1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess.
27 #endif
28
29 #include "precompiled.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "gc_implementation/g1/bufferingOopClosure.hpp"
33 #include "gc_implementation/g1/concurrentG1Refine.hpp"
34 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
35 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
36 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
37 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
38 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
39 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
40 #include "gc_implementation/g1/g1EvacFailure.hpp"
41 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
42 #include "gc_implementation/g1/g1Log.hpp"
43 #include "gc_implementation/g1/g1MarkSweep.hpp"
44 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
45 #include "gc_implementation/g1/g1RemSet.inline.hpp"
46 #include "gc_implementation/g1/g1StringDedup.hpp"
47 #include "gc_implementation/g1/g1YCTypes.hpp"
48 #include "gc_implementation/g1/heapRegion.inline.hpp"
49 #include "gc_implementation/g1/heapRegionRemSet.hpp"
50 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
51 #include "gc_implementation/g1/vm_operations_g1.hpp"
52 #include "gc_implementation/shared/gcHeapSummary.hpp"
53 #include "gc_implementation/shared/gcTimer.hpp"
54 #include "gc_implementation/shared/gcTrace.hpp"
55 #include "gc_implementation/shared/gcTraceTime.hpp"
56 #include "gc_implementation/shared/isGCActiveMark.hpp"
57 #include "memory/gcLocker.inline.hpp"
58 #include "memory/generationSpec.hpp"
59 #include "memory/iterator.hpp"
60 #include "memory/referenceProcessor.hpp"
61 #include "oops/oop.inline.hpp"
62 #include "oops/oop.pcgc.inline.hpp"
63 #include "runtime/prefetch.inline.hpp"
64 #include "runtime/orderAccess.inline.hpp"
65 #include "runtime/vmThread.hpp"
66 #include "utilities/ticks.hpp"
67
68 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
69
70 // turn it on so that the contents of the young list (scan-only /
71 // to-be-collected) are printed at "strategic" points before / during
72 // / after the collection --- this is useful for debugging
73 #define YOUNG_LIST_VERBOSE 0
74 // CURRENT STATUS
75 // This file is under construction. Search for "FIXME".
76
77 // INVARIANTS/NOTES
78 //
79 // All allocation activity covered by the G1CollectedHeap interface is
80 // serialized by acquiring the HeapLock. This happens in mem_allocate
81 // and allocate_new_tlab, which are the "entry" points to the
82 // allocation code from the rest of the JVM. (Note that this does not
83 // apply to TLAB allocation, which is not part of this interface: it
84 // is done by clients of this interface.)
85
86 // Notes on implementation of parallelism in different tasks.
87 //
88 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
89 // The number of GC workers is passed to heap_region_par_iterate_chunked().
90 // It does use run_task() which sets _n_workers in the task.
91 // G1ParTask executes g1_process_strong_roots() ->
92 // SharedHeap::process_strong_roots() which calls eventually to
93 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
94 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
95 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
96 //
97
98 // Local to this file.
99
100 class RefineCardTableEntryClosure: public CardTableEntryClosure {
101 G1RemSet* _g1rs;
102 ConcurrentG1Refine* _cg1r;
103 bool _concurrent;
104 public:
105 RefineCardTableEntryClosure(G1RemSet* g1rs,
106 ConcurrentG1Refine* cg1r) :
107 _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
108 {}
109 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
110 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
111 // This path is executed by the concurrent refine or mutator threads,
112 // concurrently, and so we do not care if card_ptr contains references
113 // that point into the collection set.
114 assert(!oops_into_cset, "should be");
115
116 if (_concurrent && SuspendibleThreadSet::should_yield()) {
117 // Caller will actually yield.
118 return false;
119 }
120 // Otherwise, we finished successfully; return true.
121 return true;
122 }
123 void set_concurrent(bool b) { _concurrent = b; }
124 };
125
126
127 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
128 int _calls;
129 G1CollectedHeap* _g1h;
130 CardTableModRefBS* _ctbs;
131 int _histo[256];
132 public:
133 ClearLoggedCardTableEntryClosure() :
134 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
135 {
136 for (int i = 0; i < 256; i++) _histo[i] = 0;
137 }
138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
139 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
140 _calls++;
141 unsigned char* ujb = (unsigned char*)card_ptr;
142 int ind = (int)(*ujb);
143 _histo[ind]++;
144 *card_ptr = -1;
145 }
146 return true;
147 }
148 int calls() { return _calls; }
149 void print_histo() {
150 gclog_or_tty->print_cr("Card table value histogram:");
151 for (int i = 0; i < 256; i++) {
152 if (_histo[i] != 0) {
153 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
154 }
155 }
156 }
157 };
158
159 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
160 int _calls;
161 G1CollectedHeap* _g1h;
162 CardTableModRefBS* _ctbs;
163 public:
164 RedirtyLoggedCardTableEntryClosure() :
165 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
166
167 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
168 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
169 _calls++;
170 *card_ptr = 0;
171 }
172 return true;
173 }
174 int calls() { return _calls; }
175 };
176
177 YoungList::YoungList(G1CollectedHeap* g1h) :
178 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
179 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
180 guarantee(check_list_empty(false), "just making sure...");
181 }
182
183 void YoungList::push_region(HeapRegion *hr) {
184 assert(!hr->is_young(), "should not already be young");
185 assert(hr->get_next_young_region() == NULL, "cause it should!");
186
187 hr->set_next_young_region(_head);
188 _head = hr;
189
190 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
191 ++_length;
192 }
193
194 void YoungList::add_survivor_region(HeapRegion* hr) {
195 assert(hr->is_survivor(), "should be flagged as survivor region");
196 assert(hr->get_next_young_region() == NULL, "cause it should!");
197
198 hr->set_next_young_region(_survivor_head);
199 if (_survivor_head == NULL) {
200 _survivor_tail = hr;
201 }
202 _survivor_head = hr;
203 ++_survivor_length;
204 }
205
206 void YoungList::empty_list(HeapRegion* list) {
207 while (list != NULL) {
208 HeapRegion* next = list->get_next_young_region();
209 list->set_next_young_region(NULL);
210 list->uninstall_surv_rate_group();
211 list->set_not_young();
212 list = next;
213 }
214 }
215
216 void YoungList::empty_list() {
217 assert(check_list_well_formed(), "young list should be well formed");
218
219 empty_list(_head);
220 _head = NULL;
221 _length = 0;
222
223 empty_list(_survivor_head);
224 _survivor_head = NULL;
225 _survivor_tail = NULL;
226 _survivor_length = 0;
227
228 _last_sampled_rs_lengths = 0;
229
230 assert(check_list_empty(false), "just making sure...");
231 }
232
233 bool YoungList::check_list_well_formed() {
234 bool ret = true;
235
236 uint length = 0;
237 HeapRegion* curr = _head;
238 HeapRegion* last = NULL;
239 while (curr != NULL) {
240 if (!curr->is_young()) {
241 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
242 "incorrectly tagged (y: %d, surv: %d)",
243 curr->bottom(), curr->end(),
244 curr->is_young(), curr->is_survivor());
245 ret = false;
246 }
247 ++length;
248 last = curr;
249 curr = curr->get_next_young_region();
250 }
251 ret = ret && (length == _length);
252
253 if (!ret) {
254 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
255 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
256 length, _length);
257 }
258
259 return ret;
260 }
261
262 bool YoungList::check_list_empty(bool check_sample) {
263 bool ret = true;
264
265 if (_length != 0) {
266 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
267 _length);
268 ret = false;
269 }
270 if (check_sample && _last_sampled_rs_lengths != 0) {
271 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
272 ret = false;
273 }
274 if (_head != NULL) {
275 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
276 ret = false;
277 }
278 if (!ret) {
279 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
280 }
281
282 return ret;
283 }
284
285 void
286 YoungList::rs_length_sampling_init() {
287 _sampled_rs_lengths = 0;
288 _curr = _head;
289 }
290
291 bool
292 YoungList::rs_length_sampling_more() {
293 return _curr != NULL;
294 }
295
296 void
297 YoungList::rs_length_sampling_next() {
298 assert( _curr != NULL, "invariant" );
299 size_t rs_length = _curr->rem_set()->occupied();
300
301 _sampled_rs_lengths += rs_length;
302
303 // The current region may not yet have been added to the
304 // incremental collection set (it gets added when it is
305 // retired as the current allocation region).
306 if (_curr->in_collection_set()) {
307 // Update the collection set policy information for this region
308 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
309 }
310
311 _curr = _curr->get_next_young_region();
312 if (_curr == NULL) {
313 _last_sampled_rs_lengths = _sampled_rs_lengths;
314 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
315 }
316 }
317
318 void
319 YoungList::reset_auxilary_lists() {
320 guarantee( is_empty(), "young list should be empty" );
321 assert(check_list_well_formed(), "young list should be well formed");
322
323 // Add survivor regions to SurvRateGroup.
324 _g1h->g1_policy()->note_start_adding_survivor_regions();
325 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
326
327 int young_index_in_cset = 0;
328 for (HeapRegion* curr = _survivor_head;
329 curr != NULL;
330 curr = curr->get_next_young_region()) {
331 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
332
333 // The region is a non-empty survivor so let's add it to
334 // the incremental collection set for the next evacuation
335 // pause.
336 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
337 young_index_in_cset += 1;
338 }
339 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
340 _g1h->g1_policy()->note_stop_adding_survivor_regions();
341
342 _head = _survivor_head;
343 _length = _survivor_length;
344 if (_survivor_head != NULL) {
345 assert(_survivor_tail != NULL, "cause it shouldn't be");
346 assert(_survivor_length > 0, "invariant");
347 _survivor_tail->set_next_young_region(NULL);
348 }
349
350 // Don't clear the survivor list handles until the start of
351 // the next evacuation pause - we need it in order to re-tag
352 // the survivor regions from this evacuation pause as 'young'
353 // at the start of the next.
354
355 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
356
357 assert(check_list_well_formed(), "young list should be well formed");
358 }
359
360 void YoungList::print() {
361 HeapRegion* lists[] = {_head, _survivor_head};
362 const char* names[] = {"YOUNG", "SURVIVOR"};
363
364 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
365 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
366 HeapRegion *curr = lists[list];
367 if (curr == NULL)
368 gclog_or_tty->print_cr(" empty");
369 while (curr != NULL) {
370 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
371 HR_FORMAT_PARAMS(curr),
372 curr->prev_top_at_mark_start(),
373 curr->next_top_at_mark_start(),
374 curr->age_in_surv_rate_group_cond());
375 curr = curr->get_next_young_region();
376 }
377 }
378
379 gclog_or_tty->cr();
380 }
381
382 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
383 {
384 // Claim the right to put the region on the dirty cards region list
385 // by installing a self pointer.
386 HeapRegion* next = hr->get_next_dirty_cards_region();
387 if (next == NULL) {
388 HeapRegion* res = (HeapRegion*)
389 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
390 NULL);
391 if (res == NULL) {
392 HeapRegion* head;
393 do {
394 // Put the region to the dirty cards region list.
395 head = _dirty_cards_region_list;
396 next = (HeapRegion*)
397 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
398 if (next == head) {
399 assert(hr->get_next_dirty_cards_region() == hr,
400 "hr->get_next_dirty_cards_region() != hr");
401 if (next == NULL) {
402 // The last region in the list points to itself.
403 hr->set_next_dirty_cards_region(hr);
404 } else {
405 hr->set_next_dirty_cards_region(next);
406 }
407 }
408 } while (next != head);
409 }
410 }
411 }
412
413 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
414 {
415 HeapRegion* head;
416 HeapRegion* hr;
417 do {
418 head = _dirty_cards_region_list;
419 if (head == NULL) {
420 return NULL;
421 }
422 HeapRegion* new_head = head->get_next_dirty_cards_region();
423 if (head == new_head) {
424 // The last region.
425 new_head = NULL;
426 }
427 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
428 head);
429 } while (hr != head);
430 assert(hr != NULL, "invariant");
431 hr->set_next_dirty_cards_region(NULL);
432 return hr;
433 }
434
435 #ifdef ASSERT
436 // A region is added to the collection set as it is retired
437 // so an address p can point to a region which will be in the
438 // collection set but has not yet been retired. This method
439 // therefore is only accurate during a GC pause after all
440 // regions have been retired. It is used for debugging
441 // to check if an nmethod has references to objects that can
442 // be move during a partial collection. Though it can be
443 // inaccurate, it is sufficient for G1 because the conservative
444 // implementation of is_scavengable() for G1 will indicate that
445 // all nmethods must be scanned during a partial collection.
446 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
447 HeapRegion* hr = heap_region_containing(p);
448 return hr != NULL && hr->in_collection_set();
449 }
450 #endif
451
452 // Returns true if the reference points to an object that
453 // can move in an incremental collection.
454 bool G1CollectedHeap::is_scavengable(const void* p) {
455 G1CollectedHeap* g1h = G1CollectedHeap::heap();
456 G1CollectorPolicy* g1p = g1h->g1_policy();
457 HeapRegion* hr = heap_region_containing(p);
458 if (hr == NULL) {
459 // null
460 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
461 return false;
462 } else {
463 return !hr->isHumongous();
464 }
465 }
466
467 void G1CollectedHeap::check_ct_logs_at_safepoint() {
468 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
469 CardTableModRefBS* ct_bs = g1_barrier_set();
470
471 // Count the dirty cards at the start.
472 CountNonCleanMemRegionClosure count1(this);
473 ct_bs->mod_card_iterate(&count1);
474 int orig_count = count1.n();
475
476 // First clear the logged cards.
477 ClearLoggedCardTableEntryClosure clear;
478 dcqs.set_closure(&clear);
479 dcqs.apply_closure_to_all_completed_buffers();
480 dcqs.iterate_closure_all_threads(false);
481 clear.print_histo();
482
483 // Now ensure that there's no dirty cards.
484 CountNonCleanMemRegionClosure count2(this);
485 ct_bs->mod_card_iterate(&count2);
486 if (count2.n() != 0) {
487 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
488 count2.n(), orig_count);
489 }
490 guarantee(count2.n() == 0, "Card table should be clean.");
491
492 RedirtyLoggedCardTableEntryClosure redirty;
493 JavaThread::dirty_card_queue_set().set_closure(&redirty);
494 dcqs.apply_closure_to_all_completed_buffers();
495 dcqs.iterate_closure_all_threads(false);
496 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
497 clear.calls(), orig_count);
498 guarantee(redirty.calls() == clear.calls(),
499 "Or else mechanism is broken.");
500
501 CountNonCleanMemRegionClosure count3(this);
502 ct_bs->mod_card_iterate(&count3);
503 if (count3.n() != orig_count) {
504 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
505 orig_count, count3.n());
506 guarantee(count3.n() >= orig_count, "Should have restored them all.");
507 }
508
509 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
510 }
511
512 // Private class members.
513
514 G1CollectedHeap* G1CollectedHeap::_g1h;
515
516 // Private methods.
517
518 HeapRegion*
519 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
520 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
521 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
522 if (!_secondary_free_list.is_empty()) {
523 if (G1ConcRegionFreeingVerbose) {
524 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
525 "secondary_free_list has %u entries",
526 _secondary_free_list.length());
527 }
528 // It looks as if there are free regions available on the
529 // secondary_free_list. Let's move them to the free_list and try
530 // again to allocate from it.
531 append_secondary_free_list();
532
533 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
534 "empty we should have moved at least one entry to the free_list");
535 HeapRegion* res = _free_list.remove_region(is_old);
536 if (G1ConcRegionFreeingVerbose) {
537 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
538 "allocated "HR_FORMAT" from secondary_free_list",
539 HR_FORMAT_PARAMS(res));
540 }
541 return res;
542 }
543
544 // Wait here until we get notified either when (a) there are no
545 // more free regions coming or (b) some regions have been moved on
546 // the secondary_free_list.
547 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
548 }
549
550 if (G1ConcRegionFreeingVerbose) {
551 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
552 "could not allocate from secondary_free_list");
553 }
554 return NULL;
555 }
556
557 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
558 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
559 "the only time we use this to allocate a humongous region is "
560 "when we are allocating a single humongous region");
561
562 HeapRegion* res;
563 if (G1StressConcRegionFreeing) {
564 if (!_secondary_free_list.is_empty()) {
565 if (G1ConcRegionFreeingVerbose) {
566 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
567 "forced to look at the secondary_free_list");
568 }
569 res = new_region_try_secondary_free_list(is_old);
570 if (res != NULL) {
571 return res;
572 }
573 }
574 }
575
576 res = _free_list.remove_region(is_old);
577
578 if (res == NULL) {
579 if (G1ConcRegionFreeingVerbose) {
580 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
581 "res == NULL, trying the secondary_free_list");
582 }
583 res = new_region_try_secondary_free_list(is_old);
584 }
585 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
586 // Currently, only attempts to allocate GC alloc regions set
587 // do_expand to true. So, we should only reach here during a
588 // safepoint. If this assumption changes we might have to
589 // reconsider the use of _expand_heap_after_alloc_failure.
590 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
591
592 ergo_verbose1(ErgoHeapSizing,
593 "attempt heap expansion",
594 ergo_format_reason("region allocation request failed")
595 ergo_format_byte("allocation request"),
596 word_size * HeapWordSize);
597 if (expand(word_size * HeapWordSize)) {
598 // Given that expand() succeeded in expanding the heap, and we
599 // always expand the heap by an amount aligned to the heap
600 // region size, the free list should in theory not be empty.
601 // In either case remove_region() will check for NULL.
602 res = _free_list.remove_region(is_old);
603 } else {
604 _expand_heap_after_alloc_failure = false;
605 }
606 }
607 return res;
608 }
609
610 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
611 size_t word_size) {
612 assert(isHumongous(word_size), "word_size should be humongous");
613 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
614
615 uint first = G1_NULL_HRS_INDEX;
616 if (num_regions == 1) {
617 // Only one region to allocate, no need to go through the slower
618 // path. The caller will attempt the expansion if this fails, so
619 // let's not try to expand here too.
620 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
621 if (hr != NULL) {
622 first = hr->hrs_index();
623 } else {
624 first = G1_NULL_HRS_INDEX;
625 }
626 } else {
627 // We can't allocate humongous regions while cleanupComplete() is
628 // running, since some of the regions we find to be empty might not
629 // yet be added to the free list and it is not straightforward to
630 // know which list they are on so that we can remove them. Note
631 // that we only need to do this if we need to allocate more than
632 // one region to satisfy the current humongous allocation
633 // request. If we are only allocating one region we use the common
634 // region allocation code (see above).
635 wait_while_free_regions_coming();
636 append_secondary_free_list_if_not_empty_with_lock();
637
638 if (free_regions() >= num_regions) {
639 first = _hrs.find_contiguous(num_regions);
640 if (first != G1_NULL_HRS_INDEX) {
641 for (uint i = first; i < first + num_regions; ++i) {
642 HeapRegion* hr = region_at(i);
643 assert(hr->is_empty(), "sanity");
644 assert(is_on_master_free_list(hr), "sanity");
645 hr->set_pending_removal(true);
646 }
647 _free_list.remove_all_pending(num_regions);
648 }
649 }
650 }
651 return first;
652 }
653
654 HeapWord*
655 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
656 uint num_regions,
657 size_t word_size) {
658 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
659 assert(isHumongous(word_size), "word_size should be humongous");
660 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
661
662 // Index of last region in the series + 1.
663 uint last = first + num_regions;
664
665 // We need to initialize the region(s) we just discovered. This is
666 // a bit tricky given that it can happen concurrently with
667 // refinement threads refining cards on these regions and
668 // potentially wanting to refine the BOT as they are scanning
669 // those cards (this can happen shortly after a cleanup; see CR
670 // 6991377). So we have to set up the region(s) carefully and in
671 // a specific order.
672
673 // The word size sum of all the regions we will allocate.
674 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
675 assert(word_size <= word_size_sum, "sanity");
676
677 // This will be the "starts humongous" region.
678 HeapRegion* first_hr = region_at(first);
679 // The header of the new object will be placed at the bottom of
680 // the first region.
681 HeapWord* new_obj = first_hr->bottom();
682 // This will be the new end of the first region in the series that
683 // should also match the end of the last region in the series.
684 HeapWord* new_end = new_obj + word_size_sum;
685 // This will be the new top of the first region that will reflect
686 // this allocation.
687 HeapWord* new_top = new_obj + word_size;
688
689 // First, we need to zero the header of the space that we will be
690 // allocating. When we update top further down, some refinement
691 // threads might try to scan the region. By zeroing the header we
692 // ensure that any thread that will try to scan the region will
693 // come across the zero klass word and bail out.
694 //
695 // NOTE: It would not have been correct to have used
696 // CollectedHeap::fill_with_object() and make the space look like
697 // an int array. The thread that is doing the allocation will
698 // later update the object header to a potentially different array
699 // type and, for a very short period of time, the klass and length
700 // fields will be inconsistent. This could cause a refinement
701 // thread to calculate the object size incorrectly.
702 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
703
704 // We will set up the first region as "starts humongous". This
705 // will also update the BOT covering all the regions to reflect
706 // that there is a single object that starts at the bottom of the
707 // first region.
708 first_hr->set_startsHumongous(new_top, new_end);
709
710 // Then, if there are any, we will set up the "continues
711 // humongous" regions.
712 HeapRegion* hr = NULL;
713 for (uint i = first + 1; i < last; ++i) {
714 hr = region_at(i);
715 hr->set_continuesHumongous(first_hr);
716 }
717 // If we have "continues humongous" regions (hr != NULL), then the
718 // end of the last one should match new_end.
719 assert(hr == NULL || hr->end() == new_end, "sanity");
720
721 // Up to this point no concurrent thread would have been able to
722 // do any scanning on any region in this series. All the top
723 // fields still point to bottom, so the intersection between
724 // [bottom,top] and [card_start,card_end] will be empty. Before we
725 // update the top fields, we'll do a storestore to make sure that
726 // no thread sees the update to top before the zeroing of the
727 // object header and the BOT initialization.
728 OrderAccess::storestore();
729
730 // Now that the BOT and the object header have been initialized,
731 // we can update top of the "starts humongous" region.
732 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
733 "new_top should be in this region");
734 first_hr->set_top(new_top);
735 if (_hr_printer.is_active()) {
736 HeapWord* bottom = first_hr->bottom();
737 HeapWord* end = first_hr->orig_end();
738 if ((first + 1) == last) {
739 // the series has a single humongous region
740 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
741 } else {
742 // the series has more than one humongous regions
743 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
744 }
745 }
746
747 // Now, we will update the top fields of the "continues humongous"
748 // regions. The reason we need to do this is that, otherwise,
749 // these regions would look empty and this will confuse parts of
750 // G1. For example, the code that looks for a consecutive number
751 // of empty regions will consider them empty and try to
752 // re-allocate them. We can extend is_empty() to also include
753 // !continuesHumongous(), but it is easier to just update the top
754 // fields here. The way we set top for all regions (i.e., top ==
755 // end for all regions but the last one, top == new_top for the
756 // last one) is actually used when we will free up the humongous
757 // region in free_humongous_region().
758 hr = NULL;
759 for (uint i = first + 1; i < last; ++i) {
760 hr = region_at(i);
761 if ((i + 1) == last) {
762 // last continues humongous region
763 assert(hr->bottom() < new_top && new_top <= hr->end(),
764 "new_top should fall on this region");
765 hr->set_top(new_top);
766 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
767 } else {
768 // not last one
769 assert(new_top > hr->end(), "new_top should be above this region");
770 hr->set_top(hr->end());
771 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
772 }
773 }
774 // If we have continues humongous regions (hr != NULL), then the
775 // end of the last one should match new_end and its top should
776 // match new_top.
777 assert(hr == NULL ||
778 (hr->end() == new_end && hr->top() == new_top), "sanity");
779
780 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
781 _summary_bytes_used += first_hr->used();
782 _humongous_set.add(first_hr);
783
784 return new_obj;
785 }
786
787 // If could fit into free regions w/o expansion, try.
788 // Otherwise, if can expand, do so.
789 // Otherwise, if using ex regions might help, try with ex given back.
790 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
791 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
792
793 verify_region_sets_optional();
794
795 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
796 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
797 uint x_num = expansion_regions();
798 uint fs = _hrs.free_suffix();
799 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
800 if (first == G1_NULL_HRS_INDEX) {
801 // The only thing we can do now is attempt expansion.
802 if (fs + x_num >= num_regions) {
803 // If the number of regions we're trying to allocate for this
804 // object is at most the number of regions in the free suffix,
805 // then the call to humongous_obj_allocate_find_first() above
806 // should have succeeded and we wouldn't be here.
807 //
808 // We should only be trying to expand when the free suffix is
809 // not sufficient for the object _and_ we have some expansion
810 // room available.
811 assert(num_regions > fs, "earlier allocation should have succeeded");
812
813 ergo_verbose1(ErgoHeapSizing,
814 "attempt heap expansion",
815 ergo_format_reason("humongous allocation request failed")
816 ergo_format_byte("allocation request"),
817 word_size * HeapWordSize);
818 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
819 // Even though the heap was expanded, it might not have
820 // reached the desired size. So, we cannot assume that the
821 // allocation will succeed.
822 first = humongous_obj_allocate_find_first(num_regions, word_size);
823 }
824 }
825 }
826
827 HeapWord* result = NULL;
828 if (first != G1_NULL_HRS_INDEX) {
829 result =
830 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
831 assert(result != NULL, "it should always return a valid result");
832
833 // A successful humongous object allocation changes the used space
834 // information of the old generation so we need to recalculate the
835 // sizes and update the jstat counters here.
836 g1mm()->update_sizes();
837 }
838
839 verify_region_sets_optional();
840
841 return result;
842 }
843
844 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
845 assert_heap_not_locked_and_not_at_safepoint();
846 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
847
848 unsigned int dummy_gc_count_before;
849 int dummy_gclocker_retry_count = 0;
850 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
851 }
852
853 HeapWord*
854 G1CollectedHeap::mem_allocate(size_t word_size,
855 bool* gc_overhead_limit_was_exceeded) {
856 assert_heap_not_locked_and_not_at_safepoint();
857
858 // Loop until the allocation is satisfied, or unsatisfied after GC.
859 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
860 unsigned int gc_count_before;
861
862 HeapWord* result = NULL;
863 if (!isHumongous(word_size)) {
864 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
865 } else {
866 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
867 }
868 if (result != NULL) {
869 return result;
870 }
871
872 // Create the garbage collection operation...
873 VM_G1CollectForAllocation op(gc_count_before, word_size);
874 // ...and get the VM thread to execute it.
875 VMThread::execute(&op);
876
877 if (op.prologue_succeeded() && op.pause_succeeded()) {
878 // If the operation was successful we'll return the result even
879 // if it is NULL. If the allocation attempt failed immediately
880 // after a Full GC, it's unlikely we'll be able to allocate now.
881 HeapWord* result = op.result();
882 if (result != NULL && !isHumongous(word_size)) {
883 // Allocations that take place on VM operations do not do any
884 // card dirtying and we have to do it here. We only have to do
885 // this for non-humongous allocations, though.
