
2727 // we should always be able to claim it; no one else should
2728 // be trying to claim this region
2729
2730 bool res2 = cl->doHeapRegion(chr);
2731 assert(!res2, "Should not abort");
2732
2733 // Right now, this holds (i.e., no closure that actually
2734 // does something with "continues humongous" regions
2735 // clears them). We might have to weaken it in the future,
2736 // but let's leave these two asserts here for extra safety.
2737 assert(chr->continuesHumongous(), "should still be the case");
2738 assert(chr->humongous_start_region() == r, "sanity");
2739 } else {
2740 guarantee(false, "we should not reach here");
2741 }
2742 }
2743 }
2744
2745 assert(!r->continuesHumongous(), "sanity");
2746 bool res = cl->doHeapRegion(r);
2747 assert(!res, "Should not abort");
2748 }
2749 }
2750 }
2751
2752 class ResetClaimValuesClosure: public HeapRegionClosure {
2753 public:
2754 bool doHeapRegion(HeapRegion* r) {
2755 r->set_claim_value(HeapRegion::InitialClaimValue);
2756 return false;
2757 }
2758 };
2759
2760 void G1CollectedHeap::reset_heap_region_claim_values() {
2761 ResetClaimValuesClosure blk;
2762 heap_region_iterate(&blk);
2763 }
2764
2765 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2766 ResetClaimValuesClosure blk;
2767 collection_set_iterate(&blk);
2768 }
2769
2770 #ifdef ASSERT
2771 // This checks whether all regions in the heap have the correct claim
2772 // value. I also piggy-backed on this a check to ensure that the
2773 // humongous_start_region() information on "continues humongous"
2774 // regions is correct.
2775
2776 class CheckClaimValuesClosure : public HeapRegionClosure {
2777 private:
2778 jint _claim_value;
2779 uint _failures;
2780 HeapRegion* _sh_region;
2781
2782 public:
2783 CheckClaimValuesClosure(jint claim_value) :
2784 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2785 bool doHeapRegion(HeapRegion* r) {
2786 if (r->claim_value() != _claim_value) {
2787 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2788 "claim value = %d, should be %d",
2789 HR_FORMAT_PARAMS(r),
2790 r->claim_value(), _claim_value);
2791 ++_failures;
2792 }
2793 if (!r->isHumongous()) {
2794 _sh_region = NULL;
2795 } else if (r->startsHumongous()) {
2796 _sh_region = r;
2797 } else if (r->continuesHumongous()) {
2798 if (r->humongous_start_region() != _sh_region) {
2799 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2800 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2801 HR_FORMAT_PARAMS(r),
2802 r->humongous_start_region(),
2803 _sh_region);
2804 ++_failures;
2805 }
2806 }
2807 return false;
2808 }
2809 uint failures() { return _failures; }
2810 };
2811
2812 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2813 CheckClaimValuesClosure cl(claim_value);
2814 heap_region_iterate(&cl);
2815 return cl.failures() == 0;
2816 }
2817
2818 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2819 private:
2820 jint _claim_value;
2821 uint _failures;
2822
2823 public:
2824 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2825 _claim_value(claim_value), _failures(0) { }
2826
2827 uint failures() { return _failures; }
2828
2829 bool doHeapRegion(HeapRegion* hr) {
2830 assert(hr->in_collection_set(), "how?");
2831 assert(!hr->isHumongous(), "H-region in CSet");
2832 if (hr->claim_value() != _claim_value) {
2833 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2834 "claim value = %d, should be %d",
2835 HR_FORMAT_PARAMS(hr),
2836 hr->claim_value(), _claim_value);
2837 _failures += 1;
2838 }
2839 return false;
2840 }
2841 };
2842
2843 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2844 CheckClaimValuesInCSetHRClosure cl(claim_value);
2845 collection_set_iterate(&cl);
2846 return cl.failures() == 0;
2847 }
2848 #endif // ASSERT
2849
2850 // Clear the cached CSet starting regions and (more importantly)
2851 // the time stamps. Called when we reset the GC time stamp.
2852 void G1CollectedHeap::clear_cset_start_regions() {
2853 assert(_worker_cset_start_region != NULL, "sanity");
2854 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2855
2856 int n_queues = MAX2((int)ParallelGCThreads, 1);
2857 for (int i = 0; i < n_queues; i++) {
2858 _worker_cset_start_region[i] = NULL;
2859 _worker_cset_start_region_time_stamp[i] = 0;
2860 }
2861 }
2862
2863 // Given the id of a worker, obtain or calculate a suitable
2864 // starting region for iterating over the current collection set.
2865 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2866 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2867
2868 HeapRegion* result = NULL;
2869 unsigned gc_time_stamp = get_gc_time_stamp();
2870
2871 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2872 // Cached starting region for current worker was set
2873 // during the current pause - so it's valid.
2874 // Note: the cached starting heap region may be NULL
2875 // (when the collection set is empty).
2876 result = _worker_cset_start_region[worker_i];
2877 assert(result == NULL || result->in_collection_set(), "sanity");
2878 return result;
2879 }
2880
2881 // The cached entry was not valid so let's calculate
2882 // a suitable starting heap region for this worker.
2883
2884 // We want the parallel threads to start their collection
2885 // set iteration at different collection set regions to
2886 // avoid contention.
2887 // If we have:
2888 // n collection set regions
2889 // p threads
2890 // Then thread t will start at region floor ((t * n) / p)
2891
2892 result = g1_policy()->collection_set();
2893 if (G1CollectedHeap::use_parallel_gc_threads()) {
2894 uint cs_size = g1_policy()->cset_region_length();
2895 uint active_workers = workers()->active_workers();
2896 assert(UseDynamicNumberOfGCThreads ||
2897 active_workers == workers()->total_workers(),
2898 "Unless dynamic should use total workers");
2899
2900 uint end_ind = (cs_size * worker_i) / active_workers;
2901 uint start_ind = 0;
2902
2903 if (worker_i > 0 &&
2904 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2905 // Previous workers starting region is valid
2906 // so let's iterate from there
2907 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2908 result = _worker_cset_start_region[worker_i - 1];
2909 }
2910
2911 for (uint i = start_ind; i < end_ind; i++) {
2912 result = result->next_in_collection_set();
2913 }
2914 }
2915
2916 // Note: the calculated starting heap region may be NULL
2917 // (when the collection set is empty).
2918 assert(result == NULL || result->in_collection_set(), "sanity");
2919 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2920 "should be updated only once per pause");
2921 _worker_cset_start_region[worker_i] = result;
2922 OrderAccess::storestore();
2923 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2924 return result;
2925 }
2926
2927 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2928 uint no_of_par_workers) {
2929 uint worker_num =
2930 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2931 assert(UseDynamicNumberOfGCThreads ||
2932 no_of_par_workers == workers()->total_workers(),
2933 "Non dynamic should use fixed number of workers");
2934 const uint start_index = n_regions() * worker_i / worker_num;
2935 return region_at(start_index);
2936 }
2937
2938 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2939 HeapRegion* r = g1_policy()->collection_set();
2940 while (r != NULL) {
2941 HeapRegion* next = r->next_in_collection_set();
2942 if (cl->doHeapRegion(r)) {
2943 cl->incomplete();
2944 return;
2945 }
2946 r = next;
2947 }
2948 }
2949
2950 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2951 HeapRegionClosure *cl) {
2952 if (r == NULL) {
2953 // The CSet is empty so there's nothing to do.
2954 return;
2955 }
2956
2957 assert(r->in_collection_set(),
2958 "Start region must be a member of the collection set.");
2959 HeapRegion* cur = r;
2960 while (cur != NULL) {
2961 HeapRegion* next = cur->next_in_collection_set();
2962 if (cl->doHeapRegion(cur) && false) {
2963 cl->incomplete();
2964 return;
2965 }
2966 cur = next;
2967 }
2968 cur = g1_policy()->collection_set();
2969 while (cur != r) {
2970 HeapRegion* next = cur->next_in_collection_set();
2971 if (cl->doHeapRegion(cur) && false) {
2972 cl->incomplete();
2973 return;
2974 }
2975 cur = next;
2976 }
2977 }
2978
2979 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2980 return n_regions() > 0 ? region_at(0) : NULL;
2981 }
2982
2983
2984 Space* G1CollectedHeap::space_containing(const void* addr) const {
2985 Space* res = heap_region_containing(addr);
2986 return res;
2987 }
2988
2989 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2990 Space* sp = space_containing(addr);
2991 if (sp != NULL) {
2992 return sp->block_start(addr);
2993 }
2994 return NULL;
2995 }
2996
2997 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2998 Space* sp = space_containing(addr);
2999 assert(sp != NULL, "block_size of address outside of heap");
3000 return sp->block_size(addr);
3001 }
3002
3003 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3004 Space* sp = space_containing(addr);
3005 return sp->block_is_obj(addr);
3006 }
3007
3008 bool G1CollectedHeap::supports_tlab_allocation() const {
3009 return true;
3010 }
3011
3012 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3013 return HeapRegion::GrainBytes;
3014 }
3015
3016 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3017 // Return the remaining space in the cur alloc region, but not less than
3018 // the min TLAB size.
3019
3020 // Also, this value can be at most the humongous object threshold,
3021 // since we can't allow tlabs to grow big enough to accommodate
3022 // humongous objects.
3023
3024 HeapRegion* hr = _mutator_alloc_region.get();
3025 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3026 if (hr == NULL) {
3027 return max_tlab_size;
3028 } else {
3029 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3030 }
3031 }
3032
3033 size_t G1CollectedHeap::max_capacity() const {
3034 return _g1_reserved.byte_size();
3035 }
3036
3037 jlong G1CollectedHeap::millis_since_last_gc() {
3038 // assert(false, "NYI");
3039 return 0;
3040 }
3041
3042 void G1CollectedHeap::prepare_for_verify() {
3043 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3044 ensure_parsability(false);
3045 }
3046 g1_rem_set()->prepare_for_verify();
3047 }
3048
3049 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3050 VerifyOption vo) {
3051 switch (vo) {
3052 case VerifyOption_G1UsePrevMarking:
3053 return hr->obj_allocated_since_prev_marking(obj);
3054 case VerifyOption_G1UseNextMarking:
3055 return hr->obj_allocated_since_next_marking(obj);
3056 case VerifyOption_G1UseMarkWord:
3057 return false;
3058 default:
3059 ShouldNotReachHere();
3060 }
3061 return false; // keep some compilers happy
3062 }
3063
3064 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3065 switch (vo) {
3066 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3067 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3068 case VerifyOption_G1UseMarkWord: return NULL;
3069 default: ShouldNotReachHere();
3070 }
3071 return NULL; // keep some compilers happy
3072 }
3073
3074 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3075 switch (vo) {
3076 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3077 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3078 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3079 default: ShouldNotReachHere();
3080 }
3081 return false; // keep some compilers happy
3082 }
3083
3084 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3085 switch (vo) {
3086 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3087 case VerifyOption_G1UseNextMarking: return "NTAMS";
3088 case VerifyOption_G1UseMarkWord: return "NONE";
3089 default: ShouldNotReachHere();
3090 }
3091 return NULL; // keep some compilers happy
3092 }
3093
3094 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3095 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3096 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3097 // we can change this closure to extend the simpler OopClosure.
3098 class VerifyRootsClosure: public OopsInGenClosure {
3099 private:
3100 G1CollectedHeap* _g1h;
3101 VerifyOption _vo;
3102 bool _failures;
3103 public:
3104 // _vo == UsePrevMarking -> use "prev" marking information,
3105 // _vo == UseNextMarking -> use "next" marking information,
3106 // _vo == UseMarkWord -> use mark word from object header.
3107 VerifyRootsClosure(VerifyOption vo) :
3108 _g1h(G1CollectedHeap::heap()),
3109 _vo(vo),
3110 _failures(false) { }
3111
3112 bool failures() { return _failures; }
3113
3114 template <class T> void do_oop_nv(T* p) {
3115 T heap_oop = oopDesc::load_heap_oop(p);
3116 if (!oopDesc::is_null(heap_oop)) {
3117 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3118 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3119 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3120 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3121 if (_vo == VerifyOption_G1UseMarkWord) {
3122 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3123 }
3124 obj->print_on(gclog_or_tty);
3125 _failures = true;
3126 }
3127 }
3128 }
3129
3130 void do_oop(oop* p) { do_oop_nv(p); }
3131 void do_oop(narrowOop* p) { do_oop_nv(p); }
3132 };
3133
3134 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3135 G1CollectedHeap* _g1h;
3136 OopClosure* _root_cl;
3137 nmethod* _nm;
3138 VerifyOption _vo;
3139 bool _failures;
3140
3141 template <class T> void do_oop_work(T* p) {
3142 // First verify that this root is live
3143 _root_cl->do_oop(p);
3144
3145 if (!G1VerifyHeapRegionCodeRoots) {
3146 // We're not verifying the code roots attached to heap region.
3147 return;
3148 }
3149
3150 // Don't check the code roots during marking verification in a full GC
3151 if (_vo == VerifyOption_G1UseMarkWord) {
3152 return;
3153 }
3154
3155 // Now verify that the current nmethod (which contains p) is
3156 // in the code root list of the heap region containing the
3157 // object referenced by p.
3158
3159 T heap_oop = oopDesc::load_heap_oop(p);
3160 if (!oopDesc::is_null(heap_oop)) {
3161 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3162
3163 // Now fetch the region containing the object
3164 HeapRegion* hr = _g1h->heap_region_containing(obj);
3165 HeapRegionRemSet* hrrs = hr->rem_set();
3166 // Verify that the strong code root list for this region
3167 // contains the nmethod
3168 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3169 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3170 "from nmethod "PTR_FORMAT" not in strong "
3171 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3172 p, _nm, hr->bottom(), hr->end());
3173 _failures = true;
3174 }
3175 }
3176 }
3177
3178 public:
3179 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3180 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3181
3182 void do_oop(oop* p) { do_oop_work(p); }
3183 void do_oop(narrowOop* p) { do_oop_work(p); }
3184
3185 void set_nmethod(nmethod* nm) { _nm = nm; }
3186 bool failures() { return _failures; }
3187 };
3188
3189 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3190 G1VerifyCodeRootOopClosure* _oop_cl;
3191
3192 public:
3193 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3194 _oop_cl(oop_cl) {}
3195
3196 void do_code_blob(CodeBlob* cb) {
3197 nmethod* nm = cb->as_nmethod_or_null();
3198 if (nm != NULL) {
3199 _oop_cl->set_nmethod(nm);
3200 nm->oops_do(_oop_cl);
3201 }
3202 }
3203 };
3204
3205 class YoungRefCounterClosure : public OopClosure {
3206 G1CollectedHeap* _g1h;
3207 int _count;
3208 public:
3209 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3210 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3211 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3212
3213 int count() { return _count; }
3214 void reset_count() { _count = 0; };
3215 };
3216
3217 class VerifyKlassClosure: public KlassClosure {
3218 YoungRefCounterClosure _young_ref_counter_closure;
3219 OopClosure *_oop_closure;
3220 public:
3221 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3222 void do_klass(Klass* k) {
3223 k->oops_do(_oop_closure);
3224
3225 _young_ref_counter_closure.reset_count();
3226 k->oops_do(&_young_ref_counter_closure);
3227 if (_young_ref_counter_closure.count() > 0) {
3228 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3229 }
3230 }
3231 };
3232
3233 class VerifyLivenessOopClosure: public OopClosure {
3234 G1CollectedHeap* _g1h;
3235 VerifyOption _vo;
3236 public:
3237 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3238 _g1h(g1h), _vo(vo)
3239 { }
3240 void do_oop(narrowOop *p) { do_oop_work(p); }
3241 void do_oop( oop *p) { do_oop_work(p); }
3242
3243 template <class T> void do_oop_work(T *p) {
3244 oop obj = oopDesc::load_decode_heap_oop(p);
3245 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3246 "Dead object referenced by a not dead object");
3247 }
3248 };
3249
3250 class VerifyObjsInRegionClosure: public ObjectClosure {
3251 private:
3252 G1CollectedHeap* _g1h;
3253 size_t _live_bytes;
3254 HeapRegion *_hr;
3255 VerifyOption _vo;
3256 public:
3257 // _vo == UsePrevMarking -> use "prev" marking information,
3258 // _vo == UseNextMarking -> use "next" marking information,
3259 // _vo == UseMarkWord -> use mark word from object header.
3260 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3261 : _live_bytes(0), _hr(hr), _vo(vo) {
3262 _g1h = G1CollectedHeap::heap();
3263 }
3264 void do_object(oop o) {
3265 VerifyLivenessOopClosure isLive(_g1h, _vo);
3266 assert(o != NULL, "Huh?");
3267 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3268 // If the object is alive according to the mark word,
3269 // then verify that the marking information agrees.
3270 // Note we can't verify the contra-positive of the
3271 // above: if the object is dead (according to the mark
3272 // word), it may not be marked, or may have been marked
3273 // but has since became dead, or may have been allocated
3274 // since the last marking.
3275 if (_vo == VerifyOption_G1UseMarkWord) {
3276 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3277 }
3278
3279 o->oop_iterate_no_header(&isLive);
3280 if (!_hr->obj_allocated_since_prev_marking(o)) {
3281 size_t obj_size = o->size(); // Make sure we don't overflow
3282 _live_bytes += (obj_size * HeapWordSize);
3283 }
3284 }
3285 }
3286 size_t live_bytes() { return _live_bytes; }
3287 };
3288
3289 class PrintObjsInRegionClosure : public ObjectClosure {
3290 HeapRegion *_hr;
3291 G1CollectedHeap *_g1;
3292 public:
3293 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3294 _g1 = G1CollectedHeap::heap();
3295 };
3296
3297 void do_object(oop o) {
3298 if (o != NULL) {
3299 HeapWord *start = (HeapWord *) o;
3300 size_t word_sz = o->size();
3301 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3302 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3303 (void*) o, word_sz,
3304 _g1->isMarkedPrev(o),
3305 _g1->isMarkedNext(o),
3306 _hr->obj_allocated_since_prev_marking(o));
3307 HeapWord *end = start + word_sz;
3308 HeapWord *cur;
3309 int *val;
3310 for (cur = start; cur < end; cur++) {
3311 val = (int *) cur;
3312 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3313 }
3314 }
3315 }
3316 };
3317
3318 class VerifyRegionClosure: public HeapRegionClosure {
3319 private:
3320 bool _par;
3321 VerifyOption _vo;
3322 bool _failures;
3323 public:
3324 // _vo == UsePrevMarking -> use "prev" marking information,
3325 // _vo == UseNextMarking -> use "next" marking information,
3326 // _vo == UseMarkWord -> use mark word from object header.
3327 VerifyRegionClosure(bool par, VerifyOption vo)
3328 : _par(par),
3329 _vo(vo),
3330 _failures(false) {}
3331
3332 bool failures() {
3333 return _failures;
3334 }
3335
3336 bool doHeapRegion(HeapRegion* r) {
3337 if (!r->continuesHumongous()) {
3338 bool failures = false;
3339 r->verify(_vo, &failures);
3340 if (failures) {
3341 _failures = true;
3342 } else {
3343 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3344 r->object_iterate(¬_dead_yet_cl);
3345 if (_vo != VerifyOption_G1UseNextMarking) {
3346 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3347 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3348 "max_live_bytes "SIZE_FORMAT" "
3349 "< calculated "SIZE_FORMAT,
3350 r->bottom(), r->end(),
3351 r->max_live_bytes(),
3352 not_dead_yet_cl.live_bytes());
3353 _failures = true;
3354 }
3355 } else {
3356 // When vo == UseNextMarking we cannot currently do a sanity
3357 // check on the live bytes as the calculation has not been
3358 // finalized yet.
3359 }
3360 }
3361 }
3362 return false; // stop the region iteration if we hit a failure
3363 }
3364 };
3365
3366 // This is the task used for parallel verification of the heap regions
3367
3368 class G1ParVerifyTask: public AbstractGangTask {
3369 private:
3370 G1CollectedHeap* _g1h;
3371 VerifyOption _vo;
3372 bool _failures;
3373
3374 public:
3375 // _vo == UsePrevMarking -> use "prev" marking information,
3376 // _vo == UseNextMarking -> use "next" marking information,
3377 // _vo == UseMarkWord -> use mark word from object header.
3378 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3379 AbstractGangTask("Parallel verify task"),
3380 _g1h(g1h),
3381 _vo(vo),
3382 _failures(false) { }
3383
3384 bool failures() {
3385 return _failures;
3386 }
3387
3388 void work(uint worker_id) {
3389 HandleMark hm;
3390 VerifyRegionClosure blk(true, _vo);
3391 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3392 _g1h->workers()->active_workers(),
3393 HeapRegion::ParVerifyClaimValue);
3394 if (blk.failures()) {
3395 _failures = true;
3396 }
3397 }
3398 };
3399
3400 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3401 if (SafepointSynchronize::is_at_safepoint()) {
3402 assert(Thread::current()->is_VM_thread(),
3403 "Expected to be executed serially by the VM thread at this point");
3404
3405 if (!silent) { gclog_or_tty->print("Roots "); }
3406 VerifyRootsClosure rootsCl(vo);
3407 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3408 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3409 VerifyKlassClosure klassCl(this, &rootsCl);
3410
3411 // We apply the relevant closures to all the oops in the
3412 // system dictionary, the string table and the code cache.
3413 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3414
3415 // Need cleared claim bits for the strong roots processing
3416 ClassLoaderDataGraph::clear_claimed_marks();
3417
3418 process_strong_roots(true, // activate StrongRootsScope
3419 false, // we set "is scavenging" to false,
3420 // so we don't reset the dirty cards.
3421 ScanningOption(so), // roots scanning options
3422 &rootsCl,
3423 &blobsCl,
3424 &klassCl
3425 );
3426
3427 bool failures = rootsCl.failures() || codeRootsCl.failures();
3428
3429 if (vo != VerifyOption_G1UseMarkWord) {
3430 // If we're verifying during a full GC then the region sets
3431 // will have been torn down at the start of the GC. Therefore
3432 // verifying the region sets will fail. So we only verify
3433 // the region sets when not in a full GC.
3434 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3435 verify_region_sets();
3436 }
3437
3438 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3439 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3440 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3441 "sanity check");
3442
3443 G1ParVerifyTask task(this, vo);
3444 assert(UseDynamicNumberOfGCThreads ||
3445 workers()->active_workers() == workers()->total_workers(),
3446 "If not dynamic should be using all the workers");
3447 int n_workers = workers()->active_workers();
3448 set_par_threads(n_workers);
3449 workers()->run_task(&task);
3450 set_par_threads(0);
3451 if (task.failures()) {
3452 failures = true;
3453 }
3454
3455 // Checks that the expected amount of parallel work was done.
3456 // The implication is that n_workers is > 0.
3457 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3458 "sanity check");
3459
3460 reset_heap_region_claim_values();
3461
3462 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3463 "sanity check");
3464 } else {
3465 VerifyRegionClosure blk(false, vo);
3466 heap_region_iterate(&blk);
3467 if (blk.failures()) {
3468 failures = true;
3469 }
3470 }
3471 if (!silent) gclog_or_tty->print("RemSet ");
3472 rem_set()->verify();
3473
3474 if (failures) {
3475 gclog_or_tty->print_cr("Heap:");
3476 // It helps to have the per-region information in the output to
3477 // help us track down what went wrong. This is why we call
3478 // print_extended_on() instead of print_on().
3479 print_extended_on(gclog_or_tty);
3480 gclog_or_tty->print_cr("");
3481 #ifndef PRODUCT
3482 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3483 concurrent_mark()->print_reachable("at-verification-failure",
3484 vo, false /* all */);
3485 }
3486 #endif
3487 gclog_or_tty->flush();
3488 }
3489 guarantee(!failures, "there should not have been any failures");
3490 } else {
3491 if (!silent)
3492 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3493 }
3494 }
3495
3496 void G1CollectedHeap::verify(bool silent) {
3497 verify(silent, VerifyOption_G1UsePrevMarking);
3498 }
3499
3500 double G1CollectedHeap::verify(bool guard, const char* msg) {
3501 double verify_time_ms = 0.0;
3502
3503 if (guard && total_collections() >= VerifyGCStartAt) {
3504 double verify_start = os::elapsedTime();
3505 HandleMark hm; // Discard invalid handles created during verification
3506 prepare_for_verify();
3507 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3508 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3509 }
3510
3511 return verify_time_ms;
3512 }
3513
3514 void G1CollectedHeap::verify_before_gc() {
3515 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3516 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3517 }
3518
3519 void G1CollectedHeap::verify_after_gc() {
3520 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3521 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3522 }
3523
3524 class PrintRegionClosure: public HeapRegionClosure {
3525 outputStream* _st;
3526 public:
3527 PrintRegionClosure(outputStream* st) : _st(st) {}
3528 bool doHeapRegion(HeapRegion* r) {
3529 r->print_on(_st);
3530 return false;
3531 }
3532 };
3533
3534 void G1CollectedHeap::print_on(outputStream* st) const {
3535 st->print(" %-20s", "garbage-first heap");
3536 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3537 capacity()/K, used_unlocked()/K);
3538 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3539 _g1_storage.low_boundary(),
3540 _g1_storage.high(),
3541 _g1_storage.high_boundary());
3542 st->cr();
3543 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3544 uint young_regions = _young_list->length();
3545 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3546 (size_t) young_regions * HeapRegion::GrainBytes / K);
3547 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3548 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3549 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3550 st->cr();
3551 MetaspaceAux::print_on(st);
3552 }
3553
3554 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3555 print_on(st);
3556
3557 // Print the per-region information.
3558 st->cr();
3559 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3560 "HS=humongous(starts), HC=humongous(continues), "
3561 "CS=collection set, F=free, TS=gc time stamp, "
3562 "PTAMS=previous top-at-mark-start, "
3563 "NTAMS=next top-at-mark-start)");
3564 PrintRegionClosure blk(st);
3565 heap_region_iterate(&blk);
3566 }
3567
3568 void G1CollectedHeap::print_on_error(outputStream* st) const {
3569 this->CollectedHeap::print_on_error(st);
3570
3571 if (_cm != NULL) {
3572 st->cr();
3573 _cm->print_on_error(st);
3574 }
3575 }
3576
3577 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3578 if (G1CollectedHeap::use_parallel_gc_threads()) {
3579 workers()->print_worker_threads_on(st);
3580 }
3581 _cmThread->print_on(st);
3582 st->cr();
3583 _cm->print_worker_threads_on(st);
3584 _cg1r->print_worker_threads_on(st);
3585 }
3586
3587 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3588 if (G1CollectedHeap::use_parallel_gc_threads()) {
3589 workers()->threads_do(tc);
3590 }
3591 tc->do_thread(_cmThread);
3592 _cg1r->threads_do(tc);
3593 }
3594
3595 void G1CollectedHeap::print_tracing_info() const {
3596 // We'll overload this to mean "trace GC pause statistics."
3597 if (TraceGen0Time || TraceGen1Time) {
3598 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3599 // to that.
3600 g1_policy()->print_tracing_info();
3601 }
3602 if (G1SummarizeRSetStats) {
3603 g1_rem_set()->print_summary_info();
3604 }
3605 if (G1SummarizeConcMark) {
3606 concurrent_mark()->print_summary_info();
3607 }
3608 g1_policy()->print_yg_surv_rate_info();
3609 SpecializationStats::print();
3610 }
3611
3612 #ifndef PRODUCT
3613 // Helpful for debugging RSet issues.
3614
3615 class PrintRSetsClosure : public HeapRegionClosure {
3616 private:
3617 const char* _msg;
3618 size_t _occupied_sum;
3619
3620 public:
3621 bool doHeapRegion(HeapRegion* r) {
3622 HeapRegionRemSet* hrrs = r->rem_set();
3623 size_t occupied = hrrs->occupied();
3624 _occupied_sum += occupied;
3625
3626 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3627 HR_FORMAT_PARAMS(r));
3628 if (occupied == 0) {
3629 gclog_or_tty->print_cr(" RSet is empty");
3630 } else {
3631 hrrs->print();
3632 }
3633 gclog_or_tty->print_cr("----------");
3634 return false;
3635 }
3636
3637 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3638 gclog_or_tty->cr();
3639 gclog_or_tty->print_cr("========================================");
3640 gclog_or_tty->print_cr(msg);
3641 gclog_or_tty->cr();
3642 }
3643
3644 ~PrintRSetsClosure() {
3645 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3646 gclog_or_tty->print_cr("========================================");
3647 gclog_or_tty->cr();
3648 }
3649 };
3650
3651 void G1CollectedHeap::print_cset_rsets() {
3652 PrintRSetsClosure cl("Printing CSet RSets");
3653 collection_set_iterate(&cl);
3654 }
3655
3656 void G1CollectedHeap::print_all_rsets() {
3657 PrintRSetsClosure cl("Printing All RSets");;
3658 heap_region_iterate(&cl);
3659 }
3660 #endif // PRODUCT
3661
3662 G1CollectedHeap* G1CollectedHeap::heap() {
3663 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3664 "not a garbage-first heap");
3665 return _g1h;
3666 }
3667
3668 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3669 // always_do_update_barrier = false;
3670 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3671 // Fill TLAB's and such
3672 ensure_parsability(true);
3673
3674 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3675 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3676 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3677 }
3678 }
3679
3680 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3681
3682 if (G1SummarizeRSetStats &&
3683 (G1SummarizeRSetStatsPeriod > 0) &&
3684 // we are at the end of the GC. Total collections has already been increased.
3685 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3686 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3687 }
3688
3689 // FIXME: what is this about?
3690 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3691 // is set.
3692 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3693 "derived pointer present"));
3694 // always_do_update_barrier = true;
3695
3696 // We have just completed a GC. Update the soft reference
3697 // policy with the new heap occupancy
3698 Universe::update_heap_info_at_gc();
3699 }
3700
3701 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3702 unsigned int gc_count_before,
3703 bool* succeeded,
3704 GCCause::Cause gc_cause) {
3705 assert_heap_not_locked_and_not_at_safepoint();
3706 g1_policy()->record_stop_world_start();
3707 VM_G1IncCollectionPause op(gc_count_before,
3708 word_size,
3709 false, /* should_initiate_conc_mark */
3710 g1_policy()->max_pause_time_ms(),
3711 gc_cause);
3712 VMThread::execute(&op);
3713
3714 HeapWord* result = op.result();
3715 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3716 assert(result == NULL || ret_succeeded,
3717 "the result should be NULL if the VM did not succeed");
3718 *succeeded = ret_succeeded;
3719
3720 assert_heap_not_locked();
3721 return result;
3722 }
3723
3724 void
3725 G1CollectedHeap::doConcurrentMark() {
3726 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3727 if (!_cmThread->in_progress()) {
3728 _cmThread->set_started();
3729 CGC_lock->notify();
3730 }
3731 }
3732
3733 size_t G1CollectedHeap::pending_card_num() {
3734 size_t extra_cards = 0;
3735 JavaThread *curr = Threads::first();
3736 while (curr != NULL) {
3737 DirtyCardQueue& dcq = curr->dirty_card_queue();
3738 extra_cards += dcq.size();
3739 curr = curr->next();
3740 }
3741 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3742 size_t buffer_size = dcqs.buffer_size();
3743 size_t buffer_num = dcqs.completed_buffers_num();
3744
3745 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3746 // in bytes - not the number of 'entries'. We need to convert
3747 // into a number of cards.