886 dirty_young_block(result, word_size);
887 }
888 return result;
889 } else {
890 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
891 return NULL;
892 }
893 assert(op.result() == NULL,
894 "the result should be NULL if the VM op did not succeed");
895 }
896
897 // Give a warning if we seem to be looping forever.
898 if ((QueuedAllocationWarningCount > 0) &&
899 (try_count % QueuedAllocationWarningCount == 0)) {
900 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
901 }
902 }
903
904 ShouldNotReachHere();
905 return NULL;
906 }
907
908 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
909 unsigned int *gc_count_before_ret,
910 int* gclocker_retry_count_ret) {
911 // Make sure you read the note in attempt_allocation_humongous().
912
913 assert_heap_not_locked_and_not_at_safepoint();
914 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
915 "be called for humongous allocation requests");
916
917 // We should only get here after the first-level allocation attempt
918 // (attempt_allocation()) failed to allocate.
919
920 // We will loop until a) we manage to successfully perform the
921 // allocation or b) we successfully schedule a collection which
922 // fails to perform the allocation. b) is the only case when we'll
923 // return NULL.
924 HeapWord* result = NULL;
925 for (int try_count = 1; /* we'll return */; try_count += 1) {
926 bool should_try_gc;
927 unsigned int gc_count_before;
928
929 {
930 MutexLockerEx x(Heap_lock);
931
932 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
933 false /* bot_updates */);
934 if (result != NULL) {
935 return result;
936 }
937
938 // If we reach here, attempt_allocation_locked() above failed to
939 // allocate a new region. So the mutator alloc region should be NULL.
940 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
941
942 if (GC_locker::is_active_and_needs_gc()) {
943 if (g1_policy()->can_expand_young_list()) {
944 // No need for an ergo verbose message here,
945 // can_expand_young_list() does this when it returns true.
946 result = _mutator_alloc_region.attempt_allocation_force(word_size,
947 false /* bot_updates */);
948 if (result != NULL) {
949 return result;
950 }
951 }
952 should_try_gc = false;
953 } else {
954 // The GCLocker may not be active but the GCLocker initiated
955 // GC may not yet have been performed (GCLocker::needs_gc()
956 // returns true). In this case we do not try this GC and
957 // wait until the GCLocker initiated GC is performed, and
958 // then retry the allocation.
959 if (GC_locker::needs_gc()) {
960 should_try_gc = false;
961 } else {
962 // Read the GC count while still holding the Heap_lock.
963 gc_count_before = total_collections();
964 should_try_gc = true;
965 }
966 }
967 }
968
969 if (should_try_gc) {
970 bool succeeded;
971 result = do_collection_pause(word_size, gc_count_before, &succeeded,
972 GCCause::_g1_inc_collection_pause);
973 if (result != NULL) {
974 assert(succeeded, "only way to get back a non-NULL result");
975 return result;
976 }
977
978 if (succeeded) {
979 // If we get here we successfully scheduled a collection which
980 // failed to allocate. No point in trying to allocate
981 // further. We'll just return NULL.
982 MutexLockerEx x(Heap_lock);
983 *gc_count_before_ret = total_collections();
984 return NULL;
985 }
986 } else {
987 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
988 MutexLockerEx x(Heap_lock);
989 *gc_count_before_ret = total_collections();
990 return NULL;
991 }
992 // The GCLocker is either active or the GCLocker initiated
993 // GC has not yet been performed. Stall until it is and
994 // then retry the allocation.
995 GC_locker::stall_until_clear();
996 (*gclocker_retry_count_ret) += 1;
997 }
998
999 // We can reach here if we were unsuccessful in scheduling a
1000 // collection (because another thread beat us to it) or if we were
1001 // stalled due to the GC locker. In either can we should retry the
1002 // allocation attempt in case another thread successfully
1003 // performed a collection and reclaimed enough space. We do the
1004 // first attempt (without holding the Heap_lock) here and the
1005 // follow-on attempt will be at the start of the next loop
1006 // iteration (after taking the Heap_lock).
1007 result = _mutator_alloc_region.attempt_allocation(word_size,
1008 false /* bot_updates */);
1009 if (result != NULL) {
1010 return result;
1011 }
1012
1013 // Give a warning if we seem to be looping forever.
1014 if ((QueuedAllocationWarningCount > 0) &&
1015 (try_count % QueuedAllocationWarningCount == 0)) {
1016 warning("G1CollectedHeap::attempt_allocation_slow() "
1017 "retries %d times", try_count);
1018 }
1019 }
1020
1021 ShouldNotReachHere();
1022 return NULL;
1023 }
1024
1025 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1026 unsigned int * gc_count_before_ret,
1027 int* gclocker_retry_count_ret) {
1028 // The structure of this method has a lot of similarities to
1029 // attempt_allocation_slow(). The reason these two were not merged
1030 // into a single one is that such a method would require several "if
1031 // allocation is not humongous do this, otherwise do that"
1032 // conditional paths which would obscure its flow. In fact, an early
1033 // version of this code did use a unified method which was harder to
1034 // follow and, as a result, it had subtle bugs that were hard to
1035 // track down. So keeping these two methods separate allows each to
1036 // be more readable. It will be good to keep these two in sync as
1037 // much as possible.
1038
1039 assert_heap_not_locked_and_not_at_safepoint();
1040 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1041 "should only be called for humongous allocations");
1042
1043 // Humongous objects can exhaust the heap quickly, so we should check if we
1044 // need to start a marking cycle at each humongous object allocation. We do
1045 // the check before we do the actual allocation. The reason for doing it
1046 // before the allocation is that we avoid having to keep track of the newly
1047 // allocated memory while we do a GC.
1048 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1049 word_size)) {
1050 collect(GCCause::_g1_humongous_allocation);
1051 }
1052
1053 // We will loop until a) we manage to successfully perform the
1054 // allocation or b) we successfully schedule a collection which
1055 // fails to perform the allocation. b) is the only case when we'll
1056 // return NULL.
1057 HeapWord* result = NULL;
1058 for (int try_count = 1; /* we'll return */; try_count += 1) {
1059 bool should_try_gc;
1060 unsigned int gc_count_before;
1061
1062 {
1063 MutexLockerEx x(Heap_lock);
1064
1065 // Given that humongous objects are not allocated in young
1066 // regions, we'll first try to do the allocation without doing a
1067 // collection hoping that there's enough space in the heap.
1068 result = humongous_obj_allocate(word_size);
1069 if (result != NULL) {
1070 return result;
1071 }
1072
1073 if (GC_locker::is_active_and_needs_gc()) {
1074 should_try_gc = false;
1075 } else {
1076 // The GCLocker may not be active but the GCLocker initiated
1077 // GC may not yet have been performed (GCLocker::needs_gc()
1078 // returns true). In this case we do not try this GC and
1079 // wait until the GCLocker initiated GC is performed, and
1080 // then retry the allocation.
1081 if (GC_locker::needs_gc()) {
1082 should_try_gc = false;
1083 } else {
1084 // Read the GC count while still holding the Heap_lock.
1085 gc_count_before = total_collections();
1086 should_try_gc = true;
1087 }
1088 }
1089 }
1090
1091 if (should_try_gc) {
1092 // If we failed to allocate the humongous object, we should try to
1093 // do a collection pause (if we're allowed) in case it reclaims
1094 // enough space for the allocation to succeed after the pause.
1095
1096 bool succeeded;
1097 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1098 GCCause::_g1_humongous_allocation);
1099 if (result != NULL) {
1100 assert(succeeded, "only way to get back a non-NULL result");
1101 return result;
1102 }
1103
1104 if (succeeded) {
1105 // If we get here we successfully scheduled a collection which
1106 // failed to allocate. No point in trying to allocate
1107 // further. We'll just return NULL.
1108 MutexLockerEx x(Heap_lock);
1109 *gc_count_before_ret = total_collections();
1110 return NULL;
1111 }
1112 } else {
1113 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1114 MutexLockerEx x(Heap_lock);
1115 *gc_count_before_ret = total_collections();
1116 return NULL;
1117 }
1118 // The GCLocker is either active or the GCLocker initiated
1119 // GC has not yet been performed. Stall until it is and
1120 // then retry the allocation.
1121 GC_locker::stall_until_clear();
1122 (*gclocker_retry_count_ret) += 1;
1123 }
1124
1125 // We can reach here if we were unsuccessful in scheduling a
1126 // collection (because another thread beat us to it) or if we were
1127 // stalled due to the GC locker. In either can we should retry the
1128 // allocation attempt in case another thread successfully
1129 // performed a collection and reclaimed enough space. Give a
1130 // warning if we seem to be looping forever.
1131
1132 if ((QueuedAllocationWarningCount > 0) &&
1133 (try_count % QueuedAllocationWarningCount == 0)) {
1134 warning("G1CollectedHeap::attempt_allocation_humongous() "
1135 "retries %d times", try_count);
1136 }
1137 }
1138
1139 ShouldNotReachHere();
1140 return NULL;
1141 }
1142
1143 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1144 bool expect_null_mutator_alloc_region) {
1145 assert_at_safepoint(true /* should_be_vm_thread */);
1146 assert(_mutator_alloc_region.get() == NULL ||
1147 !expect_null_mutator_alloc_region,
1148 "the current alloc region was unexpectedly found to be non-NULL");
1149
1150 if (!isHumongous(word_size)) {
1151 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1152 false /* bot_updates */);
1153 } else {
1154 HeapWord* result = humongous_obj_allocate(word_size);
1155 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1156 g1_policy()->set_initiate_conc_mark_if_possible();
1157 }
1158 return result;
1159 }
1160
1161 ShouldNotReachHere();
1162 }
1163
1164 class PostMCRemSetClearClosure: public HeapRegionClosure {
1165 G1CollectedHeap* _g1h;
1166 ModRefBarrierSet* _mr_bs;
1167 public:
1168 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1169 _g1h(g1h), _mr_bs(mr_bs) {}
1170
1171 bool doHeapRegion(HeapRegion* r) {
1172 HeapRegionRemSet* hrrs = r->rem_set();
1173
1174 if (r->continuesHumongous()) {
1175 // We'll assert that the strong code root list and RSet is empty
1176 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1177 assert(hrrs->occupied() == 0, "RSet should be empty");
1178 return false;
1179 }
1180
1181 _g1h->reset_gc_time_stamps(r);
1182 hrrs->clear();
1183 // You might think here that we could clear just the cards
1184 // corresponding to the used region. But no: if we leave a dirty card
1185 // in a region we might allocate into, then it would prevent that card
1186 // from being enqueued, and cause it to be missed.
1187 // Re: the performance cost: we shouldn't be doing full GC anyway!
1188 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1189
1190 return false;
1191 }
1192 };
1193
1194 void G1CollectedHeap::clear_rsets_post_compaction() {
1195 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1196 heap_region_iterate(&rs_clear);
1197 }
1198
1199 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1200 G1CollectedHeap* _g1h;
1201 UpdateRSOopClosure _cl;
1202 int _worker_i;
1203 public:
1204 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1205 _cl(g1->g1_rem_set(), worker_i),
1206 _worker_i(worker_i),
1207 _g1h(g1)
1208 { }
1209
1210 bool doHeapRegion(HeapRegion* r) {
1211 if (!r->continuesHumongous()) {
1212 _cl.set_from(r);
1213 r->oop_iterate(&_cl);
1214 }
1215 return false;
1216 }
1217 };
1218
1219 class ParRebuildRSTask: public AbstractGangTask {
1220 G1CollectedHeap* _g1;
1221 public:
1222 ParRebuildRSTask(G1CollectedHeap* g1)
1223 : AbstractGangTask("ParRebuildRSTask"),
1224 _g1(g1)
1225 { }
1226
1227 void work(uint worker_id) {
1228 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1229 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1230 _g1->workers()->active_workers(),
1231 HeapRegion::RebuildRSClaimValue);
1232 }
1233 };
1234
1235 class PostCompactionPrinterClosure: public HeapRegionClosure {
1236 private:
1237 G1HRPrinter* _hr_printer;
1238 public:
1239 bool doHeapRegion(HeapRegion* hr) {
1240 assert(!hr->is_young(), "not expecting to find young regions");
1241 // We only generate output for non-empty regions.
1242 if (!hr->is_empty()) {
1243 if (!hr->isHumongous()) {
1244 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1245 } else if (hr->startsHumongous()) {
1246 if (hr->region_num() == 1) {
1247 // single humongous region
1248 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1249 } else {
1250 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1251 }
1252 } else {
1253 assert(hr->continuesHumongous(), "only way to get here");
1254 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1255 }
1256 }
1257 return false;
1258 }
1259
1260 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1261 : _hr_printer(hr_printer) { }
1262 };
1263
1264 void G1CollectedHeap::print_hrs_post_compaction() {
1265 PostCompactionPrinterClosure cl(hr_printer());
1266 heap_region_iterate(&cl);
1267 }
1268
1269 bool G1CollectedHeap::do_collection(bool explicit_gc,
1270 bool clear_all_soft_refs,
1271 size_t word_size) {
1272 assert_at_safepoint(true /* should_be_vm_thread */);
1273
1274 if (GC_locker::check_active_before_gc()) {
1275 return false;
1276 }
1277
1278 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1279 gc_timer->register_gc_start();
1280
1281 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1282 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1283
1284 SvcGCMarker sgcm(SvcGCMarker::FULL);
1285 ResourceMark rm;
1286
1287 print_heap_before_gc();
1288 trace_heap_before_gc(gc_tracer);
1289
1290 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1291
1292 verify_region_sets_optional();
1293
1294 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1295 collector_policy()->should_clear_all_soft_refs();
1296
1297 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1298
1299 {
1300 IsGCActiveMark x;
1301
1302 // Timing
1303 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1304 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1305 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1306
1307 {
1308 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1309 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1310 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1311
1312 double start = os::elapsedTime();
1313 g1_policy()->record_full_collection_start();
1314
1315 // Note: When we have a more flexible GC logging framework that
1316 // allows us to add optional attributes to a GC log record we
1317 // could consider timing and reporting how long we wait in the
1318 // following two methods.
1319 wait_while_free_regions_coming();
1320 // If we start the compaction before the CM threads finish
1321 // scanning the root regions we might trip them over as we'll
1322 // be moving objects / updating references. So let's wait until
1323 // they are done. By telling them to abort, they should complete
1324 // early.
1325 _cm->root_regions()->abort();
1326 _cm->root_regions()->wait_until_scan_finished();
1327 append_secondary_free_list_if_not_empty_with_lock();
1328
1329 gc_prologue(true);
1330 increment_total_collections(true /* full gc */);
1331 increment_old_marking_cycles_started();
1332
1333 assert(used() == recalculate_used(), "Should be equal");
1334
1335 verify_before_gc();
1336
1337 pre_full_gc_dump(gc_timer);
1338
1339 COMPILER2_PRESENT(DerivedPointerTable::clear());
1340
1341 // Disable discovery and empty the discovered lists
1342 // for the CM ref processor.
1343 ref_processor_cm()->disable_discovery();
1344 ref_processor_cm()->abandon_partial_discovery();
1345 ref_processor_cm()->verify_no_references_recorded();
1346
1347 // Abandon current iterations of concurrent marking and concurrent
1348 // refinement, if any are in progress. We have to do this before
1349 // wait_until_scan_finished() below.
1350 concurrent_mark()->abort();
1351
1352 // Make sure we'll choose a new allocation region afterwards.
1353 release_mutator_alloc_region();
1354 abandon_gc_alloc_regions();
1355 g1_rem_set()->cleanupHRRS();
1356
1357 // We should call this after we retire any currently active alloc
1358 // regions so that all the ALLOC / RETIRE events are generated
1359 // before the start GC event.
1360 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1361
1362 // We may have added regions to the current incremental collection
1363 // set between the last GC or pause and now. We need to clear the
1364 // incremental collection set and then start rebuilding it afresh
1365 // after this full GC.
1366 abandon_collection_set(g1_policy()->inc_cset_head());
1367 g1_policy()->clear_incremental_cset();
1368 g1_policy()->stop_incremental_cset_building();
1369
1370 tear_down_region_sets(false /* free_list_only */);
1371 g1_policy()->set_gcs_are_young(true);
1372
1373 // See the comments in g1CollectedHeap.hpp and
1374 // G1CollectedHeap::ref_processing_init() about
1375 // how reference processing currently works in G1.
1376
1377 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1378 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1379
1380 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1381 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1382
1383 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1384 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1385
1386 // Do collection work
1387 {
1388 HandleMark hm; // Discard invalid handles created during gc
1389 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1390 }
1391
1392 assert(free_regions() == 0, "we should not have added any free regions");
1393 rebuild_region_sets(false /* free_list_only */);
1394
1395 // Enqueue any discovered reference objects that have
1396 // not been removed from the discovered lists.
1397 ref_processor_stw()->enqueue_discovered_references();
1398
1399 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1400
1401 MemoryService::track_memory_usage();
1402
1403 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1404 ref_processor_stw()->verify_no_references_recorded();
1405
1406 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1407 ClassLoaderDataGraph::purge();
1408 MetaspaceAux::verify_metrics();
1409
1410 // Note: since we've just done a full GC, concurrent
1411 // marking is no longer active. Therefore we need not
1412 // re-enable reference discovery for the CM ref processor.
1413 // That will be done at the start of the next marking cycle.
1414 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1415 ref_processor_cm()->verify_no_references_recorded();
1416
1417 reset_gc_time_stamp();
1418 // Since everything potentially moved, we will clear all remembered
1419 // sets, and clear all cards. Later we will rebuild remembered
1420 // sets. We will also reset the GC time stamps of the regions.
1421 clear_rsets_post_compaction();
1422 check_gc_time_stamps();
1423
1424 // Resize the heap if necessary.
1425 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1426
1427 if (_hr_printer.is_active()) {
1428 // We should do this after we potentially resize the heap so
1429 // that all the COMMIT / UNCOMMIT events are generated before
1430 // the end GC event.
1431
1432 print_hrs_post_compaction();
1433 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1434 }
1435
1436 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1437 if (hot_card_cache->use_cache()) {
1438 hot_card_cache->reset_card_counts();
1439 hot_card_cache->reset_hot_cache();
1440 }
1441
1442 // Rebuild remembered sets of all regions.
1443 if (G1CollectedHeap::use_parallel_gc_threads()) {
1444 uint n_workers =
1445 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1446 workers()->active_workers(),
1447 Threads::number_of_non_daemon_threads());
1448 assert(UseDynamicNumberOfGCThreads ||
1449 n_workers == workers()->total_workers(),
1450 "If not dynamic should be using all the workers");
1451 workers()->set_active_workers(n_workers);
1452 // Set parallel threads in the heap (_n_par_threads) only
1453 // before a parallel phase and always reset it to 0 after
1454 // the phase so that the number of parallel threads does
1455 // no get carried forward to a serial phase where there
1456 // may be code that is "possibly_parallel".
1457 set_par_threads(n_workers);
1458
1459 ParRebuildRSTask rebuild_rs_task(this);
1460 assert(check_heap_region_claim_values(
1461 HeapRegion::InitialClaimValue), "sanity check");
1462 assert(UseDynamicNumberOfGCThreads ||
1463 workers()->active_workers() == workers()->total_workers(),
1464 "Unless dynamic should use total workers");
1465 // Use the most recent number of active workers
1466 assert(workers()->active_workers() > 0,
1467 "Active workers not properly set");
1468 set_par_threads(workers()->active_workers());
1469 workers()->run_task(&rebuild_rs_task);
1470 set_par_threads(0);
1471 assert(check_heap_region_claim_values(
1472 HeapRegion::RebuildRSClaimValue), "sanity check");
1473 reset_heap_region_claim_values();
1474 } else {
1475 RebuildRSOutOfRegionClosure rebuild_rs(this);
1476 heap_region_iterate(&rebuild_rs);
1477 }
1478
1479 // Rebuild the strong code root lists for each region
1480 rebuild_strong_code_roots();
1481
1482 if (true) { // FIXME
1483 MetaspaceGC::compute_new_size();
1484 }
1485
1486 #ifdef TRACESPINNING
1487 ParallelTaskTerminator::print_termination_counts();
1488 #endif
1489
1490 // Discard all rset updates
1491 JavaThread::dirty_card_queue_set().abandon_logs();
1492 assert(!G1DeferredRSUpdate
1493 || (G1DeferredRSUpdate &&
1494 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1495
1496 _young_list->reset_sampled_info();
1497 // At this point there should be no regions in the
1498 // entire heap tagged as young.
1499 assert(check_young_list_empty(true /* check_heap */),
1500 "young list should be empty at this point");
1501
1502 // Update the number of full collections that have been completed.
1503 increment_old_marking_cycles_completed(false /* concurrent */);
1504
1505 _hrs.verify_optional();
1506 verify_region_sets_optional();
1507
1508 verify_after_gc();
1509
1510 // Start a new incremental collection set for the next pause
1511 assert(g1_policy()->collection_set() == NULL, "must be");
1512 g1_policy()->start_incremental_cset_building();
1513
1514 clear_cset_fast_test();
1515
1516 init_mutator_alloc_region();
1517
1518 double end = os::elapsedTime();
1519 g1_policy()->record_full_collection_end();
1520
1521 if (G1Log::fine()) {
1522 g1_policy()->print_heap_transition();
1523 }
1524
1525 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1526 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1527 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1528 // before any GC notifications are raised.
1529 g1mm()->update_sizes();
1530
1531 gc_epilogue(true);
1532 }
1533
1534 if (G1Log::finer()) {
1535 g1_policy()->print_detailed_heap_transition(true /* full */);
1536 }
1537
1538 print_heap_after_gc();
1539 trace_heap_after_gc(gc_tracer);
1540
1541 post_full_gc_dump(gc_timer);
1542
1543 gc_timer->register_gc_end();
1544 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1545 }
1546
1547 return true;
1548 }
1549
1550 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1551 // do_collection() will return whether it succeeded in performing
1552 // the GC. Currently, there is no facility on the
1553 // do_full_collection() API to notify the caller than the collection
1554 // did not succeed (e.g., because it was locked out by the GC
1555 // locker). So, right now, we'll ignore the return value.
1556 bool dummy = do_collection(true, /* explicit_gc */
1557 clear_all_soft_refs,
1558 0 /* word_size */);
1559 }
1560
1561 // This code is mostly copied from TenuredGeneration.
1562 void
1563 G1CollectedHeap::
1564 resize_if_necessary_after_full_collection(size_t word_size) {
1565 // Include the current allocation, if any, and bytes that will be
1566 // pre-allocated to support collections, as "used".
1567 const size_t used_after_gc = used();
1568 const size_t capacity_after_gc = capacity();
1569 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1570
1571 // This is enforced in arguments.cpp.
1572 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1573 "otherwise the code below doesn't make sense");
1574
1575 // We don't have floating point command-line arguments
1576 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1577 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1578 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1579 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1580
1581 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1582 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1583
1584 // We have to be careful here as these two calculations can overflow
1585 // 32-bit size_t's.
1586 double used_after_gc_d = (double) used_after_gc;
1587 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1588 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1589
1590 // Let's make sure that they are both under the max heap size, which
1591 // by default will make them fit into a size_t.
1592 double desired_capacity_upper_bound = (double) max_heap_size;
1593 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1594 desired_capacity_upper_bound);
1595 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1596 desired_capacity_upper_bound);
1597
1598 // We can now safely turn them into size_t's.
1599 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1600 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1601
1602 // This assert only makes sense here, before we adjust them
1603 // with respect to the min and max heap size.
1604 assert(minimum_desired_capacity <= maximum_desired_capacity,
1605 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1606 "maximum_desired_capacity = "SIZE_FORMAT,
1607 minimum_desired_capacity, maximum_desired_capacity));
1608
1609 // Should not be greater than the heap max size. No need to adjust
1610 // it with respect to the heap min size as it's a lower bound (i.e.,
1611 // we'll try to make the capacity larger than it, not smaller).
1612 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1613 // Should not be less than the heap min size. No need to adjust it
1614 // with respect to the heap max size as it's an upper bound (i.e.,
1615 // we'll try to make the capacity smaller than it, not greater).
1616 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1617
1618 if (capacity_after_gc < minimum_desired_capacity) {
1619 // Don't expand unless it's significant
1620 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1621 ergo_verbose4(ErgoHeapSizing,
1622 "attempt heap expansion",
1623 ergo_format_reason("capacity lower than "
1624 "min desired capacity after Full GC")
1625 ergo_format_byte("capacity")
1626 ergo_format_byte("occupancy")
1627 ergo_format_byte_perc("min desired capacity"),
1628 capacity_after_gc, used_after_gc,
1629 minimum_desired_capacity, (double) MinHeapFreeRatio);
1630 expand(expand_bytes);
1631
1632 // No expansion, now see if we want to shrink
1633 } else if (capacity_after_gc > maximum_desired_capacity) {
1634 // Capacity too large, compute shrinking size
1635 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1636 ergo_verbose4(ErgoHeapSizing,
1637 "attempt heap shrinking",
1638 ergo_format_reason("capacity higher than "
1639 "max desired capacity after Full GC")
1640 ergo_format_byte("capacity")
1641 ergo_format_byte("occupancy")
1642 ergo_format_byte_perc("max desired capacity"),
1643 capacity_after_gc, used_after_gc,
1644 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1645 shrink(shrink_bytes);
1646 }
1647 }
1648
1649
1650 HeapWord*
1651 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1652 bool* succeeded) {
1653 assert_at_safepoint(true /* should_be_vm_thread */);
1654
1655 *succeeded = true;
1656 // Let's attempt the allocation first.
1657 HeapWord* result =
1658 attempt_allocation_at_safepoint(word_size,
1659 false /* expect_null_mutator_alloc_region */);
1660 if (result != NULL) {
1661 assert(*succeeded, "sanity");
1662 return result;
1663 }
1664
1665 // In a G1 heap, we're supposed to keep allocation from failing by
1666 // incremental pauses. Therefore, at least for now, we'll favor
1667 // expansion over collection. (This might change in the future if we can
1668 // do something smarter than full collection to satisfy a failed alloc.)
1669 result = expand_and_allocate(word_size);
1670 if (result != NULL) {
1671 assert(*succeeded, "sanity");
1672 return result;
1673 }
1674
1675 // Expansion didn't work, we'll try to do a Full GC.
1676 bool gc_succeeded = do_collection(false, /* explicit_gc */
1677 false, /* clear_all_soft_refs */
1678 word_size);
1679 if (!gc_succeeded) {
1680 *succeeded = false;
1681 return NULL;
1682 }
1683
1684 // Retry the allocation
1685 result = attempt_allocation_at_safepoint(word_size,
1686 true /* expect_null_mutator_alloc_region */);
1687 if (result != NULL) {
1688 assert(*succeeded, "sanity");
1689 return result;
1690 }
1691
1692 // Then, try a Full GC that will collect all soft references.