3748 return (buffer_size * buffer_num + extra_cards) / oopSize;
3749 }
3750
3751 size_t G1CollectedHeap::cards_scanned() {
3752 return g1_rem_set()->cardsScanned();
3753 }
3754
3755 void
3756 G1CollectedHeap::setup_surviving_young_words() {
3757 assert(_surviving_young_words == NULL, "pre-condition");
3758 uint array_length = g1_policy()->young_cset_region_length();
3759 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3760 if (_surviving_young_words == NULL) {
3761 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3762 "Not enough space for young surv words summary.");
3763 }
3764 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3765 #ifdef ASSERT
3766 for (uint i = 0; i < array_length; ++i) {
3767 assert( _surviving_young_words[i] == 0, "memset above" );
3768 }
3769 #endif // !ASSERT
3770 }
3771
3772 void
3773 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3774 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3775 uint array_length = g1_policy()->young_cset_region_length();
3776 for (uint i = 0; i < array_length; ++i) {
3777 _surviving_young_words[i] += surv_young_words[i];
3778 }
3779 }
3780
3781 void
3782 G1CollectedHeap::cleanup_surviving_young_words() {
3783 guarantee( _surviving_young_words != NULL, "pre-condition" );
3784 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3785 _surviving_young_words = NULL;
3786 }
3787
3788 #ifdef ASSERT
3789 class VerifyCSetClosure: public HeapRegionClosure {
3790 public:
3791 bool doHeapRegion(HeapRegion* hr) {
3792 // Here we check that the CSet region's RSet is ready for parallel
3793 // iteration. The fields that we'll verify are only manipulated
3794 // when the region is part of a CSet and is collected. Afterwards,
3795 // we reset these fields when we clear the region's RSet (when the
3796 // region is freed) so they are ready when the region is
3797 // re-allocated. The only exception to this is if there's an
3798 // evacuation failure and instead of freeing the region we leave
3799 // it in the heap. In that case, we reset these fields during
3800 // evacuation failure handling.
3801 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3802
3803 // Here's a good place to add any other checks we'd like to
3804 // perform on CSet regions.
3805 return false;
3806 }
3807 };
3808 #endif // ASSERT
3809
3810 #if TASKQUEUE_STATS
3811 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3812 st->print_raw_cr("GC Task Stats");
3813 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3814 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3815 }
3816
3817 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3818 print_taskqueue_stats_hdr(st);
3819
3820 TaskQueueStats totals;
3821 const int n = workers() != NULL ? workers()->total_workers() : 1;
3822 for (int i = 0; i < n; ++i) {
3823 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3824 totals += task_queue(i)->stats;
3825 }
3826 st->print_raw("tot "); totals.print(st); st->cr();
3827
3828 DEBUG_ONLY(totals.verify());
3829 }
3830
3831 void G1CollectedHeap::reset_taskqueue_stats() {
3832 const int n = workers() != NULL ? workers()->total_workers() : 1;
3833 for (int i = 0; i < n; ++i) {
3834 task_queue(i)->stats.reset();
3835 }
3836 }
3837 #endif // TASKQUEUE_STATS
3838
3839 void G1CollectedHeap::log_gc_header() {
3840 if (!G1Log::fine()) {
3841 return;
3842 }
3843
3844 gclog_or_tty->date_stamp(PrintGCDateStamps);
3845 gclog_or_tty->stamp(PrintGCTimeStamps);
3846
3847 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3848 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3849 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3850
3851 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3852 }
3853
3854 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3855 if (!G1Log::fine()) {
3856 return;
3857 }
3858
3859 if (G1Log::finer()) {
3860 if (evacuation_failed()) {
3861 gclog_or_tty->print(" (to-space exhausted)");
3862 }
3863 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3864 g1_policy()->phase_times()->note_gc_end();
3865 g1_policy()->phase_times()->print(pause_time_sec);
3866 g1_policy()->print_detailed_heap_transition();
3867 } else {
3868 if (evacuation_failed()) {
3869 gclog_or_tty->print("--");
3870 }
3871 g1_policy()->print_heap_transition();
3872 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3873 }
3874 gclog_or_tty->flush();
3875 }
3876
3877 bool
3878 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3879 assert_at_safepoint(true /* should_be_vm_thread */);
3880 guarantee(!is_gc_active(), "collection is not reentrant");
3881
3882 if (GC_locker::check_active_before_gc()) {
3883 return false;
3884 }
3885
3886 _gc_timer_stw->register_gc_start(os::elapsed_counter());
3887
3888 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3889
3890 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3891 ResourceMark rm;
3892
3893 print_heap_before_gc();
3894 trace_heap_before_gc(_gc_tracer_stw);
3895
3896 HRSPhaseSetter x(HRSPhaseEvacuation);
3897 verify_region_sets_optional();
3898 verify_dirty_young_regions();
3899
3900 // This call will decide whether this pause is an initial-mark
3901 // pause. If it is, during_initial_mark_pause() will return true
3902 // for the duration of this pause.
3903 g1_policy()->decide_on_conc_mark_initiation();
3904
3905 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3906 assert(!g1_policy()->during_initial_mark_pause() ||
3907 g1_policy()->gcs_are_young(), "sanity");
3908
3909 // We also do not allow mixed GCs during marking.
3910 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3911
3912 // Record whether this pause is an initial mark. When the current
3913 // thread has completed its logging output and it's safe to signal
3914 // the CM thread, the flag's value in the policy has been reset.
3915 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3916
3917 // Inner scope for scope based logging, timers, and stats collection
3918 {
3919 EvacuationInfo evacuation_info;
3920
3921 if (g1_policy()->during_initial_mark_pause()) {
3922 // We are about to start a marking cycle, so we increment the
3923 // full collection counter.
3924 increment_old_marking_cycles_started();
3925 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3926 }
3927
3928 _gc_tracer_stw->report_yc_type(yc_type());
3929
3930 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3931
3932 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3933 workers()->active_workers() : 1);
3934 double pause_start_sec = os::elapsedTime();
3935 g1_policy()->phase_times()->note_gc_start(active_workers);
3936 log_gc_header();
3937
3938 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3939 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3940
3941 // If the secondary_free_list is not empty, append it to the
3942 // free_list. No need to wait for the cleanup operation to finish;
3943 // the region allocation code will check the secondary_free_list
3944 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3945 // set, skip this step so that the region allocation code has to
3946 // get entries from the secondary_free_list.
3947 if (!G1StressConcRegionFreeing) {
3948 append_secondary_free_list_if_not_empty_with_lock();
3949 }
3950
3951 assert(check_young_list_well_formed(), "young list should be well formed");
3952 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3953 "sanity check");
3954
3955 // Don't dynamically change the number of GC threads this early. A value of
3956 // 0 is used to indicate serial work. When parallel work is done,
3957 // it will be set.
3958
3959 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3960 IsGCActiveMark x;
3961
3962 gc_prologue(false);
3963 increment_total_collections(false /* full gc */);
3964 increment_gc_time_stamp();
3965
3966 verify_before_gc();
3967
3968 COMPILER2_PRESENT(DerivedPointerTable::clear());
3969
3970 // Please see comment in g1CollectedHeap.hpp and
3971 // G1CollectedHeap::ref_processing_init() to see how
3972 // reference processing currently works in G1.
3973
3974 // Enable discovery in the STW reference processor
3975 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3976 true /*verify_no_refs*/);
3977
3978 {
3979 // We want to temporarily turn off discovery by the
3980 // CM ref processor, if necessary, and turn it back on
3981 // on again later if we do. Using a scoped
3982 // NoRefDiscovery object will do this.
3983 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3984
3985 // Forget the current alloc region (we might even choose it to be part
3986 // of the collection set!).
3987 release_mutator_alloc_region();
3988
3989 // We should call this after we retire the mutator alloc
3990 // region(s) so that all the ALLOC / RETIRE events are generated
3991 // before the start GC event.
3992 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3993
3994 // This timing is only used by the ergonomics to handle our pause target.
3995 // It is unclear why this should not include the full pause. We will
3996 // investigate this in CR 7178365.
3997 //
3998 // Preserving the old comment here if that helps the investigation:
3999 //
4000 // The elapsed time induced by the start time below deliberately elides
4001 // the possible verification above.
4002 double sample_start_time_sec = os::elapsedTime();
4003
4004 #if YOUNG_LIST_VERBOSE
4005 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4006 _young_list->print();
4007 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4008 #endif // YOUNG_LIST_VERBOSE
4009
4010 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4011
4012 double scan_wait_start = os::elapsedTime();
4013 // We have to wait until the CM threads finish scanning the
4014 // root regions as it's the only way to ensure that all the
4015 // objects on them have been correctly scanned before we start
4016 // moving them during the GC.
4017 bool waited = _cm->root_regions()->wait_until_scan_finished();
4018 double wait_time_ms = 0.0;
4019 if (waited) {
4020 double scan_wait_end = os::elapsedTime();
4021 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4022 }
4023 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4024
4025 #if YOUNG_LIST_VERBOSE
4026 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4027 _young_list->print();
4028 #endif // YOUNG_LIST_VERBOSE
4029
4030 if (g1_policy()->during_initial_mark_pause()) {
4031 concurrent_mark()->checkpointRootsInitialPre();
4032 }
4033
4034 #if YOUNG_LIST_VERBOSE
4035 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4036 _young_list->print();
4037 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4038 #endif // YOUNG_LIST_VERBOSE
4039
4040 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4041
4042 _cm->note_start_of_gc();
4043 // We should not verify the per-thread SATB buffers given that
4044 // we have not filtered them yet (we'll do so during the
4045 // GC). We also call this after finalize_cset() to
4046 // ensure that the CSet has been finalized.
4047 _cm->verify_no_cset_oops(true /* verify_stacks */,
4048 true /* verify_enqueued_buffers */,
4049 false /* verify_thread_buffers */,
4050 true /* verify_fingers */);
4051
4052 if (_hr_printer.is_active()) {
4053 HeapRegion* hr = g1_policy()->collection_set();
4054 while (hr != NULL) {
4055 G1HRPrinter::RegionType type;
4056 if (!hr->is_young()) {
4057 type = G1HRPrinter::Old;
4058 } else if (hr->is_survivor()) {
4059 type = G1HRPrinter::Survivor;
4060 } else {
4061 type = G1HRPrinter::Eden;
4062 }
4063 _hr_printer.cset(hr);
4064 hr = hr->next_in_collection_set();
4065 }
4066 }
4067
4068 #ifdef ASSERT
4069 VerifyCSetClosure cl;
4070 collection_set_iterate(&cl);
4071 #endif // ASSERT
4072
4073 setup_surviving_young_words();
4074
4075 // Initialize the GC alloc regions.
4076 init_gc_alloc_regions(evacuation_info);
4077
4078 // Actually do the work...
4079 evacuate_collection_set(evacuation_info);
4080
4081 // We do this to mainly verify the per-thread SATB buffers
4082 // (which have been filtered by now) since we didn't verify
4083 // them earlier. No point in re-checking the stacks / enqueued
4084 // buffers given that the CSet has not changed since last time
4085 // we checked.
4086 _cm->verify_no_cset_oops(false /* verify_stacks */,
4087 false /* verify_enqueued_buffers */,
4088 true /* verify_thread_buffers */,
4089 true /* verify_fingers */);
4090
4091 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4092 g1_policy()->clear_collection_set();
4093
4094 cleanup_surviving_young_words();
4095
4096 // Start a new incremental collection set for the next pause.
4097 g1_policy()->start_incremental_cset_building();
4098
4099 // Clear the _cset_fast_test bitmap in anticipation of adding
4100 // regions to the incremental collection set for the next
4101 // evacuation pause.
4102 clear_cset_fast_test();
4103
4104 _young_list->reset_sampled_info();
4105
4106 // Don't check the whole heap at this point as the
4107 // GC alloc regions from this pause have been tagged
4108 // as survivors and moved on to the survivor list.
4109 // Survivor regions will fail the !is_young() check.
4110 assert(check_young_list_empty(false /* check_heap */),
4111 "young list should be empty");
4112
4113 #if YOUNG_LIST_VERBOSE
4114 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4115 _young_list->print();
4116 #endif // YOUNG_LIST_VERBOSE
4117
4118 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4119 _young_list->first_survivor_region(),
4120 _young_list->last_survivor_region());
4121
4122 _young_list->reset_auxilary_lists();
4123
4124 if (evacuation_failed()) {
4125 _summary_bytes_used = recalculate_used();
4126 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4127 for (uint i = 0; i < n_queues; i++) {
4128 if (_evacuation_failed_info_array[i].has_failed()) {
4129 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4130 }
4131 }
4132 } else {
4133 // The "used" of the the collection set have already been subtracted
4134 // when they were freed. Add in the bytes evacuated.
4135 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4136 }
4137
4138 if (g1_policy()->during_initial_mark_pause()) {
4139 // We have to do this before we notify the CM threads that
4140 // they can start working to make sure that all the
4141 // appropriate initialization is done on the CM object.
4142 concurrent_mark()->checkpointRootsInitialPost();
4143 set_marking_started();
4144 // Note that we don't actually trigger the CM thread at
4145 // this point. We do that later when we're sure that
4146 // the current thread has completed its logging output.
4147 }
4148
4149 allocate_dummy_regions();
4150
4151 #if YOUNG_LIST_VERBOSE
4152 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4153 _young_list->print();
4154 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4155 #endif // YOUNG_LIST_VERBOSE
4156
4157 init_mutator_alloc_region();
4158
4159 {
4160 size_t expand_bytes = g1_policy()->expansion_amount();
4161 if (expand_bytes > 0) {
4162 size_t bytes_before = capacity();
4163 // No need for an ergo verbose message here,
4164 // expansion_amount() does this when it returns a value > 0.
4165 if (!expand(expand_bytes)) {
4166 // We failed to expand the heap so let's verify that
4167 // committed/uncommitted amount match the backing store
4168 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4169 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4170 }
4171 }
4172 }
4173
4174 // We redo the verification but now wrt to the new CSet which
4175 // has just got initialized after the previous CSet was freed.
4176 _cm->verify_no_cset_oops(true /* verify_stacks */,
4177 true /* verify_enqueued_buffers */,
4178 true /* verify_thread_buffers */,
4179 true /* verify_fingers */);
4180 _cm->note_end_of_gc();
4181
4182 // This timing is only used by the ergonomics to handle our pause target.
4183 // It is unclear why this should not include the full pause. We will
4184 // investigate this in CR 7178365.
4185 double sample_end_time_sec = os::elapsedTime();
4186 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4187 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4188
4189 MemoryService::track_memory_usage();
4190
4191 // In prepare_for_verify() below we'll need to scan the deferred
4192 // update buffers to bring the RSets up-to-date if
4193 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4194 // the update buffers we'll probably need to scan cards on the
4195 // regions we just allocated to (i.e., the GC alloc
4196 // regions). However, during the last GC we called
4197 // set_saved_mark() on all the GC alloc regions, so card
4198 // scanning might skip the [saved_mark_word()...top()] area of
4199 // those regions (i.e., the area we allocated objects into
4200 // during the last GC). But it shouldn't. Given that
4201 // saved_mark_word() is conditional on whether the GC time stamp
4202 // on the region is current or not, by incrementing the GC time
4203 // stamp here we invalidate all the GC time stamps on all the
4204 // regions and saved_mark_word() will simply return top() for
4205 // all the regions. This is a nicer way of ensuring this rather
4206 // than iterating over the regions and fixing them. In fact, the
4207 // GC time stamp increment here also ensures that
4208 // saved_mark_word() will return top() between pauses, i.e.,
4209 // during concurrent refinement. So we don't need the
4210 // is_gc_active() check to decided which top to use when
4211 // scanning cards (see CR 7039627).
4212 increment_gc_time_stamp();
4213
4214 verify_after_gc();
4215
4216 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4217 ref_processor_stw()->verify_no_references_recorded();
4218
4219 // CM reference discovery will be re-enabled if necessary.
4220 }
4221
4222 // We should do this after we potentially expand the heap so
4223 // that all the COMMIT events are generated before the end GC
4224 // event, and after we retire the GC alloc regions so that all
4225 // RETIRE events are generated before the end GC event.
4226 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4227
4228 if (mark_in_progress()) {
4229 concurrent_mark()->update_g1_committed();
4230 }
4231
4232 #ifdef TRACESPINNING
4233 ParallelTaskTerminator::print_termination_counts();
4234 #endif
4235
4236 gc_epilogue(false);
4237 }
4238
4239 // Print the remainder of the GC log output.
4240 log_gc_footer(os::elapsedTime() - pause_start_sec);
4241
4242 // It is not yet to safe to tell the concurrent mark to
4243 // start as we have some optional output below. We don't want the
4244 // output from the concurrent mark thread interfering with this
4245 // logging output either.
4246
4247 _hrs.verify_optional();
4248 verify_region_sets_optional();
4249
4250 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4251 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4252
4253 print_heap_after_gc();
4254 trace_heap_after_gc(_gc_tracer_stw);
4255
4256 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4257 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4258 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4259 // before any GC notifications are raised.
4260 g1mm()->update_sizes();
4261
4262 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4263 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4264 _gc_timer_stw->register_gc_end(os::elapsed_counter());
4265 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4266 }
4267 // It should now be safe to tell the concurrent mark thread to start
4268 // without its logging output interfering with the logging output
4269 // that came from the pause.
4270
4271 if (should_start_conc_mark) {
4272 // CAUTION: after the doConcurrentMark() call below,
4273 // the concurrent marking thread(s) could be running
4274 // concurrently with us. Make sure that anything after
4275 // this point does not assume that we are the only GC thread
4276 // running. Note: of course, the actual marking work will
4277 // not start until the safepoint itself is released in
4278 // ConcurrentGCThread::safepoint_desynchronize().
4279 doConcurrentMark();
4280 }
4281
4282 return true;
4283 }
4284
4285 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4286 {
4287 size_t gclab_word_size;
4288 switch (purpose) {
4289 case GCAllocForSurvived:
4290 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4291 break;
4292 case GCAllocForTenured:
4293 gclab_word_size = _old_plab_stats.desired_plab_sz();
4294 break;
4295 default:
4296 assert(false, "unknown GCAllocPurpose");
4297 gclab_word_size = _old_plab_stats.desired_plab_sz();
4298 break;
4299 }
4300
4301 // Prevent humongous PLAB sizes for two reasons:
4302 // * PLABs are allocated using a similar paths as oops, but should
4303 // never be in a humongous region
4304 // * Allowing humongous PLABs needlessly churns the region free lists
4305 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4306 }
4307
4308 void G1CollectedHeap::init_mutator_alloc_region() {
4309 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4310 _mutator_alloc_region.init();
4311 }
4312
4313 void G1CollectedHeap::release_mutator_alloc_region() {
4314 _mutator_alloc_region.release();
4315 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4316 }
4317
4318 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4319 assert_at_safepoint(true /* should_be_vm_thread */);
4320
4321 _survivor_gc_alloc_region.init();
4322 _old_gc_alloc_region.init();
4323 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4324 _retained_old_gc_alloc_region = NULL;
4325
4326 // We will discard the current GC alloc region if:
4327 // a) it's in the collection set (it can happen!),
4328 // b) it's already full (no point in using it),
4329 // c) it's empty (this means that it was emptied during
4330 // a cleanup and it should be on the free list now), or
4331 // d) it's humongous (this means that it was emptied
4332 // during a cleanup and was added to the free list, but
4333 // has been subsequently used to allocate a humongous
4334 // object that may be less than the region size).
4335 if (retained_region != NULL &&
4336 !retained_region->in_collection_set() &&
4337 !(retained_region->top() == retained_region->end()) &&
4338 !retained_region->is_empty() &&
4339 !retained_region->isHumongous()) {
4340 retained_region->set_saved_mark();
4341 // The retained region was added to the old region set when it was
4342 // retired. We have to remove it now, since we don't allow regions
4343 // we allocate to in the region sets. We'll re-add it later, when
4344 // it's retired again.
4345 _old_set.remove(retained_region);
4346 bool during_im = g1_policy()->during_initial_mark_pause();
4347 retained_region->note_start_of_copying(during_im);
4348 _old_gc_alloc_region.set(retained_region);
4349 _hr_printer.reuse(retained_region);
4350 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4351 }
4352 }
4353
4354 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4355 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4356 _old_gc_alloc_region.count());
4357 _survivor_gc_alloc_region.release();
4358 // If we have an old GC alloc region to release, we'll save it in
4359 // _retained_old_gc_alloc_region. If we don't
4360 // _retained_old_gc_alloc_region will become NULL. This is what we
4361 // want either way so no reason to check explicitly for either
4362 // condition.
4363 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4364
4365 if (ResizePLAB) {
4366 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4367 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4368 }
4369 }
4370
4371 void G1CollectedHeap::abandon_gc_alloc_regions() {
4372 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4373 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4374 _retained_old_gc_alloc_region = NULL;
4375 }
4376
4377 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4378 _drain_in_progress = false;
4379 set_evac_failure_closure(cl);
4380 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4381 }
4382
4383 void G1CollectedHeap::finalize_for_evac_failure() {
4384 assert(_evac_failure_scan_stack != NULL &&
4385 _evac_failure_scan_stack->length() == 0,
4386 "Postcondition");
4387 assert(!_drain_in_progress, "Postcondition");
4388 delete _evac_failure_scan_stack;
4389 _evac_failure_scan_stack = NULL;
4390 }
4391
4392 void G1CollectedHeap::remove_self_forwarding_pointers() {
4393 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4394
4395 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4396
4397 if (G1CollectedHeap::use_parallel_gc_threads()) {
4398 set_par_threads();
4399 workers()->run_task(&rsfp_task);
4400 set_par_threads(0);
4401 } else {
4402 rsfp_task.work(0);
4403 }
4404
4405 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4406
4407 // Reset the claim values in the regions in the collection set.
4408 reset_cset_heap_region_claim_values();
4409
4410 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4411
4412 // Now restore saved marks, if any.
4413 assert(_objs_with_preserved_marks.size() ==
4414 _preserved_marks_of_objs.size(), "Both or none.");
4415 while (!_objs_with_preserved_marks.is_empty()) {
4416 oop obj = _objs_with_preserved_marks.pop();
4417 markOop m = _preserved_marks_of_objs.pop();
4418 obj->set_mark(m);
4419 }
4420 _objs_with_preserved_marks.clear(true);
4421 _preserved_marks_of_objs.clear(true);
4422 }
4423
4424 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4425 _evac_failure_scan_stack->push(obj);
4426 }
4427
4428 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4429 assert(_evac_failure_scan_stack != NULL, "precondition");
4430
4431 while (_evac_failure_scan_stack->length() > 0) {
4432 oop obj = _evac_failure_scan_stack->pop();
4433 _evac_failure_closure->set_region(heap_region_containing(obj));
4434 obj->oop_iterate_backwards(_evac_failure_closure);
4435 }
4436 }
4437
4438 oop
4439 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4440 oop old) {
4441 assert(obj_in_cs(old),
4442 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4443 (HeapWord*) old));
4444 markOop m = old->mark();
4445 oop forward_ptr = old->forward_to_atomic(old);
4446 if (forward_ptr == NULL) {
4447 // Forward-to-self succeeded.
4448 assert(_par_scan_state != NULL, "par scan state");
4449 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4450 uint queue_num = _par_scan_state->queue_num();
4451
4452 _evacuation_failed = true;
4453 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4454 if (_evac_failure_closure != cl) {
4455 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4456 assert(!_drain_in_progress,
4457 "Should only be true while someone holds the lock.");
4458 // Set the global evac-failure closure to the current thread's.
4459 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4460 set_evac_failure_closure(cl);
4461 // Now do the common part.
4462 handle_evacuation_failure_common(old, m);
4463 // Reset to NULL.
4464 set_evac_failure_closure(NULL);
4465 } else {
4466 // The lock is already held, and this is recursive.
4467 assert(_drain_in_progress, "This should only be the recursive case.");
4468 handle_evacuation_failure_common(old, m);
4469 }
4470 return old;
4471 } else {
4472 // Forward-to-self failed. Either someone else managed to allocate
4473 // space for this object (old != forward_ptr) or they beat us in
4474 // self-forwarding it (old == forward_ptr).
4475 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4476 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4477 "should not be in the CSet",
4478 (HeapWord*) old, (HeapWord*) forward_ptr));
4479 return forward_ptr;
4480 }
4481 }
4482
4483 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4484 preserve_mark_if_necessary(old, m);
4485
4486 HeapRegion* r = heap_region_containing(old);
4487 if (!r->evacuation_failed()) {
4488 r->set_evacuation_failed(true);
4489 _hr_printer.evac_failure(r);
4490 }
4491
4492 push_on_evac_failure_scan_stack(old);
4493
4494 if (!_drain_in_progress) {
4495 // prevent recursion in copy_to_survivor_space()
4496 _drain_in_progress = true;
4497 drain_evac_failure_scan_stack();
4498 _drain_in_progress = false;
4499 }
4500 }
4501
4502 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4503 assert(evacuation_failed(), "Oversaving!");
4504 // We want to call the "for_promotion_failure" version only in the
4505 // case of a promotion failure.
4506 if (m->must_be_preserved_for_promotion_failure(obj)) {
4507 _objs_with_preserved_marks.push(obj);
4508 _preserved_marks_of_objs.push(m);
4509 }
4510 }
4511
4512 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4513 size_t word_size) {
4514 if (purpose == GCAllocForSurvived) {
4515 HeapWord* result = survivor_attempt_allocation(word_size);
4516 if (result != NULL) {
4517 return result;
4518 } else {
4519 // Let's try to allocate in the old gen in case we can fit the
4520 // object there.
4521 return old_attempt_allocation(word_size);
4522 }
4523 } else {
4524 assert(purpose == GCAllocForTenured, "sanity");
4525 HeapWord* result = old_attempt_allocation(word_size);
4526 if (result != NULL) {
4527 return result;
4528 } else {
4529 // Let's try to allocate in the survivors in case we can fit the
4530 // object there.
4531 return survivor_attempt_allocation(word_size);
4532 }
4533 }
4534
4535 ShouldNotReachHere();
4536 // Trying to keep some compilers happy.
4537 return NULL;
4538 }
4539
4540 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4541 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4542
4543 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4544 : _g1h(g1h),
4545 _refs(g1h->task_queue(queue_num)),
4546 _dcq(&g1h->dirty_card_queue_set()),
4547 _ct_bs(g1h->g1_barrier_set()),
4548 _g1_rem(g1h->g1_rem_set()),
4549 _hash_seed(17), _queue_num(queue_num),
4550 _term_attempts(0),
4551 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4552 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4553 _age_table(false),
4554 _strong_roots_time(0), _term_time(0),
4555 _alloc_buffer_waste(0), _undo_waste(0) {
4556 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4557 // we "sacrifice" entry 0 to keep track of surviving bytes for
4558 // non-young regions (where the age is -1)
4559 // We also add a few elements at the beginning and at the end in
4560 // an attempt to eliminate cache contention
4561 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4562 uint array_length = PADDING_ELEM_NUM +
4563 real_length +
4564 PADDING_ELEM_NUM;
4565 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4566 if (_surviving_young_words_base == NULL)
4567 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4568 "Not enough space for young surv histo.");
4569 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4570 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4571
4572 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4573 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4574
4575 _start = os::elapsedTime();
4576 }
4577
4578 void
4579 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4580 {
4581 st->print_raw_cr("GC Termination Stats");
4582 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4583 " ------waste (KiB)------");
4584 st->print_raw_cr("thr ms ms % ms % attempts"
4585 " total alloc undo");
4586 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4587 " ------- ------- -------");
4588 }
4589
4590 void
4591 G1ParScanThreadState::print_termination_stats(int i,
4592 outputStream* const st) const
4593 {
4594 const double elapsed_ms = elapsed_time() * 1000.0;
4595 const double s_roots_ms = strong_roots_time() * 1000.0;
4596 const double term_ms = term_time() * 1000.0;
4597 st->print_cr("%3d %9.2f %9.2f %6.2f "
4598 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4599 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4600 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4601 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4602 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4603 alloc_buffer_waste() * HeapWordSize / K,
4604 undo_waste() * HeapWordSize / K);
4605 }
4606
4607 #ifdef ASSERT
4608 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4609 assert(ref != NULL, "invariant");
4610 assert(UseCompressedOops, "sanity");
4611 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4612 oop p = oopDesc::load_decode_heap_oop(ref);
4613 assert(_g1h->is_in_g1_reserved(p),
4614 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4615 return true;
4616 }
4617
4618 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4619 assert(ref != NULL, "invariant");
4620 if (has_partial_array_mask(ref)) {
4621 // Must be in the collection set--it's already been copied.
4622 oop p = clear_partial_array_mask(ref);
4623 assert(_g1h->obj_in_cs(p),
4624 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4625 } else {
4626 oop p = oopDesc::load_decode_heap_oop(ref);
4627 assert(_g1h->is_in_g1_reserved(p),
4628 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4629 }
4630 return true;
4631 }
4632
4633 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4634 if (ref.is_narrow()) {
4635 return verify_ref((narrowOop*) ref);
4636 } else {
4637 return verify_ref((oop*) ref);
4638 }
4639 }
4640 #endif // ASSERT
4641
4642 void G1ParScanThreadState::trim_queue() {
4643 assert(_evac_cl != NULL, "not set");
4644 assert(_evac_failure_cl != NULL, "not set");
4645 assert(_partial_scan_cl != NULL, "not set");
4646
4647 StarTask ref;
4648 do {
4649 // Drain the overflow stack first, so other threads can steal.
4650 while (refs()->pop_overflow(ref)) {
4651 deal_with_reference(ref);
4652 }
4653
4654 while (refs()->pop_local(ref)) {
4655 deal_with_reference(ref);
4656 }
4657 } while (!refs()->is_empty());
4658 }
4659
4660 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4661 G1ParScanThreadState* par_scan_state) :
4662 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4663 _par_scan_state(par_scan_state),
4664 _worker_id(par_scan_state->queue_num()),
4665 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4666 _mark_in_progress(_g1->mark_in_progress()) { }
4667
4668 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4669 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4670 #ifdef ASSERT
4671 HeapRegion* hr = _g1->heap_region_containing(obj);
4672 assert(hr != NULL, "sanity");
4673 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4674 #endif // ASSERT
4675
4676 // We know that the object is not moving so it's safe to read its size.
4677 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4678 }
4679
4680 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4681 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4682 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4683 #ifdef ASSERT
4684 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4685 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4686 assert(from_obj != to_obj, "should not be self-forwarded");
4687
4688 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4689 assert(from_hr != NULL, "sanity");
4690 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4691
4692 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4693 assert(to_hr != NULL, "sanity");
4694 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4695 #endif // ASSERT
4696
4697 // The object might be in the process of being copied by another
4698 // worker so we cannot trust that its to-space image is
4699 // well-formed. So we have to read its size from its from-space
4700 // image which we know should not be changing.
4701 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4702 }
4703
4704 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4705 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4706 ::copy_to_survivor_space(oop old) {
4707 size_t word_sz = old->size();
4708 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4709 // +1 to make the -1 indexes valid...
4710 int young_index = from_region->young_index_in_cset()+1;
4711 assert( (from_region->is_young() && young_index > 0) ||
4712 (!from_region->is_young() && young_index == 0), "invariant" );
4713 G1CollectorPolicy* g1p = _g1->g1_policy();
4714 markOop m = old->mark();
4715 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4716 : m->age();
4717 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4718 word_sz);
4719 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4720 #ifndef PRODUCT
4721 // Should this evacuation fail?
4722 if (_g1->evacuation_should_fail()) {
4723 if (obj_ptr != NULL) {
4724 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4725 obj_ptr = NULL;
4726 }
4727 }
4728 #endif // !PRODUCT
4729
4730 if (obj_ptr == NULL) {
4731 // This will either forward-to-self, or detect that someone else has
4732 // installed a forwarding pointer.
4733 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4734 }
4735
4736 oop obj = oop(obj_ptr);
4737
4738 // We're going to allocate linearly, so might as well prefetch ahead.
4739 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4740
4741 oop forward_ptr = old->forward_to_atomic(obj);
4742 if (forward_ptr == NULL) {
4743 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4744 if (g1p->track_object_age(alloc_purpose)) {
4745 // We could simply do obj->incr_age(). However, this causes a
4746 // performance issue. obj->incr_age() will first check whether
4747 // the object has a displaced mark by checking its mark word;
4748 // getting the mark word from the new location of the object
4749 // stalls. So, given that we already have the mark word and we
4750 // are about to install it anyway, it's better to increase the
4751 // age on the mark word, when the object does not have a
4752 // displaced mark word. We're not expecting many objects to have
4753 // a displaced marked word, so that case is not optimized
4754 // further (it could be...) and we simply call obj->incr_age().
4755
4756 if (m->has_displaced_mark_helper()) {
4757 // in this case, we have to install the mark word first,
4758 // otherwise obj looks to be forwarded (the old mark word,
4759 // which contains the forward pointer, was copied)
4760 obj->set_mark(m);
4761 obj->incr_age();
4762 } else {
4763 m = m->incr_age();
4764 obj->set_mark(m);
4765 }
4766 _par_scan_state->age_table()->add(obj, word_sz);
4767 } else {
4768 obj->set_mark(m);
4769 }
4770
4771 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4772 surv_young_words[young_index] += word_sz;
4773
4774 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4775 // We keep track of the next start index in the length field of
4776 // the to-space object. The actual length can be found in the
4777 // length field of the from-space object.