1693 gc_succeeded = do_collection(false, /* explicit_gc */
1694 true, /* clear_all_soft_refs */
1695 word_size);
1696 if (!gc_succeeded) {
1697 *succeeded = false;
1698 return NULL;
1699 }
1700
1701 // Retry the allocation once more
1702 result = attempt_allocation_at_safepoint(word_size,
1703 true /* expect_null_mutator_alloc_region */);
1704 if (result != NULL) {
1705 assert(*succeeded, "sanity");
1706 return result;
1707 }
1708
1709 assert(!collector_policy()->should_clear_all_soft_refs(),
1710 "Flag should have been handled and cleared prior to this point");
1711
1712 // What else? We might try synchronous finalization later. If the total
1713 // space available is large enough for the allocation, then a more
1714 // complete compaction phase than we've tried so far might be
1715 // appropriate.
1716 assert(*succeeded, "sanity");
1717 return NULL;
1718 }
1719
1720 // Attempting to expand the heap sufficiently
1721 // to support an allocation of the given "word_size". If
1722 // successful, perform the allocation and return the address of the
1723 // allocated block, or else "NULL".
1724
1725 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1726 assert_at_safepoint(true /* should_be_vm_thread */);
1727
1728 verify_region_sets_optional();
1729
1730 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1731 ergo_verbose1(ErgoHeapSizing,
1732 "attempt heap expansion",
1733 ergo_format_reason("allocation request failed")
1734 ergo_format_byte("allocation request"),
1735 word_size * HeapWordSize);
1736 if (expand(expand_bytes)) {
1737 _hrs.verify_optional();
1738 verify_region_sets_optional();
1739 return attempt_allocation_at_safepoint(word_size,
1740 false /* expect_null_mutator_alloc_region */);
1741 }
1742 return NULL;
1743 }
1744
1745 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1746 HeapWord* new_end) {
1747 assert(old_end != new_end, "don't call this otherwise");
1748 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1749
1750 // Update the committed mem region.
1751 _g1_committed.set_end(new_end);
1752 // Tell the card table about the update.
1753 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1754 // Tell the BOT about the update.
1755 _bot_shared->resize(_g1_committed.word_size());
1756 // Tell the hot card cache about the update
1757 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1758 }
1759
1760 bool G1CollectedHeap::expand(size_t expand_bytes) {
1761 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1762 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1763 HeapRegion::GrainBytes);
1764 ergo_verbose2(ErgoHeapSizing,
1765 "expand the heap",
1766 ergo_format_byte("requested expansion amount")
1767 ergo_format_byte("attempted expansion amount"),
1768 expand_bytes, aligned_expand_bytes);
1769
1770 if (_g1_storage.uncommitted_size() == 0) {
1771 ergo_verbose0(ErgoHeapSizing,
1772 "did not expand the heap",
1773 ergo_format_reason("heap already fully expanded"));
1774 return false;
1775 }
1776
1777 // First commit the memory.
1778 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1779 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1780 if (successful) {
1781 // Then propagate this update to the necessary data structures.
1782 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1783 update_committed_space(old_end, new_end);
1784
1785 FreeRegionList expansion_list("Local Expansion List");
1786 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1787 assert(mr.start() == old_end, "post-condition");
1788 // mr might be a smaller region than what was requested if
1789 // expand_by() was unable to allocate the HeapRegion instances
1790 assert(mr.end() <= new_end, "post-condition");
1791
1792 size_t actual_expand_bytes = mr.byte_size();
1793 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1794 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1795 "post-condition");
1796 if (actual_expand_bytes < aligned_expand_bytes) {
1797 // We could not expand _hrs to the desired size. In this case we
1798 // need to shrink the committed space accordingly.
1799 assert(mr.end() < new_end, "invariant");
1800
1801 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1802 // First uncommit the memory.
1803 _g1_storage.shrink_by(diff_bytes);
1804 // Then propagate this update to the necessary data structures.
1805 update_committed_space(new_end, mr.end());
1806 }
1807 _free_list.add_as_tail(&expansion_list);
1808
1809 if (_hr_printer.is_active()) {
1810 HeapWord* curr = mr.start();
1811 while (curr < mr.end()) {
1812 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1813 _hr_printer.commit(curr, curr_end);
1814 curr = curr_end;
1815 }
1816 assert(curr == mr.end(), "post-condition");
1817 }
1818 g1_policy()->record_new_heap_size(n_regions());
1819 } else {
1820 ergo_verbose0(ErgoHeapSizing,
1821 "did not expand the heap",
1822 ergo_format_reason("heap expansion operation failed"));
1823 // The expansion of the virtual storage space was unsuccessful.
1824 // Let's see if it was because we ran out of swap.
1825 if (G1ExitOnExpansionFailure &&
1826 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1827 // We had head room...
1828 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1829 }
1830 }
1831 return successful;
1832 }
1833
1834 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1835 size_t aligned_shrink_bytes =
1836 ReservedSpace::page_align_size_down(shrink_bytes);
1837 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1838 HeapRegion::GrainBytes);
1839 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1840
1841 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1842 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1843 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1844
1845 ergo_verbose3(ErgoHeapSizing,
1846 "shrink the heap",
1847 ergo_format_byte("requested shrinking amount")
1848 ergo_format_byte("aligned shrinking amount")
1849 ergo_format_byte("attempted shrinking amount"),
1850 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1851 if (num_regions_removed > 0) {
1852 _g1_storage.shrink_by(shrunk_bytes);
1853 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1854
1855 if (_hr_printer.is_active()) {
1856 HeapWord* curr = old_end;
1857 while (curr > new_end) {
1858 HeapWord* curr_end = curr;
1859 curr -= HeapRegion::GrainWords;
1860 _hr_printer.uncommit(curr, curr_end);
1861 }
1862 }
1863
1864 _expansion_regions += num_regions_removed;
1865 update_committed_space(old_end, new_end);
1866 HeapRegionRemSet::shrink_heap(n_regions());
1867 g1_policy()->record_new_heap_size(n_regions());
1868 } else {
1869 ergo_verbose0(ErgoHeapSizing,
1870 "did not shrink the heap",
1871 ergo_format_reason("heap shrinking operation failed"));
1872 }
1873 }
1874
1875 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1876 verify_region_sets_optional();
1877
1878 // We should only reach here at the end of a Full GC which means we
1879 // should not not be holding to any GC alloc regions. The method
1880 // below will make sure of that and do any remaining clean up.
1881 abandon_gc_alloc_regions();
1882
1883 // Instead of tearing down / rebuilding the free lists here, we
1884 // could instead use the remove_all_pending() method on free_list to
1885 // remove only the ones that we need to remove.
1886 tear_down_region_sets(true /* free_list_only */);
1887 shrink_helper(shrink_bytes);
1888 rebuild_region_sets(true /* free_list_only */);
1889
1890 _hrs.verify_optional();
1891 verify_region_sets_optional();
1892 }
1893
1894 // Public methods.
1895
1896 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1897 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1898 #endif // _MSC_VER
1899
1900
1901 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1902 SharedHeap(policy_),
1903 _g1_policy(policy_),
1904 _dirty_card_queue_set(false),
1905 _into_cset_dirty_card_queue_set(false),
1906 _is_alive_closure_cm(this),
1907 _is_alive_closure_stw(this),
1908 _ref_processor_cm(NULL),
1909 _ref_processor_stw(NULL),
1910 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1911 _bot_shared(NULL),
1912 _evac_failure_scan_stack(NULL),
1913 _mark_in_progress(false),
1914 _cg1r(NULL), _summary_bytes_used(0),
1915 _g1mm(NULL),
1916 _refine_cte_cl(NULL),
1917 _full_collection(false),
1918 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1919 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1920 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1921 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1922 _free_regions_coming(false),
1923 _young_list(new YoungList(this)),
1924 _gc_time_stamp(0),
1925 _retained_old_gc_alloc_region(NULL),
1926 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1927 _old_plab_stats(OldPLABSize, PLABWeight),
1928 _expand_heap_after_alloc_failure(true),
1929 _surviving_young_words(NULL),
1930 _old_marking_cycles_started(0),
1931 _old_marking_cycles_completed(0),
1932 _concurrent_cycle_started(false),
1933 _in_cset_fast_test(),
1934 _dirty_cards_region_list(NULL),
1935 _worker_cset_start_region(NULL),
1936 _worker_cset_start_region_time_stamp(NULL),
1937 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1938 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1939 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1940 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1941
1942 _g1h = this;
1943 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1944 vm_exit_during_initialization("Failed necessary allocation.");
1945 }
1946
1947 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1948
1949 int n_queues = MAX2((int)ParallelGCThreads, 1);
1950 _task_queues = new RefToScanQueueSet(n_queues);
1951
1952 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1953 assert(n_rem_sets > 0, "Invariant.");
1954
1955 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1956 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1957 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1958
1959 for (int i = 0; i < n_queues; i++) {
1960 RefToScanQueue* q = new RefToScanQueue();
1961 q->initialize();
1962 _task_queues->register_queue(i, q);
1963 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1964 }
1965 clear_cset_start_regions();
1966
1967 // Initialize the G1EvacuationFailureALot counters and flags.
1968 NOT_PRODUCT(reset_evacuation_should_fail();)
1969
1970 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1971 }
1972
1973 jint G1CollectedHeap::initialize() {
1974 CollectedHeap::pre_initialize();
1975 os::enable_vtime();
1976
1977 G1Log::init();
1978
1979 // Necessary to satisfy locking discipline assertions.
1980
1981 MutexLocker x(Heap_lock);
1982
1983 // We have to initialize the printer before committing the heap, as
1984 // it will be used then.
1985 _hr_printer.set_active(G1PrintHeapRegions);
1986
1987 // While there are no constraints in the GC code that HeapWordSize
1988 // be any particular value, there are multiple other areas in the
1989 // system which believe this to be true (e.g. oop->object_size in some
1990 // cases incorrectly returns the size in wordSize units rather than
1991 // HeapWordSize).
1992 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1993
1994 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1995 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1996 size_t heap_alignment = collector_policy()->heap_alignment();
1997
1998 // Ensure that the sizes are properly aligned.
1999 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2000 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2001 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2002
2003 _cg1r = new ConcurrentG1Refine(this);
2004
2005 // Reserve the maximum.
2006
2007 // When compressed oops are enabled, the preferred heap base
2008 // is calculated by subtracting the requested size from the
2009 // 32Gb boundary and using the result as the base address for
2010 // heap reservation. If the requested size is not aligned to
2011 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2012 // into the ReservedHeapSpace constructor) then the actual
2013 // base of the reserved heap may end up differing from the
2014 // address that was requested (i.e. the preferred heap base).
2015 // If this happens then we could end up using a non-optimal
2016 // compressed oops mode.
2017
2018 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2019 heap_alignment);
2020
2021 // It is important to do this in a way such that concurrent readers can't
2022 // temporarily think something is in the heap. (I've actually seen this
2023 // happen in asserts: DLD.)
2024 _reserved.set_word_size(0);
2025 _reserved.set_start((HeapWord*)heap_rs.base());
2026 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2027
2028 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2029
2030 // Create the gen rem set (and barrier set) for the entire reserved region.
2031 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2032 set_barrier_set(rem_set()->bs());
2033 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2034 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2035 return JNI_ENOMEM;
2036 }
2037
2038 // Also create a G1 rem set.
2039 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2040
2041 // Carve out the G1 part of the heap.
2042
2043 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2044 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2045 g1_rs.size()/HeapWordSize);
2046
2047 _g1_storage.initialize(g1_rs, 0);
2048 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2049 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2050 (HeapWord*) _g1_reserved.end());
2051 assert(_hrs.max_length() == _expansion_regions,
2052 err_msg("max length: %u expansion regions: %u",
2053 _hrs.max_length(), _expansion_regions));
2054
2055 // Do later initialization work for concurrent refinement.
2056 _cg1r->init();
2057
2058 // 6843694 - ensure that the maximum region index can fit
2059 // in the remembered set structures.
2060 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2061 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2062
2063 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2064 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2065 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2066 "too many cards per region");
2067
2068 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2069
2070 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2071 heap_word_size(init_byte_size));
2072
2073 _g1h = this;
2074
2075 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2076
2077 // Create the ConcurrentMark data structure and thread.
2078 // (Must do this late, so that "max_regions" is defined.)
2079 _cm = new ConcurrentMark(this, heap_rs);
2080 if (_cm == NULL || !_cm->completed_initialization()) {
2081 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2082 return JNI_ENOMEM;
2083 }
2084 _cmThread = _cm->cmThread();
2085
2086 // Initialize the from_card cache structure of HeapRegionRemSet.
2087 HeapRegionRemSet::init_heap(max_regions());
2088
2089 // Now expand into the initial heap size.
2090 if (!expand(init_byte_size)) {
2091 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2092 return JNI_ENOMEM;
2093 }
2094
2095 // Perform any initialization actions delegated to the policy.
2096 g1_policy()->init();
2097
2098 _refine_cte_cl =
2099 new RefineCardTableEntryClosure(g1_rem_set(),
2100 concurrent_g1_refine());
2101 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2102
2103 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2104 SATB_Q_FL_lock,
2105 G1SATBProcessCompletedThreshold,
2106 Shared_SATB_Q_lock);
2107
2108 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2109 DirtyCardQ_FL_lock,
2110 concurrent_g1_refine()->yellow_zone(),
2111 concurrent_g1_refine()->red_zone(),
2112 Shared_DirtyCardQ_lock);
2113
2114 if (G1DeferredRSUpdate) {
2115 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2116 DirtyCardQ_FL_lock,
2117 -1, // never trigger processing
2118 -1, // no limit on length
2119 Shared_DirtyCardQ_lock,
2120 &JavaThread::dirty_card_queue_set());
2121 }
2122
2123 // Initialize the card queue set used to hold cards containing
2124 // references into the collection set.
2125 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2126 DirtyCardQ_FL_lock,
2127 -1, // never trigger processing
2128 -1, // no limit on length
2129 Shared_DirtyCardQ_lock,
2130 &JavaThread::dirty_card_queue_set());
2131
2132 // In case we're keeping closure specialization stats, initialize those
2133 // counts and that mechanism.
2134 SpecializationStats::clear();
2135
2136 // Here we allocate the dummy full region that is required by the
2137 // G1AllocRegion class. If we don't pass an address in the reserved
2138 // space here, lots of asserts fire.
2139
2140 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2141 _g1_reserved.start());
2142 // We'll re-use the same region whether the alloc region will
2143 // require BOT updates or not and, if it doesn't, then a non-young
2144 // region will complain that it cannot support allocations without
2145 // BOT updates. So we'll tag the dummy region as young to avoid that.
2146 dummy_region->set_young();
2147 // Make sure it's full.
2148 dummy_region->set_top(dummy_region->end());
2149 G1AllocRegion::setup(this, dummy_region);
2150
2151 init_mutator_alloc_region();
2152
2153 // Do create of the monitoring and management support so that
2154 // values in the heap have been properly initialized.
2155 _g1mm = new G1MonitoringSupport(this);
2156
2157 G1StringDedup::initialize();
2158
2159 return JNI_OK;
2160 }
2161
2162 void G1CollectedHeap::stop() {
2163 // Stop all concurrent threads. We do this to make sure these threads
2164 // do not continue to execute and access resources (e.g. gclog_or_tty)
2165 // that are destroyed during shutdown.
2166 _cg1r->stop();
2167 _cmThread->stop();
2168 if (G1StringDedup::is_enabled()) {
2169 G1StringDedup::stop();
2170 }
2171 }
2172
2173 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2174 return HeapRegion::max_region_size();
2175 }
2176
2177 void G1CollectedHeap::ref_processing_init() {
2178 // Reference processing in G1 currently works as follows:
2179 //
2180 // * There are two reference processor instances. One is
2181 // used to record and process discovered references
2182 // during concurrent marking; the other is used to
2183 // record and process references during STW pauses
2184 // (both full and incremental).
2185 // * Both ref processors need to 'span' the entire heap as
2186 // the regions in the collection set may be dotted around.
2187 //
2188 // * For the concurrent marking ref processor:
2189 // * Reference discovery is enabled at initial marking.
2190 // * Reference discovery is disabled and the discovered
2191 // references processed etc during remarking.
2192 // * Reference discovery is MT (see below).
2193 // * Reference discovery requires a barrier (see below).
2194 // * Reference processing may or may not be MT
2195 // (depending on the value of ParallelRefProcEnabled
2196 // and ParallelGCThreads).
2197 // * A full GC disables reference discovery by the CM
2198 // ref processor and abandons any entries on it's
2199 // discovered lists.
2200 //
2201 // * For the STW processor:
2202 // * Non MT discovery is enabled at the start of a full GC.
2203 // * Processing and enqueueing during a full GC is non-MT.
2204 // * During a full GC, references are processed after marking.
2205 //
2206 // * Discovery (may or may not be MT) is enabled at the start
2207 // of an incremental evacuation pause.
2208 // * References are processed near the end of a STW evacuation pause.
2209 // * For both types of GC:
2210 // * Discovery is atomic - i.e. not concurrent.
2211 // * Reference discovery will not need a barrier.
2212
2213 SharedHeap::ref_processing_init();
2214 MemRegion mr = reserved_region();
2215
2216 // Concurrent Mark ref processor
2217 _ref_processor_cm =
2218 new ReferenceProcessor(mr, // span
2219 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2220 // mt processing
2221 (int) ParallelGCThreads,
2222 // degree of mt processing
2223 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2224 // mt discovery
2225 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2226 // degree of mt discovery
2227 false,
2228 // Reference discovery is not atomic
2229 &_is_alive_closure_cm);
2230 // is alive closure
2231 // (for efficiency/performance)
2232
2233 // STW ref processor
2234 _ref_processor_stw =
2235 new ReferenceProcessor(mr, // span
2236 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2237 // mt processing
2238 MAX2((int)ParallelGCThreads, 1),
2239 // degree of mt processing
2240 (ParallelGCThreads > 1),
2241 // mt discovery
2242 MAX2((int)ParallelGCThreads, 1),
2243 // degree of mt discovery
2244 true,
2245 // Reference discovery is atomic
2246 &_is_alive_closure_stw);
2247 // is alive closure
2248 // (for efficiency/performance)
2249 }
2250
2251 size_t G1CollectedHeap::capacity() const {
2252 return _g1_committed.byte_size();
2253 }
2254
2255 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2256 assert(!hr->continuesHumongous(), "pre-condition");
2257 hr->reset_gc_time_stamp();
2258 if (hr->startsHumongous()) {
2259 uint first_index = hr->hrs_index() + 1;
2260 uint last_index = hr->last_hc_index();
2261 for (uint i = first_index; i < last_index; i += 1) {
2262 HeapRegion* chr = region_at(i);
2263 assert(chr->continuesHumongous(), "sanity");
2264 chr->reset_gc_time_stamp();
2265 }
2266 }
2267 }
2268
2269 #ifndef PRODUCT
2270 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2271 private:
2272 unsigned _gc_time_stamp;
2273 bool _failures;
2274
2275 public:
2276 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2277 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2278
2279 virtual bool doHeapRegion(HeapRegion* hr) {
2280 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2281 if (_gc_time_stamp != region_gc_time_stamp) {
2282 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2283 "expected %d", HR_FORMAT_PARAMS(hr),
2284 region_gc_time_stamp, _gc_time_stamp);
2285 _failures = true;
2286 }
2287 return false;
2288 }
2289
2290 bool failures() { return _failures; }
2291 };
2292
2293 void G1CollectedHeap::check_gc_time_stamps() {
2294 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2295 heap_region_iterate(&cl);
2296 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2297 }
2298 #endif // PRODUCT
2299
2300 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2301 DirtyCardQueue* into_cset_dcq,
2302 bool concurrent,
2303 uint worker_i) {
2304 // Clean cards in the hot card cache
2305 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2306 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2307
2308 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2309 int n_completed_buffers = 0;
2310 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2311 n_completed_buffers++;
2312 }
2313 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2314 dcqs.clear_n_completed_buffers();
2315 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2316 }
2317
2318
2319 // Computes the sum of the storage used by the various regions.
2320
2321 size_t G1CollectedHeap::used() const {
2322 assert(Heap_lock->owner() != NULL,
2323 "Should be owned on this thread's behalf.");
2324 size_t result = _summary_bytes_used;
2325 // Read only once in case it is set to NULL concurrently
2326 HeapRegion* hr = _mutator_alloc_region.get();
2327 if (hr != NULL)
2328 result += hr->used();
2329 return result;
2330 }
2331
2332 size_t G1CollectedHeap::used_unlocked() const {
2333 size_t result = _summary_bytes_used;
2334 return result;
2335 }
2336
2337 class SumUsedClosure: public HeapRegionClosure {
2338 size_t _used;
2339 public:
2340 SumUsedClosure() : _used(0) {}
2341 bool doHeapRegion(HeapRegion* r) {
2342 if (!r->continuesHumongous()) {
2343 _used += r->used();
2344 }
2345 return false;
2346 }
2347 size_t result() { return _used; }
2348 };
2349
2350 size_t G1CollectedHeap::recalculate_used() const {
2351 double recalculate_used_start = os::elapsedTime();
2352
2353 SumUsedClosure blk;
2354 heap_region_iterate(&blk);
2355
2356 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2357 return blk.result();
2358 }
2359
2360 size_t G1CollectedHeap::unsafe_max_alloc() {
2361 if (free_regions() > 0) return HeapRegion::GrainBytes;
2362 // otherwise, is there space in the current allocation region?
2363
2364 // We need to store the current allocation region in a local variable
2365 // here. The problem is that this method doesn't take any locks and
2366 // there may be other threads which overwrite the current allocation
2367 // region field. attempt_allocation(), for example, sets it to NULL
2368 // and this can happen *after* the NULL check here but before the call
2369 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2370 // to be a problem in the optimized build, since the two loads of the
2371 // current allocation region field are optimized away.
2372 HeapRegion* hr = _mutator_alloc_region.get();
2373 if (hr == NULL) {
2374 return 0;
2375 }
2376 return hr->free();
2377 }
2378
2379 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2380 switch (cause) {
2381 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2382 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2383 case GCCause::_g1_humongous_allocation: return true;
2384 default: return false;
2385 }
2386 }
2387
2388 #ifndef PRODUCT
2389 void G1CollectedHeap::allocate_dummy_regions() {
2390 // Let's fill up most of the region
2391 size_t word_size = HeapRegion::GrainWords - 1024;
2392 // And as a result the region we'll allocate will be humongous.
2393 guarantee(isHumongous(word_size), "sanity");
2394
2395 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2396 // Let's use the existing mechanism for the allocation
2397 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2398 if (dummy_obj != NULL) {
2399 MemRegion mr(dummy_obj, word_size);
2400 CollectedHeap::fill_with_object(mr);
2401 } else {
2402 // If we can't allocate once, we probably cannot allocate
2403 // again. Let's get out of the loop.
2404 break;
2405 }
2406 }
2407 }
2408 #endif // !PRODUCT
2409
2410 void G1CollectedHeap::increment_old_marking_cycles_started() {
2411 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2412 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2413 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2414 _old_marking_cycles_started, _old_marking_cycles_completed));
2415
2416 _old_marking_cycles_started++;
2417 }
2418
2419 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2420 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2421
2422 // We assume that if concurrent == true, then the caller is a
2423 // concurrent thread that was joined the Suspendible Thread
2424 // Set. If there's ever a cheap way to check this, we should add an
2425 // assert here.
2426
2427 // Given that this method is called at the end of a Full GC or of a
2428 // concurrent cycle, and those can be nested (i.e., a Full GC can
2429 // interrupt a concurrent cycle), the number of full collections
2430 // completed should be either one (in the case where there was no
2431 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2432 // behind the number of full collections started.
2433
2434 // This is the case for the inner caller, i.e. a Full GC.
2435 assert(concurrent ||
2436 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2437 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2438 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2439 "is inconsistent with _old_marking_cycles_completed = %u",
2440 _old_marking_cycles_started, _old_marking_cycles_completed));
2441
2442 // This is the case for the outer caller, i.e. the concurrent cycle.
2443 assert(!concurrent ||
2444 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2445 err_msg("for outer caller (concurrent cycle): "
2446 "_old_marking_cycles_started = %u "
2447 "is inconsistent with _old_marking_cycles_completed = %u",
2448 _old_marking_cycles_started, _old_marking_cycles_completed));
2449
2450 _old_marking_cycles_completed += 1;
2451
2452 // We need to clear the "in_progress" flag in the CM thread before
2453 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2454 // is set) so that if a waiter requests another System.gc() it doesn't
2455 // incorrectly see that a marking cycle is still in progress.
2456 if (concurrent) {
2457 _cmThread->clear_in_progress();
2458 }
2459
2460 // This notify_all() will ensure that a thread that called
2461 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2462 // and it's waiting for a full GC to finish will be woken up. It is
2463 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2464 FullGCCount_lock->notify_all();
2465 }
2466
2467 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2468 _concurrent_cycle_started = true;
2469 _gc_timer_cm->register_gc_start(start_time);
2470
2471 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2472 trace_heap_before_gc(_gc_tracer_cm);
2473 }
2474
2475 void G1CollectedHeap::register_concurrent_cycle_end() {
2476 if (_concurrent_cycle_started) {
2477 if (_cm->has_aborted()) {
2478 _gc_tracer_cm->report_concurrent_mode_failure();
2479 }
2480
2481 _gc_timer_cm->register_gc_end();
2482 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2483
2484 _concurrent_cycle_started = false;
2485 }
2486 }
2487
2488 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2489 if (_concurrent_cycle_started) {
2490 trace_heap_after_gc(_gc_tracer_cm);
2491 }
2492 }
2493
2494 G1YCType G1CollectedHeap::yc_type() {
2495 bool is_young = g1_policy()->gcs_are_young();
2496 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2497 bool is_during_mark = mark_in_progress();
2498
2499 if (is_initial_mark) {
2500 return InitialMark;
2501 } else if (is_during_mark) {
2502 return DuringMark;
2503 } else if (is_young) {
2504 return Normal;
2505 } else {
2506 return Mixed;
2507 }
2508 }
2509
2510 void G1CollectedHeap::collect(GCCause::Cause cause) {
2511 assert_heap_not_locked();
2512
2513 unsigned int gc_count_before;
2514 unsigned int old_marking_count_before;
2515 bool retry_gc;
2516
2517 do {
2518 retry_gc = false;
2519
2520 {
2521 MutexLocker ml(Heap_lock);
2522
2523 // Read the GC count while holding the Heap_lock
2524 gc_count_before = total_collections();
2525 old_marking_count_before = _old_marking_cycles_started;
2526 }
2527
2528 if (should_do_concurrent_full_gc(cause)) {
2529 // Schedule an initial-mark evacuation pause that will start a
2530 // concurrent cycle. We're setting word_size to 0 which means that
2531 // we are not requesting a post-GC allocation.
2532 VM_G1IncCollectionPause op(gc_count_before,
2533 0, /* word_size */
2534 true, /* should_initiate_conc_mark */
2535 g1_policy()->max_pause_time_ms(),
2536 cause);
2537
2538 VMThread::execute(&op);
2539 if (!op.pause_succeeded()) {
2540 if (old_marking_count_before == _old_marking_cycles_started) {
2541 retry_gc = op.should_retry_gc();
2542 } else {
2543 // A Full GC happened while we were trying to schedule the
2544 // initial-mark GC. No point in starting a new cycle given
2545 // that the whole heap was collected anyway.
2546 }
2547
2548 if (retry_gc) {
2549 if (GC_locker::is_active_and_needs_gc()) {
2550 GC_locker::stall_until_clear();
2551 }
2552 }
2553 }
2554 } else {
2555 if (cause == GCCause::_gc_locker
2556 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2557
2558 // Schedule a standard evacuation pause. We're setting word_size
2559 // to 0 which means that we are not requesting a post-GC allocation.
2560 VM_G1IncCollectionPause op(gc_count_before,
2561 0, /* word_size */
2562 false, /* should_initiate_conc_mark */
2563 g1_policy()->max_pause_time_ms(),
2564 cause);
2565 VMThread::execute(&op);
2566 } else {
2567 // Schedule a Full GC.
2568 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2569 VMThread::execute(&op);
2570 }
2571 }
2572 } while (retry_gc);
2573 }
2574
2575 bool G1CollectedHeap::is_in(const void* p) const {
2576 if (_g1_committed.contains(p)) {
2577 // Given that we know that p is in the committed space,
2578 // heap_region_containing_raw() should successfully
2579 // return the containing region.
2580 HeapRegion* hr = heap_region_containing_raw(p);
2581 return hr->is_in(p);
2582 } else {
2583 return false;
2584 }
2585 }
2586
2587 // Iteration functions.
2588
2589 // Iterates an OopClosure over all ref-containing fields of objects
2590 // within a HeapRegion.
2591
2592 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2593 MemRegion _mr;
2594 ExtendedOopClosure* _cl;
2595 public:
2596 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2597 : _mr(mr), _cl(cl) {}
2598 bool doHeapRegion(HeapRegion* r) {
2599 if (!r->continuesHumongous()) {
2600 r->oop_iterate(_cl);
2601 }
2602 return false;
2603 }
2604 };
2605
2606 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2607 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2608 heap_region_iterate(&blk);
2609 }
2610
2611 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2612 IterateOopClosureRegionClosure blk(mr, cl);
2613 heap_region_iterate(&blk);
2614 }
2615
2616 // Iterates an ObjectClosure over all objects within a HeapRegion.
2617
2618 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2619 ObjectClosure* _cl;
2620 public:
2621 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2622 bool doHeapRegion(HeapRegion* r) {
2623 if (! r->continuesHumongous()) {
2624 r->object_iterate(_cl);
2625 }
2626 return false;
2627 }
2628 };
2629
2630 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2631 IterateObjectClosureRegionClosure blk(cl);
2632 heap_region_iterate(&blk);
2633 }
2634
2635 // Calls a SpaceClosure on a HeapRegion.
2636
2637 class SpaceClosureRegionClosure: public HeapRegionClosure {
2638 SpaceClosure* _cl;
2639 public:
2640 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2641 bool doHeapRegion(HeapRegion* r) {
2642 _cl->do_space(r);
2643 return false;
2644 }
2645 };
2646
2647 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2648 SpaceClosureRegionClosure blk(cl);
2649 heap_region_iterate(&blk);
2650 }
2651
2652 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2653 _hrs.iterate(cl);
2654 }
2655
2656 void
2657 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2658 uint worker_id,
2659 uint no_of_par_workers,
2660 jint claim_value) {
2661 const uint regions = n_regions();
2662 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2663 no_of_par_workers :
2664 1);
2665 assert(UseDynamicNumberOfGCThreads ||
2666 no_of_par_workers == workers()->total_workers(),
2667 "Non dynamic should use fixed number of workers");
2668 // try to spread out the starting points of the workers
2669 const HeapRegion* start_hr =
2670 start_region_for_worker(worker_id, no_of_par_workers);
2671 const uint start_index = start_hr->hrs_index();
2672
2673 // each worker will actually look at all regions
2674 for (uint count = 0; count < regions; ++count) {
2675 const uint index = (start_index + count) % regions;
2676 assert(0 <= index && index < regions, "sanity");
2677 HeapRegion* r = region_at(index);
2678 // we'll ignore "continues humongous" regions (we'll process them
2679 // when we come across their corresponding "start humongous"
2680 // region) and regions already claimed
2681 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2682 continue;
2683 }
2684 // OK, try to claim it
2685 if (r->claimHeapRegion(claim_value)) {
2686 // success!
2687 assert(!r->continuesHumongous(), "sanity");
2688 if (r->startsHumongous()) {
2689 // If the region is "starts humongous" we'll iterate over its
2690 // "continues humongous" first; in fact we'll do them
2691 // first. The order is important. In on case, calling the
2692 // closure on the "starts humongous" region might de-allocate
2693 // and clear all its "continues humongous" regions and, as a
2694 // result, we might end up processing them twice. So, we'll do
2695 // them first (notice: most closures will ignore them anyway) and
2696 // then we'll do the "starts humongous" region.
2697 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2698 HeapRegion* chr = region_at(ch_index);
2699
2700 // if the region has already been claimed or it's not
2701 // "continues humongous" we're done
2702 if (chr->claim_value() == claim_value ||
2703 !chr->continuesHumongous()) {
2704 break;
2705 }
2706
2707 // No one should have claimed it directly. We can given
2708 // that we claimed its "starts humongous" region.
2709 assert(chr->claim_value() != claim_value, "sanity");
2710 assert(chr->humongous_start_region() == r, "sanity");
2711
2712 if (chr->claimHeapRegion(claim_value)) {
2713 // we should always be able to claim it; no one else should
2714 // be trying to claim this region
2715
2716 bool res2 = cl->doHeapRegion(chr);
2717 assert(!res2, "Should not abort");
2718
2719 // Right now, this holds (i.e., no closure that actually
2720 // does something with "continues humongous" regions
2721 // clears them). We might have to weaken it in the future,
2722 // but let's leave these two asserts here for extra safety.
2723 assert(chr->continuesHumongous(), "should still be the case");
2724 assert(chr->humongous_start_region() == r, "sanity");
2725 } else {
2726 guarantee(false, "we should not reach here");
2727 }
2728 }
2729 }
2730
2731 assert(!r->continuesHumongous(), "sanity");
2732 bool res = cl->doHeapRegion(r);
2733 assert(!res, "Should not abort");
2734 }
2735 }
2736 }
2737
2738 class ResetClaimValuesClosure: public HeapRegionClosure {
2739 public:
2740 bool doHeapRegion(HeapRegion* r) {
2741 r->set_claim_value(HeapRegion::InitialClaimValue);
2742 return false;
2743 }
2744 };
2745
2746 void G1CollectedHeap::reset_heap_region_claim_values() {
2747 ResetClaimValuesClosure blk;
2748 heap_region_iterate(&blk);
2749 }
2750
2751 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2752 ResetClaimValuesClosure blk;
2753 collection_set_iterate(&blk);
2754 }
2755
2756 #ifdef ASSERT
2757 // This checks whether all regions in the heap have the correct claim
2758 // value. I also piggy-backed on this a check to ensure that the
2759 // humongous_start_region() information on "continues humongous"
2760 // regions is correct.
2761
2762 class CheckClaimValuesClosure : public HeapRegionClosure {
2763 private:
2764 jint _claim_value;
2765 uint _failures;
2766 HeapRegion* _sh_region;
2767
2768 public:
2769 CheckClaimValuesClosure(jint claim_value) :
2770 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2771 bool doHeapRegion(HeapRegion* r) {
2772 if (r->claim_value() != _claim_value) {
2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2774 "claim value = %d, should be %d",
2775 HR_FORMAT_PARAMS(r),
2776 r->claim_value(), _claim_value);
2777 ++_failures;
2778 }
2779 if (!r->isHumongous()) {
2780 _sh_region = NULL;
2781 } else if (r->startsHumongous()) {
2782 _sh_region = r;
2783 } else if (r->continuesHumongous()) {
2784 if (r->humongous_start_region() != _sh_region) {
2785 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2786 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2787 HR_FORMAT_PARAMS(r),
2788 r->humongous_start_region(),
2789 _sh_region);
2790 ++_failures;
2791 }
2792 }
2793 return false;
2794 }
2795 uint failures() { return _failures; }
2796 };
2797
2798 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2799 CheckClaimValuesClosure cl(claim_value);
2800 heap_region_iterate(&cl);
2801 return cl.failures() == 0;
2802 }
2803
2804 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2805 private:
2806 jint _claim_value;
2807 uint _failures;
2808
2809 public:
2810 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2811 _claim_value(claim_value), _failures(0) { }
2812
2813 uint failures() { return _failures; }
2814
2815 bool doHeapRegion(HeapRegion* hr) {
2816 assert(hr->in_collection_set(), "how?");
2817 assert(!hr->isHumongous(), "H-region in CSet");
2818 if (hr->claim_value() != _claim_value) {
2819 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2820 "claim value = %d, should be %d",
2821 HR_FORMAT_PARAMS(hr),
2822 hr->claim_value(), _claim_value);
2823 _failures += 1;
2824 }
2825 return false;
2826 }
2827 };
2828
2829 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2830 CheckClaimValuesInCSetHRClosure cl(claim_value);
2831 collection_set_iterate(&cl);
2832 return cl.failures() == 0;
2833 }
2834 #endif // ASSERT
2835
2836 // Clear the cached CSet starting regions and (more importantly)
2837 // the time stamps. Called when we reset the GC time stamp.
2838 void G1CollectedHeap::clear_cset_start_regions() {
2839 assert(_worker_cset_start_region != NULL, "sanity");
2840 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2841
2842 int n_queues = MAX2((int)ParallelGCThreads, 1);
2843 for (int i = 0; i < n_queues; i++) {
2844 _worker_cset_start_region[i] = NULL;
2845 _worker_cset_start_region_time_stamp[i] = 0;
2846 }
2847 }
2848
2849 // Given the id of a worker, obtain or calculate a suitable
2850 // starting region for iterating over the current collection set.
2851 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2852 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2853
2854 HeapRegion* result = NULL;
2855 unsigned gc_time_stamp = get_gc_time_stamp();
2856
2857 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2858 // Cached starting region for current worker was set
2859 // during the current pause - so it's valid.
2860 // Note: the cached starting heap region may be NULL
2861 // (when the collection set is empty).
2862 result = _worker_cset_start_region[worker_i];
2863 assert(result == NULL || result->in_collection_set(), "sanity");
2864 return result;
2865 }
2866
2867 // The cached entry was not valid so let's calculate
2868 // a suitable starting heap region for this worker.
2869
2870 // We want the parallel threads to start their collection
2871 // set iteration at different collection set regions to
2872 // avoid contention.
2873 // If we have:
2874 // n collection set regions
2875 // p threads
2876 // Then thread t will start at region floor ((t * n) / p)
2877
2878 result = g1_policy()->collection_set();
2879 if (G1CollectedHeap::use_parallel_gc_threads()) {
2880 uint cs_size = g1_policy()->cset_region_length();
2881 uint active_workers = workers()->active_workers();
2882 assert(UseDynamicNumberOfGCThreads ||
2883 active_workers == workers()->total_workers(),
2884 "Unless dynamic should use total workers");
2885
2886 uint end_ind = (cs_size * worker_i) / active_workers;
2887 uint start_ind = 0;
2888
2889 if (worker_i > 0 &&
2890 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2891 // Previous workers starting region is valid
2892 // so let's iterate from there
2893 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2894 result = _worker_cset_start_region[worker_i - 1];
2895 }
2896
2897 for (uint i = start_ind; i < end_ind; i++) {
2898 result = result->next_in_collection_set();
2899 }
2900 }
2901
2902 // Note: the calculated starting heap region may be NULL
2903 // (when the collection set is empty).
2904 assert(result == NULL || result->in_collection_set(), "sanity");
2905 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2906 "should be updated only once per pause");
2907 _worker_cset_start_region[worker_i] = result;
2908 OrderAccess::storestore();
2909 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2910 return result;
2911 }
2912
2913 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2914 uint no_of_par_workers) {
2915 uint worker_num =
2916 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2917 assert(UseDynamicNumberOfGCThreads ||
2918 no_of_par_workers == workers()->total_workers(),
2919 "Non dynamic should use fixed number of workers");
2920 const uint start_index = n_regions() * worker_i / worker_num;
2921 return region_at(start_index);
2922 }
2923
2924 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2925 HeapRegion* r = g1_policy()->collection_set();
2926 while (r != NULL) {
2927 HeapRegion* next = r->next_in_collection_set();
2928 if (cl->doHeapRegion(r)) {
2929 cl->incomplete();
2930 return;
2931 }
2932 r = next;
2933 }
2934 }
2935
2936 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2937 HeapRegionClosure *cl) {
2938 if (r == NULL) {
2939 // The CSet is empty so there's nothing to do.
2940 return;
2941 }
2942
2943 assert(r->in_collection_set(),
2944 "Start region must be a member of the collection set.");
2945 HeapRegion* cur = r;
2946 while (cur != NULL) {
2947 HeapRegion* next = cur->next_in_collection_set();
2948 if (cl->doHeapRegion(cur) && false) {
2949 cl->incomplete();
2950 return;
2951 }
2952 cur = next;
2953 }
2954 cur = g1_policy()->collection_set();
2955 while (cur != r) {
2956 HeapRegion* next = cur->next_in_collection_set();
2957 if (cl->doHeapRegion(cur) && false) {
2958 cl->incomplete();
2959 return;
2960 }
2961 cur = next;
2962 }
2963 }
2964
2965 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2966 return n_regions() > 0 ? region_at(0) : NULL;
2967 }
2968
2969
2970 Space* G1CollectedHeap::space_containing(const void* addr) const {
2971 Space* res = heap_region_containing(addr);
2972 return res;
2973 }
2974
2975 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2976 Space* sp = space_containing(addr);
2977 if (sp != NULL) {
2978 return sp->block_start(addr);
2979 }
2980 return NULL;
2981 }
2982
2983 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2984 Space* sp = space_containing(addr);
2985 assert(sp != NULL, "block_size of address outside of heap");
2986 return sp->block_size(addr);
2987 }
2988
2989 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2990 Space* sp = space_containing(addr);
2991 return sp->block_is_obj(addr);
2992 }
2993
2994 bool G1CollectedHeap::supports_tlab_allocation() const {
2995 return true;
2996 }
2997
2998 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2999 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
3000 }
3001
3002 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3003 return young_list()->eden_used_bytes();
3004 }
3005
3006 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3007 // must be smaller than the humongous object limit.
3008 size_t G1CollectedHeap::max_tlab_size() const {
3009 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3010 }
3011
3012 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3013 // Return the remaining space in the cur alloc region, but not less than
3014 // the min TLAB size.
3015
3016 // Also, this value can be at most the humongous object threshold,
3017 // since we can't allow tlabs to grow big enough to accommodate
3018 // humongous objects.
3019
3020 HeapRegion* hr = _mutator_alloc_region.get();
3021 size_t max_tlab = max_tlab_size() * wordSize;
3022 if (hr == NULL) {
3023 return max_tlab;
3024 } else {
3025 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3026 }
3027 }
3028
3029 size_t G1CollectedHeap::max_capacity() const {
3030 return _g1_reserved.byte_size();
3031 }
3032
3033 jlong G1CollectedHeap::millis_since_last_gc() {
3034 // assert(false, "NYI");
3035 return 0;
3036 }
3037
3038 void G1CollectedHeap::prepare_for_verify() {
3039 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3040 ensure_parsability(false);
3041 }
3042 g1_rem_set()->prepare_for_verify();
3043 }
3044
3045 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3046 VerifyOption vo) {
3047 switch (vo) {
3048 case VerifyOption_G1UsePrevMarking:
3049 return hr->obj_allocated_since_prev_marking(obj);
3050 case VerifyOption_G1UseNextMarking:
3051 return hr->obj_allocated_since_next_marking(obj);
3052 case VerifyOption_G1UseMarkWord:
3053 return false;
3054 default:
3055 ShouldNotReachHere();
3056 }
3057 return false; // keep some compilers happy
3058 }
3059
3060 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3061 switch (vo) {
3062 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3063 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3064 case VerifyOption_G1UseMarkWord: return NULL;
3065 default: ShouldNotReachHere();
3066 }
3067 return NULL; // keep some compilers happy
3068 }
3069
3070 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3071 switch (vo) {
3072 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3073 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3074 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3075 default: ShouldNotReachHere();
3076 }
3077 return false; // keep some compilers happy
3078 }
3079
3080 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3081 switch (vo) {
3082 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3083 case VerifyOption_G1UseNextMarking: return "NTAMS";
3084 case VerifyOption_G1UseMarkWord: return "NONE";
3085 default: ShouldNotReachHere();
3086 }
3087 return NULL; // keep some compilers happy
3088 }
3089
3090 class VerifyRootsClosure: public OopClosure {
3091 private:
3092 G1CollectedHeap* _g1h;
3093 VerifyOption _vo;
3094 bool _failures;
3095 public:
3096 // _vo == UsePrevMarking -> use "prev" marking information,
3097 // _vo == UseNextMarking -> use "next" marking information,
3098 // _vo == UseMarkWord -> use mark word from object header.
3099 VerifyRootsClosure(VerifyOption vo) :
3100 _g1h(G1CollectedHeap::heap()),
3101 _vo(vo),
3102 _failures(false) { }
3103
3104 bool failures() { return _failures; }
3105
3106 template <class T> void do_oop_nv(T* p) {
3107 T heap_oop = oopDesc::load_heap_oop(p);
3108 if (!oopDesc::is_null(heap_oop)) {
3109 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3110 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3111 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3112 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3113 if (_vo == VerifyOption_G1UseMarkWord) {
3114 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3115 }
3116 obj->print_on(gclog_or_tty);
3117 _failures = true;
3118 }
3119 }
3120 }
3121
3122 void do_oop(oop* p) { do_oop_nv(p); }
3123 void do_oop(narrowOop* p) { do_oop_nv(p); }
3124 };
3125
3126 class G1VerifyCodeRootOopClosure: public OopClosure {
3127 G1CollectedHeap* _g1h;
3128 OopClosure* _root_cl;
3129 nmethod* _nm;
3130 VerifyOption _vo;
3131 bool _failures;
3132
3133 template <class T> void do_oop_work(T* p) {
3134 // First verify that this root is live
3135 _root_cl->do_oop(p);
3136
3137 if (!G1VerifyHeapRegionCodeRoots) {
3138 // We're not verifying the code roots attached to heap region.
3139 return;
3140 }
3141
3142 // Don't check the code roots during marking verification in a full GC
3143 if (_vo == VerifyOption_G1UseMarkWord) {
3144 return;
3145 }
3146
3147 // Now verify that the current nmethod (which contains p) is
3148 // in the code root list of the heap region containing the
3149 // object referenced by p.
3150
3151 T heap_oop = oopDesc::load_heap_oop(p);
3152 if (!oopDesc::is_null(heap_oop)) {
3153 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3154
3155 // Now fetch the region containing the object
3156 HeapRegion* hr = _g1h->heap_region_containing(obj);
3157 HeapRegionRemSet* hrrs = hr->rem_set();
3158 // Verify that the strong code root list for this region
3159 // contains the nmethod
3160 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3161 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3162 "from nmethod "PTR_FORMAT" not in strong "
3163 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3164 p, _nm, hr->bottom(), hr->end());
3165 _failures = true;
3166 }
3167 }
3168 }
3169
3170 public:
3171 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3172 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3173
3174 void do_oop(oop* p) { do_oop_work(p); }
3175 void do_oop(narrowOop* p) { do_oop_work(p); }
3176
3177 void set_nmethod(nmethod* nm) { _nm = nm; }
3178 bool failures() { return _failures; }
3179 };
3180
3181 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3182 G1VerifyCodeRootOopClosure* _oop_cl;
3183
3184 public:
3185 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3186 _oop_cl(oop_cl) {}
3187
3188 void do_code_blob(CodeBlob* cb) {
3189 nmethod* nm = cb->as_nmethod_or_null();
3190 if (nm != NULL) {
3191 _oop_cl->set_nmethod(nm);
3192 nm->oops_do(_oop_cl);
3193 }
3194 }
3195 };
3196
3197 class YoungRefCounterClosure : public OopClosure {
3198 G1CollectedHeap* _g1h;
3199 int _count;
3200 public:
3201 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3202 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3203 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3204
3205 int count() { return _count; }
3206 void reset_count() { _count = 0; };
3207 };
3208
3209 class VerifyKlassClosure: public KlassClosure {
3210 YoungRefCounterClosure _young_ref_counter_closure;
3211 OopClosure *_oop_closure;
3212 public:
3213 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3214 void do_klass(Klass* k) {
3215 k->oops_do(_oop_closure);
3216
3217 _young_ref_counter_closure.reset_count();
3218 k->oops_do(&_young_ref_counter_closure);
3219 if (_young_ref_counter_closure.count() > 0) {
3220 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3221 }
3222 }
3223 };
3224
3225 class VerifyLivenessOopClosure: public OopClosure {
3226 G1CollectedHeap* _g1h;
3227 VerifyOption _vo;
3228 public:
3229 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3230 _g1h(g1h), _vo(vo)
3231 { }
3232 void do_oop(narrowOop *p) { do_oop_work(p); }
3233 void do_oop( oop *p) { do_oop_work(p); }
3234
3235 template <class T> void do_oop_work(T *p) {
3236 oop obj = oopDesc::load_decode_heap_oop(p);
3237 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3238 "Dead object referenced by a not dead object");
3239 }
3240 };
3241
3242 class VerifyObjsInRegionClosure: public ObjectClosure {
3243 private:
3244 G1CollectedHeap* _g1h;
3245 size_t _live_bytes;
3246 HeapRegion *_hr;
3247 VerifyOption _vo;
3248 public:
3249 // _vo == UsePrevMarking -> use "prev" marking information,
3250 // _vo == UseNextMarking -> use "next" marking information,
3251 // _vo == UseMarkWord -> use mark word from object header.
3252 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3253 : _live_bytes(0), _hr(hr), _vo(vo) {
3254 _g1h = G1CollectedHeap::heap();
3255 }
3256 void do_object(oop o) {
3257 VerifyLivenessOopClosure isLive(_g1h, _vo);
3258 assert(o != NULL, "Huh?");
3259 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3260 // If the object is alive according to the mark word,
3261 // then verify that the marking information agrees.
3262 // Note we can't verify the contra-positive of the
3263 // above: if the object is dead (according to the mark
3264 // word), it may not be marked, or may have been marked
3265 // but has since became dead, or may have been allocated
3266 // since the last marking.
3267 if (_vo == VerifyOption_G1UseMarkWord) {
3268 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3269 }
3270
3271 o->oop_iterate_no_header(&isLive);
3272 if (!_hr->obj_allocated_since_prev_marking(o)) {
3273 size_t obj_size = o->size(); // Make sure we don't overflow
3274 _live_bytes += (obj_size * HeapWordSize);
3275 }
3276 }
3277 }
3278 size_t live_bytes() { return _live_bytes; }
3279 };
3280
3281 class PrintObjsInRegionClosure : public ObjectClosure {
3282 HeapRegion *_hr;
3283 G1CollectedHeap *_g1;
3284 public:
3285 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3286 _g1 = G1CollectedHeap::heap();
3287 };
3288
3289 void do_object(oop o) {
3290 if (o != NULL) {
3291 HeapWord *start = (HeapWord *) o;
3292 size_t word_sz = o->size();
3293 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3294 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3295 (void*) o, word_sz,
3296 _g1->isMarkedPrev(o),
3297 _g1->isMarkedNext(o),
3298 _hr->obj_allocated_since_prev_marking(o));
3299 HeapWord *end = start + word_sz;
3300 HeapWord *cur;
3301 int *val;
3302 for (cur = start; cur < end; cur++) {
3303 val = (int *) cur;
3304 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3305 }
3306 }
3307 }
3308 };
3309
3310 class VerifyRegionClosure: public HeapRegionClosure {
3311 private:
3312 bool _par;
3313 VerifyOption _vo;
3314 bool _failures;
3315 public:
3316 // _vo == UsePrevMarking -> use "prev" marking information,
3317 // _vo == UseNextMarking -> use "next" marking information,
3318 // _vo == UseMarkWord -> use mark word from object header.
3319 VerifyRegionClosure(bool par, VerifyOption vo)
3320 : _par(par),
3321 _vo(vo),
3322 _failures(false) {}
3323
3324 bool failures() {
3325 return _failures;
3326 }
3327
3328 bool doHeapRegion(HeapRegion* r) {
3329 if (!r->continuesHumongous()) {
3330 bool failures = false;
3331 r->verify(_vo, &failures);
3332 if (failures) {
3333 _failures = true;
3334 } else {
3335 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3336 r->object_iterate(¬_dead_yet_cl);
3337 if (_vo != VerifyOption_G1UseNextMarking) {
3338 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3339 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3340 "max_live_bytes "SIZE_FORMAT" "
3341 "< calculated "SIZE_FORMAT,
3342 r->bottom(), r->end(),
3343 r->max_live_bytes(),
3344 not_dead_yet_cl.live_bytes());
3345 _failures = true;
3346 }
3347 } else {
3348 // When vo == UseNextMarking we cannot currently do a sanity
3349 // check on the live bytes as the calculation has not been
3350 // finalized yet.
3351 }
3352 }
3353 }
3354 return false; // stop the region iteration if we hit a failure
3355 }
3356 };
3357
3358 // This is the task used for parallel verification of the heap regions
3359
3360 class G1ParVerifyTask: public AbstractGangTask {
3361 private:
3362 G1CollectedHeap* _g1h;
3363 VerifyOption _vo;
3364 bool _failures;
3365
3366 public:
3367 // _vo == UsePrevMarking -> use "prev" marking information,
3368 // _vo == UseNextMarking -> use "next" marking information,
3369 // _vo == UseMarkWord -> use mark word from object header.
3370 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3371 AbstractGangTask("Parallel verify task"),
3372 _g1h(g1h),
3373 _vo(vo),
3374 _failures(false) { }
3375
3376 bool failures() {
3377 return _failures;
3378 }
3379
3380 void work(uint worker_id) {
3381 HandleMark hm;
3382 VerifyRegionClosure blk(true, _vo);
3383 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3384 _g1h->workers()->active_workers(),
3385 HeapRegion::ParVerifyClaimValue);
3386 if (blk.failures()) {
3387 _failures = true;
3388 }
3389 }
3390 };
3391
3392 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3393 if (SafepointSynchronize::is_at_safepoint()) {
3394 assert(Thread::current()->is_VM_thread(),
3395 "Expected to be executed serially by the VM thread at this point");
3396
3397 if (!silent) { gclog_or_tty->print("Roots "); }
3398 VerifyRootsClosure rootsCl(vo);
3399 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3400 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3401 VerifyKlassClosure klassCl(this, &rootsCl);
3402
3403 // We apply the relevant closures to all the oops in the
3404 // system dictionary, the string table and the code cache.
3405 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3406
3407 // Need cleared claim bits for the strong roots processing
3408 ClassLoaderDataGraph::clear_claimed_marks();
3409
3410 process_strong_roots(true, // activate StrongRootsScope
3411 false, // we set "is scavenging" to false,
3412 // so we don't reset the dirty cards.