4778 arrayOop(obj)->set_length(0);
4779 oop* old_p = set_partial_array_mask(old);
4780 _par_scan_state->push_on_queue(old_p);
4781 } else {
4782 // No point in using the slower heap_region_containing() method,
4783 // given that we know obj is in the heap.
4784 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4785 obj->oop_iterate_backwards(&_scanner);
4786 }
4787 } else {
4788 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4789 obj = forward_ptr;
4790 }
4791 return obj;
4792 }
4793
4794 template <class T>
4795 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4796 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4797 _scanned_klass->record_modified_oops();
4798 }
4799 }
4800
4801 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4802 template <class T>
4803 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4804 ::do_oop_work(T* p) {
4805 oop obj = oopDesc::load_decode_heap_oop(p);
4806 assert(barrier != G1BarrierRS || obj != NULL,
4807 "Precondition: G1BarrierRS implies obj is non-NULL");
4808
4809 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4810
4811 // here the null check is implicit in the cset_fast_test() test
4812 if (_g1->in_cset_fast_test(obj)) {
4813 oop forwardee;
4814 if (obj->is_forwarded()) {
4815 forwardee = obj->forwardee();
4816 } else {
4817 forwardee = copy_to_survivor_space(obj);
4818 }
4819 assert(forwardee != NULL, "forwardee should not be NULL");
4820 oopDesc::encode_store_heap_oop(p, forwardee);
4821 if (do_mark_object && forwardee != obj) {
4822 // If the object is self-forwarded we don't need to explicitly
4823 // mark it, the evacuation failure protocol will do so.
4824 mark_forwarded_object(obj, forwardee);
4825 }
4826
4827 // When scanning the RS, we only care about objs in CS.
4828 if (barrier == G1BarrierRS) {
4829 _par_scan_state->update_rs(_from, p, _worker_id);
4830 } else if (barrier == G1BarrierKlass) {
4831 do_klass_barrier(p, forwardee);
4832 }
4833 } else {
4834 // The object is not in collection set. If we're a root scanning
4835 // closure during an initial mark pause (i.e. do_mark_object will
4836 // be true) then attempt to mark the object.
4837 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4838 mark_object(obj);
4839 }
4840 }
4841
4842 if (barrier == G1BarrierEvac && obj != NULL) {
4843 _par_scan_state->update_rs(_from, p, _worker_id);
4844 }
4845
4846 if (do_gen_barrier && obj != NULL) {
4847 par_do_barrier(p);
4848 }
4849 }
4850
4851 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4852 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4853
4854 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4855 assert(has_partial_array_mask(p), "invariant");
4856 oop from_obj = clear_partial_array_mask(p);
4857
4858 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4859 assert(from_obj->is_objArray(), "must be obj array");
4860 objArrayOop from_obj_array = objArrayOop(from_obj);
4861 // The from-space object contains the real length.
4862 int length = from_obj_array->length();
4863
4864 assert(from_obj->is_forwarded(), "must be forwarded");
4865 oop to_obj = from_obj->forwardee();
4866 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4867 objArrayOop to_obj_array = objArrayOop(to_obj);
4868 // We keep track of the next start index in the length field of the
4869 // to-space object.
4870 int next_index = to_obj_array->length();
4871 assert(0 <= next_index && next_index < length,
4872 err_msg("invariant, next index: %d, length: %d", next_index, length));
4873
4874 int start = next_index;
4875 int end = length;
4876 int remainder = end - start;
4877 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4878 if (remainder > 2 * ParGCArrayScanChunk) {
4879 end = start + ParGCArrayScanChunk;
4880 to_obj_array->set_length(end);
4881 // Push the remainder before we process the range in case another
4882 // worker has run out of things to do and can steal it.
4883 oop* from_obj_p = set_partial_array_mask(from_obj);
4884 _par_scan_state->push_on_queue(from_obj_p);
4885 } else {
4886 assert(length == end, "sanity");
4887 // We'll process the final range for this object. Restore the length
4888 // so that the heap remains parsable in case of evacuation failure.
4889 to_obj_array->set_length(end);
4890 }
4891 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4892 // Process indexes [start,end). It will also process the header
4893 // along with the first chunk (i.e., the chunk with start == 0).
4894 // Note that at this point the length field of to_obj_array is not
4895 // correct given that we are using it to keep track of the next
4896 // start index. oop_iterate_range() (thankfully!) ignores the length
4897 // field and only relies on the start / end parameters. It does
4898 // however return the size of the object which will be incorrect. So
4899 // we have to ignore it even if we wanted to use it.
4900 to_obj_array->oop_iterate_range(&_scanner, start, end);
4901 }
4902
4903 class G1ParEvacuateFollowersClosure : public VoidClosure {
4904 protected:
4905 G1CollectedHeap* _g1h;
4906 G1ParScanThreadState* _par_scan_state;
4907 RefToScanQueueSet* _queues;
4908 ParallelTaskTerminator* _terminator;
4909
4910 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4911 RefToScanQueueSet* queues() { return _queues; }
4912 ParallelTaskTerminator* terminator() { return _terminator; }
4913
4914 public:
4915 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4916 G1ParScanThreadState* par_scan_state,
4917 RefToScanQueueSet* queues,
4918 ParallelTaskTerminator* terminator)
4919 : _g1h(g1h), _par_scan_state(par_scan_state),
4920 _queues(queues), _terminator(terminator) {}
4921
4922 void do_void();
4923
4924 private:
4925 inline bool offer_termination();
4926 };
4927
4928 bool G1ParEvacuateFollowersClosure::offer_termination() {
4929 G1ParScanThreadState* const pss = par_scan_state();
4930 pss->start_term_time();
4931 const bool res = terminator()->offer_termination();
4932 pss->end_term_time();
4933 return res;
4934 }
4935
4936 void G1ParEvacuateFollowersClosure::do_void() {
4937 StarTask stolen_task;
4938 G1ParScanThreadState* const pss = par_scan_state();
4939 pss->trim_queue();
4940
4941 do {
4942 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4943 assert(pss->verify_task(stolen_task), "sanity");
4944 if (stolen_task.is_narrow()) {
4945 pss->deal_with_reference((narrowOop*) stolen_task);
4946 } else {
4947 pss->deal_with_reference((oop*) stolen_task);
4948 }
4949
4950 // We've just processed a reference and we might have made
4951 // available new entries on the queues. So we have to make sure
4952 // we drain the queues as necessary.
4953 pss->trim_queue();
4954 }
4955 } while (!offer_termination());
4956
4957 pss->retire_alloc_buffers();
4958 }
4959
4960 class G1KlassScanClosure : public KlassClosure {
4961 G1ParCopyHelper* _closure;
4962 bool _process_only_dirty;
4963 int _count;
4964 public:
4965 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4966 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4967 void do_klass(Klass* klass) {
4968 // If the klass has not been dirtied we know that there's
4969 // no references into the young gen and we can skip it.
4970 if (!_process_only_dirty || klass->has_modified_oops()) {
4971 // Clean the klass since we're going to scavenge all the metadata.
4972 klass->clear_modified_oops();
4973
4974 // Tell the closure that this klass is the Klass to scavenge
4975 // and is the one to dirty if oops are left pointing into the young gen.
4976 _closure->set_scanned_klass(klass);
4977
4978 klass->oops_do(_closure);
4979
4980 _closure->set_scanned_klass(NULL);
4981 }
4982 _count++;
4983 }
4984 };
4985
4986 class G1ParTask : public AbstractGangTask {
4987 protected:
4988 G1CollectedHeap* _g1h;
4989 RefToScanQueueSet *_queues;
4990 ParallelTaskTerminator _terminator;
4991 uint _n_workers;
4992
4993 Mutex _stats_lock;
4994 Mutex* stats_lock() { return &_stats_lock; }
4995
4996 size_t getNCards() {
4997 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4998 / G1BlockOffsetSharedArray::N_bytes;
4999 }
5000
5001 public:
5002 G1ParTask(G1CollectedHeap* g1h,
5003 RefToScanQueueSet *task_queues)
5004 : AbstractGangTask("G1 collection"),
5005 _g1h(g1h),
5006 _queues(task_queues),
5007 _terminator(0, _queues),
5008 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
5009 {}
5010
5011 RefToScanQueueSet* queues() { return _queues; }
5012
5013 RefToScanQueue *work_queue(int i) {
5014 return queues()->queue(i);
5015 }
5016
5017 ParallelTaskTerminator* terminator() { return &_terminator; }
5018
5019 virtual void set_for_termination(int active_workers) {
5020 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5021 // in the young space (_par_seq_tasks) in the G1 heap
5022 // for SequentialSubTasksDone.
5023 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5024 // both of which need setting by set_n_termination().
5025 _g1h->SharedHeap::set_n_termination(active_workers);
5026 _g1h->set_n_termination(active_workers);
5027 terminator()->reset_for_reuse(active_workers);
5028 _n_workers = active_workers;
5029 }
5030
5031 void work(uint worker_id) {
5032 if (worker_id >= _n_workers) return; // no work needed this round
5033
5034 double start_time_ms = os::elapsedTime() * 1000.0;
5035 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5036
5037 {
5038 ResourceMark rm;
5039 HandleMark hm;
5040
5041 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5042
5043 G1ParScanThreadState pss(_g1h, worker_id);
5044 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5045 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5046 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5047
5048 pss.set_evac_closure(&scan_evac_cl);
5049 pss.set_evac_failure_closure(&evac_failure_cl);
5050 pss.set_partial_scan_closure(&partial_scan_cl);
5051
5052 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5053 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5054
5055 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5056 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5057
5058 bool only_young = _g1h->g1_policy()->gcs_are_young();
5059 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5060 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5061
5062 OopClosure* scan_root_cl = &only_scan_root_cl;
5063 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5064
5065 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5066 // We also need to mark copied objects.
5067 scan_root_cl = &scan_mark_root_cl;
5068 scan_klasses_cl = &scan_mark_klasses_cl_s;
5069 }
5070
5071 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5072
5073 // Don't scan the scavengable methods in the code cache as part
5074 // of strong root scanning. The code roots that point into a
5075 // region in the collection set are scanned when we scan the
5076 // region's RSet.
5077 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5078
5079 pss.start_strong_roots();
5080 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5081 SharedHeap::ScanningOption(so),
5082 scan_root_cl,
5083 &push_heap_rs_cl,
5084 scan_klasses_cl,
5085 worker_id);
5086 pss.end_strong_roots();
5087
5088 {
5089 double start = os::elapsedTime();
5090 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5091 evac.do_void();
5092 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5093 double term_ms = pss.term_time()*1000.0;
5094 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5095 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5096 }
5097 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5098 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5099
5100 if (ParallelGCVerbose) {
5101 MutexLocker x(stats_lock());
5102 pss.print_termination_stats(worker_id);
5103 }
5104
5105 assert(pss.refs()->is_empty(), "should be empty");
5106
5107 // Close the inner scope so that the ResourceMark and HandleMark
5108 // destructors are executed here and are included as part of the
5109 // "GC Worker Time".
5110 }
5111
5112 double end_time_ms = os::elapsedTime() * 1000.0;
5113 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5114 }
5115 };
5116
5117 // *** Common G1 Evacuation Stuff
5118
5119 // This method is run in a GC worker.
5120
5121 void
5122 G1CollectedHeap::
5123 g1_process_strong_roots(bool is_scavenging,
5124 ScanningOption so,
5125 OopClosure* scan_non_heap_roots,
5126 OopsInHeapRegionClosure* scan_rs,
5127 G1KlassScanClosure* scan_klasses,
5128 int worker_i) {
5129
5130 // First scan the strong roots
5131 double ext_roots_start = os::elapsedTime();
5132 double closure_app_time_sec = 0.0;
5133
5134 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5135
5136 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5137 // Walk the code cache/strong code roots w/o buffering, because StarTask
5138 // cannot handle unaligned oop locations.
5139 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5140
5141 process_strong_roots(false, // no scoping; this is parallel code
5142 is_scavenging, so,
5143 &buf_scan_non_heap_roots,
5144 &eager_scan_code_roots,
5145 scan_klasses
5146 );
5147
5148 // Now the CM ref_processor roots.
5149 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5150 // We need to treat the discovered reference lists of the
5151 // concurrent mark ref processor as roots and keep entries
5152 // (which are added by the marking threads) on them live
5153 // until they can be processed at the end of marking.
5154 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5155 }
5156
5157 // Finish up any enqueued closure apps (attributed as object copy time).
5158 buf_scan_non_heap_roots.done();
5159
5160 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5161
5162 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5163
5164 double ext_root_time_ms =
5165 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5166
5167 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5168
5169 // During conc marking we have to filter the per-thread SATB buffers
5170 // to make sure we remove any oops into the CSet (which will show up
5171 // as implicitly live).
5172 double satb_filtering_ms = 0.0;
5173 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5174 if (mark_in_progress()) {
5175 double satb_filter_start = os::elapsedTime();
5176
5177 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5178
5179 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5180 }
5181 }
5182 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5183
5184 // If this is an initial mark pause, and we're not scanning
5185 // the entire code cache, we need to mark the oops in the
5186 // strong code root lists for the regions that are not in
5187 // the collection set.
5188 // Note all threads participate in this set of root tasks.
5189 double mark_strong_code_roots_ms = 0.0;
5190 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5191 double mark_strong_roots_start = os::elapsedTime();
5192 mark_strong_code_roots(worker_i);
5193 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5194 }
5195 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5196
5197 // Now scan the complement of the collection set.
5198 if (scan_rs != NULL) {
5199 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5200 }
5201 _process_strong_tasks->all_tasks_completed();
5202 }
5203
5204 void
5205 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5206 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5207 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5208 }
5209
5210 // Weak Reference Processing support
5211
5212 // An always "is_alive" closure that is used to preserve referents.
5213 // If the object is non-null then it's alive. Used in the preservation
5214 // of referent objects that are pointed to by reference objects
5215 // discovered by the CM ref processor.
5216 class G1AlwaysAliveClosure: public BoolObjectClosure {
5217 G1CollectedHeap* _g1;
5218 public:
5219 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5220 bool do_object_b(oop p) {
5221 if (p != NULL) {
5222 return true;
5223 }
5224 return false;
5225 }
5226 };
5227
5228 bool G1STWIsAliveClosure::do_object_b(oop p) {
5229 // An object is reachable if it is outside the collection set,
5230 // or is inside and copied.
5231 return !_g1->obj_in_cs(p) || p->is_forwarded();
5232 }
5233
5234 // Non Copying Keep Alive closure
5235 class G1KeepAliveClosure: public OopClosure {
5236 G1CollectedHeap* _g1;
5237 public:
5238 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5239 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5240 void do_oop( oop* p) {
5241 oop obj = *p;
5242
5243 if (_g1->obj_in_cs(obj)) {
5244 assert( obj->is_forwarded(), "invariant" );
5245 *p = obj->forwardee();
5246 }
5247 }
5248 };
5249
5250 // Copying Keep Alive closure - can be called from both
5251 // serial and parallel code as long as different worker
5252 // threads utilize different G1ParScanThreadState instances
5253 // and different queues.
5254
5255 class G1CopyingKeepAliveClosure: public OopClosure {
5256 G1CollectedHeap* _g1h;
5257 OopClosure* _copy_non_heap_obj_cl;
5258 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5259 G1ParScanThreadState* _par_scan_state;
5260
5261 public:
5262 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5263 OopClosure* non_heap_obj_cl,
5264 OopsInHeapRegionClosure* metadata_obj_cl,
5265 G1ParScanThreadState* pss):
5266 _g1h(g1h),
5267 _copy_non_heap_obj_cl(non_heap_obj_cl),
5268 _copy_metadata_obj_cl(metadata_obj_cl),
5269 _par_scan_state(pss)
5270 {}
5271
5272 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5273 virtual void do_oop( oop* p) { do_oop_work(p); }
5274
5275 template <class T> void do_oop_work(T* p) {
5276 oop obj = oopDesc::load_decode_heap_oop(p);
5277
5278 if (_g1h->obj_in_cs(obj)) {
5279 // If the referent object has been forwarded (either copied
5280 // to a new location or to itself in the event of an
5281 // evacuation failure) then we need to update the reference
5282 // field and, if both reference and referent are in the G1
5283 // heap, update the RSet for the referent.