3413 ScanningOption(so), // roots scanning options
3414 &rootsCl,
3415 &blobsCl,
3416 &klassCl
3417 );
3418
3419 bool failures = rootsCl.failures() || codeRootsCl.failures();
3420
3421 if (vo != VerifyOption_G1UseMarkWord) {
3422 // If we're verifying during a full GC then the region sets
3423 // will have been torn down at the start of the GC. Therefore
3424 // verifying the region sets will fail. So we only verify
3425 // the region sets when not in a full GC.
3426 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3427 verify_region_sets();
3428 }
3429
3430 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3431 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3432 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3433 "sanity check");
3434
3435 G1ParVerifyTask task(this, vo);
3436 assert(UseDynamicNumberOfGCThreads ||
3437 workers()->active_workers() == workers()->total_workers(),
3438 "If not dynamic should be using all the workers");
3439 int n_workers = workers()->active_workers();
3440 set_par_threads(n_workers);
3441 workers()->run_task(&task);
3442 set_par_threads(0);
3443 if (task.failures()) {
3444 failures = true;
3445 }
3446
3447 // Checks that the expected amount of parallel work was done.
3448 // The implication is that n_workers is > 0.
3449 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3450 "sanity check");
3451
3452 reset_heap_region_claim_values();
3453
3454 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3455 "sanity check");
3456 } else {
3457 VerifyRegionClosure blk(false, vo);
3458 heap_region_iterate(&blk);
3459 if (blk.failures()) {
3460 failures = true;
3461 }
3462 }
3463 if (!silent) gclog_or_tty->print("RemSet ");
3464 rem_set()->verify();
3465
3466 if (G1StringDedup::is_enabled()) {
3467 if (!silent) gclog_or_tty->print("StrDedup ");
3468 G1StringDedup::verify();
3469 }
3470
3471 if (failures) {
3472 gclog_or_tty->print_cr("Heap:");
3473 // It helps to have the per-region information in the output to
3474 // help us track down what went wrong. This is why we call
3475 // print_extended_on() instead of print_on().
3476 print_extended_on(gclog_or_tty);
3477 gclog_or_tty->cr();
3478 #ifndef PRODUCT
3479 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3480 concurrent_mark()->print_reachable("at-verification-failure",
3481 vo, false /* all */);
3482 }
3483 #endif
3484 gclog_or_tty->flush();
3485 }
3486 guarantee(!failures, "there should not have been any failures");
3487 } else {
3488 if (!silent) {
3489 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3490 if (G1StringDedup::is_enabled()) {
3491 gclog_or_tty->print(", StrDedup");
3492 }
3493 gclog_or_tty->print(") ");
3494 }
3495 }
3496 }
3497
3498 void G1CollectedHeap::verify(bool silent) {
3499 verify(silent, VerifyOption_G1UsePrevMarking);
3500 }
3501
3502 double G1CollectedHeap::verify(bool guard, const char* msg) {
3503 double verify_time_ms = 0.0;
3504
3505 if (guard && total_collections() >= VerifyGCStartAt) {
3506 double verify_start = os::elapsedTime();
3507 HandleMark hm; // Discard invalid handles created during verification
3508 prepare_for_verify();
3509 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3510 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3511 }
3512
3513 return verify_time_ms;
3514 }
3515
3516 void G1CollectedHeap::verify_before_gc() {
3517 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3518 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3519 }
3520
3521 void G1CollectedHeap::verify_after_gc() {
3522 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3523 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3524 }
3525
3526 class PrintRegionClosure: public HeapRegionClosure {
3527 outputStream* _st;
3528 public:
3529 PrintRegionClosure(outputStream* st) : _st(st) {}
3530 bool doHeapRegion(HeapRegion* r) {
3531 r->print_on(_st);
3532 return false;
3533 }
3534 };
3535
3536 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3537 const HeapRegion* hr,
3538 const VerifyOption vo) const {
3539 switch (vo) {
3540 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3541 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3542 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3543 default: ShouldNotReachHere();
3544 }
3545 return false; // keep some compilers happy
3546 }
3547
3548 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3549 const VerifyOption vo) const {
3550 switch (vo) {
3551 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3552 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3553 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3554 default: ShouldNotReachHere();
3555 }
3556 return false; // keep some compilers happy
3557 }
3558
3559 void G1CollectedHeap::print_on(outputStream* st) const {
3560 st->print(" %-20s", "garbage-first heap");
3561 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3562 capacity()/K, used_unlocked()/K);
3563 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3564 _g1_storage.low_boundary(),
3565 _g1_storage.high(),
3566 _g1_storage.high_boundary());
3567 st->cr();
3568 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3569 uint young_regions = _young_list->length();
3570 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3571 (size_t) young_regions * HeapRegion::GrainBytes / K);
3572 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3573 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3574 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3575 st->cr();
3576 MetaspaceAux::print_on(st);
3577 }
3578
3579 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3580 print_on(st);
3581
3582 // Print the per-region information.
3583 st->cr();
3584 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3585 "HS=humongous(starts), HC=humongous(continues), "
3586 "CS=collection set, F=free, TS=gc time stamp, "
3587 "PTAMS=previous top-at-mark-start, "
3588 "NTAMS=next top-at-mark-start)");
3589 PrintRegionClosure blk(st);
3590 heap_region_iterate(&blk);
3591 }
3592
3593 void G1CollectedHeap::print_on_error(outputStream* st) const {
3594 this->CollectedHeap::print_on_error(st);
3595
3596 if (_cm != NULL) {
3597 st->cr();
3598 _cm->print_on_error(st);
3599 }
3600 }
3601
3602 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3603 if (G1CollectedHeap::use_parallel_gc_threads()) {
3604 workers()->print_worker_threads_on(st);
3605 }
3606 _cmThread->print_on(st);
3607 st->cr();
3608 _cm->print_worker_threads_on(st);
3609 _cg1r->print_worker_threads_on(st);
3610 if (G1StringDedup::is_enabled()) {
3611 G1StringDedup::print_worker_threads_on(st);
3612 }
3613 }
3614
3615 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3616 if (G1CollectedHeap::use_parallel_gc_threads()) {
3617 workers()->threads_do(tc);
3618 }
3619 tc->do_thread(_cmThread);
3620 _cg1r->threads_do(tc);
3621 if (G1StringDedup::is_enabled()) {
3622 G1StringDedup::threads_do(tc);
3623 }
3624 }
3625
3626 void G1CollectedHeap::print_tracing_info() const {
3627 // We'll overload this to mean "trace GC pause statistics."
3628 if (TraceGen0Time || TraceGen1Time) {
3629 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3630 // to that.
3631 g1_policy()->print_tracing_info();
3632 }
3633 if (G1SummarizeRSetStats) {
3634 g1_rem_set()->print_summary_info();
3635 }
3636 if (G1SummarizeConcMark) {
3637 concurrent_mark()->print_summary_info();
3638 }
3639 g1_policy()->print_yg_surv_rate_info();
3640 SpecializationStats::print();
3641 }
3642
3643 #ifndef PRODUCT
3644 // Helpful for debugging RSet issues.
3645
3646 class PrintRSetsClosure : public HeapRegionClosure {
3647 private:
3648 const char* _msg;
3649 size_t _occupied_sum;
3650
3651 public:
3652 bool doHeapRegion(HeapRegion* r) {
3653 HeapRegionRemSet* hrrs = r->rem_set();
3654 size_t occupied = hrrs->occupied();
3655 _occupied_sum += occupied;
3656
3657 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3658 HR_FORMAT_PARAMS(r));
3659 if (occupied == 0) {
3660 gclog_or_tty->print_cr(" RSet is empty");
3661 } else {
3662 hrrs->print();
3663 }
3664 gclog_or_tty->print_cr("----------");
3665 return false;
3666 }
3667
3668 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3669 gclog_or_tty->cr();
3670 gclog_or_tty->print_cr("========================================");
3671 gclog_or_tty->print_cr("%s", msg);
3672 gclog_or_tty->cr();
3673 }
3674
3675 ~PrintRSetsClosure() {
3676 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3677 gclog_or_tty->print_cr("========================================");
3678 gclog_or_tty->cr();
3679 }
3680 };
3681
3682 void G1CollectedHeap::print_cset_rsets() {
3683 PrintRSetsClosure cl("Printing CSet RSets");
3684 collection_set_iterate(&cl);
3685 }
3686
3687 void G1CollectedHeap::print_all_rsets() {
3688 PrintRSetsClosure cl("Printing All RSets");;
3689 heap_region_iterate(&cl);
3690 }
3691 #endif // PRODUCT
3692
3693 G1CollectedHeap* G1CollectedHeap::heap() {
3694 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3695 "not a garbage-first heap");
3696 return _g1h;
3697 }
3698
3699 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3700 // always_do_update_barrier = false;
3701 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3702 // Fill TLAB's and such
3703 accumulate_statistics_all_tlabs();
3704 ensure_parsability(true);
3705
3706 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3707 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3708 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3709 }
3710 }
3711
3712 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3713
3714 if (G1SummarizeRSetStats &&
3715 (G1SummarizeRSetStatsPeriod > 0) &&
3716 // we are at the end of the GC. Total collections has already been increased.
3717 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3718 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3719 }
3720
3721 // FIXME: what is this about?
3722 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3723 // is set.
3724 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3725 "derived pointer present"));
3726 // always_do_update_barrier = true;
3727
3728 resize_all_tlabs();
3729
3730 // We have just completed a GC. Update the soft reference
3731 // policy with the new heap occupancy
3732 Universe::update_heap_info_at_gc();
3733 }
3734
3735 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3736 unsigned int gc_count_before,
3737 bool* succeeded,
3738 GCCause::Cause gc_cause) {
3739 assert_heap_not_locked_and_not_at_safepoint();
3740 g1_policy()->record_stop_world_start();
3741 VM_G1IncCollectionPause op(gc_count_before,
3742 word_size,
3743 false, /* should_initiate_conc_mark */
3744 g1_policy()->max_pause_time_ms(),
3745 gc_cause);
3746 VMThread::execute(&op);
3747
3748 HeapWord* result = op.result();
3749 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3750 assert(result == NULL || ret_succeeded,
3751 "the result should be NULL if the VM did not succeed");
3752 *succeeded = ret_succeeded;
3753
3754 assert_heap_not_locked();
3755 return result;
3756 }
3757
3758 void
3759 G1CollectedHeap::doConcurrentMark() {
3760 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3761 if (!_cmThread->in_progress()) {
3762 _cmThread->set_started();
3763 CGC_lock->notify();
3764 }
3765 }
3766
3767 size_t G1CollectedHeap::pending_card_num() {
3768 size_t extra_cards = 0;
3769 JavaThread *curr = Threads::first();
3770 while (curr != NULL) {
3771 DirtyCardQueue& dcq = curr->dirty_card_queue();
3772 extra_cards += dcq.size();
3773 curr = curr->next();
3774 }
3775 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3776 size_t buffer_size = dcqs.buffer_size();
3777 size_t buffer_num = dcqs.completed_buffers_num();
3778
3779 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3780 // in bytes - not the number of 'entries'. We need to convert
3781 // into a number of cards.
3782 return (buffer_size * buffer_num + extra_cards) / oopSize;
3783 }
3784
3785 size_t G1CollectedHeap::cards_scanned() {
3786 return g1_rem_set()->cardsScanned();
3787 }
3788
3789 void
3790 G1CollectedHeap::setup_surviving_young_words() {
3791 assert(_surviving_young_words == NULL, "pre-condition");
3792 uint array_length = g1_policy()->young_cset_region_length();
3793 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3794 if (_surviving_young_words == NULL) {
3795 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3796 "Not enough space for young surv words summary.");
3797 }
3798 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3799 #ifdef ASSERT
3800 for (uint i = 0; i < array_length; ++i) {
3801 assert( _surviving_young_words[i] == 0, "memset above" );
3802 }
3803 #endif // !ASSERT
3804 }
3805
3806 void
3807 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3808 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3809 uint array_length = g1_policy()->young_cset_region_length();
3810 for (uint i = 0; i < array_length; ++i) {
3811 _surviving_young_words[i] += surv_young_words[i];
3812 }
3813 }
3814
3815 void
3816 G1CollectedHeap::cleanup_surviving_young_words() {
3817 guarantee( _surviving_young_words != NULL, "pre-condition" );
3818 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3819 _surviving_young_words = NULL;
3820 }
3821
3822 #ifdef ASSERT
3823 class VerifyCSetClosure: public HeapRegionClosure {
3824 public:
3825 bool doHeapRegion(HeapRegion* hr) {
3826 // Here we check that the CSet region's RSet is ready for parallel
3827 // iteration. The fields that we'll verify are only manipulated
3828 // when the region is part of a CSet and is collected. Afterwards,
3829 // we reset these fields when we clear the region's RSet (when the
3830 // region is freed) so they are ready when the region is
3831 // re-allocated. The only exception to this is if there's an
3832 // evacuation failure and instead of freeing the region we leave
3833 // it in the heap. In that case, we reset these fields during
3834 // evacuation failure handling.
3835 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3836
3837 // Here's a good place to add any other checks we'd like to
3838 // perform on CSet regions.
3839 return false;
3840 }
3841 };
3842 #endif // ASSERT
3843
3844 #if TASKQUEUE_STATS
3845 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3846 st->print_raw_cr("GC Task Stats");
3847 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3848 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3849 }
3850
3851 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3852 print_taskqueue_stats_hdr(st);
3853
3854 TaskQueueStats totals;
3855 const int n = workers() != NULL ? workers()->total_workers() : 1;
3856 for (int i = 0; i < n; ++i) {
3857 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3858 totals += task_queue(i)->stats;
3859 }
3860 st->print_raw("tot "); totals.print(st); st->cr();
3861
3862 DEBUG_ONLY(totals.verify());
3863 }
3864
3865 void G1CollectedHeap::reset_taskqueue_stats() {
3866 const int n = workers() != NULL ? workers()->total_workers() : 1;
3867 for (int i = 0; i < n; ++i) {
3868 task_queue(i)->stats.reset();
3869 }
3870 }
3871 #endif // TASKQUEUE_STATS
3872
3873 void G1CollectedHeap::log_gc_header() {
3874 if (!G1Log::fine()) {
3875 return;
3876 }
3877
3878 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3879
3880 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3881 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3882 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3883
3884 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3885 }
3886
3887 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3888 if (!G1Log::fine()) {
3889 return;
3890 }
3891
3892 if (G1Log::finer()) {
3893 if (evacuation_failed()) {
3894 gclog_or_tty->print(" (to-space exhausted)");
3895 }
3896 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3897 g1_policy()->phase_times()->note_gc_end();
3898 g1_policy()->phase_times()->print(pause_time_sec);
3899 g1_policy()->print_detailed_heap_transition();
3900 } else {
3901 if (evacuation_failed()) {
3902 gclog_or_tty->print("--");
3903 }
3904 g1_policy()->print_heap_transition();
3905 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3906 }
3907 gclog_or_tty->flush();
3908 }
3909
3910 bool
3911 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3912 assert_at_safepoint(true /* should_be_vm_thread */);
3913 guarantee(!is_gc_active(), "collection is not reentrant");
3914
3915 if (GC_locker::check_active_before_gc()) {
3916 return false;
3917 }
3918
3919 _gc_timer_stw->register_gc_start();
3920
3921 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3922
3923 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3924 ResourceMark rm;
3925
3926 print_heap_before_gc();
3927 trace_heap_before_gc(_gc_tracer_stw);
3928
3929 verify_region_sets_optional();
3930 verify_dirty_young_regions();
3931
3932 // This call will decide whether this pause is an initial-mark
3933 // pause. If it is, during_initial_mark_pause() will return true
3934 // for the duration of this pause.
3935 g1_policy()->decide_on_conc_mark_initiation();
3936
3937 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3938 assert(!g1_policy()->during_initial_mark_pause() ||
3939 g1_policy()->gcs_are_young(), "sanity");
3940
3941 // We also do not allow mixed GCs during marking.
3942 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3943
3944 // Record whether this pause is an initial mark. When the current
3945 // thread has completed its logging output and it's safe to signal
3946 // the CM thread, the flag's value in the policy has been reset.
3947 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3948
3949 // Inner scope for scope based logging, timers, and stats collection
3950 {
3951 EvacuationInfo evacuation_info;
3952
3953 if (g1_policy()->during_initial_mark_pause()) {
3954 // We are about to start a marking cycle, so we increment the
3955 // full collection counter.
3956 increment_old_marking_cycles_started();
3957 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3958 }
3959
3960 _gc_tracer_stw->report_yc_type(yc_type());
3961
3962 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3963
3964 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3965 workers()->active_workers() : 1);
3966 double pause_start_sec = os::elapsedTime();
3967 g1_policy()->phase_times()->note_gc_start(active_workers);
3968 log_gc_header();
3969
3970 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3971 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3972
3973 // If the secondary_free_list is not empty, append it to the
3974 // free_list. No need to wait for the cleanup operation to finish;
3975 // the region allocation code will check the secondary_free_list
3976 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3977 // set, skip this step so that the region allocation code has to
3978 // get entries from the secondary_free_list.
3979 if (!G1StressConcRegionFreeing) {
3980 append_secondary_free_list_if_not_empty_with_lock();
3981 }
3982
3983 assert(check_young_list_well_formed(), "young list should be well formed");
3984 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3985 "sanity check");
3986
3987 // Don't dynamically change the number of GC threads this early. A value of
3988 // 0 is used to indicate serial work. When parallel work is done,
3989 // it will be set.
3990
3991 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3992 IsGCActiveMark x;
3993
3994 gc_prologue(false);
3995 increment_total_collections(false /* full gc */);
3996 increment_gc_time_stamp();
3997
3998 verify_before_gc();
3999
4000 COMPILER2_PRESENT(DerivedPointerTable::clear());
4001
4002 // Please see comment in g1CollectedHeap.hpp and
4003 // G1CollectedHeap::ref_processing_init() to see how
4004 // reference processing currently works in G1.
4005
4006 // Enable discovery in the STW reference processor
4007 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4008 true /*verify_no_refs*/);
4009
4010 {
4011 // We want to temporarily turn off discovery by the
4012 // CM ref processor, if necessary, and turn it back on
4013 // on again later if we do. Using a scoped
4014 // NoRefDiscovery object will do this.
4015 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4016
4017 // Forget the current alloc region (we might even choose it to be part
4018 // of the collection set!).
4019 release_mutator_alloc_region();
4020
4021 // We should call this after we retire the mutator alloc
4022 // region(s) so that all the ALLOC / RETIRE events are generated
4023 // before the start GC event.
4024 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4025
4026 // This timing is only used by the ergonomics to handle our pause target.
4027 // It is unclear why this should not include the full pause. We will
4028 // investigate this in CR 7178365.
4029 //
4030 // Preserving the old comment here if that helps the investigation:
4031 //
4032 // The elapsed time induced by the start time below deliberately elides
4033 // the possible verification above.
4034 double sample_start_time_sec = os::elapsedTime();
4035
4036 #if YOUNG_LIST_VERBOSE
4037 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4038 _young_list->print();
4039 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4040 #endif // YOUNG_LIST_VERBOSE
4041
4042 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4043
4044 double scan_wait_start = os::elapsedTime();
4045 // We have to wait until the CM threads finish scanning the
4046 // root regions as it's the only way to ensure that all the
4047 // objects on them have been correctly scanned before we start
4048 // moving them during the GC.
4049 bool waited = _cm->root_regions()->wait_until_scan_finished();
4050 double wait_time_ms = 0.0;
4051 if (waited) {
4052 double scan_wait_end = os::elapsedTime();
4053 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4054 }
4055 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4056
4057 #if YOUNG_LIST_VERBOSE
4058 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4059 _young_list->print();
4060 #endif // YOUNG_LIST_VERBOSE
4061
4062 if (g1_policy()->during_initial_mark_pause()) {
4063 concurrent_mark()->checkpointRootsInitialPre();
4064 }
4065
4066 #if YOUNG_LIST_VERBOSE
4067 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4068 _young_list->print();
4069 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4070 #endif // YOUNG_LIST_VERBOSE
4071
4072 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4073
4074 _cm->note_start_of_gc();
4075 // We should not verify the per-thread SATB buffers given that
4076 // we have not filtered them yet (we'll do so during the
4077 // GC). We also call this after finalize_cset() to
4078 // ensure that the CSet has been finalized.
4079 _cm->verify_no_cset_oops(true /* verify_stacks */,
4080 true /* verify_enqueued_buffers */,
4081 false /* verify_thread_buffers */,
4082 true /* verify_fingers */);
4083
4084 if (_hr_printer.is_active()) {
4085 HeapRegion* hr = g1_policy()->collection_set();
4086 while (hr != NULL) {
4087 G1HRPrinter::RegionType type;
4088 if (!hr->is_young()) {
4089 type = G1HRPrinter::Old;
4090 } else if (hr->is_survivor()) {
4091 type = G1HRPrinter::Survivor;
4092 } else {
4093 type = G1HRPrinter::Eden;
4094 }
4095 _hr_printer.cset(hr);
4096 hr = hr->next_in_collection_set();
4097 }
4098 }
4099
4100 #ifdef ASSERT
4101 VerifyCSetClosure cl;
4102 collection_set_iterate(&cl);
4103 #endif // ASSERT
4104
4105 setup_surviving_young_words();
4106
4107 // Initialize the GC alloc regions.
4108 init_gc_alloc_regions(evacuation_info);
4109
4110 // Actually do the work...
4111 evacuate_collection_set(evacuation_info);
4112
4113 // We do this to mainly verify the per-thread SATB buffers
4114 // (which have been filtered by now) since we didn't verify
4115 // them earlier. No point in re-checking the stacks / enqueued
4116 // buffers given that the CSet has not changed since last time
4117 // we checked.
4118 _cm->verify_no_cset_oops(false /* verify_stacks */,
4119 false /* verify_enqueued_buffers */,
4120 true /* verify_thread_buffers */,
4121 true /* verify_fingers */);
4122
4123 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4124 g1_policy()->clear_collection_set();
4125
4126 cleanup_surviving_young_words();
4127
4128 // Start a new incremental collection set for the next pause.
4129 g1_policy()->start_incremental_cset_building();
4130
4131 clear_cset_fast_test();
4132
4133 _young_list->reset_sampled_info();
4134
4135 // Don't check the whole heap at this point as the
4136 // GC alloc regions from this pause have been tagged
4137 // as survivors and moved on to the survivor list.
4138 // Survivor regions will fail the !is_young() check.
4139 assert(check_young_list_empty(false /* check_heap */),
4140 "young list should be empty");
4141
4142 #if YOUNG_LIST_VERBOSE
4143 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4144 _young_list->print();
4145 #endif // YOUNG_LIST_VERBOSE
4146
4147 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4148 _young_list->first_survivor_region(),
4149 _young_list->last_survivor_region());
4150
4151 _young_list->reset_auxilary_lists();
4152
4153 if (evacuation_failed()) {
4154 _summary_bytes_used = recalculate_used();
4155 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4156 for (uint i = 0; i < n_queues; i++) {
4157 if (_evacuation_failed_info_array[i].has_failed()) {
4158 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4159 }
4160 }
4161 } else {
4162 // The "used" of the the collection set have already been subtracted
4163 // when they were freed. Add in the bytes evacuated.
4164 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4165 }
4166
4167 if (g1_policy()->during_initial_mark_pause()) {
4168 // We have to do this before we notify the CM threads that
4169 // they can start working to make sure that all the
4170 // appropriate initialization is done on the CM object.
4171 concurrent_mark()->checkpointRootsInitialPost();
4172 set_marking_started();
4173 // Note that we don't actually trigger the CM thread at
4174 // this point. We do that later when we're sure that
4175 // the current thread has completed its logging output.
4176 }
4177
4178 allocate_dummy_regions();
4179
4180 #if YOUNG_LIST_VERBOSE
4181 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4182 _young_list->print();
4183 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4184 #endif // YOUNG_LIST_VERBOSE
4185
4186 init_mutator_alloc_region();
4187
4188 {
4189 size_t expand_bytes = g1_policy()->expansion_amount();
4190 if (expand_bytes > 0) {
4191 size_t bytes_before = capacity();
4192 // No need for an ergo verbose message here,
4193 // expansion_amount() does this when it returns a value > 0.
4194 if (!expand(expand_bytes)) {
4195 // We failed to expand the heap so let's verify that
4196 // committed/uncommitted amount match the backing store
4197 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4198 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4199 }
4200 }
4201 }
4202
4203 // We redo the verification but now wrt to the new CSet which
4204 // has just got initialized after the previous CSet was freed.
4205 _cm->verify_no_cset_oops(true /* verify_stacks */,
4206 true /* verify_enqueued_buffers */,
4207 true /* verify_thread_buffers */,
4208 true /* verify_fingers */);
4209 _cm->note_end_of_gc();
4210
4211 // This timing is only used by the ergonomics to handle our pause target.
4212 // It is unclear why this should not include the full pause. We will
4213 // investigate this in CR 7178365.
4214 double sample_end_time_sec = os::elapsedTime();
4215 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4216 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4217
4218 MemoryService::track_memory_usage();
4219
4220 // In prepare_for_verify() below we'll need to scan the deferred
4221 // update buffers to bring the RSets up-to-date if
4222 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4223 // the update buffers we'll probably need to scan cards on the
4224 // regions we just allocated to (i.e., the GC alloc
4225 // regions). However, during the last GC we called
4226 // set_saved_mark() on all the GC alloc regions, so card
4227 // scanning might skip the [saved_mark_word()...top()] area of
4228 // those regions (i.e., the area we allocated objects into
4229 // during the last GC). But it shouldn't. Given that
4230 // saved_mark_word() is conditional on whether the GC time stamp
4231 // on the region is current or not, by incrementing the GC time
4232 // stamp here we invalidate all the GC time stamps on all the
4233 // regions and saved_mark_word() will simply return top() for
4234 // all the regions. This is a nicer way of ensuring this rather
4235 // than iterating over the regions and fixing them. In fact, the
4236 // GC time stamp increment here also ensures that
4237 // saved_mark_word() will return top() between pauses, i.e.,
4238 // during concurrent refinement. So we don't need the
4239 // is_gc_active() check to decided which top to use when
4240 // scanning cards (see CR 7039627).
4241 increment_gc_time_stamp();
4242
4243 verify_after_gc();
4244
4245 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4246 ref_processor_stw()->verify_no_references_recorded();
4247
4248 // CM reference discovery will be re-enabled if necessary.
4249 }
4250
4251 // We should do this after we potentially expand the heap so
4252 // that all the COMMIT events are generated before the end GC
4253 // event, and after we retire the GC alloc regions so that all
4254 // RETIRE events are generated before the end GC event.
4255 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4256
4257 if (mark_in_progress()) {
4258 concurrent_mark()->update_g1_committed();
4259 }
4260
4261 #ifdef TRACESPINNING
4262 ParallelTaskTerminator::print_termination_counts();
4263 #endif
4264
4265 gc_epilogue(false);
4266 }
4267
4268 // Print the remainder of the GC log output.