5284 //
5285 // If the referent has not been forwarded then we have to keep
5286 // it alive by policy. Therefore we have copy the referent.
5287 //
5288 // If the reference field is in the G1 heap then we can push
5289 // on the PSS queue. When the queue is drained (after each
5290 // phase of reference processing) the object and it's followers
5291 // will be copied, the reference field set to point to the
5292 // new location, and the RSet updated. Otherwise we need to
5293 // use the the non-heap or metadata closures directly to copy
5294 // the referent object and update the pointer, while avoiding
5295 // updating the RSet.
5296
5297 if (_g1h->is_in_g1_reserved(p)) {
5298 _par_scan_state->push_on_queue(p);
5299 } else {
5300 assert(!ClassLoaderDataGraph::contains((address)p),
5301 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5302 PTR_FORMAT, p));
5303 _copy_non_heap_obj_cl->do_oop(p);
5304 }
5305 }
5306 }
5307 };
5308
5309 // Serial drain queue closure. Called as the 'complete_gc'
5310 // closure for each discovered list in some of the
5311 // reference processing phases.
5312
5313 class G1STWDrainQueueClosure: public VoidClosure {
5314 protected:
5315 G1CollectedHeap* _g1h;
5316 G1ParScanThreadState* _par_scan_state;
5317
5318 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5319
5320 public:
5321 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5322 _g1h(g1h),
5323 _par_scan_state(pss)
5324 { }
5325
5326 void do_void() {
5327 G1ParScanThreadState* const pss = par_scan_state();
5328 pss->trim_queue();
5329 }
5330 };
5331
5332 // Parallel Reference Processing closures
5333
5334 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5335 // processing during G1 evacuation pauses.
5336
5337 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5338 private:
5339 G1CollectedHeap* _g1h;
5340 RefToScanQueueSet* _queues;
5341 FlexibleWorkGang* _workers;
5342 int _active_workers;
5343
5344 public:
5345 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5346 FlexibleWorkGang* workers,
5347 RefToScanQueueSet *task_queues,
5348 int n_workers) :
5349 _g1h(g1h),
5350 _queues(task_queues),
5351 _workers(workers),
5352 _active_workers(n_workers)
5353 {
5354 assert(n_workers > 0, "shouldn't call this otherwise");
5355 }
5356
5357 // Executes the given task using concurrent marking worker threads.
5358 virtual void execute(ProcessTask& task);
5359 virtual void execute(EnqueueTask& task);
5360 };
5361
5362 // Gang task for possibly parallel reference processing
5363
5364 class G1STWRefProcTaskProxy: public AbstractGangTask {
5365 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5366 ProcessTask& _proc_task;
5367 G1CollectedHeap* _g1h;
5368 RefToScanQueueSet *_task_queues;
5369 ParallelTaskTerminator* _terminator;
5370
5371 public:
5372 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5373 G1CollectedHeap* g1h,
5374 RefToScanQueueSet *task_queues,
5375 ParallelTaskTerminator* terminator) :
5376 AbstractGangTask("Process reference objects in parallel"),
5377 _proc_task(proc_task),
5378 _g1h(g1h),
5379 _task_queues(task_queues),
5380 _terminator(terminator)
5381 {}
5382
5383 virtual void work(uint worker_id) {
5384 // The reference processing task executed by a single worker.
5385 ResourceMark rm;
5386 HandleMark hm;
5387
5388 G1STWIsAliveClosure is_alive(_g1h);
5389
5390 G1ParScanThreadState pss(_g1h, worker_id);
5391
5392 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5393 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5394 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5395
5396 pss.set_evac_closure(&scan_evac_cl);
5397 pss.set_evac_failure_closure(&evac_failure_cl);
5398 pss.set_partial_scan_closure(&partial_scan_cl);
5399
5400 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5401 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5402
5403 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5404 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5405
5406 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5407 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5408
5409 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5410 // We also need to mark copied objects.
5411 copy_non_heap_cl = ©_mark_non_heap_cl;
5412 copy_metadata_cl = ©_mark_metadata_cl;
5413 }
5414
5415 // Keep alive closure.
5416 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5417
5418 // Complete GC closure
5419 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5420
5421 // Call the reference processing task's work routine.
5422 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5423
5424 // Note we cannot assert that the refs array is empty here as not all
5425 // of the processing tasks (specifically phase2 - pp2_work) execute
5426 // the complete_gc closure (which ordinarily would drain the queue) so
5427 // the queue may not be empty.
5428 }
5429 };
5430
5431 // Driver routine for parallel reference processing.
5432 // Creates an instance of the ref processing gang
5433 // task and has the worker threads execute it.
5434 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5435 assert(_workers != NULL, "Need parallel worker threads.");
5436
5437 ParallelTaskTerminator terminator(_active_workers, _queues);
5438 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5439
5440 _g1h->set_par_threads(_active_workers);
5441 _workers->run_task(&proc_task_proxy);
5442 _g1h->set_par_threads(0);
5443 }
5444
5445 // Gang task for parallel reference enqueueing.
5446
5447 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5448 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5449 EnqueueTask& _enq_task;
5450
5451 public:
5452 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5453 AbstractGangTask("Enqueue reference objects in parallel"),
5454 _enq_task(enq_task)
5455 { }
5456
5457 virtual void work(uint worker_id) {
5458 _enq_task.work(worker_id);
5459 }
5460 };
5461
5462 // Driver routine for parallel reference enqueueing.
5463 // Creates an instance of the ref enqueueing gang
5464 // task and has the worker threads execute it.
5465
5466 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5467 assert(_workers != NULL, "Need parallel worker threads.");
5468
5469 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5470
5471 _g1h->set_par_threads(_active_workers);
5472 _workers->run_task(&enq_task_proxy);
5473 _g1h->set_par_threads(0);
5474 }
5475
5476 // End of weak reference support closures
5477
5478 // Abstract task used to preserve (i.e. copy) any referent objects
5479 // that are in the collection set and are pointed to by reference
5480 // objects discovered by the CM ref processor.
5481
5482 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5483 protected:
5484 G1CollectedHeap* _g1h;
5485 RefToScanQueueSet *_queues;
5486 ParallelTaskTerminator _terminator;
5487 uint _n_workers;
5488
5489 public:
5490 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5491 AbstractGangTask("ParPreserveCMReferents"),
5492 _g1h(g1h),
5493 _queues(task_queues),
5494 _terminator(workers, _queues),
5495 _n_workers(workers)
5496 { }
5497
5498 void work(uint worker_id) {
5499 ResourceMark rm;
5500 HandleMark hm;
5501
5502 G1ParScanThreadState pss(_g1h, worker_id);
5503 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5504 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5505 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5506
5507 pss.set_evac_closure(&scan_evac_cl);
5508 pss.set_evac_failure_closure(&evac_failure_cl);
5509 pss.set_partial_scan_closure(&partial_scan_cl);
5510
5511 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5512
5513
5514 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5515 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5516
5517 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5518 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5519
5520 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5521 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5522
5523 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5524 // We also need to mark copied objects.
5525 copy_non_heap_cl = ©_mark_non_heap_cl;
5526 copy_metadata_cl = ©_mark_metadata_cl;
5527 }
5528
5529 // Is alive closure
5530 G1AlwaysAliveClosure always_alive(_g1h);
5531
5532 // Copying keep alive closure. Applied to referent objects that need
5533 // to be copied.
5534 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5535
5536 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5537
5538 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5539 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5540
5541 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5542 // So this must be true - but assert just in case someone decides to
5543 // change the worker ids.
5544 assert(0 <= worker_id && worker_id < limit, "sanity");
5545 assert(!rp->discovery_is_atomic(), "check this code");
5546
5547 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5548 for (uint idx = worker_id; idx < limit; idx += stride) {
5549 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5550
5551 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5552 while (iter.has_next()) {
5553 // Since discovery is not atomic for the CM ref processor, we
5554 // can see some null referent objects.
5555 iter.load_ptrs(DEBUG_ONLY(true));
5556 oop ref = iter.obj();
5557
5558 // This will filter nulls.
5559 if (iter.is_referent_alive()) {
5560 iter.make_referent_alive();
5561 }
5562 iter.move_to_next();
5563 }
5564 }
5565
5566 // Drain the queue - which may cause stealing
5567 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5568 drain_queue.do_void();
5569 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5570 assert(pss.refs()->is_empty(), "should be");
5571 }
5572 };
5573
5574 // Weak Reference processing during an evacuation pause (part 1).
5575 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5576 double ref_proc_start = os::elapsedTime();
5577
5578 ReferenceProcessor* rp = _ref_processor_stw;
5579 assert(rp->discovery_enabled(), "should have been enabled");
5580
5581 // Any reference objects, in the collection set, that were 'discovered'
5582 // by the CM ref processor should have already been copied (either by
5583 // applying the external root copy closure to the discovered lists, or
5584 // by following an RSet entry).
5585 //
5586 // But some of the referents, that are in the collection set, that these
5587 // reference objects point to may not have been copied: the STW ref
5588 // processor would have seen that the reference object had already
5589 // been 'discovered' and would have skipped discovering the reference,
5590 // but would not have treated the reference object as a regular oop.
5591 // As a result the copy closure would not have been applied to the
5592 // referent object.
5593 //
5594 // We need to explicitly copy these referent objects - the references
5595 // will be processed at the end of remarking.
5596 //
5597 // We also need to do this copying before we process the reference
5598 // objects discovered by the STW ref processor in case one of these
5599 // referents points to another object which is also referenced by an
5600 // object discovered by the STW ref processor.
5601
5602 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5603 no_of_gc_workers == workers()->active_workers(),
5604 "Need to reset active GC workers");
5605
5606 set_par_threads(no_of_gc_workers);
5607 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5608 no_of_gc_workers,
5609 _task_queues);
5610
5611 if (G1CollectedHeap::use_parallel_gc_threads()) {
5612 workers()->run_task(&keep_cm_referents);
5613 } else {
5614 keep_cm_referents.work(0);
5615 }
5616
5617 set_par_threads(0);
5618
5619 // Closure to test whether a referent is alive.
5620 G1STWIsAliveClosure is_alive(this);
5621
5622 // Even when parallel reference processing is enabled, the processing
5623 // of JNI refs is serial and performed serially by the current thread
5624 // rather than by a worker. The following PSS will be used for processing
5625 // JNI refs.
5626
5627 // Use only a single queue for this PSS.
5628 G1ParScanThreadState pss(this, 0);
5629
5630 // We do not embed a reference processor in the copying/scanning
5631 // closures while we're actually processing the discovered
5632 // reference objects.
5633 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5634 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5635 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5636
5637 pss.set_evac_closure(&scan_evac_cl);
5638 pss.set_evac_failure_closure(&evac_failure_cl);
5639 pss.set_partial_scan_closure(&partial_scan_cl);
5640
5641 assert(pss.refs()->is_empty(), "pre-condition");
5642
5643 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5644 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5645
5646 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5647 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5648
5649 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5650 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5651
5652 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5653 // We also need to mark copied objects.
5654 copy_non_heap_cl = ©_mark_non_heap_cl;
5655 copy_metadata_cl = ©_mark_metadata_cl;
5656 }
5657
5658 // Keep alive closure.
5659 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5660
5661 // Serial Complete GC closure
5662 G1STWDrainQueueClosure drain_queue(this, &pss);
5663
5664 // Setup the soft refs policy...
5665 rp->setup_policy(false);
5666
5667 ReferenceProcessorStats stats;
5668 if (!rp->processing_is_mt()) {
5669 // Serial reference processing...
5670 stats = rp->process_discovered_references(&is_alive,
5671 &keep_alive,
5672 &drain_queue,
5673 NULL,
5674 _gc_timer_stw);
5675 } else {
5676 // Parallel reference processing
5677 assert(rp->num_q() == no_of_gc_workers, "sanity");
5678 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5679
5680 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5681 stats = rp->process_discovered_references(&is_alive,
5682 &keep_alive,
5683 &drain_queue,
5684 &par_task_executor,
5685 _gc_timer_stw);
5686 }
5687
5688 _gc_tracer_stw->report_gc_reference_stats(stats);
5689 // We have completed copying any necessary live referent objects
5690 // (that were not copied during the actual pause) so we can
5691 // retire any active alloc buffers
5692 pss.retire_alloc_buffers();
5693 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5694
5695 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5696 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5697 }
5698
5699 // Weak Reference processing during an evacuation pause (part 2).
5700 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5701 double ref_enq_start = os::elapsedTime();
5702
5703 ReferenceProcessor* rp = _ref_processor_stw;
5704 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5705
5706 // Now enqueue any remaining on the discovered lists on to
5707 // the pending list.
5708 if (!rp->processing_is_mt()) {
5709 // Serial reference processing...
5710 rp->enqueue_discovered_references();
5711 } else {
5712 // Parallel reference enqueueing
5713
5714 assert(no_of_gc_workers == workers()->active_workers(),
5715 "Need to reset active workers");
5716 assert(rp->num_q() == no_of_gc_workers, "sanity");
5717 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5718
5719 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5720 rp->enqueue_discovered_references(&par_task_executor);
5721 }
5722
5723 rp->verify_no_references_recorded();
5724 assert(!rp->discovery_enabled(), "should have been disabled");
5725
5726 // FIXME
5727 // CM's reference processing also cleans up the string and symbol tables.
5728 // Should we do that here also? We could, but it is a serial operation
5729 // and could significantly increase the pause time.
5730
5731 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5732 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5733 }
5734
5735 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5736 _expand_heap_after_alloc_failure = true;
5737 _evacuation_failed = false;
5738
5739 // Should G1EvacuationFailureALot be in effect for this GC?
5740 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5741
5742 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5743
5744 // Disable the hot card cache.
5745 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5746 hot_card_cache->reset_hot_cache_claimed_index();
5747 hot_card_cache->set_use_cache(false);
5748
5749 uint n_workers;
5750 if (G1CollectedHeap::use_parallel_gc_threads()) {
5751 n_workers =
5752 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5753 workers()->active_workers(),
5754 Threads::number_of_non_daemon_threads());
5755 assert(UseDynamicNumberOfGCThreads ||
5756 n_workers == workers()->total_workers(),
5757 "If not dynamic should be using all the workers");
5758 workers()->set_active_workers(n_workers);
5759 set_par_threads(n_workers);
5760 } else {
5761 assert(n_par_threads() == 0,
5762 "Should be the original non-parallel value");
5763 n_workers = 1;
5764 }
5765
5766 G1ParTask g1_par_task(this, _task_queues);
5767
5768 init_for_evac_failure(NULL);
5769
5770 rem_set()->prepare_for_younger_refs_iterate(true);
5771
5772 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5773 double start_par_time_sec = os::elapsedTime();
5774 double end_par_time_sec;
5775
5776 {
5777 StrongRootsScope srs(this);
5778
5779 if (G1CollectedHeap::use_parallel_gc_threads()) {
5780 // The individual threads will set their evac-failure closures.
5781 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5782 // These tasks use ShareHeap::_process_strong_tasks
5783 assert(UseDynamicNumberOfGCThreads ||
5784 workers()->active_workers() == workers()->total_workers(),
5785 "If not dynamic should be using all the workers");
5786 workers()->run_task(&g1_par_task);
5787 } else {
5788 g1_par_task.set_for_termination(n_workers);
5789 g1_par_task.work(0);
5790 }
5791 end_par_time_sec = os::elapsedTime();
5792
5793 // Closing the inner scope will execute the destructor
5794 // for the StrongRootsScope object. We record the current
5795 // elapsed time before closing the scope so that time
5796 // taken for the SRS destructor is NOT included in the
5797 // reported parallel time.
5798 }
5799
5800 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5801 g1_policy()->phase_times()->record_par_time(par_time_ms);
5802
5803 double code_root_fixup_time_ms =
5804 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5805 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5806
5807 set_par_threads(0);
5808
5809 // Process any discovered reference objects - we have
5810 // to do this _before_ we retire the GC alloc regions
5811 // as we may have to copy some 'reachable' referent
5812 // objects (and their reachable sub-graphs) that were
5813 // not copied during the pause.