4269 log_gc_footer(os::elapsedTime() - pause_start_sec);
4270
4271 // It is not yet to safe to tell the concurrent mark to
4272 // start as we have some optional output below. We don't want the
4273 // output from the concurrent mark thread interfering with this
4274 // logging output either.
4275
4276 _hrs.verify_optional();
4277 verify_region_sets_optional();
4278
4279 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4280 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4281
4282 print_heap_after_gc();
4283 trace_heap_after_gc(_gc_tracer_stw);
4284
4285 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4286 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4287 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4288 // before any GC notifications are raised.
4289 g1mm()->update_sizes();
4290
4291 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4292 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4293 _gc_timer_stw->register_gc_end();
4294 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4295 }
4296 // It should now be safe to tell the concurrent mark thread to start
4297 // without its logging output interfering with the logging output
4298 // that came from the pause.
4299
4300 if (should_start_conc_mark) {
4301 // CAUTION: after the doConcurrentMark() call below,
4302 // the concurrent marking thread(s) could be running
4303 // concurrently with us. Make sure that anything after
4304 // this point does not assume that we are the only GC thread
4305 // running. Note: of course, the actual marking work will
4306 // not start until the safepoint itself is released in
4307 // SuspendibleThreadSet::desynchronize().
4308 doConcurrentMark();
4309 }
4310
4311 return true;
4312 }
4313
4314 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4315 {
4316 size_t gclab_word_size;
4317 switch (purpose) {
4318 case GCAllocForSurvived:
4319 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4320 break;
4321 case GCAllocForTenured:
4322 gclab_word_size = _old_plab_stats.desired_plab_sz();
4323 break;
4324 default:
4325 assert(false, "unknown GCAllocPurpose");
4326 gclab_word_size = _old_plab_stats.desired_plab_sz();
4327 break;
4328 }
4329
4330 // Prevent humongous PLAB sizes for two reasons:
4331 // * PLABs are allocated using a similar paths as oops, but should
4332 // never be in a humongous region
4333 // * Allowing humongous PLABs needlessly churns the region free lists
4334 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4335 }
4336
4337 void G1CollectedHeap::init_mutator_alloc_region() {
4338 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4339 _mutator_alloc_region.init();
4340 }
4341
4342 void G1CollectedHeap::release_mutator_alloc_region() {
4343 _mutator_alloc_region.release();
4344 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4345 }
4346
4347 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4348 assert_at_safepoint(true /* should_be_vm_thread */);
4349
4350 _survivor_gc_alloc_region.init();
4351 _old_gc_alloc_region.init();
4352 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4353 _retained_old_gc_alloc_region = NULL;
4354
4355 // We will discard the current GC alloc region if:
4356 // a) it's in the collection set (it can happen!),
4357 // b) it's already full (no point in using it),
4358 // c) it's empty (this means that it was emptied during
4359 // a cleanup and it should be on the free list now), or
4360 // d) it's humongous (this means that it was emptied
4361 // during a cleanup and was added to the free list, but
4362 // has been subsequently used to allocate a humongous
4363 // object that may be less than the region size).
4364 if (retained_region != NULL &&
4365 !retained_region->in_collection_set() &&
4366 !(retained_region->top() == retained_region->end()) &&
4367 !retained_region->is_empty() &&
4368 !retained_region->isHumongous()) {
4369 retained_region->set_saved_mark();
4370 // The retained region was added to the old region set when it was
4371 // retired. We have to remove it now, since we don't allow regions
4372 // we allocate to in the region sets. We'll re-add it later, when
4373 // it's retired again.
4374 _old_set.remove(retained_region);
4375 bool during_im = g1_policy()->during_initial_mark_pause();
4376 retained_region->note_start_of_copying(during_im);
4377 _old_gc_alloc_region.set(retained_region);
4378 _hr_printer.reuse(retained_region);
4379 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4380 }
4381 }
4382
4383 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4384 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4385 _old_gc_alloc_region.count());
4386 _survivor_gc_alloc_region.release();
4387 // If we have an old GC alloc region to release, we'll save it in
4388 // _retained_old_gc_alloc_region. If we don't
4389 // _retained_old_gc_alloc_region will become NULL. This is what we
4390 // want either way so no reason to check explicitly for either
4391 // condition.
4392 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4393
4394 if (ResizePLAB) {
4395 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4396 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4397 }
4398 }
4399
4400 void G1CollectedHeap::abandon_gc_alloc_regions() {
4401 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4402 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4403 _retained_old_gc_alloc_region = NULL;
4404 }
4405
4406 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4407 _drain_in_progress = false;
4408 set_evac_failure_closure(cl);
4409 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4410 }
4411
4412 void G1CollectedHeap::finalize_for_evac_failure() {
4413 assert(_evac_failure_scan_stack != NULL &&
4414 _evac_failure_scan_stack->length() == 0,
4415 "Postcondition");
4416 assert(!_drain_in_progress, "Postcondition");
4417 delete _evac_failure_scan_stack;
4418 _evac_failure_scan_stack = NULL;
4419 }
4420
4421 void G1CollectedHeap::remove_self_forwarding_pointers() {
4422 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4423
4424 double remove_self_forwards_start = os::elapsedTime();
4425
4426 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4427
4428 if (G1CollectedHeap::use_parallel_gc_threads()) {
4429 set_par_threads();
4430 workers()->run_task(&rsfp_task);
4431 set_par_threads(0);
4432 } else {
4433 rsfp_task.work(0);
4434 }
4435
4436 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4437
4438 // Reset the claim values in the regions in the collection set.
4439 reset_cset_heap_region_claim_values();
4440
4441 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4442
4443 // Now restore saved marks, if any.
4444 assert(_objs_with_preserved_marks.size() ==
4445 _preserved_marks_of_objs.size(), "Both or none.");
4446 while (!_objs_with_preserved_marks.is_empty()) {
4447 oop obj = _objs_with_preserved_marks.pop();
4448 markOop m = _preserved_marks_of_objs.pop();
4449 obj->set_mark(m);
4450 }
4451 _objs_with_preserved_marks.clear(true);
4452 _preserved_marks_of_objs.clear(true);
4453
4454 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4455 }
4456
4457 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4458 _evac_failure_scan_stack->push(obj);
4459 }
4460
4461 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4462 assert(_evac_failure_scan_stack != NULL, "precondition");
4463
4464 while (_evac_failure_scan_stack->length() > 0) {
4465 oop obj = _evac_failure_scan_stack->pop();
4466 _evac_failure_closure->set_region(heap_region_containing(obj));
4467 obj->oop_iterate_backwards(_evac_failure_closure);
4468 }
4469 }
4470
4471 oop
4472 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4473 oop old) {
4474 assert(obj_in_cs(old),
4475 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4476 (HeapWord*) old));
4477 markOop m = old->mark();
4478 oop forward_ptr = old->forward_to_atomic(old);
4479 if (forward_ptr == NULL) {
4480 // Forward-to-self succeeded.
4481 assert(_par_scan_state != NULL, "par scan state");
4482 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4483 uint queue_num = _par_scan_state->queue_num();
4484
4485 _evacuation_failed = true;
4486 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4487 if (_evac_failure_closure != cl) {
4488 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4489 assert(!_drain_in_progress,
4490 "Should only be true while someone holds the lock.");
4491 // Set the global evac-failure closure to the current thread's.
4492 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4493 set_evac_failure_closure(cl);
4494 // Now do the common part.
4495 handle_evacuation_failure_common(old, m);
4496 // Reset to NULL.
4497 set_evac_failure_closure(NULL);
4498 } else {
4499 // The lock is already held, and this is recursive.
4500 assert(_drain_in_progress, "This should only be the recursive case.");
4501 handle_evacuation_failure_common(old, m);
4502 }
4503 return old;
4504 } else {
4505 // Forward-to-self failed. Either someone else managed to allocate
4506 // space for this object (old != forward_ptr) or they beat us in
4507 // self-forwarding it (old == forward_ptr).
4508 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4509 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4510 "should not be in the CSet",
4511 (HeapWord*) old, (HeapWord*) forward_ptr));
4512 return forward_ptr;
4513 }
4514 }
4515
4516 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4517 preserve_mark_if_necessary(old, m);
4518
4519 HeapRegion* r = heap_region_containing(old);
4520 if (!r->evacuation_failed()) {
4521 r->set_evacuation_failed(true);
4522 _hr_printer.evac_failure(r);
4523 }
4524
4525 push_on_evac_failure_scan_stack(old);
4526
4527 if (!_drain_in_progress) {
4528 // prevent recursion in copy_to_survivor_space()
4529 _drain_in_progress = true;
4530 drain_evac_failure_scan_stack();
4531 _drain_in_progress = false;
4532 }
4533 }
4534
4535 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4536 assert(evacuation_failed(), "Oversaving!");
4537 // We want to call the "for_promotion_failure" version only in the
4538 // case of a promotion failure.
4539 if (m->must_be_preserved_for_promotion_failure(obj)) {
4540 _objs_with_preserved_marks.push(obj);
4541 _preserved_marks_of_objs.push(m);
4542 }
4543 }
4544
4545 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4546 size_t word_size) {
4547 if (purpose == GCAllocForSurvived) {
4548 HeapWord* result = survivor_attempt_allocation(word_size);
4549 if (result != NULL) {
4550 return result;
4551 } else {
4552 // Let's try to allocate in the old gen in case we can fit the
4553 // object there.
4554 return old_attempt_allocation(word_size);
4555 }
4556 } else {
4557 assert(purpose == GCAllocForTenured, "sanity");
4558 HeapWord* result = old_attempt_allocation(word_size);
4559 if (result != NULL) {
4560 return result;
4561 } else {
4562 // Let's try to allocate in the survivors in case we can fit the
4563 // object there.
4564 return survivor_attempt_allocation(word_size);
4565 }
4566 }
4567
4568 ShouldNotReachHere();
4569 // Trying to keep some compilers happy.
4570 return NULL;
4571 }
4572
4573 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4574 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4575
4576 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4577 : _g1h(g1h),
4578 _refs(g1h->task_queue(queue_num)),
4579 _dcq(&g1h->dirty_card_queue_set()),
4580 _ct_bs(g1h->g1_barrier_set()),
4581 _g1_rem(g1h->g1_rem_set()),
4582 _hash_seed(17), _queue_num(queue_num),
4583 _term_attempts(0),
4584 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4585 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4586 _age_table(false), _scanner(g1h, this, rp),
4587 _strong_roots_time(0), _term_time(0),
4588 _alloc_buffer_waste(0), _undo_waste(0) {
4589 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4590 // we "sacrifice" entry 0 to keep track of surviving bytes for
4591 // non-young regions (where the age is -1)
4592 // We also add a few elements at the beginning and at the end in
4593 // an attempt to eliminate cache contention
4594 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4595 uint array_length = PADDING_ELEM_NUM +
4596 real_length +
4597 PADDING_ELEM_NUM;
4598 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4599 if (_surviving_young_words_base == NULL)
4600 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4601 "Not enough space for young surv histo.");
4602 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4603 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4604
4605 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4606 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4607
4608 _start = os::elapsedTime();
4609 }
4610
4611 void
4612 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4613 {
4614 st->print_raw_cr("GC Termination Stats");
4615 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4616 " ------waste (KiB)------");
4617 st->print_raw_cr("thr ms ms % ms % attempts"
4618 " total alloc undo");
4619 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4620 " ------- ------- -------");
4621 }
4622
4623 void
4624 G1ParScanThreadState::print_termination_stats(int i,
4625 outputStream* const st) const
4626 {
4627 const double elapsed_ms = elapsed_time() * 1000.0;
4628 const double s_roots_ms = strong_roots_time() * 1000.0;
4629 const double term_ms = term_time() * 1000.0;
4630 st->print_cr("%3d %9.2f %9.2f %6.2f "
4631 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4632 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4633 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4634 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4635 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4636 alloc_buffer_waste() * HeapWordSize / K,
4637 undo_waste() * HeapWordSize / K);
4638 }
4639
4640 #ifdef ASSERT
4641 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4642 assert(ref != NULL, "invariant");
4643 assert(UseCompressedOops, "sanity");
4644 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4645 oop p = oopDesc::load_decode_heap_oop(ref);
4646 assert(_g1h->is_in_g1_reserved(p),
4647 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4648 return true;
4649 }
4650
4651 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4652 assert(ref != NULL, "invariant");
4653 if (has_partial_array_mask(ref)) {
4654 // Must be in the collection set--it's already been copied.
4655 oop p = clear_partial_array_mask(ref);
4656 assert(_g1h->obj_in_cs(p),
4657 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4658 } else {
4659 oop p = oopDesc::load_decode_heap_oop(ref);
4660 assert(_g1h->is_in_g1_reserved(p),
4661 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4662 }
4663 return true;
4664 }
4665
4666 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4667 if (ref.is_narrow()) {
4668 return verify_ref((narrowOop*) ref);
4669 } else {
4670 return verify_ref((oop*) ref);
4671 }
4672 }
4673 #endif // ASSERT
4674
4675 void G1ParScanThreadState::trim_queue() {
4676 assert(_evac_failure_cl != NULL, "not set");
4677
4678 StarTask ref;
4679 do {
4680 // Drain the overflow stack first, so other threads can steal.
4681 while (refs()->pop_overflow(ref)) {
4682 deal_with_reference(ref);
4683 }
4684
4685 while (refs()->pop_local(ref)) {
4686 deal_with_reference(ref);
4687 }
4688 } while (!refs()->is_empty());
4689 }
4690
4691 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4692 G1ParScanThreadState* par_scan_state) :
4693 _g1(g1), _par_scan_state(par_scan_state),
4694 _worker_id(par_scan_state->queue_num()) { }
4695
4696 void G1ParCopyHelper::mark_object(oop obj) {
4697 #ifdef ASSERT
4698 HeapRegion* hr = _g1->heap_region_containing(obj);
4699 assert(hr != NULL, "sanity");
4700 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4701 #endif // ASSERT
4702
4703 // We know that the object is not moving so it's safe to read its size.
4704 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4705 }
4706
4707 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4708 #ifdef ASSERT
4709 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4710 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4711 assert(from_obj != to_obj, "should not be self-forwarded");
4712
4713 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4714 assert(from_hr != NULL, "sanity");
4715 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4716
4717 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4718 assert(to_hr != NULL, "sanity");
4719 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4720 #endif // ASSERT
4721
4722 // The object might be in the process of being copied by another
4723 // worker so we cannot trust that its to-space image is
4724 // well-formed. So we have to read its size from its from-space
4725 // image which we know should not be changing.
4726 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4727 }
4728
4729 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4730 size_t word_sz = old->size();
4731 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4732 // +1 to make the -1 indexes valid...
4733 int young_index = from_region->young_index_in_cset()+1;
4734 assert( (from_region->is_young() && young_index > 0) ||
4735 (!from_region->is_young() && young_index == 0), "invariant" );
4736 G1CollectorPolicy* g1p = _g1h->g1_policy();
4737 markOop m = old->mark();
4738 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4739 : m->age();
4740 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4741 word_sz);
4742 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4743 #ifndef PRODUCT
4744 // Should this evacuation fail?
4745 if (_g1h->evacuation_should_fail()) {
4746 if (obj_ptr != NULL) {
4747 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4748 obj_ptr = NULL;
4749 }
4750 }
4751 #endif // !PRODUCT
4752
4753 if (obj_ptr == NULL) {
4754 // This will either forward-to-self, or detect that someone else has
4755 // installed a forwarding pointer.
4756 return _g1h->handle_evacuation_failure_par(this, old);
4757 }
4758
4759 oop obj = oop(obj_ptr);
4760
4761 // We're going to allocate linearly, so might as well prefetch ahead.
4762 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4763
4764 oop forward_ptr = old->forward_to_atomic(obj);
4765 if (forward_ptr == NULL) {
4766 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4767
4768 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4769 // we actually allocated from and update alloc_purpose accordingly
4770 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4771 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4772
4773 if (g1p->track_object_age(alloc_purpose)) {
4774 // We could simply do obj->incr_age(). However, this causes a
4775 // performance issue. obj->incr_age() will first check whether
4776 // the object has a displaced mark by checking its mark word;
4777 // getting the mark word from the new location of the object
4778 // stalls. So, given that we already have the mark word and we
4779 // are about to install it anyway, it's better to increase the
4780 // age on the mark word, when the object does not have a
4781 // displaced mark word. We're not expecting many objects to have
4782 // a displaced marked word, so that case is not optimized
4783 // further (it could be...) and we simply call obj->incr_age().
4784
4785 if (m->has_displaced_mark_helper()) {
4786 // in this case, we have to install the mark word first,
4787 // otherwise obj looks to be forwarded (the old mark word,
4788 // which contains the forward pointer, was copied)
4789 obj->set_mark(m);
4790 obj->incr_age();
4791 } else {
4792 m = m->incr_age();
4793 obj->set_mark(m);
4794 }
4795 age_table()->add(obj, word_sz);
4796 } else {
4797 obj->set_mark(m);
4798 }
4799
4800 if (G1StringDedup::is_enabled()) {
4801 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4802 to_region->is_young(),
4803 queue_num(),
4804 obj);
4805 }
4806
4807 size_t* surv_young_words = surviving_young_words();
4808 surv_young_words[young_index] += word_sz;
4809
4810 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4811 // We keep track of the next start index in the length field of
4812 // the to-space object. The actual length can be found in the
4813 // length field of the from-space object.
4814 arrayOop(obj)->set_length(0);
4815 oop* old_p = set_partial_array_mask(old);
4816 push_on_queue(old_p);
4817 } else {
4818 // No point in using the slower heap_region_containing() method,
4819 // given that we know obj is in the heap.
4820 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4821 obj->oop_iterate_backwards(&_scanner);
4822 }
4823 } else {
4824 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4825 obj = forward_ptr;
4826 }
4827 return obj;
4828 }
4829
4830 template <class T>
4831 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4832 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4833 _scanned_klass->record_modified_oops();
4834 }
4835 }
4836
4837 template <G1Barrier barrier, bool do_mark_object>
4838 template <class T>
4839 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4840 T heap_oop = oopDesc::load_heap_oop(p);
4841
4842 if (oopDesc::is_null(heap_oop)) {
4843 return;
4844 }
4845
4846 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4847
4848 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4849
4850 if (_g1->in_cset_fast_test(obj)) {
4851 oop forwardee;
4852 if (obj->is_forwarded()) {
4853 forwardee = obj->forwardee();
4854 } else {
4855 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4856 }
4857 assert(forwardee != NULL, "forwardee should not be NULL");
4858 oopDesc::encode_store_heap_oop(p, forwardee);
4859 if (do_mark_object && forwardee != obj) {
4860 // If the object is self-forwarded we don't need to explicitly
4861 // mark it, the evacuation failure protocol will do so.
4862 mark_forwarded_object(obj, forwardee);
4863 }
4864
4865 if (barrier == G1BarrierKlass) {
4866 do_klass_barrier(p, forwardee);
4867 }
4868 } else {
4869 // The object is not in collection set. If we're a root scanning
4870 // closure during an initial mark pause (i.e. do_mark_object will
4871 // be true) then attempt to mark the object.
4872 if (do_mark_object) {
4873 mark_object(obj);
4874 }
4875 }
4876
4877 if (barrier == G1BarrierEvac) {
4878 _par_scan_state->update_rs(_from, p, _worker_id);
4879 }
4880 }
4881
4882 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4883 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4884
4885 class G1ParEvacuateFollowersClosure : public VoidClosure {
4886 protected:
4887 G1CollectedHeap* _g1h;
4888 G1ParScanThreadState* _par_scan_state;
4889 RefToScanQueueSet* _queues;
4890 ParallelTaskTerminator* _terminator;
4891
4892 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4893 RefToScanQueueSet* queues() { return _queues; }
4894 ParallelTaskTerminator* terminator() { return _terminator; }
4895
4896 public:
4897 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4898 G1ParScanThreadState* par_scan_state,
4899 RefToScanQueueSet* queues,
4900 ParallelTaskTerminator* terminator)
4901 : _g1h(g1h), _par_scan_state(par_scan_state),
4902 _queues(queues), _terminator(terminator) {}
4903
4904 void do_void();
4905
4906 private:
4907 inline bool offer_termination();
4908 };
4909
4910 bool G1ParEvacuateFollowersClosure::offer_termination() {
4911 G1ParScanThreadState* const pss = par_scan_state();
4912 pss->start_term_time();
4913 const bool res = terminator()->offer_termination();
4914 pss->end_term_time();
4915 return res;
4916 }
4917
4918 void G1ParEvacuateFollowersClosure::do_void() {
4919 StarTask stolen_task;
4920 G1ParScanThreadState* const pss = par_scan_state();
4921 pss->trim_queue();
4922
4923 do {
4924 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4925 assert(pss->verify_task(stolen_task), "sanity");
4926 if (stolen_task.is_narrow()) {
4927 pss->deal_with_reference((narrowOop*) stolen_task);
4928 } else {
4929 pss->deal_with_reference((oop*) stolen_task);
4930 }
4931
4932 // We've just processed a reference and we might have made
4933 // available new entries on the queues. So we have to make sure
4934 // we drain the queues as necessary.
4935 pss->trim_queue();
4936 }
4937 } while (!offer_termination());
4938
4939 pss->retire_alloc_buffers();
4940 }
4941
4942 class G1KlassScanClosure : public KlassClosure {
4943 G1ParCopyHelper* _closure;
4944 bool _process_only_dirty;
4945 int _count;
4946 public:
4947 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4948 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4949 void do_klass(Klass* klass) {
4950 // If the klass has not been dirtied we know that there's
4951 // no references into the young gen and we can skip it.
4952 if (!_process_only_dirty || klass->has_modified_oops()) {
4953 // Clean the klass since we're going to scavenge all the metadata.
4954 klass->clear_modified_oops();
4955
4956 // Tell the closure that this klass is the Klass to scavenge
4957 // and is the one to dirty if oops are left pointing into the young gen.
4958 _closure->set_scanned_klass(klass);
4959
4960 klass->oops_do(_closure);
4961
4962 _closure->set_scanned_klass(NULL);
4963 }
4964 _count++;
4965 }
4966 };
4967
4968 class G1ParTask : public AbstractGangTask {
4969 protected:
4970 G1CollectedHeap* _g1h;
4971 RefToScanQueueSet *_queues;
4972 ParallelTaskTerminator _terminator;
4973 uint _n_workers;
4974
4975 Mutex _stats_lock;
4976 Mutex* stats_lock() { return &_stats_lock; }
4977
4978 size_t getNCards() {
4979 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4980 / G1BlockOffsetSharedArray::N_bytes;
4981 }
4982
4983 public:
4984 G1ParTask(G1CollectedHeap* g1h,
4985 RefToScanQueueSet *task_queues)
4986 : AbstractGangTask("G1 collection"),
4987 _g1h(g1h),
4988 _queues(task_queues),
4989 _terminator(0, _queues),
4990 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4991 {}
4992
4993 RefToScanQueueSet* queues() { return _queues; }
4994
4995 RefToScanQueue *work_queue(int i) {
4996 return queues()->queue(i);
4997 }
4998
4999 ParallelTaskTerminator* terminator() { return &_terminator; }
5000
5001 virtual void set_for_termination(int active_workers) {
5002 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5003 // in the young space (_par_seq_tasks) in the G1 heap
5004 // for SequentialSubTasksDone.
5005 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5006 // both of which need setting by set_n_termination().
5007 _g1h->SharedHeap::set_n_termination(active_workers);
5008 _g1h->set_n_termination(active_workers);
5009 terminator()->reset_for_reuse(active_workers);
5010 _n_workers = active_workers;
5011 }
5012
5013 void work(uint worker_id) {
5014 if (worker_id >= _n_workers) return; // no work needed this round
5015
5016 double start_time_ms = os::elapsedTime() * 1000.0;
5017 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5018
5019 {
5020 ResourceMark rm;
5021 HandleMark hm;
5022
5023 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5024
5025 G1ParScanThreadState pss(_g1h, worker_id, rp);
5026 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5027
5028 pss.set_evac_failure_closure(&evac_failure_cl);
5029
5030 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5031 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5032
5033 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5034 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5035
5036 bool only_young = _g1h->g1_policy()->gcs_are_young();
5037 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5038 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5039
5040 OopClosure* scan_root_cl = &only_scan_root_cl;
5041 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5042
5043 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5044 // We also need to mark copied objects.
5045 scan_root_cl = &scan_mark_root_cl;
5046 scan_klasses_cl = &scan_mark_klasses_cl_s;
5047 }
5048
5049 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5050
5051 // Don't scan the scavengable methods in the code cache as part
5052 // of strong root scanning. The code roots that point into a
5053 // region in the collection set are scanned when we scan the
5054 // region's RSet.
5055 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5056
5057 pss.start_strong_roots();
5058 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5059 SharedHeap::ScanningOption(so),
5060 scan_root_cl,
5061 &push_heap_rs_cl,
5062 scan_klasses_cl,
5063 worker_id);
5064 pss.end_strong_roots();
5065
5066 {
5067 double start = os::elapsedTime();
5068 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5069 evac.do_void();
5070 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5071 double term_ms = pss.term_time()*1000.0;
5072 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5073 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5074 }
5075 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5076 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5077
5078 if (ParallelGCVerbose) {
5079 MutexLocker x(stats_lock());
5080 pss.print_termination_stats(worker_id);
5081 }
5082
5083 assert(pss.refs()->is_empty(), "should be empty");
5084
5085 // Close the inner scope so that the ResourceMark and HandleMark
5086 // destructors are executed here and are included as part of the
5087 // "GC Worker Time".
5088 }
5089
5090 double end_time_ms = os::elapsedTime() * 1000.0;
5091 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5092 }
5093 };
5094
5095 // *** Common G1 Evacuation Stuff
5096
5097 // This method is run in a GC worker.
5098
5099 void
5100 G1CollectedHeap::
5101 g1_process_strong_roots(bool is_scavenging,
5102 ScanningOption so,
5103 OopClosure* scan_non_heap_roots,
5104 OopsInHeapRegionClosure* scan_rs,
5105 G1KlassScanClosure* scan_klasses,
5106 uint worker_i) {
5107
5108 // First scan the strong roots
5109 double ext_roots_start = os::elapsedTime();
5110 double closure_app_time_sec = 0.0;
5111
5112 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5113
5114 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5115 // Walk the code cache/strong code roots w/o buffering, because StarTask
5116 // cannot handle unaligned oop locations.
5117 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5118
5119 process_strong_roots(false, // no scoping; this is parallel code
5120 is_scavenging, so,
5121 &buf_scan_non_heap_roots,
5122 &eager_scan_code_roots,
5123 scan_klasses
5124 );
5125
5126 // Now the CM ref_processor roots.
5127 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5128 // We need to treat the discovered reference lists of the
5129 // concurrent mark ref processor as roots and keep entries
5130 // (which are added by the marking threads) on them live
5131 // until they can be processed at the end of marking.