5814 process_discovered_references(n_workers);
5815
5816 // Weak root processing.
5817 {
5818 G1STWIsAliveClosure is_alive(this);
5819 G1KeepAliveClosure keep_alive(this);
5820 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5821 }
5822
5823 release_gc_alloc_regions(n_workers, evacuation_info);
5824 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5825
5826 // Reset and re-enable the hot card cache.
5827 // Note the counts for the cards in the regions in the
5828 // collection set are reset when the collection set is freed.
5829 hot_card_cache->reset_hot_cache();
5830 hot_card_cache->set_use_cache(true);
5831
5832 // Migrate the strong code roots attached to each region in
5833 // the collection set. Ideally we would like to do this
5834 // after we have finished the scanning/evacuation of the
5835 // strong code roots for a particular heap region.
5836 migrate_strong_code_roots();
5837
5838 if (g1_policy()->during_initial_mark_pause()) {
5839 // Reset the claim values set during marking the strong code roots
5840 reset_heap_region_claim_values();
5841 }
5842
5843 finalize_for_evac_failure();
5844
5845 if (evacuation_failed()) {
5846 remove_self_forwarding_pointers();
5847
5848 // Reset the G1EvacuationFailureALot counters and flags
5849 // Note: the values are reset only when an actual
5850 // evacuation failure occurs.
5851 NOT_PRODUCT(reset_evacuation_should_fail();)
5852 }
5853
5854 // Enqueue any remaining references remaining on the STW
5855 // reference processor's discovered lists. We need to do
5856 // this after the card table is cleaned (and verified) as
5857 // the act of enqueueing entries on to the pending list
5858 // will log these updates (and dirty their associated
5859 // cards). We need these updates logged to update any
5860 // RSets.
5861 enqueue_discovered_references(n_workers);
5862
5863 if (G1DeferredRSUpdate) {
5864 RedirtyLoggedCardTableEntryFastClosure redirty;
5865 dirty_card_queue_set().set_closure(&redirty);
5866 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5867
5868 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5869 dcq.merge_bufferlists(&dirty_card_queue_set());
5870 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5871 }
5872 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5873 }
5874
5875 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5876 size_t* pre_used,
5877 FreeRegionList* free_list,
5878 OldRegionSet* old_proxy_set,
5879 HumongousRegionSet* humongous_proxy_set,
5880 HRRSCleanupTask* hrrs_cleanup_task,
5881 bool par) {
5882 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5883 if (hr->isHumongous()) {
5884 assert(hr->startsHumongous(), "we should only see starts humongous");
5885 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5886 } else {
5887 _old_set.remove_with_proxy(hr, old_proxy_set);
5888 free_region(hr, pre_used, free_list, par);
5889 }
5890 } else {
5891 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5892 }
5893 }
5894
5895 void G1CollectedHeap::free_region(HeapRegion* hr,
5896 size_t* pre_used,
5897 FreeRegionList* free_list,
5898 bool par) {
5899 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5900 assert(!hr->is_empty(), "the region should not be empty");
5901 assert(free_list != NULL, "pre-condition");
5902
5903 // Clear the card counts for this region.
5904 // Note: we only need to do this if the region is not young
5905 // (since we don't refine cards in young regions).
5906 if (!hr->is_young()) {
5907 _cg1r->hot_card_cache()->reset_card_counts(hr);
5908 }
5909 *pre_used += hr->used();
5910 hr->hr_clear(par, true /* clear_space */);
5911 free_list->add_as_head(hr);
5912 }
5913
5914 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5915 size_t* pre_used,
5916 FreeRegionList* free_list,
5917 HumongousRegionSet* humongous_proxy_set,
5918 bool par) {
5919 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5920 assert(free_list != NULL, "pre-condition");
5921 assert(humongous_proxy_set != NULL, "pre-condition");
5922
5923 size_t hr_used = hr->used();
5924 size_t hr_capacity = hr->capacity();
5925 size_t hr_pre_used = 0;
5926 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5927 // We need to read this before we make the region non-humongous,
5928 // otherwise the information will be gone.
5929 uint last_index = hr->last_hc_index();
5930 hr->set_notHumongous();
5931 free_region(hr, &hr_pre_used, free_list, par);
5932
5933 uint i = hr->hrs_index() + 1;
5934 while (i < last_index) {
5935 HeapRegion* curr_hr = region_at(i);
5936 assert(curr_hr->continuesHumongous(), "invariant");
5937 curr_hr->set_notHumongous();
5938 free_region(curr_hr, &hr_pre_used, free_list, par);
5939 i += 1;
5940 }
5941 assert(hr_pre_used == hr_used,
5942 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5943 "should be the same", hr_pre_used, hr_used));
5944 *pre_used += hr_pre_used;
5945 }
5946
5947 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5948 FreeRegionList* free_list,
5949 OldRegionSet* old_proxy_set,
5950 HumongousRegionSet* humongous_proxy_set,
5951 bool par) {
5952 if (pre_used > 0) {
5953 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5954 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5955 assert(_summary_bytes_used >= pre_used,
5956 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5957 "should be >= pre_used: "SIZE_FORMAT,
5958 _summary_bytes_used, pre_used));
5959 _summary_bytes_used -= pre_used;
5960 }
5961 if (free_list != NULL && !free_list->is_empty()) {
5962 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5963 _free_list.add_as_head(free_list);
5964 }
5965 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5966 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5967 _old_set.update_from_proxy(old_proxy_set);
5968 }
5969 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5970 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5971 _humongous_set.update_from_proxy(humongous_proxy_set);
5972 }
5973 }
5974
5975 class G1ParCleanupCTTask : public AbstractGangTask {
5976 G1SATBCardTableModRefBS* _ct_bs;
5977 G1CollectedHeap* _g1h;
5978 HeapRegion* volatile _su_head;
5979 public:
5980 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5981 G1CollectedHeap* g1h) :
5982 AbstractGangTask("G1 Par Cleanup CT Task"),
5983 _ct_bs(ct_bs), _g1h(g1h) { }
5984
5985 void work(uint worker_id) {
5986 HeapRegion* r;
5987 while (r = _g1h->pop_dirty_cards_region()) {
5988 clear_cards(r);
5989 }
5990 }
5991
5992 void clear_cards(HeapRegion* r) {
5993 // Cards of the survivors should have already been dirtied.
5994 if (!r->is_survivor()) {
5995 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5996 }
5997 }
5998 };
5999
6000 #ifndef PRODUCT
6001 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6002 G1CollectedHeap* _g1h;
6003 G1SATBCardTableModRefBS* _ct_bs;
6004 public:
6005 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6006 : _g1h(g1h), _ct_bs(ct_bs) { }
6007 virtual bool doHeapRegion(HeapRegion* r) {
6008 if (r->is_survivor()) {
6009 _g1h->verify_dirty_region(r);
6010 } else {
6011 _g1h->verify_not_dirty_region(r);
6012 }
6013 return false;
6014 }
6015 };
6016
6017 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6018 // All of the region should be clean.
6019 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6020 MemRegion mr(hr->bottom(), hr->end());
6021 ct_bs->verify_not_dirty_region(mr);
6022 }
6023
6024 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6025 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6026 // dirty allocated blocks as they allocate them. The thread that
6027 // retires each region and replaces it with a new one will do a
6028 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6029 // not dirty that area (one less thing to have to do while holding
6030 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6031 // is dirty.
6032 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6033 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6034 if (hr->is_young()) {
6035 ct_bs->verify_g1_young_region(mr);
6036 } else {
6037 ct_bs->verify_dirty_region(mr);
6038 }
6039 }
6040
6041 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6042 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6043 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6044 verify_dirty_region(hr);
6045 }
6046 }
6047
6048 void G1CollectedHeap::verify_dirty_young_regions() {
6049 verify_dirty_young_list(_young_list->first_region());
6050 }
6051 #endif
6052
6053 void G1CollectedHeap::cleanUpCardTable() {
6054 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6055 double start = os::elapsedTime();
6056
6057 {
6058 // Iterate over the dirty cards region list.
6059 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6060
6061 if (G1CollectedHeap::use_parallel_gc_threads()) {
6062 set_par_threads();
6063 workers()->run_task(&cleanup_task);
6064 set_par_threads(0);
6065 } else {
6066 while (_dirty_cards_region_list) {
6067 HeapRegion* r = _dirty_cards_region_list;
6068 cleanup_task.clear_cards(r);
6069 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6070 if (_dirty_cards_region_list == r) {
6071 // The last region.
6072 _dirty_cards_region_list = NULL;
6073 }
6074 r->set_next_dirty_cards_region(NULL);
6075 }
6076 }
6077 #ifndef PRODUCT
6078 if (G1VerifyCTCleanup || VerifyAfterGC) {
6079 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6080 heap_region_iterate(&cleanup_verifier);
6081 }
6082 #endif
6083 }
6084
6085 double elapsed = os::elapsedTime() - start;
6086 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6087 }
6088
6089 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6090 size_t pre_used = 0;
6091 FreeRegionList local_free_list("Local List for CSet Freeing");
6092
6093 double young_time_ms = 0.0;
6094 double non_young_time_ms = 0.0;
6095
6096 // Since the collection set is a superset of the the young list,
6097 // all we need to do to clear the young list is clear its
6098 // head and length, and unlink any young regions in the code below
6099 _young_list->clear();
6100
6101 G1CollectorPolicy* policy = g1_policy();
6102
6103 double start_sec = os::elapsedTime();
6104 bool non_young = true;
6105
6106 HeapRegion* cur = cs_head;
6107 int age_bound = -1;
6108 size_t rs_lengths = 0;
6109
6110 while (cur != NULL) {
6111 assert(!is_on_master_free_list(cur), "sanity");
6112 if (non_young) {
6113 if (cur->is_young()) {
6114 double end_sec = os::elapsedTime();
6115 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6116 non_young_time_ms += elapsed_ms;
6117
6118 start_sec = os::elapsedTime();
6119 non_young = false;
6120 }
6121 } else {
6122 if (!cur->is_young()) {
6123 double end_sec = os::elapsedTime();
6124 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6125 young_time_ms += elapsed_ms;
6126
6127 start_sec = os::elapsedTime();
6128 non_young = true;
6129 }
6130 }
6131
6132 rs_lengths += cur->rem_set()->occupied();
6133
6134 HeapRegion* next = cur->next_in_collection_set();
6135 assert(cur->in_collection_set(), "bad CS");
6136 cur->set_next_in_collection_set(NULL);
6137 cur->set_in_collection_set(false);
6138
6139 if (cur->is_young()) {
6140 int index = cur->young_index_in_cset();
6141 assert(index != -1, "invariant");
6142 assert((uint) index < policy->young_cset_region_length(), "invariant");
6143 size_t words_survived = _surviving_young_words[index];
6144 cur->record_surv_words_in_group(words_survived);
6145
6146 // At this point the we have 'popped' cur from the collection set
6147 // (linked via next_in_collection_set()) but it is still in the
6148 // young list (linked via next_young_region()). Clear the
6149 // _next_young_region field.
6150 cur->set_next_young_region(NULL);
6151 } else {
6152 int index = cur->young_index_in_cset();
6153 assert(index == -1, "invariant");
6154 }
6155
6156 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6157 (!cur->is_young() && cur->young_index_in_cset() == -1),
6158 "invariant" );
6159
6160 if (!cur->evacuation_failed()) {
6161 MemRegion used_mr = cur->used_region();
6162
6163 // And the region is empty.
6164 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6165 free_region(cur, &pre_used, &local_free_list, false /* par */);
6166 } else {
6167 cur->uninstall_surv_rate_group();
6168 if (cur->is_young()) {
6169 cur->set_young_index_in_cset(-1);
6170 }
6171 cur->set_not_young();
6172 cur->set_evacuation_failed(false);
6173 // The region is now considered to be old.
6174 _old_set.add(cur);
6175 evacuation_info.increment_collectionset_used_after(cur->used());
6176 }
6177 cur = next;
6178 }
6179
6180 evacuation_info.set_regions_freed(local_free_list.length());
6181 policy->record_max_rs_lengths(rs_lengths);
6182 policy->cset_regions_freed();
6183
6184 double end_sec = os::elapsedTime();
6185 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6186
6187 if (non_young) {
6188 non_young_time_ms += elapsed_ms;
6189 } else {
6190 young_time_ms += elapsed_ms;
6191 }
6192
6193 update_sets_after_freeing_regions(pre_used, &local_free_list,
6194 NULL /* old_proxy_set */,
6195 NULL /* humongous_proxy_set */,
6196 false /* par */);
6197 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6198 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6199 }
6200
6201 // This routine is similar to the above but does not record
6202 // any policy statistics or update free lists; we are abandoning
6203 // the current incremental collection set in preparation of a
6204 // full collection. After the full GC we will start to build up
6205 // the incremental collection set again.
6206 // This is only called when we're doing a full collection
6207 // and is immediately followed by the tearing down of the young list.
6208
6209 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6210 HeapRegion* cur = cs_head;
6211
6212 while (cur != NULL) {
6213 HeapRegion* next = cur->next_in_collection_set();
6214 assert(cur->in_collection_set(), "bad CS");
6215 cur->set_next_in_collection_set(NULL);
6216 cur->set_in_collection_set(false);
6217 cur->set_young_index_in_cset(-1);
6218 cur = next;
6219 }
6220 }
6221
6222 void G1CollectedHeap::set_free_regions_coming() {
6223 if (G1ConcRegionFreeingVerbose) {
6224 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6225 "setting free regions coming");
6226 }
6227
6228 assert(!free_regions_coming(), "pre-condition");
6229 _free_regions_coming = true;
6230 }
6231
6232 void G1CollectedHeap::reset_free_regions_coming() {
6233 assert(free_regions_coming(), "pre-condition");
6234
6235 {
6236 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6237 _free_regions_coming = false;
6238 SecondaryFreeList_lock->notify_all();
6239 }
6240
6241 if (G1ConcRegionFreeingVerbose) {
6242 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6243 "reset free regions coming");
6244 }
6245 }
6246
6247 void G1CollectedHeap::wait_while_free_regions_coming() {
6248 // Most of the time we won't have to wait, so let's do a quick test
6249 // first before we take the lock.
6250 if (!free_regions_coming()) {
6251 return;
6252 }
6253
6254 if (G1ConcRegionFreeingVerbose) {
6255 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6256 "waiting for free regions");
6257 }
6258
6259 {
6260 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6261 while (free_regions_coming()) {
6262 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6263 }
6264 }
6265
6266 if (G1ConcRegionFreeingVerbose) {
6267 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6268 "done waiting for free regions");
6269 }
6270 }
6271
6272 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6273 assert(heap_lock_held_for_gc(),
6274 "the heap lock should already be held by or for this thread");
6275 _young_list->push_region(hr);
6276 }
6277
6278 class NoYoungRegionsClosure: public HeapRegionClosure {
6279 private:
6280 bool _success;
6281 public:
6282 NoYoungRegionsClosure() : _success(true) { }
6283 bool doHeapRegion(HeapRegion* r) {
6284 if (r->is_young()) {
6285 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6286 r->bottom(), r->end());
6287 _success = false;
6288 }
6289 return false;
6290 }
6291 bool success() { return _success; }
6292 };
6293
6294 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6295 bool ret = _young_list->check_list_empty(check_sample);
6296
6297 if (check_heap) {
6298 NoYoungRegionsClosure closure;
6299 heap_region_iterate(&closure);
6300 ret = ret && closure.success();
6301 }
6302
6303 return ret;
6304 }
6305
6306 class TearDownRegionSetsClosure : public HeapRegionClosure {
6307 private:
6308 OldRegionSet *_old_set;
6309
6310 public:
6311 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6312
6313 bool doHeapRegion(HeapRegion* r) {
6314 if (r->is_empty()) {
6315 // We ignore empty regions, we'll empty the free list afterwards
6316 } else if (r->is_young()) {
6317 // We ignore young regions, we'll empty the young list afterwards
6318 } else if (r->isHumongous()) {
6319 // We ignore humongous regions, we're not tearing down the
6320 // humongous region set
6321 } else {
6322 // The rest should be old
6323 _old_set->remove(r);
6324 }
6325 return false;
6326 }
6327
6328 ~TearDownRegionSetsClosure() {
6329 assert(_old_set->is_empty(), "post-condition");
6330 }
6331 };
6332
6333 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6334 assert_at_safepoint(true /* should_be_vm_thread */);
6335
6336 if (!free_list_only) {
6337 TearDownRegionSetsClosure cl(&_old_set);
6338 heap_region_iterate(&cl);
6339
6340 // Need to do this after the heap iteration to be able to
6341 // recognize the young regions and ignore them during the iteration.