5132 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5133 }
5134
5135 // Finish up any enqueued closure apps (attributed as object copy time).
5136 buf_scan_non_heap_roots.done();
5137
5138 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5139
5140 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5141
5142 double ext_root_time_ms =
5143 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5144
5145 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5146
5147 // During conc marking we have to filter the per-thread SATB buffers
5148 // to make sure we remove any oops into the CSet (which will show up
5149 // as implicitly live).
5150 double satb_filtering_ms = 0.0;
5151 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5152 if (mark_in_progress()) {
5153 double satb_filter_start = os::elapsedTime();
5154
5155 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5156
5157 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5158 }
5159 }
5160 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5161
5162 // If this is an initial mark pause, and we're not scanning
5163 // the entire code cache, we need to mark the oops in the
5164 // strong code root lists for the regions that are not in
5165 // the collection set.
5166 // Note all threads participate in this set of root tasks.
5167 double mark_strong_code_roots_ms = 0.0;
5168 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5169 double mark_strong_roots_start = os::elapsedTime();
5170 mark_strong_code_roots(worker_i);
5171 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5172 }
5173 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5174
5175 // Now scan the complement of the collection set.
5176 if (scan_rs != NULL) {
5177 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5178 }
5179 _process_strong_tasks->all_tasks_completed();
5180 }
5181
5182 void
5183 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5184 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5185 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5186 }
5187
5188 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5189 private:
5190 BoolObjectClosure* _is_alive;
5191 int _initial_string_table_size;
5192 int _initial_symbol_table_size;
5193
5194 bool _process_strings;
5195 int _strings_processed;
5196 int _strings_removed;
5197
5198 bool _process_symbols;
5199 int _symbols_processed;
5200 int _symbols_removed;
5201
5202 bool _do_in_parallel;
5203 public:
5204 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5205 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5206 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5207 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5208 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5209
5210 _initial_string_table_size = StringTable::the_table()->table_size();
5211 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5212 if (process_strings) {
5213 StringTable::clear_parallel_claimed_index();
5214 }
5215 if (process_symbols) {
5216 SymbolTable::clear_parallel_claimed_index();
5217 }
5218 }
5219
5220 ~G1StringSymbolTableUnlinkTask() {
5221 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5222 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5223 StringTable::parallel_claimed_index(), _initial_string_table_size));
5224 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5225 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5226 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5227 }
5228
5229 void work(uint worker_id) {
5230 if (_do_in_parallel) {
5231 int strings_processed = 0;
5232 int strings_removed = 0;
5233 int symbols_processed = 0;
5234 int symbols_removed = 0;
5235 if (_process_strings) {
5236 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5237 Atomic::add(strings_processed, &_strings_processed);
5238 Atomic::add(strings_removed, &_strings_removed);
5239 }
5240 if (_process_symbols) {
5241 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5242 Atomic::add(symbols_processed, &_symbols_processed);
5243 Atomic::add(symbols_removed, &_symbols_removed);
5244 }
5245 } else {
5246 if (_process_strings) {
5247 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5248 }
5249 if (_process_symbols) {
5250 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5251 }
5252 }
5253 }
5254
5255 size_t strings_processed() const { return (size_t)_strings_processed; }
5256 size_t strings_removed() const { return (size_t)_strings_removed; }
5257
5258 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5259 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5260 };
5261
5262 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5263 bool process_strings, bool process_symbols) {
5264 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5265 _g1h->workers()->active_workers() : 1);
5266
5267 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5268 if (G1CollectedHeap::use_parallel_gc_threads()) {
5269 set_par_threads(n_workers);
5270 workers()->run_task(&g1_unlink_task);
5271 set_par_threads(0);
5272 } else {
5273 g1_unlink_task.work(0);
5274 }
5275 if (G1TraceStringSymbolTableScrubbing) {
5276 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5277 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5278 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5279 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5280 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5281 }
5282
5283 if (G1StringDedup::is_enabled()) {
5284 G1StringDedup::unlink(is_alive);
5285 }
5286 }
5287
5288 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
5289 public:
5290 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
5291 *card_ptr = CardTableModRefBS::dirty_card_val();
5292 return true;
5293 }
5294 };
5295
5296 void G1CollectedHeap::redirty_logged_cards() {
5297 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5298 double redirty_logged_cards_start = os::elapsedTime();
5299
5300 RedirtyLoggedCardTableEntryFastClosure redirty;
5301 dirty_card_queue_set().set_closure(&redirty);
5302 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5303
5304 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5305 dcq.merge_bufferlists(&dirty_card_queue_set());
5306 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5307
5308 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5309 }
5310
5311 // Weak Reference Processing support
5312
5313 // An always "is_alive" closure that is used to preserve referents.
5314 // If the object is non-null then it's alive. Used in the preservation
5315 // of referent objects that are pointed to by reference objects
5316 // discovered by the CM ref processor.
5317 class G1AlwaysAliveClosure: public BoolObjectClosure {
5318 G1CollectedHeap* _g1;
5319 public:
5320 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5321 bool do_object_b(oop p) {
5322 if (p != NULL) {
5323 return true;
5324 }
5325 return false;
5326 }
5327 };
5328
5329 bool G1STWIsAliveClosure::do_object_b(oop p) {
5330 // An object is reachable if it is outside the collection set,
5331 // or is inside and copied.
5332 return !_g1->obj_in_cs(p) || p->is_forwarded();
5333 }
5334
5335 // Non Copying Keep Alive closure
5336 class G1KeepAliveClosure: public OopClosure {
5337 G1CollectedHeap* _g1;
5338 public:
5339 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5340 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5341 void do_oop( oop* p) {
5342 oop obj = *p;
5343
5344 if (_g1->obj_in_cs(obj)) {
5345 assert( obj->is_forwarded(), "invariant" );
5346 *p = obj->forwardee();
5347 }
5348 }
5349 };
5350
5351 // Copying Keep Alive closure - can be called from both
5352 // serial and parallel code as long as different worker
5353 // threads utilize different G1ParScanThreadState instances
5354 // and different queues.
5355
5356 class G1CopyingKeepAliveClosure: public OopClosure {
5357 G1CollectedHeap* _g1h;
5358 OopClosure* _copy_non_heap_obj_cl;
5359 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5360 G1ParScanThreadState* _par_scan_state;
5361
5362 public:
5363 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5364 OopClosure* non_heap_obj_cl,
5365 OopsInHeapRegionClosure* metadata_obj_cl,
5366 G1ParScanThreadState* pss):
5367 _g1h(g1h),
5368 _copy_non_heap_obj_cl(non_heap_obj_cl),
5369 _copy_metadata_obj_cl(metadata_obj_cl),
5370 _par_scan_state(pss)
5371 {}
5372
5373 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5374 virtual void do_oop( oop* p) { do_oop_work(p); }
5375
5376 template <class T> void do_oop_work(T* p) {
5377 oop obj = oopDesc::load_decode_heap_oop(p);
5378
5379 if (_g1h->obj_in_cs(obj)) {
5380 // If the referent object has been forwarded (either copied
5381 // to a new location or to itself in the event of an
5382 // evacuation failure) then we need to update the reference
5383 // field and, if both reference and referent are in the G1
5384 // heap, update the RSet for the referent.
5385 //
5386 // If the referent has not been forwarded then we have to keep
5387 // it alive by policy. Therefore we have copy the referent.
5388 //
5389 // If the reference field is in the G1 heap then we can push
5390 // on the PSS queue. When the queue is drained (after each
5391 // phase of reference processing) the object and it's followers
5392 // will be copied, the reference field set to point to the
5393 // new location, and the RSet updated. Otherwise we need to
5394 // use the the non-heap or metadata closures directly to copy
5395 // the referent object and update the pointer, while avoiding
5396 // updating the RSet.
5397
5398 if (_g1h->is_in_g1_reserved(p)) {
5399 _par_scan_state->push_on_queue(p);
5400 } else {
5401 assert(!Metaspace::contains((const void*)p),
5402 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5403 PTR_FORMAT, p));
5404 _copy_non_heap_obj_cl->do_oop(p);
5405 }
5406 }
5407 }
5408 };
5409
5410 // Serial drain queue closure. Called as the 'complete_gc'
5411 // closure for each discovered list in some of the
5412 // reference processing phases.
5413
5414 class G1STWDrainQueueClosure: public VoidClosure {
5415 protected:
5416 G1CollectedHeap* _g1h;
5417 G1ParScanThreadState* _par_scan_state;
5418
5419 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5420
5421 public:
5422 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5423 _g1h(g1h),
5424 _par_scan_state(pss)
5425 { }
5426
5427 void do_void() {
5428 G1ParScanThreadState* const pss = par_scan_state();
5429 pss->trim_queue();
5430 }
5431 };
5432
5433 // Parallel Reference Processing closures
5434
5435 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5436 // processing during G1 evacuation pauses.
5437
5438 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5439 private:
5440 G1CollectedHeap* _g1h;
5441 RefToScanQueueSet* _queues;
5442 FlexibleWorkGang* _workers;
5443 int _active_workers;
5444
5445 public:
5446 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5447 FlexibleWorkGang* workers,
5448 RefToScanQueueSet *task_queues,
5449 int n_workers) :
5450 _g1h(g1h),
5451 _queues(task_queues),
5452 _workers(workers),
5453 _active_workers(n_workers)
5454 {
5455 assert(n_workers > 0, "shouldn't call this otherwise");
5456 }
5457
5458 // Executes the given task using concurrent marking worker threads.
5459 virtual void execute(ProcessTask& task);
5460 virtual void execute(EnqueueTask& task);
5461 };
5462
5463 // Gang task for possibly parallel reference processing
5464
5465 class G1STWRefProcTaskProxy: public AbstractGangTask {
5466 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5467 ProcessTask& _proc_task;
5468 G1CollectedHeap* _g1h;
5469 RefToScanQueueSet *_task_queues;
5470 ParallelTaskTerminator* _terminator;
5471
5472 public:
5473 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5474 G1CollectedHeap* g1h,
5475 RefToScanQueueSet *task_queues,
5476 ParallelTaskTerminator* terminator) :
5477 AbstractGangTask("Process reference objects in parallel"),
5478 _proc_task(proc_task),
5479 _g1h(g1h),
5480 _task_queues(task_queues),
5481 _terminator(terminator)
5482 {}
5483
5484 virtual void work(uint worker_id) {
5485 // The reference processing task executed by a single worker.
5486 ResourceMark rm;
5487 HandleMark hm;
5488
5489 G1STWIsAliveClosure is_alive(_g1h);
5490
5491 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5492 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5493
5494 pss.set_evac_failure_closure(&evac_failure_cl);
5495
5496 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5497 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5498
5499 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5500 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5501
5502 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5503 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5504
5505 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5506 // We also need to mark copied objects.
5507 copy_non_heap_cl = ©_mark_non_heap_cl;
5508 copy_metadata_cl = ©_mark_metadata_cl;
5509 }
5510
5511 // Keep alive closure.
5512 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5513
5514 // Complete GC closure
5515 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5516
5517 // Call the reference processing task's work routine.
5518 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5519
5520 // Note we cannot assert that the refs array is empty here as not all
5521 // of the processing tasks (specifically phase2 - pp2_work) execute
5522 // the complete_gc closure (which ordinarily would drain the queue) so
5523 // the queue may not be empty.
5524 }
5525 };
5526
5527 // Driver routine for parallel reference processing.
5528 // Creates an instance of the ref processing gang
5529 // task and has the worker threads execute it.
5530 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5531 assert(_workers != NULL, "Need parallel worker threads.");
5532
5533 ParallelTaskTerminator terminator(_active_workers, _queues);
5534 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5535
5536 _g1h->set_par_threads(_active_workers);
5537 _workers->run_task(&proc_task_proxy);
5538 _g1h->set_par_threads(0);
5539 }
5540
5541 // Gang task for parallel reference enqueueing.
5542
5543 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5544 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5545 EnqueueTask& _enq_task;
5546
5547 public:
5548 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5549 AbstractGangTask("Enqueue reference objects in parallel"),
5550 _enq_task(enq_task)
5551 { }
5552
5553 virtual void work(uint worker_id) {
5554 _enq_task.work(worker_id);
5555 }
5556 };
5557
5558 // Driver routine for parallel reference enqueueing.
5559 // Creates an instance of the ref enqueueing gang
5560 // task and has the worker threads execute it.
5561
5562 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5563 assert(_workers != NULL, "Need parallel worker threads.");
5564
5565 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5566
5567 _g1h->set_par_threads(_active_workers);
5568 _workers->run_task(&enq_task_proxy);
5569 _g1h->set_par_threads(0);
5570 }
5571
5572 // End of weak reference support closures
5573
5574 // Abstract task used to preserve (i.e. copy) any referent objects
5575 // that are in the collection set and are pointed to by reference
5576 // objects discovered by the CM ref processor.
5577
5578 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5579 protected:
5580 G1CollectedHeap* _g1h;
5581 RefToScanQueueSet *_queues;
5582 ParallelTaskTerminator _terminator;
5583 uint _n_workers;
5584
5585 public:
5586 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5587 AbstractGangTask("ParPreserveCMReferents"),
5588 _g1h(g1h),
5589 _queues(task_queues),
5590 _terminator(workers, _queues),
5591 _n_workers(workers)
5592 { }
5593
5594 void work(uint worker_id) {
5595 ResourceMark rm;
5596 HandleMark hm;
5597
5598 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5599 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5600
5601 pss.set_evac_failure_closure(&evac_failure_cl);
5602
5603 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5604
5605
5606 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5607 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5608
5609 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5610 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5611
5612 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5613 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5614
5615 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5616 // We also need to mark copied objects.
5617 copy_non_heap_cl = ©_mark_non_heap_cl;
5618 copy_metadata_cl = ©_mark_metadata_cl;
5619 }
5620
5621 // Is alive closure
5622 G1AlwaysAliveClosure always_alive(_g1h);
5623
5624 // Copying keep alive closure. Applied to referent objects that need
5625 // to be copied.
5626 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5627
5628 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5629
5630 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5631 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5632
5633 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5634 // So this must be true - but assert just in case someone decides to
5635 // change the worker ids.
5636 assert(0 <= worker_id && worker_id < limit, "sanity");
5637 assert(!rp->discovery_is_atomic(), "check this code");
5638
5639 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5640 for (uint idx = worker_id; idx < limit; idx += stride) {
5641 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5642
5643 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5644 while (iter.has_next()) {
5645 // Since discovery is not atomic for the CM ref processor, we
5646 // can see some null referent objects.
5647 iter.load_ptrs(DEBUG_ONLY(true));
5648 oop ref = iter.obj();
5649
5650 // This will filter nulls.
5651 if (iter.is_referent_alive()) {
5652 iter.make_referent_alive();
5653 }
5654 iter.move_to_next();
5655 }
5656 }
5657
5658 // Drain the queue - which may cause stealing
5659 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5660 drain_queue.do_void();
5661 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5662 assert(pss.refs()->is_empty(), "should be");
5663 }
5664 };
5665
5666 // Weak Reference processing during an evacuation pause (part 1).
5667 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5668 double ref_proc_start = os::elapsedTime();
5669
5670 ReferenceProcessor* rp = _ref_processor_stw;
5671 assert(rp->discovery_enabled(), "should have been enabled");
5672
5673 // Any reference objects, in the collection set, that were 'discovered'
5674 // by the CM ref processor should have already been copied (either by
5675 // applying the external root copy closure to the discovered lists, or
5676 // by following an RSet entry).
5677 //
5678 // But some of the referents, that are in the collection set, that these
5679 // reference objects point to may not have been copied: the STW ref
5680 // processor would have seen that the reference object had already
5681 // been 'discovered' and would have skipped discovering the reference,
5682 // but would not have treated the reference object as a regular oop.
5683 // As a result the copy closure would not have been applied to the
5684 // referent object.
5685 //
5686 // We need to explicitly copy these referent objects - the references
5687 // will be processed at the end of remarking.
5688 //
5689 // We also need to do this copying before we process the reference
5690 // objects discovered by the STW ref processor in case one of these
5691 // referents points to another object which is also referenced by an
5692 // object discovered by the STW ref processor.
5693
5694 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5695 no_of_gc_workers == workers()->active_workers(),
5696 "Need to reset active GC workers");
5697
5698 set_par_threads(no_of_gc_workers);
5699 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5700 no_of_gc_workers,
5701 _task_queues);
5702
5703 if (G1CollectedHeap::use_parallel_gc_threads()) {
5704 workers()->run_task(&keep_cm_referents);
5705 } else {
5706 keep_cm_referents.work(0);
5707 }
5708
5709 set_par_threads(0);
5710
5711 // Closure to test whether a referent is alive.
5712 G1STWIsAliveClosure is_alive(this);
5713
5714 // Even when parallel reference processing is enabled, the processing
5715 // of JNI refs is serial and performed serially by the current thread
5716 // rather than by a worker. The following PSS will be used for processing
5717 // JNI refs.
5718
5719 // Use only a single queue for this PSS.
5720 G1ParScanThreadState pss(this, 0, NULL);
5721
5722 // We do not embed a reference processor in the copying/scanning
5723 // closures while we're actually processing the discovered
5724 // reference objects.
5725 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5726
5727 pss.set_evac_failure_closure(&evac_failure_cl);
5728
5729 assert(pss.refs()->is_empty(), "pre-condition");
5730
5731 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5732 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5733
5734 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5735 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5736
5737 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5738 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5739
5740 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5741 // We also need to mark copied objects.
5742 copy_non_heap_cl = ©_mark_non_heap_cl;
5743 copy_metadata_cl = ©_mark_metadata_cl;
5744 }
5745
5746 // Keep alive closure.
5747 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5748
5749 // Serial Complete GC closure
5750 G1STWDrainQueueClosure drain_queue(this, &pss);
5751
5752 // Setup the soft refs policy...
5753 rp->setup_policy(false);
5754
5755 ReferenceProcessorStats stats;
5756 if (!rp->processing_is_mt()) {
5757 // Serial reference processing...
5758 stats = rp->process_discovered_references(&is_alive,
5759 &keep_alive,
5760 &drain_queue,
5761 NULL,
5762 _gc_timer_stw,
5763 _gc_tracer_stw->gc_id());
5764 } else {
5765 // Parallel reference processing
5766 assert(rp->num_q() == no_of_gc_workers, "sanity");
5767 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5768
5769 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5770 stats = rp->process_discovered_references(&is_alive,
5771 &keep_alive,
5772 &drain_queue,
5773 &par_task_executor,
5774 _gc_timer_stw,
5775 _gc_tracer_stw->gc_id());
5776 }
5777
5778 _gc_tracer_stw->report_gc_reference_stats(stats);
5779 // We have completed copying any necessary live referent objects
5780 // (that were not copied during the actual pause) so we can
5781 // retire any active alloc buffers
5782 pss.retire_alloc_buffers();
5783 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5784
5785 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5786 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5787 }
5788
5789 // Weak Reference processing during an evacuation pause (part 2).
5790 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5791 double ref_enq_start = os::elapsedTime();
5792
5793 ReferenceProcessor* rp = _ref_processor_stw;
5794 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5795
5796 // Now enqueue any remaining on the discovered lists on to
5797 // the pending list.
5798 if (!rp->processing_is_mt()) {
5799 // Serial reference processing...
5800 rp->enqueue_discovered_references();
5801 } else {
5802 // Parallel reference enqueueing
5803
5804 assert(no_of_gc_workers == workers()->active_workers(),
5805 "Need to reset active workers");
5806 assert(rp->num_q() == no_of_gc_workers, "sanity");
5807 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5808
5809 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5810 rp->enqueue_discovered_references(&par_task_executor);
5811 }
5812
5813 rp->verify_no_references_recorded();
5814 assert(!rp->discovery_enabled(), "should have been disabled");
5815
5816 // FIXME
5817 // CM's reference processing also cleans up the string and symbol tables.
5818 // Should we do that here also? We could, but it is a serial operation
5819 // and could significantly increase the pause time.
5820
5821 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5822 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5823 }
5824
5825 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5826 _expand_heap_after_alloc_failure = true;
5827 _evacuation_failed = false;
5828
5829 // Should G1EvacuationFailureALot be in effect for this GC?
5830 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5831
5832 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5833
5834 // Disable the hot card cache.
5835 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5836 hot_card_cache->reset_hot_cache_claimed_index();
5837 hot_card_cache->set_use_cache(false);
5838
5839 uint n_workers;
5840 if (G1CollectedHeap::use_parallel_gc_threads()) {
5841 n_workers =
5842 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5843 workers()->active_workers(),
5844 Threads::number_of_non_daemon_threads());
5845 assert(UseDynamicNumberOfGCThreads ||
5846 n_workers == workers()->total_workers(),
5847 "If not dynamic should be using all the workers");
5848 workers()->set_active_workers(n_workers);
5849 set_par_threads(n_workers);
5850 } else {
5851 assert(n_par_threads() == 0,
5852 "Should be the original non-parallel value");
5853 n_workers = 1;
5854 }
5855
5856 G1ParTask g1_par_task(this, _task_queues);
5857
5858 init_for_evac_failure(NULL);
5859
5860 rem_set()->prepare_for_younger_refs_iterate(true);
5861
5862 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5863 double start_par_time_sec = os::elapsedTime();
5864 double end_par_time_sec;
5865
5866 {
5867 StrongRootsScope srs(this);
5868
5869 if (G1CollectedHeap::use_parallel_gc_threads()) {
5870 // The individual threads will set their evac-failure closures.
5871 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5872 // These tasks use ShareHeap::_process_strong_tasks
5873 assert(UseDynamicNumberOfGCThreads ||
5874 workers()->active_workers() == workers()->total_workers(),
5875 "If not dynamic should be using all the workers");
5876 workers()->run_task(&g1_par_task);
5877 } else {
5878 g1_par_task.set_for_termination(n_workers);
5879 g1_par_task.work(0);
5880 }
5881 end_par_time_sec = os::elapsedTime();
5882
5883 // Closing the inner scope will execute the destructor
5884 // for the StrongRootsScope object. We record the current
5885 // elapsed time before closing the scope so that time
5886 // taken for the SRS destructor is NOT included in the
5887 // reported parallel time.
5888 }
5889
5890 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5891 g1_policy()->phase_times()->record_par_time(par_time_ms);
5892
5893 double code_root_fixup_time_ms =
5894 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5895 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5896
5897 set_par_threads(0);
5898
5899 // Process any discovered reference objects - we have
5900 // to do this _before_ we retire the GC alloc regions
5901 // as we may have to copy some 'reachable' referent
5902 // objects (and their reachable sub-graphs) that were
5903 // not copied during the pause.
5904 process_discovered_references(n_workers);
5905
5906 // Weak root processing.
5907 {
5908 G1STWIsAliveClosure is_alive(this);
5909 G1KeepAliveClosure keep_alive(this);
5910 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5911 if (G1StringDedup::is_enabled()) {
5912 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5913 }
5914 }
5915
5916 release_gc_alloc_regions(n_workers, evacuation_info);
5917 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5918
5919 // Reset and re-enable the hot card cache.
5920 // Note the counts for the cards in the regions in the
5921 // collection set are reset when the collection set is freed.
5922 hot_card_cache->reset_hot_cache();
5923 hot_card_cache->set_use_cache(true);
5924
5925 // Migrate the strong code roots attached to each region in
5926 // the collection set. Ideally we would like to do this
5927 // after we have finished the scanning/evacuation of the
5928 // strong code roots for a particular heap region.
5929 migrate_strong_code_roots();
5930
5931 purge_code_root_memory();
5932
5933 if (g1_policy()->during_initial_mark_pause()) {
5934 // Reset the claim values set during marking the strong code roots
5935 reset_heap_region_claim_values();
5936 }
5937
5938 finalize_for_evac_failure();
5939
5940 if (evacuation_failed()) {
5941 remove_self_forwarding_pointers();
5942
5943 // Reset the G1EvacuationFailureALot counters and flags
5944 // Note: the values are reset only when an actual
5945 // evacuation failure occurs.
5946 NOT_PRODUCT(reset_evacuation_should_fail();)
5947 }
5948
5949 // Enqueue any remaining references remaining on the STW
5950 // reference processor's discovered lists. We need to do
5951 // this after the card table is cleaned (and verified) as
5952 // the act of enqueueing entries on to the pending list
5953 // will log these updates (and dirty their associated
5954 // cards). We need these updates logged to update any
5955 // RSets.
5956 enqueue_discovered_references(n_workers);
5957
5958 if (G1DeferredRSUpdate) {
5959 redirty_logged_cards();
5960 }
5961 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5962 }
5963
5964 void G1CollectedHeap::free_region(HeapRegion* hr,
5965 FreeRegionList* free_list,
5966 bool par,
5967 bool locked) {
5968 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5969 assert(!hr->is_empty(), "the region should not be empty");
5970 assert(free_list != NULL, "pre-condition");
5971
5972 // Clear the card counts for this region.
5973 // Note: we only need to do this if the region is not young
5974 // (since we don't refine cards in young regions).
5975 if (!hr->is_young()) {
5976 _cg1r->hot_card_cache()->reset_card_counts(hr);
5977 }
5978 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5979 free_list->add_ordered(hr);
5980 }
5981
5982 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5983 FreeRegionList* free_list,
5984 bool par) {
5985 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5986 assert(free_list != NULL, "pre-condition");
5987
5988 size_t hr_capacity = hr->capacity();
5989 // We need to read this before we make the region non-humongous,
5990 // otherwise the information will be gone.
5991 uint last_index = hr->last_hc_index();
5992 hr->set_notHumongous();
5993 free_region(hr, free_list, par);
5994
5995 uint i = hr->hrs_index() + 1;
5996 while (i < last_index) {
5997 HeapRegion* curr_hr = region_at(i);
5998 assert(curr_hr->continuesHumongous(), "invariant");
5999 curr_hr->set_notHumongous();
6000 free_region(curr_hr, free_list, par);
6001 i += 1;
6002 }
6003 }
6004
6005 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6006 const HeapRegionSetCount& humongous_regions_removed) {
6007 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6008 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6009 _old_set.bulk_remove(old_regions_removed);
6010 _humongous_set.bulk_remove(humongous_regions_removed);
6011 }
6012
6013 }
6014
6015 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6016 assert(list != NULL, "list can't be null");
6017 if (!list->is_empty()) {
6018 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6019 _free_list.add_ordered(list);
6020 }
6021 }
6022
6023 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6024 assert(_summary_bytes_used >= bytes,
6025 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6026 _summary_bytes_used, bytes));
6027 _summary_bytes_used -= bytes;
6028 }
6029
6030 class G1ParCleanupCTTask : public AbstractGangTask {
6031 G1SATBCardTableModRefBS* _ct_bs;
6032 G1CollectedHeap* _g1h;
6033 HeapRegion* volatile _su_head;
6034 public:
6035 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6036 G1CollectedHeap* g1h) :
6037 AbstractGangTask("G1 Par Cleanup CT Task"),
6038 _ct_bs(ct_bs), _g1h(g1h) { }
6039
6040 void work(uint worker_id) {
6041 HeapRegion* r;
6042 while (r = _g1h->pop_dirty_cards_region()) {
6043 clear_cards(r);
6044 }
6045 }
6046
6047 void clear_cards(HeapRegion* r) {
6048 // Cards of the survivors should have already been dirtied.