6342 _young_list->empty_list();
6343 }
6344 _free_list.remove_all();
6345 }
6346
6347 class RebuildRegionSetsClosure : public HeapRegionClosure {
6348 private:
6349 bool _free_list_only;
6350 OldRegionSet* _old_set;
6351 FreeRegionList* _free_list;
6352 size_t _total_used;
6353
6354 public:
6355 RebuildRegionSetsClosure(bool free_list_only,
6356 OldRegionSet* old_set, FreeRegionList* free_list) :
6357 _free_list_only(free_list_only),
6358 _old_set(old_set), _free_list(free_list), _total_used(0) {
6359 assert(_free_list->is_empty(), "pre-condition");
6360 if (!free_list_only) {
6361 assert(_old_set->is_empty(), "pre-condition");
6362 }
6363 }
6364
6365 bool doHeapRegion(HeapRegion* r) {
6366 if (r->continuesHumongous()) {
6367 return false;
6368 }
6369
6370 if (r->is_empty()) {
6371 // Add free regions to the free list
6372 _free_list->add_as_tail(r);
6373 } else if (!_free_list_only) {
6374 assert(!r->is_young(), "we should not come across young regions");
6375
6376 if (r->isHumongous()) {
6377 // We ignore humongous regions, we left the humongous set unchanged
6378 } else {
6379 // The rest should be old, add them to the old set
6380 _old_set->add(r);
6381 }
6382 _total_used += r->used();
6383 }
6384
6385 return false;
6386 }
6387
6388 size_t total_used() {
6389 return _total_used;
6390 }
6391 };
6392
6393 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6394 assert_at_safepoint(true /* should_be_vm_thread */);
6395
6396 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6397 heap_region_iterate(&cl);
6398
6399 if (!free_list_only) {
6400 _summary_bytes_used = cl.total_used();
6401 }
6402 assert(_summary_bytes_used == recalculate_used(),
6403 err_msg("inconsistent _summary_bytes_used, "
6404 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6405 _summary_bytes_used, recalculate_used()));
6406 }
6407
6408 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6409 _refine_cte_cl->set_concurrent(concurrent);
6410 }
6411
6412 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6413 HeapRegion* hr = heap_region_containing(p);
6414 if (hr == NULL) {
6415 return false;
6416 } else {
6417 return hr->is_in(p);
6418 }
6419 }
6420
6421 // Methods for the mutator alloc region
6422
6423 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6424 bool force) {
6425 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6426 assert(!force || g1_policy()->can_expand_young_list(),
6427 "if force is true we should be able to expand the young list");
6428 bool young_list_full = g1_policy()->is_young_list_full();
6429 if (force || !young_list_full) {
6430 HeapRegion* new_alloc_region = new_region(word_size,
6431 false /* do_expand */);
6432 if (new_alloc_region != NULL) {
6433 set_region_short_lived_locked(new_alloc_region);
6434 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6435 return new_alloc_region;
6436 }
6437 }
6438 return NULL;
6439 }
6440
6441 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6442 size_t allocated_bytes) {
6443 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6444 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6445
6446 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6447 _summary_bytes_used += allocated_bytes;
6448 _hr_printer.retire(alloc_region);
6449 // We update the eden sizes here, when the region is retired,
6450 // instead of when it's allocated, since this is the point that its
6451 // used space has been recored in _summary_bytes_used.
6452 g1mm()->update_eden_size();
6453 }
6454
6455 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6456 bool force) {
6457 return _g1h->new_mutator_alloc_region(word_size, force);
6458 }
6459
6460 void G1CollectedHeap::set_par_threads() {
6461 // Don't change the number of workers. Use the value previously set
6462 // in the workgroup.
6463 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6464 uint n_workers = workers()->active_workers();
6465 assert(UseDynamicNumberOfGCThreads ||
6466 n_workers == workers()->total_workers(),
6467 "Otherwise should be using the total number of workers");
6468 if (n_workers == 0) {
6469 assert(false, "Should have been set in prior evacuation pause.");
6470 n_workers = ParallelGCThreads;
6471 workers()->set_active_workers(n_workers);
6472 }
6473 set_par_threads(n_workers);
6474 }
6475
6476 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6477 size_t allocated_bytes) {
6478 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6479 }
6480
6481 // Methods for the GC alloc regions
6482
6483 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6484 uint count,
6485 GCAllocPurpose ap) {
6486 assert(FreeList_lock->owned_by_self(), "pre-condition");
6487
6488 if (count < g1_policy()->max_regions(ap)) {
6489 HeapRegion* new_alloc_region = new_region(word_size,
6490 true /* do_expand */);
6491 if (new_alloc_region != NULL) {
6492 // We really only need to do this for old regions given that we
6493 // should never scan survivors. But it doesn't hurt to do it
6494 // for survivors too.
6495 new_alloc_region->set_saved_mark();
6496 if (ap == GCAllocForSurvived) {
6497 new_alloc_region->set_survivor();
6498 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6499 } else {
6500 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6501 }
6502 bool during_im = g1_policy()->during_initial_mark_pause();
6503 new_alloc_region->note_start_of_copying(during_im);
6504 return new_alloc_region;
6505 } else {
6506 g1_policy()->note_alloc_region_limit_reached(ap);
6507 }
6508 }
6509 return NULL;
6510 }
6511
6512 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6513 size_t allocated_bytes,
6514 GCAllocPurpose ap) {
6515 bool during_im = g1_policy()->during_initial_mark_pause();
6516 alloc_region->note_end_of_copying(during_im);
6517 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6518 if (ap == GCAllocForSurvived) {
6519 young_list()->add_survivor_region(alloc_region);
6520 } else {
6521 _old_set.add(alloc_region);
6522 }
6523 _hr_printer.retire(alloc_region);
6524 }
6525
6526 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6527 bool force) {
6528 assert(!force, "not supported for GC alloc regions");
6529 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6530 }
6531
6532 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6533 size_t allocated_bytes) {
6534 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6535 GCAllocForSurvived);
6536 }
6537
6538 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6539 bool force) {
6540 assert(!force, "not supported for GC alloc regions");
6541 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6542 }
6543
6544 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6545 size_t allocated_bytes) {
6546 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6547 GCAllocForTenured);
6548 }
6549 // Heap region set verification
6550
6551 class VerifyRegionListsClosure : public HeapRegionClosure {
6552 private:
6553 FreeRegionList* _free_list;
6554 OldRegionSet* _old_set;
6555 HumongousRegionSet* _humongous_set;
6556 uint _region_count;
6557
6558 public:
6559 VerifyRegionListsClosure(OldRegionSet* old_set,
6560 HumongousRegionSet* humongous_set,
6561 FreeRegionList* free_list) :
6562 _old_set(old_set), _humongous_set(humongous_set),
6563 _free_list(free_list), _region_count(0) { }
6564
6565 uint region_count() { return _region_count; }
6566
6567 bool doHeapRegion(HeapRegion* hr) {
6568 _region_count += 1;
6569
6570 if (hr->continuesHumongous()) {
6571 return false;
6572 }
6573
6574 if (hr->is_young()) {
6575 // TODO
6576 } else if (hr->startsHumongous()) {
6577 _humongous_set->verify_next_region(hr);
6578 } else if (hr->is_empty()) {
6579 _free_list->verify_next_region(hr);
6580 } else {
6581 _old_set->verify_next_region(hr);
6582 }
6583 return false;
6584 }
6585 };
6586
6587 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6588 HeapWord* bottom) {
6589 HeapWord* end = bottom + HeapRegion::GrainWords;
6590 MemRegion mr(bottom, end);
6591 assert(_g1_reserved.contains(mr), "invariant");
6592 // This might return NULL if the allocation fails
6593 return new HeapRegion(hrs_index, _bot_shared, mr);
6594 }
6595
6596 void G1CollectedHeap::verify_region_sets() {
6597 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6598
6599 // First, check the explicit lists.
6600 _free_list.verify();
6601 {
6602 // Given that a concurrent operation might be adding regions to
6603 // the secondary free list we have to take the lock before
6604 // verifying it.
6605 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6606 _secondary_free_list.verify();
6607 }
6608 _old_set.verify();
6609 _humongous_set.verify();
6610
6611 // If a concurrent region freeing operation is in progress it will
6612 // be difficult to correctly attributed any free regions we come
6613 // across to the correct free list given that they might belong to
6614 // one of several (free_list, secondary_free_list, any local lists,
6615 // etc.). So, if that's the case we will skip the rest of the
6616 // verification operation. Alternatively, waiting for the concurrent
6617 // operation to complete will have a non-trivial effect on the GC's
6618 // operation (no concurrent operation will last longer than the
6619 // interval between two calls to verification) and it might hide
6620 // any issues that we would like to catch during testing.
6621 if (free_regions_coming()) {
6622 return;
6623 }
6624
6625 // Make sure we append the secondary_free_list on the free_list so
6626 // that all free regions we will come across can be safely
6627 // attributed to the free_list.
6628 append_secondary_free_list_if_not_empty_with_lock();
6629
6630 // Finally, make sure that the region accounting in the lists is
6631 // consistent with what we see in the heap.
6632 _old_set.verify_start();
6633 _humongous_set.verify_start();
6634 _free_list.verify_start();
6635
6636 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6637 heap_region_iterate(&cl);
6638
6639 _old_set.verify_end();
6640 _humongous_set.verify_end();
6641 _free_list.verify_end();
6642 }
6643
6644 // Optimized nmethod scanning
6645
6646 class RegisterNMethodOopClosure: public OopClosure {
6647 G1CollectedHeap* _g1h;
6648 nmethod* _nm;
6649
6650 template <class T> void do_oop_work(T* p) {
6651 T heap_oop = oopDesc::load_heap_oop(p);
6652 if (!oopDesc::is_null(heap_oop)) {
6653 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6654 HeapRegion* hr = _g1h->heap_region_containing(obj);
6655 assert(!hr->isHumongous(), "code root in humongous region?");
6656
6657 // HeapRegion::add_strong_code_root() avoids adding duplicate
6658 // entries but having duplicates is OK since we "mark" nmethods
6659 // as visited when we scan the strong code root lists during the GC.
6660 hr->add_strong_code_root(_nm);
6661 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), "add failed?");
6662 }
6663 }
6664
6665 public:
6666 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6667 _g1h(g1h), _nm(nm) {}
6668
6669 void do_oop(oop* p) { do_oop_work(p); }
6670 void do_oop(narrowOop* p) { do_oop_work(p); }
6671 };
6672
6673 class UnregisterNMethodOopClosure: public OopClosure {
6674 G1CollectedHeap* _g1h;
6675 nmethod* _nm;
6676
6677 template <class T> void do_oop_work(T* p) {
6678 T heap_oop = oopDesc::load_heap_oop(p);
6679 if (!oopDesc::is_null(heap_oop)) {
6680 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6681 HeapRegion* hr = _g1h->heap_region_containing(obj);
6682 assert(!hr->isHumongous(), "code root in humongous region?");
6683 hr->remove_strong_code_root(_nm);
6684 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), "remove failed?");
6685 }
6686 }
6687
6688 public:
6689 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6690 _g1h(g1h), _nm(nm) {}
6691
6692 void do_oop(oop* p) { do_oop_work(p); }
6693 void do_oop(narrowOop* p) { do_oop_work(p); }
6694 };
6695
6696 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6697 CollectedHeap::register_nmethod(nm);
6698
6699 guarantee(nm != NULL, "sanity");
6700 RegisterNMethodOopClosure reg_cl(this, nm);
6701 nm->oops_do(®_cl);
6702 }
6703
6704 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6705 CollectedHeap::unregister_nmethod(nm);
6706
6707 guarantee(nm != NULL, "sanity");
6708 UnregisterNMethodOopClosure reg_cl(this, nm);
6709 nm->oops_do(®_cl, true);
6710 }
6711
6712 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6713 public:
6714 bool doHeapRegion(HeapRegion *hr) {
6715 assert(!hr->isHumongous(), "humongous region in collection set?");
6716 hr->migrate_strong_code_roots();
6717 return false;
6718 }
6719 };
6720
6721 void G1CollectedHeap::migrate_strong_code_roots() {
6722 MigrateCodeRootsHeapRegionClosure cl;
6723 double migrate_start = os::elapsedTime();
6724 collection_set_iterate(&cl);
6725 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6726 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6727 }
6728
6729 // Mark all the code roots that point into regions *not* in the
6730 // collection set.
6731 //
6732 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6733 // walking the the code roots lists of regions not in the collection
6734 // set. Suppose we have an nmethod (M) that points to objects in two
6735 // separate regions - one in the collection set (R1) and one not (R2).
6736 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6737 // nmethod M when walking the code roots for R1. When we come to scan
6738 // the code roots for R2, we would see that M is already marked and it
6739 // would be skipped and the objects in R2 that are referenced from M
6740 // would not be evacuated.
6741
6742 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6743
6744 class MarkStrongCodeRootOopClosure: public OopClosure {
6745 ConcurrentMark* _cm;
6746 HeapRegion* _hr;
6747 uint _worker_id;
6748
6749 template <class T> void do_oop_work(T* p) {
6750 T heap_oop = oopDesc::load_heap_oop(p);
6751 if (!oopDesc::is_null(heap_oop)) {
6752 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6753 // Only mark objects in the region (which is assumed
6754 // to be not in the collection set).
6755 if (_hr->is_in(obj)) {
6756 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6757 }
6758 }
6759 }
6760
6761 public:
6762 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6763 _cm(cm), _hr(hr), _worker_id(worker_id) {
6764 assert(!_hr->in_collection_set(), "sanity");
6765 }
6766
6767 void do_oop(narrowOop* p) { do_oop_work(p); }
6768 void do_oop(oop* p) { do_oop_work(p); }
6769 };
6770
6771 MarkStrongCodeRootOopClosure _oop_cl;
6772
6773 public:
6774 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6775 _oop_cl(cm, hr, worker_id) {}
6776
6777 void do_code_blob(CodeBlob* cb) {
6778 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6779 if (nm != NULL) {
6780 nm->oops_do(&_oop_cl);
6781 }
6782 }
6783 };
6784
6785 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6786 G1CollectedHeap* _g1h;
6787 uint _worker_id;
6788
6789 public:
6790 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6791 _g1h(g1h), _worker_id(worker_id) {}
6792
6793 bool doHeapRegion(HeapRegion *hr) {
6794 HeapRegionRemSet* hrrs = hr->rem_set();
6795 if (hr->isHumongous()) {
6796 // Code roots should never be attached to a humongous region
6797 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
6798 return false;
6799 }
6800
6801 if (hr->in_collection_set()) {
6802 // Don't mark code roots into regions in the collection set here.
6803 // They will be marked when we scan them.
6804 return false;
6805 }
6806
6807 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6808 hr->strong_code_roots_do(&cb_cl);
6809 return false;
6810 }
6811 };
6812
6813 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6814 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6815 if (G1CollectedHeap::use_parallel_gc_threads()) {
6816 heap_region_par_iterate_chunked(&cl,
6817 worker_id,
6818 workers()->active_workers(),
6819 HeapRegion::ParMarkRootClaimValue);
6820 } else {
6821 heap_region_iterate(&cl);
6822 }
6823 }
6824
6825 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6826 G1CollectedHeap* _g1h;
6827
6828 public:
6829 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6830 _g1h(g1h) {}
6831
6832 void do_code_blob(CodeBlob* cb) {
6833 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6834 if (nm == NULL) {
6835 return;
6836 }
6837
6838 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6839 _g1h->register_nmethod(nm);
6840 }
6841 }
6842 };
6843
6844 void G1CollectedHeap::rebuild_strong_code_roots() {
6845 RebuildStrongCodeRootClosure blob_cl(this);
6846 CodeCache::blobs_do(&blob_cl);
6847 }