6049 if (!r->is_survivor()) {
6050 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6051 }
6052 }
6053 };
6054
6055 #ifndef PRODUCT
6056 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6057 G1CollectedHeap* _g1h;
6058 G1SATBCardTableModRefBS* _ct_bs;
6059 public:
6060 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6061 : _g1h(g1h), _ct_bs(ct_bs) { }
6062 virtual bool doHeapRegion(HeapRegion* r) {
6063 if (r->is_survivor()) {
6064 _g1h->verify_dirty_region(r);
6065 } else {
6066 _g1h->verify_not_dirty_region(r);
6067 }
6068 return false;
6069 }
6070 };
6071
6072 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6073 // All of the region should be clean.
6074 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6075 MemRegion mr(hr->bottom(), hr->end());
6076 ct_bs->verify_not_dirty_region(mr);
6077 }
6078
6079 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6080 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6081 // dirty allocated blocks as they allocate them. The thread that
6082 // retires each region and replaces it with a new one will do a
6083 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6084 // not dirty that area (one less thing to have to do while holding
6085 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6086 // is dirty.
6087 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6088 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6089 if (hr->is_young()) {
6090 ct_bs->verify_g1_young_region(mr);
6091 } else {
6092 ct_bs->verify_dirty_region(mr);
6093 }
6094 }
6095
6096 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6097 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6098 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6099 verify_dirty_region(hr);
6100 }
6101 }
6102
6103 void G1CollectedHeap::verify_dirty_young_regions() {
6104 verify_dirty_young_list(_young_list->first_region());
6105 }
6106 #endif
6107
6108 void G1CollectedHeap::cleanUpCardTable() {
6109 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6110 double start = os::elapsedTime();
6111
6112 {
6113 // Iterate over the dirty cards region list.
6114 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6115
6116 if (G1CollectedHeap::use_parallel_gc_threads()) {
6117 set_par_threads();
6118 workers()->run_task(&cleanup_task);
6119 set_par_threads(0);
6120 } else {
6121 while (_dirty_cards_region_list) {
6122 HeapRegion* r = _dirty_cards_region_list;
6123 cleanup_task.clear_cards(r);
6124 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6125 if (_dirty_cards_region_list == r) {
6126 // The last region.
6127 _dirty_cards_region_list = NULL;
6128 }
6129 r->set_next_dirty_cards_region(NULL);
6130 }
6131 }
6132 #ifndef PRODUCT
6133 if (G1VerifyCTCleanup || VerifyAfterGC) {
6134 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6135 heap_region_iterate(&cleanup_verifier);
6136 }
6137 #endif
6138 }
6139
6140 double elapsed = os::elapsedTime() - start;
6141 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6142 }
6143
6144 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6145 size_t pre_used = 0;
6146 FreeRegionList local_free_list("Local List for CSet Freeing");
6147
6148 double young_time_ms = 0.0;
6149 double non_young_time_ms = 0.0;
6150
6151 // Since the collection set is a superset of the the young list,
6152 // all we need to do to clear the young list is clear its
6153 // head and length, and unlink any young regions in the code below
6154 _young_list->clear();
6155
6156 G1CollectorPolicy* policy = g1_policy();
6157
6158 double start_sec = os::elapsedTime();
6159 bool non_young = true;
6160
6161 HeapRegion* cur = cs_head;
6162 int age_bound = -1;
6163 size_t rs_lengths = 0;
6164
6165 while (cur != NULL) {
6166 assert(!is_on_master_free_list(cur), "sanity");
6167 if (non_young) {
6168 if (cur->is_young()) {
6169 double end_sec = os::elapsedTime();
6170 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6171 non_young_time_ms += elapsed_ms;
6172
6173 start_sec = os::elapsedTime();
6174 non_young = false;
6175 }
6176 } else {
6177 if (!cur->is_young()) {
6178 double end_sec = os::elapsedTime();
6179 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6180 young_time_ms += elapsed_ms;
6181
6182 start_sec = os::elapsedTime();
6183 non_young = true;
6184 }
6185 }
6186
6187 rs_lengths += cur->rem_set()->occupied_locked();
6188
6189 HeapRegion* next = cur->next_in_collection_set();
6190 assert(cur->in_collection_set(), "bad CS");
6191 cur->set_next_in_collection_set(NULL);
6192 cur->set_in_collection_set(false);
6193
6194 if (cur->is_young()) {
6195 int index = cur->young_index_in_cset();
6196 assert(index != -1, "invariant");
6197 assert((uint) index < policy->young_cset_region_length(), "invariant");
6198 size_t words_survived = _surviving_young_words[index];
6199 cur->record_surv_words_in_group(words_survived);
6200
6201 // At this point the we have 'popped' cur from the collection set
6202 // (linked via next_in_collection_set()) but it is still in the
6203 // young list (linked via next_young_region()). Clear the
6204 // _next_young_region field.
6205 cur->set_next_young_region(NULL);
6206 } else {
6207 int index = cur->young_index_in_cset();
6208 assert(index == -1, "invariant");
6209 }
6210
6211 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6212 (!cur->is_young() && cur->young_index_in_cset() == -1),
6213 "invariant" );
6214
6215 if (!cur->evacuation_failed()) {
6216 MemRegion used_mr = cur->used_region();
6217
6218 // And the region is empty.
6219 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6220 pre_used += cur->used();
6221 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6222 } else {
6223 cur->uninstall_surv_rate_group();
6224 if (cur->is_young()) {
6225 cur->set_young_index_in_cset(-1);
6226 }
6227 cur->set_not_young();
6228 cur->set_evacuation_failed(false);
6229 // The region is now considered to be old.
6230 _old_set.add(cur);
6231 evacuation_info.increment_collectionset_used_after(cur->used());
6232 }
6233 cur = next;
6234 }
6235
6236 evacuation_info.set_regions_freed(local_free_list.length());
6237 policy->record_max_rs_lengths(rs_lengths);
6238 policy->cset_regions_freed();
6239
6240 double end_sec = os::elapsedTime();
6241 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6242
6243 if (non_young) {
6244 non_young_time_ms += elapsed_ms;
6245 } else {
6246 young_time_ms += elapsed_ms;
6247 }
6248
6249 prepend_to_freelist(&local_free_list);
6250 decrement_summary_bytes(pre_used);
6251 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6252 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6253 }
6254
6255 // This routine is similar to the above but does not record
6256 // any policy statistics or update free lists; we are abandoning
6257 // the current incremental collection set in preparation of a
6258 // full collection. After the full GC we will start to build up
6259 // the incremental collection set again.
6260 // This is only called when we're doing a full collection
6261 // and is immediately followed by the tearing down of the young list.
6262
6263 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6264 HeapRegion* cur = cs_head;
6265
6266 while (cur != NULL) {
6267 HeapRegion* next = cur->next_in_collection_set();
6268 assert(cur->in_collection_set(), "bad CS");
6269 cur->set_next_in_collection_set(NULL);
6270 cur->set_in_collection_set(false);
6271 cur->set_young_index_in_cset(-1);
6272 cur = next;
6273 }
6274 }
6275
6276 void G1CollectedHeap::set_free_regions_coming() {
6277 if (G1ConcRegionFreeingVerbose) {
6278 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6279 "setting free regions coming");
6280 }
6281
6282 assert(!free_regions_coming(), "pre-condition");
6283 _free_regions_coming = true;
6284 }
6285
6286 void G1CollectedHeap::reset_free_regions_coming() {
6287 assert(free_regions_coming(), "pre-condition");
6288
6289 {
6290 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6291 _free_regions_coming = false;
6292 SecondaryFreeList_lock->notify_all();
6293 }
6294
6295 if (G1ConcRegionFreeingVerbose) {
6296 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6297 "reset free regions coming");
6298 }
6299 }
6300
6301 void G1CollectedHeap::wait_while_free_regions_coming() {
6302 // Most of the time we won't have to wait, so let's do a quick test
6303 // first before we take the lock.
6304 if (!free_regions_coming()) {
6305 return;
6306 }
6307
6308 if (G1ConcRegionFreeingVerbose) {
6309 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6310 "waiting for free regions");
6311 }
6312
6313 {
6314 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6315 while (free_regions_coming()) {
6316 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6317 }
6318 }
6319
6320 if (G1ConcRegionFreeingVerbose) {
6321 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6322 "done waiting for free regions");
6323 }
6324 }
6325
6326 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6327 assert(heap_lock_held_for_gc(),
6328 "the heap lock should already be held by or for this thread");
6329 _young_list->push_region(hr);
6330 }
6331
6332 class NoYoungRegionsClosure: public HeapRegionClosure {
6333 private:
6334 bool _success;
6335 public:
6336 NoYoungRegionsClosure() : _success(true) { }
6337 bool doHeapRegion(HeapRegion* r) {
6338 if (r->is_young()) {
6339 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6340 r->bottom(), r->end());
6341 _success = false;
6342 }
6343 return false;
6344 }
6345 bool success() { return _success; }
6346 };
6347
6348 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6349 bool ret = _young_list->check_list_empty(check_sample);
6350
6351 if (check_heap) {
6352 NoYoungRegionsClosure closure;
6353 heap_region_iterate(&closure);
6354 ret = ret && closure.success();
6355 }
6356
6357 return ret;
6358 }
6359
6360 class TearDownRegionSetsClosure : public HeapRegionClosure {
6361 private:
6362 HeapRegionSet *_old_set;
6363
6364 public:
6365 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6366
6367 bool doHeapRegion(HeapRegion* r) {
6368 if (r->is_empty()) {
6369 // We ignore empty regions, we'll empty the free list afterwards
6370 } else if (r->is_young()) {
6371 // We ignore young regions, we'll empty the young list afterwards
6372 } else if (r->isHumongous()) {
6373 // We ignore humongous regions, we're not tearing down the
6374 // humongous region set
6375 } else {
6376 // The rest should be old
6377 _old_set->remove(r);
6378 }
6379 return false;
6380 }
6381
6382 ~TearDownRegionSetsClosure() {
6383 assert(_old_set->is_empty(), "post-condition");
6384 }
6385 };
6386
6387 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6388 assert_at_safepoint(true /* should_be_vm_thread */);
6389
6390 if (!free_list_only) {
6391 TearDownRegionSetsClosure cl(&_old_set);
6392 heap_region_iterate(&cl);
6393
6394 // Note that emptying the _young_list is postponed and instead done as
6395 // the first step when rebuilding the regions sets again. The reason for
6396 // this is that during a full GC string deduplication needs to know if
6397 // a collected region was young or old when the full GC was initiated.
6398 }
6399 _free_list.remove_all();
6400 }
6401
6402 class RebuildRegionSetsClosure : public HeapRegionClosure {
6403 private:
6404 bool _free_list_only;
6405 HeapRegionSet* _old_set;
6406 FreeRegionList* _free_list;
6407 size_t _total_used;
6408
6409 public:
6410 RebuildRegionSetsClosure(bool free_list_only,
6411 HeapRegionSet* old_set, FreeRegionList* free_list) :
6412 _free_list_only(free_list_only),
6413 _old_set(old_set), _free_list(free_list), _total_used(0) {
6414 assert(_free_list->is_empty(), "pre-condition");
6415 if (!free_list_only) {
6416 assert(_old_set->is_empty(), "pre-condition");
6417 }
6418 }
6419
6420 bool doHeapRegion(HeapRegion* r) {
6421 if (r->continuesHumongous()) {
6422 return false;
6423 }
6424
6425 if (r->is_empty()) {
6426 // Add free regions to the free list
6427 _free_list->add_as_tail(r);
6428 } else if (!_free_list_only) {
6429 assert(!r->is_young(), "we should not come across young regions");
6430
6431 if (r->isHumongous()) {
6432 // We ignore humongous regions, we left the humongous set unchanged
6433 } else {
6434 // The rest should be old, add them to the old set
6435 _old_set->add(r);
6436 }
6437 _total_used += r->used();
6438 }
6439
6440 return false;
6441 }
6442
6443 size_t total_used() {
6444 return _total_used;
6445 }
6446 };
6447
6448 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6449 assert_at_safepoint(true /* should_be_vm_thread */);
6450
6451 if (!free_list_only) {
6452 _young_list->empty_list();
6453 }
6454
6455 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6456 heap_region_iterate(&cl);
6457
6458 if (!free_list_only) {
6459 _summary_bytes_used = cl.total_used();
6460 }
6461 assert(_summary_bytes_used == recalculate_used(),
6462 err_msg("inconsistent _summary_bytes_used, "
6463 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6464 _summary_bytes_used, recalculate_used()));
6465 }
6466
6467 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6468 _refine_cte_cl->set_concurrent(concurrent);
6469 }
6470
6471 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6472 HeapRegion* hr = heap_region_containing(p);
6473 if (hr == NULL) {
6474 return false;
6475 } else {
6476 return hr->is_in(p);
6477 }
6478 }
6479
6480 // Methods for the mutator alloc region
6481
6482 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6483 bool force) {
6484 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6485 assert(!force || g1_policy()->can_expand_young_list(),
6486 "if force is true we should be able to expand the young list");
6487 bool young_list_full = g1_policy()->is_young_list_full();
6488 if (force || !young_list_full) {
6489 HeapRegion* new_alloc_region = new_region(word_size,
6490 false /* is_old */,
6491 false /* do_expand */);
6492 if (new_alloc_region != NULL) {
6493 set_region_short_lived_locked(new_alloc_region);
6494 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6495 return new_alloc_region;
6496 }
6497 }
6498 return NULL;
6499 }
6500
6501 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6502 size_t allocated_bytes) {
6503 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6504 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6505
6506 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6507 _summary_bytes_used += allocated_bytes;
6508 _hr_printer.retire(alloc_region);
6509 // We update the eden sizes here, when the region is retired,
6510 // instead of when it's allocated, since this is the point that its
6511 // used space has been recored in _summary_bytes_used.
6512 g1mm()->update_eden_size();
6513 }
6514
6515 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6516 bool force) {
6517 return _g1h->new_mutator_alloc_region(word_size, force);
6518 }
6519
6520 void G1CollectedHeap::set_par_threads() {
6521 // Don't change the number of workers. Use the value previously set
6522 // in the workgroup.
6523 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6524 uint n_workers = workers()->active_workers();
6525 assert(UseDynamicNumberOfGCThreads ||
6526 n_workers == workers()->total_workers(),
6527 "Otherwise should be using the total number of workers");
6528 if (n_workers == 0) {
6529 assert(false, "Should have been set in prior evacuation pause.");
6530 n_workers = ParallelGCThreads;
6531 workers()->set_active_workers(n_workers);
6532 }
6533 set_par_threads(n_workers);
6534 }
6535
6536 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6537 size_t allocated_bytes) {
6538 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6539 }
6540
6541 // Methods for the GC alloc regions
6542
6543 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6544 uint count,
6545 GCAllocPurpose ap) {
6546 assert(FreeList_lock->owned_by_self(), "pre-condition");
6547
6548 if (count < g1_policy()->max_regions(ap)) {
6549 bool survivor = (ap == GCAllocForSurvived);
6550 HeapRegion* new_alloc_region = new_region(word_size,
6551 !survivor,
6552 true /* do_expand */);
6553 if (new_alloc_region != NULL) {
6554 // We really only need to do this for old regions given that we
6555 // should never scan survivors. But it doesn't hurt to do it
6556 // for survivors too.
6557 new_alloc_region->set_saved_mark();
6558 if (survivor) {
6559 new_alloc_region->set_survivor();
6560 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6561 } else {
6562 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6563 }
6564 bool during_im = g1_policy()->during_initial_mark_pause();
6565 new_alloc_region->note_start_of_copying(during_im);
6566 return new_alloc_region;
6567 } else {
6568 g1_policy()->note_alloc_region_limit_reached(ap);
6569 }
6570 }
6571 return NULL;
6572 }
6573
6574 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6575 size_t allocated_bytes,
6576 GCAllocPurpose ap) {
6577 bool during_im = g1_policy()->during_initial_mark_pause();
6578 alloc_region->note_end_of_copying(during_im);
6579 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6580 if (ap == GCAllocForSurvived) {
6581 young_list()->add_survivor_region(alloc_region);
6582 } else {
6583 _old_set.add(alloc_region);
6584 }
6585 _hr_printer.retire(alloc_region);
6586 }
6587
6588 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6589 bool force) {
6590 assert(!force, "not supported for GC alloc regions");
6591 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6592 }
6593
6594 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6595 size_t allocated_bytes) {
6596 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6597 GCAllocForSurvived);
6598 }
6599
6600 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6601 bool force) {
6602 assert(!force, "not supported for GC alloc regions");
6603 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6604 }
6605
6606 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6607 size_t allocated_bytes) {
6608 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6609 GCAllocForTenured);
6610 }
6611 // Heap region set verification
6612
6613 class VerifyRegionListsClosure : public HeapRegionClosure {
6614 private:
6615 HeapRegionSet* _old_set;
6616 HeapRegionSet* _humongous_set;
6617 FreeRegionList* _free_list;
6618
6619 public:
6620 HeapRegionSetCount _old_count;
6621 HeapRegionSetCount _humongous_count;
6622 HeapRegionSetCount _free_count;
6623
6624 VerifyRegionListsClosure(HeapRegionSet* old_set,
6625 HeapRegionSet* humongous_set,
6626 FreeRegionList* free_list) :
6627 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6628 _old_count(), _humongous_count(), _free_count(){ }
6629
6630 bool doHeapRegion(HeapRegion* hr) {
6631 if (hr->continuesHumongous()) {
6632 return false;
6633 }
6634
6635 if (hr->is_young()) {
6636 // TODO
6637 } else if (hr->startsHumongous()) {
6638 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num()));
6639 _humongous_count.increment(1u, hr->capacity());
6640 } else if (hr->is_empty()) {
6641 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num()));
6642 _free_count.increment(1u, hr->capacity());
6643 } else {
6644 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num()));
6645 _old_count.increment(1u, hr->capacity());
6646 }
6647 return false;
6648 }
6649
6650 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6651 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6652 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6653 old_set->total_capacity_bytes(), _old_count.capacity()));
6654
6655 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6656 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6657 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6658
6659 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6660 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6661 free_list->total_capacity_bytes(), _free_count.capacity()));
6662 }
6663 };
6664
6665 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6666 HeapWord* bottom) {
6667 HeapWord* end = bottom + HeapRegion::GrainWords;
6668 MemRegion mr(bottom, end);
6669 assert(_g1_reserved.contains(mr), "invariant");
6670 // This might return NULL if the allocation fails
6671 return new HeapRegion(hrs_index, _bot_shared, mr);
6672 }
6673
6674 void G1CollectedHeap::verify_region_sets() {
6675 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6676
6677 // First, check the explicit lists.
6678 _free_list.verify_list();
6679 {
6680 // Given that a concurrent operation might be adding regions to
6681 // the secondary free list we have to take the lock before
6682 // verifying it.
6683 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6684 _secondary_free_list.verify_list();
6685 }
6686
6687 // If a concurrent region freeing operation is in progress it will
6688 // be difficult to correctly attributed any free regions we come
6689 // across to the correct free list given that they might belong to
6690 // one of several (free_list, secondary_free_list, any local lists,
6691 // etc.). So, if that's the case we will skip the rest of the
6692 // verification operation. Alternatively, waiting for the concurrent
6693 // operation to complete will have a non-trivial effect on the GC's
6694 // operation (no concurrent operation will last longer than the
6695 // interval between two calls to verification) and it might hide
6696 // any issues that we would like to catch during testing.
6697 if (free_regions_coming()) {
6698 return;
6699 }
6700
6701 // Make sure we append the secondary_free_list on the free_list so
6702 // that all free regions we will come across can be safely
6703 // attributed to the free_list.
6704 append_secondary_free_list_if_not_empty_with_lock();
6705
6706 // Finally, make sure that the region accounting in the lists is
6707 // consistent with what we see in the heap.
6708
6709 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6710 heap_region_iterate(&cl);
6711 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6712 }
6713
6714 // Optimized nmethod scanning
6715
6716 class RegisterNMethodOopClosure: public OopClosure {
6717 G1CollectedHeap* _g1h;
6718 nmethod* _nm;
6719
6720 template <class T> void do_oop_work(T* p) {
6721 T heap_oop = oopDesc::load_heap_oop(p);
6722 if (!oopDesc::is_null(heap_oop)) {
6723 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6724 HeapRegion* hr = _g1h->heap_region_containing(obj);
6725 assert(!hr->continuesHumongous(),
6726 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6727 " starting at "HR_FORMAT,
6728 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6729
6730 // HeapRegion::add_strong_code_root() avoids adding duplicate
6731 // entries but having duplicates is OK since we "mark" nmethods
6732 // as visited when we scan the strong code root lists during the GC.
6733 hr->add_strong_code_root(_nm);
6734 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6735 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6736 _nm, HR_FORMAT_PARAMS(hr)));
6737 }
6738 }
6739
6740 public:
6741 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6742 _g1h(g1h), _nm(nm) {}
6743
6744 void do_oop(oop* p) { do_oop_work(p); }
6745 void do_oop(narrowOop* p) { do_oop_work(p); }
6746 };
6747
6748 class UnregisterNMethodOopClosure: public OopClosure {
6749 G1CollectedHeap* _g1h;
6750 nmethod* _nm;
6751
6752 template <class T> void do_oop_work(T* p) {
6753 T heap_oop = oopDesc::load_heap_oop(p);
6754 if (!oopDesc::is_null(heap_oop)) {
6755 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6756 HeapRegion* hr = _g1h->heap_region_containing(obj);
6757 assert(!hr->continuesHumongous(),
6758 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6759 " starting at "HR_FORMAT,
6760 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6761
6762 hr->remove_strong_code_root(_nm);
6763 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6764 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6765 _nm, HR_FORMAT_PARAMS(hr)));
6766 }
6767 }
6768
6769 public:
6770 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6771 _g1h(g1h), _nm(nm) {}
6772
6773 void do_oop(oop* p) { do_oop_work(p); }
6774 void do_oop(narrowOop* p) { do_oop_work(p); }
6775 };
6776
6777 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6778 CollectedHeap::register_nmethod(nm);
6779
6780 guarantee(nm != NULL, "sanity");
6781 RegisterNMethodOopClosure reg_cl(this, nm);
6782 nm->oops_do(®_cl);
6783 }
6784
6785 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6786 CollectedHeap::unregister_nmethod(nm);
6787
6788 guarantee(nm != NULL, "sanity");
6789 UnregisterNMethodOopClosure reg_cl(this, nm);
6790 nm->oops_do(®_cl, true);
6791 }
6792
6793 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6794 public:
6795 bool doHeapRegion(HeapRegion *hr) {
6796 assert(!hr->isHumongous(),
6797 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6798 HR_FORMAT_PARAMS(hr)));
6799 hr->migrate_strong_code_roots();
6800 return false;
6801 }
6802 };
6803
6804 void G1CollectedHeap::migrate_strong_code_roots() {
6805 MigrateCodeRootsHeapRegionClosure cl;
6806 double migrate_start = os::elapsedTime();
6807 collection_set_iterate(&cl);
6808 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6809 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6810 }
6811
6812 void G1CollectedHeap::purge_code_root_memory() {
6813 double purge_start = os::elapsedTime();
6814 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6815 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6816 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6817 }
6818
6819 // Mark all the code roots that point into regions *not* in the
6820 // collection set.
6821 //
6822 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6823 // walking the the code roots lists of regions not in the collection
6824 // set. Suppose we have an nmethod (M) that points to objects in two
6825 // separate regions - one in the collection set (R1) and one not (R2).
6826 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6827 // nmethod M when walking the code roots for R1. When we come to scan
6828 // the code roots for R2, we would see that M is already marked and it
6829 // would be skipped and the objects in R2 that are referenced from M
6830 // would not be evacuated.
6831
6832 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6833
6834 class MarkStrongCodeRootOopClosure: public OopClosure {
6835 ConcurrentMark* _cm;
6836 HeapRegion* _hr;
6837 uint _worker_id;
6838
6839 template <class T> void do_oop_work(T* p) {
6840 T heap_oop = oopDesc::load_heap_oop(p);
6841 if (!oopDesc::is_null(heap_oop)) {
6842 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6843 // Only mark objects in the region (which is assumed
6844 // to be not in the collection set).
6845 if (_hr->is_in(obj)) {
6846 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6847 }
6848 }
6849 }
6850
6851 public:
6852 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6853 _cm(cm), _hr(hr), _worker_id(worker_id) {
6854 assert(!_hr->in_collection_set(), "sanity");
6855 }
6856
6857 void do_oop(narrowOop* p) { do_oop_work(p); }
6858 void do_oop(oop* p) { do_oop_work(p); }
6859 };
6860
6861 MarkStrongCodeRootOopClosure _oop_cl;
6862
6863 public:
6864 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6865 _oop_cl(cm, hr, worker_id) {}
6866
6867 void do_code_blob(CodeBlob* cb) {
6868 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6869 if (nm != NULL) {
6870 nm->oops_do(&_oop_cl);
6871 }
6872 }
6873 };
6874
6875 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6876 G1CollectedHeap* _g1h;
6877 uint _worker_id;
6878
6879 public:
6880 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6881 _g1h(g1h), _worker_id(worker_id) {}
6882
6883 bool doHeapRegion(HeapRegion *hr) {
6884 HeapRegionRemSet* hrrs = hr->rem_set();
6885 if (hr->continuesHumongous()) {
6886 // Code roots should never be attached to a continuation of a humongous region
6887 assert(hrrs->strong_code_roots_list_length() == 0,
6888 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6889 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6890 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6891 hrrs->strong_code_roots_list_length()));
6892 return false;
6893 }
6894
6895 if (hr->in_collection_set()) {
6896 // Don't mark code roots into regions in the collection set here.
6897 // They will be marked when we scan them.
6898 return false;
6899 }
6900
6901 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6902 hr->strong_code_roots_do(&cb_cl);
6903 return false;
6904 }
6905 };
6906
6907 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6908 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6909 if (G1CollectedHeap::use_parallel_gc_threads()) {
6910 heap_region_par_iterate_chunked(&cl,
6911 worker_id,
6912 workers()->active_workers(),
6913 HeapRegion::ParMarkRootClaimValue);
6914 } else {
6915 heap_region_iterate(&cl);
6916 }
6917 }
6918
6919 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6920 G1CollectedHeap* _g1h;
6921
6922 public:
6923 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6924 _g1h(g1h) {}
6925
6926 void do_code_blob(CodeBlob* cb) {
6927 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6928 if (nm == NULL) {
6929 return;
6930 }
6931
6932 if (ScavengeRootsInCode) {
6933 _g1h->register_nmethod(nm);
6934 }
6935 }
6936 };
6937
6938 void G1CollectedHeap::rebuild_strong_code_roots() {
6939 RebuildStrongCodeRootClosure blob_cl(this);
6940 CodeCache::blobs_do(&blob_cl);
6941 }